Sample records for hardening conditions increased

  1. Determination of Constant Parameters of Copper as Power-Law Hardening Material at Different Test Conditions

    Kowser Md. A.


    Full Text Available In this paper a technique has been developed to determine constant parameters of copper as a power-law hardening material by tensile test approach. A work-hardening process is used to describe the increase of the stress level necessary to continue plastic deformation. A computer program is used to show the variation of the stress-strain relation for different values of stress hardening exponent, n and power-law hardening constant, α . Due to its close tolerances, excellent corrosion resistance and high material strength, in this analysis copper (Cu has been selected as the material. As a power-law hardening material, Cu has been used to compute stress hardening exponent, n and power-law hardening constant, α from tensile test experiment without heat treatment and after heat treatment. A wealth of information about mechanical behavior of a material can be determined by conducting a simple tensile test in which a cylindrical specimen of a uniform cross-section is pulled until it ruptures or fractures into separate pieces. The original cross sectional area and gauge length are measured prior to conducting the test and the applied load and gauge deformation are continuously measured throughout the test. Based on the initial geometry of the sample, the engineering stress-strain behavior (stress-strain curve can be easily generated from which numerous mechanical properties, such as the yield strength and elastic modulus, can be determined. A universal testing machine is utilized to apply the load in a continuously increasing (ramp manner according to ASTM specifications. Finally, theoretical results are compared with these obtained from experiments where the nature of curves is found similar to each other. It is observed that there is a significant change of the value of n obtained with and without heat treatment it means the value of n should be determined for the heat treated condition of copper material for their applications in engineering

  2. The hardening compositions from the burnt rocks for using in the mining conditions

    Galpern, E.I. [Inst. of Industrial Construction and Building, Donetsk, (Ukraine); Pashchenko, L.V.; Saranchuk, V.I. [Inst. of Physical, Organic and Coal Chemistry NAS, Donetsk (Ukraine)


    The complex investigation of burnt coal rocks as raw material for hardening alkaline cements reception have been carried out. The hardening composition on the base of pit heap burnt rocks for the grouting of worked-out space in mining conditions have been obtained. It has been shown that burnt rocks activation by blast granulated slag and water glass allowed to obtain the cements of needed strength. The influence of main technological factors on obtained hardening composition properties have been studied. (orig.)

  3. Development of Bake Hardening Effect by Plastic Deformation and Annealing Conditions

    Kvačkaj, T.


    Full Text Available The paper deals with the classification of steel sheets for automotives industry on the basis of strength and structural characteristics. Experimental works were aimed to obtain the best possible strengthening parameters as well as work hardening and solid solution ferrite hardening, which are the result of thermal activation of interstitial carbon atoms during paint-baking of auto body. Hardening process coming from interstitial atoms is realized as two-step process. The first step is BH (bake hardening effect achieved by interaction of interstitial atoms with dislocations. The Cottrels atmosphere is obtained. The second step of BH effect is to produced the hardening from precipitation of the carbon atoms in e-carbides, or formation of Fe32C4 carbides. WH (work hardening effect is obtained as dislocation hardening from plastic deformations during sheet deep drawing. Experimental works were aimed at as to achieve such plastic material properties after cold rolling, annealing and skin-pass rolling, which would be able to classify the material ZStE220BH into the drawing categories at the level of DQ – DDQ. As resulting from the experimental results, the optimal treatment conditions for the maximal sum (WH+BH = 86 MPa are as follows: total cold rolling deformation ecold = 65 %, annealing temperature Tanneal. = 700 °C.

  4. Laser Surface Hardened Patterns for Increased Ballistic Protection


    dictate the severity of quench. In other words, unique martensitic/ bainitic microstructures, which cannot be developed by the conventional heat...alloy composition and the metallurgical conditions produced by the laser (finer grain size and martensitic/ bainitic phase) could be expected to lower


    V. N. Fedulov


    Full Text Available The theoretical aspects of development of the complex-alloyed steel compounds for cutting parts of high-speed instrument, particularly influence of alloying elements on its structure and characteristics are considered. It is shown that combined alloying of steel by carbon, chrome, silicon, manganese, vanadium and molybdenum in a certain proportion allows to reach the intended aim, achieving at the same time increase of solidity, impact elasticity and heat stability.

  6. The influence of the hardening conditions on the mechanical properties of ductile cast iron

    T. Giętka


    Full Text Available Ductile cast iron has been austempered according to two variants. The first treatment variant was austenitizing at a temperature tγ = 830, 860 and 900 0C and holding at a temperature tpi = 400 and 300 0C for 8 ÷ 64 min. Second variant treatment was two-phase austenitizing. Firstly, it was heated at a temperature tγ = 950 0C and after forecooling and chilling at a temperature tγ’ = 900, 860 and 830 0C isothermal process was conducted in the same conditions as in the first variant. The cast iron with ferritic matrix was austempered. After hardening the mechanical (Rp0,2, Rm and plastic (A5 properties were examined as well as the microstructure of matrix and hardness. It was noticed that the heat treatment carried out according to variants I and II lead to attaining cast iron of grade: ADI EN-GJS-800-8, EN-GJS-1200-2, EN-GJS-1400-1 according to PN–EN 1564 : 2000; in addition, ductility of these grades was 1,5÷4 times bigger than the mini-mum standard material requirements.

  7. Influence of Microstructure and Process Conditions on Simultaneous Low-Temperature Surface Hardening and Bulk Precipitation Hardening of Nanoflex®

    Bottoli, Federico; Winther, Grethe; Christiansen, Thomas L.


    and times for these essentially different hardening mechanisms are compatible. The effect of the processing history of the steel on the nitrided/nitrocarburized case was investigated by varying the amounts of austenite and martensite through variation of the degree of plastic deformation by tensile strain...

  8. Meat Feeding Restricts Rapid Cold Hardening Response and Increases Thermal Activity Thresholds of Adult Blow Flies, Calliphora vicina (Diptera: Calliphoridae).

    Coleman, Paul C; Bale, Jeffrey S; Hayward, Scott A L


    Virtually all temperate insects survive the winter by entering a physiological state of reduced metabolic activity termed diapause. However, there is increasing evidence that climate change is disrupting the diapause response resulting in non-diapause life stages encountering periods of winter cold. This is a significant problem for adult life stages in particular, as they must remain mobile, periodically feed, and potentially initiate reproductive development at a time when resources should be diverted to enhance stress tolerance. Here we present the first evidence of protein/meat feeding restricting rapid cold hardening (RCH) ability and increasing low temperature activity thresholds. No RCH response was noted in adult female blow flies (Calliphora vicina Robineau-Desvoidy) fed a sugar, water and liver (SWL) diet, while a strong RCH response was seen in females fed a diet of sugar and water (SW) only. The RCH response in SW flies was induced at temperatures as high as 10°C, but was strongest following 3h at 0°C. The CTmin (loss of coordinated movement) and chill coma (final appendage twitch) temperature of SWL females (-0.3 ± 0.5°C and -4.9 ± 0.5°C, respectively) was significantly higher than for SW females (-3.2 ± 0.8°C and -8.5 ± 0.6°C). We confirmed this was not directly the result of altered extracellular K+, as activity thresholds of alanine-fed adults were not significantly different from SW flies. Instead we suggest the loss of cold tolerance is more likely the result of diverting resource allocation to egg development. Between 2009 and 2013 winter air temperatures in Birmingham, UK, fell below the CTmin of SW and SWL flies on 63 and 195 days, respectively, suggesting differential exposure to chill injury depending on whether adults had access to meat or not. We conclude that disruption of diapause could significantly impact on winter survival through loss of synchrony in the timing of active feeding and reproductive development with favourable

  9. Meat Feeding Restricts Rapid Cold Hardening Response and Increases Thermal Activity Thresholds of Adult Blow Flies, Calliphora vicina (Diptera: Calliphoridae.

    Paul C Coleman

    Full Text Available Virtually all temperate insects survive the winter by entering a physiological state of reduced metabolic activity termed diapause. However, there is increasing evidence that climate change is disrupting the diapause response resulting in non-diapause life stages encountering periods of winter cold. This is a significant problem for adult life stages in particular, as they must remain mobile, periodically feed, and potentially initiate reproductive development at a time when resources should be diverted to enhance stress tolerance. Here we present the first evidence of protein/meat feeding restricting rapid cold hardening (RCH ability and increasing low temperature activity thresholds. No RCH response was noted in adult female blow flies (Calliphora vicina Robineau-Desvoidy fed a sugar, water and liver (SWL diet, while a strong RCH response was seen in females fed a diet of sugar and water (SW only. The RCH response in SW flies was induced at temperatures as high as 10°C, but was strongest following 3h at 0°C. The CTmin (loss of coordinated movement and chill coma (final appendage twitch temperature of SWL females (-0.3 ± 0.5°C and -4.9 ± 0.5°C, respectively was significantly higher than for SW females (-3.2 ± 0.8°C and -8.5 ± 0.6°C. We confirmed this was not directly the result of altered extracellular K+, as activity thresholds of alanine-fed adults were not significantly different from SW flies. Instead we suggest the loss of cold tolerance is more likely the result of diverting resource allocation to egg development. Between 2009 and 2013 winter air temperatures in Birmingham, UK, fell below the CTmin of SW and SWL flies on 63 and 195 days, respectively, suggesting differential exposure to chill injury depending on whether adults had access to meat or not. We conclude that disruption of diapause could significantly impact on winter survival through loss of synchrony in the timing of active feeding and reproductive development with

  10. Rapid cold hardening process of insects and its ecologically adaptive significance

    WANG Xianhui; QI Xianlei; KANG Le


    In contrast to overwintering cold hardening, a rapid cold hardening process has recently been described in insects. This process can rapidly enhance cold tolerance of insects in several hours or even minutes. The characteristics of rapid cold hardening include inducing conditions, cold hardening effects, and fitness costs. Physiological and biochemical mechanisms of rapid cold hardening include rapid changes in the phospholipid composition and the increase in hemolymph osmolalities, polyols production, proline and cold-induced proteins. Moreover, there are different views about the ecologically adaptive significance of rapid cold hardening in insects. This paper reviews research results about rapid cold hardening of insects since 1987, focusing on forms of cold injury, strategies of cold tolerance, and definitions, characteristics, physiological and biochemical mechanisms and adaptive significance of rapid cold hardening.

  11. Nanostructured Hardening of Hard Alloys Surface Layers Through Electron Irradiation in Heavy Inert Gas Plasma Conditions

    Ovcharenko, V. E.; Ivanov, Yu F.; Ivanov, K. V.; Mokhovikov, A. A.; Baohai, Yu; Hua, Xu Yun


    The paper presents research and experimental findings which prove that metal ceramic composite surface layer contains micro constituents’ hierarchies in the form of secondary nano sized inclusions inside ceramic phases. These inclusions have typical dimensions from several tens to several hundreds of nano meters. It has been shown that multi level structure-phase condition, developed in a nano sized area, effects physical and tribological properties of a metal ceramic composite surface layer.

  12. Development of methods for predicting large crack growth in elastic-plastic work-hardening materials in fully plastic conditions

    Ford, Hugh; Turner, C. E.; Fenner, R. T.; Curr, R. M.; Ivankovic, A.


    The objects of the first, exploratory, stage of the project were listed as: (1) to make a detailed and critical review of the Boundary Element method as already published and with regard to elastic-plastic fracture mechanics, to assess its potential for handling present concepts in two-dimensional and three-dimensional cases. To this was subsequently added the Finite Volume method and certain aspects of the Finite Element method for comparative purposes; (2) to assess the further steps needed to apply the methods so far developed to the general field, covering a practical range of geometries, work hardening materials, and composites: to consider their application under higher temperature conditions; (3) to re-assess the present stage of development of the energy dissipation rate, crack tip opening angle and J-integral models in relation to the possibilities of producing a unified technology with the previous two items; and (4) to report on the feasibility and promise of this combined approach and, if appropriate, make recommendations for the second stage aimed at developing a generalized crack growth technology for its application to real-life problems.

  13. Study of High Fluence Radiation-induced Swelling and Hardening under Light Water Reactor Conditions

    Golubov, Stanislav I. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Barashev, Alexander V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Stoller, Roger E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)


    This report documents a comprehensive model that has been developed to enable simulations of microstructural evolution under the irradiation conditions typical of light water reactor (LWR) internal components. The model, which accounts cascade production of point defects and vacancy, interstitial faulted dislocation loops, interstitial clusters migrating one-dimensionally and the evolution of the network dislocation structure, has been parameterized to account damage accumulation in austenitic stainless steels. Nucleation and growth of an ensemble of cavities is based on accounting the residual and produced by irradiation He atoms and existence of the dislocation and production biases. Additional applications and potential future developments for the model are also discussed.

  14. Key role of work hardening in superconductivity/superfluidity, heat conductivity and ultimate strain increase, evolution, cancer, aging and other phase transitions

    Kisel, V P


    The shear/laminar flow of liquids/gas/plasma/biological cells (BC), etc. is equivalent to dislocation-like shear of solids. The turbulent flow is the next stage of deformation/ multiplication of dislocation-like defects and their ordering in sub-grains and grain-boundaries, then grains slip-rotation in the direction approximately perpendicular to the shear flow. It is shown that phase transitions are governed by unified deformation hardening/softening under hydrostatic pressure, particle irradiation and impurity (isotope) chemical pressure, hard confining conditions and cooling, etc. thus changing electric, magnetic, ferroelectric, thermal, optical properties.1-2 Dislocation-like work hardening, DWH, is determined by non-monotonous properties of dislocation double edge-cross-jog slip, and ultrastrong DWH gives the lowest drag for any dislocation-like plasticity at phase transitions. This provides the same micromechanisms of the ultimate stage of conventional deformation (superfluidity) of ordinary liquids, i....

  15. Effects of Vacuum-Carburizing Conditions on Surface-Hardened Layer Properties of Transformation-Induced Plasticity-Aided Martensitic Steel

    Koh-ichi Sugimoto


    Full Text Available The effects of carbon potential in vacuum-carburization on the surface-hardened layer properties of the 0.2%C-1.5%Si-1.5%Mn-1.0%Cr-0.05%Nb transformation-induced plasticity-aided martensitic steel were investigated for the fabrication of precision gears. The volume fraction of retained austenite and hardness in the surface hardened layer of the steel increased with increasing carbon potential. Subsequent fine-particle peening enhanced the hardness and the compressive residual stress via severe plastic deformation and strain-induced martensite transformation, especially under a high carbon potential. The severe plastic deformation mainly contributed to increased hardness and compressive residual stress and the contribution of the strain-induced martensitic transformation was relatively small.

  16. EXAFS investigation on U(VI) immobilization in hardened cement paste. Influence of experimental conditions on speciation

    Mace, N.; Wieland, E.; Daehn, R.; Tits, J. [Paul Scherrer Inst. (PSI), Villigen (Switzerland). Lab. for Waste Management; Scheinost, A.C. [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Inst. of Resource Ecology; Rossendorf Beamline (ROBL), Grenoble (France). ESRF


    Extended X-ray absorption fine structure (EXAFS) spectroscopy has been used to investigate the coordination environment of U(VI) in cementitious materials. The EXAFS measurements were carried out on U(VI)-doped samples prepared under varying conditions, such as samples from sorption, hydration and diffusion experiments, and using different cementitious materials, such as crushed hydrated hardened cement paste (HCP) and calcium silicate hydrates (C-S-H). The samples had U(VI) loadings ranging from 1700 {mu}g/g to 45000 {mu}g/g. Applying principal component analysis (PCA) on 13 EXAFS spectra (each spectra corresponding to a minimum of five different scans) of the low loading samples, one single species is obtained indicating a similar U(VI) coordination environment for both HCP and C-S-H samples. This result confirms that C-S-H phases control the uptake of U(VI) in the complex cement matrix. The coordination environment structure of this species is similar to a U(VI) surface complex or to U(VI) in uranyl silicate minerals (two axial O atoms at 1.82 {+-} 0.02 A; four equatorial O atoms at 2.25 {+-} 0.01 A; one Si atom at 3.10 {+-} 0.03 A). At high U(VI) loading, PCA revealed a second U(VI) species, with a coordination environment similar to that of U(VI) in calcium uranate (two axial O atoms at 1.94 {+-} 0.04 A; five equatorial O atoms at 2.26 {+-} 0.01 A; four Ca atoms at 3.69 {+-} 0.05 A and five U atoms at 3.85 {+-} 0.04 A). This study suggest that, at low U(VI) loading, U(VI) is bound to C-S-H phases in HCP while at high U(VI) loading, the immobilization of U(VI) in cementitious materials is mainly controlled by the precipitation of a calcium uranate-type phase. (orig.)


    Experiments were made to determine the most efficient method of strain hardening railroad frog points in order to increase their fatigue resistance...Mechanical strain hardening with rolls 40 mm in diameter under a load of 8 tons produced in standard frogs cast from G13L high-manganese steel (AISI...Hadfield steel) a work-hardened surface layer 3-5 mm thick with a hardness of 340 HB. In other experiments, the frogs were hardened by exploding a

  18. Evaluation of Strain Hardening Parameters

    DING Zong-hai; Pavel Huml; YANG Wei


    The plane-strain compression test for three kinds of materials was carried out in a temperature range between room temperature and 400 ℃. The σ - ε curves and strain-hardening rate at different temperatures were simulated and a reasonable fit to the experimental data was obtained. A modified model created by data inference and computer simulation was developed to describe the strain hardening at a large deformation, and the predicted strain hardening are in a good agreement with that observed in a large range of stress. The influences of different parameters on strain hardening behaviour under large deformation were analysed. The temperature increase within the test temperatures for stainless steel 18/8 Ti results in dropping of flow stress and strain-hardening rate. For favourable γ-fibre texture to obtain high r, the cold rolling was applied at large reduction. In the experimental procedure, the X-ray diffraction test was carried out to compare the strain hardening and microstructure under large deformation for a bcc steel (low carbon steel SS-1142). The results indicate that the high strain-hardening rate possibly occurs when the primary slip plane {110} is parallel to the rolling plane and the strain-hardening rate decreases when lots of {110} plane rotate out from the orientation {110}∥RP.

  19. Aridity under conditions of increased CO2

    Greve, Peter; Roderick, Micheal L.; Seneviratne, Sonia I.


    A string of recent of studies led to the wide-held assumption that aridity will increase under conditions of increasing atmospheric CO2 concentrations and associated global warming. Such results generally build upon analyses of changes in the 'aridity index' (the ratio of potential evaporation to precipitation) and can be described as a direct thermodynamic effect on atmospheric water demand due to increasing temperatures. However, there is widespread evidence that contradicts the 'warmer is more arid' interpretation, leading to the 'global aridity paradox' (Roderick et al. 2015, WRR). Here we provide a comprehensive assessment of modeled changes in a broad set of dryness metrics (primarily based on a range of measures of water availability) over a large range of realistic atmospheric CO2 concentrations. We use an ensemble of simulations from of state-of-the-art climate models to analyse both equilibrium climate experiments and transient historical simulations and future projections. Our results show that dryness is, under conditions of increasing atmospheric CO2 concentrations and related global warming, generally decreasing at global scales. At regional scales we do, however, identify areas that undergo changes towards drier conditions, located primarily in subtropical climate regions and the Amazon Basin. Nonetheless, the majority of regions, especially in tropical and mid- to northern high latitudes areas, display wetting conditions in a warming world. Our results contradict previous findings and highlight the need to comprehensively assess all aspects of changes in hydroclimatological conditions at the land surface. Roderick, M. L., P. Greve, and G. D. Farquhar (2015), On the assessment of aridity with changes in atmospheric CO2, Water Resour. Res., 51, 5450-5463

  20. Radiation and chemical crosslinking promote strain hardening behavior and molecular alignment in ultra high molecular weight polyethylene during multi-axial loading conditions.

    Kurtz, S M; Pruitt, L A; Jewett, C W; Foulds, J R; Edidin, A A


    The mechanical behavior and evolution of crystalline morphology during large deformation of eight types of virgin and crosslinked ultra high molecular weight polyethylene (UHMWPE) were studied using the small punch test and transmission electron microscopy (TEM). We investigated the hypothesis that both radiation and chemical crosslinking hinder molecular mobility at large deformations, and hence promote strain hardening and molecular alignment during the multiaxial loading of the small punch test. Chemical crosslinking of UHMWPE was performed using 0.25% dicumyl peroxide (GHR 8110, GUR 1020 and 1050), and radiation crosslinking was performed using 150 kGy of electron beam radiation (GUR 1150). Crosslinking increased the ultimate load at failure and decreased the ultimate displacement of the polyethylenes during the small punch test. Crosslinking also increased the near-ultimate hardening behavior of the polyethylenes. Transmission electron microscopy was used to characterize the crystalline morphology of the bulk material, undeformed regions of the small punch test specimens, and deformed regions of the specimens oriented perpendicular and parallel to the punch direction. In contrast with the virgin polyethylenes, which showed only subtle evidence of lamellar alignment, the crosslinked polyethylenes exhibited enhanced crystalline lamellae orientation after the small punch test, predominantly in the direction parallel to the punch direction or deformation axis. Thus, the results of this study support the hypothesis that crosslinking promotes strain hardening during multiaxial loading because of increased resistance to molecular mobility at large deformations effected by molecular alignment. The data also illustrate the sensitivity of large deformation mechanical behavior and crystalline morphology to the method of crosslinking and resin of polyethylene.

  1. Effects of different tempers on precipitation hardening of 6000 series aluminium alloys

    LIU Hong; ZHAO Gang; LIU Chun-ming; ZUO Liang


    By means of Vickers hardness, mechanical property and formability tests, the effects of different tempers on precipitation hardening of 6000 series aluminium alloys for automotive body sheets were investigated. The results indicate that the short-time pre-aging at 170 ℃ makes for subsequent artificial aging precipitation hardening. With the increase of pre-aging time, the artificial aging hardenability increases. The aging hardening rate reaches the maximum when pre-aging time is up to 10 min, and then it decreases. The short-time pre-aging at 170 ℃ benefits sheets to obtain lower strength under delivery condition and consequently to improve stamping formability of automotive body sheets. The effects of different tempers on precipitation hardening are much more obvious than those of the alloying elements. It is a good treatment schedule to perform pre-aging for 5 min at 170 ℃ right after solution treatment.

  2. A hardenability test proposal

    Murthy, N.V.S.N. [Ingersoll-Rand (I) Ltd., Bangalore (India)


    A new approach for hardenability evaluation and its application to heat treatable steels will be discussed. This will include an overview and deficiencies of the current methods and discussion on the necessity for a new approach. Hardenability terminology will be expanded to avoid ambiguity and over-simplification as encountered with the current system. A new hardenability definition is proposed. Hardenability specification methods are simplified and rationalized. The new hardenability evaluation system proposed here utilizes a test specimen with varying diameter as an alternative to the cylindrical Jominy hardenability test specimen and is readily applicable to the evaluation of a wide variety of steels with different cross-section sizes.

  3. Post-machining thermal treatment after surface finishing of hardened steels: Kinetics of XRD line width reduction and improvement in rolling contact lifetime under mixed friction conditions

    Gegner, Juergen [SKF GmbH, Department of Material Physics, Ernst-Sachs-Str. 5, D-97424 Schweinfurt (Germany)


    Hard surface finishing represents the final manufacturing step for functional areas of machine elements in state-of-the-art production. Raceways of rolling bearing rings are ground and honed to the required low roughness. Plastic deformation is restricted to a narrow edge zone of the hardened steel. Reheating of the machined components below the martensite tempering or bainite transformation temperature results in a marked decrease of the XRD line width on the surface. The investigated samples are made of through-hardened standard bearing steel 100Cr6 (international denotation: SAE 52100). On the basis of a material model that explains the effect as a complex diffusion process of dislocational carbon segregation, i.e. static strain aging, the measured kinetics of the XRD line width reduction is simulated by an Arrhenius-type equation, which describes the rate-controlling reaction step of temper carbide dissolution. The formation of a small white-etching surface layer of around 1 um thickness by post-machining thermal treatment (PMTT) strongly supports this assumption. First rig tests suggest a considerable increase of the lifetime of Hertzian loaded elements that operate under heavy surface loading. PMTT performed in air leads to a beneficial nanoscaled oxide layer.

  4. The effect of cyclic hardening on fatigue properties of modified asphalt


    The phenomenon of cyclic hardening is observed in fatigue tests of modified asphalt controlled by low strain/stress level and it is not clear how the phenomenon affects the fatigue properties of binders. The special time weep tests were performed to investigate the point. Tests results indicate that the cyclic hardening is caused by the rearrangement of molecules in binders, and it can make the inner structure of binders getting stable and increase the fatigue properties of asphalt binders. But fatigue damage occurs when fatigue tests start, no matter the phenomenon of cyclic hardening happens or not. If the controlled load is low, the effect of rearrangement of molecules on material is beyond the effect of fatigue damage so that the cyclic hardening can be observed. When the load conditions get worse, the effect of slight fatigue damages produced in hardening stage will show.

  5. Industrial Hardening Demonstration.


    less severe conditions than thermal cracking (850’ - 950°F and 10 to 20 psi). Zeolitic or molecular sieve- base catalysts are used. Catalytic reforming...with Potential Industrial Hardening A-1 Participants B Post-Attack Petroleum Refining (and Production) B-1 from Crude Oil V List of Figures Number Page...the Key Worker Shelter 116 viii B-1 Proportions of the Products Obtained by Distillation B-2 of Six Crude Oils B-2 Generalized Flow Chart of the

  6. Increased spontaneous recovery with increases in conditioned stimulus alone exposures.

    Leung, Hiu Tin; Westbrook, R Frederick


    A series of experiments used the compound test procedure (Rescorla, 2002) to measure the size of spontaneous recovery of freezing responses by rats to a latently inhibited and/or extinguished conditioned stimulus (CS). The size of recovery was greater: to a pre-exposed and conditioned CS than to a CS just conditioned or just pre-exposed; to an extensively pre-exposed or extinguished CS than to a moderately pre-exposed or extinguished CS; and to a pre-exposed and extinguished CS than to a CS just pre-exposed or just extinguished. These results show that the size of recovery is proportional to the size of the depression produced by CS-alone exposures regardless of whether they occurred before, after, or both before and after conditioning. The results are discussed in terms of some contemporary models of recovery and of the inferences permitted by the use of the compound assessment technique.

  7. Deformation Wave Hardening of Metallic Materials

    A.V. Kirichek


    Full Text Available The article deals with the machine parts hardening by means of deformation waves generated by the impact system with a waveguide as an intermediary member. The conditions for the efficient use of impact energy for elastoplastic deformation of the processed material and creation of the deep hardened surface layer.

  8. Stress field near an interface edge of linear hardening materials

    许金泉; 付列东


    The elastic-plastic singular stress field near an interface edge of bounded linear hardening material is substantially as same as that of bonded elastic materials whose Young' s modulus and Poisson ratio are substituted by equivalent values, respectively. Further investigation by the elasto-plastic boundary element method (BEM) on the stress field near the interface edge showed that the stress field there can be divided into three regions: the domain region of the elastic-plastic singular stress field, the transitional region and the elastic region. The domain region of the elastic-plastic singular stress becomes larger with the increasing of the linear hardening coefficient. When the linear hardening coefficient decreases to a certain value, the effective stress in most of the yield zone equals approximately the yield stress. The stress distribution in the elastic region under small-scale yielding condition was also investigated.

  9. Stress field near an interface edge of linear hardening materials


    The elastic-plastic singular stress field near an interface edge of bounded linear hardening material is substantially as same as that of bonded elastic materials whose Young's modulus and Poisson ratio are substituted by equivalent values, respectively. Further investigation by the elasto-plastic boundary element method (BEM) on the stress field near the interface edge showed that the stress field there can be divided into three regions: the domain region of the elastic-plastic singular stress field, the transitional region and the elastic region. The domain region of the elastic-plastic singular stress becomes larger with the increasing of the linear hardening coefficient. When the linear hardening coefficient decreases to a certain value, the effective stress in most of the yield zone equals approximately the yield stress. The stress distribution in the elastic region under small-scale yielding condition was also investigated.

  10. Development of a Press-Hardened Steel Suitable for Thin Slab Direct Rolling Processing

    Lee, Jewoong; De Cooman, Bruno C.


    The thin slab casting and direct rolling process is a hot-rolled strip production method which has maintained commercial quality steel grades as a major material in many industrial applications due to its low processing cost. Few innovative products have however been developed specifically for production by thin slab direct rolling. Press hardening or hot press forming steel grades which are now widely used to produce structural automotive steel parts requiring ultra-high strength and formability may however offer an opportunity for thin slab direct rolling-specific ultra-high strength products. In this work, a newly designed press hardening steel grade developed specifically for thin slab direct rolling processing is presented. The press hardening steel has a high nitrogen content compared with press hardening steel grades produced by conventional steelmaking routes. Boron and titanium which are key alloying additions in conventional press hardening steel such as the 22MnB5 press hardening steel grade are not utilized. Cr is added in the press hardening steel to obtain the required hardenability. The properties of the new thin slab direct rolling-specific 22MnCrN5 press hardening steel grade are reviewed. The evolution of the microstructure and mechanical properties with increasing amounts of Cr additions from 0.6 to 1.4 wt pct and the effect of the cooling rate during die-quenching were studied by means of laboratory simulations. The selection of the optimum chemical composition range for the thin slab direct rolling-specific 22MnCrN5 steel in press hardening heat treatment conditions is discussed.

  11. [Hardening of dental instruments].

    Gerasev, G P


    The possibility of prolonging the service life of stomatological instruments by the local hardening of their working parts is discussed. Such hardening should be achieved by using hard and wear-resistant materials. The examples of hardening dental elevators and hard-alloy dental drills are given. New trends in the local hardening of instruments are the treatment of their working parts with laser beams, the application of coating on their surface by the gas-detonation method. The results of research work and trials are presented.

  12. Rapid cold hardening increases cold and chilling tolerances more than acclimation in the adults of the sycamore lace bug, Corythucha ciliata (Say) (Hemiptera: Tingidae).

    Ju, Rui-Ting; Xiao, Yu-Yu; Li, Bo


    The sycamore lace bug, Corythucha ciliata is a new, invasive pest of Platanus trees in China. Although C. ciliata is often subjected to acute low temperatures in early winter and spring in northern and eastern China, the cold tolerance of C. ciliata has not been well studied. The objectives of this study were to determine whether adults of C. ciliata are capable of rapid cold hardening (RCH), and to compare the benefits of RCH vs. cold acclimation (ACC) in the laboratory. When the adult females incubated at 26°C were transferred directly to the discriminating temperature (-12°C) for 2 h, survival was only 22%. However, exposure to 0°C for 4 h before transfer to -12°C for 2 h induced RCH, i.e., increased survival to 68%. RCH could also be induced by gradual cooling of the insects at rates between 0.1 and 0.25°C min(-1). The protection against cold shock obtained through RCH at 0°C for 4 h was lost within 1h if the adults were returned to 26°C before exposure to -12°C. Survival at both -12 and -5°C was greater for RCH-treated than for ACC-treated adults (for ACC, adults were kept at 15°C for 5 days), and the lethal temperature (2 h exposure) was lower for RCH-treated than for ACC-treated adults. The results suggest that RCH may help C. ciliata survive the acute low temperatures that often occur in early winter and early spring in northern and eastern China.

  13. The Tebuconazole-based Protectant of Seeds “Bunker” Induces the Synthesis of Dehydrins During Cold Hardening and Increases the Frost Resistance of Wheat Seedlings

    A.V. Korsukova


    Full Text Available Triazole derivatives are widely used in agriculture for seed protectant of cereals against seed and soil infection. Triazole derivatives can have an effect on the biochemical and physiological functions of plants. The tebuconazole-based protectant of seeds «Bunker» (content of tebuconazole 60 grams per liter, g/L is a systemic fungicide of preventive and therapeutic action. The effect of the seed treatment by «Bunker» preparation on the shoot growth and cell viability coleoptile, synthesis of dehydrins in shoots and frost resistance etiolated winter and spring wheat seedlings has been studied. It has been shown that treatment of winter and spring wheat seed by «Bunker» preparation induces similar concentration-dependent inhibition of the coleoptiles length. At the recommended dose (0,5 liter per tonne of seeds, L/t growth inhibition was 28 - 30%, at a concentration of 1 L/t – 33 - 36%, at a concentration of 1,5 L/t – 40 - 42%, at a concentration of 3 L/t – 43 - 47%, at a concentration of 4 L/t – 48 - 51% and at 5 L/t – 53 - 56%. The treatment of wheat seed by «Bunker» preparation had no phytotoxic effect on coleoptile cells in any of the studied concentrations, on the contrary, with increasing concentration of preparation observed the increase in cell viability, as measured by recovery of 2,3,5-triphenyltetrazolium chloride. We can assume that having retardant properties, tebuconazole not only inhibits the growth of plants, but also delays their aging. The treatment of seed protectant at a concentration of 1.5 L/t induced synthesis of the dehydrins with molecular masses about 19, 21, 22, 25 and 27 kD in winter wheat shoots and 18,6, 27 and 28,5 kD in spring wheat shoots during cold hardening. Among identified dehydrins the dehydrin of 27 kD is most significantly induced both in winter and spring wheat. The treatment of seed protectant «Bunker» in the same concentration increased the frost resistance of winter and spring wheat

  14. Laser Hardening of Metals

    Institute for Laser Physics; V.A.Serebryakov; K.V.Gratzianov; A.S.Eremenko; A.A.Timopheev; SPBSUITMO; M.V.Volkov


    Results of experiments on laser hardening of various materials with intensity 109~1010W/cm2 are represented. Nd:glass laser with energy up to 45J with a pulse duration ~30ns was used as a source of ra diation. Comparative researches of the laser peening for the various target areas are fulfilled. Results of laser hardening were determined by the microstructure analysis. The new approach to creation of the industrial laser for peening is discussed.




    Full Text Available This paper deals with the study of the performance of coated tools in machining hardening steel under dry conditions. This paper involves of machining AISI 4340 hardened steel using coated carbide tools is studied using full factorial experiments. Many parameters influence the quality of the products in hard turning process. The objective of this study is on the effect of the cutting conditions such as cutting velocity, feed, and depth of cut on the surface finish in machining AISI 4340 hardened steel. Machining of hardened steels has become an important manufacturing process, particularly in the automotive and bearing industries.

  16. Precipitation hardening in 350 grade maraging steel

    Viswanathan, U.K. (Bhabha Atomic Research Centre, Bombay, (India). Radiometallurgy Div.); Dey, G.K. (Bhabha Atomic Research Centre, Bombay, (India). Metallurgy Division); Asundi, M.K. (Government Colony, Bombay, (India))


    Evolution of microstructure in 350 grade commercial maraging steel has been examined. In the earlier stages of aging, the strengthening phases are formed by the heterogeneous precipitation, and these phases have been identified as intermetallic compounds of the Ni[sub 3] (Ti, Mo) and Fe[sub 2]Mo types. The kinetics of precipitation are studied in terms of the activation energy by carrying out isothermal hardness measurements of aged material. The mechanical properties in the peak-aged and overaged conditions were evaluated and the flow behavior examined. The overaging behavior of the steel has been studied and the formation of austenite of different morphologies identified. The crystallography of the austenite has been examined in detail. From the microstructural examination of peak-aged and deformed samples, it could be inferred that the dislocation-precipitate interaction is by precipitate shearing. Increased work hardening of the material in the overaged condition was suggestive of looping of precipitates by dislocations.

  17. Precipitation hardening in 350 grade maraging steel

    Viswanathan, U. K.; Dey, G. K.; Asundi, M. K.


    Evolution of microstructure in a 350 grade commercial maraging steel has been examined. In the earlier stages of aging, the strengthening phases are formed by the heterogeneous precipitation, and these phases have been identified as intermetallic compounds of the Ni3 (Ti, Mo) and Fe2Mo types. The kinetics of precipitation are studied in terms of the activation energy by carrying out isothermal hardness measurements of aged material. The mechanical properties in the peak-aged and overaged conditions were evaluated and the flow behavior examined. The overaging behavior of the steel has been studied and the formation of austenite of different morphologies identified. The crystallography of the austenite has been examined in detail. From the microstructural examination of peak-aged and deformed samples, it could be inferred that the dislocation-precipitate interaction is by precipitate shearing. Increased work hardening of the material in the overaged condition was suggestive of looping of precipitates by dislocations.

  18. Nitrogen nutrition and drought hardening exert opposite effects on the stress tolerance of Pinus pinea L. seedlings.

    Villar-Salvador, Pedro; Peñuelas, Juan L; Jacobs, Douglass F


    Functional attributes determine the survival and growth of planted seedlings in reforestation projects. Nitrogen (N) and water are important resources in the cultivation of forest species, which have a strong effect on plant functional traits. We analyzed the influence of N nutrition on drought acclimation of Pinus pinea L. seedlings. Specifically, we addressed if high N fertilization reduces drought and frost tolerance of seedlings and whether drought hardening reverses the effect of high N fertilization on stress tolerance. Seedlings were grown under two N fertilization regimes (6 and 100 mg N per plant) and subjected to three drought-hardening levels (well-watered, moderate and strong hardening). Water relations, gas exchange, frost damage, N concentration and growth at the end of the drought-hardening period, and survival and growth of seedlings under controlled xeric and mesic outplanting conditions were measured. Relative to low-N plants, high-N plants were larger, had higher stomatal conductance (27%), residual transpiration (11%) and new root growth capacity and closed stomata at higher water potential. However, high N fertilization also increased frost damage (24%) and decreased plasmalemma stability to dehydration (9%). Drought hardening reversed to a great extent the reduction in stress tolerance caused by high N fertilization as it decreased frost damage, stomatal conductance and residual transpiration by 21, 31 and 24%, respectively, and increased plasmalemma stability to dehydration (8%). Drought hardening increased tissue non-structural carbohydrates and N concentration, especially in high-fertilized plants. Frost damage was positively related to the stability of plasmalemma to dehydration (r = 0.92) and both traits were negatively related to the concentration of reducing soluble sugars. No differences existed between moderate and strong drought-hardening treatments. Neither N nutrition nor drought hardening had any clear effect on seedling

  19. Laser surface hardening of AISI H13 tool steel

    Jae-Ho LEE; Jeong-Hwan JANG; Byeong-Don JOO; Young-Myung SON; Young-Hoon MOON


    An attempt was made to improve the surface hardness and wear properties of AISI H13 tool steel through solid solution hardening and refinement of microstructures using a 200 W fiber laser as a heat generating source. The hardness of laser melted zone was investigated. In order to identify the effect of heat input on the laser melting zone, scanning conditions were controlled. The results show that, the hardness of as-received AISI H13 tool steel is approximately Hv 240, and the hardness after laser surface heat treatment is around Hv 480-510. The hardening depth and width are increased with the increase in the heat input applied. Application of experimental results will be considered in tooling industry.

  20. Hardening Azure applications

    Gaurav, Suraj


    Learn what it takes to build large scale, mission critical applications -hardened applications- on the Azure cloud platform. This 208 page book covers the techniques and engineering principles that every architect and developer needs to know to harden their Azure/.NET applications to ensure maximum reliability and high availability when deployed at scale. While the techniques are implemented in .NET and optimized for Azure, the principles here will also be valuable for users of other cloud-based development platforms. Applications come in a variety of forms, from simple apps that can be bui

  1. Tensile and Fatigue Testing and Material Hardening Model Development for 508 LAS Base Metal and 316 SS Similar Metal Weld under In-air and PWR Primary Loop Water Conditions

    Mohanty, Subhasish [Argonne National Lab. (ANL), Argonne, IL (United States); Soppet, William [Argonne National Lab. (ANL), Argonne, IL (United States); Majumdar, Saurin [Argonne National Lab. (ANL), Argonne, IL (United States); Natesan, Ken [Argonne National Lab. (ANL), Argonne, IL (United States)


    This report provides an update on an assessment of environmentally assisted fatigue for light water reactor components under extended service conditions. This report is a deliverable in September 2015 under the work package for environmentally assisted fatigue under DOE’s Light Water Reactor Sustainability program. In an April 2015 report we presented a baseline mechanistic finite element model of a two-loop pressurized water reactor (PWR) for systemlevel heat transfer analysis and subsequent thermal-mechanical stress analysis and fatigue life estimation under reactor thermal-mechanical cycles. In the present report, we provide tensile and fatigue test data for 508 low-alloy steel (LAS) base metal, 508 LAS heat-affected zone metal in 508 LAS–316 stainless steel (SS) dissimilar metal welds, and 316 SS-316 SS similar metal welds. The test was conducted under different conditions such as in air at room temperature, in air at 300 oC, and under PWR primary loop water conditions. Data are provided on materials properties related to time-independent tensile tests and time-dependent cyclic tests, such as elastic modulus, elastic and offset strain yield limit stress, and linear and nonlinear kinematic hardening model parameters. The overall objective of this report is to provide guidance to estimate tensile/fatigue hardening parameters from test data. Also, the material models and parameters reported here can directly be used in commercially available finite element codes for fatigue and ratcheting evaluation of reactor components under in-air and PWR water conditions.

  2. Effect of strain rate on bake hardening response of BH220 steel

    Das Anindya


    Full Text Available This study aims at understanding the bake hardening ability of ultra low carbon BH220 steel at different strain rates. The as-received material has been pre-strained to four different levels and then deformed in tension under (a as pre-strained state and (b after baking at 170 ∘C for 20 minutes, at three different strain rates of 0.001, 0.1 and 100/s. In both the conditions, yield stress increased with pre-strain and strain rate, but bake hardening ability was found to decrease when strain rate was increased. The strain rate sensitivity of the material was also found to decrease with bake hardening. Generation of dislocation forests and their subsequent immobility during baking treatment enables them to act as long range obstacles during further deformation. At higher strain rates, less amount of dislocations are produced which can interact with themselves and produce hardening, because of which bake hardening ability and the strain rate drops. A dislocation based strengthening model, as proposed by Larour et al. 2011 [7], was used to predict the yield stress values obtained at different conditions. The equation produced excellent co-relation with the experimental data.

  3. Effect of Overaging on Solute Distributions and Bake Hardening Phenomenon in Bake Hardening Steels%Effect of Overaging on Solute Distributions and Bake Hardening Phenomenon in Bake Hardening Steels

    WANG Hua; SHI Wen; HE Yan-lin; LU Xiao-gang; LI Lin


    Specimens of two different kinds of bake hardening steels (BH-Mn and BH-P) were prepared and treated with different annealing processes (water quenching and overaging). A novel technique of three dimensional atom probe was used to investigate solute distributions in these steels. The results indicate that C concentration decreases, whereas V increases during overaging in both bake hardening steels. The conclusion that no vanadium carbides pre- cipitate during the overaging is therefore originally obtained by microanalysis in bake hardening steels. Moreover, bake hardening values of all the specimens were tested by tensile experiments with 2 0/~ pre-deformation. However, those of overaged specimens were further measured with higher levels of pre-deformation because no bake hardening phenomenon was present at 2% pre-deformation. As the pre-deformation increases from 2% to 6% and 8%, both overaged steels show bake hardening values, and the value data are almost the same.

  4. Laser Surface Hardening of 9CrSi Steel


    The effects of laser hardening parameters such as beam power, beam diameter and scanning rate on microstructureand hardness of 9CrSi steel were investigated. The microstructure of the surface layer of 9CrSi steel was changed frompearlite to martensite, retained austenite and carbide by laser hardening. The depth of the hardened layer increasedwith increasing laser energy density and the surface hardeness increased by 3~5 times as high as the untreated steel.The laser hardened surface had good wear resistance due to martensite and carbide in the surface layer. The wearmode at Iow speed was abrasive, while the wear mode at high speed was adhesive.

  5. Concrete, hardened: Self desiccation

    Hansen, Ernst Jan De Place; Hansen, Kurt Kielsgaard; Persson, Bertil


    The test method covers the determination of internal relative humidity (RH) in hardened concrete and cement mortar using RH instruments. The determination of RH is done on crushed samples of concrete or cement motar. This test method is only for measuring equipment which gives off or takes up...

  6. 40 CFR 141.625 - Conditions requiring increased monitoring.


    ... 40 Protection of Environment 22 2010-07-01 2010-07-01 false Conditions requiring increased monitoring. 141.625 Section 141.625 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Stage 2 Disinfection Byproducts Requirements § 141.625 Conditions...


    HESS, F


    A new viscoplastic model for the plastic stress-strain behaviour of f.c.c. metals is presented. In this model the strain hardening results from increasing dislocation densities. The observed stagnation of strain hardening after strain reversals is explained by a lowering of the increase in dislocati

  8. Improvement of a chain-hardening furnace by computational fluid dynamics (CFD) simulation

    Sala, J.M.; Eguia, J.J. [E.T.S. Ingenieros Industriales, Bilbao (Spain); Gonzalez, L.M. Lopez; Vicuna, J.E.; Juarez, M.C.; Domenech, J. [Universidad de La Rioja, Escuela Tecnica Superior de Ingenieria Industrial de Logrono, Logrono (La Rioja) (Spain); Miguez, J.L. [E.T.S. de Ingenieros Industriales, Lagoas-Marcosende, Vigo (Spain)


    Hardening heat-treatment is an important operation in the fabrication of large chains for both the shipping industry and anchorage of offshore oil-platforms. This paper presents the outcome of an investigation that led to the introduction of modifications in a hardening furnace resulting in a substantial improvement and largely eliminating the problem of gradual cooling of the chain before immersion in the water-quenching tank. Comparing this with the present operating conditions, it can be concluded that redirecting the gas flow increases the gas temperature in the lower part of the furnace, which changes the chain's temperature-distribution accordingly. (Author)

  9. RHOBOT: Radiation hardened robotics

    Bennett, P.C.; Posey, L.D. [Sandia National Labs., Albuquerque, NM (United States)


    A survey of robotic applications in radioactive environments has been conducted, and analysis of robotic system components and their response to the varying types and strengths of radiation has been completed. Two specific robotic systems for accident recovery and nuclear fuel movement have been analyzed in detail for radiation hardness. Finally, a general design approach for radiation-hardened robotics systems has been developed and is presented. This report completes this project which was funded under the Laboratory Directed Research and Development program.

  10. Grind hardening process

    Salonitis, Konstantinos


    This book presents the grind-hardening process and the main studies published since it was introduced in 1990s.  The modelling of the various aspects of the process, such as the process forces, temperature profile developed, hardness profiles, residual stresses etc. are described in detail. The book is of interest to the research community working with mathematical modeling and optimization of manufacturing processes.

  11. Nuclear effects hardened shelters

    Lindke, Paul


    The Houston Fearless 76 Government Projects Group has been actively engaged for more than twenty-five years as a sub-contractor and currently as a prime contractor in the design, manufacture, repair and logistics support of custom mobile ground stations and their equipment accommodations. Other associated products include environmental control units (ECU's), mobilizers for shelters and a variety of mobile power generation units (MPU's). Since 1984, Houston Fearless 76 has designed and manufactured four 8' x 8' x 22' nuclear hardened mobile shelters. These shelters were designed to contain electronic data processing/reduction equipment. One shelter is currently being operated by the Air Force as a Defense Intelligence Agency (DIA) approved and certified Special Corrpartmented Information Facility (SCIF). During the development and manufacturing process of the shelters, we received continual technical assistance and design concept evaluations from Science Applications International Corporation (SAIC) Operations Analysis and Logistics Engineering Division and the Nondestructive Inspection Lab at McClellan AFB. SAIC was originally employed by the Air Force to design the nuclear hardening specifications applied to these shelters. The specific levels of hardening to which the shelters were designed are classified and will not be mentioned during this presentation.

  12. Differential hardening in IF steel - Experimental results and a crystal plasticity based model

    Mulder, J.; Eyckens, P.; van den Boogaard, Antonius H.; Hora, P.


    Work hardening in metals is commonly described by isotropic hardening, especially for monotonically increasing proportional loading. The relation between different stress states in this case is determined by equivalent stress and strain definitions, based on equal plastic dissipation. However,

  13. Theoretical Studies of Laws Nanostructuring and Heterogeneous Hardening of Steel Samples by Wave Intensive Plastic Deformation

    A.V. Kirichek


    Full Text Available Theoretical studies and calculations, allowing to define the required parameters of the wave deformation hardening, are performed in order to obtain heterogeneous hardened surface layer in steel samples. The conditions for the effective use of impact energy for elastic-plastic deformation of the processed material and the establishment of a deep hardened surface layer are revealed.

  14. Interaction between alloying and hardening of cast iron surface

    刘政军; 郝雪枫; 傅迎庆; 牟力军


    To improve wear resistance of surface will increase the service life of gray cast iron directly. This paper presents that gray cast iron surface coated with alloy powder is locally remelted by TIG arc to increase the wear resistance. The influences of arc current and scanning rate etc on surface properties are found. Under different conditions, the microstructure, hardness and wear resistance of remelted layer are analyzed and measured. The results indicate that the gray cast iron surface can be strengthened by TIG arc local remelting treatment. Especially, surface alloying hardening effect is best and surface properties are improved remarkably.

  15. "Work-Hardenable" ductile bulk metallic glass.

    Das, Jayanta; Tang, Mei Bo; Kim, Ki Buem; Theissmann, Ralf; Baier, Falko; Wang, Wei Hua; Eckert, Jürgen


    Usually, monolithic bulk metallic glasses undergo inhomogeneous plastic deformation and exhibit poor ductility (< 1%) at room temperature. We present a new class of bulk metallic glass, which exhibits high strength of up to 2265 MPa together with extensive "work hardening" and large ductility of 18%. Significant increase in the flow stress was observed during deformation. The "work-hardening" capability and ductility of this class of metallic glass is attributed to a unique structure correlated with atomic-scale inhomogeneity, leading to an inherent capability of extensive shear band formation, interactions, and multiplication of shear bands.

  16. On The Enhancement of Wear Resistance of Hardened Carbon Tool Steel (AISI 1095) With Cryogenic Quenching

    V.Soundararajan; N.Alagurmurthi; K.Palaniradja


    Many experimental investigations reveal that it is very difficult to have a completely martensitic structure by any hardening process. Some amount of austenite is generally present in the hardened steel. This austenite existing along with martensite is normally referred as the retained austenite. The presence of retained austenite greatly reduces the mechanical properties and such steels do not develop maximum hardness even after cooling at rates higher than the critical cooling rates.Strength can be improved in hardened steels containing retained austenite by a process known as cryogenic quenching.Untransformed austenite is converted into martensite by this treatment. This conversion of retained austenite into martensite results in increased hardness, wear resistance and dimensional stability of steel. Wear can be defined as the progressive loss of materials from the operating surface of a body occurring as a result of relative motion at the surface. Hardness, load,speed, surface roughness, temperature are the major factors which influences wear. Many studies on wear indicate that increasing hardness decreases the wear of a material. With this in mind, to study the surface wear on a surface modified(Cryogenic treated) steel material an attempt has been made in this paper. In this study as a Part -I Hardening was carried out on carbon tool steel (AISI 1095) of different L/D ratio with conventional quenchants like purified water, aqueous solution and Hot mineral oil. As a Part -Ⅱ hardening was followed by quenching was carried out as said in Part- I and the hardened specimen were quenched in liquid Nitrogen which is at sub zero condition. The specimens were tested for its microstructure, hardness and wear loss. The results were compared and analyzed. The alloying elements increases the content of retained austenite hence the material used was AISI1095 (Carbon 0.9%, Si 0.2%, Mn0.4% and the rest Iron)

  17. Increased radiation tolerance of mouse tongue epithelium after local conditioning

    Doerr, W.; Kummermehr, J. (Gesellschaft fuer Strahlen- und Umweltforschung mbH Muenchen, Neuherberg (Germany). Abt. fuer Strahlenbiologie)


    The effect of local stimulation on mitotic activity and radiation tolerance was studied in mouse tongue mucosa. Silver nitrate solution (0.5-20%) was used for local conditioning. Silver nitrate conditioning did not alter the radiosensitivity of the epithelium to single local doses, but shortened the latency to denudation from 11 to 8 days. In contrast, a clear increase in tolerance to fractionated irradiation, delivering 5x2.5, 5x3.5, 5x4.5 Gy or 3x5.2 Gy in 7 days, was observed, equivalent to about four, two, one and two extra dose fractions. This approach may be a suitable way to increase radiation tolerance of oral mucosa in clinical radiotherapy. (author).

  18. Cosmic Ray Helium Hardening

    Ohira, Yutaka


    Recent observations by CREAM, ATIC-2 and PAMELA experiments suggest that (1) the spectrum of cosmic ray (CR) helium is harder than that of CR proton below the knee $10^15 eV$ and (2) all CR spectra become hard at $\\gtrsim 10^{11} eV/n$. We propose a new picture that higher energy CRs are generated in more helium-rich region to explain the hardening (1) without introducing different sources for CR helium. The helium to proton ratio at $\\sim 100$ TeV exceeds the Big Bang abundance $Y=0.25$ by several times, and the different spectrum is not reproduced within the diffusive shock acceleration theory. We argue that CRs are produced in the chemically enriched region, such as a superbubble, and the outward-decreasing abundance naturally leads to the hard spectrum of CR helium when escaping from the supernova remnant (SNR) shock. We provide a simple analytical spectrum that also fits well the hardening (2) because of the decreasing Mach number in the hot superbubble with $\\sim 10^6$ K. Our model predicts hard and con...

  19. Effect of hardening methods of moulding sands with water glass on structure of bonding bridges

    M. Stachowicz


    Full Text Available Research on influence of hardening methods on structure of bonding bridges in moulding sands with sodium water glass is presented.Moulding sands with addition of 2.5 % of binder with molar module 2.0 were hardened with CO2 and dried in traditional way or hardenedwith microwaves. It was proved that the hardening method affects structure of bonding bridges, correlating with properties of the hardened moulding sands. It was found that strength of the moulding sands hardened with microwaves for 4 min is very close to that measured after traditional drying at 110 °C for 120 min. So, application of microwave hardening ensures significant shortening of the process time to the value comparable with CO2 hardening but guaranteeing over 10-fold increase of mechanical properties. Analysis of SEM images of hardened moulding sands permitted explaining differences in quality parameters of moulding sands by connecting them with structure of the created bonding bridges.

  20. Atomic force microscopy of swelling and hardening of intact erythrocytes fixed on substrate

    Khalisov, M. M.; Timoshchuk, K. I.; Ankudinov, A. V.; Timoshenko, T. E.


    Peak force measurements with the aid of atomic force microscopy are used to quantitatively map nanomechanical properties of intact erythrocytes of rats under conditions that are close to physiological conditions. Erythrocytes that are immobilized on the substrate preliminary processed using poly-L-lysine predominantly exhibit plane shape. However, cells may also exhibit stepwise transformation to semispherical objects with an increase in volume and hardening. Possible reasons for such transformations are discussed.

  1. Influence of Cultivar on the Postharvest Hardening of Trifoliate Yam (Dioscorea dumetorum Tubers

    Christian Siadjeu


    Full Text Available The influence of cultivar on the postharvest hardening of Dioscorea dumetorum tubers was assessed. 32 cultivars of D. dumetorum tubers were planted in April 2014, harvested at physiological maturity, and stored under prevailing tropical ambient conditions (19–28°C, 60–85% RH for 0, 5, 14, 21, and 28 days. Samples were evaluated for cooked hardness. Results showed that one cultivar, Ibo sweet 3, was not affected by the hardening phenomenon. The remaining 31 were all subject to the hardening phenomenon at different degree. Cooked hardness increased more rapidly in cultivars with many roots on the tuber surface compared to cultivars with few roots on the tuber surface. When both the characteristics flesh colour and number of roots on tuber surface were associated, cooked hardness in cultivars with yellow flesh and many roots increased more rapidly than in cultivars with white flesh and many roots, whereas cooked hardness in cultivars with yellow flesh and few roots increased more slowly than in cultivars with white flesh and few roots. Accessions collected in high altitude increased more rapidly compared to accessions collected in low altitude. The cultivar Ibo sweet 3 identified in this study could provide important information for breeding program of D. dumetorum against postharvest hardening phenomenon.

  2. Phase transformations in titanium alloys hardened by rapid heating

    Gridnev, V.N.; Ivasishin, O.M.; Oshkaderov, S.P.; Smirnov, A.M. (AN Ukrainskoj SSR, Kiev. Inst. Metallofiziki)

    Features of phase transformations in titanium alloys, which subjected to hardening by rapid heating, are studied. The model for mathematical description of ..cap alpha..+..beta.. ..-->.. ..beta..- transformation under the conditions of continuous heating with different rate, is proposed. The increase of the polymorphic transformation temperature with the heating rate, is predicted and confirmed experimentally. Under certain conditions this fact can result in a two-stage process, of ..cap alpha..+..beta.. ..-->.. ..beta..-transformation, which begins according to difussion mechanism, and completes according to the non-diffusion one. It is shown, that ..cap alpha..+..beta.. ..-->.. ..beta..-transformation under non-equilibrium conditions is followed by appearing of concentration non-uniformity in reacting phases, that essentially affects the grain and intragranular structure of hardened alloys, and their phase composition. Variants of phase composition of the alloys of different classes quenched after rapid heating in the ..beta..-field, are analyzed. Possible aspects of the effect of increased heating rates on the ageing process are considered.

  3. Tensile Strain Hardening Behavior and Fractography of Superalloy GH39

    WANG Hui


    Full Text Available The strain hardening behaviour and fractography of superalloy GH39 was investigated by tensile test at different strain rates. Results indicate that strain hardening behaviours are different during the deformation process. True stress-strain curve obeys the Hollomon relationship partly. The strain hardening exponentn in this stage is constant in the initial plastic stage. However, the value of n increased with true strain ε increasing when true strain is between 0.014 and 0.13. A lot of deformation twinning can be found, the twins and dislocations worked together to increase the value of n. The strain hardening exponent is increased lightly with the strain rate increasing, SEM observations show that in the case of low strain rate, the fracture mode is typical ductile, but there is a tendency from ductile to brittle fracture with increasing the strain rate.

  4. Development of Press Hardening Steel with High Resistance to Hydrogen Embrittlement

    Bian, Jian; Mohrbacher, Hardy; Lu, Hongzhou; Wang, Wenjun

    Press hardening has become the state-of-art technology in the car body manufacturing to enhance safety standard and to reduce CO2 emission of new vehicles. However the delayed cracking due to hydrogen embrittlement remains to be a critical issue. Generally press hardening steel is susceptible to hydrogen embrittlement due to ultra-high strength and martensitic microstructure. The hydrogen charging tests clearly demonstrate that only a few ppm of diffusible hydrogen is sufficient to cause such embrittlement. Currently the hydrogen embrittlement cannot be detected in the press hardened components and the embitteled components could collapse in the crash situation with fatal consequences arisen through dramatic loss in both strength and ductility. This paper introduces a new metallurgical solution to increase the resistance to hydrogen embrittlement of conventional press hardening steel based on 22MnB5 by Nb microalloying. In the hydrogen embrittlement and permeation tests the impact of Nb microalloying on the hydrogen embrittlement behavior was investigated under different hydrogen charging conditions and constant load. The test results revealed that Nb addition increases the resistance to hydrogen embrittlement due to reduced hydrogen diffusivity. The focus of this paper is to investigate the precipitation behavior of microalloying elements by using TEM and STEM and to find out the mechanisms leading to higher performance against hydrogen embrittlement of Nb alloyed steels.


    P. V. Bech


    Full Text Available Purpose. In this paper it is necessary to analyze the types of competition in the transport market in order to find ways to improve the competitiveness of railway transport and to determine the ensuring equal conditions for all market participants by eliminating discrimination in competition. Methodology. Analysis of recent research and publications on the subject was held by the authors. The question of the development of competition, increased competitiveness in railway transport was investigated. Attention is drawn to the fact that due to the decline in traffic volumes on all modes of transport competition may significantly change the usual sphere the effective use of different modes of transport. Every mode of transport occupies a particular segment of the transport market, taking into account its technical and economic features, weakly competing, and in some cases do not compete with each other (except the road transport. However, it is entirely possible competition inside these segments.Findings. The problems of management of competitiveness, including the transport market, which required extensive analysis and serious scientific study, were identified. Originality. As a result of this work the features of transport and production of transport in modern conditions were structured. The dependences of passenger turnover and freight turnover by mode of transport over the past decade were shown. The question of additional profits by providing the cargo owners a range of service was examined. The optimal combination of cost and quality of such services at each transportation company promotes increasing its competitive status. Practical value. Competition between enterprises of the industry put the aim of improving the competitiveness of not only railway subsystems directly involved in technology movement of cargoes and the movement of passengers, but also the organization of infrastructure in the first place – subsystems to expand services

  6. Mitochondrial biogenesis of astrocytes is increased under experimental septic conditions

    Wang Yang; Chen Zhijiang; Zhang Yu; Fang Suzhen; Zeng Qiyi


    Background Mitochondrial dysfunction has been reported to be one of the contributing factors of sepsis-associated encephalopathy (SAE).Mitochondrial biogenesis controls mitochondrial homeostasis and responds to changes in cellular energy demand.In addition,it is enhanced or decreased due to mitochondrial dysfunction during SAE.The aim of this study was to explore the changes of mitochondrial biogenesis of astrocytes under septic conditions.Methods Lipopolysaccharide (LPS; 50 ng/ml) and interferon-γ (IFN-γ; 200 U/ml) were incubated with astrocytes to model the effects of a septic insult on astrocytes in vitro.The mitochondrial ultrastructure and volume density were evaluated by transmission electron microscopy.Intracellular adenosine triphosphate (ATP) levels were detected by the firefly luciferase system.The expression of protein markers of mitochondrial biogenesis and the binding ability of mitochondrial transcription factor A (TFAM) were determined by western blot and electrophoretic mobility shift assays,respectively.The mitochondrial DNA (mtDNA) content was detected by real-time polymerase chain reaction.Results The number of mildly damaged mitochondria was found to be significantly greater after treatment for 6 hours,as compared with at 0 hour (P<0.05).The mitochondrial volume density was significantly elevated at 24 hours,as compared with at 0 hour (P<0.05).The ATP levels at 6 hours,12 hours,and 24 hours were significantly greater than those at 0 hour (P<0.05).The protein markers of mitochondrial biogenesis were significantly increased at 6 hours and 12 hours,as compared with at 0 hour (P<0.05).The TFAM binding activity was not significantly changed among the four time points analyzed.The mtDNA contents were significantly increased at 12 hours and 24 hours,as compared with at 0 hour (P<0.05).Conclusions Under septic conditions,mitochonddal biogenesis of astrocytes increased to meet the high-energy demand and to promote mitochondrial recovery

  7. Assessment of the microstructure and torsional fatigue performance of an induction hardened vanadium microalloyed medium-carbon steel

    Rothleutner, Lee M.

    -martensitic transformation products in the induction-hardened case. In the total case region, vanadium reduced the total case depth by inhibiting austenite formation at low austenitizing temperatures; however, the non-martensitic constituents in the case microstructure and the reduced total case depth of the vanadium microalloyed steel did not translate directly to a degradation of torsional fatigue properties. In general, vanadium microalloying was not found to affect torsional fatigue performance significantly with one exception. In the 25 pct effective case depth condition, the 10V45 steel had a ~75 pct increase in fatigue life at all shear stress amplitudes when compared to the 1045 steel. The improved fatigue performance is likely a result of the significantly higher case hardness this condition exhibited compared to all other conditions. The direct influence of vanadium on the improved fatigue life of the 25 pct effective case depth condition is confounded with the slightly higher carbon content of the 10V45 steel. In addition, the 10V45 conditions showed a consistently higher case hardness than the in 1045 conditions. The increased hardness of the 10V45 steel did not increase the compressive residual stresses at the surface. Induction hardening parameters were more closely related to changes in residual stress than vanadium microalloying additions. Torsional fatigue data from the current study as well as from literature were used to develop an empirical multiple linear regression model that accounts for case depth as well as carbon content when predicting torsional fatigue life of induction hardened medium-carbon steels.

  8. Porosity and mechanically optimized PLGA based in situ hardening systems.

    Schloegl, W; Marschall, V; Witting, M Y; Volkmer, E; Drosse, I; Leicht, U; Schieker, M; Wiggenhorn, M; Schaubhut, F; Zahler, S; Friess, W


    Goal of the present study was to develop and to characterize in situ-hardening, porous PLGA-based systems for their future application as bone grafting materials. Therefore, we investigated the precipitation behavior of formulations containing PLGA and a water-miscible solvent, DMSO, PEG 400, and NMP. To increase porosity, a pore forming agent (NaCMC) was added and to enhance mechanical properties of the system, an inorganic filler (α-TCP) was incorporated. The behavior upon contact with water and the influence of the prior addition of aqueous media on the morphology of the corresponding hardened implants were investigated. We proved cell-compatibility by live/dead assays for the hardened porous polymer/ceramic-composite scaffolds. The IsHS formulations can therefore be used to manufacture hardened scaffolds ex vivo by using molds with the desired shape and size. Cells were further successfully incorporated into the IsHS by precultivating the cells on the α-TCP-powder prior to their admixing to the formulation. However, cell viability could not be maintained due to toxicity of the tested solvents. But, the results demonstrate that in vivo cells should well penetrate, adhere, and proliferate in the hardened scaffolds. Consequently, we consider the in situ hardening system being an excellent candidate as a filling material for non-weight-bearing orthopedic indications, as the resulting properties of the hardened implant fulfill indication-specific needs like mechanical stability, elasticity, and porosity.

  9. Surface modification on PMMA : PVDF polyblend: hardening under chemical environment

    R Bajpai; V Mishra; Pragyesh Agrawal; S C Datt


    The influence of chemical environment on polymers include the surface alteration as well as other deep modifications in surface layers. The surface hardening, as an effect of organic liquids on poly(methyl methacrylate): poly(vinylidene fluoride) (PMMA: PVDF), which is one of the few known miscible blends, has been detected using microhardness testing. Organic liquids like acetone, toluene, xylene and benzene were introduced on the surface of blend specimens for different durations. Vickers microhardness (v) was measured for treated and untreated specimens. The study reveals both hardening and plasticization of specimens at different exposure times. The degree of surface hardening is maximum under acetone treatment. All the specimens exhibit surface hardening at an exposure time of 1 h with all the four liquids. This feature is prominent with longer exposures for specimens with increasing content of PVDF. However, the degree of hardening decreases with the time of exposure in the respective environments. In general, acetone and toluene impart surface hardening, whereas, xylene and benzene soften the specimen. PMMA: PVDF (83 : 17) blend exhibits surface hardening under all the four treatments when compared with the respective untreated specimens.

  10. System-Level Radiation Hardening

    Ladbury, Ray


    Although system-level radiation hardening can enable the use of high-performance components and enhance the capabilities of a spacecraft, hardening techniques can be costly and can compromise the very performance designers sought from the high-performance components. Moreover, such techniques often result in a complicated design, especially if several complex commercial microcircuits are used, each posing its own hardening challenges. The latter risk is particularly acute for Commercial-Off-The-Shelf components since high-performance parts (e.g. double-data-rate synchronous dynamic random access memories - DDR SDRAMs) may require other high-performance commercial parts (e.g. processors) to support their operation. For these reasons, it is essential that system-level radiation hardening be a coordinated effort, from setting requirements through testing up to and including validation.

  11. Properties of sodium silicate bonded sand hardened by microwave heating

    Wang Jina; Fan Zitian; Zan Xiaolei; Pan Di


    The sodium silicate bonded sand hardened by microwave heating has many advantages,such as low sodium silicate adding quantity,fast hardening speed,high room temperature strength,good collapsibility and certain surface stability. However,it has big moisture absorbability in the air,which would lead to the compression strength and the surface stability of the sand molds being sharply reduced. In this study,the moisture absorbability of the sodium silicate bonded sand hardened by microwave heating in different humidity conditions and the effect factors were investigated. Meanwhile,the reasons for the big moisture absorbability of the sand were analyzed.Some measures to overcome the problems of high moisture absorbability,bad surface stability and sharply reducing strength in the air were discussed. The results of this study establish the foundation of green and clean foundry technology based on the microwave heating hardening sodium silicate sand process.


    A. I. Mihluk


    Full Text Available The new approach for technology of volumetric – superficial hardening of gear details of the back axle made of steel lowered harden ability is offered. This approach consisting in formation of intense – hardened condition on all surface of a detail.

  13. Contact allergy to epoxy hardeners.

    Aalto-Korte, Kristiina; Suuronen, Katri; Kuuliala, Outi; Henriks-Eckerman, Maj-Len; Jolanki, Riitta


    Diglycidylether of bisphenol A resin is the most important sensitizer in epoxy systems, but a minority of patients develop concomitant or solitary contact allergy to epoxy hardeners. At the Finnish Institute of Occupational Health, several in-house test substances of epoxy hardeners have been tested in a special epoxy compound patch test series. To analyse the frequency and clinical relevance of allergic reactions to different epoxy hardeners. Test files (January 1991 to March 2013) were screened for contact allergy to different epoxy hardeners, and the clinical records of patients with allergic reactions were analysed for occupation, concomitant allergic reactions, and exposure. The most commonly positive epoxy hardeners were m-xylylenediamine (n = 24), 2,4,6-tris-(dimethylaminomethyl)phenol (tris-DMP; n = 14), isophorone-diamine (n = 12), and diethylenetriamine (n = 9). Trimethylhexamethylenediamine (n = 7), tetraethylenepentamine (n = 4), and triethylenetetramine (n = 2) elicited some reactions, although most patients were found to have no specific exposure. Allergic reactions to hexamethylenetetramine, dimethylaminopropylamine and ethylenediamine dihydrochloride were not related to epoxy products. Tris-DMP is an important sensitizer in epoxy hardeners, and should be included in the patch test series of epoxy chemicals. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  14. Devising Strain Hardening Models Using Kocks–Mecking Plots—A Comparison of Model Development for Titanium Aluminides and Case Hardening Steel

    Markus Bambach


    Full Text Available The present study focuses on the development of strain hardening models taking into account the peculiarities of titanium aluminides. In comparison to steels, whose behavior has been studied extensively in the past, titanium aluminides possess a much larger initial work hardening rate, a sharp peak stress and pronounced softening. The work hardening behavior of a TNB-V4 (Ti–44.5Al–6.25Nb–0.8Mo–0.1B alloy is studied using isothermal hot compression tests conducted on a Gleeble 3500 simulator, and compared to the typical case hardening steel 25MoCrS4. The behavior is analyzed with the help of the Kocks-Mecking plots. In contrast to steel the TNB-V4 alloy shows a non-linear course of θ (i.e., no stage-III hardening initially and exhibits neither a plateau (stage IV hardening nor an inflection point at all deformation conditions. The present paper describes the development and application of a methodology for the design of strain hardening models for the TNB-V4 alloy and the 25CrMoS4 steel by taking the course of the Kocks-Mecking plots into account. Both models use different approaches for the hardening and softening mechanisms and accurately predict the flow stress over a wide range of deformation conditions. The methodology may hence assist in further developments of more sophisticated physically-based strain hardening models for TiAl-alloys.

  15. Strain Hardening of Polymer Glasses: Entanglements, Energetics, and Plasticity

    Hoy, Robert S.; Robbins, Mark O.


    Simulations are used to examine the microscopic origins of strain hardening in polymer glasses. While stress-strain curves for a wide range of temperature can be fit to the functional form predicted by entropic network models, many other results are fundamentally inconsistent with the physical picture underlying these models. Stresses are too large to be entropic and have the wrong trend with temperature. The most dramatic hardening at large strains reflects increases in energy as chains are ...

  16. Cross-tolerance effects due to adult heat hardening, desiccation and starvation acclimation of tropical drosophilid-Zaprionus indianus.

    Kalra, Bhawna; Tamang, Aditya Moktan; Parkash, Ravi


    Some insect taxa from polar or temperate habitats have shown cross-tolerance for multiple stressors but tropical insect taxa have received less attention. Accordingly, we considered adult flies of a tropical drosophilid-Zaprionus indianus for testing direct as well as cross-tolerance effects of rapid heat hardening (HH), desiccation acclimation (DA) and starvation acclimation (SA) after rearing under warmer and drier season specific simulated conditions. We observed significant direct acclimation effects of HH, DA and SA; and four cases of cross-tolerance effects but no cross-tolerance between desiccation and starvation. Cross-tolerance due to heat hardening on desiccation showed 20% higher effect than its reciprocal effect. There is greater reduction of water loss in heat hardened flies (due to increase in amount of cuticular lipids) as compared with desiccation acclimated flies. However, cross-tolerance effect of SA on heat knockdown was two times higher than its reciprocal. Heat hardened and desiccation acclimated adult flies showed substantial increase in the level of trehalose and proline while body lipids increased due to heat hardening or starvation acclimation. However, maximum increase in energy metabolites was stressor specific i.e. trehalose due to DA; proline due to HH and total body lipids due to SA. Rapid changes in energy metabolites due to heat hardening seem compensatory for possible depletion of trehalose and proline due to desiccation stress; and body lipids due to starvation stress. Thus, observed cross-tolerance effects in Z. indianus represent physiological changes to cope with multiple stressors related to warmer and drier subtropical habitats. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Dislocation Multi-junctions and Strain Hardening

    Bulatov, V; Hsiung, L; Tang, M; Arsenlis, A; Bartelt, M; Cai, W; Florando, J; Hiratani, M; Rhee, M; Hommes, G; Pierce, T; Diaz de la Rubia, T


    At the microscopic scale, the strength of a crystal derives from the motion, multiplication and interaction of distinctive line defects--dislocations. First theorized in 1934 to explain low magnitudes of crystal strength observed experimentally, the existence of dislocations was confirmed only two decades later. Much of the research in dislocation physics has since focused on dislocation interactions and their role in strain hardening: a common phenomenon in which continued deformation increases a crystal's strength. The existing theory relates strain hardening to pair-wise dislocation reactions in which two intersecting dislocations form junctions tying dislocations together. Here we report that interactions among three dislocations result in the formation of unusual elements of dislocation network topology, termed hereafter multi-junctions. The existence of multi-junctions is first predicted by Dislocation Dynamics (DD) and atomistic simulations and then confirmed by the transmission electron microscopy (TEM) experiments in single crystal molybdenum. In large-scale Dislocation Dynamics simulations, multi-junctions present very strong, nearly indestructible, obstacles to dislocation motion and furnish new sources for dislocation multiplication thereby playing an essential role in the evolution of dislocation microstructure and strength of deforming crystals. Simulation analyses conclude that multi-junctions are responsible for the strong orientation dependence of strain hardening in BCC crystals.

  18. Folding and faulting of strain-hardening sedimentary rocks

    Johnson, A.M.


    The question of whether single- or multi-layers of sedimentary rocks will fault or fold when subjected to layer-parallel shortening is investigated by means of the theory of elastic-plastic, strain-hardening materials, which should closely describe the properties of sedimentary rocks at high levels in the Earth's crust. The most attractive feature of the theory is that folding and faulting, intimately related in nature, are different responses of the same idealized material to different conditions. When single-layers of sedimentary rock behave much as strain-hardening materials they are unlikely to fold, rather they tend to fault, because contrasts in elasticity and strength properties of sedimentary rocks are low. Amplifications of folds in such materials are negligible whether contacts between layer and media are bonded or free to slip for single layers of dolomite, limestone, sandstone, or siltstone in media of shale. Multilayers of these same rocks fault rather than fold if contacts are bonded, but they fold readily if contacts between layers are frictionless, or have low yield strengths, for example due to high pore-water pressure. Faults may accompany the folds, occurring where compression is increased in cores of folds. Where there is predominant reverse faulting in sedimentary sequences, there probably were few structural units. ?? 1980.

  19. Temperature Development during Hardening of Large Concrete Cubes

    Sørensen, Eigil V.; Burcharth, Hans Falk

    The purpose ofthe project is to verify ifthermal cracking will occur in large unreinforced concrete cubes due to large temperature differences during hardening o f the concrete. The first part o f the project is to numerically simulate the temperature development during hardening, evaluate the risk...... of thermally induced crackingunder varying execution conditions, and verify the temperature calculations by caJTying out measurements in situ. The cubes are cast and cured under marine environmental conditions in the north western part of Spain and are to serve as coastal proteetion in a harbour under...

  20. Temperature Development during Hardening of Large Concrete Cubes

    Sørensen, Eigil V.; Burcharth, Hans Falk

    The purpose ofthe project is to verify ifthermal cracking will occur in large unreinforced concrete cubes due to large temperature differences during hardening o f the concrete. The first part o f the project is to numerically simulate the temperature development during hardening, evaluate the risk...... of thermally induced cracking under varying execution conditions, and verify the temperature calculations by carrying out measurements in situ. The cubes are cast and cured under marine environmental conditions in the north western part of Spain and are to serve as coastal proteetion in a harbour under...

  1. Combined pulmonary fibrosis and emphysema: an increasingly recognized condition

    Olívia Meira Dias


    Full Text Available Combined pulmonary fibrosis and emphysema (CPFE has been increasingly recognized in the literature. Patients with CPFE are usually heavy smokers or former smokers with concomitant lower lobe fibrosis and upper lobe emphysema on chest HRCT scans. They commonly present with severe breathlessness and low DLCO, despite spirometry showing relatively preserved lung volumes. Moderate to severe pulmonary arterial hypertension is common in such patients, who are also at an increased risk of developing lung cancer. Unfortunately, there is currently no effective treatment for CPFE. In this review, we discuss the current knowledge of the pathogenesis, clinical characteristics, and prognostic factors of CPFE. Given that most of the published data on CPFE are based on retrospective analysis, more studies are needed in order to address the role of emphysema and its subtypes; the progression of fibrosis/emphysema and its correlation with inflammation; treatment options; and prognosis.

  2. Effects of Pre-Aging Condition on Multi-Step Aging Behavior in Al-Mg-Si Alloys

    Takaki, Yasuo; Masuda, Tetsuya; Kobayashi, Equo; Sato, Tatsuo

    The effects of pre-aging temperature on natural aging and following final aging (bake hardening) behavior in the Al-0.6mass%Mg-0.6mass%Si alloy were investigated by means of hardness test, tensile test, differential scanning calorimetry analysis (DSC) and transmission electron microscopy (TEM). As the results of hardness change, lower pre-aging temperature increase the natural age hardening, and decrease the bake harden-ability with natural aging time. By comparing DSC measurements and TEM observations, it is found that Cluster(1) formed during natural aging after the pre-aging, and the β" decomposition temperature is moved higher with natural aging time. The relationship of natural age hardening and bake hardening response suggested that the Cluster(1) suppressed the β" formation even if Cluster(2) coexistent condition.

  3. Onycholysis induced by nail hardener.

    Helsing, Per; Austad, Joar; Talberg, Hans Jørgen


    Nail hardeners appeared in the market during the 1960s. They were basically solutions of formaldehyde. The first adverse effects were published in 1966 (1). Reactions were onycholysis, chromonychia, subungual haemorrhage, and hyperkeratosis. Onycholysis may be non-inflammatory or inflammatory, and is accompanied by throbbing pain. Inflammatory reactions are followed by paronychia and occasional dermatitis on the digital pulpa.



    The mechanical properties and durability ( mainly frost-resistance and carbonation resistance ) of fly ash-CaO-CaSO4 .2H2O hardened paste are studied. The relationship among durability of harden ed fly ash paste, the quantity and distribution of hydrates and the initial p aste texture of hardened fly ash paste is presented.

  5. Determination and Analysis of Hardenability for Hot-Forging Die Steels with Deep-Hardening


    ERH end-quenching method was us ed to determine the hardenability of four kinds hot-forging die steels with dee p-hardening and hence the order of their hardenability was given. The tempering hardness of the steels was measured and the tempering resistance was studied. It was approved that ERH method is effective for the determination of hardenability of deep-hardening steel and the beginning of hardness drop in the ERH specimen is caused by bainite occurring.

  6. Reduction of work hardening rate in low-carbon steels

    Yalamanchili, Bhaskar Rao

    Low carbon grades of steel rods are used to produce finished products such as fine wire, coat hangers, staples, and roofing nails. These products are subject to ductility failures during production due to excessively high work hardening rates during wire drawing. The high work hardening rates are attributed to the presence of residuals, free nitrogen, or combinations thereof. This research concludes that the most cost-effective way to reduce the work hardening rate during wire drawing is to combine boron with nitrogen to form boron nitride, and thus reducing its work hardening contribution. The results of this study also conclude the following: (1) Boron/Nitrogen ratio is the more significant factor than rod tensile strength, which affects work hardening rate. Higher ratio is better in the 0.79 to 1.19 range. (2) Maintaining this narrow B/N range requires precise process control. (3) Process conditions such as dissolved oxygen (Steel Texas (North Star) benefited from this research by being able to provide a competitive edge in both quality and cost of its low carbon boron grades thus making North Star a preferred supplier of wire rod for these products.

  7. Cryptographic Path Hardening: Hiding Vulnerabilities in Software through Cryptography

    Ganesh, Vijay; Rinard, Martin


    We propose a novel approach to improving software security called Cryptographic Path Hardening, which is aimed at hiding security vulnerabilities in software from attackers through the use of provably secure and obfuscated cryptographic devices to harden paths in programs. By "harden" we mean that certain error-checking if-conditionals in a given program P are replaced by equivalent" we mean that adversaries cannot use semi-automatic program analysis techniques to reason about the hardened program paths and thus cannot discover as-yet-unknown errors along those paths, except perhaps through black-box dictionary attacks or random testing (which we can never prevent). Other than these unpreventable attack methods, we can make program analysis aimed at error-finding "provably hard" for a resource-bounded attacker, in the same sense that cryptographic schemes are hard to break. Unlike security-through-obscurity, in Cryptographic Path Hardening we use provably-secure crypto devices to hide errors and our mathemati...

  8. Ion-irradiation-induced hardening in Inconel 718

    Hunn, J. D.; Lee, E. H.; Byun, T. S.; Mansur, L. K.


    Inconel 718 is a material under consideration for areas in the target region of the spallation neutron source (SNS), now under construction at Oak Ridge National Laboratory (ORNL) in the US. In these positions, displacement damage from protons and neutrons will affect the mechanical properties. In addition, significant amounts of helium and hydrogen will build up in the material due to transmutation reactions. Nanoindentation measurements of solution-annealed (SA) Inconel 718 specimens, implanted with Fe-, He-, and H-ions to simulate SNS target radiation conditions, have shown that hardening occurs due to ion-induced displacement damage as well as due to the build-up of helium bubbles in the irradiated layer. Precipitation-hardened (PH) Inconel 718 also exhibited hardening by helium build-up but showed softening as a function of displacement damage due to dissolution of the γ ' and γ″ precipitates.


    Yusuf ŞAHİN


    Full Text Available The investigation of machining AISI 1050 carbon steels hardened to the 60 HRC hardness was carried out to determine the tool life and wear behaviour of the various cutting tools under different conditions. These experiments were conducted at using coated ceramic cutting tools and carbide cutting tools. The experimental results showed that the coated ceramic tools exhibited better performance than those of the coated carbide tools when machining the hardened steels. Moreover, wear behaviour of cutting tools were investigated in a scanning electron microscope. Electron microscopic examination also indicated that flank wear, thermal cracks on the tool nose combined with the nose deformation on the tools were responsible for the wear behaviour of the ceramic tools. For the carbide tools, however, removal of coated material from the substrate tool and combined with the crater wear were effective for the machining the hardened steel.

  10. Surface Fatigue Resistance with Induction Hardening

    Townsend, Dennis; Turza, Alan; Chapman, Mike


    Induction hardening has been used for some years to harden the surface and improve the strength and service life of gears and other components. Many applications that employ induction hardening require a relatively long time to finish the hardening process and controlling the hardness of the surface layer and its depth often was a problem. Other surface hardening methods, ie., carbonizing, take a very long time and tend to cause deformations of the toothing, whose elimination requires supplementary finishing work. In double-frequency induction hardening, one uses a low frequency for the preheating of the toothed wheel and a much higher frequency for the purpose of rapidly heating the surface by way of surface hardening.

  11. Energetic model of metal hardening

    Ignatova O.N.


    Full Text Available Based on Bailey hypothesis on the link between strain hardening and elastic lattice defect energy this paper suggests a shear strength energetic model that takes into consideration plastic strain intensity and rate as well as softening related to temperature annealing and dislocation annihilation. Metal strain hardening was demonstrated to be determined only by elastic strain energy related to the energy of accumulated defects. It is anticipated that accumulation of the elastic energy of defects is governed by plastic work. The suggested model has a reasonable agreement with the available experimental data for copper up to P = 70 GPa , for aluminum up to P = 10 GPa and for tantalum up to P = 20 GPa.

  12. Scintillation-Hardened GPS Receiver

    Stephens, Donald R.


    CommLargo, Inc., has developed a scintillation-hardened Global Positioning System (GPS) receiver that improves reliability for low-orbit missions and complies with NASA's Space Telecommunications Radio System (STRS) architecture standards. A software-defined radio (SDR) implementation allows a single hardware element to function as either a conventional radio or as a GPS receiver, providing backup and redundancy for platforms such as the International Space Station (ISS) and high-value remote sensing platforms. The innovation's flexible SDR implementation reduces cost, weight, and power requirements. Scintillation hardening improves mission reliability and variability. In Phase I, CommLargo refactored an open-source GPS software package with Kalman filter-based tracking loops to improve performance during scintillation and also demonstrated improved navigation during a geomagnetic storm. In Phase II, the company generated a new field-programmable gate array (FPGA)-based GPS waveform to demonstrate on NASA's Space Communication and Navigation (SCaN) test bed.

  13. Laser transformation hardening on rod-shaped carbon steel byGaussian beam

    Jong-Do KIM; Myeong-Hoon LEE; Su-Jin LEE; Woon-Ju KANG


    Laser transformation hardening(LTH) is one of the laser surface modification processes. The surface hardening of rod-shaped carbon steel (SM45C) was performed by lathe-based laser composite processor with Gaussian-beam optical head. The LTH characteristics by dominant processes, longitudinal and depth directional hardness distributions and behaviors of phase transformation in hardened zones were examined. Especially, two concepts of circumferential speed and theoretical overlap rate were applied. When laser power increased or circumferential speed decreased, the surface hardening depth gradually increases due to the increased heat input. Moreover, the longitudinal hardness distribution particularly shows periodicity of repetitive increase and decrease, which results from tempering effect by overlap. Finally, the feasibility of laser transformation hardening is verified by using the beam with Gaussian intensity distribution.

  14. The effects of x-ray beam hardening on detective quantum efficiency and radiation dose.

    Wong, Molly Donovan; Wu, Xizeng; Liu, Hong


    The goal of this preliminary study was to investigate the effects of x-ray beam hardening on the detective quantum efficiency (DQE) and the radiation dose of an inline x-ray imaging system. The ability to decrease the risk of harmful radiation to the patient without compromising the detection capability would more effectively balance the tradeoff between image quality and radiation dose, and therefore benefit the fields of diagnostic x-ray imaging, especially mammography. The DQE and the average glandular dose were both calculated under the same experimental conditions for a range of beam hardening levels, corresponding to no added beam hardening and two thicknesses each of Rhodium (Rh) and Molybdenum (Mo) filters. The dose calculation results demonstrate a reduction of 15% to 24% for the range of beam hardening levels. The comparison of all quantities comprising the DQE exhibit very close correlation between the results obtained without added beam hardening to the results corresponding to the range of beam hardening levels. For the specific experimental conditions utilized in this preliminary study, the results are an indication that the use of beam hardening holds the potential to reduce the radiation dose without decreasing the performance of the system. Future studies will seek to apply this method in a clinical environment and perform a comprehensive image quality evaluation, in an effort to further evaluate the potential of beam hardening to balance the tradeoff between dose and image quality.

  15. Influence of Hardening Model on Weld Residual Stress Distribution

    Mullins, Jonathan; Gunnars, Jens (Inspecta Technology AB, Stockholm (Sweden))


    This study is the third stage of a project sponsored by the Swedish Radiation Safety Authority (SSM) to improve the weld residual stress modelling procedures currently used in Sweden. The aim of this study was to determine which material hardening model gave the best agreement with experimentally measured weld residual stress distributions. Two girth weld geometries were considered: 19mm and 65mm thick girth welds with Rin/t ratios of 10.5 and 2.8, respectively. The FE solver ABAQUS Standard v6.5 was used for analysis. As a preliminary step some improvements were made to the welding simulation procedure used in part one of the project. First, monotonic stress strain curves and a mixed isotropic/kinematic hardening model were sourced from the literature for 316 stainless steel. Second, more detailed information was obtained regarding the geometry and welding sequence for the Case 1 weld (compared with phase 1 of this project). Following the preliminary step, welding simulations were conducted using isotropic, kinematic and mixed hardening models. The isotropic hardening model gave the best overall agreement with experimental measurements; it is therefore recommended for future use in welding simulations. The mixed hardening model gave good agreement for predictions of the hoop stress but tended to under estimate the magnitude of the axial stress. It must be noted that two different sources of data were used for the isotropic and mixed models in this study and this may have contributed to the discrepancy in predictions. When defining a mixed hardening model it is difficult to delineate the relative contributions of isotropic and kinematic hardening and for the model used it may be that a greater isotropic hardening component should have been specified. The kinematic hardening model consistently underestimated the magnitude of both the axial and hoop stress and is not recommended for use. Two sensitivity studies were also conducted. In the first the effect of using a

  16. [Optimal coefficient of overlap of light spots during laser hardening of medical instruments].

    Stepanova, G A; Pogibenko, A V; Gerasev, G P


    The optimum coefficient of light spot intercepts in the course of laser hardening medical instruments is determined for the case when there are no unirradiated sites on the surface under treatment. The increase in the light spot diameter during irradiation has been shown to be followed by more rapid expansion of the hardened area in comparison with the one of the tempered zone.


    Wei-Dan Ding,


    Full Text Available This study examines the dimensional stability of fast-growing poplar clones wood after treatment by impregnation with methyl methacrylate (MMA. Six hybrid poplar clones from one plantation in Quebec were sampled. The effects of hardening with MMA on density as well as longitudinal, radial, tangential, and volumetric swelling properties (S, water uptake capacity (D, anti-swelling efficiency (ASE, and water repellent efficiency (WRE after soaking were investigated. Hardening treatment increased the density of all poplar woods by 1.2 to 1.6 and decreased the inner water migration rate during soaking. S and D values of hardened woods were significantly lower than those of controls, depending on the clone type. ASE and WRE values suggested that incorporating MMA effectively improved the dimensional stability of poplar wood at the early soaking stage, but was less effective in the long term.

  18. Diffusive Origin of the Cosmic-Ray Spectral Hardening

    Tomassetti, N


    Recent data from ATIC, CREAM and PAMELA revealed that the energy spectra of cosmic ray (CR) nuclei above 100 GeV/nucleon experience a remarkable hardening with increasing energy. This effect cannot be recovered by the conventional descriptions of CR acceleration and diffusive propagation processes. Using analytical calculations, I show that the hardening effect can be consequence of a spatial change of the CR diffusion properties in different regions of the Galaxy. I discuss the implications of this scenario for the main CR observables and its connections with the open issues of the CR physics.


    D.G. Lee; K.C.Jang; J.M. Kuk; I.S. Kim


    Rotary bending fatigue tests were carried out with two kinds of materials, S43C and S50C, using the front engine and front drive shaft (FF shaft) of vehicle. The specimens were induction hardened about 1.0mm depth from the specimen surface, and the hardness value on the surface was about HRC56-60. The tested environment temperatures were -30, 25 and 80℃ in order to look over effect of the induction hardening and the environmental temperatures on the fatigue characteristics. The fatigue limit of induction hardened specimens increased more about 45%than non-hardened specimens showing that the endurances of S43C and S50C were 98.1 and 107.9MPa in non-hardened samples, 147.1 and 156.9MPa in hardened samplesrespectably. The maximum tensile and compressive stress on the small circular defect was about +250 and -450MPa respectively when circular defect is situated on top and bottom. The fatigue life increased 80, 25and -30℃ in order regardless of hardening. In comparison of the fatigue lives on the basis of tested result at 25℃, the fatigue lives of non-hardened specimens decreased about 35%, but that of hardened specimens decreased about only 5% at 80℃ more than at 25℃. And fatigue life of non-hardened and hardened specimens were about 110% and 120% higher at -30℃ than that of 25℃. Based on the result of stress distribution near the defect, the tensile and compressive stress repeatedly generated by load direction were the largest on the small circular defect due to the stress concentration.

  20. Changes in morpho-physiological attributes of Eucalyptus globulus plants in response to different drought hardening treatments

    Coopman, Rafael E.; Jara,Jorge C; Bravo,Leon A; Sáez,Katia L; Mella,Gloria R; Escobar,Rene


    Morpho-physiological attributes exhibited in response to drought hardening at the end of the growing season of Eucalyptus globulus Labill under nursery conditions were studied to evaluate the effect of three drought hardening treatments in morpho-physiological traits used as suitable indicators of drought hardiness, such as, plant growth, root growth potential, plant water relationships and survival. Freezing resistance of drought hardened plants was also studied in order to evaluate cross ha...

  1. Radiation Hardened Electronics for Extreme Environments

    Keys, Andrew S.; Watson, Michael D.


    The Radiation Hardened Electronics for Space Environments (RHESE) project consists of a series of tasks designed to develop and mature a broad spectrum of radiation hardened and low temperature electronics technologies. Three approaches are being taken to address radiation hardening: improved material hardness, design techniques to improve radiation tolerance, and software methods to improve radiation tolerance. Within these approaches various technology products are being addressed including Field Programmable Gate Arrays (FPGA), Field Programmable Analog Arrays (FPAA), MEMS Serial Processors, Reconfigurable Processors, and Parallel Processors. In addition to radiation hardening, low temperature extremes are addressed with a focus on material and design approaches.

  2. Dilatant hardening of fluid-saturated sandstone

    Makhnenko, Roman Y.; Labuz, Joseph F.


    The presence of pore fluid in rock affects both the elastic and inelastic deformation processes, yet laboratory testing is typically performed on dry material even though in situ the rock is often saturated. Techniques were developed for testing fluid-saturated porous rock under the limiting conditions of drained, undrained, and unjacketed response. Confined compression experiments, both conventional triaxial and plane strain, were performed on water-saturated Berea sandstone to investigate poroelastic and inelastic behavior. Measured drained response was used to calibrate an elasto-plastic constitutive model that predicts undrained inelastic deformation. The experimental data show good agreement with the model: dilatant hardening in undrained triaxial and plane strain compression tests under constant mean stress was predicted and observed.

  3. Simultaneous surface engineering and bulk hardening of precipitation hardening stainless steel

    Frandsen, Rasmus Berg; Christiansen, Thomas; Somers, Marcel A. J.


    This article addresses simultaneous bulk precipitation hardening and low temperature surface engineering of two commercial precipitation hardening stainless steels: Sandvik Nanoflex® and Uddeholm Corrax®. Surface engineering comprised gaseous nitriding or gaseous carburising. Microstructural....... The duration and temperature of the nitriding/carburising surface hardening treatment can be chosen in agreement with the thermal treatment for obtaining optimal bulk hardness in the precipitation hardening stainless steel....

  4. Numerical analysis of drilling hole work-hardening effects in hole-drilling residual stress measurement

    Li, H.; Liu, Y. H.


    The hole-drilling strain gage method is an effective semi-destructive technique for determining residual stresses in the component. As a mechanical technique, a work-hardening layer will be formed on the surface of the hole after drilling, and affect the strain relaxation. By increasing Young's modulus of the material near the hole, the work-hardening layer is simplified as a heterogeneous annulus. As an example, two finite rectangular plates submitted to different initial stresses are treated, and the relieved strains are measured by finite element simulation. The accuracy of the measurement is estimated by comparing the simulated residual stresses with the given initial ones. The results are shown for various hardness of work-hardening layer. The influence of the relative position of the gages compared with the thickness of the work-hardening layer, and the effect of the ratio of hole diameter to work-hardening layer thickness are analyzed as well.


    V. I. Serebrovskii


    Full Text Available Summary. Currently in the repair and manufacture at the stage of recovery of steel parts, widely used special coatings formed by electrolytic effects on ferrous ions. This technique offers high performance, ease of implementation, low cost of technological equipment and materials used, as well as easy automation of the process. However, this method has several disadvantages: low fatigue strength of reconditioned parts, insufficiently strong grip of the iron coating to the substrate, particularly in alloy steels, insufficient wear resistance. For the purpose of increasing durability and wear resistance of parts, restored through electrochemical action, it is proposed to use chemical-heat treatment, consisting in the application of carbonitriding. Investigated the efficacy of different modes of carbonitriding in the highly carburizing paste-and their influence on the structure and properties of iron plating. It is established that the nitrocarburizing both low and high temperatures repeatedly (6-7.5 times increases the microhardness of the coatings. The highest hardness is obtained by low-temperature carbonitriding with direct quenching in water. Conducting the carbonitriding process at low temperatures (650 °C, significantly increases the hardness of the iron coatings, increasing the limit of its fluidity, a and also greatly increases its endurance limit. Nitrocarburized fatigue strength of samples with iron precipitation on the surface, as shown by our studies, not only higher strength of the same samples without carbonitriding (more than 2 times, but higher than the fatigue strength of the base metal without coatings. Raising the temperature of the carbonitriding did not increase the hardness of electrolytic iron. Developed a rational technology of hardening of steel parts, re-chain iron fortification. Selected optimum conditions for carbonitriding hardening restored iron fortification, with the purpose of increasing durability of machine

  6. Challenges in hardening technologies using shallow-trench isolation

    Shaneyfelt, M.R.; Dodd, P.E.; Draper, B.L.; Flores, R.S.


    Challenges related to radiation hardening CMOS technologies with shallow-trench isolation are explored. Results show that trench hardening can be more difficult than simply replacing the trench isolation oxide with a hardened field oxide.

  7. Investigation of a Hardened Cement Paste Grout

    Esteves, Luis Pedro; Sørensen, Eigil Verner

    This report documents a series of tests performed on a hardened cement paste grout delivered by the client, Det Norske Veritas A/S.......This report documents a series of tests performed on a hardened cement paste grout delivered by the client, Det Norske Veritas A/S....

  8. Method of hardening a fluid mass

    Zitha, P.L.J.; Jansen, J.D.


    The invention relates to a method of hardening a fluid mass in contact with a wall, in a desirable shape. According to the invention, the fluid mass is a magneto-rheological fluid mixture that in addition to at least one hardening component comprises a particulate magnetic component, with minimally

  9. Method of hardening a fluid mass

    Zitha, P.L.J.; Jansen, J.D.


    The invention relates to a method of hardening a fluid mass in contact with a wall, in a desirable shape. According to the invention, the fluid mass is a magneto-rheological fluid mixture that in addition to at least one hardening component comprises a particulate magnetic component, with minimally

  10. Keystroke Dynamics-Based Credential Hardening Systems

    Bartlow, Nick; Cukic, Bojan

    abstract Keystroke dynamics are becoming a well-known method for strengthening username- and password-based credential sets. The familiarity and ease of use of these traditional authentication schemes combined with the increased trustworthiness associated with biometrics makes them prime candidates for application in many web-based scenarios. Our keystroke dynamics system uses Breiman’s random forests algorithm to classify keystroke input sequences as genuine or imposter. The system is capable of operating at various points on a traditional ROC curve depending on application-specific security needs. As a username/password authentication scheme, our approach decreases the system penetration rate associated with compromised passwords up to 99.15%. Beyond presenting results demonstrating the credential hardening effect of our scheme, we look into the notion that a user’s familiarity to components of a credential set can non-trivially impact error rates.

  11. Comparison of Thermal Creep Strain Calculation Results Using Time Hardening and Strain Hardening Rules

    Kim, Junehyung; Cheon, Jinsik; Lee, Byoungoon; Lee, Chanbock [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)


    One of the design criteria for the fuel rod in PGSFR is the thermal creep strain of the cladding, because the cladding is exposed to a high temperature for a long time during reactor operation period. In general, there are two kind of calculation scheme for thermal creep strain: time hardening and strain hardening rules. In this work, thermal creep strain calculation results for HT9 cladding by using time hardening and strain hardening rules are compared by employing KAERI's current metallic fuel performance analysis code, MACSIS. Also, thermal creep strain calculation results by using ANL's metallic fuel performance analysis code, LIFE-METAL which adopts strain hardening rule are compared with those by using MACSIS. Thermal creep strain calculation results for HT9 cladding by using time hardening and strain hardening rules were compared by employing KAERI's current metallic fuel performance analysis code, MACSIS. Also, thermal creep strain calculation results by using ANL's metallic fuel performance analysis code, LIFE-METAL which adopts strain hardening rule were compared with those by using MACSIS. Tertiary creep started earlier in time hardening rule than in strain hardening rule. Also, calculation results by MACSIS with strain hardening and those obtained by using LIFE-METAL were almost identical to each other.

  12. Local hardening evaluation of carbon steels by using frequency sweeping excitation and spectrogram method

    Tsuchida, Yuji; Kudo, Yuki; Enokizono, Masato


    This paper presents our proposed frequency sweeping excitation and spectrogram method (FSES method) by a magnetic sensor for non-destructive testing of hardened low carbon steels. This method can evaluate the magnetic properties of low carbon steels which were changed after induction heating treatment. It was examined by our proposed method that the degrees of yield strength of low carbon steels were varied depending on hardened conditions. Moreover, it was made clear that the maximum magnetic field strength, Hmax, derived from the measured B-H loops was very sensitive to the hardening if the surface of the samples were flat.

  13. Strain hardening of polymer glasses: Entanglements, energetics, and plasticity

    Hoy, Robert S.; Robbins, Mark O.


    Simulations are used to examine the microscopic origins of strain hardening in polymer glasses. While stress-strain curves for a wide range of temperature can be fit to the functional form predicted by entropic network models, many other results are fundamentally inconsistent with the physical picture underlying these models. Stresses are too large to be entropic and have the wrong trend with temperature. The most dramatic hardening at large strains reflects increases in energy as chains are pulled taut between entanglements rather than a change in entropy. A weak entropic stress is only observed in shape recovery of deformed samples when heated above the glass transition. While short chains do not form an entangled network, they exhibit partial shape recovery, orientation, and strain hardening. Stresses for all chain lengths collapse when plotted against a microscopic measure of chain stretching rather than the macroscopic stretch. The thermal contribution to the stress is directly proportional to the rate of plasticity as measured by breaking and reforming of interchain bonds. These observations suggest that the correct microscopic theory of strain hardening should be based on glassy state physics rather than rubber elasticity.


    V. A. Tomilo


    Full Text Available Various schemes of ultrasonic oscillatory system are developed: with a «force nonsensitive» support, with a «force sensitive» support, with the deforming steel balls in bulk. Results of the ultrasonic treatment showed that hardening of a surface of the samples took place when the vibration amplitude of a radiator exceeds a certain level. The level of hardening increases with increase in amplitude of fluctuations of a radiator. Higher level of hardening is registered when the surface is treated by steel balls.

  15. Work Hardening Behavior of 1020 Steel During Cold-Beating Simulation

    CUI, Fengkui; LING, Yuanfei; XUE, Jinxue; LIU, Jia; LIU, Yuhui; LI, Yan


    The present research of cold-beating formation mainly focused on roller design and manufacture, kinematics, constitutive relation, metal flow law, thermo-mechanical coupling, surface micro-topography and microstructure evolution. However, the research on surface quality and performance of workpieces in the process of cold-beating is rare. Cold-beating simulation experiment of 1020 steel is conducted at room temperature and strain rates ranging from 2000 to 4000 s-1 base on the law of plastic forming. According to the experimental data, the model of strain hardening of 1020 steel is established, Scanning Electron Microscopy(SEM) is conducted, the mechanism of the work hardening of 1020 steel is clarified by analyzing microstructure variation of 1020 steel. It is found that the strain rate hardening effect of 1020 steel is stronger than the softening effect induced by increasing temperatures, the process of simulation cold-beating cause the grain shape of 1020 steel significant change and microstructure elongate significantly to form a fibrous tissue parallel to the direction of deformation, the higher strain rate, the more obvious grain refinement and the more hardening effect. Additionally, the change law of the work hardening rate is investigated, the relationship between dislocation density and strain, the relationship between work hardening rate and dislocation density is obtained. Results show that the change trend of the work hardening rate of 1020 steel is divided into two stages, the work hardening rate decreases dramatically in the first stage and slowly decreases in the second stage, finally tending toward zero. Dislocation density increases with increasing strain and strain rate, work hardening rate decreases with increasing dislocation density. The research results provide the basis for solving the problem of improving the surface quality and performance of workpieces under cold-beating formation of 1020 steel.

  16. Direct observation of Lomer-Cottrell locks during strain hardening in nanocrystalline nickel by in situ TEM.

    Lee, Joon Hwan; Holland, Troy B; Mukherjee, Amiya K; Zhang, Xinghang; Wang, Haiyan


    Strain hardening capability is critical for metallic materials to achieve high ductility during plastic deformation. A majority of nanocrystalline metals, however, have inherently low work hardening capability with few exceptions. Interpretations on work hardening mechanisms in nanocrystalline metals are still controversial due to the lack of in situ experimental evidence. Here we report, by using an in situ transmission electron microscope nanoindentation tool, the direct observation of dynamic work hardening event in nanocrystalline nickel. During strain hardening stage, abundant Lomer-Cottrell (L-C) locks formed both within nanograins and against twin boundaries. Two major mechanisms were identified during interactions between L-C locks and twin boundaries. Quantitative nanoindentation experiments recorded show an increase of yield strength from 1.64 to 2.29 GPa during multiple loading-unloading cycles. This study provides both the evidence to explain the roots of work hardening at small length scales and the insight for future design of ductile nanocrystalline metals.

  17. Optimizing hardenability of high chromium white cast iron

    SU Ying-long; LI Dan; ZHANG Xue-kun


    The formulas proposed by J. Dodd and J. L. Parks for calculating the hardenability of high-Cr white cast iron under continuous cooling condition was recommended. For broader application, some supplements were made to the formula. Through tests on the half-cooling time of typical castings, the compositions of ideal alloys were precisely designed using the Dodd's formula. Hardness testing of heat-treated castings showed that the designed compositions were correct. The application of castings demonstrated excellent abrasion resistance.

  18. The influence of Glassex additive on properties of microwave-hardened and self- hardened moulding sands with water glass

    K. Major-Gabryś


    Full Text Available The article takes into consideration the researches concerning inserting the Glassex additive to the microwaved-hardened and self- hardened moulding sands with water glass. In the research different types of ester hardeners to self-hardened moulding sands with water glass were used. The influence of Glassex additive on retained strength of moulding sands with different hardeners and prepared by different technologies of hardening were tested. The influence of different hardeners and the technology of hardening on retained strength of moulding sand with water glass and the Glassex additive were also estimated.

  19. Observation of a New Mechanism Balancing Hardening and Softening in Metals

    Yu, Tianbo; Hansen, Niels; Huang, Xiaoxu


    Plastic deformation of metals refines the microstructure and increases the strength through work hardening, but this effect of deformation is counterbalanced by dynamic recovery. After large strain, the microstructure typically shows a lamellar morphology, with finely spaced lamellar boundaries c...

  20. Synthesis of a new hardener agent for self-healing epoxy resins

    Raimondo, Marialuigia; Guadagno, Liberata; Naddeo, Carlo; Longo, Pasquale; Mariconda, Annaluisa; Agovino, Anna


    Actually, the development of smart composites capable of self-repair in aeronautical structures is still at the planning stage owing to complex issues to overcome. One of the critical points in the development of self-healing epoxy resin is related to the impossibility to employ primary amines as hardeners. In this paper, the synthesis of a new hardener for self-healing resins is shown together with applicability conditions/ranges.

  1. Elastic constant versus temperature behavior of three hardened maraging steels

    Ledbetter, H. M.; Austin, M. W.


    Elastic constants of three maraging steels were determined by measuring ultrasonic velocities. Annealed steels show slightly lower bulk moduli and considerably lower shear moduli than hardened steels. All the elastic constants (Young's modulus, shear modulus, bulk modulus and Poisson's ratio) show regular temperature behavior between 76 and 400 K. Young's modulus and the shear modulus increase with increasing yield strength, but the bulk modulus and Poisson's ratio are relatively unchanged. Elastic anisotropy is quite small.

  2. Increased resistance to free radical damage induced by low-level sound conditioning.

    Harris, Kelly Carney; Bielefeld, Eric; Hu, Bo Hua; Henderson, Donald


    Conditioning is the phenomenon where exposure to moderate-level acoustic stimuli can increase the ear's resistance to subsequent more intense sound exposures. In recent years, research has shown that conditioning increases the availability of antioxidant enzymes which presumably protects the ear from oxidative stress induced by a traumatic noise exposure [Jacono, A.A., Hu, B., Kopke, R.D., Henderson, D., Van De Water, T.R., Steinman, H.M., 1998. Changes in cochlear antioxidant enzyme activity after sound conditioning and noise exposure in the chinchilla. Hear Res 117, 31-8]. The current study was designed to assess whether the increase in endogenous antioxidants seen following conditioning could provide protection from oxidative stress induced by Paraquat, a potent generator of superoxide. Chinchillas were exposed to a conditioning noise, 500 Hz OBN at 95 dB for 6 h/day for 10 days, followed 5 days later with Paraquat application to the round window. Controls underwent the Paraquat application surgery, without prior conditioning. Evoked potential thresholds were determined prior to conditioning, at day 1, 5 and 10 during conditioning, at day 15 (5 days after conditioning), and at day 17, 19, 23, and 35 (1, 3, 7, and 20 days post-Paraquat). The conditioned animals showed reductions in permanent threshold shift and reduced inner hair cell loss relative to controls. These results reinforce the hypothesis that antioxidants are primary mediators of the conditioning effect.

  3. Hardening of the surface layers of a hollow billet formed by centrifugal casting

    Chumanov, V. I.; Chumanov, I. V.; Anikeev, A. N.; Garifulin, R. R.


    One of the methods to increase the mechanical properties of steel is its hardening via the introduction of a refractory fine-grained phase into a melt. A method of fabrication of a tube blank by centrifugal casting accompanied by hardening with a refractory phase is considered. The introduction of fine tungsten and silicon carbides is shown to improve the structure of grade 15 steel and to increase the wear resistance of a tube blank made of this steel.

  4. Aerobic conditions increase isoprenoid biosynthesis pathway gene expression levels for carotenoid production in Enterococcus gilvus.

    Hagi, Tatsuro; Kobayashi, Miho; Nomura, Masaru


    Some lactic acid bacteria that harbour carotenoid biosynthesis genes (crtNM) can produce carotenoids. Although aerobic conditions can increase carotenoid production and crtNM expression levels, their effects on the pathways that synthesize carotenoid precursors such as mevalonate and isoprene are not completely understood. In this study, we investigated whether aerobic conditions affected gene expression levels involved in the isoprenoid biosynthesis pathway that includes the mevalonate and isoprene biosynthesis pathways in Enterococcus gilvus using real-time quantitative reverse transcription PCR. NADH oxidase (nox) and superoxide dismutase (sod) gene expression levels were investigated as controls for aerobic conditions. The expression levels of nox and sod under aerobic conditions were 7.2- and 8.0-fold higher, respectively, than those under anaerobic conditions. Aerobic conditions concomitantly increased the expression levels of crtNM carotenoid biosynthesis genes. HMG-CoA synthase gene expression levels in the mevalonate pathway were only slightly increased under aerobic conditions, whereas the expression levels of HMG-CoA reductase and five other genes in the isoprene biosynthesis pathways were 1.2-2.3-fold higher than those under anaerobic conditions. These results demonstrated that aerobic conditions could increase the expression levels of genes involved in the isoprenoid biosynthesis pathway via mevalonate in E. gilvus.

  5. Process for hardening the surface of polymers

    Mansur, Louis K.; Lee, Eal H.


    Hard surfaced polymers and the method for making them is generally described. Polymers are subjected to simultaneous multiple ion beam bombardment, that results in a hardening of the surface and improved wear resistance.

  6. Equivalent Plastic Strain Gradient Plasticity with Grain Boundary Hardening and Comparison to Discrete Dislocation Dynamics

    Bayerschen, E; Wulfinghoff, S; Weygand, D; Böhlke, T


    The gradient crystal plasticity framework of Wulfinghoff et al. [53] incorporating an equivalent plastic strain and grain boundary yielding, is extended with additional grain boundary hardening. By comparison to averaged results from many discrete dislocation dynamics (DDD) simulations of an aluminum type tricrystal under tensile loading, the new hardening parameter in the continuum model is calibrated. It is shown that although the grain boundaries (GBs) in the discrete simulations are impenetrable, an infinite GB yield strength corresponding to microhard GB conditions, is not applicable in the continuum model. A combination of a finite GB yield strength with an isotropic bulk Voce hardening relation alone also fails to model the plastic strain profiles obtained by DDD. Instead, a finite GB yield strength in combination with GB hardening depending on the equivalent plastic strain at the GBs is shown to give a better agreement to DDD results. The differences in the plastic strain profiles obtained in DDD simu...

  7. Numerical predicting of the structure and stresses state in hardened element made of tool steel

    A. Bokota


    Full Text Available The paper presents numerical model of thcrmal phcnomcna, phasc transformation and mcchanical phcnomcna associated with hardeningof carbon tool steel. Model for evaluation or fractions OF phases and their kinetics bascd on continuous heating diagram (CHT andcontinuous cooling diagram (CCT. The stresses generated during hardening were assumed to rcsult from ~hermal load. stntcturaI plasticdeformations and transformation plasricity. Thc hardened material was assumed to be elastic-plastic, and in ordcr to mark plastic strains the non-isothermal plastic law of flow with the isotropic hardening and condition plasticity of Huber-Misses were used. TherrnophysicaI values of mechanical phenomena dependent on bo~hth e phase composition and temperature. In the numerical example thc simulated estimation of the phasc Fraction and strcss distributions in the hardened axisimmetrical elemcnt was performed.

  8. CO2硬化水玻璃旧砂的湿法再生探索%Conditions of Wet Reclamation for Used Sodium Silicate Sand Hardened by CO2

    陈锐; 卢鑫; 谭捷; 谭远友


    现代铸造业发展的一个重要目标是绿色铸造。水玻璃砂是最有可能实现绿色制造的型砂,水玻璃旧砂的再生回用是其关键。本文探讨了不同转速、时间、温度条件下湿法再生 CO2硬化水玻璃旧砂的效果。结果表明:适宜的参数为转速800 r/min,时间10 min,温度80℃,用水量1砄1,再生砂残留碱约为3%。%Green casting was an important goal in the development of modern foundry industry.Sodium silicate sand ( SSS) was most likely molding sand achieve green manufacturing of green sand , and SSS regeneration recycling was the key of the green manufacturing.SSS regeneration CO 2 hardening affecting in different speed , time and temperature was discussed.The results showed that optimum reactions according to the volume of acid consumed were rotate speed of 800 r/min, water consumption of 500 mL: 500 g sodium silicate sand , reaction temperature of 80 ℃ and reaction time was 10 min.Residual alkali reclaimed in the sand was about 3%.

  9. Free Vibration and Hardening Behavior of Truss Core Sandwich Beam

    J. E. Chen


    Full Text Available The dynamic characteristics of simply supported pyramidal truss core sandwich beam are investigated. The nonlinear governing equation of motion for the beam is obtained by using a Zig-Zag theory. The averaged equations of the beam with primary, subharmonic, and superharmonic resonances are derived by using the method of multiple scales and then the corresponding frequency response equations are obtained. The influences of strut radius and core height on the linear natural frequencies and hardening behaviors of the beam are studied. It is illustrated that the first-order natural frequency decreases continuously and the second-order and third-order natural frequencies initially increase and then decrease with the increase of strut radius, and the first three natural frequencies all increase with the rise of the core height. Furthermore, the results indicate that the hardening behaviors of the beam become weaker with the increase of the rise of strut radius and core height. The mechanisms of variations in hardening behavior of the sandwich beam with the three types of resonances are detailed and discussed.


    A. V. Kovalchuk


    Full Text Available The method of complex surface hardening of steel detailswas designed. The method is a compound of two processes of hardening: chemical heat treatment and physical vapor deposition (PVD of the coating. The result, achieved in this study is much higher, than in other work on this topic and is cumulative. The method designed can be used in mechanical engineering, medicine, energetics and is perspective for military and space technologies.

  11. Properties and Commercial Application of Manual Plasma Hardening

    Korotkov, V. A.


    A new method and a device for plasma hardening of various parts are considered. Installation of the new device does not require too much investment (the active mechanical productions are appropriate for its accommodation) and special choice of personnel (welders train to use it without difficulty). Plasma hardening does not deform and worsen the smoothness of the surface, which makes it possible to employ many hardened parts without finishing mechanical treatment required after bulk or induction hardening. The hardened layer (about 1 mm) produced by plasma hardening exhibits better wear resistance than after bulk hardening with tempering, which prolongs the service life of the parts.

  12. Infrared Camera Analysis of Laser Hardening

    J. Tesar


    Full Text Available The improvement of surface properties such as laser hardening becomes very important in present manufacturing. Resulting laser hardening depth and surface hardness can be affected by changes in optical properties of material surface, that is, by absorptivity that gives the ratio between absorbed energy and incident laser energy. The surface changes on tested sample of steel block were made by engraving laser with different scanning velocity and repetition frequency. During the laser hardening the process was observed by infrared (IR camera system that measures infrared radiation from the heated sample and depicts it in a form of temperature field. The images from the IR camera of the sample are shown, and maximal temperatures of all engraved areas are evaluated and compared. The surface hardness was measured, and the hardening depth was estimated from the measured hardness profile in the sample cross-section. The correlation between reached temperature, surface hardness, and hardening depth is shown. The highest and the lowest temperatures correspond to the lowest/highest hardness and the highest/lowest hardening depth.

  13. Impact of air conditioning system operation on increasing gases emissions from automobile

    Burciu, S. M.; Coman, G.


    The paper presents a study concerning the influence of air conditioning system operation on the increase of gases emissions from cars. The study focuses on urban operating regimes of the automobile, regimes when the engines have low loads or are operating at idling. Are presented graphically the variations of pollution emissions (CO, CO2, HC) depending of engine speed and the load on air conditioning system. Additionally are presented, injection duration, throttle position, the mechanical power required by the compressor of air conditioning system and the refrigerant pressure variation on the discharge path, according to the stage of charging of the air conditioning system.

  14. Study on microstructures and work hardening behavior of ferrite-martensite dual-phase steels with high-content martensite

    Xiurong Zuo


    Full Text Available A kind of medium-carbon low-alloy dual-phase steels with high-content martensite produced by intercritical annealing at 785-830 ºC for 10-50 minutes were studied in aspect of microstructures and work hardening behavior using SEM and tensile testing machine. The experimental results showed that the work hardening of the studied steels obeyed the two-stage work hardening mechanism, whose work hardening exponent of the first stage was higher than that of the second stage. The work hardening exponent increased with increasing the intercritical annealing temperature and time. For series A steel intercritically annealed at 785 ºC with starting microstructure of ferrite plus pearlite, austenite nucleated at the pearlite colonies, so the holding time of only 50 minutes can increase the work hardening exponent obviously. For series B steel with starting microstructure of martensite, austenite nucleated at lath interfaces, lath colony boundaries of primary martensite and carbides, accelerating the formation of austenite, so holding time for 30 minutes made the work hardening exponent increase obviously. High work hardening rate during initial plastic deformation (<0.5% strain was observed.

  15. [Electrophysiological mechanisms and possibility of increasing figural creativity under conditions of monetary reward].

    Vol'f, N V; Tarasova, I V


    Analysis of EEG correlates of figural creativity (Torrens "Incomplete figures" subtest) and its efficacy after the instruction "to create an original solution" (condition I) and after the same instruction with the promise of a monetary reward for high performance (condition II) was carried out. Fifteen right-handed men and 16 women were examined. In condition II, the image originality was not increased, but performance fluency was reduced as compared to condition I. Promise of the monetary reward in condition II was followed by a decrease in the theta1-rhythm power before the task performance, which persisted during the image creation. Baseline values of the power of rhythms alpha1 and 2 were higher in condition II as compared to condition 1. Promise of the monetary reward in condition II was associated with a reduction of the experimental beta1- and beta2-rhythm power in posterior regions of the cerebral cortex. These effects may be associated with pre-setting to the forthcoming activity and task performance under increased extrinsic motivation. The enhancement of external motivation in condition II also induced changes in hemispheric power asymmetry of the teta1-, alpha1, and beta2-rhythm at the expense of the left-hemisphere activity, which may be the basis of different effects of high motivation levels on subjects, who preferred right or left hemispheric strategies during figural divergent thinking.

  16. Stage IV work-hardening related to disorientations in dislocation structures

    Pantleon, W.


    . Disorientations evolving from purely statistical reasons — leading to a square root dependence of the average disorientation angle on strain — affect the initial work-hardening rate (and the saturation stress) of stage III only slightly. On the other hand, deterministic contributions to the development...... of disorientations, as differences in the activated slip systems across boundaries, cause a linear increase of the flow stress at large strains. Such a constant work-hardening rate is characteristic for stage IV....

  17. Design Features of Hardening Turners with Outstripping Plastic Deformation

    V. M. Yaroslavtsev


    Full Text Available An efficiency of the cutting method with outstripping plastic deformation (OPD in lathe works is defined in many respects by design features of the add-on devices for mechanical hardening of a cut-off layer material in the course of cutting. Applied on lathes, deforming OPD devices can have differing dimensions, placement on the lathe, drive type (manual, electric, hydraulic, pneumatic, pneumohydraulic, electromagnetic, and autonomy degree towards the metalcutting equipment and industrial equipment.At the same time there are a number of inherent design features of work-hardening devices the modernized lathes with OPD use for machining. Now the OPD standard devices implement two principle construction options: loading device is placed on the machine or on the OPD slide support separate of the tool, or it is structurally aligned with the cutting tool. In the latter case the OPD device for turning is called a tool mandrel, which is mounted in a tool post of the machine or, at large dimensions, such a mandrel is mounted on the machine instead of the tool mandrel.When designing the OPD devices, is important to take into consideration production requirements and recommendations for the technological equipment, developed in the course of creation, working off and introduction of such installations for mechanical hardening of material. In compliance with it, OPD devices, their placement on the machine, and working displacements shouldn't limit technological capabilities of the applied metal-cutting equipment. OPD stresses have to be smoothly regulated, with maximum loads being limited to admissible values for the machine model to be modernized. It is necessary to ensure synchronized longitudinal and cross displacements of the cutting tool and OPD hardener with respect to the axis of billet rotation to enable regulation and readjustment of the hardener and tool placement. It ought to foresee the increased mobile components rigidity and manufacturing

  18. Age-hardening in a commercial Mg-based alloy

    Macchi, C.E. [IFIMAT, UNCentro and CONICET, Pinto 399, B7000GHG Tandil (Argentina); Somoza, A. [IFIMAT, UNCentro and CICPBA, Pinto 399, B7000GHG Tandil (Argentina); Nie, J.F. [School of Physics and Materials Engineering, PO Box 69M, Monash University, Victoria 3800 (Australia)


    Age-hardening phenomena induced by thermal and thermo-mechanical treatments in the commercial Mg-based alloy WE54 were studied by positron annihilation lifetime spectroscopy and Vickers microhardness. To this aim, samples were plastically deformed and subsequently aged at 250 C for times ranging from 0 to 1000 hours. The results obtained are discussed in terms of the role of vacancies in the solute transport and therefore they contribute to the discussion on the vacancy-solute clusters (and/or intermediate precipitates) interactions during the precipitation sequence of the WE54. Besides, we show that cold work previous aging not only accelerates but increases the hardening response of the alloy. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Use of rapidly hardening hydroxyapatite cement for facial contouring surgery.

    Lee, Dong Won; Kim, Ji Ye; Lew, Dae Hyun


    Hydroxyapatite cement is an ideal alloplastic material to replace the autogenous bone grafts in craniofacial surgery. Hydroxyapatite cement is advantageous because it can be easily molded by hand unlike other alloplastic materials such as silicone and high-density polyethylene. For aesthetic applications of hydroxyapatite cement, we evaluated the efficacy and safety of the rapidly hardening hydroxyapatite cement used in facial contour augmentation, especially for the forehead and the malar area. A total of 18 cases of facial skeleton augmentation or contouring surgery using rapidly hardening hydroxyapatite cement (Mimix; Biomet, Warsaw, IN) were examined, and the long-term cosmetic results and any complications were also analyzed. The aims of facial contouring surgeries were to correct the following conditions: hemifacial microsomia, craniosynostosis, posttraumatic facial deformity, deformity after tumor resection, dentofacial deformity, and Romberg disease. The application sites of hydroxyapatite cement were the forehead, malar area, chin, and paranasal area. A mean of 16 g (range, 5-50 g) of the hydroxyapatite cement was used. Postoperative infection, seroma, and migration of the implant were not observed during the follow-up period of 23 months. Rapidly hardening hydroxyapatite cement, Mimix, is easy to manipulate, promptly sclerotized, and can be replaced by living bone tissue, with a low complication rate. Therefore, it can be an optimal treatment that can be used instead of other conventional types of alloplastic materials used in facial contouring surgery.

  20. Increased risk of serious pneumococcal disease in patients with atopic conditions other than asthma.

    Jung, Ji A; Kita, Hirohito; Yawn, Barbara P; Boyce, Thomas G; Yoo, Kwang H; McGree, Michaela E; Weaver, Amy L; Wollan, Peter; Jacobson, Robert M; Juhn, Young J


    We reported an increased risk of serious pneumococcal disease (SPD) among patients with asthma. It is not known whether this is true for patients with other atopic conditions. To determine the relationship between atopic conditions other than asthma and SPD. The study subjects were residents of Rochester, Minn, who developed SPD between 1964 and 1983 and their 2 sex-matched and age-matched controls. We used a population-based computer-linked medical diagnosis system to identify all individuals with potential SPD. All records were reviewed by using explicit predetermined criteria for SPD. All individuals with atopic conditions were identified by the physician diagnoses including atopic dermatitis or eczema, allergic rhinitis, and hay fever documented in medical records. The associations between these atopic conditions and SPD were assessed by using conditional logistic regression. A total of 3941 records were reviewed, and we identified 174 SPD cases. Of these 174 cases, 50.6% were male, and 94.3% were Caucasian. Twenty-six (14.9%) of the SPD cases and 29 (8.3%) of the controls had atopy. Atopic conditions other than asthma were associated with an increased risk of SPD (odds ratio, 2.13; 95% CI, 1.04-4.35; P = .04) after adjusting for smoking status, previous high-risk conditions for SPD, educational status, and ethnicity. Like asthma, other atopic conditions, particularly atopic dermatitis, are associated with an increased risk of SPD. There may be a common immunogenetic mechanism underlying increased risk of SPD among individuals with either asthma or other atopic conditions. Our study findings need to be studied further. Copyright 2010 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.

  1. Increased tone-offset response in the lateral nucleus of the amygdala underlies trace fear conditioning.

    Kim, Namsoo; Kong, Mi-Seon; Jo, Kyeong Im; Kim, Eun Joo; Choi, June-Seek


    Accumulating evidence suggests that the lateral nucleus of the amygdala (LA) stores associative memory in the form of enhanced neural response to the sensory input following classical fear conditioning in which the conditioned stimulus (CS) and the unconditioned stimulus (US) are presented in a temporally continuous manner. However, little is known about the role of the LA in trace fear conditioning where the CS and the US are separated by a temporal gap. Single-unit recordings of LA neurons before and after trace fear conditioning revealed that the short-latency activity to the CS offset, but not that to the onset, increased significantly and accompanied the conditioned fear response. The increased short-latency activity was evident in two aspects: the number of offset-responsive neurons was increased and the latency of the neuronal response to the CS offset was shortened. On the contrary, changes in the firing rate to either the onset or the offset were negligible following unpaired presentations of the CS and US. In sum, our results suggest that increased synaptic efficacy in the CS offset pathway in the LA might underlie the association between temporally distant stimuli in trace fear conditioning.

  2. Conditional and continuous electrical stimulation increase cystometric capacity in persons with spinal cord injury.

    Horvath, Eric E; Yoo, Paul B; Amundsen, Cindy L; Webster, George D; Grill, Warren M


    Individuals with spinal cord injury (SCI) exhibit neurogenic detrusor overactivity (NDO) causing high intravesicle pressures and incontinence. The first aim was to measure changes in maximum cystometric capacity (MCC) evoked by electrical stimulation of the dorsal genital nerve (DGN) delivered either continuously or conditionally (only during bladder contractions) in persons with SCI. The second aim was to use the external anal sphincter electromyogram (EMG(EAS)) for real-time control of conditional stimulation. Serial filling cystometries were performed in nine volunteers with complete or incomplete supra-sacral SCI. Conditional stimulation was delivered automatically when detrusor pressure increased to 8-12 cmH(2)O above baseline. MCCs were measured for each treatment (continuous, conditional, and no stimulation) and compared using post-ANOVA Tukey HSD paired comparisons. Additional treatments in two subjects used the EMG(EAS) for automatic control of conditional stimulation. Continuous and conditional stimulation increased MCC by 63 +/- 73 ml (36 +/- 24%) and 74 +/- 71 ml (51 +/- 37%), respectively (P stimulation. There was no significant difference between MCCs for conditional and continuous stimulation, but conditional stimulation significantly reduced stimulation time (174 +/- 154 sec, or 27 +/- 17% of total time) as compared to continuous stimulation (469 +/- 269 sec, 100% of total time, P stimulation time (21 +/- 8% of total time). Conditional stimulation generates increases in bladder capacity while substantially reducing stimulation time. Furthermore, EMG(EAS) was successfully used as a real-time feedback signal to control conditional electrical stimulation in a laboratory setting. (c) 2009 Wiley-Liss, Inc.

  3. Analysis of the regimes in the scanner-based laser hardening process

    Martínez, S.; Lamikiz, A.; Ukar, E.; Calleja, A.; Arrizubieta, J. A.; Lopez de Lacalle, L. N.


    Laser hardening is becoming a consolidated process in different industrial sectors such as the automotive industry or in the die and mold industry. The key to ensure the success in this process is to control the surface temperature and the hardened layer thickness. Furthermore, the development of reliable scanners, based on moving optics for guiding high power lasers at extremely fast speeds allows the rapid motion of laser spots, resulting on tailored shapes of swept areas by the laser. If a scanner is used to sweep a determined area, the laser energy density distribution can be adapted by varying parameters such us the scanning speed or laser power inside this area. Despite its advantages in terms of versatility, the use of scanners for the laser hardening process has not yet been introduced in the thermal hardening industry because of the difficulty of the temperature control and possible non-homogeneous hardness thickness layers. In the present work the laser hardening process with scanning optics applied to AISI 1045 steel has been studied, with special emphasis on the influence of the scanning speed and the results derived from its variation, the evolution of the hardened layer thickness and different strategies for the control of the process temperature. For this purpose, the hardened material has been studied by measuring microhardness at different points and the shape of the hardened layer has also been evaluated. All tests have been performed using an experimental setup designed to keep a nominal temperature value using a closed-loop control. The tests results show two different regimes depending on the scanning speed and feed rate values. The experimental results conclusions have been validated by means of thermal simulations at different conditions.

  4. Microstructural analysis of ion-irradiation-induced hardening in inconel 718

    Hashimoto, N.; Hunn, J. D.; Byun, T. S.; Mansur, L. K.


    As an assessment for a possible accelerator beam line window material for the US Spallation Neutron Source (SNS) target, performance, radiation-induced hardening and microstructural evolution in Inconel 718 were investigated in both solution annealed (SA) and precipitation hardened (PH) conditions. Irradiations were carried out using 3.5 MeV Fe +, 370 keV He + and 180 keV H + either singly or simultaneously at 200 °C to simulate the damage and He/H production in the SNS target vessel wall. This resulted in systematic hardening in SA Inconel and gradual net softening in the PH material. TEM microstructural analysis showed the hardening was associated with the formation of small loop and faulted loop structures. Helium-irradiated specimens included more loops and cavities than Fe + ion-irradiated specimens. Softening of the PH material was due to dissolution of the γ '/γ ″ precipitates. High doses of helium were implanted in order to study the effect of high retention of gaseous transmutation products. Simultaneous with the hardening and/or softening due to the displacement damage cascade, helium filled cavities produced additional hardening at high concentrations.

  5. Time-dependent 3-D modelling of laser surface heating for the hardening of metallic materials

    Colombo, V.; Mentrelli, A.; Trombetti, T.


    A numerical code for the time-dependent three-dimensional modelling of the laser surface heating for the hardening of metallic materials has been developed by the authors. The temperature-dependence of the thermal properties of the material (stainless steel) is taken into account in the frame of a heating process that doesn’t lead to material melting or evaporation. Calculations have been carried out for various dimensions of the parallelepiped-shaped and of the square-shaped spot of the laser beam, as well as for different scanning velocity and for different levels of the laser source power. Various patterns of the laser spot path have also been studied, including a single-pass hardening pattern, a double-pass hardening pattern with and without overlapping, multiple discontinuous and continuous hardening patterns and spiral hardening patterns. The presented results show how the proposed model can be usefully employed in the prediction of the time-evolution of temperature distribution which arises in the workpiece as a consequence of the laser-workpiece interaction under operating conditions typically encountered in industrial applications of the laser hardening process.

  6. Increased biomass yield of Lactococcus lactis during energetically limited growth and respiratory conditions

    Købmann, Brian Jensen; Blank, Lars Mathias; Solem, Christian


    Lactococcus lactis is known to be capable of respiration under aerobic conditions in the presence of haemin. In the present study the effect of respiration on ATP production during growth on different sugars was examined. With glucose as the sole carbon source, respiratory conditions in L. lactis...... MG1363 resulted in only a minor increase, 21%, in biomass yield. Since ATP production through substrate-level phosphorylation was essentially identical with and without respiration, the increased biomass yield was a result of energy-saving under respiratory conditions estimated to be 0.4 mol of ATP....../mol of glucose. With maltose as the energy source, the increase in biomass yield amounted to 51% compared with an aerobic culture that lacked haemin. This higher ATP yield was obtained by redirecting pyruvate metabolism from lactate to acetate production, and from savings through respiration. However, even after...

  7. Durability of High Performance Color Hardener

    MA Bao-guo; DONG Rong-zhen; ZHU Hong-bo; ZHANG Li; JIAN Shou-wei


    The properties of high performance color hardener (HPCH) and the mechanism were studied.HPCH is a composite system, which is composed of cementitious and auxiliary cementing materials, composite additives, abrasion resistance component (aggregate) and pigment. The porosity and pore structure of the material are obviously improved due to the activation, filling and adsorption of auxiliary cementing materials, thus resulting in a great increase of binding capacity for ions in HPCH and the obstacles of ion migrating.The density of material structure, bonding capacity of cementitious material to the abrasion-resisting component and the corrosion resistance are greatly and effectively improved by adding the auxiliary cementing materials and compound additives. According to the tests of dry shrinkage, sulphate resistance, chloride permeability and Ca(OH)2 content distribution, the property superiority of HPCH is analyzed.The mechanism of materials modification of HPCH is explained from the microscopic point of view by testing the pore structure and pore distribution via the mercury intrusion pressure method.

  8. Open Source Radiation Hardened by Design Technology

    Shuler, Robert


    The proposed technology allows use of the latest microcircuit technology with lowest power and fastest speed, with minimal delay and engineering costs, through new Radiation Hardened by Design (RHBD) techniques that do not require extensive process characterization, technique evaluation and re-design at each Moore's Law generation. The separation of critical node groups is explicitly parameterized so it can be increased as microcircuit technologies shrink. The technology will be open access to radiation tolerant circuit vendors. INNOVATION: This technology would enhance computation intensive applications such as autonomy, robotics, advanced sensor and tracking processes, as well as low power applications such as wireless sensor networks. OUTCOME / RESULTS: 1) Simulation analysis indicates feasibility. 2)Compact voting latch 65 nanometer test chip designed and submitted for fabrication -7/2016. INFUSION FOR SPACE / EARTH: This technology may be used in any digital integrated circuit in which a high level of resistance to Single Event Upsets is desired, and has the greatest benefit outside low earth orbit where cosmic rays are numerous.

  9. On Analytical Solutions to Beam-Hardening

    Rigaud, G.


    When polychromatic X-rays propagate through a material, for instance in computerized tomography (CT), low energy photons are more attenuated resulting in a "harder" beam. The beam-hardening phenomenon breaks the monochromatic radiation model based on the Radon transform giving rise to artifacts in CT reconstructions to the detriment of visual inspection and automated segmentation algorithms. We propose first a simplified analytic representation for the beam-hardening. Besides providing a general understanding of the phenomenon, this model proposes to invert the beam-hardening effect for homogeneous objects leading to classical monochromatic data. For heterogeneous objects, no analytical reconstruction of the density can be derived without more prior information. However, the beam-hardening is shown to be a smooth operation on the data and thus to preserve the encoding of the singularities of the attenuation map within the data. A microlocal analysis encourages the use of contour extraction methods to solve partially the beam-hardening effect even for heterogeneous objects. The application of both methods, exact analytical solution for homogeneous objects and feature extraction for heterogeneous ones, on real data demonstrates their relevancy and efficiency.

  10. Intraperitoneal sertraline and fluvoxamine increase contextual fear conditioning but are without effect on overshadowing between cues.

    Cassaday, H J; Thur, K E


    Treatment with selective serotonin reuptake inhibitors (SSRIs) can reduce contextual conditioning. Since contexts comprise a variety of potentially competing cues, impaired overshadowing may provide an account of such effects. The present study therefore compared the effects of two SSRIs on overshadowing and contextual conditioning, testing suppression of an ongoing behavioral response (licking) by cues previously paired with foot shock. Conditioning to a 5 s light stimulus was reduced when it was presented in compound with a 5 s noise, thus overshadowing was demonstrated. In two experiments, this overshadowing was unaffected by treatment with either sertraline or fluvoxamine. However, unconditioned suppression to the noise (tested in a control group previously conditioned to the light alone) was reduced after sertraline (10 mg/kg, i.p.). The successful demonstration of overshadowing required the use of a second conditioning session or an additional conditioning trial within the same conditioning session. Neither weak nor strong overshadowing (of the light by the tone) was affected by any drug treatment. Moreover, counter to prediction, conditioning to contextual cues was increased rather than impaired by treatment with sertraline (10 mg/kg, i.p.) and fluvoxamine (30 mg/kg, i.p.).

  11. Control technology for surface treatment of materials using induction hardening

    Kelley, J.B.; Skocypec, R.D. [Sandia National Labs., NM (United States)


    In the industrial and automotive industries, induction case hardening is widely used to provide enhanced strength, wear resistance, and toughness in components made from medium and high carbon steels. The process uses significantly less energy than competing batch process, is environmentally benign, and is a very flexible in-line manufacturing process. As such, it can directly contribute to improved component reliability, and the manufacture of high-performance lightweight parts. However, induction hardening is not as widely used as it could be. Input material and unexplained process variations produce significant variation in product case depth and quality. This necessitates frequent inspection of product quality by destructive examination, creates higher than desired scrap rates, and causes de-rating of load stress sensitive components. In addition, process and tooling development are experience-based activities, accomplished by trial and error. This inhibits the use of induction hardening for new applications, and the resultant increase in energy efficiency in the industrial sectors. In FY96, a Cooperative Research and Development Agreement under the auspices of the Technology Transfer Initiative and the Partnership for a New Generation of Vehicles was completed. A multidisciplinary team from Sandia National Labs and Delphi Saginaw Steering Systems investigated the induction hardening by conducting research in the areas of process characterization, computational modeling, materials characterization, and high speed data acquisition and controller development. The goal was to demonstrate the feasibility of closed-loop control for a specific material, geometry, and process. Delphi Steering estimated annual savings of $2-3 million per year due to reduced scrap losses, inspection costs, and machine down time if reliable closed-loop control could be achieved. A factor of five improvement in process precision was demonstrated and is now operational on the factory floor.

  12. Press Hardening Steel (PHS): a new coating and process technology

    Faderl, J. [voestalpine Stahl Linz GmbH (Austria); Vehof, R. [Polynorm N.V., Bundschoten (Netherlands)


    Press hardening technology has been known for many years. Increased requirements with respect to safety and light weight construction of the steel body for cars and trucks force the automotive industry to use high strength steels more and more. Strength levels up to 1000 MPa can be provided with AHSS grades. Above 1000 MPa, these steel grades are coming to their limit with respect to strength vs. formability balance. PHS is a very attractive alternative concept. Hardenable 22MnB5 has been supplied - uncoated - for a long time. To avoid decarburization during heat treatment and to improve corrosion behaviour hot dip aluminized 22MnB5 was introduced to the market. Both materials, uncoated and hot dip aluminized, do not provide cathodic corrosion protection without postcoating (sheradizing..). In the last two years an improved press hardening technology and a zinc based coating providing cathodic protection was developed by voestalpine. Some results about strength homogeneity, formability, corrosion behaviour of this voestalpine-PHS technology will be presented in the paper. (orig.)

  13. Plasma methods of obtainment of multifunctional composite materials, dispersion-hardened by nanoparticles

    Sizonenko, O. N.; Grigoryev, E. G.; Zaichenko, A. D.; Pristash, N. S.; Torpakov, A. S.; Lipyan, Ye V.; Tregub, V. A.; Zholnin, A. G.; Yudin, A. V.; Kovalenko, A. A.


    The new approach in developed plasma methods consists in that dispersionhardening additives (TiC, TiB2 in particular) are not mechanically added to powder mixture as additional component, as in conventional methods, but are instead synthesized during high voltage electric discharges (HVED) in disperse system “hydrocarbon liquid - powder” preservation of ultrafine structure is ensured due to use of spark plasma sintering (SPS) as a consolidation method. HVED in disperse system “hydrocarbon liquid - powder” due to impact of plasma discharge channel, electromagnetic fields, shock waves mechanical impact, hydro flows and volume microcavitation leads to synthesis of nanocarbon, metal powders dispersion and synthesis of micro- (from 10-6 to 10-7 m) and nanosized (from 10-7 to 10-9 m) composite powders of hardening phases. SPS is the passage of pulsed current (superposition of direct and alternating current) through powder with the simultaneous mechanical compressing. The formation of plasma is initiated in gaseous phase that fills gaps between particles. SPS allows targeted control of grain growth rate and thus allows obtainment of multifunctional composite materials dispersion hardened by nanoparticles. Processes of HVED synthesis of micro- and nanosized powders of new compositions from elemental metal powders and their mixtures with the subsequent application of high-speed SPS of obtained powders create conditions for increase of strength (by 10 - 20%), hardness and wear-resistance (by 30 - 60%) of obtained materials.

  14. Incentive learning for morphine-associated stimuli during protracted abstinence increases conditioned drug preference.

    Smith, Rachel J; Aston-Jones, Gary


    Previous studies from our laboratory found that rats express increased preference for drug-paired stimuli following 2 or 5 weeks of protracted abstinence from chronic drug exposure as compared with naive animals. Here, we show that this increased morphine place preference depends upon experiencing drug-stimulus pairings specifically in the abstinent state, indicating a critical role for incentive learning. Male Sprague Dawley rats were initially conditioned for morphine place preference (8 mg/kg) and then made dependent on morphine (by subcutaneous morphine pellets) and subjected to forced abstinence. Place preference was tested every 1-2 weeks with no additional drug-cue conditioning. In this paradigm, there was no difference between morphine-pelleted (dependent) and placebo-pelleted (non-dependent) rats in place preference at any time during abstinence (up to 6 weeks). However, these same morphine-pelleted rats expressed significantly increased preference when they were subsequently re-conditioned for morphine place preference during protracted abstinence. Placebo-pelleted rats did not show enhanced preference after re-conditioning. These findings reveal that incentive learning has a key role in increased morphine place preference when drug is experienced during protracted abstinence. This indicates that incentive learning is involved not only in instrumental responding (as previously reported), but also in updating Pavlovian-conditioned responses to morphine-associated stimuli. Therefore, enhanced morphine preference is not a direct consequence of the negative affective state of abstinence, but instead reflects increased acquisition of morphine-stimulus associations during abstinence. These results indicate that, during the development of addiction in humans, drug-associated stimuli acquire increasingly stronger incentive properties each time they are re-experienced.

  15. Long-term behavioral sensitization to apomorphine is independent of conditioning and increases conditioned pecking, but not preference, in pigeons.

    Anselme, Patrick; Edeş, Neslihan; Tabrik, Sepideh; Güntürkün, Onur


    When rodents are given a free choice between a variable option and a constant option, they may prefer variability. This preference is even sometimes increased following repeated administration of a dopamine agonist. The present study was the first to examine preference for variability under the systemic administration of a dopamine agonist, apomorphine (Apo), in birds. Experiment 1 tested the drug-free preference and the propensity to choose of pigeons for a constant over a variable delay. It appeared that they preferred and decided more quickly to peck at the optimal delay option. Experiment 2 assessed the effects of a repeated injection of Apo on delay preference, in comparison with previous control tests within the same individuals. Apo treatment might have decreased the number of pecks at the constant option across the different experimental phases, but failed to induce a preference for the variable option. In Experiment 3, two groups of pigeons (Apo-sensitized and saline) were used in order to avoid inhomogeneity in treatments. They had to choose between a 50% probability option and a 5-s delay option. Conditioned pecking and the propensity to choose were higher in the Apo-sensitized pigeons, but, in each group, the pigeons showed indifference between the two options. This experiment also showed that long-term behavioral sensitization to Apo can occur independently of a conditioning process. These results suggest that Apo sensitization can enhance the attractiveness of conditioned cues, while having no effect on the development of a preference for variable-delay and probabilistic schedules of reinforcement. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. A Temporal-Specific and Transient cAMP Increase Characterizes Odorant Classical Conditioning

    Cui, Wen; Smith, Andrew; Darby-King, Andrea; Harley, Carolyn W.; McLean, John H.


    Increases in cyclic adenosine monophosphate (cAMP) are proposed to initiate learning in a wide variety of species. Here, we measure changes in cAMP in the olfactory bulb prior to, during, and following a classically conditioned odor preference trial in rat pups. Measurements were taken up to the point of maximal CREB phosphorylation in olfactory…

  17. 40 CFR 86.090-5 - General standards; increase in emissions; unsafe conditions.


    ... light or heavy duty motor vehicle equipped with an engine certified to the nonroad provision of 40 CFR... standards; increase in emissions; unsafe conditions. (a)(1) Every new motor vehicle (or new motor vehicle... with respect to any Otto-cycle or diesel heavy-duty vehicle which uses an engine which has not...

  18. Modeling of Irradiation Hardening of Polycrystalline Materials

    Li, Dongsheng; Zbib, Hussein M.; Garmestani, Hamid; Sun, Xin; Khaleel, Mohammad A.


    High energy particle irradiation of structural polycrystalline materials usually produces irradiation hardening and embrittlement. The development of predict capability for the influence of irradiation on mechanical behavior is very important in materials design for next generation reactors. In this work a multiscale approach was implemented to predict irradiation hardening of body centered cubic (bcc) alpha-iron. The effect of defect density, texture and grain boundary was investigated. In the microscale, dislocation dynamics models were used to predict the critical resolved shear stress from the evolution of local dislocation and defects. In the macroscale, a viscoplastic self-consistent model was applied to predict the irradiation hardening in samples with changes in texture and grain boundary. This multiscale modeling can guide performance evaluation of structural materials used in next generation nuclear reactors.

  19. An Anisotropic Hardening Model for Springback Prediction

    Zeng, Danielle; Xia, Z. Cedric


    As more Advanced High-Strength Steels (AHSS) are heavily used for automotive body structures and closures panels, accurate springback prediction for these components becomes more challenging because of their rapid hardening characteristics and ability to sustain even higher stresses. In this paper, a modified Mroz hardening model is proposed to capture realistic Bauschinger effect at reverse loading, such as when material passes through die radii or drawbead during sheet metal forming process. This model accounts for material anisotropic yield surface and nonlinear isotropic/kinematic hardening behavior. Material tension/compression test data are used to accurately represent Bauschinger effect. The effectiveness of the model is demonstrated by comparison of numerical and experimental springback results for a DP600 straight U-channel test.

  20. Induction surface hardening of hard coated steels

    Pantleon, Karen; Kessler, Olaf; Hoffmann, Franz


    -process is the high deposition temperature, consequently the properties of steel substrates are negatively influenced. Therefore, a subsequent heat treatment of the coated steels is necessary to restore the properties of steels ready for operation. Induction surface hardening is used as a method of heat treatment....... The effect of induction surface hardening on the properties of the coating-substrate-systems is mainly characterized using investigations of microstructure and chemical composition as well as measurements of hardness and residual stresses in dependence on the distance from the surface. Furthermore......, the scratch test is used to estimate critical loads for cohesive and adhesive failure of the coatings. Additionally, distortion measurements are carried out. The results emphasize the advantage of induction surface hardening as a method of subsequent heat treatment of CVD-coated steels....

  1. Influence of cyclic temperature changes on the microstructure of AISI 4140 after laser surface hardening

    Miokovic, T. [Institute of Materials Science and Engineering I, University of Karlsruhe, 76131 Karlsruhe (Germany); Schulze, V. [Institute of Materials Science and Engineering I, University of Karlsruhe, 76131 Karlsruhe (Germany)]. E-mail:; Voehringer, O. [Institute of Materials Science and Engineering I, University of Karlsruhe, 76131 Karlsruhe (Germany); Loehe, D. [Institute of Materials Science and Engineering I, University of Karlsruhe, 76131 Karlsruhe (Germany)


    In recent years laser surface hardening using pulsed laser sources has become an increasingly established technology in engineering industry and has opened up wider possibilities for the application of selective surface hardening. However, the choice of the process parameters is generally based on experience rather than on their empirical influence on the resulting microstructure, and for hardening processes with cyclic temperature changes, almost no correlations between process parameters and hardening results are known. Therefore, some problems regarding the choice of the process parameters and their influence on the resulting microstructure still remain. In particular, there is a lack of data concerning the effect of cyclic temperature changes on hardening. To facilitate process optimization, this paper deals with a detailed characterization of the microstructures created in quenched and tempered AISI 4140 (German grade 42CrMo4) steel following a temperature-dependent laser surface hardening treatment. The structure properties were obtained from microhardness measurements, scanning electron microscopy investigations and X-ray diffraction analysis of retained austenite.

  2. A novel radiation hardened by design latch

    Huang Zhengfeng; Liang Huaguo


    Due to aggressive technology scaling, radiation-induced soft errors have become a serious reliability concern in VLSI chip design. This paper presents a novel radiation hardened by design latch with high single-event-upset (SEU) immunity. The proposed latch can effectively mitigate SEU by internal dual interlocked scheme. The propagation delay, power dissipation and power delay product of the presented latch are evaluated by detailed SPICE simulations. Compared with previous SEU-hardening solutions such as TMR-Latch, the presented latch is more area efficient, delay and power efficient. Fault injection simulations also demonstrate the robustness of the presented latch even under high energy particle strikes.

  3. Radiation hardening revisited: Role of intracascade clustering

    Singh, B.N.; Foreman, A.J.E.; Trinkaus, H.


    be explained in terms of conventional dispersed-barrier hardening because (a) the grown-in dislocations are not free, and (b) irradiation-induced defect clusters are not rigid indestructible Orowan obstacles. A new model called 'cascade-induced source hardening' is presented where glissile loops produced...... directly in cascades are envisaged to decorate the grown-in dislocations so that they cannot act as dislocation sources. The upper yield stress is related to the breakaway stress which is necessary to pull the dislocation away from the clusters/loops decorating it. The magnitude of the breakaway stress has...

  4. Plasma Arc Surface Hardening Robot Technology


    In national economy and national defense, a lot of ma chine components become worthless early because of wear and tear and corrode. It leads to huge loss of resource and material. Surface hardening of the steel cou ld form a hard, wearable, corrode-resisting layer on the surface to enhance the mechanical property of the machine component. From 1980s, there is a new method of surface hardening that is heating with plasma arc. It overcomes the shortage of old methods and is adopted in automotive product ...

  5. Investigation of Hardened Filling Grout Samples

    Sørensen, Eigil V.

     Suzlon Wind Energy A/S requested on August 28, 2007 an investigation of 2 samples of a hardened filling grout to be carried out, comprising drilling and strength determination of 4 test cylinders, and description of the surface characteristics of the samples....... Suzlon Wind Energy A/S requested on August 28, 2007 an investigation of 2 samples of a hardened filling grout to be carried out, comprising drilling and strength determination of 4 test cylinders, and description of the surface characteristics of the samples....

  6. Induction surface hardening of hard coated steels

    Pantleon, Karen; Kessler, Olaf; Hoffmann, Franz


    . The effect of induction surface hardening on the properties of the coating-substrate-systems is mainly characterized using investigations of microstructure and chemical composition as well as measurements of hardness and residual stresses in dependence on the distance from the surface. Furthermore......, the scratch test is used to estimate critical loads for cohesive and adhesive failure of the coatings. Additionally, distortion measurements are carried out. The results emphasize the advantage of induction surface hardening as a method of subsequent heat treatment of CVD-coated steels....

  7. Rationale simplified hardening training and recreational complexes future teachers

    Verbludov I.B.


    Full Text Available Distribution in the modern world epidemiological diseases are influenza and acute respiratory viral infections requires a search for simplified, effective preventive means. The main direction of prevention of these diseases is to strengthen and enhance the activities of the immune system. Strengthening the protective systems of the body is directly related to the constant holding of different types of hardening. This study illustrates the possibility of using quenching air and water in the independent exercise training and recreational facilities in all conditions of students.

  8. The 10 Conditions That Increased Vermont's Readiness to Implement Statewide Health System Transformation.

    Grembowski, David; Marcus-Smith, Miriam


    Following an arduous, 6-year policy-making process, Vermont is the first state implementing a unified, statewide all-payer integrated delivery system with value-based payment, along with aligned medical and social service reforms, for almost all residents and providers in a state. Commercial, Medicare, and Medicaid value-based payment for most Vermonters will be administered through a new statewide accountable care organization in 2018-2022. The purpose of this article is to describe the 10 conditions that increased Vermont's readiness to implement statewide system transformation. The authors reviewed documents, conducted internet searches of public information, interviewed key informants annually in 2014-2016, cross-validated factual and narrative interpretation, and performed content analyses to derive conditions that increased readiness and their implications for policy and practice. Four social conditions (leadership champions; a common vision; collaborative culture; social capital and collective efficacy) and 6 support conditions (money; statewide data; legal infrastructure; federal policy promoting payment reform; delivery system transformation aligned with payment reform; personnel skilled in system reform) increased Vermont's readiness for system transformation. Vermont's experience indicates that increasing statewide readiness for reform is slow, incremental, and exhausting to overcome the sheer inertia of large fee-based systems. The new payments may work because statewide, uniform population-based payment will affect the health care of almost all Vermonters, creating statewide, uniform provider incentives to reduce volume and making the current fee-based system less viable. The conditions for readiness and statewide system transformation may be more likely in states with regulated markets, like Vermont, than in states with highly competitive markets.

  9. Increase in expression level of alpha-tubulin gene in Arabidopsis seedlings under hypergravity conditions.

    Saito, Yuka; Soga, Kouichi; Wakabayashi, Kazuyuki; Hoson, Takayuki


    Under hypergravity conditions, elongation growth of plant shoots is suppressed. The analysis of the changes in gene expression by hypergravity treatment in Arabidopsis hypocotyls by the differential display method showed that a gene encoding alpha-tubulin, which is a component of microtubules, was up-regulated by hypergravity. In Arabidopsis six genes encoding alpha-tubulin (TUA1-TUA6) have been identified. In the present study, we examined the dose-response and the time course relations of the changes in the expression of all six alpha-tubulin genes in Arabidopsis hypocotyls grown under hypergravity conditions. The expression levels of all six alpha-tubulin genes, TUA1-TUA6, were increased by increasing gravity, although the extent was variable among genes. The increase in expression of all alpha-tubulin genes was detected within a few hours, when the seedlings grown at 1 g were transferred to 300 g condition. These results suggest that Arabidopsis hypocotyls regulate the expression level of six alpha-tubulin genes promptly in response to gravity stimuli. The increase in the amount of microtubules due to the activation of tubulin gene expression may be involved in the regulation by gravity signal of shoot growth.

  10. HTPro: Low-temperature Surface Hardening of Stainless Steel

    Christiansen, Thomas Lundin; Somers, Marcel A. J.


    Low-temperature surface hardening of stainless steel provides the required performance properties without affecting corrosion resistance.......Low-temperature surface hardening of stainless steel provides the required performance properties without affecting corrosion resistance....

  11. Self hardening property of Botswana fly ash | Sahu | Botswana ...

    Self hardening property of Botswana fly ash. ... In the present investigation, an effort has been made to study the self hardening property of Botswana fly ash by ... This will encourage the use of fly ash economically as a construction material.

  12. Feasibility Studies on Underwater Laser Surface Hardening Process

    Biao Jin


    Full Text Available Laser surface hardening process is a very promising hardening method for ferrous and nonferrous alloys where transformations occur during cooling after laser melting in the solid state. This study experimentally characterizes laser surface hardening of tool steel in both water and air. For the underwater operation, laser surface scanning is performed over the tool steel surface which is immersed in water. The laser surface hardening tests are performed with a maximum 200 W fiber laser with a Gaussian distribution of energy in the beam. For the surface hardening, single-track melting experiment which sequentially scans elongated path of single line has been performed. As the hardened depth depends on the thermal conductivity of the material, the surface temperature and the penetration depth may be varied by underwater laser processing. The feasibility of underwater laser surface hardening process is discussed on the basis of average hardness level and hardened bead shape.

  13. Conditioned medium from feeder STO cells increases the attachment of mouse embryonic stem cells.

    Amano, Kenichiro; Furuno, Tadahide; Nakanishi, Mamoru


    Mouse embryonic stem (ES) cell lines, which were established by culturing on feeder cells, have usually been cultured without feeder cells in the presence of leukemia inhibitory factor. However, proliferating rate of ES cells in the condition is often lower than that with feeder cells. Here, we found that conditioned medium (CM) from feeder cells (STO cells) increased the number of undifferentiated cells in a culture dish by promoting attachment of ES cells. The attached cells were increased in 4 h after replating ES cells in the presence of CM from STO cells, and they formed flat colonies composed of undifferentiated cells. This culture system with CM from feeder cells is useful in preparing a large number of well-defined ES cells. In addition, from present experiments we found that the dish double-coated with gelatin and CM was extremely useful for culturing ES cells.

  14. Loading rate increases during barefoot running in habitually shod runners: Individual responses to an unfamiliar condition.

    Tam, Nicholas; Astephen Wilson, Janie L; Coetzee, Devon R; van Pletsen, Leanri; Tucker, Ross


    The purpose of this study was to examine the effect of barefoot running on initial loading rate (LR), lower extremity joint kinematics and kinetics, and neuromuscular control in habitually shod runners with an emphasis on the individual response to this unfamiliar condition. Kinematics and ground reaction force data were collected from 51 habitually shod runners during overground running in a barefoot and shod condition. Joint kinetics and stiffness were calculated with inverse dynamics. Inter-individual initial LR variability was explored by separating individuals by a barefoot/shod ratio to determine acute responders/non-responders. Mean initial LR was 54.1% greater in the barefoot when compared to the shod condition. Differences between acute responders/non-responders were found at peak and initial contact sagittal ankle angle and at initial ground contact. Correlations were found between barefoot sagittal ankle angle at initial ground contact and barefoot initial LR. A large variability in biomechanical responses to an acute exposure to barefoot running was found. A large intra-individual variability was found in initial LR but not ankle plantar-dorsiflexion between footwear conditions. A majority of habitually shod runners do not exhibit previously reported benefits in terms of reduced initial LRs when barefoot. Lastly, runners who increased LR when barefoot reduced LRs when wearing shoes to levels similar seen in habitually barefoot runners who do adopt a forefoot-landing pattern, despite increased dorsiflexion.

  15. Mexico’s conditional cash transfer programme increases cesarean section rates among the rural poor


    Background: Caesarean section rates are increasing in Mexico and Latin America. This study evaluates the impact of a large-scale, conditional cash transfer programme in Mexico on caesarean section rates. The programme provides cash transfers to participating low income, rural households in Mexico conditional on accepting health care and nutrition supplements. Methods: The primary analyses uses retrospective reports from 979 women in poor rural communities participating in an effectiveness study and randomly assigned to incorporation into the programme in 1998 or 1999 across seven Mexican states. Using multivariate and instrumental variable analyses, we estimate the impact of the programme on caesarean sections and predict the adjusted mean rates by clinical setting. Programme participation is measured by beneficiary status, programme months and cash transfers. Results: More than two-thirds of poor rural women delivered in a health facility. Beneficiary status is associated with a 5.1 percentage point increase in caesarean rates; this impact increases to 7.5 percentage points for beneficiaries enrolled in the programme for ≥6 months before delivery. Beneficiaries had significantly higher caesarean delivery rates in social security facilities (24.0 compared with 5.6% among non-beneficiaries) and in other government facilities (19.3 compared with 9.5%). Conclusion: The Oportunidades conditional cash transfer programme is associated with higher caesarean section rates in social security and government health facilities. This effect appears to be driven by the increases in disposable income from the cash transfer. These findings are relevant to other countries implementing conditional cash transfer programmes and health care requirements. PMID:19933778

  16. Mexico's conditional cash transfer programme increases cesarean section rates among the rural poor.

    Barber, Sarah L


    Caesarean section rates are increasing in Mexico and Latin America. This study evaluates the impact of a large-scale, conditional cash transfer programme in Mexico on caesarean section rates. The programme provides cash transfers to participating low income, rural households in Mexico conditional on accepting health care and nutrition supplements. The primary analyses uses retrospective reports from 979 women in poor rural communities participating in an effectiveness study and randomly assigned to incorporation into the programme in 1998 or 1999 across seven Mexican states. Using multivariate and instrumental variable analyses, we estimate the impact of the programme on caesarean sections and predict the adjusted mean rates by clinical setting. Programme participation is measured by beneficiary status, programme months and cash transfers. More than two-thirds of poor rural women delivered in a health facility. Beneficiary status is associated with a 5.1 percentage point increase in caesarean rates; this impact increases to 7.5 percentage points for beneficiaries enrolled in the programme for >or=6 months before delivery. Beneficiaries had significantly higher caesarean delivery rates in social security facilities (24.0 compared with 5.6% among non-beneficiaries) and in other government facilities (19.3 compared with 9.5%). The Oportunidades conditional cash transfer programme is associated with higher caesarean section rates in social security and government health facilities. This effect appears to be driven by the increases in disposable income from the cash transfer. These findings are relevant to other countries implementing conditional cash transfer programmes and health care requirements.

  17. Feasibility Studies on Underwater Laser Surface Hardening Process

    Biao Jin; Min Li; TaeWoo Hwang; YoungHoon Moon


    Laser surface hardening process is a very promising hardening method for ferrous and nonferrous alloys where transformations occur during cooling after laser melting in the solid state. This study experimentally characterizes laser surface hardening of tool steel in both water and air. For the underwater operation, laser surface scanning is performed over the tool steel surface which is immersed in water. The laser surface hardening tests are performed with a maximum 200 W fiber laser with a ...



    The invention relates to case-hardening of a stainless steel article by means of gas including carbon and/or nitrogen, whereby carbon and/or nitrogen atoms diffuse through the surface into the article. The method includes activating the surface of the article, applying a top layer on the activated...

  19. Instabilities in power law gradient hardening materials

    Niordson, Christian Frithiof; Tvergaard, Viggo


    Tension and compression instabilities are investigated for specimens with dimensions in the micron range. A finite strain generalization of a higher order strain gradient plasticity theory is implemented in a finite element scheme capable of modeling power law hardening materials. Effects...

  20. Numerical investigation of the effect of friction conditions to increase die life

    Mutlu, M. O.; Guleryuz, C. G.; Parlar, Z.


    The standard die materials in aluminium extrusion offer good mechanical properties like high tempering resistance, high strength and ductility. On the other hand, they struggle with the problem of sliding wear. As a result, there is a growing interest in using surface treatment techniques to increase the wear resistance of extrusion dies. In this study, it is aimed to observe the effects of the different friction conditions on material flow and contact pressure in extrusion process. These friction conditions can be obtained with the application of a variety of surface treatment. In this way, it is expected to decrease the friction force on the die bearing area and to increase the homogeneity of the material flow which will result in the increase of the quality of the extrudate as well as the improvement of the process economically by extending die life. For this purpose, an extrusion process is simulated with a finite element software. A die made of 1.2344 hot work tool steel-commonly used die material for aluminium extrusion process- has been modelled and Al 1100 alloy used as billet material. Various friction factor values defined on the die surface under the same process parameters and effects of changing frictional conditions on the die and the extrusion process have been discussed.

  1. Commentary: Air-conditioning as a risk for increased use of healthservices

    Mendell, Mark J.


    In this issue of the journal, Preziosi et al. [2004] report the first study to assess differences in the utilization of health care related to the presence of air-conditioning in office workplaces. Although the study was simple and cross-sectional, the data variables from questionnaires, and the findings subject to a variety of questions, the findings are striking enough to deserve clarification. The study used a large random national sample of French women assembled for another purpose (to study antioxidant nutrients and prevention of cancer and cardiovascular disease). Participants reported health services and health events in monthly questionnaires over 1 year, and in one questionnaire in the middle of that period also reported whether air-conditioning was in use at their workplace. Fifteen percent of participants reported air-conditioning at work. Analyses adjusting for age and smoking status of participants found increases in most outcomes assessed: use of specific kinds of physicians, sickness absence, and hospital stays. While the increases in odds ratios (OR) and 95% confidence intervals (CI) were statistically significant for only otorhinolaryngology [OR (95% CI) = 2.33 (1.35-4.04)] and sickness absence [1.70 (1.13-2.58)], other increases were notable--dermatology [1.6 (0.98-2.65)]; hospital stay [1.51 (0.92-2.45)], and pneumonology [2.10 (0.65-6.82)]. The least elevated outcomes were for general practice medicine [0.99 (0.65-1.48)] and global medical visits [1.18 (0.67-2.07)]. [Preziosi et al., 2004 ,(Table 2)] Odds ratios for relatively common health outcomes often lie farther from the null than the risk ratios most useful for quantifying the increase in risk. Risk ratios, or prevalence ratios (PRs, the equivalent measure of effect for cross-sectional data), have seldom been used because of the convenience and availability of logistic regression models that estimate odds ratios. With baseline prevalences ranging up to 85.7% in the data from Preziosi et

  2. Increased 30-Day Emergency Department Revisits Among Homeless Patients with Mental Health Conditions

    Chun Nok Lam


    Full Text Available Introduction: Patients with mental health conditions frequently use emergency medical services. Many suffer from substance use and homelessness. If they use the emergency department (ED as their primary source of care, potentially preventable frequent ED revisits and hospital readmissions can worsen an already crowded healthcare system. However, the magnitude to which homelessness affects health service utilization among patients with mental health conditions remains unclear in the medical community. This study assessed the impact of homelessness on 30-day ED revisits and hospital readmissions among patients presenting with mental health conditions in an urban, safety-net hospital. Methods: We conducted a secondary analysis of administrative data on all adult ED visits in 2012 in an urban safety-net hospital. Patient demographics, mental health status, homelessness, insurance coverage, level of acuity, and ED disposition per ED visit were analyzed using multilevel modeling to control for multiple visits nested within patients. We performed multivariate logistic regressions to evaluate if homelessness moderated the likelihood of mental health patients’ 30-day ED revisits and hospital readmissions. Results: Study included 139,414 adult ED visits from 92,307 unique patients (43.5±15.1 years, 51.3% male, 68.2% Hispanic/Latino. Nearly 8% of patients presented with mental health conditions, while 4.6% were homeless at any time during the study period. Among patients with mental health conditions, being homeless contributed to an additional 28.0% increase in likelihood (4.28 to 5.48 odds of 30-day ED revisits and 38.2% increase in likelihood (2.04 to 2.82 odds of hospital readmission, compared to non-homeless, non-mental health (NHNM patients as the base category. Adjusted predicted probabilities showed that homeless patients presenting with mental health conditions have a 31.1% chance of returning to the ED within 30-day post discharge and a 3

  3. A New Method of Hardening Inner Wall of Long Pipe


    A new laser inner wall hardening method for long pipe mas introduced. The system combines laser surface hardening with robot moving in pipeline. Some craft experiments have been done with this system and optimum parameters of laser hardening have been found.

  4. Micro-mechanical modelling of ductile failure in 6005A aluminium using a physics based strain hardening larw including stage IV

    Simar, Aude; Nielsen, Kim Lau; de Meester, Bruno


    The strain hardening and damage behaviour of isothermally heat treated 6005A aluminium is investigated in order to link the thermal treatment conditions, microstructure and fracture strain. The need for a plastic flow rule involving a stage IV hardening at large strain was found essential...

  5. Increased rate of force development of elbow flexors by antagonist conditioning contraction.

    Kamimura, Takashi; Yoshioka, Koichi; Ito, Susumu; Kusakabe, Tatsumi


    The effects of isometric antagonist conditioning contraction (ACC) at various durations and intensities on the contractile force, electromyographic (EMG) amplitude, and their rates of rise of elbow flexor muscles were examined in healthy participants. In particular, we focused on the change in the maximum rate of initial force development of agonists (dFagonist/dt(max)), which was evaluated by subtracting antagonist force decaying from apparent initial force development. While the ACC caused no statistically significant effect on the average force during elbow flexion, dFagonist/dt(max) was significantly increased by the ACC of short durations (1-2s) and large intensities. Similarly, the ACC did not affect the root mean square EMG amplitude of biceps brachii during elbow flexion, but significantly increased the maximum rate of rise of the absolute EMG amplitude (dE/dt(max)). These results suggested that facilitating effects of the ACC could be observed in the initial phase of agonist action in healthy participants, and ACC of shorter durations might be more effective. The increased dE/dt(max) suggested that increased neural activities might contribute to the antagonist conditioned facilitation of force development.

  6. Analysis of Tensile Stress-Strain and Work-Hardening Behavior in 9Cr-1Mo Ferritic Steel

    Choudhary, B. K.; Palaparti, D. P. Rao; Samuel, E. Isaac


    Detailed analysis on tensile true stress ( σ)-true plastic strain ( ɛ) and work-hardening behavior of 9Cr-1Mo steel have been performed in the framework of the Voce relationship and Kocks-Mecking approach for wide range of temperatures, 300 K to 873 K (27 °C to 600 °C) and strain rates (6.33 × 10-5 to 6.33 × 10-3 s-1). At all test conditions, σ- ɛ data were adequately described by the Voce equation. 9Cr-1Mo steel exhibited two-stage work-hardening behavior characterized by a rapid decrease in instantaneous work-hardening rate ( θ = dσ/ dɛ) with stress at low stresses (transient stage) followed by a gradual decrease in θ at high stresses (stage III). The variations of work-hardening parameters and θ- σ as a function of temperature and strain rate exhibited three distinct temperature regimes. Both work-hardening parameters and θ- σ displayed signatures of dynamic strain aging at intermediate temperatures and dominance of dynamic recovery at high temperatures. Excellent correlations have been obtained between work-hardening parameters evaluated using the Voce relationship and the respective tensile properties. A comparison of work-hardening parameters obtained using the Voce equation and Kocks-Mecking approach suggested an analogy between the two for the steel.

  7. Conditioning causes an increase in glucose transporter-4 levels in mononuclear cells in sled dogs.

    Schnurr, Theresia M; Reynolds, Arleigh J; Gustafson, Sally J; Duffy, Lawrence K; Dunlap, Kriya L


    This study was designed to investigate the effects of physical conditioning on the expression of the insulin sensitive glucose transporter-4 protein (GLUT4) on mononuclear cells and HOMA-IR levels in dogs and compared to results reported in human skeletal muscle and the skeletal muscle of rodent models. Blood was sampled from conditioned dogs (n = 8) and sedentary dogs (n = 8). The conditioned dogs were exercised four months prior the experiment and were following a uniform training protocol, whereas the sedentary dogs were not. GLUT4 expression in mononuclear cells and plasma insulin levels were measured using commercially available enzyme-linked immunosorbent assay (ELISA). Blood glucose levels were determined using blood plasma. HOMA-IR was calculated using plasma insulin and blood glucose levels using the linear approximation formula. Our results indicate that the state of conditioning had a significant effect on the GLUT4 expression at the surface of mononuclear cells. HOMA-IR was also affected by conditioning in dogs. GLUT4 levels in mononuclear cells of sled dogs were inversely correlated with the homeostasis model assessment of insulin sensitivity. This study demonstrates that conditioning increases GLUT4 levels in mononuclear cells of sled dogs as it has been previously reported in skeletal muscle. Our results support the potential of white blood cells as a proxy tissue for studying insulin signaling and may lead to development of a minimally invasive and direct marker of insulin resistance. This may be the first report of GLUT4 in mononuclear cells in response to exercise and measured with ELISA.

  8. Increased greenhouse-gas intensity of rice production under future atmospheric conditions

    van Groenigen, Kees Jan; van Kessel, Chris; Hungate, Bruce A.


    Increased atmospheric CO2 and rising temperatures are expected to affect rice yields and greenhouse-gas (GHG) emissions from rice paddies. This is important, because rice cultivation is one of the largest human-induced sources of the potent GHG methane (CH4) and rice is the world's second-most produced staple crop. The need for meeting a growing global food demand argues for assessing GHG emissions from croplands on the basis of yield rather than land area, such that efforts to reduce GHG emissions take into consideration the consequences for food production. However, it is unclear whether or how the GHG intensity (that is, yield-scaled GHG emissions) of cropping systems will be affected by future atmospheric conditions. Here we show, using meta-analysis, that increased atmospheric CO2 (ranging from 550 to 743ppmV) and warming (ranging from +0.8°C to +6°C) both increase the GHG intensity of rice cultivation. Increased atmospheric CO2 increased GHG intensity by 31.4%, because CH4 emissions are stimulated more than rice yields. Warming increased GHG intensity by 11.8% per 1°C, largely owing to a decrease in yield. This analysis suggests that rising CO2 and warming will approximately double the GHG intensity of rice production by the end of the twenty-first century, stressing the need for management practices that optimize rice production while reducing its GHG intensity as the climate continues to change.

  9. Role of work hardening characteristics of matrix alloys in the strengthening of metal matrix composites

    K T Kashyap; C Ramachandra; C Dutta; B Chatterji


    The strengthening of particulate reinforced metal–matrix composites is associated with a high dislocation density in the matrix due to the difference in coefficient of thermal expansion between the reinforcement and the matrix. While this is valid, the role of work hardening characteristics of the matrix alloys in strengthening of these composites is addressed in the present paper. It is found that commercial purity aluminium which has the lowest work hardening rate exhibits the highest strength increment. This effect is due to increased prismatic punching of dislocations. This relationship of decreasing work hardening rate associated with increasing prismatic punching of dislocations in the order 7075, 2014, 7010, 2024, 6061 and commercial purity aluminium leading to increased strength increments is noted.

  10. Effect of different growth conditions on biomass increase in kefir grains.

    Guzel-Seydim, Z; Kok-Tas, T; Ertekin-Filiz, B; Seydim, A C


    Kefir is a functional dairy product and the effects of kefir consumption on health have been well documented. Kefir grains have naturally high numbers of lactic acid bacteria and yeasts and are used in manufacturing kefir. The biomass of kefir grains slowly increases after successive fermentations. The effects of adding whey protein isolate, modified whey protein (MWP, fat replacer; Carbery Inc., Cork, Ireland), or inulin to milk and different atmospheric conditions (ambient or 6% CO(2)) during fermentation on the increase in biomass of kefir grains were investigated. Reconstituted milks (10% milk powder) enriched with whey protein isolate (2%), MWP (2%), and inulin (2%) were inoculated with kefir grains and fermented in ambient and 6% CO(2) incubators at 25°C until a final pH of 4.6 was reached. Biomass increments of kefir grains were determined weekly over 30 d. Lactic acid bacteria and yeast contents of kefir grains were also determined. The highest biomass increase (392%) was found in kefir grains grown in milk supplemented with whey protein isolate under ambient atmospheric conditions. Application of CO(2) did not provide a significant supporting effect on the biomass of kefir grains. Addition of MWP significantly accelerated the formation of kefir grain biomass (223%). The use of whey protein isolate, MWP, or inulin in milk did not cause any adverse effects on the microbial flora of kefir grains. Copyright © 2011 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  11. On the spectral hardening at ~> 300 keV in solar flares

    Li, Gang; Zank, Gary; Chen, Yao


    It has been noted for a long time that the spectra of observed continuum emissions in many solar flares are consistent with double power laws with a hardening at energies $\\sim > $ 300 keV. It is now largely believed that at least in electron-dominated events the hardening in photon spectrum reflects an intrinsic hardening in the source electron spectrum. In this paper, we point out that a power law spectrum of electron with a hardening at high energies can be explained by diffusive shock acceleration of electrons at a termination shock with a finite width. Our suggestion is based on an early analytical work by Drury et al., where the steady state transport equation at a shock with a tanh profile was solved for a $p$-independent diffusion coefficient. Numerical simulations with a $p$-dependent diffusion coefficient show hardenings in the accelerated electron spectrum which are comparable with observations. One necessary condition for our proposed scenario to work is that high energy electrons resonate with th...

  12. Multi-MGy Radiation Hardened Camera for Nuclear Facilities

    Girard, Sylvain; Boukenter, Aziz; Ouerdane, Youcef [Universite de Saint-Etienne, Lab. Hubert Curien, UMR-CNRS 5516, F-42000 Saint-Etienne (France); Goiffon, Vincent; Corbiere, Franck; Rolando, Sebastien; Molina, Romain; Estribeau, Magali; Avon, Barbara; Magnan, Pierre [ISAE, Universite de Toulouse, F-31055 Toulouse (France); Paillet, Philippe; Duhamel, Olivier; Gaillardin, Marc; Raine, Melanie [CEA, DAM, DIF, F-91297 Arpajon (France)


    There is an increasing interest in developing cameras for surveillance systems to monitor nuclear facilities or nuclear waste storages. Particularly, for today's and the next generation of nuclear facilities increasing safety requirements consecutive to Fukushima Daiichi's disaster have to be considered. For some applications, radiation tolerance needs to overcome doses in the MGy(SiO{sub 2}) range whereas the most tolerant commercial or prototypes products based on solid state image sensors withstand doses up to few kGy. The objective of this work is to present the radiation hardening strategy developed by our research groups to enhance the tolerance to ionizing radiations of the various subparts of these imaging systems by working simultaneously at the component and system design levels. Developing radiation-hardened camera implies to combine several radiation-hardening strategies. In our case, we decided not to use the simplest one, the shielding approach. This approach is efficient but limits the camera miniaturization and is not compatible with its future integration in remote-handling or robotic systems. Then, the hardening-by-component strategy appears mandatory to avoid the failure of one of the camera subparts at doses lower than the MGy. Concerning the image sensor itself, the used technology is a CMOS Image Sensor (CIS) designed by ISAE team with custom pixel designs used to mitigate the total ionizing dose (TID) effects that occur well below the MGy range in classical image sensors (e.g. Charge Coupled Devices (CCD), Charge Injection Devices (CID) and classical Active Pixel Sensors (APS)), such as the complete loss of functionality, the dark current increase and the gain drop. We'll present at the conference a comparative study between these radiation-hardened pixel radiation responses with respect to conventional ones, demonstrating the efficiency of the choices made. The targeted strategy to develop the complete radiation hard camera

  13. Cognitive work hardening: a return-to-work intervention for people with depression.

    Wisenthal, Adeena; Krupa, Terry


    Mental health claims in the workplace are rising, particularly those due to depression. Associated with this is an increase in disability costs for the employer and the disability insurer, but even more important is the human suffering that results. While treatments are available for the depression there is a gap in interventions that specifically target return-to-work preparation. This paper presents cognitive work hardening, a treatment intervention that can bridge this gap by addressing the unique functional issues inherent in depression with a view to increasing return-to-work success. Cognitive work hardening applies the proven principles of classical work hardening (which has typically been applied to people with physical injuries) to the mental health domain. This paper explains how the occupational therapy principle of occupation and the core competency, enablement, are utilized and applied in cognitive work hardening. Key skills of the occupational therapist are also discussed. In addition, the paper considers the relationship of cognitive work hardening to recovery and mental illness, and the role it plays among workplace-based return-to-work interventions in the current movement toward non-clinical return-to-work interventions.

  14. Effects of TEA·HCl hardening accelerator on the workability of cement-based materials

    Pan, Wenhao; Ding, Zhaoyang; Chen, Yanwen


    The aim of the test is to research the influence rules of TEA·HCl on the workability of cement paste and concrete. Based on the features of the new hardening accelerator, an experimental analysis system were established through different dosages of hardening accelerator, and the feasibility of such accelerator to satisfy the need of practical engineering was verified. The results show that adding of the hardening accelerator can accelerate the cement hydration, and what’s more, when the dosage was 0.04%, the setting time was the shortest while the initial setting time and final setting time were 130 min and 180 min, respectively. The initial fluidity of cement paste of adding accelerator was roughly equivalent compared with that of blank. After 30 min, fluidity loss would decrease with the dosage increasing, but fluidity may increase. The application of the hardening accelerator can make the early workability of concrete enhance, especially the slump loss of 30 min can improve more significantly. The bleeding rate of concrete significantly decreases after adding TEA·HCl. The conclusion is that the new hardening accelerator can meet the need of the workability of cement-based materials in the optimum dosage range.

  15. Muddy conditions reduce hygiene and lying time in dairy cattle and increase time spent on concrete.

    Chen, Jennifer M; Stull, Carolyn L; Ledgerwood, David N; Tucker, Cassandra B


    Dairy cattle spend less time lying and show signs of increased stress when housed in rainy and windy conditions, but no work has separated the effects of exposure to inclement weather from muddy conditions underfoot. Our objective was to evaluate the effects of muddy conditions alone on lying behavior, hygiene, and physiological responses. We housed pairs of pregnant, nonlactating dairy cattle (n = 12; 6 primigravid heifers, 6 multiparous cows) in enclosed pens with dirt floors and a concrete feed apron. Cattle were exposed to 3 levels of soil moisture: 90 (dry), 74 (muddy), or 67% (very muddy) dry matter for 5 d each in a replicated 3 × 3 Latin square design. Lying time was measured on all days with data loggers, and lying locations and postures were recorded on the final day of each treatment. Before and after each treatment, blood samples were collected, and the percentage of dirty surface area was measured on the udder, hind leg, and side of each animal. Cattle spent less time lying down in muddier conditions, especially in the first 24 h of exposure, when cows and heifers spent only 3.2 and 5.8 h, respectively, lying down in the muddiest treatment compared with 12.5 and 12.7 h on dry soil. When the soil was dry, cattle never chose to lie down on concrete, but in muddier conditions they spent a greater proportion of their lying time on concrete (mean ± SE: 56 ± 14 and 10 ± 8% in the very muddy and muddy treatments, respectively). The shift in lying location was more marked for heifers, and all 6 spent ≥87% of their lying time on concrete in the muddiest treatment. When cattle chose to lie down on wetter soil, they limited the surface area exposed to their surroundings by tucking their legs beneath their bodies (mean ± SE: 30 ± 11, 15 ± 4, and 5 ± 2% of lying observations in the very muddy, muddy, and dry treatments, respectively). Despite cattle spending less time on wetter soil, all 3 measured body parts became dirtier in muddier conditions (1.4-, 1

  16. Induction hardening treatment and simulation for a grey cast iron used in engine cylinder liners

    Castellanos-Leal, E. L.; Miranda, D. A.; Coy, A. E.; Barrero, J. G.; González, J. A.; Vesga Rueda, O. P.


    In this research, a technical study of induction hardening in a grey cast iron used in engine cylinder liners manufactured by LAVCO Ltda., a Colombian foundry company, was carried out. Metallurgical parameters such as austenitization temperature, cooling rate, and quenching severity were determined. These factors are exclusively dependent on chemical composition and initial microstructure of grey cast iron. Simulations of induction heating through finite elements method were performed and, the most appropriate experimental conditions to achieve the critical transformation temperature was evaluated to reach a proper surface hardening on the piece. Preliminary results revealed an excellent approximation between simulation and heating test performed with a full bridge inverter voltage adapted with local technology.

  17. Temperature Effects on the Tensile Properties of Precipitation-Hardened Al-Mg-Cu-Si Alloys

    J.B. Ferguson


    Full Text Available Because the mechanical performance of precipitation-hardened alloys can be significantly altered with temperature changes, understanding and predicting the effects of temperatures on various mechanical properties for these alloys are important. In the present work, an analytical model has been developed to predict the elastic modulus, the yield stress, the failure stress, and the failure strain taking into consideration the effect of temperatures for precipitation-hardenable Al-Mg-Cu-Si Alloys (Al-A319 alloys. In addition, other important mechanical properties of Al-A319 alloys including the strain hardening exponent, the strength coefficient, and the ductility parameter can be estimated using the current model. It is demonstrated that the prediction results based on the proposed model are in good agreement with those obtained experimentally in Al-A319 alloys in the as-cast condition and after W and T7 heat treatments.

  18. Densification and strain hardening of a metallic glass under tension at room temperature.

    Wang, Z T; Pan, J; Li, Y; Schuh, C A


    The deformation of metallic glasses involves two competing processes: a disordering process involving dilatation, free volume accumulation, and softening, and a relaxation process involving diffusional ordering and densification. For metallic glasses at room temperature and under uniaxial loading, disordering usually dominates, and the glass can fail catastrophically as the softening process runs away in a localized mode. Here we demonstrate conditions where the opposite, unexpected, situation occurs: the densifying process dominates, resulting in stable plastic deformation and work hardening at room temperature. We report densification and hardening during deformation in a Zr-based glass under multiaxial loading, in a notched tensile geometry. The effect is driven by stress-enhanced diffusional relaxation, and is attended by a reduction in exothermic heat and hardening signatures similar to those observed in the classical thermal relaxation of glasses. The result is significant, stable, plastic, extensional flow in metallic glasses, which suggest a possibility of designing tough glasses based on their flow properties.

  19. Intense two-cycle laser pulses induce time-dependent bond hardening in a polyatomic molecule.

    Dota, K; Garg, M; Tiwari, A K; Dharmadhikari, J A; Dharmadhikari, A K; Mathur, D


    A time-dependent bond-hardening process is discovered in a polyatomic molecule (tetramethyl silane, TMS) using few-cycle pulses of intense 800 nm light. In conventional mass spectrometry, symmetrical molecules such as TMS do not exhibit a prominent molecular ion (TMS(+)) as unimolecular dissociation into [Si(CH(3))(3)](+) proceeds very fast. Under a strong field and few-cycle conditions, this dissociation channel is defeated by time-dependent bond hardening: a field-induced potential well is created in the TMS(+) potential energy curve that effectively traps a wave packet. The time dependence of this bond-hardening process is verified using longer-duration (≥100 fs) pulses; the relatively slower falloff of optical field in such pulses allows the initially trapped wave packet to leak out, thereby rendering TMS(+) unstable once again.

  20. Stackable Radiation Hardened FRAM Project

    National Aeronautics and Space Administration — Satellite and space systems designers of long duration lunar and planetary missions continue to find it difficult to provide the ever increasing amount of memory...

  1. Micromilling of hardened tool steels

    Li, P.


    Miniaturized parts are increasingly demanded in different fields like medical, transportation, environmental, and communication industries. In order to manufacture these parts in an economical way, mass replication methods, such as micro injection molding, have to be applied. Currently, Electro Disc

  2. Meal ingestion markedly increases liver stiffness suggesting the need for liver stiffness determination in fasting conditions.

    Alvarez, Daniel; Orozco, Federico; Mella, José María; Anders, Maria; Antinucci, Florencia; Mastai, Ricardo


    The introduction of noninvasive liver stiffness (LS) determination has heralded a new stage in the diagnosis and treatment of liver fibrosis. We evaluated the effect of food intake on LS in patients with different degrees of liver disease. We evaluated 24 patients (F≤1, n=11 and F> 1, n=13). LS (Fibroscan®) and portal blood flow (PBF) (Doppler ultrasound) were studied before and 30min after ingestion of a standard liquid meal. Food intake increased PBF (51±10%, p1). Hemodynamic and LS values returned to baseline pre-meal levels within 2hours. LS increases markedly after ingestion of a standard meal, irrespective of the degree of fibrosis. Our results strongly suggest that LS should be measured in fasting conditions. Copyright © 2015 Elsevier España, S.L.U. and AEEH y AEG. All rights reserved.

  3. Increased Land Use by Chukchi Sea Polar Bears in Relation to Changing Sea Ice Conditions.

    Karyn D Rode

    Full Text Available Recent observations suggest that polar bears (Ursus maritimus are increasingly using land habitats in some parts of their range, where they have minimal access to their preferred prey, likely in response to loss of their sea ice habitat associated with climatic warming. We used location data from female polar bears fit with satellite radio collars to compare land use patterns in the Chukchi Sea between two periods (1986-1995 and 2008-2013 when substantial summer sea-ice loss occurred. In both time periods, polar bears predominantly occupied sea-ice, although land was used during the summer sea-ice retreat and during the winter for maternal denning. However, the proportion of bears on land for > 7 days between August and October increased between the two periods from 20.0% to 38.9%, and the average duration on land increased by 30 days. The majority of bears that used land in the summer and for denning came to Wrangel and Herald Islands (Russia, highlighting the importance of these northernmost land habitats to Chukchi Sea polar bears. Where bears summered and denned, and how long they spent there, was related to the timing and duration of sea ice retreat. Our results are consistent with other studies supporting increased land use as a common response of polar bears to sea-ice loss. Implications of increased land use for Chukchi Sea polar bears are unclear, because a recent study observed no change in body condition or reproductive indices between the two periods considered here. This result suggests that the ecology of this region may provide a degree of resilience to sea ice loss. However, projections of continued sea ice loss suggest that polar bears in the Chukchi Sea and other parts of the Arctic may increasingly use land habitats in the future, which has the potential to increase nutritional stress and human-polar bear interactions.

  4. After Medicaid Expansion In Kentucky, Use Of Hospital Emergency Departments For Dental Conditions Increased.

    Chalmers, Natalia; Grover, Jane; Compton, Rob


    Access to oral health care is a critical need for the adult Medicaid population. Following the 2014 expansion of Medicaid eligibility in Kentucky, millions of adults became eligible to receive dental benefits. We examined the impact of the expansion on adult Medicaid enrollees' use of hospital emergency departments (EDs) for conditions related to dental or oral health in the period 2010-14. Based on our analysis of data for Kentucky from the State Emergency Department Databases, we found that the rate of discharges for these conditions from the ED increased significantly, from 1,833 per 100,000 population in 2013 to 5,635 in 2014. Adults covered by Medicaid who used the ED for treatment of oral health conditions in 2014 had high levels of chronic comorbidities and were more likely to be male and nonwhite than those in earlier years. To avoid costly and inappropriate use of the ED, states considering adding an adult Medicaid dental benefit should consider also making changes to assist beneficiaries in obtaining access to the dental health care delivery system.

  5. Inoculant of Arbuscular Mycorrhizal Fungi (Rhizophagus clarus) Increase Yield of Soybean and Cotton under Field Conditions

    Cely, Martha V. T.; de Oliveira, Admilton G.; de Freitas, Vanessa F.; de Luca, Marcelo B.; Barazetti, André R.; dos Santos, Igor M. O.; Gionco, Barbara; Garcia, Guilherme V.; Prete, Cássio E. C.; Andrade, Galdino


    Nutrient availability is an important factor in crop production, and regular addition of chemical fertilizers is the most common practice to improve yield in agrosystems for intensive crop production. The use of some groups of microorganisms that have specific activity providing nutrients to plants is a good alternative, and arbuscular mycorrhizal fungi (AMF) enhance plant nutrition by providing especially phosphorus, improving plant growth and increasing crop production. Unfortunately, the use of AMF as an inoculant on a large scale is not yet widely used, because of several limitations in obtaining a large amount of inoculum due to several factors, such as low growth, the few species of AMF domesticated under in vitro conditions, and high competition with native AMF. The objective of this work was to test the infectivity of a Rhizophagus clarus inoculum and its effectiveness as an alternative for nutrient supply in soybean (Glycine max L.) and cotton (Gossypium hirsutum L.) when compared with conventional chemical fertilization under field conditions. The experiments were carried out in a completely randomized block design with five treatments: Fertilizer, AMF, AMF with Fertilizer, AMF with 1/2 Fertilizer, and the Control with non-inoculated and non-fertilized plants. The parameters evaluated were AMF root colonization and effect of inoculation on plant growth, nutrient absorption and yield. The results showed that AMF inoculation increased around 20 % of root colonization in both soybean and cotton; nutrients analyses in vegetal tissues showed increase of P and nitrogen content in inoculated plants, these results reflect in a higher yield. Our results showed that, AMF inoculation increase the effectiveness of fertilizer application in soybean and reduce the fertilizer dosage in cotton. PMID:27303367

  6. Informed conditioning on clinical covariates increases power in case-control association studies.

    Zaitlen, Noah; Lindström, Sara; Pasaniuc, Bogdan; Cornelis, Marilyn; Genovese, Giulio; Pollack, Samuela; Barton, Anne; Bickeböller, Heike; Bowden, Donald W; Eyre, Steve; Freedman, Barry I; Friedman, David J; Field, John K; Groop, Leif; Haugen, Aage; Heinrich, Joachim; Henderson, Brian E; Hicks, Pamela J; Hocking, Lynne J; Kolonel, Laurence N; Landi, Maria Teresa; Langefeld, Carl D; Le Marchand, Loic; Meister, Michael; Morgan, Ann W; Raji, Olaide Y; Risch, Angela; Rosenberger, Albert; Scherf, David; Steer, Sophia; Walshaw, Martin; Waters, Kevin M; Wilson, Anthony G; Wordsworth, Paul; Zienolddiny, Shanbeh; Tchetgen, Eric Tchetgen; Haiman, Christopher; Hunter, David J; Plenge, Robert M; Worthington, Jane; Christiani, David C; Schaumberg, Debra A; Chasman, Daniel I; Altshuler, David; Voight, Benjamin; Kraft, Peter; Patterson, Nick; Price, Alkes L


    Genetic case-control association studies often include data on clinical covariates, such as body mass index (BMI), smoking status, or age, that may modify the underlying genetic risk of case or control samples. For example, in type 2 diabetes, odds ratios for established variants estimated from low-BMI cases are larger than those estimated from high-BMI cases. An unanswered question is how to use this information to maximize statistical power in case-control studies that ascertain individuals on the basis of phenotype (case-control ascertainment) or phenotype and clinical covariates (case-control-covariate ascertainment). While current approaches improve power in studies with random ascertainment, they often lose power under case-control ascertainment and fail to capture available power increases under case-control-covariate ascertainment. We show that an informed conditioning approach, based on the liability threshold model with parameters informed by external epidemiological information, fully accounts for disease prevalence and non-random ascertainment of phenotype as well as covariates and provides a substantial increase in power while maintaining a properly controlled false-positive rate. Our method outperforms standard case-control association tests with or without covariates, tests of gene x covariate interaction, and previously proposed tests for dealing with covariates in ascertained data, with especially large improvements in the case of case-control-covariate ascertainment. We investigate empirical case-control studies of type 2 diabetes, prostate cancer, lung cancer, breast cancer, rheumatoid arthritis, age-related macular degeneration, and end-stage kidney disease over a total of 89,726 samples. In these datasets, informed conditioning outperforms logistic regression for 115 of the 157 known associated variants investigated (P-value = 1 × 10(-9)). The improvement varied across diseases with a 16% median increase in χ(2) test statistics and a

  7. Effect of Sc on Precipitation Hardening of AlSi6Mg Alloy


    The effect of Sc on precipitation hardening of AlSi6Mg was studied. Zr was previously reported that it increased the effectiveness of Sc in wrought aluminum in many areas so Zr was also used together with Sc in this study.Different levels of Sc and Zr additions were added to AlSi6Mg before casting in the permanent mold. The samples were precipitation hardened at different aging temperatures and for various aging time before testing for tensile strength and hardness. It was found that Sc addition into Al6SiMg can change its response to age hardening. Additions of Sc and Sc with Zr increased both yield strength and hardness for both aging temperatures. In addition, Sc was found to modify eutectic Si to obtain fibrous morphology. This effect of Sc on eutectic silicon modification has never been reported before.

  8. Secondary Hardening, Austenite Grain Coarsening and Surface Decarburization Phenomenon in Nb-Bearing Spring Steel


    The secondary hardening, the austenite grain coarsening and the surface decarburization phenomenon of Nb-bearing spring steel were investigated, and the effects of niobium on tempered microstructure was studied using scanning electron microscope. The results show that the micro-addition of niobium increases the tempering resistance and produces secondary hardening. The effect of niobium on the size and distribution of cementite particles is one of the primary reasons to increase the hardness after tempering. The grain-coarsening temperature of the spring steel is raised 150 ~C due to Nb-addition. Furthermore, both the secondary hardening and the austenite grain coarsening phenomenon congruously demonstrate niobium begins observably dissolving above 1 100 ℃ in the spring steel. Be- sides, niobium microalloying is an effective and economy means to decrease the decarburization sensitivity of the spring steels.

  9. Embrittlement of irradiated F82H in the absence of irradiation hardening

    Klueh, R.L. [Oak Ridge National Laboratory, Oak Ridge, Tennessee (United States)], E-mail:; Shiba, K. [Japan Atomic Energy Agency, Toki-Mura, Ibaraki (Japan); Sokolov, M.A. [Oak Ridge National Laboratory, Oak Ridge, Tennessee (United States)


    Neutron irradiation of 7-12% Cr ferritic/martensitic steels below 425-450 deg. C produces microstructural defects and precipitation that cause an increase in yield stress. This irradiation hardening causes embrittlement, which is observed in a Charpy impact or fracture toughness test as an increase in the ductile-brittle transition temperature. Based on observations that show little change in strength in steels irradiated above 425-450 deg. C, the general conclusion has been that no embrittlement occurs above these temperatures. In a recent study of F82H steel, significant embrittlement was observed after irradiation at 500 deg. C, but no hardening occurred. This embrittlement is apparently due to irradiation-accelerated Laves-phase precipitation. Observations of the embrittlement of F82H in the absence of irradiation hardening have been examined and analyzed with thermal-aging studies and computational thermodynamics calculations to illuminate and understand the embrittlement during irradiation.

  10. Hardening of the surface layers of commercial pure titanium VT1-0 under combined treatment

    Bashchenko, Lyudmila P.; Gromov, Viktor E.; Budovskikh, Evgenii A.; Ivanov, Yurii F.; Soskova, Nina A.


    The treatment of VT1-0 titanium samples was carried out by concentrated energy fluxes. The combined treatment included surface carburizing with the joint use of powder samples of compounds with high physical and mechanical properties (namely, titanium diboride TiB2, silicon carbide SiC and zirconium oxide ZrO2) and subsequent electron beam treatment of surface layers formed in electroexplosive treatment. The combined treatment of surface layers resulted in the multifold increase in microhardness, which reduces depending on the depth of hardening zone. After electron-beam treatment, the depth of hardening zone is increased. During electron-beam treatment, the two-layer hardening zone forms.

  11. Hardening of the surface layers of commercial pure titanium VT1-0 under combined treatment

    Bashchenko, Lyudmila P., E-mail:; Gromov, Viktor E., E-mail:; Budovskikh, Evgenii A., E-mail:; Soskova, Nina A., E-mail: [Siberian State Industrial University, Novokuznetsk, 654007 (Russian Federation); Ivanov, Yurii F., E-mail: [Institute of High Current Electronics SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation)


    The treatment of VT1-0 titanium samples was carried out by concentrated energy fluxes. The combined treatment included surface carburizing with the joint use of powder samples of compounds with high physical and mechanical properties (namely, titanium diboride TiB{sub 2}, silicon carbide SiC and zirconium oxide ZrO{sub 2}) and subsequent electron beam treatment of surface layers formed in electroexplosive treatment. The combined treatment of surface layers resulted in the multifold increase in microhardness, which reduces depending on the depth of hardening zone. After electron-beam treatment, the depth of hardening zone is increased. During electron-beam treatment, the two-layer hardening zone forms.

  12. Characterization of Radiation Hardened Bipolar Linear Devices for High Total Dose Missions

    McClure, Steven S.; Harris, Richard D.; Rax, Bernard G.; Thorbourn, Dennis O.


    Radiation hardened linear devices are characterized for performance in combined total dose and displacement damage environments for a mission scenario with a high radiation level. Performance at low and high dose rate for both biased and unbiased conditions is compared and the impact to hardness assurance methodology is discussed.

  13. Elevated Atmospheric CO2 Affects Ectomycorrhizal Species Abundance and Increases Sporocarp Production under Field Conditions

    Douglas L. Godbold


    Full Text Available Anthropogenic activities during the last century have increased levels of atmospheric CO2. Forest net primary productivity increases in response to elevated CO2, altering the quantity and quality of carbon supplied to the rhizosphere. Ectomycorrhizal fungi form obligate symbiotic associations with the fine roots of trees that mediate improved scavenging for nutrients in exchange for a carbohydrate supply. Understanding how the community structure of ectomycorrhizal fungi is altered by climate change is important to further our understanding of ecosystem function. Betula pendula and Fagus sylvatica were grown in an elevated CO2 atmosphere delivered using free air carbon dioxide enrichment (FACE under field conditions in the U.K., and Picea abies was grown under elevated CO2 in glass domes in the Czech Republic. We used morphotyping and sequencing of the internal transcribed spacer region of the fungal ribosomal operon to study ectomycorrhizal community structure. Under FACE, un-colonised roots tips increased in abundance for Fagus sylvatica, and during 2006, sporocarp biomass of Peziza badia significantly increased. In domes, ectomycorrhizal community composition shifted from short-distance and smooth medium-distance to contact exploration types. Supply and competition for carbon belowground can influence ectomycorrhizal community structure with the potential to alter ecosystem function.

  14. Origin of the Cosmic Ray Spectral Hardening

    Tomassetti, N


    Recent data from ATIC, CREAM and PAMELA indicate that the cosmic ray energy spectra of protons and nuclei exhibit a remarkable hardening at energies above 100 GeV per nucleon. We propose that the hardening is an interstellar propagation effect that originates from a spatial change of the cosmic ray transport properties in different regions of the Galaxy. The key hypothesis is that the diffusion coefficient is not separable into energy and space variables as usually assumed. Under this scenario, we can reproduce well the observational data. Our model has several implications for the cosmic ray acceleration/propagation physics and can be tested by ongoing experiments such as AMS or Fermi/LAT.

  15. Construction procedures using self hardening fly ash

    Thornton, S. I.; Parker, D. G.


    Fly ash produced in Arkansas from burning Wyoming low sulfur coal is self-hardening and can be effective as a soil stabilizing agent for clays and sands. The strength of soil-self hardening fly ash develops rapidly when compacted immediately after mixing. Seven day unconfined compressive strengths up to 1800 psi were obtained from 20% fly ash and 80% sand mixtures. A time delay between mixing the fly ash with the soil and compaction of the mixture reduced the strength. With two hours delay, over a third of the strength was lost and with four hours delay, the loss was over half. Gypsum and some commercial concrete retarders were effective in reducing the detrimental effect of delayed compaction. Adequate mixing of the soil and fly ash and rapid compaction of the mixtures were found to be important parameters in field construction of stabilized bases.

  16. Radiation-hardened transistor and integrated circuit

    Ma, Kwok K.


    A composite transistor is disclosed for use in radiation hardening a CMOS IC formed on an SOI or bulk semiconductor substrate. The composite transistor has a circuit transistor and a blocking transistor connected in series with a common gate connection. A body terminal of the blocking transistor is connected only to a source terminal thereof, and to no other connection point. The blocking transistor acts to prevent a single-event transient (SET) occurring in the circuit transistor from being coupled outside the composite transistor. Similarly, when a SET occurs in the blocking transistor, the circuit transistor prevents the SET from being coupled outside the composite transistor. N-type and P-type composite transistors can be used for each and every transistor in the CMOS IC to radiation harden the IC, and can be used to form inverters and transmission gates which are the building blocks of CMOS ICs.


    O. V. Dvornikov


    Full Text Available Problems of specialized analog integrated circuit design for sensor equipments are considered. It is offered to produce of radiation hardened analog IC on structured chips for economic efficiency at small production volume. The approach to analog IC design is described, including recommendations for choice of: types and quantities of structured chip analogue components; active and passive components; schematic decisions of analogue components with programmed parameters and small sensitivity to radiation. 

  18. "Danger" conditions increase sulfamethoxazole-protein adduct formation in human antigen-presenting cells.

    Lavergne, S N; Wang, H; Callan, H E; Park, B K; Naisbitt, D J


    Antigen-presenting cells (APC) are thought to play an important role in the pathogenesis of drug-induced immune reactions. Various pathological factors can activate APC and therefore influence the immune equilibrium. It is interesting that several diseases have been associated with an increased rate of drug allergy. The aim of this project was to evaluate the impact of such "danger signals" on sulfamethoxazole (SMX) metabolism in human APC (peripheral blood mononuclear cells, Epstein-Barr virus-modified B lymphocytes, monocyte-derived dendritic cells, and two cell lines). APC were incubated with SMX (100 microM-2 mM; 5 min-24 h), in the presence of pathological factors: bacterial endotoxins (lipopolysaccharide and staphylococcal enterotoxin B), flu viral proteins, cytokines [interleukin (IL)-1beta, IL-6, IL-10; tumor necrosis factor-alpha; interferon-gamma; and transforming growth factor-beta], inflammatory molecules (prostaglandin E2, human serum complement, and activated protein C), oxidants (buthionine sulfoximine and H(2)O(2)), and hyperthermia (37.5-39.5 degrees C). Adduct formation was evaluated by enzyme-linked immunosorbent assay and confocal microscopy. SMX-protein adduct formation was time- and concentration-dependent for each cell type tested, in both physiological and danger conditions. A danger environment significantly increased the formation of SMX-protein adducts and significantly shortened the delay for their detection. An additive effect was observed with a combination of danger signals. Dimedone (chemical selectively binding cysteine sulfenic acid) and antioxidants decreased both baseline and danger-enhanced SMX-adduct formation. Various enzyme inhibitors were associated with a significant decrease in SMX-adduct levels, with a pattern varying depending on the cell type and the culture conditions. These results illustrate that danger signals enhance the formation of intracellular SMX-protein adducts in human APC. These findings might be relevant

  19. Theobromine increases NAD⁺/Sirt-1 activity and protects the kidney under diabetic conditions.

    Papadimitriou, Alexandros; Silva, Kamila C; Peixoto, Elisa B M I; Borges, Cynthia M; Lopes de Faria, Jacqueline M; Lopes de Faria, José B


    Reduction in sirtuin 1 (Sirt-1) is associated with extracellular matrix (ECM) accumulation in the diabetic kidney. Theobromine may reduce kidney ECM accumulation in diabetic rats. In the current study, we aimed to unravel, under diabetic conditions, the mechanism of kidney ECM accumulation induced by a reduction in Sirt-1 and the effect of theobromine in these events. In vitro, we used immortalized human mesangial cells (iHMCs) exposed to high glucose (HG; 30 mM), with or without small interfering RNA for NOX4 and Sirt-1. In vivo, spontaneously hypertensive rats (SHR) were rendered diabetic by means of streptozotocin and studied after 12 wk. The effects of treatment with theobromine were investigated under both conditions. HG leads to a decrease in Sirt-1 activity and NAD(+) levels in iHMCs. Sirt-1 activity could be reestablished by treatment with NAD(+), silencing NOX4, and poly (ADP-ribose) polymerase-1 (PARP-1) blockade, or with theobromine. HG also leads to a low AMP/ATP ratio, acetylation of SMAD3, and increased collagen IV, which is prevented by theobromine. Sirt-1 or AMPK blockade abolished these effects of theobromine. In diabetic SHR, theobromine prevented increases in albuminuria and kidney collagen IV, reduced AMPK, elevated NADPH oxidase activity and PARP-1, and reduced NAD(+) levels and Sirt-1 activity. These results suggest that in diabetes mellitus, Sirt-1 activity is reduced by PARP-1 activation and NAD(+) depletion due to low AMPK, which increases NOX4 expression, leading to ECM accumulation mediated by transforming growth factor (TGF)-β1 signaling. It is suggested that Sirt-1 activation by theobromine may have therapeutic potential for diabetic nephropathy.

  20. Microstructure, Tensile Properties and Work Hardening Behavior of GTA-Welded Dual-Phase Steels

    Ashrafi, H.; Shamanian, M.; Emadi, R.; Saeidi, N.


    In the present study, microstructure, tensile properties and work hardening behavior of a DP700 steel after gas tungsten arc welding were investigated. Formation of bainite in the fusion zone resulted in a hardness increase compared to that for the base metal (BM), whereas tempering of the pre-existing martensite in the subcritical heat-affected zone (HAZ) led to softening. The GTA-welded joint exhibited a continuous yielding behavior and a yield strength close to that for the BM, while its ultimate tensile strength and total elongation were lower than those for the BM owing to the formation of soft zone in the HAZ. A joint efficiency of about 81% was obtained for the GTA-welded joint, and it failed in the softened HAZ. Analysis of work hardening based on the Kocks-Mecking approach showed one stage of hardening behavior corresponding to the stage III for both the DP700 BM and welded sample. It was also revealed that the DP700 BM has larger values of work hardening exponent and magnitude of work hardening compared with the welded sample. Analysis of fractured surfaces showed that the dominant fracture mode for both the DP700 BM and welded joint was ductile.

  1. Beam hardening correction algorithm in microtomography images

    Sales, Erika S.; Lima, Inaya C.B.; Lopes, Ricardo T., E-mail: esales@con.ufrj.b, E-mail: ricardo@lin.ufrj.b [Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Lab. de Instrumentacao Nuclear; Assis, Joaquim T. de, E-mail: joaquim@iprj.uerj.b [Universidade do Estado do Rio de Janeiro (UERJ), Nova Friburgo, RJ (Brazil). Inst. Politecnico. Dept. de Engenharia Mecanica


    Quantification of mineral density of bone samples is directly related to the attenuation coefficient of bone. The X-rays used in microtomography images are polychromatic and have a moderately broad spectrum of energy, which makes the low-energy X-rays passing through a sample to be absorbed, causing a decrease in the attenuation coefficient and possibly artifacts. This decrease in the attenuation coefficient is due to a process called beam hardening. In this work the beam hardening of microtomography images of vertebrae of Wistar rats subjected to a study of hyperthyroidism was corrected by the method of linearization of the projections. It was discretized using a spectrum in energy, also called the spectrum of Herman. The results without correction for beam hardening showed significant differences in bone volume, which could lead to a possible diagnosis of osteoporosis. But the data with correction showed a decrease in bone volume, but this decrease was not significant in a confidence interval of 95%. (author)

  2. Future atmospheric conditions increase the greenhouse gas intensity of rice production

    Van Groenigen, K.; Van Kessel, C.; Hungate, B. A.


    Elevated levels of atmospheric CO2 and rising temperatures are both expected to alter rice yields and greenhouse gas (GHG) emissions from rice paddies. This is important, because rice cultivation is one of the largest anthropogenic sources of the potent GHG methane (CH4) and rice is the world's second-most produced staple crop. Because global food demand is growing, it makes sense to assess GHG emissions from croplands on the basis of yield rather than land area, so that efforts to reduce GHG emissions occur with taking into consideration the effects on food production. However, it is unclear whether or how the GHG intensity (that is, yield-scaled GHG emissions) of cropping systems will be affected by future atmospheric conditions. Using meta-analysis, we show that elevated atmospheric CO2 (ranging from 550 to 743 ppmV) and warming (ranging from +0.8°C to +6°C) both increase the GHG intensity of rice cultivation. Elevated atmospheric CO2 increased GHG intensity by 31.4%, because CH4 emissions are stimulated more than rice yields. Warming increased GHG intensity by 11.8% per 1°C, largely due to a decrease in yield. Our findings underscore the need for mitigation and adaptation efforts to secure global food supply while at the same time keeping GHG emissions in check.

  3. Radiation-hardened microwave system

    Smith, S.F.; Bible, D.W.; Crutcher, R.I.; Moore, J.A.; Nowlin, C.H.; Vandermolen, R.I.


    In order to develop a wireless communication system to meet the stringent requirements for a nuclear hot cell and similar environments, including control of advanced servomanipulators, a microwave signal transmission system development program was established to produce a demonstration prototype for the Consolidated Fuel Reprocessing Program at the Oak Ridge National Laboratory. Proof-of-principle tests in a partially metal lined enclosure at ORNL successfully demonstrated the feasibility of directed microwave signal transmission techniques for remote systems applications. The potential for much more severe RF multipath propagation conditions in fully metal lined cells led to a programmatic decision to conduct additional testing in more typical hot-cell environments at other sites. Again, the test results were excellent. Based on the designs of the earlier systems, an advanced MSTS configuration was subsequently developed that, in highly reflective environments, will support both high-performance video channels and high band-rate digital data links at total gamma dose tolerance levels exceeding 10{sup 7} rads and at elevated ambient temperatures. 3 refs., 4 figs.

  4. A theoretical model of virtual water trade under increasing water scarcity conditions

    de Vos, Lotte; Pande, Saket


    This paper proposes a virtual water trade model to obtain a better understanding of how hydro-climatic change affects societies through changes in virtual water trade. In previous studies it has been shown that global trade patterns can be influenced by water scarcity and vice-versa. The extent to which this relationship holds is still a topic under discussion. With the model introduced in this paper, the dynamics behind these trade patterns are further explored. First, a model is constructed of a society suffering from an increase in water scarcity. This model is shown to be capable of replicating patterns of technological, population, production and consumption per capita changes. In order to incorporate the effects of globalization and trade, the model has been extended to a toy model of virtual water trade between two societies. The two societies are represented by overlapping generations models. The individuals of each generation provide the labour needed for the production of the composite goods. In addition to this labour, water and technology are also incorporated as factors of production. There are two goods being produced; one is labour intensive and the other water intensive. Trade emerges from the principle of comparative advantage, with differences in labour-abundance and water resources availability between the two societies. Using this model of two societies interconnected by trade, it is examined how trade of water-intensive commodities alters under changing scarcity conditions. In particular we explore the conditions under which trade emerges, and to what extent. Furthermore, we present the conditions for the sustainable development within these two societies.

  5. Warming Ocean Conditions Relate to Increased Trophic Requirements of Threatened and Endangered Salmon.

    Daly, Elizabeth A; Brodeur, Richard D


    The trophic habits, size and condition of yearling Chinook salmon (Oncorhynchus tshawytscha) caught early in their marine residence were examined during 19 survey years (1981-1985; 1998-2011). Juvenile salmon consumed distinct highly piscivorous diets in cold and warm ocean regimes with major differences between ocean regimes driven by changes in consumption of juvenile rockfishes, followed by several other fish prey, adult euphausiids and decapod larvae. Notable, Chinook salmon consumed 30% more food in the warm versus cold ocean regime in both May and June. Additionally, there were about 30% fewer empty stomachs in the warm ocean regime in May, and 10% fewer in warm June periods. The total prey energy density consumed during the warmer ocean regime was also significantly higher than in cold. Chinook salmon had lower condition factor and were smaller in fork length during the warm ocean regime, and were longer and heavier for their size during the cold ocean regime. The significant increase in foraging during the warm ocean regime occurred concurrently with lower available prey biomass. Adult return rates of juvenile Chinook salmon that entered the ocean during a warm ocean regime were lower. Notably, our long term data set contradicts the long held assertion that juvenile salmon eat less in a warm ocean regime when low growth and survival is observed, and when available prey are reduced. Comparing diet changes between decades under variable ocean conditions may assist us in understanding the effects of projected warming ocean regimes on juvenile Chinook salmon and their survival in the ocean environment. Bioenergetically, the salmon appear to require more food resources during warm ocean regimes.

  6. Shaping the Organizational Culture in Conditions of Increasing the Competitiveness of Enterprises

    Joanna Rębisz


    Full Text Available The organizational culture is one of key factors which can influence the organizational success in building the long-lasting domination of an enterprise. The article is an attempt to introduce and at the same time to present the understanding of the culture in terms of expected bearings which can explain why organizational individuals (or entire organizations promote only the behaviors which are in accordance with the value and the mission of the enterprises. The author draws attention to the level of expectations and behavior, which is usually the result of team work. A lot of attention has also been paid to the phenomenon of crossing of two relations: organizational culture with the function of leadership. The author has also discussed the role of a manager as a means of shaping and supporting an organization culture in conditions of increasing competition.

  7. Supplementary artificial light to increase egg production of geese under natural lighting conditions.

    Wang, Chin-Meng; Chen, Lih-Ren; Lee, Shuen-Rong; Jea, Yu-Shine; Kao, Jung-Yie


    A new supplementary lighting program was designed to increase the egg production of geese under natural light conditions. The objective of this study was to evaluate the effects of the supplementary lighting program on egg production of White Roman geese in an open housing system at the Tropic of Cancer. Forty mature White Roman geese were randomly allocated into two groups (male:female=1:4). The supplementary lighting program with a total daily photoperiod of between 12.0 h and 13.5 h was initiated on 1 November and withdrawn from the experimental group on 30 January. In contrast, the geese in the control group were kept under natural lighting conditions throughout this study. The results showed that the laying peak of the experimental group occurred earlier than normal in the reproductive season and the geese continued laying throughout the breeding season. The geese in the experimental group had 47.6 eggs/goose which was significantly (PTropic of Cancer.

  8. Federally Qualified Health Center Clinicians And Staff Increasingly Dissatisfied With Workplace Conditions.

    Friedberg, Mark W; Reid, Rachel O; Timbie, Justin W; Setodji, Claude; Kofner, Aaron; Weidmer, Beverly; Kahn, Katherine


    Better working conditions for clinicians and staff could help primary care practices implement delivery system innovations and help sustain the US primary care workforce. Using longitudinal surveys, we assessed the experience of clinicians and staff in 296 clinical sites that participated in the Centers for Medicare and Medicaid Services (CMS) Federally Qualified Health Center (FQHC) Advanced Primary Care Practice Demonstration. Participating FQHCs were expected to achieve, within three years, patient-centered medical home recognition at level 3-the highest level possible. During 2013-14, clinicians and staff in these FQHCs reported statistically significant declines in multiple measures of professional satisfaction, work environment, and practice culture. There were no significant improvements on any surveyed measure. These findings suggest that working conditions in FQHCs have deteriorated recently. Whether findings would be similar in other primary care practices is unknown. Although we did not identify the causes of these declines, possible stressors include the adoption of health information technology, practice transformation, and increased demand for services. Project HOPE—The People-to-People Health Foundation, Inc.

  9. Evaluation of the effect of CaCl2 and alginate concentrations and hardening time on the characteristics of Lactobacillus acidophilus loaded alginate beads using response surface analysis

    Lotfipour, Farzaneh; Mirzaeei, Shahla; Maghsoodi, Maryam


    Purpose: This article describes preparation and characterization of beads of alginate containing probiotic bacteria of Lactobacillus acidophilus DMSZ20079. Methods: Fourteen formulations using different alginate (ALG) and CaCl2 concentrations as well as hardening times were prepared using extrusion technique. The prepared beads were characterized in terms of size, morphology, encapsulation efficiency and bacterial viabilities in acid (pH 1.8, 2 hours) condition. Results: The results showed that spherical beads with narrow size distribution ranging from 1.32±0.04 to 1.70±0.07 mm were achieved with encapsulation efficiency higher than 98%. Surface response analysis revealed that alginate concentration was the important factor for the size, shape and encapsulation efficiency of prepared beads. Furthermore, survived bacteria after acid exposure in all prepared beads (63-83%) were significantly higher than those of untreated cells (39%) and enhanced by increasing alginate concentration. Surface response analysis revealed that the effect of all three factors of alginate and CaCl2 concentrations as well as hardening times were significant in acid viability, however alginate concentration played the most important role according to its regression coefficient. Conclusion: Among alginate and CaCl2 concentrations as well as hardening times, alginate concentration was the most variable in the characteristics of Alginate beads. PMID:24312773

  10. Benzodiazepines increase the reward effects of buprenorphine in a conditioned place preference test in the mouse.

    Ma, Lin-Lin; Freret, Thomas; Lange, Mathilde; Bourgine, Joanna; Coquerel, Antoine; Lelong-Boulouard, Véronique


    Buprenorphine (BPN) is widely used as a substitution treatment for opioid addiction. Some cases of abuse and misuse, especially associated with various benzodiazepines (BZDs), have been described, and a previous study has shown that BZDs increase the sedative effect of BPN and decrease its anxiogenic properties. To investigate the reward effect that may lead to the abusive combination of BPN and BZD, we studied the influence of different doses of three BZDs extensively used with BPN by drug addicts on conditioned place preference behavior in mice. BPN (0.3, 1, 3 mg/kg) was injected subcutaneously into male mice alone or in combination with a BZD administered intraperitoneally: dipotassium clorazepate (CRZ; 1, 4, 16 mg/kg), diazepam (DAZ; 0.5, 1, 5 mg/kg), or bromazepam (BMZ; 0.5, 1, 3 mg/kg). Amphetamine (8 mg/kg) was used as a reference drug. Reward effects of BPN alone or in combination were measured in a conditioned place preference paradigm using an unbiased procedure. Our results showed that groups treated with BPN associated with different doses of diazepam and clorazepate, but not bromazepam, spent significantly more time in the drug-paired compartment compared to the group treated with BPN alone. Our study shows that joint consumption of diazepam and clorazepate, but not bromazepam, can increase the reward properties of BPN alone in mice. These results could help to explain the use of this type of drug combination in the drug addict population. © 2014 Société Française de Pharmacologie et de Thérapeutique.

  11. Informed Conditioning on Clinical Covariates Increases Power in Case-Control Association Studies

    Zaitlen, Noah; Lindström, Sara; Pasaniuc, Bogdan; Cornelis, Marilyn; Genovese, Giulio; Pollack, Samuela; Barton, Anne; Bickeböller, Heike; Bowden, Donald W.; Eyre, Steve; Freedman, Barry I.; Friedman, David J.; Field, John K.; Groop, Leif; Haugen, Aage; Heinrich, Joachim; Henderson, Brian E.; Hicks, Pamela J.; Hocking, Lynne J.; Kolonel, Laurence N.; Landi, Maria Teresa; Langefeld, Carl D.; Le Marchand, Loic; Meister, Michael; Morgan, Ann W.; Raji, Olaide Y.; Risch, Angela; Rosenberger, Albert; Scherf, David; Steer, Sophia; Walshaw, Martin; Waters, Kevin M.; Wilson, Anthony G.; Wordsworth, Paul; Zienolddiny, Shanbeh; Tchetgen, Eric Tchetgen; Haiman, Christopher; Hunter, David J.; Plenge, Robert M.; Worthington, Jane; Christiani, David C.; Schaumberg, Debra A.; Chasman, Daniel I.; Altshuler, David; Voight, Benjamin; Kraft, Peter; Patterson, Nick; Price, Alkes L.


    Genetic case-control association studies often include data on clinical covariates, such as body mass index (BMI), smoking status, or age, that may modify the underlying genetic risk of case or control samples. For example, in type 2 diabetes, odds ratios for established variants estimated from low–BMI cases are larger than those estimated from high–BMI cases. An unanswered question is how to use this information to maximize statistical power in case-control studies that ascertain individuals on the basis of phenotype (case-control ascertainment) or phenotype and clinical covariates (case-control-covariate ascertainment). While current approaches improve power in studies with random ascertainment, they often lose power under case-control ascertainment and fail to capture available power increases under case-control-covariate ascertainment. We show that an informed conditioning approach, based on the liability threshold model with parameters informed by external epidemiological information, fully accounts for disease prevalence and non-random ascertainment of phenotype as well as covariates and provides a substantial increase in power while maintaining a properly controlled false-positive rate. Our method outperforms standard case-control association tests with or without covariates, tests of gene x covariate interaction, and previously proposed tests for dealing with covariates in ascertained data, with especially large improvements in the case of case-control-covariate ascertainment. We investigate empirical case-control studies of type 2 diabetes, prostate cancer, lung cancer, breast cancer, rheumatoid arthritis, age-related macular degeneration, and end-stage kidney disease over a total of 89,726 samples. In these datasets, informed conditioning outperforms logistic regression for 115 of the 157 known associated variants investigated (P-value = 1×10−9). The improvement varied across diseases with a 16% median increase in χ2 test statistics and a

  12. Informed conditioning on clinical covariates increases power in case-control association studies.

    Noah Zaitlen

    Full Text Available Genetic case-control association studies often include data on clinical covariates, such as body mass index (BMI, smoking status, or age, that may modify the underlying genetic risk of case or control samples. For example, in type 2 diabetes, odds ratios for established variants estimated from low-BMI cases are larger than those estimated from high-BMI cases. An unanswered question is how to use this information to maximize statistical power in case-control studies that ascertain individuals on the basis of phenotype (case-control ascertainment or phenotype and clinical covariates (case-control-covariate ascertainment. While current approaches improve power in studies with random ascertainment, they often lose power under case-control ascertainment and fail to capture available power increases under case-control-covariate ascertainment. We show that an informed conditioning approach, based on the liability threshold model with parameters informed by external epidemiological information, fully accounts for disease prevalence and non-random ascertainment of phenotype as well as covariates and provides a substantial increase in power while maintaining a properly controlled false-positive rate. Our method outperforms standard case-control association tests with or without covariates, tests of gene x covariate interaction, and previously proposed tests for dealing with covariates in ascertained data, with especially large improvements in the case of case-control-covariate ascertainment. We investigate empirical case-control studies of type 2 diabetes, prostate cancer, lung cancer, breast cancer, rheumatoid arthritis, age-related macular degeneration, and end-stage kidney disease over a total of 89,726 samples. In these datasets, informed conditioning outperforms logistic regression for 115 of the 157 known associated variants investigated (P-value = 1 × 10(-9. The improvement varied across diseases with a 16% median increase in χ(2 test statistics

  13. Radiation Hardening of Silicon Detectors

    Leroy, C; Glaser, M


    %RD48 %title\\\\ \\\\Silicon detectors will be widely used in experiments at the CERN Large Hadron Collider where high radiation levels will cause significant bulk damage. In addition to increased leakage current and charge collection losses worsening the signal to noise, the induced radiation damage changes the effective doping concentration and represents the limiting factor to long term operation of silicon detectors. The objectives are to develop radiation hard silicon detectors that can operate beyond the limits of the present devices and that ensure guaranteed operation for the whole lifetime of the LHC experimental programme. Radiation induced defect modelling and experimental results show that the silicon radiation hardness depends on the atomic impurities present in the initial monocrystalline material.\\\\ \\\\ Float zone (FZ) silicon materials with addition of oxygen, carbon, nitrogen, germanium and tin were produced as well as epitaxial silicon materials with epilayers up to 200 $\\mu$m thickness. Their im...

  14. Design of a total-dose radiation hardened monolithic CMOS DC-DC boost converter

    Liu Zhi; Yu Hongbo; Liu Youbao [Xi' an Institute of Microelectronics Technology, Xi' an 710054 (China); Ning Hongying, E-mail: [Xi' an University of Technology, Xi' an 710048 (China)


    This paper presents the design and implementation of a monolithic CMOS DC-DC boost converter that is hardened for total dose radiation. In order to improve its radiation tolerant abilities, circuit-level and device-level RHBD (radiation-hardening by design) techniques were employed. Adaptive slope compensation was used to improve the inherent instability. The H-gate MOS transistors, annular gate MOS transistors and guard rings were applied to reduce the impact of total ionizing dose. A boost converter was fabricated by a standard commercial 0.35 {mu}m CMOS process. The hardened design converter can work properly in a wide range of total dose radiation environments, with increasing total dose radiation. The efficiency is not as strongly affected by the total dose radiation and so does the leakage performance. (semiconductor integrated circuits)

  15. Influence and Analysis of Concentrate Degree of Plasma Arc for Heat Process of Hardening Treatment

    WANG Shuo-gui; YAN Hong-ri


    According to the practicable model of the plasma arc surface quench, the influence law of the heat process、cooling course、 temperature field about surface quench treatment by plasma arc due to the concentrate degree of plasma arc heat source are discussed in this paper. It shows that the concentrate degree of plasma arc heat source can change the width of the hardening zone and can not change the maximum harden depth. With the increase of the concentrate degree, the area of the heat influence zone is decreased and its shape is narrowed after the heat source. Relative to cooling rate, the influence of the heat source concentrate degree for heat absorption is bigger. The correctness of the practical model are proved with experimental results for quench hardening of 45# steel by plasma arc.

  16. Influence and Analysis of Concentrate Degree of Plasma Arc for Heat Process of Hardening Treatment

    WANGShuo-gui; YANHong-ri


    According to the practicable model of the plasma arc surtace quench, the influence law ot me heat process, cooling course, temperature field about surface quench treatment by plasma arc due to the concentrate degree of plasma arc heat source are discussed in this paper. It shows that the concentrate degree of plasma arc heat source can change the width of the hardening zone and can not change the maximum harden depth. With the increase of the concentrate degree, the area of the heat influence zone is decreased and its shape is narrowed after the heat source. Relative to cooling rate, the influence of the heat source concentrate degree for heat absorption is bigger. The correctness of the practical model are proved with experimental results for quench hardening of 45# steel by plasma arc.

  17. Raising the heat and wear resistances of hardened carbon steels by friction strengthening treatment

    Makarov, A. V.; Korshunov, L. G.; Malygina, I. Yu.; Solodova, I. L.


    The effect of friction treatment by a hard-alloy indenter on the microhardness and resistance to the heat-induced softening upon tempering of hardened medium-and high-carbon steels at 100-600°C is studied. The x-ray and electron microscopy methods are used to determine the causes of the increase in the heat resistance of the friction-strained steel surfaces. A comparative analysis of the effect of the hardening treatment by a hard-alloy indenter and by abrasive particles on the friction-induced heat resistance is performed for the case of high-speed friction treatment of a high-carbon laser-hardened steel.

  18. Genotypic variation in morphology and freezing resistance of Eucalyptus globulus seedlings subjected to drought hardening in nursery

    Coopman, Rafael E.; Jara,Jorge C; Escobar,Rene; Luis J Corcuera; Bravo,Leon A


    Eucalyptus globulus Labill is one of the most planted species in Chile, because of its fast growth and superior pulp qualities. Nevertheless, the incidence of drought and frost damage immediately after planting is frequent. The purpose of this work was to study the effect of drought hardening on frost resistance and on variations in morphological traits that may increase drought resistance at nursery phase in four genotypes of E. globulus Labill. Drought hardening treatments consisted in indu...

  19. Empirical beam hardening correction (EBHC) for CT

    Kyriakou, Yiannis; Meyer, Esther; Prell, Daniel; Kachelriess, Marc [Institute of Medical Physics, University of Erlangen-Nuernberg, 91052 Erlangen (Germany)


    Purpose: Due to x-ray beam polychromaticity and scattered radiation, attenuation measurements tend to be underestimated. Cupping and beam hardening artifacts become apparent in the reconstructed CT images. If only one material such as water, for example, is present, these artifacts can be reduced by precorrecting the rawdata. Higher order beam hardening artifacts, as they result when a mixture of materials such as water and bone, or water and bone and iodine is present, require an iterative beam hardening correction where the image is segmented into different materials and those are forward projected to obtain new rawdata. Typically, the forward projection must correctly model the beam polychromaticity and account for all physical effects, including the energy dependence of the assumed materials in the patient, the detector response, and others. We propose a new algorithm that does not require any knowledge about spectra or attenuation coefficients and that does not need to be calibrated. The proposed method corrects beam hardening in single energy CT data. Methods: The only a priori knowledge entering EBHC is the segmentation of the object into different materials. Materials other than water are segmented from the original image, e.g., by using simple thresholding. Then, a (monochromatic) forward projection of these other materials is performed. The measured rawdata and the forward projected material-specific rawdata are monomially combined (e.g., multiplied or squared) and reconstructed to yield a set of correction volumes. These are then linearly combined and added to the original volume. The combination weights are determined to maximize the flatness of the new and corrected volume. EBHC is evaluated using data acquired with a modern cone-beam dual-source spiral CT scanner (Somatom Definition Flash, Siemens Healthcare, Forchheim, Germany), with a modern dual-source micro-CT scanner (TomoScope Synergy Twin, CT Imaging GmbH, Erlangen, Germany), and with a modern

  20. Optimization of hardening/softening behavior of plane frame structures using nonlinear normal modes

    Dou, Suguang; Jensen, Jakob Søndergaard


    /softening behavior of nonlinear mechanical systems. The iterative optimization procedure consists of calculation of nonlinear normal modes, solving an adjoint equation system for sensitivity analysis and an update of design variables using a mathematical programming tool. We demonstrate the method with examples......Devices that exploit essential nonlinear behavior such as hardening/softening and inter-modal coupling effects are increasingly used in engineering and fundamental studies. Based on nonlinear normal modes, we present a gradient-based structural optimization method for tailoring the hardening...

  1. Improving mitochondrial bioenergetics under ischemic conditions increases warm ischemia tolerance in the kidney.

    Szeto, Hazel H; Liu, Shaoyi; Soong, Yi; Birk, Alexander V


    Ischemia time during partial nephrectomy is strongly associated with acute and chronic renal injury. ATP depletion during warm ischemia inhibits ATP-dependent processes, resulting in cell swelling, cytoskeletal breakdown, and cell death. The duration of ischemia tolerated by the kidney depends on the amount of ATP that can be produced with residual substrates and oxygen in the tissue to sustain cell function. We previously reported that the rat can tolerate 30-min ischemia quite well but 45-min ischemia results in acute kidney injury and progressive interstitial fibrosis. Here, we report that pretreatment with SS-20 30 min before warm ischemia in the rat increased ischemia tolerance from 30 to 45 min. Histological examination of kidney tissues revealed that SS-20 reduced cytoskeletal breakdown and cell swelling after 45-min ischemia. Electron microscopy showed that SS-20 reduced mitochondrial matrix swelling and preserved cristae membranes, suggesting that SS-20 enhanced mitochondrial ATP synthesis under ischemic conditions. Studies with isolated kidney mitochondria showed dramatic reduction in state 3 respiration and respiratory control ratio after 45-min ischemia, and this was significantly improved by SS-20 treatment. These results suggest that SS-20 increases efficiency of the electron transport chain and improves coupling of oxidative phosphorylation. SS-20 treatment after ischemia also significantly reduced interstitial fibrosis. These new findings reveal that enhancing mitochondrial bioenergetics may be an important target for improving ischemia tolerance, and SS-20 may serve well for minimizing acute kidney injury and chronic kidney disease following surgical procedures such as partial nephrectomy and transplantation.

  2. Third-party punishment increases cooperation in children through (misaligned) expectations and conditional cooperation.

    Lergetporer, Philipp; Angerer, Silvia; Glätzle-Rützler, Daniela; Sutter, Matthias


    The human ability to establish cooperation, even in large groups of genetically unrelated strangers, depends upon the enforcement of cooperation norms. Third-party punishment is one important factor to explain high levels of cooperation among humans, although it is still somewhat disputed whether other animal species also use this mechanism for promoting cooperation. We study the effectiveness of third-party punishment to increase children's cooperative behavior in a large-scale cooperation game. Based on an experiment with 1,120 children, aged 7 to 11 y, we find that the threat of third-party punishment more than doubles cooperation rates, despite the fact that children are rarely willing to execute costly punishment. We can show that the higher cooperation levels with third-party punishment are driven by two components. First, cooperation is a rational (expected payoff-maximizing) response to incorrect beliefs about the punishment behavior of third parties. Second, cooperation is a conditionally cooperative reaction to correct beliefs that third party punishment will increase a partner's level of cooperation.

  3. Presence of riparian vegetation increases biotic condition of fish assemblages in two Brazilian reservoirs

    Fabio Cop Ferreira


    Full Text Available Abstract The riparian vegetation in lakes and reservoirs is source of course wood structures such as trunks and branches and is used as sheltering, spawning and foraging habitats for fishes. The reduction of these submerged structures can thus, affect the composition and structure of fish assemblages in reservoirs. Aim To evaluate the influence of riparian vegetation on the biotic condition of fish assemblage by adapting the Reservoir Fish Assemblage Index (RFAI to two reservoirs in the Upper Paranapanema river basin, São Paulo State, Brazil. Methods The RFAI was adapted from metrics related to the functional characteristics and composition of fish assemblages through a protocol of metric selection and validation, and to its response to the presence of riparian vegetation. Results The final RFAI was composed by nine metrics, been lower in sites without riparian vegetation as consequence of the predominance of larger individuals and the percent of piscivorous and detritivorous fishes. Conclusions These results suggest that increasing shore habitat complexity in reservoirs by maintaining riparian vegetation increases fish biotic integrity.

  4. Continuous Hardening During Isothermal Aging at 723 K (450 °C) of a Precipitation Hardening Stainless Steel

    Celada-Casero, Carola; Chao, Jesús; Urones-Garrote, Esteban; San Martin, David


    The isothermal aging behavior of a cold-rolled precipitation hardening stainless steel has been studied at 723 K (450 °C) for holding times up to 72 hours. The precipitation hardening has been investigated using microhardness Vickers (Hv), thermoelectric power (TEP) measurements, and tensile testing. Microhardness compared to TEP measurements is more sensitive to detect the initial stages of aging. Two precipitation regimes have been observed: the first one related to the formation of Cu-clusters for aging times below 1 hour and a second one associated with formation of Ni-rich precipitates. The results show that the material exhibits an outstanding continuous age strengthening response over the aging time investigated, reaching a hardness of 710 ± 4 HV1 and an ultimate tensile strength ( σ UTS) of 2.65 ± 0.02 GPa after 72 hours. Engineering stress-plastic strain curves reveal that the strength increases and the ductility decreases as the aging time increases. However, after prolonged holding times (24-72 hours) and, although small, a rise in both the strength and the total elongation is observed. The precipitation kinetics can be well predicted over the entire range of aging times by the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. Finally, a reliable linear hardness-yield strength correlation has been found, which enables a rapid evaluation of the strength from bulk hardness measurements.

  5. Dislocation Starvation and Exhaustion Hardening in Mo-alloy Nanofibers

    Chisholm, Claire [University of California, Berkeley & LBNL; Bei, Hongbin [ORNL; Lowry, M. B. [University of California, Berkeley; Oh, Jason [Hysitron, Inc., MN; Asif, S.A. Syed [Hysitron, Inc., MN; Warren, O. [Hysitron, Inc., MN; Shan, Zhiwei [Xi' an Jiaotong University, China & Hysitron, Inc., MN; George, Easo P [ORNL; Minor, Andrew [University of California, Berkeley & LBNL


    The evolution of defects in Mo alloy nanofibers with initial dislocation densities ranging from 0 to 1.6 1014 m2 were studied using an in situ push-to-pull device in conjunction with a nanoindenter in a transmission electron microscope. Digital image correlation was used to determine stress and strain in local areas of deformation. When they had no initial dislocations the Mo alloy nanofibers suffered sudden catastrophic elongation following elastic deformation to ultrahigh stresses. At the other extreme fibers with a high dislocation density underwent sustained homogeneous deformation after yielding at much lower stresses. Between these two extremes nanofibers with intermediate dislocation densities demonstrated a clear exhaustion hardening behavior, where the progressive exhaustion of dislocations and dislocation sources increases the stress required to drive plasticity. This is consistent with the idea that mechanical size effects ( smaller is stronger ) are due to the fact that nanostructures usually have fewer defects that can operate at lower stresses. By monitoring the evolution of stress locally we find that exhaustion hardening causes the stress in the nanofibers to surpass the critical stress predicted for self-multiplication, supporting a plasticity mechanism that has been hypothesized to account for the rapid strain softening observed in nanoscale bcc materials at high stresses.

  6. Increased ophthalmic acid production is supported by amino acid catabolism under fasting conditions in mice.

    Kobayashi, Sho; Lee, Jaeyong; Takao, Toshifumi; Fujii, Junichi


    Glutathione (GSH) plays pivotal roles in antioxidation and detoxification. The transsulfuration pathway, in conjunction with methionine metabolism, produces equimolar amounts of cysteine (Cys) and 2-oxobutyric acid (2OB). The resulting 2OB is then converted into 2-aminobutyric acid (2AB) by a transaminase and is utilized as a substitute for Cys by the GSH-synthesizing machinery to produce ophthalmic acid (OPT). By establishing a method for simultaneously measuring Cys, GSH, and OPT by liquid chromatography-mass spectrometry, we found that fasting causes an elevation in OPT levels in the liver and blood plasma, even though the levels of Cys and GSH are decreased. Autophagy was activated, but the levels of GSH/OPT-synthesizing enzymes remained unchanged. After 6 h of fasting, the mice were given 1% 2AB and/or 5% glucose in the drinking water for an additional 24 h and the above metabolites analyzed. 2AB administration caused an increase in OPT levels, and, when glucose was co-administered with 2AB, the levels of OPT were elevated further but GSH levels were decreased somewhat. These results suggest that, while Cys is utilized for glyconeogenesis under fasting conditions, reaching levels that were insufficient for the synthesis of GSH, 2OB was preferentially converted to 2AB via amino acid catabolism and was utilized as a building block for OPT. Thus the consumption of Cys and the parallel elevation of 2AB under fasting conditions appeared to force γ-glutamylcysteine synthetase to form γ-glutamyl-2AB, despite the fact that the enzyme has a higher Km value for 2AB than Cys. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Homes of low-income minority families with asthmatic children have increased condition issues.

    Pacheco, Christina M; Ciaccio, Christina E; Nazir, Niaman; Daley, Christine M; DiDonna, Anita; Choi, Won S; Barnes, Charles S; Rosenwasser, Lanny J


    The home is increasingly associated with asthma. It acts both as a reservoir of asthma triggers and as a refuge from seasonal outdoor allergen exposure. Racial/ethnic minority families with low incomes tend to reside in neighborhoods with low housing quality. These families also have higher rates of asthma. This study explores the hypothesis that black and Latino urban households with asthmatic children experienced more home mechanical, structural condition-related areas of concern than white households with asthmatic children. Participant families (n = 140) took part in the Kansas City Safe and Healthy Homes Program, had at least one asthmatic child, and met income qualifications of no more than 80% of local median income; many were below 50%. Families self-identified their race. Homes were assessed by environmental health professionals using a standard set of criteria and a specific set of on-site and laboratory sampling and analyses. Homes were given a score for areas of concern between 0 (best) and 53 (worst). The study population self-identified as black (46%), non-Latino white (26%), Latino (14.3%), and other (12.9%). Mean number of areas of concern were 18.7 in Latino homes, 17.8 in black homes, 13.3 in other homes, and 13.2 in white homes. Latino and black homes had significantly more areas of concern. White families were also more likely to be in the upper portion of the income. In this set of 140 low-income homes with an asthmatic child, households of minority individuals had more areas of condition concerns and generally lower income than other families.

  8. Simulation-aided investigation of beam hardening induced errors in CT dimensional metrology

    Tan, Ye; Kiekens, Kim; Welkenhuyzen, Frank


    Industrial X-ray CT systems are increasingly used as dimensional measuring machines. However, micron level accuracy is not always achievable yet. The measurement accuracy is influenced by many factors, such as workpiece properties, X-ray settings, beam hardening and calibration methods [1-4]. Since...

  9. Mx1-cre mediated Rgs12 conditional knockout mice exhibit increased bone mass phenotype.

    Yang, Shuying; Li, Yi-Ping; Liu, Tongjun; He, Xiaoning; Yuan, Xue; Li, Chunyi; Cao, Jay; Kim, Yunjung


    Regulators of G-protein Signaling (Rgs) proteins are the members of a multigene family of GTPase-accelerating proteins (GAP) for the Galpha subunit of heterotrimeric G-proteins. Rgs proteins play critical roles in the regulation of G protein couple receptor (GPCR) signaling in normal physiology and human diseases such as cancer, heart diseases, and inflammation. Rgs12 is the largest protein of the Rgs protein family. Some in vitro studies have demonstrated that Rgs12 plays a critical role in regulating cell differentiation and migration; however its function and mechanism in vivo is largely unknown. Here, we generated a floxed Rgs12 allele (Rgs12(flox/flox) ) in which the exon 2, containing both PDZ and PTB_PID domains of Rgs12, was flanked with two loxp sites. By using the inducible Mx1-cre and Poly I:C system to specifically delete Rgs12 at postnatal 10 days in interferon-responsive cells including monocyte and macrophage cells, we found that Rgs12 mutant mice had growth retardation with the phenotype of increased bone mass. We further found that deletion of Rgs12 reduced osteoclast numbers and had no significant effect on osteoblast formation. Thus, Rgs12(flox/flox) conditional mice provide a valuable tool for in vivo analysis of Rgs12 function and mechanism through time- and cell-specific deletion of Rgs12.

  10. Microstructure Changes in Hardened Cement Paste after Freezing – Thawing Cycles

    Gintautas SKRIPKIŪNAS


    Full Text Available This article analyses the results of the freezing – thawing with deicing salt test where changes in the microstructure of the surface layer in contact with aggressive environment of hardened cement paste produced with and without sodium silicate (hereinafter NTS admixture were observed after freeze-thaw cycles in the presence of calcium chloride. After 56 cycles of freezing – thawing with deicing salt test micro-cracks and cavities were observed in the microstructure of the surface layer of hardened cement paste with and without NTS admixture. In the case of hardened cement paste with NTS admixture changes in the microstructure of the surface layer are less prominent: the number and size of cavities and micro-cracks are smaller. The test revealed that compressive stress, which before freezing – thawing with deicing salt test was very similar in hardened cement paste with and without NTS admixture (85.4 MPa and 82.8 MPa respectively, changed after 56 cycles of freezing – thawing with deicing salt test as follows: reduced by 39.5 % in concrete without NTS admixture and increased slightly (2.5 % in hardened cement paste with NTS admixture. Based on the test results the authors arrived at the conclusion that sodium silicate solution can be effectively used to extend the useful life of hardened cement paste exposed to freeze-thaw cycles and affected by CaCl2.DOI:

  11. Configurable Radiation Hardened High Speed Isolated Interface ASIC Project

    National Aeronautics and Space Administration — NVE Corporation will design and build an innovative, low cost, flexible, configurable, radiation hardened, galvanically isolated, interface ASIC chip set that will...

  12. Additive strengthening mechanisms in dispersion hardened polycrystals

    Hansen, Niels; Ralph, B.


    Tensile data from polycrystalline samples of copper dispersion strengthened by alumina are analysed. The basis of this analysis is to look at the strain range from 0.05 to 0.20 where the stress-strain curves show a parabolic hardening behaviour and are parallel to one another. The means by which...... the dislocation density contributions from each of these three sources. The type of additivity suggested here not only gives very good agreement with the stress-strain data but it also uses and is in accord with the experimental measurements of dislocation densities made using transmission electron microscopy....

  13. Condition For Strain-Hardening In Ecc Uniaxial Test Specimen

    Dick-Nielsen, Lars; Stang, Henrik; Poulsen, Peter Noe


    and infinite sheets under uniaxial tension. The crack is assumed to be cohesive and the cohesive law applied takes into account fiber as well as mortar properties. It is shown that the maximum crack opening observed during crack propagation in various test specimen geometries is small, 20 m and also small...... compared to typical deformations at peak bridging stress. The requirement of a minimum complementary energy for the fiber bridging curve is found not to be relevant in the aim of controlling the crack opening during crack propagation....

  14. The development of high strength corrosion resistant precipitation hardening cast steels

    Abrahams, Rachel A.

    , give poor estimates of secondary phases in PHCSS. No measureable retained austenite was observed in any of the CB7Cu-1 steels studied, in spite of the fact that austenite is predicted by the constitution diagrams. A designed experiment using computationally derived phase equilibrium diagrams and actual experimental tests on CB7Cu of different compositions suggests that the ferrite phase is less stable than the constitution diagrams for austenitic stainless steels suggest. Delta ferrite was also more stable in slower-cooled sand cast material as compared to thin, fast-cooled investment cast material. High temperature solutionizing treatments were effective in dissolving delta ferrite at temperatures above 1900°F (˜1040°C). Delta ferrite dissolution was found to proceed at high rates during initial dissolution, and then was found to slow after 1 hour. Diffusion during the later stages is well-predicted by classical diffusion models. Repeated solution treatments were found to modestly increase both ductility and strength, likely due to subgrain refinement through austenite regrowth. Multistaged aging provided superior strength and toughness increases over similarly peak-aged and near peak-aged material aged at a single temperature. Peak-aged material fractography suggested that low energy quasi-cleavage fracture was likely due to age precipitate embrittlement along with some nucleation of MnS particulates at prior austenite grain boundaries. Yield strengths approaching 190 ksi (1310MPa) can be achieved in CB7Cu-1 if appropriate best-practices "+" processing techniques are used. This includes hot isostatic processing to reduce solidification segregation and heal microporosity, high temperature homogenization for effective age hardening and ferrite reduction, double-cycle solutionizing for structure refinement, and multistaged age strengthening for finer precipitate control. The experimental prototype 11-11PH (Fe-Ni-Cr-Ti-Mo) casting alloys was cast and was found to be

  15. Hardening by annealing and softening by deformation in nanostructured metals

    Huang, X.; Hansen, N.; Tsuji, N.


    -dislocation and dislocation-interface reactions, such that heat treatment reduces the generation and interaction of dislocations, leading to an increase in strength and a reduction in ductility. A subsequent deformation step may restore the dislocation structure and facilitate the yielding process when the metal is stressed......We observe that a nanostructured metal can be hardened by annealing and softened when subsequently deformed, which is in contrast to the typical behavior of a metal. Microstructural investigation points to an effect of the structural scale on fundamental mechanisms of dislocation....... As a consequence, the strength decreases and the ductility increases. These observations suggest that for materials such as the nanostructured aluminum studied here, deformation should be used as an optimizing procedure instead of annealing....

  16. Sinter-hardening of Ni-Mo pre-alloyed powders with tungsten addition

    L.A. Dobrzański


    Full Text Available Purpose: Purpose of this paper was to present the benefits of powder metallurgy technology and development ofsinter-hardening process. The mechanical properties, focusing in particular on hardness and wear resistance, oftwo different carbon levels pre-alloyed steel powders processed with sinter-hardening method, were described.Microstructure characteristic of produced sinter-hardened Ni-Mo steels with increasing amount of tungsten(from 0 to 0.3% wt. was taken under consideration.Design/methodology/approach: Different compositions have been tested in order to investigate the influenceof various tungsten additions into low (0.4% and high (0.6% carbon content of pre-alloyed steel powders.Powders, with addition of 0.7% lubricant, were pressed in a 2000kN hydraulic press. De-waxing process at550ºC for 60 minutes in a fully nitrogen atmosphere was performed before the sintering. Sintering was carriedout in vacuum furnace with argon backfilling. The furnace was equipped with a cooling zone to provideaccelerated cooling from the sintering temperature. Green compacts were sintered at the temperature 1120ºC for1 hour and rapidly cooled with a rate 2.5ºC/s.Findings: The applied sinter-hardening process resulted with achievement of material characterized by goodwear resistance. The investigation of Ni-Mo and Ni-Mo-W sinter-hardened steels with low and high carboncontent proved that applied process of sintering under vacuum and rapid cooling brought expected outcome.Research limitations/implications: Considering the achieved outcome, it was revealed that chemical compositionand applied process of steels preparation, sinter-hardening with the cooling rate 2.5ºC/s, results in achieving materialswith relatively high hardness and significant resistance to abrasion. Anyhow, further research should be performed.Originality/value: Sinter-hardening of Ni-Mo pre-alloyed powders with the addition of different additions oftungsten, especially in terms of

  17. Mechanical Analysis of Concrete Specimen under Restrained Condition

    MA Xinwei; NIU Changren; R D Hooton


    In order to quantify the development of the tensile stresses and obtain a reliable estimation of the cracking risk, the concrete was subjected to restrained conditions. The fully restrained condition was achieved by keeping the length constant of a concrete specimen. Comparing the free shrinkage with the restrained shrinkage,tensile creep could be discriminated from shrinkage. The testing method was introduced in details, and the mechanical behaviors under tensile load were analyzed. Results show that concrete exhibits a pronounced viscoelasticity. Under restrained condition, the self induced tensile stress increases with time. The lower the water to cement ratio, the larger the tensile stress at the same age. The tensile creep of hardening concrete is much larger than that of hardened concrete. The relationships among autogenous shrinkage under free condition, elastic strain and creep under restrained condition are described, and the mathematical model for the calculation of elastic strain and creep is proposed.

  18. Hardened Client Platforms for Secure Internet Banking

    Ronchi, C.; Zakhidov, S.

    We review the security of e-banking platforms with particular attention to the exploitable attack vectors of three main attack categories: Man-in-the-Middle, Man-in-the-PC and Man-in-the-Browser. It will be shown that the most serious threats come from combination attacks capable of hacking any transaction without the need to control the authentication process. Using this approach, the security of any authentication system can be bypassed, including those using SecureID Tokens, OTP Tokens, Biometric Sensors and Smart Cards. We will describe and compare two recently proposed e-banking platforms, the ZTIC and the USPD, both of which are based on the use of dedicated client devices, but with diverging approaches with respect to the need of hardening the Web client application. It will be shown that the use of a Hardened Browser (or H-Browser) component is critical to force attackers to employ complex and expensive techniques and to reduce the strength and variety of social engineering attacks down to physiological fraud levels.

  19. Hardness variability in commercial and hardened technologies

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


    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.

  20. Aging of medium strength aluminum alloy friction stir welds produced by different process parameter after tensile strain hardening

    Cerri, Emanuela, E-mail:; Leo, Paola


    Effect of tool rotation rate and travel speed on aging of 6082T6 friction stir welds after tensile strain hardening were investigated using Vickers microhardness (HV) measurements and precipitation hardening concepts. Tensile tests were performed at constant strain rate up to natural fracture followed by aging at low and medium temperatures. The results showed that HV measured on strain hardened FSW joints was not very sensitive to travel speeds experienced during FSW process, at constant rotation rate; anyway, strain hardening was very effective on hardness and induce an average increase by 20–25% in the stirred zone (SZ). Strain hardening was also very effective on aging at 200 °C, while it was not at 300 °C. At this temperature, HV assumed uniform values along joint cross section. - Highlights: • FSW joints have been investigated after tensile deformation and aging. • Tensile strain hardening induces a 20–25% HV increment in the stirred zone. • Subsequent aging at 200 °C did not substantially modify hardness profiles. • After aging at 300 °C, HV values were uniform and lower than HV minimum.

  1. Influence of water hardening of the chorion on cadmium accumulation in medaka (Oryzias latipes) eggs.

    González-Doncel, Miguel; Larrea, Maite; Sánchez-Fortún, Sebastián; Hinton, David E


    This report describes a study in which in vitro fertilization methods were used to expose medaka (Oryzias latipes) eggs to cadmium (Cd(2+)). This approach was applied to address the differential sensitivity and cumulative potential of Cd(2+) when exposure was initiated early (before fertilization and water hardening of the chorion) versus later during embryo development (i.e., well after the chorion has undergone water hardening). Following range finding exposures (2.5, 10, 20, 40 or 80 mg/l) under artificially controlled experimental procedures, results from hatching success and embryo malformations showed the earlier exposure interval more sensitive than the assay involving only the embryonated egg. Subsequent accumulation studies have shown that the exposure initiated before fertilization apparently led to more Cd(2+) deposition in the chorion compared to the exposure during embryonated stages of the eggs. Similarly, values for total Cd(2+) indicated higher concentrations in those eggs exposed prior to--and during--water hardening. Results suggest an alteration of the properties of the zona radiata in the early-stage eggs, making it more permeable to the potential exit or entrance of waterborne agents even after water hardening. Ongoing studies must now address the development of more realistic exposure conditions of the gametes by using incubation media with osmolarities similar to surface waters, and by shortening duration for gamete exposure. Also, sensitive methods to localize Cd(2+) and to delineate the transfer from the chorion to the embryo are needed.

  2. Hardening kinetics investigation of alkali-activated binder by small amplitude oscillatory rheometry

    Rieger, D.; Kullová, L.; Čekalová, M.; Kovářík, T.


    In this study, the rheological behavior of geopolymeric inorganic binder was determined. This binder was synthesized by alkaline activation of mixture, comprising calcined claystone powder and milled blast furnace slag. As an alkaline activator of hardening process, the potassium silicate solution was used. For the investigation of hardening kinetics, the strain controlled small amplitude oscillatory rheometry was used with strain of 0.01%. The reproducibility and versatility of this method is demonstrated for determination of hardening process evolution. The changes of loss tangent shape were studied in this experiment and applied for determination of gelation time. All experiments were conducted at isothermal conditions in temperature range 27-70°C and parallel plate geometry. The results indicate that reaction kinetics is directly depending on temperature. The hardening kinetics was mathematically described and these calculations were compared with self-contained experiment conducted at 2°C. This experiment is described in details and the results of gelation time measurements confirmed calculated data.

  3. Optimization of Laser Beam Transformation Hardening by One Single Parameter

    Meijer, J.; Sprang, van I.


    The process of laser beam transformation hardening is principally controlled by two independent parameters, the absorbed laser power on a given area and the interaction time. These parameters can be transformed into two functional parameters: the maximum surface temperature and the hardening depth.

  4. [Hardening of dental tissue by CO2 laser radiation].

    Aboites, V; Díaz, O; Cuevas, F


    A study was conducted to test the effects of CO2 laser irradiation on dental tissue. It was found that hardening of the dental tissue occurs. This was observed qualitatively by direct observation and by X-ray radiography. The hardening produced was also quantitatively measured using a hardness-meter on Rockwell scale.

  5. Design and characterization of cellulose nanocrystal-enhanced epoxy hardeners

    Shane X. Peng; Robert J. Moon; Jeffrey P. Youngblood


    Cellulose nanocrystals (CNCs) are renewable, sustainable, and abundant nanomaterial widely used as reinforcing fillers in the field of polymer nanocomposites. In this study, two-part epoxy systems with CNC-enhanced hardeners were fabricated. Three types of hardeners, Jeffamine D400 (JD400), diethylenetriamine (DETA), and (±)-trans-1,2- diaminocyclohexane (DACH), were...

  6. An Oxygen-Permeation Treatment for Hardening Titanium Alloys

    MA Hong-yan; WANG Mao-cai; WEI Zheng; XIN Gong-chun


    In this paper, the characterization of oxygen permeation (OP) in titanium alloy TC11 at high temperature and the influence of oxygen solution layer on performances of substrate were characterized with the help of apparatus, such as TGA,SEM/EDAX, XRD, EPMA, Micro-hardness Tester, Two-body Abrasion Tester, Amsler Wear Test Machine, Potentiostat/Galvanostat Model 273 system. The results showed that there was a little shift in X-ray diffraction peaks of α and β phase during the OPT process as a result of oxygen solution. The OP treatment can significantly increase the surface hardness of titanium alloys and, accordingly, the abrasive wear resistance was improved. Titanium alloys with oxygen solution layer exhibited improved corrosion resistance both in 3.5 % NaCl and in 5 % HCl solution. Oxidation resistance of TC11 with oxygen solution layer at high temperature was also enhanced. The solution and hardening mechanisms were discussed based on the experimental results.

  7. Thermal Hardening: A New Seed Vigor Enhancement Tool in Rice

    Muhammad FAROOQ; S. M. A. BASRA; Nazir AHMAD; K. HAFEEZ


    In a laboratory study, indica and japonica rice (Oryza sativa L.) seeds were exposed to thermal hardening (heating followed by chilling followed by heating; chilling followed by heating followed by chilling; heating followed by chilling or chilling followed by heating). In indica rice, heating followed by chilling followed by heating resulted in decreased mean germination time, time to start germination, electrical conductivity of seed leachates, and time to 50% germination, as well as increased germination index, energy of germination, radicle and plumule length, root length, root/shoot ratio, root fresh and dry weight, radicle and plumule growth rate, and shoot fresh weight. In japonica rice, chilling followed by heating followed by chilling performed better than all other treatments, including control.

  8. Modeling of state parameter and hardening function for granular materials

    彭芳乐; 李建中


    A modified plastic strain energy as hardening state parameter for dense sand was proposed, based on the results from a series of drained plane strain tests on saturated dense Japanese Toyoura sand with precise stress and strain measurements along many stress paths. In addition, a unique hardening function between the plastic strain energy and the instantaneous stress path was also presented, which was independent of stress history. The proposed state parameter and hardening function was directly verified by the simple numerical integration method. It is shown that the proposed hardening function is independent of stress history and stress path and is appropriate to be used as the hardening rule in constitutive modeling for dense sand, and it is also capable of simulating the effects on the deformation characteristics of stress history and stress path for dense sand.

  9. Extreme temperatures increase the deleterious consequences of inbreeding under laboratory and semi-natural conditions

    Kristensen, Torsten Nygård; Barker, J. Stuart F.; Pedersen, Kamilla Sofie


    The majority of experimental studies of the effects of population bottlenecks on fitness are performed under laboratory conditions, which do not account for the environmental complexity that populations face in nature. In this study, we test inbreeding depression in multiple replicates of inbred...... when compared with non-inbred lines of Drosophila melanogaster under different temperature conditions. Egg-to-adult viability, developmental time and sex ratio of emerging adults are studied under low, intermediate and high temperatures under laboratory as well as semi-natural conditions. The results...... the sex ratio with more females relative to males emerging at low temperatures, suggesting that selection against males in pre-adult life stages is stronger at low temperatures. The coefficient of variation (CV) of egg-to-adult viability within and among lines is higher for inbred flies and generally...

  10. Increased performance of hydrogen production in microbial electrolysis cells under alkaline conditions.

    Rago, Laura; Baeza, Juan A; Guisasola, Albert


    This work reports the first successful enrichment and operation of alkaline bioelectrochemical systems (microbial fuel cells, MFC, and microbial electrolysis cells, MEC). Alkaline (pH=9.3) bioelectrochemical hydrogen production presented better performance (+117%) compared to conventional neutral conditions (2.6 vs 1.2 litres of hydrogen gas per litre of reactor per day, LH2·L(-1)REACTOR·d(-1)). Pyrosequencing results of the anodic biofilm showed that while Geobacter was mainly detected under conventional neutral conditions, Geoalkalibacter sp. was highly detected in the alkaline MFC (21%) and MEC (48%). This is the first report of a high enrichment of Geoalkalibacter from an anaerobic mixed culture using alkaline conditions in an MEC. Moreover, Alkalibacter sp. was highly present in the anodic biofilm of the alkaline MFC (37%), which would indicate its potentiality as a new exoelectrogen.

  11. Generalization of Conditioned Fear along a Dimension of Increasing Fear Intensity

    Dunsmoor, Joseph E.; Mitroff, Stephen R.; LaBar, Kevin S.


    The present study investigated the extent to which fear generalization in humans is determined by the amount of fear intensity in nonconditioned stimuli relative to a perceptually similar conditioned stimulus. Stimuli consisted of graded emotionally expressive faces of the same identity morphed between neutral and fearful endpoints. Two…

  12. Increased time to pregnancy is associated with suboptimal neurological condition of 2-year-olds

    Seggers, Jorien; Schendelaar, Pamela; Bos, Arend F.; Heineman, Maas Jan; Middelburg, Karin J.; Haadsma, Maaike L.; Hadders-Algra, Mijna


    Objective To evaluate whether time to pregnancy (TTP) is associated with neurological condition of 2-year-old children born to subfertile parents. Design Data collected in a prospective, assessor-blinded follow-up study were used for cross-sectional analyses. Patients Participants were the singleton

  13. Humid storage conditions increase the dissolution rate of diazepam from solid dispersions prepared by melt agglomeration

    Jørgensen, Anna Cecilia; Torstenson, Anette Seo


    The purpose of this study is to investigate the effect of cooling mode and storage conditions on the dissolution rate of a solid dispersion prepared by melt agglomeration. The aim has been to relate this effect to the solid state properties of the agglomerates. The cooling mode had an effect on t...

  14. Age hardening characteristics and mechanical behavior of Al-Cu-Li-Zr-In alloys

    Wagner, John A.


    An investigation was conducted to determine the age-hardening response and cryogenic mechanical properties of superplastic Al-Cu-Li-Zr-In alloys. Two alloys with compositions Al-2.65Cu-2.17Li-O.13Zr (baseline) and Al-2.60Cu-2.34Li-0.16Zr-0.17In were scaled-up from 30 lb permanent mold ingots to 350 lb DC (direct chill) ingots and thermomechanically processed to 3.2 mm thick sheet. The microstructure of material which contained the indium addition was partially recrystallized compared to the baseline suggesting that indium may influence recrystallization behavior. The indium-modified alloy exhibited superior hardness and strength compared to the baseline alloy when solution-heat-treated at 555 C and aged at 160 C or 190 C. For each alloy, strength increased and toughness was unchanged or decreased when tested at - 185 C compared to ambient temperature. By using optimized heat treatments, the indium-modified alloy exhibited strength levels approaching those of the baseline alloy without deformation prior to aging. The increase in strength of these alloys in the T6 condition make them particularly attractive for superplastic forming applications where post-SPF parts cannot be cold deformed to increase strength.

  15. Saturation behavior of irradiation hardening in F82H irradiated in the HFIR

    Hirose, T. [Blanket Engineering Group, Japan Atomic Energy Agency, Naka, Ibaraki (Japan); Shiba, K.; Tanigawa, H.; Ando, M. [Japan Atomic Energy Agency, Tokai-mura, Naga-gun, Ibaraki-ken (Japan); Klueh, R.L. [Oak Ridge National Laboratory, TN (United States); Stoller, R. [ORNL - Oak Ridge National Laboratory, Materials Science and Technology Div., Oak Ridge, AK TN (United States)


    Full text of publication follows: Post irradiation tensile tests on reduced activation ferritic/martensitic steel, F82H have been conducted over the past two decades using Japan Materials Testing Reactor (JMTR) of JAEA, and Fast Flux Testing Facility (FFTF) of PNNL and High Flux Isotope Reactor (HFIR) of ORNL, USA, under Japan/US collaboration programs. According to these results, F82H does not demonstrate irradiation hardening above 673 K up to 60 dpa. The current study has been concentrated on hardening behavior at temperature around 573 K. A series of low temperature irradiation experiment has been conducted at the HFIR under the international collaborative research between JAEA/US-DOE. In this collaboration, the irradiation condition is precisely controlled by the well matured capsule designing and instrumentation. This paper summarizes recent results of the irradiation experiments focused on F82H and its modified steels compared with the irradiation properties database on F82H. Post irradiation tensile tests have been conducted on the F82H and its modified steels irradiated at 573 K and the dose level was up to 25 dpa. According to these results, irradiation hardening of F82H is saturated by 9 dpa and the as-irradiated 0.2 % proof stress is less than 1 GPa at ambient temperature. The deterioration of total elongation was also saturated by 9 dpa irradiation. The ductility of some modified steels which showed larger total elongation than that of F82H before irradiation become the same level as that of standard F82H steel after irradiation, even though its magnitude of irradiation hardening is smaller than that of F82H. This suggests that the more ductile steel demonstrates the more ductility loss at this temperature, regardless to the hardening level. The difference in ductility loss behavior between various tensile specimens will be discussed as the ductility could depend on the specimen dimension. (authors)

  16. Jerky loads on surface-hardened gears

    Rettig, H.; Wirth, X.


    Damage occurs again and again in practice in the form of transmissions with surface hardened gears which break after a very long operating time (explained by seldom occurring jerky loads). Gear drives are frequently exposed to jerky stresses which are greater than their fatigue limit. These stresses are considered in gear calculations, first, by shock factors when the transmission is to be designed as high endurance with regard to overloads and, second, in the form of operating ratios when the design is to be time enduring with regard to overloads. The size of the operating ratio depends not only on torque characteristics, drive and processing machine, but also on the material and heat treatment.

  17. Lowering of the yield ratio in solution hardened interstitial-free steel by employing transformation microstructure; Hentai soshiki wo riyoshita koyo kyoka IF ko no teikofukuhika

    Sakata, K.; Okuda, K.; Seto, K.; Obara, T. [Kawasaki Steel Corp., Tokyo (Japan)


    Discussions were given for the purpose of reducing yield ratio (yield stress/tensile strength) of ultra-low carbon steel, which has been solution hardened mainly with P, by utilizing transformation microstructure resulted from dual phase annealing. An experiment was performed to investigate the relationship between kinds and amounts of solid solution elements as well as dual phase annealing conditions necessary for lowering of yield radio. The 0.10%P-1.5%MN-0.5%Si steel with a large amount of P has a high yield ratio in annealing in the single ferrite phase region, but the yield ratio decreases remarkably as a result of the dual phase annealing. Reduction of the yield ratio in the dual phase annealing corresponds with reduction in yield growth in non-conditioned materials. Reduction of the yield ratio due to the dual phase annealing may be possible even if Mn is increased, but the strengths (tensile strength and yield strength) increase largely in association with increase in {gamma} factor ratio. Dual phase distribution of ferrite and austenite as solution hardened elements and the size of dual phase temperature region were estimated by using the Thermo-Calc. High Mn steel also shows behavior similar to that in 0.10%P-1.5%Mn-0.5%Si steel with a large amount of P if no B is added. 13 refs., 9 figs., 2 tabs.

  18. Hall coefficient measurement for residual stress assessment in precipitation hardened IN718 nickel-base superalloy

    Velicheti, Dheeraj; Nagy, Peter B.; Hassan, Waled


    We investigated the feasibility of residual stress assessment based on Hall coefficient measurements in precipitation hardened IN718 nickel-base superalloy. As a first step, we studied the influence of microstructural variations on the galvanomagnetic properties of IN718 nickel-base superalloy. We found that the Hall coefficient of IN718 increases from ≈ 8.0×10-11 m3/C in its fully annealed state of 15 HRC Rockwell hardness to ≈ 9.4×10-11 m3/C in its fully hardened state of 45 HRC. We also studied the influence of cold work, i.e., plastic deformation, at room temperature and found that cold work had negligible effect on the Hall coefficient of fully annealed IN718, but significantly reduced it in hardened states of the material. For example, measurements conducted on fully hardened IN718 specimens showed that the Hall coefficient decreased more or less linearly with cold work from its peak value of ≈ 9.4×10-11 m3/C in its intact state to ≈ 9.0×10-11 m3/C in its most deformed state of 22% plastic strain. We also studied the influence of applied stress and found that elastic strain significantly increases the Hall coefficient of IN718 regardless of the state of hardening. The relative sensitivity of the Hall coefficient to elastic strain was measured as a unitless gauge factor K that is defined as the ratio of the relative change of the Hall coefficient ΔRH/RH divided by the axial strain ɛ = σ/E, where σ is the applied uniaxial stress and E is the Young's modulus of the material. We determined that the galvanomagnetic gauge factor of IN718 is κ ≈ 2.6 - 2.9 depending on the hardness level. Besides the fairly high value of the gauge factor, it is important that it is positive, which means that compressive stress in surface-treated components decreases the Hall coefficient in a similar way as plastic deformation does, therefore the unfortunate cancellation that occurs in fully hardened IN718 in the case of electric conductivity measurements will not

  19. MDA-MET-conditioned-medium augments the chemoattractant-dependent migration of MDA-MET cells towards hFOB-conditioned medium and increases collagenase activity.

    Chin-Quee, Karis; Donahue, Henry J


    Metastasis of breast cancer displays site-specificity towards bone. Recently, studies have emerged indicating that primary tumors may remotely influence creation of a pre-metastatic niche. In this study, we used human fetal osteoblastic cells and MDA-MET, a metastatic and preferentially bone homing derivative of the breast cancer cell line MDA-MB-231. We examined 1) whether secreted factors from MDA-MET cells increase generation of chemoattractants by human foetal osteoblastic cells 2) whether MDA-MET cells were responsive to these chemoattractants and 3) the identity of these chemoattractants. Human foetal osteoblastic cells were treated with conditioned medium of MDA-MET cells for 24 hours and then washed with phosphate-buffered saline. Serum-free replacement medium was conditioned by treated hFOB cells for 18 hours, before its use in in vitro quantification of MDA-MET migration. We also quantified collagen levels and collagenase activity in conditioned medium from human foetal osteoblastic cells. Conditioned medium from human foetal osteoblastic cells that had been treated with MDA-MET-conditioned medium attracted more MDA-MET cells than hFOB cells pre-exposed to their own medium. This conditioned medium had increased collagenase activity. The addition of bacterial collagenase removed the ability of conditioned medium from human foetal osteoblastic cells to attract MDA-MET cells. Our data suggest that an increase in collagenase activity in osteoblastic cells induced by their exposure to breast cancer cell-secreted factors may increase their ability to attract breast cancer cells.

  20. Spectral Hardening and Geoeffectiveness of Solar Flares

    Jain, R.; Kumar, S.; Dave, H.; Deshpande, M. R.

    We present the results of a few typical flares that observed by the first space borne solar astronomy experiment of India namely "Solar X-ray Spectrometer (SOXS)" mission, which has completed one year of its successful operation in geostationary orbit. The SOXS mission onboard GSAT-2 Indian spacecraft was launched successfully by GSLV-D2 rocket on 08 May 2003 to study the energy release and particle acceleration in solar flares. The SOXS is composed of two independent payloads viz. SOXS Low Energy Detector (SLD) payload, and SOXS High Energy Detector (SHD) payload. We restrict our presentation to SLD payload that designed, developed and fabricated by Physical Research Laboratory (PRL) in collaboration with Space Application Centre (SAC), Ahmedabad and ISRO Satellite Centre (ISAC), Bangalore of Indian Space Research Organization (ISRO). We briefly present the scientific objectives and instrumentation of the SLD payload. The SLD payload employs the state-of-art solid state detectors viz. Si PIN and CZT detectors, which reveal sub-keV spectral and 100ms temporal resolution characteristics that are necessary to study the spectral response of the flare components. The dynamic range of Si and CZT detectors is 4-25 and 4-56 keV respectively. The SLD has observed more than 140 flares of C and M class since its commissioning in the orbit. We present the X-ray emission characteristics of a few typical flares in view of their spectral hardening and geo-effectiveness. We extend our study of these flares to optical and radio waveband observations in order to improve the relationship of X-ray spectral hardening and geo-effectiveness. The flares with harder spectra and associated with small or large CME, and radio emission at frequencies above 10 GHz are found geo-effective.

  1. Hardening of ODS ferritic steels under irradiation with high-energy heavy ions

    Ding, Z. N.; Zhang, C. H.; Yang, Y. T.; Song, Y.; Kimura, A.; Jang, J.


    Influence of the nanoscale oxide particles on mechanical properties and irradiation resistance of oxide-dispersion-strengthened (ODS) ferritic steels is of critical importance for the use of the material in fuel cladding or blanket components in advanced nuclear reactors. In the present work, impact of structures of oxide dispersoids on the irradiation hardening of ODS ferritic steels was studied. Specimens of three high-Cr ODS ferritic steels containing oxide dispersoids with different number density and average size were irradiated with high-energy Ni ions at about -50 °C. The energy of the incident Ni ions was varied from 12.73 MeV to 357.86 MeV by using an energy degrader at the terminal so that a plateau of atomic displacement damage (∼0.8 dpa) was produced from the near surface to a depth of 24 μm in the specimens. A nanoindentor (in constant stiffness mode with a diamond Berkovich indenter) and a Vickers micro-hardness tester were used to measure the hardeness of the specimens. The Nix-Gao model taking account of the indentation size effect (ISE) was used to fit the hardness data. It is observed that the soft substrate effect (SSE) can be diminished substantially in the irradiated specimens due to the thick damaged regions produced by the Ni ions. A linear correlation between the nano-hardeness and the micro-hardness was found. It is observed that a higher number density of oxide dispersoids with a smaller average diameter corresponds to an increased resistance to irradiation hardening, which can be ascribed to the increased sink strength of oxides/matrix interfaces to point defects. The rate equation approach and the conventional hardening model were used to analyze the influence of defect clusters on irradiation hardening in ODS ferritic steels. The numerical estimates show that the hardening caused by the interstitial type dislocation loops follows a similar trend with the experiment data.

  2. Mathematical modeling of localized melting around graphite nodules during laser surface hardening of austempered ductile iron

    Roy, A.; Manna, I.


    An attempt has been made to mathematically predict the optimum conditions of laser surface hardening (LSH) of austempered ductile iron (ADI) that can ensure a predominantly martensitic microstructure and preclude partial/complete dissolution of graphite nodules in the laser hardened zone during laser irradiation. The exercise involves prediction of the thermal profile (using the Ashby and Easterling model), and consequently, the carbon diffusion profile around the graphite nodules at different depths from the surface for the given conditions of LSH. Microstructural investigations have been carried out by optical and scanning electron microscopy to study the morphology, shape and width of the partially/completely melted graphite nodules as a function of the LSH parameters. Finally, the predicted maximum width of the melted zone around the graphite nodules is compared with the relevant experimental data to validate the proposed model.

  3. Large Scale 3-D Dislocation Dynamics and Atomistic Simulations of Flow and Strain-Hardening Behavior of Metallic Micropillars

    Rao, Satish


    Experimental studies show strong strengthening effects for micrometer-scale FCC as well as two-phase superalloy crystals, even at high initial dislocation densities. This talk shows results from large-scale 3-D discrete dislocation simulations (DDS) used to explicitly model the deformation behavior of FCC Ni (flow stress and strain-hardening) as well as superalloy microcrystals for diameters ranging from 1 - 20 microns. The work shows that two size-sensitive athermal hardening processes, beyond forest and precipitation hardening, are sufficient to develop the dimensional scaling of the flow stress, stochastic stress variation, flow intermittency and, high initial strain-hardening rates, similar to experimental observations for various materials. In addition, 3D dislocation dynamics simulations are used to investigate strain-hardening characteristics and dislocation microstructure evolution with strain in large 20 micron size Ni microcrystals (bulk-like) under three different loading axes: 111, 001 and 110. Three different multi-slip loading axes, , and , are explored for shear strains of ~0.03 and final dislocation densities of ~1013/m2. The orientation dependence of initial strain hardening rates and dislocation microstructure evolution with strain are discussed. The simulated strain hardening results are compared with experimental data under similar loading conditions from bulk single-crystal Ni. Finally, atomistic simulation results on the operation of single arm sources in Ni bipillars with a large angle grain boundary is discussed. The atomistic simulation results are compared with experimental mechanical behavior data on Cu bipillars with a similar large angle grain boundary. This work was supported by AFOSR (Dr. David Stargel), and by a grant of computer time from the DOD High Performance Computing Modernization Program, at the Aeronautical Systems Center/Major Shared Resource Center.

  4. Associative conditioning analog selectively increases cAMP levels of tail sensory neurons in Aplysia.

    Ocorr, K A; Walters, E T; Byrne, J H


    Bilateral clusters of sensory neurons in the pleural ganglia of Aplysia contain cells involved in a defensive tail withdrawal reflex. These cells exhibit heterosynaptic facilitation in response to noxious skin stimulation that can be mimicked by the application of serotonin. Recently it has been shown that this facilitation can be selectively amplified by the application of a classical conditioning procedure to individual sensory neurons. We now report that an analog of this classical conditioning paradigm produces a selective amplification of the cAMP content of isolated sensory neuron clusters. The enhancement is achieved within a single trial and appears to be localized to the sensory neurons. These results indicate that a pairing-specific enhancement of cAMP levels may be a biochemical mechanism for associative neuronal modifications and perhaps learning.

  5. Increase of informative culture of students in the conditions of informatization of education

    Apshay N.I.


    Full Text Available The aspects of informative culture are examined in the conditions of the use of informative electronic resources. It is rotined that student plagiarism is investigation of absence of skills of treatment and processing of electronic information, domain technologies of creation of own educational texts on-line. It is thus necessary to take into account the norms of copyright. The methods of overcoming of negative displays of conduct are offered in an electronic educational environment.

  6. Glycerol and urea can be used to increase skin permeability in reduced hydration conditions.

    Björklund, Sebastian; Engblom, Johan; Thuresson, Krister; Sparr, Emma


    The natural moisturizing factor (NMF) is a group of hygroscopic molecules that is naturally present in skin and protects from severe drying. Glycerol and urea are two examples of NMF components that are also used in skin care applications. In the present study, we investigate the influence of glycerol and urea on the permeability of a model drug (metronidazole, Mz) across excised pig skin membranes at different hydrating conditions. The degree of skin hydration is regulated by the gradient in water activity across the membrane, which in turn depends on the water activity of the formulation in contact with the skin membrane. Here, we determine the water activity of all formulations employed using an isothermal calorimetric method. Thus, the gradient in water activity is controlled by a novel experimental set-up with well-defined boundary conditions on both sides of the skin membrane. The results demonstrate that glycerol and urea can retain high steady state flux of Mz across skin membranes at dehydrating conditions, which otherwise would decrease the permeability due to dehydration. X-ray diffraction measurements are performed to give insight into the effects of glycerol and urea on SC molecular organization. The novel steady state flux results can be related to the observation that water, glycerol, and urea all affect the structural features of the SC molecular components in a similar manner.

  7. Neonatal Handling Increases Cardiovascular Reactivity to Contextual Fear Conditioning in Borderline Hypertensive Rats (BHR)

    Sanders, Brian J.; Knoepfler, Jonathan


    Much research has demonstrated that events occurring in early life can have a profound influence on future biobehavioral responses to stressful and emotion provoking situations. The purpose of these studies was to determine the effects of an early environmental manipulation, handling (HAN) on cardiovascular (CV) reactivity, freezing behavior and corticosterone (CORT) responses to contextual fear conditioning in the borderline hypertensive rat (BHR), which is susceptible to environmental stressors. HAN subjects were separated from the nest for 15 min/day on post-natal days 1–14, while non-handled (NON-HAN) controls remained in the home cage. Adult subjects were exposed to the contextual fear conditioning procedure and returned to the chamber 24 h later for a 10 min test period. HAN subjects displayed significantly more freezing behavior compared to NON-HAN(92%±2.2 vs 80.7%±5.7, p handling can modulate biobehavioral responses to contextual fear conditioning in BHR and may suggest a useful model with which to study emotionality and susceptibility to CV disease. PMID:18538802

  8. Increased writing activity in neurological conditions: a review and clinical study.

    van Vugt, P; Paquier, P.; Kees, L; Cras, P.


    Increased writing activity in a 70 year old, right handed man presenting with a history of alcohol misuse and maturity onset diabetes is reported. Brain CT disclosed corticosubcortical atrophy and 99mTc-HMPAO SPECT disclosed severe bilateral frontal hypoperfusion more prominent on the right. The patient's neuropsychological symptomatology consisted of severe (verbal) aspontaneity, intermittent utilisation behaviour, and pronounced increased writing activity, which mainly consisted of a persev...

  9. Environmental hardening of robots for nuclear maintenance and surveillance tasks

    Hintenlang, D.E.; Tulenko, J.S.; Wheeler, R.; Roy, T. (Univ. of Florida, Gainesville (USA))


    The University of Florida, in cooperation with the Universities of Texas, Tennessee, and Michigan and Oak Ridge National Laboratory, is developing an advanced robotic system for the US Department of Energy under the University Program for Robotics for Advanced Reactors. As part of this program, the University of Florida has been pursuing the development of environmentally hardened components so that autonomous robotic systems can successfully carry out their tasks under the most extreme expected environmental conditions. This requirement means that the designed robotic system with its onboard computer-based intelligence must be able to successfully complete tasks in toxic, radioactive, wet, temperature extremes, and other physically impairing environments. As part of this program, a study was carried out to determine the environmental conditions that should be set as the design criteria for robotic systems to maintain reasonable operations for nuclear plants in the course of maintenance, testing, and surveillance under all conditions, including plant upset. It was decided that Florida would build a combined environmental testing facility to test specific devices in high-radiation/high-temperature combined environments. This environmental test chamber has been built and successfully tested to over 250{degree}F. This facility will provide some of the first combined temperatures/radiation data for many large-scale integrated components.

  10. Normal Maternal Behavior, But Increased Pup Mortality, in Conditional Oxytocin Receptor Knockout Females

    Macbeth, Abbe H.; Stepp, Jennifer E.; Lee, Heon-Jin; Young, W. Scott; Caldwell, Heather K.


    Oxytocin (Oxt) and the Oxt receptor (Oxtr) are implicated in the onset of maternal behavior in a variety of species. Recently, we developed two Oxtr knockout lines: a total body knockout (Oxtr−/−) and a conditional Oxtr knockout (OxtrFB/FB) in which the Oxtr is lacking only in regions of the forebrain, allowing knockout females to potentially nurse and care for their biological offspring. In the current study, we assessed maternal behavior of postpartum OxtrFB/FB females toward their own pups...

  11. Tailored work hardening descriptions in simulation of sheet metal forming

    Vegter, Henk; Mulder, Hans.; van Liempt, Peter; Heijne, Jan


    In the previous decades much attention has been given on an accurate material description, especially for simulations at the design stage of new models in the automotive industry. Improvements lead to shorter design times and a better tailored use of material. It also contributed to the design and optimization of new materials. The current description of plastic material behaviour in simulation models of sheet metal forming is covered by a hardening curve and a yield surface. In this paper the focus will be on modelling of work hardening for advanced high strength steels considering the requirements of present applications. Nowadays work hardening models need to include the effect of hard phases in a soft matrix and the effect of strain rate and temperature on work hardening. Most material tests to characterize work hardening are only applicable to low strains whereas many practical applications require hardening data at relatively high strains. Therefore, physically based hardening descriptions are needed allowing reliable extensions to high strain values.

  12. Press-hardening of zinc coated steel - characterization of a new material for a new process

    Kurz, T.; Larour, P.; Lackner, J.; Steck, T.; Jesner, G.


    Press-hardening of zinc-coated PHS has been limited to the indirect process until a pre-cooling step was introduced before the hot forming to prevent liquid metal embrittlement. Even though that's only a minor change in the process itself it does not only eliminate LME, but increases also the demands on the base material especially in terms of hardenability or phase transformations at temperatures below 700 °C in general. This paper deals with the characterization of a modified zinc-coated material for press-hardening with pre-cooling that assures a robust process. The pre-cooling step itself and especially the transfer of the blank in the hot-forming die is more demanding than the standard 22MnB5 can stand to ensure full hardenability. Therefore the transformation behavior of the modified material is shown in CCT and TTT diagrams. Of the same importance are the changed hot forming temperature and flow curves for material at lower temperatures than typically used in direct hot forming. The resulting mechanical properties after hardening from tensile testing and bending tests are shown in detail. Finally some results from side impact crash tests and correlations of the findings with mechanical properties such as fracture elongation, tensile strength, VDA238 bending angle at maximum force as well as postuniform bending slope are given as well. Fracture elongation is shown to be of little help for damage prediction in side impact crash. Tensile strength and VDA bending properties enable however some accurate prediction of the PHS final damage behavior in bending dominated side impact load case.

  13. Conservation Research and Development/ New Ultra-Low Carbon High Strength Steels with Improved Bake Hardenability for Enhanced Stretch Formability and Dent Resistance

    Anthony J. DeArdo; C. Isaac Garcia


    Conservation Research and Development/New Ultra-Low Carbon High Strength Steels with Improved Bake Hardenability for Enhanced Stretch Formability and Dent Resistance. The experimental work can be divided into four phases. In each phase, the materials were received or designed, processed and tested, to evaluate the BH increment or response, as a function of compositions and processing conditions. Microstructural characterization by various techniques was performed in order to gain insights into the mechanisms of flow stress increment by bake hardening.

  14. Achieving large macroscopic compressive plastic deformation and work-hardening-like behavior in a monolithic bulk metallic glass by tailoring stress distribution

    Chen, L. Y.; Ge, Q.; Qu, S.; Jiang, Q. K.; Nie, X. P.; Jiang, J. Z.


    The limited plastic deformation and lack of work hardening seriously restrict the applications of bulk metallic glasses (BMGs). Here, large macroscopic compressive plastic deformation (over 15%) and work-hardening-like behavior were achieved in a monolithic BMG through tailoring loading stress distribution experimentally. Numerical analysis was also carried out to investigate the stress distribution under the same mechanical condition. It is shown that loading induced stress gradient is responsible for the achievement mentioned above.


    LIUTeng-xi; HUANGShi-qing; FUYi-ming


    A dimensionless stress yield criterion is proposed to describe the mixed hardening of orthortropic material ,including kinematic hardening and proportional hardening,and the associated plastic flow law is derived.The generalized effective stress-strain formulae can be obtained correspondingly based on the experimental stress-strain curves in various simple stress states.The initial plastic anisotropy is influenced by the elastic anisotropy.The yield criterion can be reduced to Huber-Mises Criterion for isotropic materials and associated constitutive equations can be degenerated into Prandtl-Reuss equations.


    刘腾喜; 黄世清; 傅衣铭


    A dimensionless stress yield criterion is proposed to describe the mixed hardening of orthotropic material, including kinematic hardening and proportional hardening, and the associated plastic flow law is derived. The generalized effective stress-strain formulae can be obtained correspondingly based on the experimental stress-strain curves in various simple stress states. The initial plastic anisotropy is influenced by the elastic anisotropy. The yield criterion can be reduced to Huber-Mises Criterion for isotropic materials and associated constitutive equations can be degenerated into Prandtl-Reuss equations.

  17. Variations in the Bainite Hardenability of ASTM A723 Steel


    8217, ,- -’ . . • • . . . . -. . " . ,~ .. -- --. x n~ I]AD TECHNICAL REPORT ARCCB-TR-87012 VARIATIONS IN THE BAINITE U) HARDENABILITY OF ASTM A723 STEEL 0’) 00 PAUL J. COTE LAWRENCE V...rod ,SuDfll|m) S. ?YPl[ Off REPOR.r & Pl[RIOO COVER•O VARIATIONS IN THE; BAINITE HARDENABILITY OF Final ASTH A723 STEEL I. Pl[RFORMINQ ORO. REPORT...0.1%) and copper (0.1%) in A723. A key transformation characteristic for this alloy is the bainite hardenability. It is important to know the extent to

  18. Influence of time of annealing on anneal hardening effect of a cast CuZn alloy

    Nestorović Svetlana


    Full Text Available Investigated cast copper alloy containing 8at%Zn of a solute. For comparison parallel specimens made from cast pure copper. Copper and copper alloy were subjected to cold rolling with different a final reduction of 30,50 and 70%. The cold rolled copper and copper alloy samples were isochronally and isothermally annealed up to recrystallization temperature. After that the values of hardness, strength and electrical conductivity were measured and X-ray analysis was performed. These investigations show that anneal hardening effect at alloys was attained under recrystallization temperature in the temperature range of 180-3000C, followed with an increase in hardness. The amount of strengthening increase with increasing degree of prior cold work. Also the X-ray analysis show the change of lattice parameter during annealing when anneal hardening effect was attained.

  19. Influence of degree of deformation in rolling on anneal hardening effect of a cast copper alloy

    Svetlana Nestorovic; Desimir Markovic; Ljubica Ivanic


    This paper reports results of investigations carried out on a cast copper alloy containing 8 at.% Al. The alloy, and pure copper for the sake of comparison, were subjected to cold rolling with a final reduction of 30, 50 or 70%. The cold rolled copper and copper alloy samples were isochronally and isothermally annealed up to the recrystallization temperature. The hardness, strength and electrical conductivity were measured and X-ray and DSC analyses performed. Anneal hardening effect was observed in the alloy in the temperature range 180–300°C, followed by an increase in the electrical conductivity. The amount of strengthening increases with increasing degree of prior cold work. The X-ray analysis shows a change in the lattice parameter during annealing when anneal hardening effect was observed. The DSC analysis shows the exothermic character of this effect.

  20. Increase of plasma renin activity in male and female rabbits subjected to dysbaric conditions

    Chryssanthou, C.; Kircikoglu, H.; Strugar, J.


    The renin-angiotensin-aldosterone system may be implicated in hemodynamic alterations occurring in dysbaric disorders. This report concerns changes in plasma renin activity (PRA) induced by exposure of rabbits to a compression-decompression schedule that does not normally produce clinical manifestations of decompression sickness. The results revealed a significant increase in PRA in 19 of 23 animals following dysbaric exposure. Mean PRA rose from 1.18 ng ang I/ml hr (preexposure) to 2.40 ng ang I/ml hr (postexposure). The increase was particularly pronounced in female animals (217 percent). Asymptomatic intravascular gas bubbles (silent bubbles) were detected by gross or microscopic examination in the majority of the animals. Renin elaboration and secretion in asymptomatic dysbaric exposures may be mediated by bradykinin and/or prostaglandins released or activated in a chain reaction triggered by silent gas bubbles. This hypothesis is also applicable to increased PRA in altitude decompression. Alternatively elevation of PRA may result from decreased renal perfusion when dysbaric disorders are complicated by significant hypovolemia.

  1. Human Serum Albumin Increases the Stability of Green Tea Catechins in Aqueous Physiological Conditions.

    Angelo Zinellu

    Full Text Available Epicatechin (EC, epigallocatechin (EGC, epicatechingallate (ECG and epigallocatechingallate (EGCG are antioxidants present in the green tea, a widely used beverage whose health benefits are largely recognized. Nevertheless, major physicochemical limitations, such as the high instability of catechins, pose important questions concerning their potential pharmacological use. Recent studies indicate that binding of catechins with plasmatic proteins may modulate their plasma concentration, tissue delivery and biological activity. After 5 minutes of incubation with HSA both ECG and EGCG were fully bound to HSA, while after 48h incubation only 41% of EC and 70% of EGC resulted linked. HSA had a strong stabilizing effect on all catechins, which could be found in solution between 29 and 85% even after 48h of incubation. In the absence of HSA, EGC and EGCG disappeared in less than 24h, while ECG and EC were found after 48h at 5 and 50%, respectively. The stabilizing effect of HSA toward EGCG, obtained in aqueous physiological conditions, resulted stronger in comparison to cysteine and HCl, previously reported to stabilize this polyphenol. Because of the multitude of contradictory data concerning in vivo and in vitro antioxidant-based experimentations, we believe our work may shed some light on this debated field of research.

  2. Human Serum Albumin Increases the Stability of Green Tea Catechins in Aqueous Physiological Conditions.

    Zinellu, Angelo; Sotgia, Salvatore; Scanu, Bastianina; Forteschi, Mauro; Giordo, Roberta; Cossu, Annalisa; Posadino, Anna Maria; Carru, Ciriaco; Pintus, Gianfranco


    Epicatechin (EC), epigallocatechin (EGC), epicatechingallate (ECG) and epigallocatechingallate (EGCG) are antioxidants present in the green tea, a widely used beverage whose health benefits are largely recognized. Nevertheless, major physicochemical limitations, such as the high instability of catechins, pose important questions concerning their potential pharmacological use. Recent studies indicate that binding of catechins with plasmatic proteins may modulate their plasma concentration, tissue delivery and biological activity. After 5 minutes of incubation with HSA both ECG and EGCG were fully bound to HSA, while after 48h incubation only 41% of EC and 70% of EGC resulted linked. HSA had a strong stabilizing effect on all catechins, which could be found in solution between 29 and 85% even after 48h of incubation. In the absence of HSA, EGC and EGCG disappeared in less than 24h, while ECG and EC were found after 48h at 5 and 50%, respectively. The stabilizing effect of HSA toward EGCG, obtained in aqueous physiological conditions, resulted stronger in comparison to cysteine and HCl, previously reported to stabilize this polyphenol. Because of the multitude of contradictory data concerning in vivo and in vitro antioxidant-based experimentations, we believe our work may shed some light on this debated field of research.

  3. Normal maternal behavior, but increased pup mortality, in conditional oxytocin receptor knockout females.

    Macbeth, Abbe H; Stepp, Jennifer E; Lee, Heon-Jin; Young, W Scott; Caldwell, Heather K


    Oxytocin (Oxt) and the Oxt receptor (Oxtr) are implicated in the onset of maternal behavior in a variety of species. Recently, we developed two Oxtr knockout lines: a total body knockout (Oxtr-/-) and a conditional Oxtr knockout (OxtrFB/FB) in which the Oxtr is lacking only in regions of the forebrain, allowing knockout females to potentially nurse and care for their biological offspring. In the current study, we assessed maternal behavior of postpartum OxtrFB/FB females toward their own pups and maternal behavior of virgin Oxtr-/- females toward foster pups and compared knockouts of both lines to wildtype (Oxtr+/+) littermates. We found that both Oxtr-/- and OxtrFB/FB females appear to have largely normal maternal behaviors. However, with first litters, approximately 40% of the OxtrFB/FB knockout dams experienced high pup mortality, compared to fewer than 10% of the Oxtr+/+ dams. We then went on to test whether or not this phenotype occurred in subsequent litters or when the dams were exposed to an environmental disturbance. We found that regardless of the degree of external disturbance, OxtrFB/FB females lost more pups on their first and second litters compared to wildtype females. Possible reasons for higher pup mortality in OxtrFB/FB females are discussed.

  4. Dexmedetomidine Increases Tau Phosphorylation Under Normothermic Conditions In Vivo and In Vitro

    Whittington, Robert A.; Virág, László; Gratuze, Maud; Petry, Franck R.; Noël, Anastasia; Poitras, Isabelle; Truchetti, Geoffrey; Marcouiller, François; Papon, Marie-Amélie; Khoury, Noura El; Wong, Kevin; Bretteville, Alexis; Morin, Françoise; Planel, Emmanuel


    There is developing interest in the potential association between anesthesia and the onset and progression of Alzheimer's disease. Several anesthetics have thus been demonstrated to induce tau hyperphosphorylation, an effect mostly mediated by anesthesia-induced hypothermia. Here, we tested the hypothesis that acute normothermic administration of dexmedetomidine, an intravenous sedative used in intensive care units, would result in tau hyperphosphorylation in vivo and in vitro. When administered to non-transgenic mice, dexmedetomidine induced tau hyperphosphorylation persisting up to 6h in the hippocampus for the AT8 epitope. Pretreatment with atipamezole, a highly specific α2-adrenergic receptor (α2-AR) antagonist, blocked dexmedetomidine-induced tau hyperphosphorylation. Furthermore, dexmedetomidine dose-dependently increased tau phosphorylation at AT8 in SH-SY5Y cells, impaired mice spatial memory in the Barnes maze, and promoted tau hyperphosphorylation and aggregation in transgenic hTau mice. These findings suggest that dexmedetomidine: i) increases tau phosphorylation, in vivo and in vitro, in the absence of anesthetic-induced hypothermia and through α2-AR activation, ii) promotes tau aggregation in a mouse model of tauopathy, and iii) impacts spatial reference memory. PMID:26058840

  5. A Study of Effects of Precipitation Hardening of Low-Alloy Copper-Nickel Spheroidal Cast Iron

    Szykowny T.


    Full Text Available One type of spheroidal cast iron, with additions of 0.51% Cu and 0.72% Ni, was subjected to precipitation hardening. Assuming that the greatest increase in hardness after the shortest time of ageing is facilitated by chemical homogenisation and fragmentation of cast iron grain matrix, precipitation hardening after pre-normalisation was executed. Hardness (HB, microhardness (HV, qualitative and quantitative metalographic (LM, SEM and X-ray structural (XRD tests were performed. The acquired result of 13.2% increase in hardness after ca. 5-hour ageing of pre-normalised cast iron confirmed the assumption.

  6. 21st century increases in the likelihood of extreme hydrologic conditions for the mountainous basins of the Southwestern United States

    Stewart, Iris T.; Ficklin, Darren L.; Carrillo, Carlos A.; McIntosh, Russell


    Extreme hydrologic conditions, such as floods, droughts, and elevated stream temperatures, significantly impact the societal fabric and ecosystems, and there is rising concern about increases in the frequency of extreme conditions with projected climate changes. Here we ask what changes in the occurrence of extreme hydrologic conditions can be expected by the end of the century for the important water-generating, mountainous basins of the Southwestern United States, namely the Sierra Nevada and Upper Colorado River Basins. The extreme conditions considered are very high flows, low flows, and elevated stream temperature as derived from historic and future simulations using the Soil and Water Assessment Tool (SWAT) hydrologic model and downscaled output from a General Circulation Model ensemble. Results indicate noteworthy differences in the frequency changes of extremes based on geographic region, season, elevation, and stream size. We found wide-spread increases in the occurrence of stream flows exceeding 150% of historic monthly averages for winter by the end of the century, and extensive increases in the occurrence of both extreme low flows (representing 3 °C of monthly averages) during the summer months, with some basins expecting extreme conditions 90-100% of the time by the end of the century. Understanding the differences in the changes of extreme conditions can identify climate-sensitive regions and assist in targeted planning for climate change adaptation and mitigation.

  7. Predicting of mechanical properties of EN AB-46000 alloy subjected to dispersion hardening

    J. Pezda


    Full Text Available Improvement of silumin properties in range of classic methods involves change of morphology of silicon precipitation through: modification treatment of the alloy, maintaining suitable temperature when superheating and pouring into moulds, as well as perfection of heat treatment processes. Dispersion hardening with holding of the alloy in temperature near to temperature of solidus, consisting in heating of poured specimens up to temperature of solutioning, holding the specimens in such temperature, and next cooling down in cold water (20 0C and next artificial ageing, what have effect on change of mechanical properties of EN AB-46000 alloy, while selection of suitable parameters of dispersion hardening treatment is a condition of obtainment of positive effects in form of improved mechanical properties. Obtained dependencies enable determination of mechanical properties of the investigated alloy before commencing of solutioning and ageing treatments.

  8. Deformation behavior in reactor pressure vessel steels as a clue to understanding irradiation hardening.

    DiMelfi, R. J.; Alexander, D. E.; Rehn, L. E.


    In this paper, we examine the post-yield true stress vs true strain behavior of irradiated pressure vessel steels and iron-based alloys to reveal differences in strain-hardening behavior associated with different irradiating particles (neutrons and electrons) and different alloy chernky. It is important to understand the effects on mechanical properties caused by displacement producing radiation of nuclear reactor pressure steels. Critical embrittling effects, e.g. increases in the ductile-to-brittle-transition-temperature, are associated with irradiation-induced increases in yield strength. In addition, fatigue-life and loading-rate effects on fracture can be related to the post-irradiation strain-hardening behavior of the steels. All of these properties affect the expected service life of nuclear reactor pressure vessels. We address the characteristics of two general strengthening effects that we believe are relevant to the differing defect cluster characters produced by neutrons and electrons in four different alloys: two pressure vessel steels, A212B and A350, and two binary alloys, Fe-0.28 wt%Cu and Fe-0.74 wt%Ni. Our results show that there are differences in the post-irradiation mechanical behavior for the two kinds of irradiation and that the differences are related both to differences in damage produced and alloy chemistry. We find that while electron and neutron irradiations (at T {le} 60 C) of pressure vessel steels and binary iron-based model alloys produce similar increases in yield strength for the same dose level, they do not result in the same post-yield hardening behavior. For neutron irradiation, the true stress flow curves of the irradiated material can be made to superimpose on that of the unirradiated material, when the former are shifted appropriately along the strain axis. This behavior suggests that neutron irradiation hardening has the same effect as strain hardening for all of the materials analyzed. For electron irradiated steels, the

  9. Space Qualified, Radiation Hardened, Dense Monolithic Flash Memory Project

    National Aeronautics and Space Administration — Space Micro proposes to build a radiation hardened by design (RHBD) flash memory, using a modified version of our RH-eDRAM Memory Controller to solve all the single...

  10. Space Qualified, Radiation Hardened, Dense Monolithic Flash Memory Project

    National Aeronautics and Space Administration — Radiation hardened nonvolatile memories for space is still primarily confined to EEPROM. There is high density effective or cost effective NVM solution available to...

  11. Radiation Hardened Ethernet PHY and Switch Fabric Project

    National Aeronautics and Space Administration — Innoflight will develop a new family of radiation hardened (up to 3 Mrad(Si)), fault-tolerant, high data-rate (up to 8 Gbps), low power Gigabit Ethernet PHY and...

  12. Technologies Enabling Custom Radiation-Hardened Component Development Project

    National Aeronautics and Space Administration — Two primary paths are available for the creation of a Rad-Hard ASIC. The first approach is to use a radiation hardened process such as existing Rad-Hard foundries....

  13. Novel SEU hardened PD SOI SRAM cell

    Xie Chengmin; Wang Zhongfang; Wang Xihu; Wu Longsheng; Liu Youbao


    A novel SEU hardened 10T PD SOI SRAM cell is proposed.By dividing each pull-up and pull-down transistor in the cross-coupled inverters into two cascaded transistors,this cell suppresses the parasitic BJT and source-drain penetration charge collection effect in PD SOl transistor which causes the SEU in PD SOI SRAM.Mixed-mode simulation shows that this novel cell completely solves the SEU,where the ion affects the single transistor.Through analysis of the upset mechanism of this novel cell,SEU performance is roughly equal to the multiple-cell upset performance of a normal 6T SOI SRAM and it is thought that the SEU performance is 17 times greater than traditional 6T SRAM in 45nm PD SOI technology node based on the tested data of the references.To achieve this,the new cell adds four transistors and has a 43.4% area overhead and performance penalty.

  14. Cylindrical shell buckling through strain hardening

    Bandyopadhyay, K.; Xu, J.; Shteyngart, S. [Brookhaven National Lab., Upton, NY (United States); Gupta, D. [USDOE, Germantown, MD (United States)


    Recently, the authors published results of plastic buckling analysis of cylindrical shells. Ideal elastic-plastic material behavior was used for the analysis. Subsequently, the buckling analysis program was continued with the realistic stress-strain relationship of a stainless steel alloy which does not exhibit a clear yield point. The plastic buckling analysis was carried out through the initial stages of strain hardening for various internal pressure values. The computer program BOSOR5 was used for this purpose. Results were compared with those obtained from the idealized elastic-plastic relationship using the offset stress level at 0.2% strain as the yield stress. For moderate hoop stress values, the realistic stress-grain case shows a slight reduction of the buckling strength. But, a substantial gain in the buckling strength is observed as the hoop stress approaches the yield strength. Most importantly, the shell retains a residual strength to carry a small amount of axial compressive load even when the hoop stress has exceeded the offset yield strength.

  15. Progressive Increase in Telomerase Activity From Benign Melanocytic Conditions to Malignant Melanoma

    Ruben D. Ramirez


    Full Text Available The expression of telomerase activity and the in situ localization of the human telomerase RNA component (hTR in melanocytic skin lesions was evaluated in specimens from sixty-three patients. Specimens of melanocytic nevi, primary melanomas and subcutaneous metastases of melanoma were obtained from fifty-eight patients, whereas metastasized lymph nodes were obtained from five patients. Telomerase activity was determined in these specimens by using a Polymerase Chain Reaction—based assay (TRAP. High relative mean telomerase activity levels were detected in metastatic melanoma (subcutaneous metastasess = 54.5, lymph node metastasess = 56.5. Much lower levels were detected in primary melanomas, which increased with advancing levels of tumor cell penetration (Clark II = 0.02, Clark III = 1.1, and Clark IV = 1.9. Twenty-six formalin-fixed, paraffin-embedded melanocytic lesions were sectioned and analyzed for telomerase RNA with a radioactive in situ hybridization assay. In situ hybridization studies with a probe to the template RNA component of telomerase confirmed that expression was almost exclusively confined to tumor cells and not infiltrating lymphocytes. These results indicate that levels of telomerase activity and telomerase RNA in melanocytic lesions correlate well with clinical stage and could potentially assist in the diagnosis of borderline lesions.

  16. Crystallization and hardening of poly(ethylene-co-vinyl acetate) mouthguards during routine use

    Kuwahara, Ryoko; Tomita, Ryotaro; Ogawa, Natsumi; Nakajima, Kazunori; Takeda, Tomotaka; Uehara, Hiroki; Yamanobe, Takeshi


    Mouthguards (MGs) made from poly(ethylene-co-vinyl acetate) (EVA) are widely used in contact sports to prevent injuries such as breaking teeth and lip lacerations and to reduce brain concussion. However, the changes in morphology and the molecular mobility of EVA, which can affect its physical properties during practical usage, have not been precisely examined. Therefore, we attempted to determine the main factors which lead to changes in MG performance after one season of practical use by high school rugby players. Solid-state nuclear magnetic resonance (NMR) and pulse NMR measurements showed the hardening of MGs, which was associated with an increased crystallinity of the EVA resulting from prolonged usage. Furthermore, our data indicated that the increase in the relative amount of the crystalline phase may be primarily attributed to temperature fluctuations and repeated changes in pressure, which could cause the hardening of EVA and eventually diminish the protective ability of MGs. PMID:28294184

  17. Embrittlernent of irradiated F82H in the absence of irradiation hardening

    Klueh, Ronald L [ORNL; Shiba, Kiyoyuki [ORNL; Sokolov, Mikhail A [ORNL


    Neutron irradiation of 7-12% Cr ferritic/martensitic steels below 425-450 C produces microstructural defects and precipitation that cause an increase in yield stress. This irradiation hardening causes embrittlement, which is observed in a Charpy impact or fracture toughness test as an increase in the ductile-brittle transition temperature. Based on observations that show little change in strength in steels irradiated above 425-450 C, the general conclusion has been that no embrittlement occurs above these temperatures. In a recent study of F82H steel, significant embrittlement was observed after irradiation at 500 C. This embrittlement is apparently due to irradiation-accelerated Laves-phase precipitation. Observations of the embrittlement in the absence of hardening has been examined and analyzed with thermal-aging studies and computational thermodynamics calculations to illuminate and understand the effect.

  18. A procedure for hardening steel 45 by plastic deformation using a simple roller

    Tomás Fernández Columbíe


    Full Text Available This work presents the techniques used in an experimental design leading to evaluating the behaviour of an indepen-dent variable force (P, ranging from 500 up to 2500 N, 27 minimum revolution number (n, average 54 and maxi-mum 110 rev/min and 0.075, 0, 125 and 0.25 mm/rev advance for determining the dependent hardness (H pa-ttern when AISI 1045 steel test tubes were subjected to surface rolling for creating a compressive state deforming and increasing its resistance to abrasive wear and fatigue. The variables involved in the process were statistically a-nalysed, revealing increased hardness ranging from 220 up to 262 HV. Optical microscopy was used for analysing the effect of hardening caused by deformation, establishing a mechanism for hardening steel by the elements in the crystalline network sliding due to burnishing.

  19. Crystallization and hardening of poly(ethylene-co-vinyl acetate) mouthguards during routine use.

    Kuwahara, Ryoko; Tomita, Ryotaro; Ogawa, Natsumi; Nakajima, Kazunori; Takeda, Tomotaka; Uehara, Hiroki; Yamanobe, Takeshi


    Mouthguards (MGs) made from poly(ethylene-co-vinyl acetate) (EVA) are widely used in contact sports to prevent injuries such as breaking teeth and lip lacerations and to reduce brain concussion. However, the changes in morphology and the molecular mobility of EVA, which can affect its physical properties during practical usage, have not been precisely examined. Therefore, we attempted to determine the main factors which lead to changes in MG performance after one season of practical use by high school rugby players. Solid-state nuclear magnetic resonance (NMR) and pulse NMR measurements showed the hardening of MGs, which was associated with an increased crystallinity of the EVA resulting from prolonged usage. Furthermore, our data indicated that the increase in the relative amount of the crystalline phase may be primarily attributed to temperature fluctuations and repeated changes in pressure, which could cause the hardening of EVA and eventually diminish the protective ability of MGs.

  20. Radiation effects in power converters: Design of a radiation hardened integrated switching DC/DC converter

    Adell, Philippe

    When electronic devices are used in space and military systems, they may be exposed to various types of radiation, including photons, electrons, protons, neutrons, and heavy ions. The effects of radiation on the semiconductor devices within the systems range from gradual degradation to catastrophic failure. In order to design and produce reliable systems for space or military applications, it is necessary to understand the device-level effects of radiation and develop appropriate strategies for reducing system susceptibility. This research focuses on understanding radiation effects in power converters for space and military applications. We show that power converters are very sensitive to radiation (total-dose, single event effects and displacement damage) and that their radiation response is dependent on input bias conditions and load conditions. We compared the radiation hardness of various power converter topologies using experiments and simulations. Evaluation of these designs under different modes of operation is demonstrated to be critical for determining radiation hardness. We emphasize the correlation between radiation effects and the role of the dynamic response of these topologies. For instance, total dose exposure has been found to degrade loop gain and affect regulation in some converters. We propose several radiation-hardening solutions to improve the radiation response of these designs. For instance, we demonstrate the design of a digitally controlled boost converter suitable for space applications based on an SRAM FPGA. A design hardening solution has been developed and successfully applied through VHDL simulations and experiments to assure the continuous operation of the converter in the presence of SEES (more precisely SEFIs). This research led to the design of a digitally controlled radiation hardened integrated switching buck converter. The proposed design is suitable for micro-satellite applications and is based on a high-voltage/CMOS process

  1. Hardening in Two-Phase Materials. II. Plastic Strain and Mean Stress Hardening Rate

    Lilholt, Hans


    The strain parameters which are relevant in a tensile experiment, are analysed and related to the geometry of deformation and to the mean stress of two-phase materials. The hardening rate of the mean stress with respect to plastic strain is found to be useful in comparison between experiments and...... and theories, and it allows theories to be probed over a range of strains. Previous experiments on the fibre-reinforced material of copper-tungsten are analysed in relation to the geometry of deformation....

  2. Mechanisms of age-hardening in two Al-Cu-Mg alloys studied by positron annihilation spectroscopy

    Ferragut, R. [Univ. Nacional del Centro de la Provincia de Buenos Aires, Tandil (Argentina). IFIMAT; INFM and Dipt. di Fisica, Politecnico di Milano, Milano (Italy); Somoza, A. [Univ. Nacional del Centro de la Provincia de Buenos Aires, Tandil (Argentina). IFIMAT; Dupasquier, A. [INFM and Dipt. di Fisica, Politecnico di Milano, Milano (Italy); Polmear, I.J. [Monash Univ., School of Physics and Materials Engineering, Melbourne (Australia)


    Age-hardening at 150 C has been studied in an Al-Cu-Mg alloy microalloyed with 0.1 at.% Ag and the commercial alloy 2024. Positron annihilation lifetime spectroscopy (PALS) was combined with measurements of microhardness changes during ageing at 150 C. Both alloys are known to harden in two stages separated by an extended plateau. Combined PALS and hardness data shows that the effect of Ag is to enhance vacancy trapping at Mg atoms in competition with the formation of mobile vacancy-Cu pairs. Thus, the addition of Ag gives a reduction of Cu atoms mobility, leading to slower initial hardening in comparison with a silver-free alloy with similar Cu:Mg ratio. In both alloys, the second stage of hardening begins before increases occur in positron lifetimes that indicate the formation of misfit interfaces (i.e. semi-coherent precipitates). This observation supports the view that this second stage of hardening in alloys based on the Al-Cu-Mg system is associated mainly with the growth and transformation of coherent GP(Cu,Mg) zones. The PALS data are consistent with the hypothesis that the X' phase, previously observed to be present in Al-Cu-Mg-Ag at peak ageing, develops misfit interfaces with the matrix. (orig.)

  3. Anomalous temperature dependence of yield stress and work hardening coefficient of B2-stabilized NiTi alloys

    Hosoda, Hideki; Mishima, Yoshinao [Tokyo Inst. of Tech., Yokohama (Japan). Precision and Intelligence Lab.; Suzuki, Tomoo [Tokyo Inst. of Tech. (Japan)


    Yield stress and work hardening coefficient of B2-stabilized NiTi alloys are investigated using compression tests. Compositions of NiTi alloys are based on Ni-49mol.%Ti, to which Cr, Co and Al are chosen as ternary elements which reduce martensitic transformation temperatures of the B2 phase. Mechanical tests are carried out in liquid nitrogen at 77 K, air at room temperature (R.T.) and in an argon atmosphere between 473 K and 873 K. Only at 77 K, some alloys show characteristic stress-strain curves which indicate stress induced martensitic transformation (SIMT), but the others do not. Work hardening coefficient is found to be between 2 and 11GPa in all the test temperature range. The values are extremely high compared with Young`s modulus of B2 NiTi. Yield stress and work hardening coefficient increase with test temperature between R.T. and about 650 K in most alloys. The anomalous temperature dependence of mechanical properties is not related to SIMT but to precipitation hardening and/or anomalous dislocation motion similar to B2-type CoTi. Solution hardening by adding ternary elements is evaluated to be small for Cr and Co additions, and large for Al addition, depending on difference in atomic size of the ternary element with respect to Ni or Ti.

  4. Increased skin conductance responses and neural activity during fear conditioning are associated with a repressive coping style

    Tim eKlucken


    Full Text Available The investigation of individual differences in coping styles in response to fear conditioning is an important issue for a better understanding of the etiology and treatment of psychiatric disorders. It has been assumed that an avoidant (repressive coping style is characterized by increased emotion regulation efforts in context of fearful stimuli as compared to a more vigilant coping style. However, no study so far has investigated the neural correlates of fear conditioning of repressors and sensitizers.In the present fMRI study, 76 participants were classified as repressors or as sensitizers and were exposed to a fear conditioning paradigm, in which the CS+ predicted electrical stimulation, while another neutral stimulus (CS- did not. In addition, skin conductance responses (SCRs were measured continuously.As the main findings, we found increased neural activations in repressors as compared to sensitizers in the ventromedial prefrontal cortex and the anterior cingulate cortex during fear conditioning. In addition, elevated activity to the CS+ in amygdala, insula, occipital, and orbitofrontal cortex as well as conditioned SCRs were found in repressors.The present results demonstrate increased neural activations in structures linked to emotion down-regulation mechanisms like the ventromedial prefrontal cortex, which may reflect the increased coping effort in repressors. At the same time, repressors showed increased activations in arousal and evaluation-associated structures like the amygdala, the occipital cortex, and the orbitofrontal cortex, which is also mirrored in increased SCRs. The present results support recent assumptions about a two-process model of repression postulating a fast vigilant response to fearful stimuli, but also a second emotion down-regulating process.

  5. Softening of monthly cigarette use in youth and the need to harden measures in surveillance

    Lynn T. Kozlowski


    Conclusion: Additional measures of frequency and intensity of use of cigarettes and other tobacco/nicotine products need to be more regularly reported. These results indicate softening rather than hardening of “current smoking” and have important implications for tobacco surveillance and for tobacco research because of a increased likelihood of quitting smoking, b health effects of cigarette smoking, and c similar and interacting issues related to measuring the use of all tobacco/nicotine products.

  6. Mechanisms of Nutrition Bar Hardening: Effect of Hydrolyzed Whey Protein and Carbohydrate Source

    Adams, Shaun P


    The influence of increasing hydrolyzed protein content on the microstructure and hardness of high protein nutrition bars was investigated to determine the mechanism of hardening during storage. Bars with various hydrolyzed protein levels were manufactured using differing ratios of 0, 25, 50, 75, 100% (wt. /wt.) of partially hydrolyzed whey protein isolate (HWPI) to an intact (non-hydrolyzed) whey protein isolate (WPI) which made up approximately 38% of the total bar composition. High fructo...

  7. Simulation of irradiation hardening of Zircaloy within plate-type dispersion nuclear fuel elements

    Jiang, Yijie; Wang, Qiming; Cui, Yi; Huo, Yongzhong; Ding, Shurong


    Within plate-type dispersion nuclear fuel elements, the metal matrix and cladding attacked continuously by fast neutrons undergo irradiation hardening, which might have remarkable effects upon the mechanical behaviors within fuel elements. In this paper, with the irradiation hardening effect of metal materials mainly considered together with irradiation growth effect of the cladding, the three-dimensional large-deformation constitutive relations for the metal matrix and cladding are developed. The method of virtual temperature increase in the previous studies is further developed to model the irradiation swelling of fuel particles; the method of anisotropic thermal expansion is introduced to model irradiation growth of the cladding; and a method of multi-step-temperature loading is proposed to simulate the coupling features of irradiation-induced swelling of the fuel particles together with irradiation growth of the cladding. Above all, based on the developed relationship between irradiation growth at certain burnup and the loaded virtual temperatures, with considering that certain burnup corresponds to certain fast neutron fluence, the time-dependent constitutive relation due to irradiation hardening effect is replaced by the virtual-temperature-dependent one which is introduced into the commercial software to simulate the irradiation hardening effects of the matrix and cladding. Numerical simulations of the irradiation-induced mechanical behaviors are implemented with the finite element method in consideration of the micro-structure of the fuel meat. The obtained results indicate that when the irradiation hardening effects are introduced into the constitutive relations of the metal matrix and cladding: (1) higher maximum Mises stresses for certain burnup at the matrix exist with the equivalent plastic strains remaining almost the same at lower burnups; (2) the maximum Mises stresses for certain burnup at the cladding are enhanced while the maximum equivalent

  8. conditions

    M. Venkatesulu


    Full Text Available Solutions of initial value problems associated with a pair of ordinary differential systems (L1,L2 defined on two adjacent intervals I1 and I2 and satisfying certain interface-spatial conditions at the common end (interface point are studied.


    尤晓东; 何宁; 王子霖


    预加工状态的高速钢产品,在经过切削加工后,表面会产生加工硬化,影响后续加工使用。研究了高速钢M2和M2 Al两个材质锻件在车削加工后硬度增加及硬化程度,进行了720℃、780℃、800℃三个温度的退火试验,研究了退火温度对消除车削加工硬化的影响,为提高产品的交货性能、满足客户要求提供依据。%The H.S.S.products in condition of ready to be worked would become surface hardening in cut-ting working and affect the following application.It is researched the increased hardness as well as hardening extent of two forging pieces of H.S.S.M2 and M2Al after lathe work; the annealing tests under 720, 780 and 800 ℃are carried out, the influence of annealing temperature on eliminating lathe work hardening re-searched.Those works offer a reference to improve products delivery properties and meet demand of custom-ers.

  10. Zona hardening, zona drilling and assisted hatching: new achievements in assisted reproduction.

    De Vos, A; Van Steirteghem, A


    Prior to fertilization, the zona pellucida surrounding the mammalian oocyte acts as a species-specific sperm barrier and is involved in sperm binding. After fertilization, the zona plays a role in blocking polyspermic fertilization, it protects the integrity of the preimplantation embryo during early embryonic development, and also helps its oviductal transport. Zona hardening occurs naturally after fertilization in order to ensure this threefold function. A combination of lysins produced by the cleaving embryo or the uterus and physical expansion then reduces the zona thickness in preparation for hatching. Zona hardening, although not readily quantifiable, may also be induced by in vitro culture and by in vivo aging. Indeed, prolonged exposure of human oocytes and embryos to artificial culture conditions seems to impair their ability to implant. Implantation rates are also inversely correlated with advanced female age. Recently, failure of the embryonic zona pellucida to rupture following blastocyst expansion has been put forward as a possible contributing factor in implantation failure. In order to help embryos escape from their zonae during blastocyst expansion, different types of assisted hatching have been developed. Zona drilling involves the creation of an opening in the zona with acidified medium, whereas zona slitting is carried out in the same manner as partial zona dissection. In zona thinning, the zona is just made thinner over a certain area without a hole or a slit being created. More recently, laser-assisted hatching has been introduced. In vitro studies with both mouse and human embryos have indicated that an artificial gap in the zona pellucida significantly improves the hatching ability of blastocysts grown in vitro as compared to non-micromanipulated embryos. However, the clinical relevance of assisted hatching within an assisted reproduction program remains controversial and elusive. Very few randomized studies are available. Most reports are of

  11. Influences of copper on solidification structure and hardening behavior of high chromium cast irons

    WANG Jun; XIONG Ji; FAN Hong-yuan; SHEN Bao-luo; GAO Sheng-ji


    The influences of copper on microstructure and the hardening behavior of high chromium cast irons subjected to sub-critical treatment were investigated.The results show that the mierostructure of the as-cast high chromium cast irons consists of retained austenite,martensite and M7 C3 type eutectic carbide.When copper is added into high chromium cast irons,austenite and carbide contents are increased.The increased addition of copper content from 0%to 1.84%leads to the increase of austenite and carbide from 15.9%and 20.0% to 61.0%and 35.5%,respectively.In the process of sub-critical treatment,the retained austenite in the matrix can be precipitated into secondary carbides and then transforms into martensite in cooling process,which causes the secondary hardening of the alloy under sub-critical treatment.High chromium cast irons containing copper in sub-critical treatment appear the second hardening curve peak due to the precipitation of copper from supersaturated matrix.

  12. Effect of mixing sequence on the curing of amine-hardened epoxy/ alumina nanocomposites as assessed by optical refractometry


    Full Text Available High performance refractometry has been proven to be a useful tool to elucidate the isothermal curing process of nanocomposites. As a model system an amine-hardening epoxy filled with non-surface-treated alumina nanoparticles was selected. The tremendous resolution of this experimental technique is used to study morphological changes within nanocomposites via the refractive index. It is shown that these morphological changes are not simply due to the curing process but also depend on the sequence of mixing the nanoparticles either first into the resin or first into the hardener. Independent of the resin/hardener composition, the type of the mixing sequence discriminates systematically between two distinct refractive index curves produced by the curing process. The difference between the two refractive index curves increases monotonically with curing time, which underlines the importance of the initial molecular environment of the nanoparticles.

  13. Modifications on A-F hardening rule to assess ratcheting response of materials and its interaction with fatigue damage under uniaxial stress cycles

    Ahmadzadehrishehri, Gholamreza

    Ratcheting deformation is accumulated progressively over three distinct stages in materials undergoing asymmetrical cyclic stresses. The present thesis evaluates the triphasic ratcheting response of materials from two stand points: (i) Mechanistic approach at which stages of ratcheting progress over stress cycles was related to mechanistic parameters such as stress level, lifespan, mechanical properties and the softening/hardening response of materials. Mechanistic approach formulated in this thesis was employed to assess ratcheting strain over triphasic stages in various steel and copper alloys under uniaxial stress cycles. Good agreements were achieved between the predicted ratcheting strain values based on the proposed formulation and those of experimentally reported. (ii) Kinematic hardening rule approach at which the hardening rule was characterized by the yield surface translation mechanism and the corresponding plastic modulus calculated based on the consistency condition. Various cyclic plasticity models were employed to assess ratcheting response of materials under different loading conditions. The Armstrong-Frederick (A-F) hardening rule was taken as the backbone of ratcheting analysis developed in this thesis mainly due to less complexity and number of coefficients in the hardening rule as compared with other earlier developed hardening rules in the literature. To predict triphasic ratcheting strain over stress cycles, the A-F hardening rule has been further developed by means of new strain rate coefficients gamma 2 and delta. These coefficients improved the hardening rule capability to calibrate and control the rate of ratcheting over its progressive stages. The modified hardening formulation holds the coefficients of the hardening rule to control stress-strain hysteresis loops generated over stress cycles during ratcheting process plus the ratcheting rates over stages I, II, and III. These coefficients were calibrated and defined based on the applied

  14. Increases in the numerical density of GAT-1 positive puncta in the barrel cortex of adult mice after fear conditioning.

    Ewa Siucinska

    Full Text Available Three days of fear conditioning that combines tactile stimulation of a row of facial vibrissae (conditioned stimulus, CS with a tail shock (unconditioned stimulus, UCS expands the representation of "trained" vibrissae, which can be demonstrated by labeling with 2-deoxyglucose in layer IV of the barrel cortex. We have also shown that functional reorganization of the primary somatosensory cortex (S1 increases GABAergic markers in the hollows of "trained" barrels of the adult mouse. This study investigated how whisker-shock conditioning (CS+UCS affected the expression of puncta of a high-affinity GABA plasma membrane transporter GAT-1 in the barrel cortex of mice 24 h after associative learning paradigm. We found that whisker-shock conditioning (CS+UCS led to increase expression of neuronal and astroglial GAT-1 puncta in the "trained" row compared to controls: Pseudoconditioned, CS-only, UCS-only and Naïve animals. These findings suggest that fear conditioning specifically induces activation of systems regulating cellular levels of the inhibitory neurotransmitter GABA.

  15. High-Performance, Radiation-Hardened Electronics for Space Environments

    Keys, Andrew S.; Watson, Michael D.; Frazier, Donald O.; Adams, James H.; Johnson, Michael A.; Kolawa, Elizabeth A.


    The Radiation Hardened Electronics for Space Environments (RHESE) project endeavors to advance the current state-of-the-art in high-performance, radiation-hardened electronics and processors, ensuring successful performance of space systems required to operate within extreme radiation and temperature environments. Because RHESE is a project within the Exploration Technology Development Program (ETDP), RHESE's primary customers will be the human and robotic missions being developed by NASA's Exploration Systems Mission Directorate (ESMD) in partial fulfillment of the Vision for Space Exploration. Benefits are also anticipated for NASA's science missions to planetary and deep-space destinations. As a technology development effort, RHESE provides a broad-scoped, full spectrum of approaches to environmentally harden space electronics, including new materials, advanced design processes, reconfigurable hardware techniques, and software modeling of the radiation environment. The RHESE sub-project tasks are: SelfReconfigurable Electronics for Extreme Environments, Radiation Effects Predictive Modeling, Radiation Hardened Memory, Single Event Effects (SEE) Immune Reconfigurable Field Programmable Gate Array (FPGA) (SIRF), Radiation Hardening by Software, Radiation Hardened High Performance Processors (HPP), Reconfigurable Computing, Low Temperature Tolerant MEMS by Design, and Silicon-Germanium (SiGe) Integrated Electronics for Extreme Environments. These nine sub-project tasks are managed by technical leads as located across five different NASA field centers, including Ames Research Center, Goddard Space Flight Center, the Jet Propulsion Laboratory, Langley Research Center, and Marshall Space Flight Center. The overall RHESE integrated project management responsibility resides with NASA's Marshall Space Flight Center (MSFC). Initial technology development emphasis within RHESE focuses on the hardening of Field Programmable Gate Arrays (FPGA)s and Field Programmable Analog

  16. Embrittlement of irradiated ferritic/martensitic steels in the absence of irradiation hardening

    Klueh, R.L. [Oak Ridge Noational Laboratory, TN (United States); Shiba, K. [Japan Atomic Energy Agency, Tokai-mura, Naga-gun, Ibaraki-ken (Japan); Sokolov, M. [Oak Ridge National Laboratory, Materials Science and Technology Div., TN (United States)


    Full text of publication follows: Neutron irradiation of 9-12% Cr ferritic/martensitic steels below 425-450 deg. C produces microstructural defects that cause an increase in yield stress and ultimate tensile strength. This irradiation hardening causes embrittlement, which is observed in Charpy impact and toughness tests as an increase in ductile-brittle transition temperature (DBTT). Based on observations that show little change in strength in these steels irradiated above 425-450 deg. C, the general conclusion has been that no embrittlement occurs above this irradiation-hardening temperature regime. In a recent study of F82H steel irradiated at 300, 380, and 500 deg. C, irradiation hardening-an increase in yield stress-was observed in tensile specimens irradiated at the two lower temperatures, but no change was observed for the specimens irradiated at 500 deg. C. As expected, an increase in DBTT occurred for the Charpy specimens irradiated at 300 and 380 deg. C. However, there was an unexpected increase in the DBTT of the specimens irradiated at 500 deg. C. The observed embrittlement was attributed to the irradiation-accelerated precipitation of Laves phase. This conclusion was based on results from a detailed thermal aging study of F82H, in which tensile and Charpy specimens were aged at 500, 550, 600, and 650 deg. C to 30,000 h. These studies indicated that there was a decrease in yield stress at the two highest temperatures and essentially no change at the two lowest temperatures. Despite the strength decrease or no change, the DBTT increased for Charpy specimens irradiated at all four temperatures. Precipitates were extracted from thermally aged specimens, and the amount of precipitate was correlated with the increase in transition temperature. Laves phase was identified in the extracted precipitates by X-ray diffraction. Earlier studies on conventional elevated-temperature steels also showed embrittlement effects above the irradiation-hardening temperature

  17. Post-trial dopaminergic modulation of conditioned catalepsy: A single apomorphine induced increase/decrease in dopaminergic activation immediately following a conditioned catalepsy response can reverse/enhance a haloperidol conditioned and sensitized catalepsy response.

    Oliveira, Lucas Rangel; Dias, Flávia Regina Cruz; Santos, Breno Garone; Silva, Jade Leal Loureiro; Carey, Robert J; Carrera, Marinete Pinheiro


    Haloperidol can induce catalepsy and this drug effect can be conditioned as well as sensitized to contextual cues. We used a paired/unpaired Pavlovian conditioning protocol to establish haloperidol catalepsy conditioned and sensitized responses. Groups of rats were given 10 daily catalepsy tests following administration of vehicle (n=24) or haloperidol (1.0mg/kg) either paired (n=18) or unpaired (n=18) to testing. Subsequently, testing for conditioning was conducted and conditioning and sensitization of catalepsy were observed selectively in the paired group. Immediately following a second test for catalepsy conditioning, the groups were subdivided into 4 vehicle groups, 3 unpaired haloperidol groups and 3 paired haloperidol groups and were given one of three post-trial treatments (vehicle, 0.05mg/kg or 2.0mg/kg apomorphine). One day later the conditioned catalepsy test 3 was carried out and on the next day, a haloperidol challenge test was performed. The post-trial apomorphine treatments had major effects on the paired groups upon both conditioning and the haloperidol challenge test. The low dose apomorphine post-trial treatment enhanced both the conditioned and the haloperidol sensitized catalepsy responses. The high dose apomorphine post-trial treatment eliminated conditioned catalepsy and eliminated the initial acute catalepsy response to haloperidol that was induced in the vehicle control groups. These results demonstrate the sensitivity of conditioned drug cues to modification by increases/decreases in activity of the dopamine system in the immediate post-trial interval after a conditioning trial. This demonstration that post-trial dopaminergic drug treatments can modify conditioned drug behavior has broad implications for conditioned drug effects.

  18. Precipitation hardening in a 12%Cr-9%Ni-4%Mo-2%Cu stainless steel

    Haettestrand, Mats; Nilsson, Jan-Olof; Stiller, Krystyna; Liu Ping; Andersson, Marcus


    A combination of complementary techniques including one-dimensional and three-dimensional atom probe, energy-filtered transmission electron microscopy and conventional transmission electron microscopy has been used to assess the precipitation reactions at 475 deg. C in a 12%Cr-9%Ni-4%Mo-2%Cu precipitation hardening stainless steel. The continuous hardening up to at least 1000 h of ageing was attributed to a sequence of precipitation reactions involving nickel-rich precipitates nucleating at copper clusters followed by molybdenum-rich quasicrystalline precipitates and nickel-rich precipitates of type L1{sub 0}. An estimate of the relative contributions to the strength increment during tempering based on measurements of particle densities was performed. Nickel-rich precipitates were found to play the most important role up to about 40 h of ageing after which the effect of quasicrystalline particles became increasingly important.

  19. Critical buckling strain in high strength steel pipes using isotropic kinematic hardening

    Fathi, A.; Roger Cheng, J. J.; Adeeb, Samer [Department of Civil and Environmental Engineering, University of Alberta (Canada); Zhou, Joe [TransCanada Pipelines Ltd. (Canada)


    In the natural gas sector, the use of high strength steel pipelines (HSSP) to transport huge volumes over long distances is increasing as it yields important savings in both capital and operational expenditures. In order to design HSSP, the critical buckling strain as to be taken into consideration but the models so far developed have been for isotropic materials while important material anisotropy is observed on HSSP due to their manufacturing process. The paper presents a model to assess the critical buckling strain of HSSP. An isotropic-kinematic hardening material model was developed and isotropic and anisotropic models were used to simulate pressurized and non-pressurized HSSP and were compared to test results. Results showed that the isotropic model is not suitable for predicting the buckling strain of HSSP but that the isotropic-kinematic hardening material model is. A model to better predict the buckling strain of HSSP was developed and successfully tested herein.


    Chuantao Hou; Zhenhuan Li; Minsheng Huang; Chaojun Ouyang


    A two-dimensional discrete dislocation dynamics (DDD) technology by Giessen and Needleman (1995), which has been extended by integrating a dislocation-grain boundary interaction model, is used to computationally analyze the micro-cyclic plastic response of polycrystals containing micron-sized grains, with special attentions to significant influence of dislocationpenetrable grain boundaries (GBs) on the micro-plastic cyclic responses of polycrystals and underlying dislocation mechanism. Toward this end, a typical polycrystalline rectangular specimen under simple tension-compression loading is considered. Results show that, with the increase of cycle accumulative strain, continual dislocation accumulation and enhanced dislocation-dislocation interactions induce the cyclic hardening behavior; however, when a dynamic balance among dislocation nucleation, penetration through GB and dislocation annihilation is approximately established, cyclic stress gradually tends to saturate. In addition, other factors, including the grain size, cyclic strain amplitude and its history, also have considerable influences on the cyclic hardening and saturation.

  1. Simulation and experimental analyses of dynamic strain aging of a supersaturated age hardenable aluminum alloy

    Anjabin, N. [Department of Materials Science and Engineering, Sharif University of Technology, Tehran 11365-9466 (Iran, Islamic Republic of); Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Karimi Taheri, A. [Department of Materials Science and Engineering, Sharif University of Technology, Tehran 11365-9466 (Iran, Islamic Republic of); Kim, H.S., E-mail: [Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)


    In this paper, dynamic strain aging (DSA) behavior in a temperature range of (25–235 °C) and strain rate range of (10{sup −4}–5×10{sup −2} s{sup −1}) was investigated using a supersaturated age hardenable aluminum alloy. It was found that two mechanisms consisted of pinning of solute atoms to mobile dislocations and dynamic precipitation, were responsible for DSA in the testing conditions. The effects of both mechanisms on the macroscopic flow curve were studied using experimental and improved physically based material modeling approaches. It was shown that both phenomena lead to a negative strain rate hardening in the alloy. Dynamic precipitation acting at high temperature results in considerable work hardening and material strengthening. Taking into account these microstructural phenomena, the effects of deformation temperature and strain rate on the macroscopic flow behavior were discussed. The proposed modeling approach could successfully predict the experimental flow curve, possible jerky flow, and the corresponding serration types. Also, the spatial nucleation and propagation of the localized deformation bands along the specimen gauge length were recorded by a digital image correlation method and compared with the proposed model predictions.

  2. Intense 2-cycle laser pulses induce time-dependent bond-hardening in a polyatomic molecule

    Dota, K; Tiwari, A K; Dharmadhikari, J A; Dharmadhikari, A K; Mathur, D


    A time-dependent bond-hardening process is discovered in a polyatomic molecule (tetramethyl silane, TMS) using few-cycle pulses of intense 800 nm light. In conventional mass spectrometry, symmetrical molecules like TMS do not exhibit a prominent molecular ion (TMS$^+$) as unimolecular dissociation into [Si(CH$_3$)$_3]^+$ proceeds very fast. Under strong field and few-cycle conditions, this dissociation channel is defeated by time-dependent bond-hardening: a field-induced potential well is created in the TMS$^+$ potential energy curve that effectively traps a wavepacket. The time-dependence of this bond hardening process is verified using longer-duration ($\\geq$ 100 fs) pulses; the relatively "slower" fall-off of optical field in such pulses allows the initially trapped wavepacket to leak out, thereby rendering TMS$^+$ unstable once again. Our results are significant as they demonstrate (i) optical generation of polyatomic ions that are normally inaccessible and (ii) optical control of dynamics in strong field...

  3. Effects of Different Seedling Densities on the Cultivation and Hardening of Eucalypt Seedlings%不同炼苗密度对桉树轻基质幼苗的影响

    许宇星; 李超; 张国武


    通过对5个月生4种不同炼苗密度的尾巨桉优良无性系 DH32-29幼苗树高、地径及各器官生物量进行调查分析,结果表明:4种不同炼苗密度间苗高无显著差异;而地径差异达到极显著水平,并呈极显著负相关;不同炼苗密度单株间及各器官生物量均差异显著,单株生物量、叶片、茎干与根系的生物量均随炼苗密度增加而降低;考虑到空间利用率、通风保水性及疾病易感程度综合分析,炼苗密度以45株·盘-1效果最佳。%Five-month-old seedlings of the hybrid eucalypt clone DH32-29 that had been grown under four different densities during seedling hardening were investigated. Growth, biomass of different organs and the condition of roots were analyzed in February 2014. Different seedling hardening densities had no significant effect on subsequent height growth but extremely negative impact on the basal diameter growth. Different seedling hardening densities had significant effects on subsequent biomass; the biomass of leaves, stems and roots decreased as the seedling hardening density increased. Meanwhile, considering the space utilization, ventilation, water retention and degree of disease susceptibility, a density of 45 plants/tray (for 96 cell trays) was the best choice for cultivation of quality hybrid eucalypt seedlings.

  4. Simulation of the Press Hardening Process and Prediction of the Final Mechanical Material Properties

    Hochholdinger, Bernd; Hora, Pavel; Grass, Hannes; Lipp, Arnulf


    Press hardening is a well-established production process in the automotive industry today. The actual trend of this process technology points towards the manufacturing of parts with tailored properties. Since the knowledge of the mechanical properties of a structural part after forming and quenching is essential for the evaluation of for example the crash performance, an accurate as possible virtual assessment of the production process is more than ever necessary. In order to achieve this, the definition of reliable input parameters and boundary conditions for the thermo-mechanically coupled simulation of the process steps is required. One of the most important input parameters, especially regarding the final properties of the quenched material, is the contact heat transfer coefficient (IHTC). The CHTC depends on the effective pressure or the gap distance between part and tool. The CHTC at different contact pressures and gap distances is determined through inverse parameter identification. Furthermore a simulation strategy for the subsequent steps of the press hardening process as well as adequate modeling approaches for part and tools are discussed. For the prediction of the yield curves of the material after press hardening a phenomenological model is presented. This model requires the knowledge of the microstructure within the part. By post processing the nodal temperature history with a CCT diagram the quantitative distribution of the phase fractions martensite, bainite, ferrite and pearlite after press hardening is determined. The model itself is based on a Hockett-Sherby approach with the Hockett-Sherby parameters being defined in function of the phase fractions and a characteristic cooling rate.

  5. Neutron energy spectrum influence on irradiation hardening and microstructural development of tungsten

    Fukuda, Makoto; Kiran Kumar, N. A. P.; Koyanagi, Takaaki; Garrison, Lauren M.; Snead, Lance L.; Katoh, Yutai; Hasegawa, Akira


    Neutron irradiation to single crystal pure tungsten was performed in the mixed spectrum High Flux Isotope Reactor (HFIR). To investigate the influences of neutron energy spectrum, the microstructure and irradiation hardening were compared with previous data obtained from the irradiation campaigns in the mixed spectrum Japan Material Testing Reactor (JMTR) and the sodium-cooled fast reactor Joyo. The irradiation temperatures were in the range of ∼90-∼800 °C and fast neutron fluences were 0.02-9.00 × 1025 n/m2 (E > 0.1 MeV). Post irradiation evaluation included Vickers hardness measurements and transmission electron microscopy. The hardness and microstructure changes exhibited a clear dependence on the neutron energy spectrum. The hardness appeared to increase with increasing thermal neutron flux when fast fluence exceeds 1 × 1025 n/m2 (E > 0.1 MeV). Irradiation induced precipitates considered to be χ- and σ-phases were observed in samples irradiated to >1 × 1025 n/m2 (E > 0.1 MeV), which were pronounced at high dose and due to the very high thermal neutron flux of HFIR. Although the irradiation hardening mainly caused by defects clusters in a low dose regime, the transmutation-induced precipitation appeared to impose additional significant hardening of the tungsten.

  6. Impact of mild temperature hardening on thermotolerance, fecundity, and Hsp gene expression in Liriomyza huidobrensis.

    Huang, Li-Hua; Chen, Bing; Kang, Le


    The pea leafminer, Liriomyza huidobrensis, is one of the most important economic insect pests around the world. Its population fluctuates greatly with seasonal change in China, and temperature was thought to be one of the important reasons. In attempt to further explore the impact of disadvantageous temperature on L. huidobrensis, 1-day-old adults were shocked at various temperatures (10, 25, 32, and 35 degrees C, respectively) for 4h, and the effects on thermotolerance, feeding, and fecundity were studied. Meanwhile the expression of five heat shock genes (hsp90, 70, 60, 40, and 20) was examined by real-time quantitative PCR. Our results showed that both 32 and 35 degrees C hardenings remarkably increased adult heat resistance, whereas cold tolerance was not improved accordingly. No cross resistance in response to cold and heat stresses was observed. Both adult feeding and fecundity were dramatically reduced, but no effect was observed on egg hatching, larval survival, pupal eclosion, or sex ratio. The results indicate that the deleterious effect on fecundity is the result of direct cessation of oviposition during the period of stress. Simultaneously, the mRNA levels of hsp70 and hsp20 significantly increased upon thermal hardening. Taken together, our results suggest that mild heat hardening improves thermotolerance of L. huidobrensis at the cost of impairment on fecundity, and the induced expression of hsp70 and hsp20 may play an important role in balancing the functional tradeoff.

  7. Hardening by ion implantation of VT1-0 alloy having different grain size

    Nikonenko, Alisa, E-mail:; Kurzina, Irina, E-mail: [National Research Tomsk State University, 36, Lenin Str., 634050, Tomsk (Russian Federation); Popova, Natalya, E-mail: [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Institute of Strength Physics and Materials Science, SB RAS, 2/4, Akademicheskii Ave., 634021, Tomsk Russia (Russian Federation); Nikonenko, Elena, E-mail: [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); National Research Tomsk Polytechnic University, 30, Lenin Str., 634050, Tomsk (Russian Federation); Kalashnikov, Mark, E-mail: [Institute of Strength Physics and Materials Science, SB RAS, 2/4, Akademicheskii Ave., 634021, Tomsk Russia (Russian Federation)


    The paper presents a transmission electron microscopy (TEM) study of the structural and phase state of commercially pure titanium implanted by aluminum ions. TEM study has been carried out for two types of grains, namely coarse (0.4 µm) and small (0.5 µm). This paper presents details of the yield stress calculations and the analysis of strength components for the both grain types in two areas of the modified layer: at a distance of 0-150 nm (surface area I) and ∼300 nm (central area II) from the irradiated surface. It is shown that the ion implantation results in a considerable hardening of the entire thickness of the implanted layer in the both grain types. The grain size has, however, a different effect on the yield stress in areas I and II. Thus, near the ion-alloyed layer, the yield stress decreases with the increase of the grain size, whilst area II demonstrates its increase. Moreover, the contribution to the general hardening of the alloy made by certain hardening mechanisms differs from contributions made by each of these mechanisms in each certain case.

  8. Embrittlement of irradiated ferritic/martensitic steels in the absence of irradiation hardening

    Klueh, R.L. [Oak Ridge National Laboratory, Materials Science and Technology Division, P.O. 2008 MS6138, Oak Ridge, TN 37831-6138 (United States)], E-mail:; Shiba, K. [Japan Atomic Energy Agency, Toki-Mura, Ibaraki (Japan); Sokolov, M.A. [Oak Ridge National Laboratory, Materials Science and Technology Division, P.O. 2008 MS6138, Oak Ridge, TN 37831-6138 (United States)


    Irradiation damage caused by neutron irradiation below 425-450 deg. C of 9-12% Cr ferritic/martensitic steels produces microstructural defects that cause an increase in yield stress. This irradiation hardening causes embrittlement observed in a Charpy impact test as an increase in the ductile-brittle transition temperature. Little or no change in strength is observed in steels irradiated above 425-450 deg. C. Therefore, the general conclusion has been that no embrittlement occurs above these temperatures. In a recent study, significant embrittlement was observed in F82H steel irradiated at 500 deg. C to 5 and 20 dpa without any change in strength. Earlier studies on several conventional steels also showed embrittlement effects above the irradiation-hardening temperature regime. Indications are that this embrittlement is caused by irradiation-accelerated or irradiation-induced precipitation. Observations of embrittlement in the absence of irradiation hardening that were previously reported in the literature have been examined and analyzed with computational thermodynamics calculations to illuminate and understand the effect.

  9. Combinative hardening effects of precipitation in a commercial aged Al–Cu–Li–X alloy

    Chen, Zhongwei, E-mail:; Zhao, Kai; Fan, Li


    The combinative effects of precipitates on microstructure and hardness of an Al–Cu–Li–X alloy (X=Mg, Zn, Mn, Zr) in artificial ageing of 165 °C were investigated by a transmission electron microscopy and hardness test. Results show that the hardness appears at regression in early ageing stage and increases rapidly during subsequent ageing of 16 h. Hardening effects of as-quenched sample are mainly attributed to β′ (Al{sub 3}Zr) dispersoids, quenched-in vacancies and dislocations. Though most of the fine and uniform precipitates θ′ (Al{sub 2}Cu), δ′ (Al{sub 3}Li), σ (Al{sub 5}Cu{sub 6}Mg{sub 2}) and GP zone came into being in ageing of 0.5 h, annihilation of quenched-in vacancies and reduction of dislocation were ascribed to the hardening regression at early stages of ageing. As further ageing is in progress, all precipitates including T{sub 1} (Al{sub 2}CuLi), σ, δ′ and θ′ have appeared during the ageing of 16 h that follows, and their combinative hardening effects are responsible for the rapid hardness increase at peak-ageing.

  10. Microstructural change and precipitation hardening in melt-spun Mg–X–Ca alloys

    Won-Wook Park, Bong-Sun You, Byoung-Gi Moon and Wan-Chul Kim


    Full Text Available Mg–Al–Si–Ca and Mg–Zn–Ca base alloys were rapidly solidified by melt spinning at the cooling rate of about a million K/s. The melt-spun ribbons were aged in the range 100–400°C for 1 h. The effect of additional elements on microstructural change and precipitation hardening after heat treatment was investigated using TEM, XRD and a Vickers microhardness tester. Age hardening occurred after aging at 200°C in the Mg–Al–Si–Ca alloys mainly due to the formation of Al2Ca and Mg2Ca phases, whereas in the Mg–Zn–Ca alloys mostly due to the distribution of Mg2Ca. TEM results revealed that spherical Al2Ca precipitate has the coherent interface with the matrix. Considering the total amount of additional elements, Mg–Zn–Ca alloys showed higher hardness and smaller size of precipitates than Mg–Al–Si–Ca alloys. With the increase of Ca content, the hardness values of the aged ribbons were increased. Among the alloys, Mg–6Zn–5Ca alloy showed the maximum value of age hardening peak(Hv:180 after aging at 200°C for 1 h.

  11. Increasing body condition score is positively associated interleukin-6 and monocyte chemoattractant protein-1 in Labrador retrievers.

    Frank, Lauren; Mann, Sabine; Levine, Corri B; Cummings, Bethany P; Wakshlag, Joseph J


    The accumulation of excess body fat is a growing problem in dogs as well as people. Contrary to prior understanding of adipose tissue, fat is now considered to be an active endocrine organ that promotes a chronic low-grade inflammatory state often characterized by an increase in pro-inflammatory cytokines and chemokines. These have been implicated in several obesity-related disorders such as insulin resistance, cardiovascular disease, and neoplasia. The purpose of this study was to characterize fasting plasma cytokine concentrations in ninety-two healthy client-owned Labrador retriever dogs of various ages and body condition scores. The dogs were grouped according to body condition score (BCS) into three categories, lean, overweight and obese. The following cytokines and chemokines were evaluated; tumor necrosis factor-alpha, interleukin-2, interleukin-6, interleukin-8, and monocyte chemotactic protein-1 (TNF-α, IL-2, IL-6, IL-8, MCP-1). Our results indicated that fasting plasma IL-6 and MCP-1 concentrations are associated with increasing BCS. This data suggest that certain markers of inflammation increase with increasing body condition score, and that dogs, similar to humans, may be fostering a chronic inflammatory state due to obesity.

  12. A comparison of heavy ion induced single event upset susceptibility in unhardened 6T/SRAM and hardened ADE/SRAM

    Wang, Bin; Zeng, Chuanbin; Geng, Chao; Liu, Tianqi; Khan, Maaz; Yan, Weiwei; Hou, Mingdong; Ye, Bing; Sun, Youmei; Yin, Yanan; Luo, Jie; Ji, Qinggang; Zhao, Fazhan; Liu, Jie


    Single event upset (SEU) susceptibility of unhardened 6T/SRAM and hardened active delay element (ADE)/SRAM, fabricated with 0.35 μm silicon-on-insulator (SOI) CMOS technology, was investigated at heavy ion accelerator. The mechanisms were revealed by the laser irradiation and resistor-capacitor hardened techniques. Compared with conventional 6T/SRAM, the hardened ADE/SRAM exhibited higher tolerance to heavy ion irradiation, with an increase of about 80% in the LET threshold and a decrease of ∼64% in the limiting upset cross-section. Moreover, different probabilities between 0 → 1 and 1 → 0 transitions were observed, which were attributed to the specific architecture of ADE/SRAM memory cell. Consequently, the radiation-hardened technology can be an attractive alternative to the SEU tolerance of the device-level.

  13. Strain-hardening and warm deformation behaviors of extruded Mg–Sn–Yb alloy sheet

    Jing Jiang


    Full Text Available Strain-hardening and warm deformation behaviors of extruded Mg–2Sn–0.5Yb alloy (at.% sheet were investigated in uniaxial tensile test at temperatures of 25–250 °C and strain rates of 1 × 10−3 s−1–0.1 s−1. The data fit with the Kocks–Mecking type plots were used to show different stages of strain hardening. Besides III-stage and IV-stage, the absence of the II-stage strain hardening at room temperature should be related to the sufficient dynamic recrystallization during extrusion. The decrease of strain hardening ability of the alloy after yielding was attributed to the reduction of dislocation density with increasing testing temperature. Strain rate sensitivity (SRS was significantly enhanced with increasing temperature, and the corresponding m-value was calculated as 0.07–0.12, which indicated that the deformation mechanism was dominated by the climb-controlled dislocation creep at 200 °C. Furthermore, the grain boundary sliding (GBS was activated at 250 °C, which contributed to the higher SRS. The activation energy was calculated as 213.67 kJ mol−1, which was higher than that of lattice diffusion or grain boundary self-diffusion. In addition, the alloy exhibited a quasi superplasticity at 250 °C with a strain rate of 1 × 10−3 s−1, which was mainly related to the fine microstructure and the presence of the Mg2Sn and Mg2(Sn,Yb particles.

  14. Elevated Temperature and CO2 Stimulate Late-Season Photosynthesis But Impair Cold Hardening in Pine.

    Chang, Christine Y; Fréchette, Emmanuelle; Unda, Faride; Mansfield, Shawn D; Ensminger, Ingo


    Rising global temperature and CO2 levels may sustain late-season net photosynthesis of evergreen conifers but could also impair the development of cold hardiness. Our study investigated how elevated temperature, and the combination of elevated temperature with elevated CO2, affected photosynthetic rates, leaf carbohydrates, freezing tolerance, and proteins involved in photosynthesis and cold hardening in Eastern white pine (Pinus strobus). We designed an experiment where control seedlings were acclimated to long photoperiod (day/night 14/10 h), warm temperature (22°C/15°C), and either ambient (400 μL L(-1)) or elevated (800 μmol mol(-1)) CO2, and then shifted seedlings to growth conditions with short photoperiod (8/16 h) and low temperature/ambient CO2 (LTAC), elevated temperature/ambient CO2 (ETAC), or elevated temperature/elevated CO2 (ETEC). Exposure to LTAC induced down-regulation of photosynthesis, development of sustained nonphotochemical quenching, accumulation of soluble carbohydrates, expression of a 16-kD dehydrin absent under long photoperiod, and increased freezing tolerance. In ETAC seedlings, photosynthesis was not down-regulated, while accumulation of soluble carbohydrates, dehydrin expression, and freezing tolerance were impaired. ETEC seedlings revealed increased photosynthesis and improved water use efficiency but impaired dehydrin expression and freezing tolerance similar to ETAC seedlings. Sixteen-kilodalton dehydrin expression strongly correlated with increases in freezing tolerance, suggesting its involvement in the development of cold hardiness in P. strobus Our findings suggest that exposure to elevated temperature and CO2 during autumn can delay down-regulation of photosynthesis and stimulate late-season net photosynthesis in P. strobus seedlings. However, this comes at the cost of impaired freezing tolerance. Elevated temperature and CO2 also impaired freezing tolerance. However, unless the frequency and timing of extreme low

  15. Inhibition of environmental fatigue crack propagation in age-hardenable aluminum alloys

    Warner, Jenifer S.

    Age-hardenable aluminum alloys, such as C47A-T86 (Al-Cu-Li) and 7075-T651 (Al-Zn-Mg-Cu), used in aerospace structures are susceptible to environment assisted fatigue crack propagation (EFCP) by hydrogen environment embrittlement. This research demonstrates effective inhibition of EFCP in C47A-T86 and 7075-T651 under both full immersion in aqueous chloride solution and atmospheric exposure which more accurately describes aircraft service conditions. Inhibition is attributed to the presence of a crack tip passive film reducing H production and uptake, as explained by the film rupture-hydrogen embrittlement mechanism, and can be accomplished through both addition of a passivating ion (ion-assisted inhibition) and localized-alloy corrosion creating passivating conditions (self inhibition). Addition of molybdate to both bulk chloride solution and surface chloride droplets eliminates the effect of environment on fatigue crack propagation in C47A-T86 and 7075-1651 at sufficiently low loading frequencies and high stress ratio by yielding crack growth rates equivalent to those for fatigue in ultra high vacuum. The preeminent corrosion inhibitor, chromate, has not been reported to produce such complete inhibition. Inhibition is promoted by reduced loading frequency, increased crack tip molybdate concentration, and potential at or anodic to free corrosion; each of which favors passivity. The inhibiting effect of molybdate parallels chromate, establishing molybdate as a viable chromate replacement inhibitor. The ability of molybdate to inhibit EFCP is enhanced by atmospheric exposures producing surface electrolyte droplets; crack growth rates are reduced by an order of magnitude under loading frequencies as high as 30 Hz, a frequency at which inhibition was not possible under full immersion. Al-Cu-Mg/Li alloys, including 2024-T351, are capable of self inhibition of EFCP. This behavior is attributed to localized corrosion through dealloying of anodic Al2CuMg or Al2Cu

  16. NINJA: a noninvasive framework for internal computer security hardening

    Allen, Thomas G.; Thomson, Steve


    Vulnerabilities are a growing problem in both the commercial and government sector. The latest vulnerability information compiled by CERT/CC, for the year ending Dec. 31, 2002 reported 4129 vulnerabilities representing a 100% increase over the 2001 [1] (the 2003 report has not been published at the time of this writing). It doesn"t take long to realize that the growth rate of vulnerabilities greatly exceeds the rate at which the vulnerabilities can be fixed. It also doesn"t take long to realize that our nation"s networks are growing less secure at an accelerating rate. As organizations become aware of vulnerabilities they may initiate efforts to resolve them, but quickly realize that the size of the remediation project is greater than their current resources can handle. In addition, many IT tools that suggest solutions to the problems in reality only address "some" of the vulnerabilities leaving the organization unsecured and back to square one in searching for solutions. This paper proposes an auditing framework called NINJA (acronym for Network Investigation Notification Joint Architecture) for noninvasive daily scanning/auditing based on common security vulnerabilities that repeatedly occur in a network environment. This framework is used for performing regular audits in order to harden an organizations security infrastructure. The framework is based on the results obtained by the Network Security Assessment Team (NSAT) which emulates adversarial computer network operations for US Air Force organizations. Auditing is the most time consuming factor involved in securing an organization's network infrastructure. The framework discussed in this paper uses existing scripting technologies to maintain a security hardened system at a defined level of performance as specified by the computer security audit team. Mobile agents which were under development at the time of this writing are used at a minimum to improve the noninvasiveness of our scans. In general, noninvasive

  17. Embryos of a moss can be hardened to desiccation tolerance: effects of rate of drying on the timeline of recovery and dehardening in Aloina ambigua (Pottiaceae).

    Brinda, John C; Stark, Lloyd R; Clark, Theresa A; Greenwood, Joshua L


    Embryonic sporophytes of the moss Aloina ambigua are inducibly desiccation tolerant (DT). Hardening to DT describes a condition of temporary tolerance to a rapid-drying event conferred by a previous slow-drying event. This paper aimed to determine whether sporophytic embryos of a moss can be hardened to DT, to assess how the rate of desiccation influences the post-rehydration dynamics of recovery, hardening and dehardening, and to determine the minimum rate of drying for embryos and shoots. Embryos were exposed to a range of drying rates using wetted filter paper in enclosed Petri dishes, monitoring relative humidity (RH) inside the dish and equilibrating tissues with 50% RH. Rehydrated embryos and shoots were subjected to a rapid-drying event at intervals, allowing assessments of recovery, hardening and dehardening times. The minimum rate of slow drying for embryonic survival was ∼3·5 h and for shoots ∼9 h. Hardening to DT was dependent upon the prior rate of drying. When the rate of drying was extended to 22 h, embryonic hardening was strong (>50% survival) with survival directly proportional to the post-rehydration interval preceding rapid drying. The recovery time (repair/reassembly) was so short as to be undetectable in embryos and shoots desiccated gradually; however, embryos dried in desiccating event. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email:

  18. Transgenic alfalfa (Medicago sativa) with increased sucrose phosphate synthase activity shows enhanced growth when grown under N2-fixing conditions.

    Gebril, Sayed; Seger, Mark; Villanueva, Fabiola Muro; Ortega, Jose Luis; Bagga, Suman; Sengupta-Gopalan, Champa


    Overexpression of SPS in alfalfa is accompanied by early flowering, increased plant growth and an increase in elemental N and protein content when grown under N2-fixing conditions. Sucrose phosphate synthase (SPS; EC is the key enzyme in the synthesis of sucrose in plants. The outcome of overexpression of SPS in different plants using transgenic approaches has been quite varied, but the general consensus is that increased SPS activity is associated with the production of new sinks and increased sink strength. In legumes, the root nodule is a strong C sink and in this study our objective was to see how increasing SPS activity in a legume would affect nodule number and function. Here we have transformed alfalfa (Medicago sativa, cv. Regen SY), with a maize SPS gene driven by the constitutive CaMV35S promoter. Our results showed that overexpression of SPS in alfalfa, is accompanied by an increase in nodule number and mass and an overall increase in nitrogenase activity at the whole plant level. The nodules exhibited an increase in the level of key enzymes contributing to N assimilation including glutamine synthetase and asparagine synthetase. Moreover, the stems of the transformants showed higher level of the transport amino acids, Asx, indicating increased export of N from the nodules. The transformants exhibited a dramatic increase in growth both of the shoots and roots, and earlier flowering time, leading to increased yields. Moreover, the transformants showed an increase in elemental N and protein content. The overall conclusion is that increased SPS activity improves the N status and plant performance, suggesting that the availability of more C in the form of sucrose enhances N acquisition and assimilation in the nodules.

  19. Increasing incidence of statin prescribing for the elderly without previous cardiovascular conditions:  A nation wide register study

    Kildemoes, Helle Wallach; Andersen, Morten

    Supported by the growing evidence of the beneficial effects of statins in a range of conditions, statin utilization has increased considerably in most Western countries over the last decade. Objectives To estimate to what extent a widening of indication scope for statins accounts for the increasi...... for initiating statin treatment, including the "abolition of ageism". The fact that treatment incidence grew most among elderly without disease markers reflects a changing prescribing behaviours among general practitioners, presumably related to an increased use of risk scoring....

  20. PKMzeta inhibition reverses learning-induced increases in hippocampal synaptic strength and memory during trace eyeblink conditioning.

    Noelia Madroñal

    Full Text Available A leading candidate in the process of memory formation is hippocampal long-term potentiation (LTP, a persistent enhancement in synaptic strength evoked by the repetitive activation of excitatory synapses, either by experimental high-frequency stimulation (HFS or, as recently shown, during actual learning. But are the molecular mechanisms for maintaining synaptic potentiation induced by HFS and by experience the same? Protein kinase Mzeta (PKMzeta, an autonomously active atypical protein kinase C isoform, plays a key role in the maintenance of LTP induced by tetanic stimulation and the storage of long-term memory. To test whether the persistent action of PKMzeta is necessary for the maintenance of synaptic potentiation induced after learning, the effects of ZIP (zeta inhibitory peptide, a PKMzeta inhibitor, on eyeblink-conditioned mice were studied. PKMzeta inhibition in the hippocampus disrupted both the correct retrieval of conditioned responses (CRs and the experience-dependent persistent increase in synaptic strength observed at CA3-CA1 synapses. In addition, the effects of ZIP on the same associative test were examined when tetanic LTP was induced at the hippocampal CA3-CA1 synapse before conditioning. In this case, PKMzeta inhibition both reversed tetanic LTP and prevented the expected LTP-mediated deleterious effects on eyeblink conditioning. Thus, PKMzeta inhibition in the CA1 area is able to reverse both the expression of trace eyeblink conditioned memories and the underlying changes in CA3-CA1 synaptic strength, as well as the anterograde effects of LTP on associative learning.

  1. Comprehensive assessment of geographic variation in heat tolerance and hardening capacity in populations of Drosophila melanogaster from eastern Australia

    Sgro, Carla M.; Overgaard, Johannes; Kristensen, Torsten Nygård


    We examined latitudinal variation in adult and larval heat tolerance in Drosophila melanogaster from eastern Australia. Adults were assessed using static and ramping assays. Basal and hardened static heat knockdown time showed significant linear clines; heat tolerance increased towards the tropics...

  2. Age-hardenability and related microstructural changes during and after phase transformation in an Au-Ag-Cu-based dental alloy

    Hyung-Il Kim


    Full Text Available The aim of this study was to clarify how the microstructural changes during and after phase transformation determine the age-hardenability of an Au-Ag-Cu-based dental alloy. The rapid increase in hardness in the initial stage was the result of rapid atomic diffusion by spinodal decomposition into metastable Ag-rich' and Cu-rich' phases. The constant hardening after apparent initial hardening was the result of a subsequent transformation of the metastable Ag-rich' and Cu-rich' phases to the stable Ag-rich α1phase and AuCu I phase through the metastable AuCu I' phase. During the increase in hardness, fine block-like structure with high coherency formed in the grain interior, which changed to a fine cross-hatched structure. A relatively coarse lamellar structure composed of Ag-rich α1and AuCu I phases grew from the grain boundaries, initiating softening before the grain interior reached its maximum hardness. As a result, the spinodal decomposition attributed to rapid hardening by forming the fine block-like structure, and the subsequent ordering into AuCu I, which is a famous hardening mechanism, weakened its hardening effect by accelerating the lamellar-forming grain boundary reaction.

  3. Age-hardenability and related microstructural changes during and after phase transformation in an Au-Ag-Cu-based dental alloy

    Hyung-Il Kim


    Full Text Available The aim of this study was to clarify how the microstructural changes during and after phase transformation determine the age-hardenability of an Au-Ag-Cu-based dental alloy. The rapid increase in hardness in the initial stage was the result of rapid atomic diffusion by spinodal decomposition into metastable Ag-rich' and Cu-rich' phases. The constant hardening after apparent initial hardening was the result of a subsequent transformation of the metastable Ag-rich' and Cu-rich' phases to the stable Ag-rich α1phase and AuCu I phase through the metastable AuCu I' phase. During the increase in hardness, fine block-like structure with high coherency formed in the grain interior, which changed to a fine cross-hatched structure. A relatively coarse lamellar structure composed of Ag-rich α1and AuCu I phases grew from the grain boundaries, initiating softening before the grain interior reached its maximum hardness. As a result, the spinodal decomposition attributed to rapid hardening by forming the fine block-like structure, and the subsequent ordering into AuCu I, which is a famous hardening mechanism, weakened its hardening effect by accelerating the lamellar-forming grain boundary reaction.

  4. A radiation-hardened SOI-based FPGA

    Han Xiaowei; Gao Jiantou; Wang Jian; Li Ming; Liu Guizhai; Zhang Feng; Guo Xufeng; Stanley L.Chen; Liu Zhongli; Yu Fang; Zhao Kai; Wu Lihua; Zhao Yan; Li Yan; Zhang Qianli; Chen Liang; Zhang Guoquan; Li Jianzhong; Yang Bo


    A radiation-hardened SRAM-based field programmable gate array VS 1000 is designed and fabricated with a 0.5 μm partial-depletion silicon-on-insulator logic process at the CETC 58th Institute.The new logic cell (LC),with a multi-mode based on 3-input look-up-table (LUT),increases logic density about 12% compared to a traditional 4-input LUT.The logic block (LB),consisting of 2 LCs,can be used in two functional modes:LUT mode and distributed read access memory mode.The hierarchical routing channel block and switch block can significantly improve the flexibility and routability of the routing resource.The VS1000 uses a CQFP208 package and contains 392 reconfigurable LCs,112 reconfigurable user I/Os and IEEE 1149.1 compatible with boundaryscan logic for testing and programming.The function test results indicate that the hardware and software cooperate successfully and the VS 1000 works correctly.Moreover,the radiation test results indicate that the VS 1000 chip has total dose tolerance of 100 krad(Si),a dose rate survivability of 1.5 × 1011 rad(Si)/s and a neutron fluence immunity of 1 × 1014 n/cm2.

  5. Yield Hardening of Electrorheological Fluids in Channel Flow

    Helal, Ahmed; Qian, Bian; McKinley, Gareth H.; Hosoi, A. E.


    Electrorheological fluids offer potential for developing rapidly actuated hydraulic devices where shear forces or pressure-driven flow are present. In this study, the Bingham yield stress of electrorheological fluids with different particle volume fractions is investigated experimentally in wall-driven and pressure-driven flow modes using measurements in a parallel-plate rheometer and a microfluidic channel, respectively. A modified Krieger-Dougherty model can be used to describe the effects of the particle volume fraction on the yield stress and is in good agreement with the viscometric data. However, significant yield hardening in pressure-driven channel flow is observed and attributed to an increase and eventual saturation of the particle volume fraction in the channel. A phenomenological physical model linking the densification and consequent microstructure to the ratio of the particle aggregation time scale compared to the convective time scale is presented and used to predict the enhancement in yield stress in channel flow, enabling us to reconcile discrepancies in the literature between wall-driven and pressure-driven flows.

  6. A radiation-hardened SOI-based FPGA

    Xiaowei, Han; Lihua, Wu; Yan, Zhao; Yan, Li; Qianli, Zhang; Liang, Chen; Guoquan, Zhang; Jianzhong, Li; Bo, Yang; Jiantou, Gao; Jian, Wang; Ming, Li; Guizhai, Liu; Feng, Zhang; Xufeng, Guo; Chen, Stanley L.; Zhongli, Liu; Fang, Yu; Kai, Zhao


    A radiation-hardened SRAM-based field programmable gate array VS1000 is designed and fabricated with a 0.5 μm partial-depletion silicon-on-insulator logic process at the CETC 58th Institute. The new logic cell (LC), with a multi-mode based on 3-input look-up-table (LUT), increases logic density about 12% compared to a traditional 4-input LUT The logic block (LB), consisting of 2 LCs, can be used in two functional modes: LUT mode and distributed read access memory mode. The hierarchical routing channel block and switch block can significantly improve the flexibility and routability of the routing resource. The VS1000 uses a CQFP208 package and contains 392 reconfigurable LCs, 112 reconfigurable user I/Os and IEEE 1149.1 compatible with boundary-scan logic for testing and programming. The function test results indicate that the hardware and software cooperate successfully and the VS1000 works correctly. Moreover, the radiation test results indicate that the VS1000 chip has total dose tolerance of 100 krad(Si), a dose rate survivability of 1.5 × 1011 rad(Si)/s and a neutron fluence immunity of 1 × 1014 n/cm2.

  7. General Friction Model Extended by the Effect of Strain Hardening

    Nielsen, Chris V.; Martins, Paulo A.F.; Bay, Niels


    An extension to the general friction model proposed by Wanheim and Bay [1] to include the effect of strain hardening is proposed. The friction model relates the friction stress to the fraction of real contact area by a friction factor under steady state sliding. The original model for the real co...... of friction in metal forming, where the material generally strain hardens. The extension of the model to cover strain hardening materials is validated by comparison to previously published experimental data.......An extension to the general friction model proposed by Wanheim and Bay [1] to include the effect of strain hardening is proposed. The friction model relates the friction stress to the fraction of real contact area by a friction factor under steady state sliding. The original model for the real......-ideally plastic material, and secondly, to extend the solution by the influence of material strain hardening. This corresponds to adding a new variable and, therefore, a new axis to the general friction model. The resulting model is presented in a combined function suitable for e.g. finite element modeling...

  8. Nitrogen hardening of creep-resistant G-NiCr28W alloy

    Z. Pirowski


    Full Text Available In the group of creep-resistant materials, most important are heat-resistant nickel-based alloys. The G-NiCr28W alloy subject to detailed examinations was observed to have two different austenite-like phases. In the interdendritic spaces of alloy matrix, the presence of another phase, also characterised by paramagnetic properties, was detected. Inside this interdendritic phase, local areas of a lamellar structure, composed of both of the above mentioned phases, were present. Nitrogen treatment was observed to raise the microhardness of both these phases.The presence of nitrogen made the regions of a lamellar structure disappear completely. Their place was occupied by precipitates dispersed in the matrix, and occasionally forming large clusters.It has been observed that cold work can harden the G-NiCr28W alloy to a very small degree only, in spite of the fact that hardness isincreasing systematically with the increasing degree of cold work. The said alloy, when enriched with nitrogen added as an alloyingelement, is characterised by hardness higher than the hardness of its nitrogen-free counterpart. The value of hardness is increasing evenmore under the effect of low-degree cold work, although increasing further the degree of cold work seems to have no effect on hardnessincrease. The problem faced in nickel-based materials is the possibility of making defect-free castings from alloys with high nitrogen content. Alloys investigated in the present study were remelted, cast and subject to solidification under high nitrogen pressure in the furnace chamber. However, melting carried out under these conditions could not prevent the occurrence of non-metallic inclusions which, while being unable to pass to a riser, formed local clusters or even thin films, resulting in numerous microcracks or discontinuities encompassing large regions of the casting. This problem seems to be of major concern and is the first one to require prompt solution in the currently

  9. Fruit Morphological Changes during Pit Hardening in Autochthonous Istrian Olive (Olea europaea L. Cultivars

    Marin Krapac


    Full Text Available Endocarp lignification is important fruit growth phenophase since after its completion fruit starts with oil accumulation. The information about duration of endocarp lignification is important for timing of management practices, irrigation and pest control in oil cultivars, and fruit thinning in table cultivars to obtain uniform fruit weight and size. In this study, fruit length, width and weight of four Istrian autochthonous olive cultivars (‘Buža’, ‘Puntoža’, ‘Rošinjola’ and ‘Istarska bjelica’ were measured. Samples were taken from olive collection orchard of the Institute of Agriculture and Tourism in Poreč in equal growing conditions. The aim of the research was to define an olive fruit growth dynamics during pit hardening. Fruit weight in all cultivars was increasing during endocarp lignification (from 7th to 28th July. The highest percentage in the weight growth in the first week had cultivars ‘Buža’ (48.5% and ‘Rošinjola’ (44.6% while in the second week maximum was reached by cultivars ‘Puntoža’ (44.2% and ‘Istarska bjelica’ (42%. The highest increase in total fruit mass was detected in ‘Puntoža’ (1.30 g and the least at ‘Rošinjola’ (0.56 g. Maximum increase in length (L and width (W had ‘Puntoža’ (L: 7.13 mm; W: 4.23 mm and the least ‘Istarska bjelica’ (L: 2.48 mm; W: 2.70 mm.

  10. Changes in Structural Characteristics of Hypoeutectic Al-Si Cast Alloy after Age Hardening



    Full Text Available The contribution describes influence of the age-hardening consist of solution treatment at 515 °C with holding time 4 hours, water quenching at 40 °C and artificial aging at different temperature 150 °C, 170 °C and 190 °C with different holding time 2, 4, 8, 16 and 32 hours on mechanical properties (tensile strength and Brinell hardness and changes in morphology of eutectic Si, Fe-rich and Cu-rich intermetallic phases in secondary (recycled AlSi9Cu3 cast alloy. A combination of different analytical techniques (light microscopy upon black-white and colour etching, scanning electron microscopy (SEM upon deep etching and energy dispersive X-ray analysis (EDX were therefore been used for the identification of the various phases. Quantitative study of changes in morphology of eutectic Si, Cu-rich and Fe-rich phases was carried out using Image Analyzer software NIS-Elements. Mechanical properties were measured in line with EN ISO. Age-hardening led to changes in microstructure include the spheroidization and coarsening of eutectic silicon, gradual disintegration, shortening and thinning of Fe- rich intermetallic phases, the dissolution of precipitates and the precipitation of finer hardening phase (Al2Cu further increase in the hardness and tensile strength in the alloy.DOI:

  11. Ultrasonic testing of the hardening kinetics of epoxy resins used for foundry patterns

    J. Zych


    Full Text Available The study presents the results of investigations on the hardening kinetics of modern pattern materials which, among others, include alsoepoxy resins. Tests were carried out using a new ultrasonic technique developed by the author of the present study. On the example of theEPO 999 resin, the run of the hardening process at temperatures of 10, 20 and 30oC was shown. This is the temperature range appliedduring production of foundry patterns. The time of the preliminary hardening amounted to 800 min at a temperature of 10oC, and to only180 min at a temperature of 30oC. Using ultrasonic technique, the effect of temperature on the modulus of elasticity Ed of the examinedresin was determined. The temperature has been observed to exert a linear effect on the value of the modulus Ed. When the resin pattern is preheated in the range of temperatures from 20 to 50oC, the value of the modulus Ed decreases by 30%. The drop in the value of themodulus Ed, as well as the resin hardness decreasing from 18 to 9,0HB at the increasing temperature reduce the applicability of thismaterial for patterns operating at high temperatures (moulding sands.

  12. Investigation of MWCNT Reinforcement on the Strain Hardening Behavior of Ultrahigh Molecular Weight Polyethylene

    Hassan Mahfuz


    Full Text Available We have investigated strain hardening behavior of ultrahigh molecular weight polyethylene (UHMWPE reinforced with 2.0 wt% loading of multiwalled carbon nanotubes (MWCNTs. A solution spinning process was used to produce neat and MWCNT-reinforced filaments of UHMWPE. Tensile tests of filaments showed 62% and 114% improvement in strength and modulus, respectively. Strain hardening tests on filaments revealed spectacular contribution by MWCNTs in enhancing strength and modulus by more than one order of magnitude. SEM micrographs showed sufficient coating of nanotube surface with the polymer that promoted interface adhesion. This intimate interfacial interaction enforced alignment of nanotubes during repeated loading-unloading sequences and allowed effective load transfer to nanotubes. Close interaction between UHMWPE and nanotubes was further evidenced by Raman spectral distribution as a positive shift in the D-band suggesting compressive stress on nanotubes by lateral compression of polymer. Nanotubes thus deformed induced the desired strain hardening ability in the UHMWPE filament. Differential scanning calorimetry (DSC tests indicated around 15% increase in crystallinity after strain hardening—which together with nanotube alignment resulted in such dramatic improvement in properties.

  13. Monoenergetic computed tomography reconstructions reduce beam hardening artifacts from dental restorations.

    Stolzmann, Paul; Winklhofer, Sebastian; Schwendener, Nicole; Alkadhi, Hatem; Thali, Michael J; Ruder, Thomas D


    The aim of this study was to assess the potential of monoenergetic computed tomography (CT) images to reduce beam hardening artifacts in comparison to standard CT images of dental restoration on dental post-mortem CT (PMCT). Thirty human decedents (15 male, 58 ± 22 years) with dental restorations were examined using standard single-energy CT (SECT) and dual-energy CT (DECT). DECT data were used to generate monoenergetic CT images, reflecting the X-ray attenuation at energy levels of 64, 69, 88 keV, and at an individually adjusted optimal energy level called OPTkeV. Artifact reduction and image quality of SECT and monoenergetic CT were assessed objectively and subjectively by two blinded readers. Subjectively, beam artifacts decreased visibly in 28/30 cases after monoenergetic CT reconstruction. Inter- and intra-reader agreement was good (k = 0.72, and k = 0.73 respectively). Beam hardening artifacts decreased significantly with increasing monoenergies (repeated-measures ANOVA p < 0.001). Artifact reduction was greatest on monoenergetic CT images at OPTkeV. Mean OPTkeV was 108 ± 17 keV. OPTkeV yielded the lowest difference between CT numbers of streak artifacts and reference tissues (-163 HU). Monoenergetic CT reconstructions significantly reduce beam hardening artifacts from dental restorations and improve image quality of post-mortem dental CT.

  14. Cold tolerance and cold hardening strategy of the Japanese pine sawyer Monochamus alternatus (Coleoptera: Cerambycidae)

    Jing Tian; Shu-Guang Hao; Wei-Na Kong; Rui-Yan Ma; Le Kang


    The Japanese pine sawyer, Monochamus alternatus, is an important pine forest pest and vector transmitting the pine wilt nematode that causes pine wilt disease. Low temperatures in autumn, winter and spring often differentially affect mortality of M.alternatus larvae. In this paper, we mainly compared the differences of mortality and cold hardening of larvae from different seasons, based on supercooling point (SCP) and cumulative probability of individuals freezing (CPIF). The cold hardening of the larvae from autumn, winter and spring seasons were largely different. Correlations between mortality and CPIF of autumn and spring larvae were highest on day 1/4, and gradually decreased with prolonged exposure duration. This beetle's death mainly resulted from freezing in short exposure duration. However, the correlation between mortality and CPIF of winter larvae increased gradually with the prolonged exposure duration. Death did not mainly result from freezing in long exposure duration. Autumn larvae are more susceptible and adaptable than winter and spring larvae. Winter larvae have a slight freeze-tolerance trend. Our research showed that M. alternatus came into complex cold-hardening strategies under natural selection. Freeze avoidance is the primary strategy; with prolonged exposure duration to above SCP or < 0℃, chill tolerance is more important; this is followed by freeze tolerance during harsh winters.

  15. Influence of annealing on stain hardening behaviour and fracture properties of a cryorolled Al 2014 alloy

    Dhal, A.; Panigrahi, S.K., E-mail:; Shunmugam, M.S.


    The influence of annealing on strength, ductility, strain hardening, plastic instability and fracture behaviour are studied in the present work on a cryorolled Al 2014 alloy by tensile test, transmission electron microscopy, macrograph analysis and fractography study. Investigations on the cryorolled alloy have been done for different annealing temperatures in the range of 100–400 °C and the results obtained are correlated with the microstructural evolution, precipitation behaviour and post failure analysis. Study reveals a complex trend in ductility and strain hardening behaviour as a result of simultaneous occurrence of dislocation annihilation, recrystallization and precipitation evolution during annealing. By investigations of fractured samples, dominant mode of fracture is found to be shear deformation and upon annealing the fracture mechanism is affected jointly by propagation of microvoids and shear deformation due to combined action of precipitation and microstructural evolution. Yield strength is increased by 4 times after cryorolling and retained after annealing up to 100 °C. It even remains higher than the base material up to 350 °C, due to the combined effect of precipitation hardening and thermal stability of microstructure.

  16. Changes in Structural Characteristics of Hypoeutectic Al-Si Cast Alloy after Age Hardening



    Full Text Available The contribution describes influence of the age-hardening consist of solution treatment at 515 °C with holding time 4 hours, water quenching at 40 °C and artificial aging at different temperature 150 °C, 170 °C and 190 °C with different holding time 2, 4, 8, 16 and 32 hours on mechanical properties (tensile strength and Brinell hardness and changes in morphology of eutectic Si, Fe-rich and Cu-rich intermetallic phases in secondary (recycled AlSi9Cu3 cast alloy. A combination of different analytical techniques (light microscopy upon black-white and colour etching, scanning electron microscopy (SEM upon deep etching and energy dispersive X-ray analysis (EDX were therefore been used for the identification of the various phases. Quantitative study of changes in morphology of eutectic Si, Cu-rich and Fe-rich phases was carried out using Image Analyzer software NIS-Elements. Mechanical properties were measured in line with EN ISO. Age-hardening led to changes in microstructure include the spheroidization and coarsening of eutectic silicon, gradual disintegration, shortening and thinning of Fe- rich intermetallic phases, the dissolution of precipitates and the precipitation of finer hardening phase (Al2Cu further increase in the hardness and tensile strength in the alloy.DOI:

  17. Ultrafine-Grained Precipitation Hardened Copper Alloys by Swaging or Accumulative Roll Bonding

    Igor Altenberger


    Full Text Available There is an increasing demand in the industry for conductive high strength copper alloys. Traditionally, alloy systems capable of precipitation hardening have been the first choice for electromechanical connector materials. Recently, ultrafine-grained materials have gained enormous attention in the materials science community as well as in first industrial applications (see, for instance, proceedings of NANO SPD conferences. In this study the potential of precipitation hardened ultra-fine grained copper alloys is outlined and discussed. For this purpose, swaging or accumulative roll-bonding is applied to typical precipitation hardened high-strength copper alloys such as Corson alloys. A detailed description of the microstructure is given by means of EBSD, Electron Channeling Imaging (ECCI methods and consequences for mechanical properties (tensile strength as well as fatigue and electrical conductivity are discussed. Finally the role of precipitates for thermal stability is investigated and promising concepts (e.g. tailoring of stacking fault energy for grain size reduction and alloy systems for the future are proposed and discussed. The relation between electrical conductivity and strength is reported.

  18. Effect of Mn on hardenability of 25CrMo axle steel by an improved end-quench test

    Zhang Yutuo


    Full Text Available With the sixth large-scale railway speed-up, the quality of the axles is essential to the safety of the locomotive. According to the high-speed axle technical standard for the control of alloy elements in axle steel, optimization experiments of 25CrMo steel composition were performed by vacuum inductive melting. In order to study the hardenability of high-speed rail axles, an improved end-quench test was put forward. The advantage is that it enables the heat to transfer along the axial direction, thus avoiding edge effects. The hardenability of 25CrMo axle steels with Mn content of 0.60wt.% and 0.80wt.% was investigated mainly by means of optical microscopy and hardness tests. The experimental results indicate that the Mn has a pronounced effect on the hardenability of the steel. With an increase in Mn content from 0.60wt.% and 0.80wt.%, the hardenability of 25CrMo axle steel increases and the hard microstructure is maintained at an increasing distance from the quenched end. From the surface of the water quenched end to the center of the sample, the microstructure is martensite, martensite with bainite, and bainite.

  19. Impact toughness of a gradient hardened layer of Cr5Mo1V steel treated by laser shock peening

    Xia, Weiguang; Li, Lei; Wei, Yanpeng; Zhao, Aimin; Guo, Yacong; Huang, Chenguang; Yin, Hongxiang; Zhang, Lingchen


    Laser shock peening (LSP) is a widely used surface treatment technique that can effectively improve the fatigue life and impact toughness of metal parts. Cr5Mo1V steel exhibits a gradient hardened layer after a LSP process. A new method is proposed to estimate the impact toughness that considers the changing mechanical properties in the gradient hardened layer. Assuming a linearly gradient distribution of impact toughness, the parameters controlling the impact toughness of the gradient hardened layer were given. The influences of laser power densities and the number of laser shots on the impact toughness were investigated. The impact toughness of the laser peened layer improves compared with an untreated specimen, and the impact toughness increases with the laser power densities and decreases with the number of laser shots. Through the fracture morphology analysis by a scanning electron microscope, we established that the Cr5Mo1V steel was fractured by the cleavage fracture mechanism combined with a few dimples. The increase in the impact toughness of the material after LSP is observed because of the decreased dimension and increased fraction of the cleavage fracture in the gradient hardened layer.

  20. Modelling changes in nitrogen cycling to sustain increases in forest productivity under elevated atmospheric CO2 and contrasting site conditions

    Grant, R. F.


    If increases in net primary productivity (NPP) caused by rising concentrations of atmospheric CO2 (Ca) are to be sustained, key N processes such as soil mineralization, biological fixation, root uptake and nutrient conservation must also be increased. Simulating the response of these processes to elevated Ca is therefore vital for models used to project the effects of rising Ca on NPP. In this modelling study, hypotheses are proposed for changes in soil mineralization, biological fixation, root nutrient uptake and plant nutrient conservation with changes in Ca. Algorithms developed from these hypotheses were tested in the ecosystem model ecosys against changes in N and C cycling measured over several years under ambient vs. elevated Ca in Free Air CO2 Enrichment (FACE) experiments in the USA at the Duke Forest in North Carolina, the Oak Ridge National Laboratory forest in Tennessee, and the USDA research forest in Wisconsin. More rapid soil N mineralization was found to be vital for simulating sustained increases in NPP measured under elevated vs. ambient Ca at all three FACE sites. This simulation was accomplished by priming decomposition of N-rich humus from increases in microbial biomass generated by increased litterfall modelled under elevated Ca. Greater nonsymbiotic N2 fixation from increased litterfall, root N uptake from increased root growth, and plant N conservation from increased translocation under elevated Ca were found to make smaller contributions to simulated increases in NPP. However greater nutrient conservation enabled larger increases in NPP with Ca to be modelled with coniferous vs. deciduous plant functional types. The effects of these processes on productivity now need to be examined over longer periods under transient rises in Ca and a greater range of site conditions.

  1. A Combined Isotropic, Kinematic and Cross Hardening Model for Magnesium AZ31B-H24 under Non-linear Strain Loading Path

    Jia, Yueqian; Bai, Yuanli


    A fully modularized framework was established to combine isotropic, kinematic, and cross hardening behaviors under non-monotonic loading conditions. Three sets of state variables were defined and applied to consider the effects of, a) loading history, b) twinning and de-twinning and c) different pre-strain. Experiments under two types of non-proportional loading conditions were conducted along different orientations, 1) uniaxial compression-tension reversal loading with different amounts of compressive strains, and 2) two-step uniaxial tension, known as cross-loading conditions, with different pre-strains. No apparent cross-hardening effect was observed for this material. The calibrated new hardening model, with an anisotropic CPB06ex2 yield criterion and an eMMC anisotropic fracture model, has been implemented into Abaqus/ Explicit as a user material subroutine (VUMAT). Good correlation was observed between experimental and simulation results.

  2. Increasing incidence of statin treatmentamong the elderly and those withoutprevious cardiovascular conditions. A nationwide register study

    Kildemoes, Helle Wallach; Andersen, Morten

    for the increasing Danish statin utilization during 1996-2005, applying treatment incidence as a measure of changing prescribing behaviour Methods: Applying three nationwide registers, we followed Danish inhabitants with respect to demographics, dispensed prescriptions of cardiovascular drugs and antidiabetics along...... with discharge diagnoses and surgical procedures performed during 1977-2005. The disease status for all cohort members was assigned by means of disease markers for seven cardiovascular conditions, corresponding to a hierarchy of broad indications for statin therapy. Using the indication hierarchy, we computed...... treatment incidence of statins each year stratifying by indication, age and gender. We estimated the overall and age/indication specific increases in incidence as incidence Rate Ratios (IRR) with 95% confidence interval (CI), using Poisson regression analyses. Results: Treatment incidence increased from 4...

  3. Increased molecular mass of hemicellulosic polysaccharides is involved in growth inhibition of maize coleoptiles and mesocotyls under hypergravity conditions.

    Soga, K; Harada, K; Wakabayashi, K; Hoson, T; Kamisaka, S


    Elongation growth of dark grown maize (Zea mays L cv. Cross Bantam T51) coleoptiles and mesocotyls was suppressed by hypergravity at 30 g and above. Acceleration at 300 g significantly decreased the mechanical extensibility of cell walls of both organs. Hypergravity increased the amounts of hemicellulose and cellulose per unit length in mesocotyl walls, but not in coleoptile walls. The weight average molecular masses of hemicellulosic polysaccharides were also increased by hypergravity in both organs. On the other hand, the activities of beta-glucanases extracted from coleoptile and mesocotyl cell walls were decreased by hypergravity. These results suggest that the decreased activities of beta-glucanases by hypergravity cause an increase in the molecular mass of hemicellulosic polysaccharides of both organs. The upshift of molecular mass of hemicellulosic polysaccharides as well as the thickening of cell walls under hypergravity conditions seems to be involved in making the cell wall mechanically rigid, thereby inhibiting elongation growth of maize coleoptiles and mesocotyls.

  4. Food-aversive classical conditioning increases a persistent sodium current in molluscan withdrawal interneurons in a transcription dependent manner.

    Kiss, Tibor; Pirger, Zsolt; Kemenes, György


    In this study we examined changes in a persistent sodium current (I(NaP)) after behavioral aversive classical conditioning in the snail Helix pomatia. We trained animals by pairing food with a mild electric shock that triggered the whole-body withdrawal reflex. This aversive training resulted in transcription dependent long-term associative memory. Isolated central nervous system preparations were set up from trained, random control and naive animals and using two-electrode voltage clamp methods, I(NaP) was activated and measured in identified body withdrawal interneurons RPa3 and LPa3. We show here that in preparations from conditioned animals I(NaP) is increased, suggesting that modifications in intrinsic cellular properties contribute to the formation of the memory trace. Blocking RNA synthesis by systemic injection of actinomycin D (0.12microM) suppressed both memory consolidation in intact animals and the learning-induced increase of I(NaP) in withdrawal interneurons, suggesting that aversive classical conditioning affects sodium channel expression at the transcriptional level.

  5. Increasing nest predation will be insufficient to maintain polar bear body condition in the face of sea ice loss.

    Dey, Cody J; Richardson, Evan; McGeachy, David; Iverson, Samuel A; Gilchrist, Hugh G; Semeniuk, Christina A D


    Climate change can influence interspecific interactions by differentially affecting species-specific phenology. In seasonal ice environments, there is evidence that polar bear predation of Arctic bird eggs is increasing because of earlier sea ice breakup, which forces polar bears into nearshore terrestrial environments where Arctic birds are nesting. Because polar bears can consume a large number of nests before becoming satiated, and because they can swim between island colonies, they could have dramatic influences on seabird and sea duck reproductive success. However, it is unclear whether nest foraging can provide an energetic benefit to polar bear populations, especially given the capacity of bird populations to redistribute in response to increasing predation pressure. In this study, we develop a spatially explicit agent-based model of the predator-prey relationship between polar bears and common eiders, a common and culturally important bird species for northern peoples. Our model is composed of two types of agents (polar bear agents and common eider hen agents) whose movements and decision heuristics are based on species-specific bioenergetic and behavioral ecological principles, and are influenced by historical and extrapolated sea ice conditions. Our model reproduces empirical findings that polar bear predation of bird nests is increasing and predicts an accelerating relationship between advancing ice breakup dates and the number of nests depredated. Despite increases in nest predation, our model predicts that polar bear body condition during the ice-free period will continue to decline. Finally, our model predicts that common eider nests will become more dispersed and will move closer to the mainland in response to increasing predation, possibly increasing their exposure to land-based predators and influencing the livelihood of local people that collect eider eggs and down. These results show that predator-prey interactions can have nonlinear responses to

  6. The response of mulberry trees after seedling hardening to summer drought in the hydro-fluctuation belt of Three Gorges Reservoir Areas.

    Huang, Xiaohui; Liu, Yun; Li, Jiaxing; Xiong, Xingzheng; Chen, Yang; Yin, Xiaohua; Feng, Dalan


    Interest has developed in the potential of mulberry (Morus alba), a woody perennial, for revegetating the hydro-fluctuation belt of the Three Gorges Reservoir due to its resistance to water-logging stress. To be useful, the trees must also be able to withstand dry conditions in summer when temperatures can be very high and droughts become severe quickly. Here, we report a study in which mulberry seedlings were grown in a greenhouse under a variety of simulated soil water conditions reflecting potential summer scenarios in the hydro-fluctuation belt of the Three Gorges Reservoir Area. We compared the responses of two pretreatment groups of mulberry seedlings to different levels of drought stress. The pretreatment groups differed with respect to drought hardening: the daily-managed (DM) group had relative soil moisture held constant in the range 70-80 %, while the drought-hardened (DH) group had relative soil moisture held constant at 40-50 %. Following the month-long pretreatment of seedlings, the two groups of young trees (DM and DH) were then respectively subjected to three levels of drought stress for a month: normal watering, moderate drought stress, and severe drought stress. A series of measurements comparing the physiological status of the plants in the two groups were then made, and the following results were obtained: (1) As drought stress increased, the heights, base diameters, root surface areas, photosynthetic rates (Pn), stomatal conductances (Gs), and transpiration rates (Tr) of the mulberry trees in both groups (DM and DH) decreased significantly, while the specific root area and abscisic acid (ABA) contents had increasing trends. Root activity and instantaneous water use efficiency of mulberry trees in both groups (DM and DH) were all raised under drought stress conditions than under normal watering, but the root/shoot ratio and leaf water potential were lowered. (2) At the same level of soil water content, the heights, base diameters, root

  7. Surface hardening of steel in a solar furnace

    Rodriguez, G.P. [UCLM, ETSII, Ciudad Real (Spain); Damborenea, J.J. de [CENIM-CSIC, Madrid (Spain); Vazquez, A.J. [CENIM-CSIC, Madrid (Spain)


    The concentration of solar energy provides the possibility to get power densities high enough to produce surface modifications of materials, with low environmental impact. The present paper discusses the possibilities of surface hardening steel by means of concentrated solar energy. Surface treatments have been made by using the solar furnace of the Platafoma Solar in Almeria (Spain), which consists of a group of heliostats and a parabolic mirror. The surface transformation hardening treatment was performed on a 40CrMo4 steel. The paper presents the microstructural changes and the hardness values obtained after the solar treatment in a superficial zone. According to the power density applied on the sample, the hardened zone varied between 1 and 10 mm deep and the treatment time was less than 30 s. (orig.)

  8. Influence of coolant motion on structure of hardened steel element

    A. Kulawik


    Full Text Available Presented paper is focused on volumetric hardening process using liquid low melting point metal as a coolant. Effect of convective motion of the coolant on material structure after hardening is investigated. Comparison with results obtained for model neglecting motion of liquid is executed. Mathematical and numerical model based on Finite Element Metod is described. Characteristic Based Split (CBS method is used to uncouple velocities and pressure and finally to solve Navier-Stokes equation. Petrov-Galerkin formulation is employed to stabilize convective term in heat transport equation. Phase transformations model is created on the basis of Johnson-Mehl and Avrami laws. Continuous cooling diagram (CTPc for C45 steel is exploited in presented model of phase transformations. Temporary temperatures, phases participation, thermal and structural strains in hardening element and coolant velocities are shown and discussed.

  9. Neutron-irradiation + helium hardening and embrittlement modeling of 9% Cr-steels in an engineering perspective (HELENA)

    Chaouadi, Rachid


    This report provides a physically-based engineering model to estimate the radiation hardening of 9%Cr-steels under both displacement damage (dpa) and helium. The model is essentially based on the dispersed barrier hardening theory and the dynamic re-solution of helium under displacement cascades. However, a number of assumptions and simplifications were considered to obtain a simple description of irradiation hardening and embrittlement primarily relying on the available experimental data. As a result, two components were basically identified, the dpa component that can be associated with black dots and small loops and the He-component accounting for helium bubbles. The dpa component is strongly dependent on the irradiation temperature and its dependence law was based on a first-order annealing kinetics. The damage accumulation law was also modified to take saturation into account. Finally, the global kinetics of the damage accumulation kept defined, its amplitude is fitted to one experimental condition. The model was rationalized on an experimental database that mainly consists of {proportional_to}9%Cr-steels irradiated in the technologically important temperature range of 50 to 600 C up do 50 dpa and with a He-content up to {proportional_to}5000 appm, including neutron and proton irradiation as well as implantation. The test temperature effect is taken into account through a normalization procedure based on the change of the Young's modulus and the anelastic deformation that occurs at high temperature. Finally, the hardening-to-embrittlement correlation is obtained using the load diagram approach. Despite the large experimental scatter, inherent to the variety of the materials and irradiation as well as testing conditions, the obtained results are very promising. Improvement of the model performance is still possible by including He-hardening saturation and high temperature softening but unfortunately, at this stage, a number of conflicting experimental data

  10. Increased body condition score through increased lean muscle, but not fat deposition, is associated with reduced reproductive response to oestrus induction in beef cows.

    Guzmán, A; Gonzalez-Padilla, E; Garcés-Yepez, P; Rosete-Fernández, J V; Calderón-Robles, R C; Whittier, W D; Keisler, D H; Gutierrez, C G


    Energy reserve, estimated as body condition score (BCS), is the major determinant of the re-initiation of ovarian activity in postpartum cows. Leptin, IGF-I and insulin are positively related to BCS and are putative mediators between BCS and reproductive function. However, when BCS and body composition dissociates, concentrations of these metabolic hormones are altered. We hypothesized that increasing lean muscle tissue, but not fat tissue, would diminish the reproductive response to oestrus induction treatments. Thirty lactating beef cows with BCS of 3.10±1.21 and 75.94±12 days postpartum were divided in two groups. Control cows (n=15) were supplemented with 10.20 kg of concentrate daily for 60 days. Treated cows (n=15) were supplemented equally, and received a β-adrenergic receptor agonist (β-AA; 0.15 mg/kg BW) to achieve accretion of lean tissue mass and not fat tissue mass. Twelve days after ending concentrate supplementation/β-AA treatment, cows received a progestin implant to induce oestrus. Cows displaying oestrus were inseminated during the following 60 days, and maintained with a fertile bull for a further 21 days. Cows in both groups gained weight during the supplementation period (Daily weight gain: Control=0.75 kg v. β-AA=0.89 kg). Cows treated with β-AA had a larger increase in BCS (i.e. change in BCS: control=1 point (score 4.13) v. β-AA=2 points (score 5.06; P0.05) did not differ between groups. However, the number of cows displaying oestrus (control 13/15 v. β-AA 8/15; Pincrease BCS through muscle tissue accretion, but not through fat tissue accretion, resulted in a lower response to oestrus induction, lower percentage of cycling animals and lower pregnancy percentage after progestin treatment; which was associated with a decrease in serum concentrations of leptin and IGF-I.


    Maman Turjaman


    Full Text Available Gaharu wood stand has an important source of profits to the forest community in South and Southeast Asia tropical forest countries, but Aquilaria species have reduced in number and turn out to be endangered due to overexploitation.   Today,   the planting stocks of   Aquilaria species are not sufficient to sustain the yield of gaharu wood and promote forest conservation.  The objective of this study was to determine   the effect of   five arbuscular mycorrhizal (AM fungi: Entrophospora sp., Gigaspora decipiens, Glomus clarum, Glomus sp. ZEA, and Glomus sp. ACA, on the early growth of  Aquilaria malaccensis and A. crasna under greenhouse conditions. The seedlings of  Aquilaria spp. were inoculated with Entrophospora sp., Gi. decipiens, Glomus clarum, Glomus sp. ZEA, Glomus sp. ACA and uninoculated (control under greenhouse conditions. Then, percentage AM colonization, plant growth, survival rate and nitrogen (N and phosphorus (P content and mycorrhizal dependence (MD were measured. The percentage AM colonization of A. malaccensis and A. crasna ranged from 83 to 97% and from 63 to 78%, respectively. Colonization by five AM fungi increased plant height, diameter, and shoot and root dry weights. N and P content of  the seedlings were also increased by AM colonization. Survival rates were higher in the AM-colonized seedlings at 180 days after transplantation than those in the control seedlings. The MD of Aquilaria species was higher than 55 %. The results suggested that AM fungi can be inoculated`to Aquilaria species under nursery conditions to obtain vigorous seedlings, and the field experiment is underway to clarify the role of AM fungi under field conditions.

  12. Arbuscular mycorrhizal fungi increased early growth of two nontimber forest product species Dyera polyphylla and Aquilaria filaria under greenhouse conditions.

    Turjaman, Maman; Tamai, Yutaka; Santoso, Erdy; Osaki, Mitsuru; Tawaraya, Keitaro


    Nontimber forest products (NTFPs) represent an important source of income to millions of people in tropical forest regions, but some NTFP species have decreased in number and become endangered due to overexploitation. There is increasing concern that the planting stocks of Dyera polyphylla and Aquilaria filaria are not sufficient to sustain the yield of NTFPs and promote forest conservation. The objective of this study was to determine the effect of two arbuscular mycorrhizal (AM) fungi, Glomus clarum and Gigaspora decipiens, on the early growth of two NTFP species, D. polyphylla and A. filaria, under greenhouse conditions. The seedlings of both species were inoculated with G. clarum or G. decipiens, or uninoculated (control) under greenhouse conditions. Percentage of AM colonization, plant growth, survival rate, and nitrogen (N) and phosphorus (P) concentrations were measured after 180 days of growth. The percentage of AM colonization of D. polyphylla and A. filaria ranged from 87 to 93% and from 22 to 39%, respectively. Colonization by G. clarum and G. decipiens increased plant height, diameter, and shoot and root dry weights. Shoot N and P concentrations of the seedlings were increased by AM colonization by as much as 70-153% and 135-360%, respectively. Survival rates were higher in the AM-colonized seedlings at 180 days after transplantation than in the control seedlings. The results suggest that AM fungi can accelerate the establishment of the planting stocks of D. polyphylla and A. filaria, thereby promoting their conservation ecologically and sustaining the production of these NTFPs economically.

  13. [Responses of Arma chinensis cold tolerance to rapid cold hardening and underlying physiological mechanisms].

    Li, Xing-Peng; Song, Li-Wen; Zhang, Hong-Hao; Chen, Yue-Qu; Zuo, Tong-Tong; Wang, Jun; Sun, Wei


    Rapid cold hardening can enhance the cold tolerance of some insects. To explore the effects of different cold hardening induction temperature on the cold tolerance of Arma chinensis and related physiological mechanisms, the 3rd generation A. chinensis adults reared indoor were treated with cooling at 15, 10, and 4 degrees C for 4 h, respectively, or with gradual cooling from 15 degrees C for 4 h to 10 degrees C for 4 h, and finally to 4 degrees C for 4 h. The super-cooling point, water content, and the contents of low molecular carbohydrates, glycerol, and amino acids of the adults after cooling and the adults cold tolerance at 0, -5, and -10 degrees C were measured by thermocouple, high performance liquid chromatography, and other analytical techniques. When exposed at -10 degrees C after cooling, the survival rate of the adults treated with gradual cooling or treated with cooling at 4 degrees C for 4 h was averagely 58.3%, while that of the adults reared at room temperature (25 degrees C +/- 2 degrees C) or treated with cooling at 15 degrees C or 10 degrees C for 4 h decreased significantly, with an average of 8.9%. The super-cooling point of the adults treated with gradual cooling or with cooling at 4 degrees C for 4 h was -15.6 degrees C, which was averagely 1.3 degrees C lower than that of the other treatments. The water content of the adults had no significant difference among all treatments, with an average of 61.8%, but the glucose, sorbitolum, glycerol, Ala, and Glu contents in treatments gradual cooling and cooling at 4 degrees C for 4 h increased by 2.82-fold, 2.65-fold, 3.49-fold, 51.3%, and 80.2%, while the fucose, mannose, and Pro contents decreased by 68.4%, 52.2%, and 30.2%, respectively, as compared with the other treatments. The fructose content showed no significant difference among all treatments. It was suggested that rapid cool hardening had a critical temperature to induce the physiological metabolism process of adult A. chinensis, and


    E. P. Baradyntseva


    Full Text Available The research conducted in laboratory of metallurgical science by which the factors exerting impact on hardenability of steel microalloyed by boron were analysed. The research was made because the implementation of this process in mass production is connected with the certain difficulties. The conducted researches have allowed to draw a conclusion that changing content of various chemical elements, such as nitrogen, boron, the titan and aluminum in steel containing boron, produced by JSC «BSW – Management Company of Holding «BMC» at the stage of preparation of chart flowsheet make it possible to predict terms of hardenability of the final product.

  15. Aspect-oriented security hardening of UML design models

    Mouheb, Djedjiga; Pourzandi, Makan; Wang, Lingyu; Nouh, Mariam; Ziarati, Raha; Alhadidi, Dima; Talhi, Chamseddine; Lima, Vitor


    This book comprehensively presents a novel approach to the systematic security hardening of software design models expressed in the standard UML language. It combines model-driven engineering and the aspect-oriented paradigm to integrate security practices into the early phases of the software development process. To this end, a UML profile has been developed for the specification of security hardening aspects on UML diagrams. In addition, a weaving framework, with the underlying theoretical foundations, has been designed for the systematic injection of security aspects into UML models. The

  16. Laser hardening processing on tool steel SKD61



    This paper is aimed at overcoming different degree defects of crystalline structure in SKD61 carbide tool steel under quenching in solid phase and liquid phase. The paper studies the micro-structure and properties of laser strengthening SKD61 by using the method of laser hardening on the rein-forcement to improve the wear resistance of SKD61 . The results showed that the laser strengthening meth-od can improve the wear resistance of SKD61 . The study can provide reference for laser hardening metal materials.

  17. Microstructure and properties of cast iron after laser surface hardening



    Full Text Available Laser surface hardening of cast iron is not trivial due to the material’s heterogeneity and coarse-grained microstructure, particularly in massive castings. Despite that, hardening of heavy moulds for automotive industry is in high demand. The present paper summarises the findings collected over several years of study of materials structure and surface properties. Phase transformations in the vicinity of graphite are described using examples from production of body parts in automotive industry. The description relates to formation of martensite and carbide-based phases, which leads to hardness values above 65 HRC and to excellent abrasion resistance.


    P. V. Voronov


    Full Text Available Problem statement. Kinetic processes are of huge importance when producing building units and operating them as well. However, both technological and operation parameters are determined by the structure of a material under study.Results and conclusions. Kinetics with asymptotic approximation at hardening of building materials is analyzed. The validity of use of new kinetic equation is proved, characterizing harden composite systems and taking into consideration structural and topological peculiarities of new solid-like phase formation directly effecting the evolution of the processes. Results of research of change of strength at solidification a cement-sandy solution with various additives are submitted.

  19. Radiation Hardened 10BASE-T Ethernet Physical Layer (PHY)

    Lin, Michael R. (Inventor); Petrick, David J. (Inventor); Ballou, Kevin M. (Inventor); Espinosa, Daniel C. (Inventor); James, Edward F. (Inventor); Kliesner, Matthew A. (Inventor)


    Embodiments may provide a radiation hardened 10BASE-T Ethernet interface circuit suitable for space flight and in compliance with the IEEE 802.3 standard for Ethernet. The various embodiments may provide a 10BASE-T Ethernet interface circuit, comprising a field programmable gate array (FPGA), a transmitter circuit connected to the FPGA, a receiver circuit connected to the FPGA, and a transformer connected to the transmitter circuit and the receiver circuit. In the various embodiments, the FPGA, transmitter circuit, receiver circuit, and transformer may be radiation hardened.

  20. Effect on Hydration and Hardening of Tricalcium Phosphate Bone Cement


    The bioactive α-Ca3 (PO4)2 bone cement was studied by XRD , SEM and isothermal calorimetric measurements. The results showed that a mixed pattern of TCP and hydroxylapatite were obtained after hydration and hardening. The mechanism of hydration and hardening of the α-Ca3 ( PO4 )2 was dissolution-precipitation,(NH4) H2 PO4 was the best set accelerator to the α-Ca3 ( PO4 )2 cement, and the HAP powers and the(NH4) H2 PO4 concentration had a great effect on the hydration rate of α-Ca3 ( PO4 )2.

  1. Impact of Scaled Technology on Radiation Testing and Hardening

    LaBel, Kenneth A.; Cohn, Lewis M.


    This presentation gives a brief overview of some of the radiation challenges facing emerging scaled digital technologies with implications on using consumer grade electronics and next generation hardening schemes. Commercial semiconductor manufacturers are recognizing some of these issues as issues for terrestrial performance. Looking at means of dealing with soft errors. The thinned oxide has indicated improved TID tolerance of commercial products hardened by "serendipity" which does not guarantee hardness or say if the trend will continue. This presentation also focuses one reliability implications of thinned oxides.

  2. Temperature influence on water transport in hardened cement pastes

    Drouet, Emeline [CEA, DEN, DPC, SECR, Laboratoire d' Etude du Comportement des Bétons et des Argiles, F-91191 Gif sur Yvette Cedex (France); Poyet, Stéphane, E-mail: [CEA, DEN, DPC, SECR, Laboratoire d' Etude du Comportement des Bétons et des Argiles, F-91191 Gif sur Yvette Cedex (France); Torrenti, Jean-Michel [Université Paris-Est, IFSTTAR, Département Matériaux & Structures, 14-52 boulevard Newton, F-77447 Marne la Vallée cedex 2 (France)


    Describing water transport in concrete is an important issue for the durability assessment of radioactive waste management reinforced concrete structures. Due to the waste thermal output such structures would be submitted to moderate temperatures (up to 80 °C). We have then studied the influence of temperature on water transport within hardened cement pastes of four different formulations. Using a simplified approach (describing only the permeation of liquid water) we characterized the properties needed to describe water transport (up to 80 °C) using dedicated experiments. For each hardened cement paste the results are presented and discussed.

  3. A rapid cold-hardening process in insects.

    Lee, R E; Chen, C P; Denlinger, D L


    Traditionally studies of cold tolerance in insects have focused on seasonal adaptations related to overwintering that are observed after weeks or months of exposure to low temperature. In contrast, an extremely rapid cold-hardening response was observed in nonoverwintering stages that confers protection against injury due to cold shock at temperatures above the supercooling point. This response was observed in nondiapausing larvae and pharate adults of the flesh fly, Sarcophaga crassipalpis, nondiapausing adults of the elm leaf beetle, Xanthogaleruca luteola, and the milkweed bug, Oncopeltus fasciatus. The rapid hardening response is correlated with the accumulation of glycerol.

  4. Increase on the initial soluble heme levels in acidic conditions is an important mechanism for spontaneous heme crystallization in vitro.

    Renata Stiebler

    Full Text Available BACKGROUND: Hemozoin (Hz is a heme crystal that represents a vital pathway for heme disposal in several blood-feeding organisms. Recent evidence demonstrated that β-hematin (βH (the synthetic counterpart of Hz formation occurs under physiological conditions near synthetic or biological hydrophilic-hydrophobic interfaces. This seems to require a heme dimer acting as a precursor of Hz crystals that would be formed spontaneously in the absence of the competing water molecules bound to the heme iron. Here, we aimed to investigate the role of medium polarity on spontaneous βH formation in vitro. METHODOLOGY/PRINCIPAL FINDINGS: We assessed the effect of water content on spontaneous βH formation by using the aprotic solvent dimethylsulfoxide (DMSO and a series of polyethyleneglycols (PEGs. We observed that both DMSO and PEGs (3.350, 6.000, 8.000, and 22.000 increased the levels of soluble heme under acidic conditions. These compounds were able to stimulate the production of βH crystals in the absence of any biological sample. Interestingly, the effects of DMSO and PEGs on βH formation were positively correlated with their capacity to promote previous heme solubilization in acidic conditions. Curiously, a short chain polyethyleneglycol (PEG 300 caused a significant reduction in both soluble heme levels and βH formation. Finally, both heme solubilization and βH formation strongly correlated with reduced medium water activity provided by increased DMSO concentrations. CONCLUSIONS: The data presented here support the notion that reduction of the water activity is an important mechanism to support spontaneous heme crystallization, which depends on the previous increase of soluble heme levels.

  5. Method of Electrolyte-Plasma Surface Hardening of 65G and 20GL Low-Alloy Steels Samples

    Rakhadilov, Bauyrzhan; Zhurerova, Laila; Pavlov, Alexander


    This work is devoted to formation of modified surface layers in 65G and 20GL steels which using for the manufacture of railway transport parts, as well as the study of influence of the parametersof electrolyte-plasma surface hardening methodon the changes in structural-phase states, improving of wear-resistance. The process of electrolyte-plasma surface hardening of 65G and 20GL steels samples conducted in the electrolyte from water solution of 20% sodium carbonate, in the mode ~850°C - 2 seconds, ∼⃒1200°C - 3 seconds. It is established that in the initial state 20GL steel has ferrite-pearlite structure, and the 60G steel consists of pearlite and cement structure. After application of electrolyte-plasma surface hardening is observed the formation of carbides particles and martensite phase components in the structure of 20GL and 60G steels. It is determined that after electrolyte-plasma surface hardening with heating time - 2 seconds, the abrasive wear-resistance of 65G and 20GL steels increased to 1.3 times and 1.2 times, respectively, and the microhardness is increased to 1.6 times and 1.3 times, respectively.

  6. Modelling changes in nitrogen cycling to sustain increases in forest productivity under elevated atmospheric CO2 and contrasting site conditions

    R. F. Grant


    Full Text Available If increases in net primary productivity (NPP caused by rising concentrations of atmospheric CO2 (Ca are to be sustained, key N processes such as soil mineralization, biological fixation, root uptake and plant translocation must be hastened. Simulating the response of these processes to elevated Ca is therefore vital for models used to project the effects of rising Ca on NPP. In this modelling study, hypotheses are proposed for changes in soil mineralization, biological fixation, root uptake and plant translocation with changes in Ca. Algorithms developed from these hypotheses were tested in the ecosystem model ecosys against changes in N and C cycling measured over several years under ambient vs. elevatedCa in Free Air CO2 Enrichment (FACE experiments at the Duke Forest in North Carolina, the Oak Ridge National Laboratory forest in Tennessee, and the USDA research forest in Wisconsin, USA. Simulating more rapid soil N mineralization was found to be vital for modelling sustained increases in NPP measured under elevated vs. ambient Ca at all three FACE sites. This simulation was accomplished by priming decomposition of N-rich humus from increases in microbial biomass generated by increased litterfall modelled under elevated Ca. Simulating more rapid nonsymbiotic N2 fixation, root N uptake and plant N translocation under elevated Ca was found to make much smaller contributions to modelled increases in NPP, although such contributions might be greater over longer periods and under more N-limited conditions than those simulated here. Greater increases in NPP with Ca were also modelled with increased temperature and water stress, and with coniferous vs. deciduous plant functional types. These increases were also associated with changes in N cycling.

  7. Age-hardening characteristic of an Al-Zn-Mg-Cu alloy produced by spray deposition

    WANG Feng; XIONG Baiqing; ZHANG Yongan; ZHU Baohong; LIU Hongwei; ZHANG Zhihui; WANG Zixing


    Al-10.8Zn-2.8Mg-1.9Cu alloy was synthesized by spray atomization and deposition technique. GP zones and age-hardening process in the alloy were investigated using high-resolution electron microscopy (HREM), selected area diffraction (SAD), and differential scanning calorimetry (DSC) analysis. The results indicated that spray deposition process accelerated the aging kinetics of the alloy at an aging temperature of 120℃, thereby reducing the peak aging time to 16 h.GPI and GPⅡ are the two types of zones that are major precipitates for the alloy under peak-aged condition. The precipitation sequence for the alloy is also discussed.

  8. Characterization of cracking in Strain-Hardening Cementitious Composites using the compact tension test

    Pereira, Eduardo B.; Fischer, Gregor; Barros, Joaquim A. O.

    The characterization of the tensile behavior of strain hardening cementitious composites (SHCC) is of significant importance to the material design. In a previous work the tensile stress-crack opening response of different types of SHCC was characterized using notched specimens tested in direct...... plate specimens and the eccentrically applied tensile load create the local conditions necessary to the initiation of a single crack at the tip of the notch. Further propagation and opening of the crack in Mode I allow the assessment of the tensile load-displacement relationship. The experimental...

  9. Chloride diffusivity in hardened cement paste from microscale analyses and accounting for binding effects

    Carrara, P.; De Lorenzis, L.; Bentz, D. P.


    The diffusion of chloride ions in hardened cement paste (HCP) under steady-state conditions and accounting for the highly heterogeneous nature of the material is investigated. The three-dimensional HCP microstructures are obtained through segmentation of x-ray images of real samples as well as from simulations using the cement hydration model CEMHYD3D. Moreover, the physical and chemical interactions between chloride ions and HCP phases (binding), along with their effects on the diffusive process, are explicitly taken into account. The homogenized diffusivity of the HCP is then derived through a least square homogenization technique. Comparisons between numerical results and experimental data from the literature are presented.

  10. Microstructure-property relationships and constitutive response of plastically graded case hardened steels

    Klecka, Michael A.

    Case hardened materials, popularly used in many demanding engineering applications such as bearings, gears, and wear/impact surfaces, have high surface hardness and a gradient in material properties (hardness, yield strength, etc.) as a function of depth; therefore, they behave as plastically graded materials. In the current study, two different commercially available case carburized steels along with two through hardened steels are characterized to obtain relationships among the volume fraction of subsurface carbides, indentation hardness, elastic modulus, and yield strength as a function of depth. A variety of methods including microindentation, nanoindentation, ultrasonic measurements, compression testing, rule of mixtures, and upper and lower bound models are used to determine the relationships for elastic modulus and compare the experimental results with model predictions. In addition, the morphology, composition, and properties of the carbide particles are also determined. The gradient in hardness with depth in graded materials is commonly determined using microindentation on the cross-section of the material which contains the gradation in microstructure or composition. In the current study, a novel method is proposed to predict the hardness gradient profile using solely surface indentations at a range of loads. The method does not require the graded material to be sectioned, and has practical utility in the surface heat-treatment industry. For a material with a decreasing gradient in hardness, higher indent loads result in a lower measured hardness due to the influence of the softer subsurface layers. A power-law model is presented which relates the measured surface indentation hardness under increasing load to the subsurface gradient in hardness. A coordinated experimental and numerical study is presented to extract the constitutive response of graded materials, utilizing relationships between hardness, plastic deformation, and strain hardening response

  11. Increased extracellular matrix density decreases MCF10A breast cell acinus formation in 3D culture conditions.

    Lance, Amanda; Yang, Chih-Chao; Swamydas, Muthulekha; Dean, Delphine; Deitch, Sandy; Burg, Karen J L; Dréau, Didier


    The extracellular matrix (ECM) contributes to the generation and dynamic of normal breast tissue, in particular to the generation of polarized acinar and ductal structures. In vitro 3D culture conditions, including variations in the composition of the ECM, have been shown to directly influence the formation and organization of acinus-like and duct-like structures. Furthermore, the density of the ECM appears to also play a role in the normal mammary tissue and tumour formation. Here we show that the density of the ECM directly influences the number, organization and function of breast acini. Briefly, non-malignant human breast MCF10A cells were incubated in increasing densities of a Matrigel®-collagen I matrix. Elastic moduli near and distant to the acinus structures were measured by atomic force microscopy, and the number of acinus structures was determined. Immunochemistry was used to investigate the expression levels of E-cadherin, laminin, matrix metalloproteinase-14 and ß-casein in MCF10A cells. The modulus of the ECM was significantly increased near the acinus structures and the number of acinus structures decreased with the increase in Matrigel-collagen I density. As evaluated by the expression of laminin, the organization of the acinus structures present was altered as the density of the ECM increased. Increases in both E-cadherin and MMP14 expression by MCF10A cells as ECM density increased were also observed. In contrast, MCF10A cells expressed lower ß-casein levels as the ECM density increased. Taken together, these observations highlight the key role of ECM density in modulating the number, organization and function of breast acini.

  12. Higher Water Temperature and Incubation under Aerobic and Microaerobic Conditions Increase the Recovery and Diversity of Arcobacter spp. from Shellfish

    Levican, Arturo; Collado, Luis; Yustes, Clara; Aguilar, Carme


    Some Arcobacter species are considered emerging food-borne and waterborne pathogens, and shellfish have been suggested as one of their reservoirs. However, only a few studies have investigated the presence of Arcobacter in this kind of food. This study assesses the prevalence and diversity of Arcobacter spp. in shellfish by multiplex PCR (m-PCR) and culturing methods (under different atmospheric conditions) and evaluates the possible influence of environmental parameters (temperature, salinity, and harvesting bay). Arcobacter was detected by m-PCR and/or culturing in 61 (29.9%) of 204 shellfish samples. Of the positive samples by culturing, 41.1% were obtained under only aerobic incubation conditions, while 23.2% were obtained under only microaerobic conditions. Of 476 investigated isolates, 118 belonged to different enterobacterial repetitive intergenic consensus (ERIC)-PCR genotypes (strains) and to 11 different species. This study shows the highest diversity of Arcobacter species ever observed in samples from any origin. The most prevalent species was Arcobacter butzleri (60.2%), followed by Arcobacter molluscorum (21.2%). The prevalence of Arcobacter was significantly higher during the summer than in other seasons, being associated with an increase in water temperature. Results confirm that shellfish are a reservoir for a remarkable diversity of Arcobacter spp. PMID:24185851

  13. Higher water temperature and incubation under aerobic and microaerobic conditions increase the recovery and diversity of Arcobacter spp. from shellfish.

    Levican, Arturo; Collado, Luis; Yustes, Clara; Aguilar, Carme; Figueras, Maria José


    Some Arcobacter species are considered emerging food-borne and waterborne pathogens, and shellfish have been suggested as one of their reservoirs. However, only a few studies have investigated the presence of Arcobacter in this kind of food. This study assesses the prevalence and diversity of Arcobacter spp. in shellfish by multiplex PCR (m-PCR) and culturing methods (under different atmospheric conditions) and evaluates the possible influence of environmental parameters (temperature, salinity, and harvesting bay). Arcobacter was detected by m-PCR and/or culturing in 61 (29.9%) of 204 shellfish samples. Of the positive samples by culturing, 41.1% were obtained under only aerobic incubation conditions, while 23.2% were obtained under only microaerobic conditions. Of 476 investigated isolates, 118 belonged to different enterobacterial repetitive intergenic consensus (ERIC)-PCR genotypes (strains) and to 11 different species. This study shows the highest diversity of Arcobacter species ever observed in samples from any origin. The most prevalent species was Arcobacter butzleri (60.2%), followed by Arcobacter molluscorum (21.2%). The prevalence of Arcobacter was significantly higher during the summer than in other seasons, being associated with an increase in water temperature. Results confirm that shellfish are a reservoir for a remarkable diversity of Arcobacter spp.

  14. Ecological and evolutionary conditions for fruit abortion to regulate pollinating seed-eaters and increase plant production

    Holland, J. Nathaniel; DeAngelis, Donald L.


    Coevolved mutualisms, such as those between senita cacti, yuccas, and their respective obligate pollinators, benefit both species involved in the interaction. However, in these pollination mutualisms the pollinator's larvae impose a cost on plants through consumption of developing seeds and fruit. The effects of pollinators on benefits and costs are expected to vary with the abundance of pollinators, because large population sizes result in more eggs and larval seed-eaters. Here, we develop the hypothesis that fruit abortion, which is common in yucca, senita, and plants in general, could in some cases have the function of limiting pollinator abundance and, thereby, increasing fruit production. Using a general steady-state model of fruit production and pollinator dynamics, we demonstrate that plants involved in pollinating seed-eater mutualisms can increase their fecundity by randomly aborting fruit. We show that the ecological conditions under which fruit abortion can improve plants fecundity are not unusual. They are best met when the plant is long-lived, the population dynamics of the pollinator are much faster than those of the plant, the loss of one fruit via abortion kills a larva that would have the expectation of destroying more than one fruit through its future egg laying as an adult moth, and the effects of fruit abortion on pollinator abundance are spatially localized. We then use the approach of adaptive dynamics to find conditions under which a fruit abortion strategy based on regulating the pollinator population could feasibly evolve in this type of plant–pollinator interaction.

  15. Mechano-electric Effect of Hardened Cement Paste During Quasi-static Loading


    Mechano-electric effect of cement paste was investigated in this paper. As compressive stress was applied on the specimen, an electrical current was observed. The intensity of the electrical current increased with stress increasing, and decreased with stress decreasing. Different measurement methods were also discussed in this paper. This phenomenon was related to the electrokinetic phenomenon of solid/liquid interface in cement paste. The study on mechano-electric effect of hardened cement paste provides a new method for making smart concrete structures.

  16. Cat odor causes long-lasting contextual fear conditioning and increased pituitary-adrenal activation, without modifying anxiety.

    Muñoz-Abellán, Cristina; Daviu, Nuria; Rabasa, Cristina; Nadal, Roser; Armario, Antonio


    A single exposure to a cat or cat odors has been reported by some groups to induce contextual and auditory fear conditioning and long-lasting changes in anxiety-like behaviour, but there is no evidence for parallel changes in biological stress markers. In the present study we demonstrated in male rats that exposure to a novel environment containing a cloth impregnated with cat fur odor resulted in avoidance of the odor, lower levels of activity and higher pituitary-adrenal (PA) response as compared to those exposed to the novel environment containing a clean cloth, suggesting increased levels of stress in the former animals. When re-exposed 9 days later to the same environment with a clean cloth, previously cat fur exposed rats again showed avoidance of the cloth area and lower levels of activity, suggesting development of contextual fear conditioning, which again was associated with a higher PA activation. In contrast, unaltered both anxiety-like behaviour and PA responsiveness to an elevated plus-maze were found 7 days after cat odor exposure. It is concluded that: (i) PA activation is able to reflect both the stressful properties of cat fur odor and odor-induced contextual fear conditioning; (ii) development of cat odor-induced contextual fear conditioning is independent of the induction of long-lasting changes in anxiety-like behaviour; and (iii) greater PA activation during exposure to the odor context is not explained by non-specific sensitization of the PA axis caused by previous exposure to cat fur odor.

  17. Inoculation of Schizolobium parahyba with mycorrhizal fungi and plant growth-promoting rhizobacteria increases wood yield under field conditions

    Martha Viviana Torres Cely


    Full Text Available Schizolobium parahyba var. amazonicum (Huber ex Ducke occurs naturally in the Brazilian Amazon. Currently, it is being planted extensively because of its fast growth and excellent use in forestry. Consequently, there is great interest in new strategies to increase wood production. The interaction between soil microorganisms and plants, specifically in the roots, provides essential nutrients for plant growth. These interactions can have growth-promoting effects. In this way, this study assessed the effect of the inoculation with arbuscular mycorrhizal fungi (AMF and plant growth-promoting rhizobacteria (PGPR on growth of S. parahyba var. amazonicum under field conditions. We used two native species of arbuscular mycorrhizal fungi, Claroideoglomus etunicatum (Ce and Acaulospora sp. (Ac; two native strains of Rhizobium sp. (Rh1 and Rh2; and a non-native strain of Burkholderia sp. Different combinations of microorganisms were supplemented with chemical fertilizers (doses D1 and D2 in two planting methods, seed sowing and seedling planting. In seed sowing, the results showed that treatments with Ce/Rh1/Fertilizer D2 and Ac/No PGPR/Fertilizer D2 increased wood yield. In seedling planting, two combinations (Ac/Rh2/Fertilizer D1 and Ac/Rh1/Fertilizer D1 were more effective in increasing seedling growth. In these experiments, inoculation with AMF and PGPR increased wood yield by about 20% compared to the application of fertilizer alone.

  18. Inoculation of Schizolobium parahyba with Mycorrhizal Fungi and Plant Growth-Promoting Rhizobacteria Increases Wood Yield under Field Conditions

    Cely, Martha V. T.; Siviero, Marco A.; Emiliano, Janaina; Spago, Flávia R.; Freitas, Vanessa F.; Barazetti, André R.; Goya, Erika T.; Lamberti, Gustavo de Souza; dos Santos, Igor M. O.; De Oliveira, Admilton G.; Andrade, Galdino


    Schizolobium parahyba var. amazonicum (Huber ex Ducke) occurs naturally in the Brazilian Amazon. Currently, it is being planted extensively because of its fast growth and excellent use in forestry. Consequently, there is great interest in new strategies to increase wood production. The interaction between soil microorganisms and plants, specifically in the roots, provides essential nutrients for plant growth. These interactions can have growth-promoting effects. In this way, this study assessed the effect of the inoculation with arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) on growth of S. parahyba var. amazonicum under field conditions. We used two native species of arbuscular mycorrhizal fungi, Claroideoglomus etunicatum (Ce), and Acaulospora sp. (Ac); two native strains of Rhizobium sp. (Rh1 and Rh2); and a non-native strain of Burkholderia sp. Different combinations of microorganisms were supplemented with chemical fertilizers (doses D1 and D2) in two planting methods, seed sowing and seedling planting. In seed sowing, the results showed that treatments with Ce/Rh1/Fertilizer D2 and Ac/No PGPR/Fertilizer D2 increased wood yield. In seedling planting, two combinations (Ac/Rh2/Fertilizer D1 and Ac/Rh1/Fertilizer D1) were more effective in increasing seedling growth. In these experiments, inoculation with AMF and PGPR increased wood yield by about 20% compared to the application of fertilizer alone. PMID:27920781

  19. Research into Grinding Hardening of Microalloyed Non-quenched and Tempered Steel

    HAN Zheng-tong; ZHANG Ning-ju; GAO Ding; YANG Gang


    Grinding hardening is a new technology of hardening steel piece surfaces with grinding heat generated in the grinding process instead of with a high or medium frequency induction heating method, which can effectively integrate grinding and surface hardening. Experimental studies were carried out on grinding hardening of non-quenched and tempered steel. Through grinding experiments with variable depths of cut and feeding rate, the variation in the depth of the hardening layer was studied and the microstructure of the hardening zone of the test pieces was subsequently analyzed. In the end, the hardening effect of non-quenched and tempered steel was compared with that of 40Cr steel, which revealed the superiority of non-quenched and tempered steel in grinding hardening technology.

  20. Corroding and Protecting of Surface Residual Stress With the Surface Hardening of Steel

    ZOU Qing-hua


    The states of the stress with the surface hardening are analyzed, the related experiential formula of the stress -temperature and stress-depth hardened curves are set up, the protecting measures against hydrogen stress corrosion are discussed.

  1. AgRP Neurons Can Increase Food Intake during Conditions of Appetite Suppression and Inhibit Anorexigenic Parabrachial Neurons.

    Essner, Rachel A; Smith, Alison G; Jamnik, Adam A; Ryba, Anna R; Trutner, Zoe D; Carter, Matthew E


    To maintain energy homeostasis, orexigenic (appetite-inducing) and anorexigenic (appetite suppressing) brain systems functionally interact to regulate food intake. Within the hypothalamus, neurons that express agouti-related protein (AgRP) sense orexigenic factors and orchestrate an increase in food-seeking behavior. In contrast, calcitonin gene-related peptide (CGRP)-expressing neurons in the parabrachial nucleus (PBN) suppress feeding. PBN CGRP neurons become active in response to anorexigenic hormones released following a meal, including amylin, secreted by the pancreas, and cholecystokinin (CCK), secreted by the small intestine. Additionally, exogenous compounds, such as lithium chloride (LiCl), a salt that creates gastric discomfort, and lipopolysaccharide (LPS), a bacterial cell wall component that induces inflammation, exert appetite-suppressing effects and activate PBN CGRP neurons. The effects of increasing the homeostatic drive to eat on feeding behavior during appetite suppressing conditions are unknown. Here, we show in mice that food deprivation or optogenetic activation of AgRP neurons induces feeding to overcome the appetite suppressing effects of amylin, CCK, and LiCl, but not LPS. AgRP neuron photostimulation can also increase feeding during chemogenetic-mediated stimulation of PBN CGRP neurons. AgRP neuron stimulation reduces Fos expression in PBN CGRP neurons across all conditions. Finally, stimulation of projections from AgRP neurons to the PBN increases feeding following administration of amylin, CCK, and LiCl, but not LPS. These results demonstrate that AgRP neurons are sufficient to increase feeding during noninflammatory-based appetite suppression and to decrease activity in anorexigenic PBN CGRP neurons, thereby increasing food intake during homeostatic need.SIGNIFICANCE STATEMENT The motivation to eat depends on the relative balance of activity in distinct brain regions that induce or suppress appetite. An abnormal amount of activity in

  2. [Influence of cryogenic treatment and age-hardening heat treatment on the microhardness of palladium-silver dental alloys].

    Zhao, Yao; Tong, Xu; Liu, Jiajun; Hao, Zhichao; Meng, Yukun


    The purpose of this study was to investigate the influence of cryogenic treatment and age-hardening heat treatment on the micro-Vicker's hardness of palladium-silver dental alloys. A low-gold content dental casting alloy composed of Ag-Pd-Cu-Au was prepared for this study. Experimental specimens according to standard requirements were prepared following a standard dental laboratory casting procedure, cast specimens were heated to 900 degrees C and quenched in ice water. The specimens were then divided into 4 groups. They were subsequently subjected to different treatments, including age-hardening heat treatment, cryogenic treatment, heat treatment combined with cryogenic treatment. The non-treated group was used as control. The micro-Vicker's hardness value was examined. The significance of correlation was analyzed. The micro-Vicker's hardness of specimens after age-hardening heat treatment, cryogenic treatment, heat treatment combined with cryogenic treatment increased by 129%, 13% and 141%, respectively, compared with that of the non-treated control group. Conclusion Age-hardening heat treatment and cryogenic treatment were effective in elevating the hardness of Ag-Pd-Cu-Au alloy.

  3. Unraveling the Initial Microstructure Effects on Mechanical Properties and Work-Hardening Capacity of Dual-Phase Steel

    Mirzadeh, Hamed; Alibeyki, Mohammad; Najafi, Mostafa


    Ferritic-martensitic, dual-phase (DP) microstructures with different size, morphology, and distribution of martensite were produced by altering the initial microstructures using heat treatment and thermomechanical processing routes. It was revealed that the strength, ductility, and work-hardening rate of DP steels strongly depend on the volume fraction and the morphology of the martensite phase. In this regard, the fine-grained DP microstructure showed a high work-hardening ability toward an excellent combination of strength and ductility. Such a microstructure can be readily obtained by intercritical annealing of an ultrafine grained (UFG) microstructure, where the latter can be produced by cold-rolling followed by tempering of a martensite starting microstructure. Conclusively, the enhancement of mechanical properties of DP steels through microstructural refinement was found to be more beneficial compared with increasing the volume fraction of martensite. Finally, it was also demonstrated that the work-hardening rate analysis based on the instantaneous (incremental) work-hardening exponents might be an advantageous approach for characterizing DP steels along with the conventional approaches.

  4. Strain hardening and jump-like deformation of ultrafine polycrystalline Al-Li solid solutions at 0.5 K

    Isaev, N. V.; Shumilin, S. E.; Zabrodin, P. A.; Geidarov, V. G.; Grigorova, T. V.; Fomenko, V. S.; Braude, I. S.; Pustovalov, V. V.


    This is a study of the effect of microstructure created by severe plastic deformation (SPD) and annealing on strain hardening and jump-like deformation in Al-Li alloys. It is shown that under tension at 0.5 K, SPD processed polycrystals retain a significant strain hardening rate and have high strength and ductility. SPD also simulates unstable (jump-like) flow of the polycrystals owing to dislocation dynamics that shows up as stress jumps in the tension curve. The average amplitude of the jumps increases with strain, while the dislocation amplitude distribution corresponds to collective motion of dislocation avalanches with a distinctive scale. Jump-like deformation is partially suppressed by high-temperature annealing, while the distribution of the jump amplitudes is described by a power law. The relationship established between the coefficient of strain hardening and the average stress jump amplitude suggests a common dislocation dynamic for strain hardening and jump-like deformation at low temperatures. The observed features of low-temperature plastic deformation are treated as a consequence of changes in the grain sizes and density of dislocations owing to SPD and annealing.

  5. Conditioning of Parsley (Petroselinum crispum L.) Suspension Cells Increases Elicitor-Induced Incorporation of Cell Wall Phenolics.

    Kauss, H.; Franke, R.; Krause, K.; Conrath, U.; Jeblick, W.; Grimmig, B.; Matern, U.


    The elicitor-induced incorporation of phenylpropanoid derivatives into the cell wall and the secretion of soluble coumarin derivatives (phytoalexins) by parsley (Petroselinum crispum L.) suspension cultures can be potentiated by pretreatment of the cultures with 2,6-dichloroisonicotinic acid or derivatives of salicylic acid. To investigate this phenomenon further, the cell walls and an extracellular soluble polymer were isolated from control cells or cells treated with an elicitor from Phytophthora megasperma f. sp. glycinea. After alkaline hydrolysis, both fractions from elicited cells showed a greatly increased content of 4-coumaric, ferulic, and 4-hydroxybenzoic acid, as well as 4-hydroxybenzaldehyde and vanillin. Two minor peaks were identified as tyrosol and methoxytyrosol. The pretreatment effect is most pronounced at a low elicitor concentration. Its specificity was elaborated for coumarin secretion. When the parsley suspension cultures were preincubated for 1 d with 2,6-dichloroisonicotinic, 4- or 5-chlorosalicylic, or 3,5- dichlorosalicylic acid, the cells exhibited a greatly increased elicitor response. Pretreatment with isonicotinic, salicylic, acetylsalicylic, or 2,6-dihydroxybenzoic acid was less efficient in enhancing the response, and some other isomers were inactive. This increase in elicitor response was also observed for the above-mentioned monomeric phenolics, which were liberated from cell walls upon alkaline hydrolysis and for "lignin-like" cell wall polymers determined by the thioglycolic acid method. It was shown for 5-chlorosalicylic acid that conditioning most likely improves the signal transduction leading to the activation of genes encoding phenylalanine ammonia lyase and 4-coumarate: coenzyme A ligase. The conditioning thus sensitizes the parsley suspension cells to respond to lower elicitor concentrations. If a similar mechanism were to apply to whole plants treated with 2,6-dichloroisonicotinic acid, a known inducer of systemic

  6. Radiation Hardened Electronics Destined For Severe Nuclear Reactor Environments

    Holbert, Keith E. [Arizona State Univ., Tempe, AZ (United States); Clark, Lawrence T. [Arizona State Univ., Tempe, AZ (United States)


    Post nuclear accident conditions represent a harsh environment for electronics. The full station blackout experience at Fukushima shows the necessity for emergency sensing capabilities in a radiation-enhanced environment. This NEET (Nuclear Energy Enabling Technologies) research project developed radiation hardened by design (RHBD) electronics using commercially available technology that employs commercial off-the-shelf (COTS) devices and present generation circuit fabrication techniques to improve the total ionizing dose (TID) hardness of electronics. Such technology not only has applicability to severe accident conditions but also to facilities throughout the nuclear fuel cycle in which radiation tolerance is required. For example, with TID tolerance to megarads of dose, electronics could be deployed for long-term monitoring, inspection and decontamination missions. The present work has taken a two-pronged approach, specifically, development of both board and application-specific integrated circuit (ASIC) level RHBD techniques. The former path has focused on TID testing of representative microcontroller ICs with embedded flash (eFlash) memory, as well as standalone flash devices that utilize the same fabrication technologies. The standalone flash devices are less complicated, allowing better understanding of the TID response of the crucial circuits. Our TID experiments utilize biased components that are in-situ tested, and in full operation during irradiation. A potential pitfall in the qualification of memory circuits is the lack of rigorous testing of the possible memory states. For this reason, we employ test patterns that include all ones, all zeros, a checkerboard of zeros and ones, an inverse checkerboard, and random data. With experimental evidence of improved radiation response for unbiased versus biased conditions, a demonstration-level board using the COTS devices was constructed. Through a combination of redundancy and power gating, the demonstration

  7. Analysis of Laser Surface Hardened Layers of Automobile Engine Cylinder Liner

    LIU Xiu-bo; YU Gang; GUO Jian; SHANG Quan-yi; ZHANG Zhen-guo; GU Yi-jie


    Gray cast iron that is used for automobile engine cylinder liners was laser surface hardened using Nd∶YAG quasi-continuous and CO2 continuous wave laser, respectively. The macromorphology and microstructure of the laser surface hardened layers were investigated using an optical microscope. Geometric dimensions including depth and width and microhardness distribution of the hardened layers were also examined in order to evaluate the quality of the hardened layers.

  8. Hardening digital systems with distributed functionality: robust networks

    Vaskova, Anna; Portela-Garcia, Marta; Garcia-Valderas, Mario; López-Ongil, Celia; Portilla, Jorge; Valverde, Juan; de la Torre, Eduardo; Riesgo, Teresa


    Collaborative hardening and hardware redundancy are nowadays the most interesting solutions in terms of fault tolerance achieved and low extra cost imposed to the project budget. Thanks to the powerful and cheap digital devices that are available in the market, extra processing capabilities can be used for redundant tasks, not only in early data processing (sensed data) but also in routing and interfacing1

  9. Hardening by twin boundary during nanoindentation in nanocrystals.

    Qu, Shaoxing; Zhou, Haofei


    The atomistic deformation processes of nanocrystals embedded with nanoscale twin boundaries during nanoindentation are studied by molecular dynamics simulations. Load-displacement curves are obtained and the hardening mechanisms associated with the nanoscale twin boundaries are revealed. Johnson's theoretical indentation model is adopted to estimate the elastic stage of the nanoindentation. In addition, twin boundary-mediated dislocation nucleation is observed and analyzed.

  10. Preparation of Dispersion-Hardened Copper by Internal Oxidation

    Brøndsted, Povl; Sørensen, Ole Toft


    Internal oxidation experiments in CO2/CO atmospheres on Cu-Al alloys for preparation of dispersion-hardened Cu are described. The oxygen pressures of the atmospheres used in the experiments were controlled with a solid electrolyte oxygen cell based on ZrO2 (CaO). The particle size distributions...

  11. Coefficient of work-hardening in stage-IV

    Nabarro, FRN


    Full Text Available The theory of work hardening in stage IV depends on the relation between the relative misorientation Psi of neighbouring subgrains and the plastic strain gamma (Psi = B gamma exp). The value of the constant B is suggested to be better related...

  12. Decorative application of strain-hardening cementitious composites

    Ibrovic, V.; Lukovic, M.; Schlangen, E.


    Strain hardening cementitious composites (SHCC) have been used in variety of structural applications. Apart from this, they are also suitable for non-structural applications. In this work, the application of SHCC for producing cover plates for light switches and power sockets is presented. For desig

  13. Case Depth Measurement of Induction Hardening Using Image Processing

    Kitti Pongsathaporn; Pramuk Jenkittiyon; Siriporn Daopiset; Somnuk Watanasriyakul


    Case depth measurement of the induction hardened steel parts is necessary for quality control. Vickers microhardness test is the most industrially accepted method to identify the case depth. But this method is a time consuming one and it requires expensive equipment. The aim of this study is to develop a different method to determine the case depth using image processing. The surface hardened steel samples were cross cut, ground and etched with Nital. The etched macrosectioned specimens were scanned by a scanner. The scanned images were evaluated by the developed software. The principle of the software is to identify the gray level difference. The effective case depths of the surface hardened specimens obtained by Vickers microhardness test and the developed method were compared. It was found that the deviation of the developed method was ±0.12 mm at the case depth range of 0.6 - 2.0 mm and ±0.14 mm at the case depth range of 2.1 - 4.3 mm. The measuring time was only 20% of Vickers microhardness test. The deviation range is much lower than the tolerance case depth specification for induction hardening in general.

  14. Decorative application of strain-hardening cementitious composites

    Ibrovic, V.; Lukovic, M.; Schlangen, E.


    Strain hardening cementitious composites (SHCC) have been used in variety of structural applications. Apart from this, they are also suitable for non-structural applications. In this work, the application of SHCC for producing cover plates for light switches and power sockets is presented. For

  15. Application of Artificial Neural Network to Predicting Hardenability of Gear Steel

    GAO Xiu-hua; QI Ke-min; DENG Tian-yong; QIU Chun-lin; ZHOU Ping; DU Xian-bin


    The prediction of the hardenability and chemical composition of gear steel was studied using artificial neural networks. A software was used to quantitatively forecast the hardenability by its chemical composition or the chemical composition by its hardenability. The prediction result is more precise than that obtained from the traditional method based on the simple mathematical regression model.

  16. The prediction of differential hardening behaviour of steels by multi-scale crystal plasticity modelling

    Eyckens, P.; Mulder, J.; Gawad, J.; Vegter, H.; Roose, D.; Boogaard, van den A.H.; Van Bael, A.; Van Houtte, P.


    An essential aspect of materials modelling in the field of metal plasticity is hardening. The classical assumption of isotropic hardening in metal plasticity models is often too simplified to describe actual material behaviour. This paper focuses on the non-isotropic hardening termed differential ha

  17. Study of the mechanisms involved in the laser superficial hardening process of metallic alloys; Estudo dos mecanismos envolvidos no processo de endurecimento superficial a laser de ligas metalicas

    Silva, Edmara Marques Rodrigues da


    The laser superficial hardening process of a ferrous alloy (gray cast iron) and of an aluminum-silicon alloy was investigated in this work. These metallic alloys are used in the automobile industry for manufacturing cylinders and pistons, respectively. By application of individual pulses and single tracks, the involved mechanisms during the processing were studied. Variables such as energy density, power density, temporal width, beam diameter on the sample surface, atmosphere of the processing region, overlapping and scanning velocity. The hardened surface was characterized by optical and scanning electronic microscopy, dispersive energy microanalysis, X-ray mapping, X-ray diffraction, and measurements of roughness and Vickers microhardness. Depending on the processing parameters, it is possible to obtain different microstructures. The affected area of gray cast iron, can be hardened by remelting or transformation hardening (total or partial) if the reached temperature is higher or not that of melting temperature. Laser treatment originated new structures such as retained austenite, martensite and, occasionally, eutectic of cellular dendritic structure. Aluminum-silicon alloy does not have phase transformation in solid state, it can be hardened only by remelting. The increase of hardness is a function of the precipitation hardening process, which makes the silicon particles smaller and more disperse in the matrix. Maximal values of microhardness (700-1000 HV) were reached with the laser treatment in gray cast iron samples. The initial microhardness is of 242 HV. For aluminum-silicon alloy, the laser remelting increases the initial microhardness of 128 HV to the range of 160-320 HV. The found results give a new perspective for using the CLA/IPEN's laser in the heat treatment area. Besides providing a higher absorptivity to the materials, compared with the CO{sub 2} laser, and optical fiber access, the superficial hardening with Nd:YAG laser, depending on the

  18. Pavlovian conditioning of corticotropin-releasing factor-induced increase of blood pressure and corticosterone secretion in the rat.

    Kreutz, M; Hellhammer, D; Murison, R; Vetter, H; Krause, U; Lehnert, H


    Corticotropin-releasing factor (CRF) is clearly involved in the central regulation of the pituitary-adrenal axis and, moreover, of autonomic nervous system functions. Enhanced sympathetic activity with subsequent increases in blood pressure and heart rate and attenuation of the baroreceptor reflex results from the intracerebroventricular (i.c.v.) administration of CRF. Additionally, the peptide has a variety of potent effects on behavioural responses in animals similar to those observed after an experimentally evoked stress. It was therefore of obvious interest to examine whether CRF is a possible mediator of the learning processes associated with physiological stress reaction patterns. This report clearly demonstrates a classical conditioning of the endocrine (i.e. corticosterone secretion) and haemodynamic (i.e. blood pressure) sequelae following central CRF application and thus indicates that this mechanism is of physiological significance for learned stress responses.

  19. Evaluating the impact of demand-side management on water resources under changing climatic conditions and increasing population.

    Dawadi, Srijana; Ahmad, Sajjad


    This study investigated the effect of increasing population and changing climatic conditions on the water resources of a semi-arid region, the Las Vegas Valley (LVV) in southern Nevada. A system dynamics model was developed for the LVV from 1989 to 2035. The impact of climate change on water demand and the water supply from the Colorado River was modeled, using projections from 16 global climate models for 3 emission scenarios. Variability in water demand and supply under different scenarios of population growth and demand management, including water conservation and water pricing, was evaluated. With the population growth that was projected, if no further demand management policies were implemented, the LVV would not be able to meet the water demand in the near future. However, by combining water conservation and pricing policies, the available supply could last well into the future. The reduction in water demand in 2035 was predicted to be 327 million cubic meters (MCM) for 'status quo' population growth, or 30.6%; 408 MCM for 50% of the projected growth, or 38%; and 511 MCM for no population growth, or 47.8%. Water supply reliability decreased significantly with changing climatic conditions. Therefore, major challenges to water sustainability in the LVV would be due to rapid population growth as well as to climate variability. However, with the combination of reduced population growth rate and water conservation policies, the Colorado River supply could meet the future demand of the LVV most of the time.

  20. The cyanobacterial hepatotoxin microcystin binds to proteins and increases the fitness of microcystis under oxidative stress conditions.

    Zilliges, Yvonne; Kehr, Jan-Christoph; Meissner, Sven; Ishida, Keishi; Mikkat, Stefan; Hagemann, Martin; Kaplan, Aaron; Börner, Thomas; Dittmann, Elke


    Microcystins are cyanobacterial toxins that represent a serious threat to drinking water and recreational lakes worldwide. Here, we show that microcystin fulfils an important function within cells of its natural producer Microcystis. The microcystin deficient mutant ΔmcyB showed significant changes in the accumulation of proteins, including several enzymes of the Calvin cycle, phycobiliproteins and two NADPH-dependent reductases. We have discovered that microcystin binds to a number of these proteins in vivo and that the binding is strongly enhanced under high light and oxidative stress conditions. The nature of this binding was studied using extracts of a microcystin-deficient mutant in vitro. The data obtained provided clear evidence for a covalent interaction of the toxin with cysteine residues of proteins. A detailed investigation of one of the binding partners, the large subunit of RubisCO showed a lower susceptibility to proteases in the presence of microcystin in the wild type. Finally, the mutant defective in microcystin production exhibited a clearly increased sensitivity under high light conditions and after hydrogen peroxide treatment. Taken together, our data suggest a protein-modulating role for microcystin within the producing cell, which represents a new addition to the catalogue of functions that have been discussed for microbial secondary metabolites.

  1. Reconstructing pre-impact baseline conditions using benthic foraminifera in an area of increasing petroleum exploration activities

    Dijkstra, Noortje; Junttila, Juho; Aagaard-Sørensen, Steffen


    While macrofauna is traditionally used to bio-monitor to state of the ecosystem, benthic foraminifera have large potential for bio-monitoring as well. As their tests stay preserved in the sedimentary archive it is possible to reconstruct pre-impacted conditions, by studying foraminiferal assemblages in sediment cores. The use of foraminiferal faunas as bio-monitoring tools is complicated by the natural variability. Therefore, detailed site specific studies are needed, to understand the range of natural variability of the area of interest. This study characterizes the natural variability in the Bjørnøyrenna-Ingøydjupet area in the Southern Barents Sea. The Southern Barents Sea is a relatively un-impacted and uncontaminated area, however petroleum industry related activities are expected to increase in the near future. This makes the area a valuable natural laboratory to establish pre-impacted baselines for future seabed monitoring programs. Benthic foraminiferal assemblages were examined at high resolution in sediment cores and compared to sediment properties and metal concentrations. Species associated to temperate water masses dominate in the southern part of the study area, while species associated to cooler water masses increase in abundance towards the north into Bjørnøyrenna. Additionally, the foraminiferal assemblages might reflect climatic oscillations on both millennial and decadal time scales. Patterns in the calcareous foraminiferal assemblages suggest an enhanced food supply as a result of increased Atlantic Water inflow through the region during the last 150 years. Sediment TOC content has been linked with variable inflow of Atlantic Water. A strong positive correlation was observed between TOC content with metal content in the cores. It is therefore essential to consider the role of natural variability of oceanographic conditions when using benthic foraminiferal assemblages to monitor for potential anthropogenic impacts on the environment. This

  2. Effects of cold-hardening on compatible solutes and antioxidant enzyme activities related to freezing tolerance in Ammopiptanthus mongolicus seedlings

    WANG Wei-juan; CHEN Yu-zhen; LIU Mei-qin; LU Cun-fu


    Cold acclimation is associated with many metabolic changes that lead to an increase of freezing tolerance. In order to investigate the biochemical process of cold acclimation in Ammopiptanthus mongolicus, seedlings were acclimated at 2℃ under 16-h photoperiod (150 μmol·m-2·s-1 photosynthetically active radiation) for 14 d. Freezing tolerance in seedlings increased after 14 d of cold-hardening. Contents of protein, proline and solute carbohydrate in cotyledon increased after cold acclimation. Patterns of isozymes of superoxide dismutase (SOD), peroxidase, catalase and polyphenol oxidase (PPO) were investigated. The activities of SOD, peroxidase and PPO in cold acclimated plants were increased during cold-hardening. We deduced that compatible solutes and antioxidant enzymes play important roles in development of freezing tolerance during cold acclimation in this evergreen woody plant.

  3. Co speciation in hardened cement paste: a macro- and micro-spectroscopic investigation.

    Vespa, M; Dähn, R; Grolimund, D; Wieland, E; Scheidegger, A M


    Cement-based materials play an important role in multi-barrier concepts developed worldwide for the safe disposal of hazardous and radioactive wastes. Cement is used to condition and stabilize the waste materials and to construct the engineered barrier systems (container, backfill and liner materials) of repositories for radioactive waste. In this study, Co uptake by hardened cement paste (HCP) has been investigated with the aim of improving our understanding of the immobilization process of heavy metals in cement on the molecular level. X-ray-absorption spectroscopy (XAS) on powder material (bulk-XAS) was used to determine the local environment of Co in cement systems. Bulk-XAS investigations were complemented with micro-beam investigations to probe the inherent microscale heterogeneity of cement by using micro-X-ray-fluorescence (micro-XRF) and micro-XAS. Micro-XRF was used to gain information on the spatial heterogeneity of the Co distribution, whereas micro-XAS was employed to determine the speciation of Co on the microscale. The Co-doped HCP samples hydrated for time-scales from 1 hour up to 1 year were prepared under normal atmosphere, to simulate similar conditions as for waste packages. To investigate the role of oxygen, further samples were prepared in the absence of oxygen. The study showed that, for the samples prepared in air, Co(II) is oxidized to Co(III) after 1 hour of hydration time. Moreover, the relative amount of Co(III) increases with increasing hydration time. The study further revealed that Co(II) is predominately present as a Co-hydroxide-like phase and/or Co-phyllosilicates, whereas Co(III) tends to be incorporated into a CoOOH-like phase and/or Co-phyllomanganates. In contrast to samples prepared in air, XAS experiments with samples prepared in the absence of oxygen revealed solely the presence of Co(II). This finding indicates that oxygen plays an important role for Co oxidation in cement. Furthermore, the study suggests that Co


    Ahmet Çetin CAN


    Full Text Available Machine parts are surface hardened to increase fatigue strength and wear resistance. Carburization is the most common surface hardening process in practice. In order to have optimum properties, a machine part must have certain hardness depth. To obtain required hardness depth, the parts must be kept in a carburizing medium at certain temperature for certain time. As the time and temperature is increased hardness depth increases. In practice, carburization temperature is about 930 °C. Machine parts are kept at this temperature for required time depending on required hardness depth. The increase of temperature reduces treatment time, considerably. But, heat treaters do not tend to use high temperatures due to the concern of distortion of parts, and deterioration of mechanical properties. In this study, the increase of temperature for reducing carburization time in salt bath, and consequently change of mechanical properties have been investigated using DIN C20 case carburization steel. As a result of experiments, it was found that mechanical properties were not effected negatively.

  5. Simultaneous Inhibition of Linolenic Acid Synthesis in Winter Wheat Roots and Frost Hardening by BASF 13-338, a Derivative of Pyridazinone.

    Willemot, C


    Treatment of 12-day-old winter wheat (Triticum aestivum) plants with BASF 13-338 {4-chloro-5 (dimethylamino)-2-phenyl-3(2H)-pyridazinone} 36 hours before frost hardening simultaneously and completely inhibits accumulation of linolenic acid in the roots during the hardening period and the acquisition of frost resistance. Increased unsaturation of fatty acids is therefore probably an important part of the mechanism of cold adaptation in winter wheat.BASF 13-338 also prevents the increase in per cent dry weight in roots and shoots during hardening and causes a decrease in root lipid phosphorus and total fatty acids.The concurrent increase in linoleic acid and decrease in linolenic acid in the treated plants, while the level of the other fatty acids is but little affected, suggest that BASF 13-338 specifically inhibits linoleic acid desaturase.

  6. Increasing the antioxidant activity, total phenolic and flavonoid contents by optimizing the germination conditions of amaranth seeds.

    Perales-Sánchez, Janitzio X K; Reyes-Moreno, Cuauhtémoc; Gómez-Favela, Mario A; Milán-Carrillo, Jorge; Cuevas-Rodríguez, Edith O; Valdez-Ortiz, Angel; Gutiérrez-Dorado, Roberto


    The aim of this study was to optimize the germination conditions of amaranth seeds that would maximize the antioxidant activity (AoxA), total phenolic (TPC), and flavonoid (TFC) contents. To optimize the germination bioprocess, response surface methodology was applied over three response variables (AoxA, TPC, TFC). A central composite rotable experimental design with two factors [germination temperature (GT), 20-45 ºC; germination time (Gt), 14-120 h] in five levels was used; 13 treatments were generated. The amaranth seeds were soaked in distilled water (25 °C/6 h) before germination. The sprouts from each treatment were dried (50 °C/8 h), cooled, and ground to obtain germinated amaranth flours (GAF). The best combination of germination bioprocess variables for producing optimized GAF with the highest AoxA [21.56 mmol trolox equivalent (TE)/100 g sample, dw], TPC [247.63 mg gallic acid equivalent (GAE)/100 g sample, dw], and TFC [81.39 mg catechin equivalent (CAE)/100 g sample, dw] was GT = 30 ºC/Gt = 78 h. The germination bioprocess increased AoxA, TPC, and TFC in 300-470, 829, and 213%, respectively. The germination is an effective strategy to increase the TPC and TFC of amaranth seeds for enhancing functionality with improved antioxidant activity.

  7. Design of an age hardening Mg-Li alloy and its aging behavior

    Hao Zhong; Peiying Liu; Tietao Zhou; Huanxi Li


    An effort was made to design an age hardening Mg-Li alloy based on the phase diagrams calculated by means of "THERMO-CALC"-a thermodynamic software. Experiments were carried out to verify the calculated results by melting the alloy and examining its structure and aging behavior. The results show that the alloy possesses a structure constituent as expected, besides,the alloy has apparent aging behavior and over aging happens even at lower temperature. Metastable (Mg, Li, Al, Zn) phase has been identified when the hardness reaches the aging peak. With the increase of the aging time, (Mg, Li, Al, Zn) phase transforms to stable α phase and over aging happens.

  8. Increased PSA expression on prostate cancer exosomes in in vitro condition and in cancer patients.

    Logozzi, Mariantonia; Angelini, Daniela F; Iessi, Elisabetta; Mizzoni, Davide; Di Raimo, Rossella; Federici, Cristina; Lugini, Luana; Borsellino, Giovanna; Gentilucci, Alessandro; Pierella, Federico; Marzio, Vittorio; Sciarra, Alessandro; Battistini, Luca; Fais, Stefano


    Prostate specific antigen (PSA) test is the most common, clinically validated test for the diagnosis of prostate cancer (PCa). While neoplastic lesions of the prostate may cause aberrant levels of PSA in the blood, the quantitation of free or complexed PSA poorly discriminates cancer patients from those developing benign lesions, often leading to invasive and unnecessary surgical procedures. Microenvironmental acidity increases exosome release by cancer cells. In this study we evaluated whether acidity, a critical phenotype of malignancy, could influence exosome release and increase the PSA expression in nanovesicles released by PCa cells. To this aim, we exploited Nanoparticle Tracking Analysis (NTA), an immunocapture-based ELISA, and nanoscale flow-cytometry. The results show that microenvironmental acidity induces an increased release of nanovesicles expressing both PSA and the exosome marker CD81. In order to verify whether the changes induced by the local selective pressure of extracellular acidity may correspond to a clinical pathway we used the same approach to evaluate the levels of PSA-expressing exosomes in the plasma of PCa patients and controls, including subjects with benign prostatic hypertrophy (BPH). The results show that only PCa patients have high levels of nanovesicles expressing both CD81 and PSA. This study shows that tumor acidity exerts a selective pressure leading to the release of extracellular vesicles that express both PSA and exosome markers. A comparable scenario was shown in the plasma of prostate cancer patients as compared to both BPH and healthy controls. These results suggest that microenvironmental acidity may represent a key factor which determines qualitatively and quantitatively the release of extracellular vesicles by malignant tumors, including prostate cancer. This condition leads to the spill-over of nanovesicles into the peripheral blood of prostate cancer patients, where the levels of tumor biomarkers expressed by

  9. A conditional model for estimating the increase in suicides associated with the 2008-2010 economic recession in England.

    Saurina, Carme; Bragulat, Basili; Saez, Marc; López-Casasnovas, Guillem


    Although evidence of the effects of the economic crisis on suicides is quite low, a recent article shows that the increase in suicides in England between 2008 and 2010 could be associated with the rise in unemployment. Our study analysed whether this effect was the same for all regions of England, using a conditional model which explicitly allows estimation of regional time trends and the effects of unemployment on suicides at the regional level. Hierarchical mixed models were used to assess both, suicides attributable to the financial crisis and the association between unemployment and suicides. The number and the (age-standardised) rate of suicides, for men and women separately, were the dependent variables. We considered the nine English regions based on the NUTS 2 level. There was an (not statistically significant) increase in the number of suicides between 2008 and 2010. The variation in rates was not statistically significant in England as a whole but there were statistically significant increases and decreases in some regions. Statistically significant associations between unemployment and suicides were only found at regional level. For men, statistically significant unemployment rates were positively associated with age-standardised suicide rates in the South West (0.384), North West (0.260) and North East (0.136), and negatively associated in the East of England (-0.444), East Midlands (-0.236) and London (-0.168). The study provides evidence that, even with statistically significant associations, finding variability, but no clear pattern, between trends and associations and/or numbers and rates might in fact suggest relatively spurious relationships; this is a result of not controlling for confounders.


    Y. L. Bolshakov


    Full Text Available Purpose. The paper is aimed to determinate the main ways of increasing resource efficiency and exploitation of coal current collector surface inserts of speed electric rolling stock. Methodology. The research is based on the technique relies on the use of theory regulations of technical systems reliability, electromechanical processes, theory of statistics. Findings. The existing approaches to the production of current collector surface inserts in Europe and Ukraine were considered, a number of information sources was analyzed. The most effective ways of increasing current carrying capacity and wear resistance of current collector elements were determined. It has been established that the existing system for determining the quality of manufacturing of current collector elements have a number of drawbacks that make it difficult to control the input and makes diagnosing current collecting elements in operation impossible. On the basis of the facts, for the needs of the locomotive depot, we propose a new booth allowing avoiding the existing difficulties with diagnosing of current collector elements. During the study were established pervasive transgressions of technological standards of service pantographs. Originality. Based on the results of operational research carried out on the basis of the locomotive depot, obtained depending, based on which, it is proposed to introduce an operative diagnosing system of the current collector elements state during operation. In the course of a comparative analysis of existing and perspective development directions of current collector elements with high load current carrying capacity and durability, were definited constructive conditions for the optimal ratio is inserts. It was established that a significant proportion of failures occur due to imperfect maintenance system for which, on the basis of operational data, recommendations were developed. Practical value. Obtained results of the information sources

  11. Microstructural variation of hardened cement-fly ash pastes leached by soft water


    The microstructural variations of hardened cement-fly ash pastes leached by soft water were investigated by MIP, XRD, TG and SEM. The results show that the mass of hardened cement-fly ash paste reduces and its microstructure deteriorates partly after leaching of soft water. At the leaching duration of 180 days, the hardened paste containing fly ash deteriorated a little more serious than the plain cement paste, but the incorporation of fly ash in a proper ratio was helpful to defer the trend of deterioration of the hardened paste microstructure. The microstructural stability of hardened cement-fly ash paste wasn’t damaged severely during the 180 days leaching duration.

  12. Effect of hardening methods of moulding sands with water glass on structure of bonding bridges

    Stachowicz, M.; K. Granat; Nowak, D.


    Research on influence of hardening methods on structure of bonding bridges in moulding sands with sodium water glass is presented.Moulding sands with addition of 2.5 % of binder with molar module 2.0 were hardened with CO2 and dried in traditional way or hardenedwith microwaves. It was proved that the hardening method affects structure of bonding bridges, correlating with properties of the hardened moulding sands. It was found that strength of the moulding sands hardened with microwaves for 4...

  13. Thermophysical and Mechanical Properties of Hardened Cement Paste with Microencapsulated Phase Change Materials for Energy Storage

    Hongzhi Cui


    Full Text Available In this research, structural-functional integrated cement-based materials were prepared by employing cement paste and a microencapsulated phase change material (MPCM manufactured using urea-formaldehyde resin as the shell and paraffin as the core material. The encapsulation ratio of the MPCM could reach up to 91.21 wt%. Thermal energy storage cement pastes (TESCPs incorporated with different MPCM contents (5%, 10%, 15%, 20% and 25% by weight of cement were developed, and their thermal and mechanical properties were studied. The results showed that the total energy storage capacity of the hardened cement specimens with MPCM increased by up to 3.9-times compared with that of the control cement paste. The thermal conductivity at different temperature levels (35–36 °C, 55–56 °C and 72–74 °C decreased with the increase of MPCM content, and the decrease was the highest when the temperature level was 55–56 °C. Moreover, the compressive strength, flexural strength and density of hardened cement paste decreased with the increase in MPCM content linearly. Among the evaluated properties, the compressive strength of TESCPs had a larger and faster degradation with the increase of MPCM content.

  14. Repeated exposure to conditioned fear stress increases anxiety and delays sleep recovery following exposure to an acute traumatic stressor

    Benjamin N Greenwood


    Full Text Available Repeated stressor exposure can sensitize physiological responses to novel stressors and facilitate the development of stress-related psychiatric disorders including anxiety. Disruptions in diurnal rhythms of sleep-wake behavior accompany stress-related psychiatric disorders and could contribute to their development. Complex stressors that include fear-eliciting stimuli can be a component of repeated stress experienced by humans, but whether exposure to repeated fear can prime the development of anxiety and sleep disturbances is unknown. In the current study, adult male F344 rats were exposed to either control conditions or repeated contextual fear conditioning for 22 days followed by exposure to either no, mild (10, or severe (100 acute uncontrollable tail shock stress. Exposure to acute stress produced anxiety-like behavior as measured by a reduction in juvenile social exploration and exaggerated shock-elicited freezing in a novel context. Prior exposure to repeated fear enhanced anxiety-like behavior as measured by shock-elicited freezing, but did not alter social exploratory behavior. The potentiation of anxiety produced by prior repeated fear was temporary; exaggerated fear was present 1 day but not 4 days following acute stress. Interestingly, exposure to acute stress reduced REM and NREM sleep during the hours immediately following acute stress. This initial reduction in sleep was followed by robust REM rebound and diurnal rhythm flattening of sleep / wake behavior. Prior repeated fear extended the acute stress-induced REM and NREM sleep loss, impaired REM rebound, and prolonged the flattening of the diurnal rhythm of NREM sleep following acute stressor exposure. These data suggest that impaired recovery of sleep / wake behavior following acute stress could contribute to the mechanisms by which a history of prior repeated stress increases vulnerability to subsequent novel stressors and stress-related disorders.

  15. Improvement of the redox balance increases L-valine production by Corynebacterium glutamicum under oxygen deprivation conditions.

    Hasegawa, Satoshi; Uematsu, Kimio; Natsuma, Yumi; Suda, Masako; Hiraga, Kazumi; Jojima, Toru; Inui, Masayuki; Yukawa, Hideaki


    Production of L-valine under oxygen deprivation conditions by Corynebacterium glutamicum lacking the lactate dehydrogenase gene ldhA and overexpressing the L-valine biosynthesis genes ilvBNCDE was repressed. This was attributed to imbalanced cofactor production and consumption in the overall L-valine synthesis pathway: two moles of NADH was generated and two moles of NADPH was consumed per mole of L-valine produced from one mole of glucose. In order to solve this cofactor imbalance, the coenzyme requirement for L-valine synthesis was converted from NADPH to NADH via modification of acetohydroxy acid isomeroreductase encoded by ilvC and introduction of Lysinibacillus sphaericus leucine dehydrogenase in place of endogenous transaminase B, encoded by ilvE. The intracellular NADH/NAD(+) ratio significantly decreased, and glucose consumption and L-valine production drastically improved. Moreover, L-valine yield increased and succinate formation decreased concomitantly with the decreased intracellular redox state. These observations suggest that the intracellular NADH/NAD(+) ratio, i.e., reoxidation of NADH, is the primary rate-limiting factor for L-valine production under oxygen deprivation conditions. The L-valine productivity and yield were even better and by-products derived from pyruvate further decreased as a result of a feedback resistance-inducing mutation in the acetohydroxy acid synthase encoded by ilvBN. The resultant strain produced 1,470 mM L-valine after 24 h with a yield of 0.63 mol mol of glucose(-1), and the L-valine productivity reached 1,940 mM after 48 h.

  16. Presynaptic transporter-mediated release of glutamate evoked by the protonophore FCCP increases under altered gravity conditions

    Borisova, T. A.; Krisanova, N. V.


    High-affinity Na +-dependent glutamate transporters of the plasma membrane mediate the glutamate uptake into neurons, and thus maintain low levels of extracellular glutamate in the synaptic cleft. The study focused on the release of glutamate by reversal of Na +-dependent glutamate transporters from rat brain nerve terminals (synaptosomes) under conditions of centrifuge-induced hypergravity. Flow cytometric analysis revealed similarity in the size and cytoplasmic granularity between synaptosomal preparations obtained from control and G-loaded animals (10 G, 1 h). The release of cytosolic L-[ 14C]glutamate from synaptosomes was evaluated using the protonophore FCCP, which dissipated synaptic vesicle proton gradient, thus synaptic vesicles were not able to keep glutamate inside and the latter enriched cytosol. FCCP per se induced the greater release of L-[ 14C]glutamate in hypergravity as compared to control (4.8 ± 1.0% and 8.0 ± 1.0% of total label). Exocytotic release of L-[ 14C]glutamate evoked by depolarization was reduced down to zero after FCCP application under both conditions studied. Depolarization stimulated release of cytosolic L-[ 14C]glutamate from synaptosomes preliminary treated with FCCP was considerably increased from 27.0 ± 2.2% of total label in control to 35.0 ± 2.3% in hypergravity. Non-transportable inhibitor of glutamate transporter DL-threo-β-benzyloxyaspartate was found to significantly inhibit high-KCl and FCCP-stimulated release of L-[ 14C]glutamate, confirming the release by reversal of glutamate transporters. The enhancement of transporter-mediated release of glutamate in hypergravity was found to result at least partially from the inhibition of the activity of Na/K-ATPase in the plasma membrane of synaptosomes. We suggested that hypergravity-induced alteration in transporter-mediated release of glutamate indicated hypoxic injury of neurons.

  17. Strain Hardening and Size Effect in Five-fold Twinned Ag Nanowires.

    Narayanan, Sankar; Cheng, Guangming; Zeng, Zhi; Zhu, Yong; Zhu, Ting


    Metallic nanowires usually exhibit ultrahigh strength but low tensile ductility owing to their limited strain hardening capability. Here we study the unique strain hardening behavior of the five-fold twinned Ag nanowires by nanomechanical testing and atomistic modeling. In situ tensile tests within a scanning electron microscope revealed strong strain hardening behavior of the five-fold twinned Ag nanowires. Molecular dynamics simulations showed that such strain hardening was critically controlled by twin boundaries and pre-existing defects. Strain hardening was size dependent; thinner nanowires achieved more hardening and higher ductility. The size-dependent strain hardening was found to be caused by the obstruction of surface-nucleated dislocations by twin boundaries. Our work provides mechanistic insights into enhancing the tensile ductility of metallic nanostructures by engineering the internal interfaces and defects.

  18. Effect of increasing levels of nitrogen on yield of tea in different agro-ecological conditions of Pakistan

    F.S. Hamid; Tahira Ahmad


    Field experiment was conducted on mature tea bushes of Qi-Men variety at two different altitudes from sealevel i.e. at National Tea Research Institute Shinkiari (1000 m) and on farmer's field in Konsh valley at village Battal (1500m). Different levels of nitrogen with constant dose of phosphorus and potassium were applied to observe the optimal dose of nutrients for highest yield under local edaphic conditions. The experiment was repeated for three consecutive years.The highest yield of fresh tea leaves were obtained by the application of 420 kg ha-1 N followed by the application of 360kg ha-1 N at 1000 masl. The highest dose of nitrogen also reduced significantly the soil pH in the upper (0-15cm) layer depth during 1998 and 1999. During the year 2000, the reduction in soil pH was observed by the application of highest dose of nitrogen but was non-significant at 5% level. The lower soil depth (15-30 cm) showed the reduction in pH with the highest dose of nitrogen during the experimental year but was statistically non significant.At the higher altitude of 1500 masi the highest yield of fresh tea leaves was obtained by the application of 420 kg ha-1during the experimental years but the increase was significant during the year 1999 and 2000. The yield of the fresh tea leaves was positively correlated with the amount of nitrogen application at both the altitudes. The increasing amount of nitrogen decreased the soil pH at both the depths of 0-15cm and 15-30cm. Unlike the lower altitude (1000 m) there was no any significant reduction in the soil pH during 1998 and 1999. A significant reduction in soil pH was found in the year 2000.

  19. Thermal sensation of Hong Kong people with increased air speed, temperature and humidity in air-conditioned environment

    Chow, T.T. [School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Kowloon, Hong Kong SAR (China); Fong, K.F.; Lin, Zhang; Chan, A.L.S. [Division of Building Science and Technology, College of Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Kowloon, Hong Kong SAR (China); Givoni, B. [Department of Architecture, UCLA, Los Angeles, CA (United States); BGU, Beer Sheva (Israel)


    In the warm and humid climate zone, air-conditioning (AC) is usually provided at working places to enhance human thermal comfort and work productivity. From the building sustainability point of view, to achieve acceptable thermal sensation with the minimum use of energy can be desirable. A new AC design tactic is then to increase the air movement so that the summer temperature setting can be raised. A laboratory-based thermal comfort survey was conducted in Hong Kong with around 300 educated Chinese subjects. Their thermal sensation votes were gathered for a range of controlled thermal environment. The result analysis shows that, like in many other Asian cities, the thermal sensation of the Hong Kong people is sensitive to air temperature and speed, but not much to humidity. With bodily air speed at 0.1-0.2 m/s, clothing level 0.55 clo and metabolic rate 1 met, the neutral temperature was found around 25.4 C for sedentary working environment. Then recommendations are given to the appropriate controlled AC environment in Hong Kong with higher airflow speeds. (author)

  20. Dietary medium- or long-chain triglycerides improve body condition of lean-genotype sows and increase suckling pig growth.

    Gatlin, L Averette; Odle, J; Soede, J; Hansent, J A


    In a field trial conducted on a commercial swine farm, lean-genotype sows (n = 485) were fed diets containing 0 or 10% supplemental fat as either medium-chain triglyceride or choice white grease from d 90 of gestation until weaning (15.5 d). Effects on standard sow and litter production traits were examined together with assessment of sow body condition using live ultrasound. Daily feed intake during lactation was 10% higher in sows consuming diets without added fat (7.2 vs 6.5 kg; P 0.10). Sows supplemented with fat were 4 kg heavier on d 109 of gestation (220 vs 224 kg; P or = 0.10). Longissimus muscle area at weaning was slightly greater (44.96 vs 46.2 cm2) in sows consuming fat than in control sows (P or = 0.10). Gestation length, pigs born alive, average birth weight, survival (d 3 to weaning), and days to estrus were not affected by diet (P > 0.10). However, supplemental fat increased pig ADG (192 vs 203 g/d; P pig weaning weight (4.3 vs 4.5 kg) at 15.5 d (P pig performance without affecting energy intake during lactation, implying improved efficiency of sow energy utilization.

  1. Association of macroscopic laboratory testing and micromechanics modelling for the evaluation of the poroelastic parameters of a hardened cement paste

    Ghabezloo, Siavash


    The results of a macro-scale experimental study performed on a hardened class G cement paste [Ghabezloo et al. (2008) Cem. Con. Res. (38) 1424-1437] are used in association with the micromechanics modelling and homogenization technique for evaluation of the complete set of poroelastic parameters of the material. The experimental study consisted in drained, undrained and unjacketed isotropic compression tests. Analysis of the experimental results revealed that the active porosity of the studied cement paste is smaller than its total porosity. A multi-scale homogenization model, calibrated on the experimental results, is used to extrapolate the poroelastic parameters to cement pastes prepared with different water-to-cement ratio. The notion of cement paste active porosity is discussed and the poroelastic parameters of hardened cement paste for an ideal, perfectly drained condition are evaluated using the homogenization model.

  2. Strain rate dependence of the flow stress and work hardening of {gamma}`

    Ezz, S.S. [Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH (United Kingdom); Sun, Y.Q. [Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH (United Kingdom); Hirsch, P.B. [Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH (United Kingdom)


    The strain rate ({epsilon}) sensitivity of the flow stress ({tau}), {beta}=({delta}{tau}/{delta} ln{epsilon}), of crystals of {gamma}` in the temperature (T) range of the yield stress anomaly obeys a Cottrell-Stokes law when plotted against {tau}{sub h}={tau}-{tau}{sub y}, where {tau}{sub y} is the yield stress at 0.01% strain. The slopes are approximately 1%, decrease with increasing T and are approximately independent of orientation. {tau}{sub h} is due to work hardening and depends on the prestrain {epsilon}, {epsilon} and T. Transmission electron microscopy observations suggest that at 2% strain at 600 K and 720 K, {tau}{sub h} and {beta} are mainly controlled by forest obstacles. At 600 K, the forest consists largely of [101] dislocations on the (010) cross slip plane threading the (111) planes and generated by bowing of the [101] primary screws (Kear-Wilsdorf locks). At 720 K, the forest is non-uniform and consists of [101] on (010), primary cube [110] on (001) and secondary octahedral slip dislocations. At room temperature, the strength of the obstacles is weaker and it is suggested that they are mainly jogs on edge dislocations generated by cross slip of screw segments. At 2% strain, fine slip on (010) and (001) contributes increasingly to strain with increasing T and this correlates with the decrease in the work-hardening rate. ((orig.))

  3. Radiation Hardening of LED Luminaires for Accelerator Tunnels

    Devine, James D


    This paper summarises progress made towards the radiation hardening of LED emergency luminaires for evacuation and emergency response within the underground areas of the CERN accelerator complex. The objective has been to radiation harden existing Commercial Off-The-Shelf (COTS) emergency luminaires to maximise lighting performance, without compromising IEC 60598-2-22 compliance. A systems level approach has been adopted, leading to the development of a diode bridge based AC/DC power converter. Modified COTS luminaires including this converter design have been irradiated (to 100 kGy TID using a Cobalt-60 source), with results of a subsequent photometric analysis presented. Following encouraging tests results, a reference design for the power converter has been released under the CERN Open Hardware License to encourage manufacturer adoption. The paper concludes with areas of interest for future research in further improving the radiation hardness of LED emergency lighting for accelerators with detailed studies...

  4. Segmentation-free empirical beam hardening correction for CT

    Schüller, Sören; Sawall, Stefan [German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg 69120 (Germany); Stannigel, Kai; Hülsbusch, Markus; Ulrici, Johannes; Hell, Erich [Sirona Dental Systems GmbH, Fabrikstraße 31, 64625 Bensheim (Germany); Kachelrieß, Marc, E-mail: [German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany)


    Purpose: The polychromatic nature of the x-ray beams and their effects on the reconstructed image are often disregarded during standard image reconstruction. This leads to cupping and beam hardening artifacts inside the reconstructed volume. To correct for a general cupping, methods like water precorrection exist. They correct the hardening of the spectrum during the penetration of the measured object only for the major tissue class. In contrast, more complex artifacts like streaks between dense objects need other techniques of correction. If using only the information of one single energy scan, there are two types of corrections. The first one is a physical approach. Thereby, artifacts can be reproduced and corrected within the original reconstruction by using assumptions in a polychromatic forward projector. These assumptions could be the used spectrum, the detector response, the physical attenuation and scatter properties of the intersected materials. A second method is an empirical approach, which does not rely on much prior knowledge. This so-called empirical beam hardening correction (EBHC) and the previously mentioned physical-based technique are both relying on a segmentation of the present tissues inside the patient. The difficulty thereby is that beam hardening by itself, scatter, and other effects, which diminish the image quality also disturb the correct tissue classification and thereby reduce the accuracy of the two known classes of correction techniques. The herein proposed method works similar to the empirical beam hardening correction but does not require a tissue segmentation and therefore shows improvements on image data, which are highly degraded by noise and artifacts. Furthermore, the new algorithm is designed in a way that no additional calibration or parameter fitting is needed. Methods: To overcome the segmentation of tissues, the authors propose a histogram deformation of their primary reconstructed CT image. This step is essential for the

  5. Hardening electronic devices against very high total dose radiation environments

    Buchanan, B.; Shedd, W.; Roosild, S.; Dolan, R.


    The possibilities and limitations of hardening silicon semiconductor devices to the high neutron and gamma radiation levels and greater than 10 to the eighth power rads required for the NERVA nuclear engine development are discussed. A comparison is made of the high dose neutron and gamma hardening potential of bipolar, metal insulator semiconductors and junction field effect transistors. Experimental data is presented on device degradation for the high neutron and gamma doses. Previous data and comparisons indicate that the JFET is much more immune to the combined neutron displacement and gamma ionizing effects than other transistor types. Experimental evidence is also presented which indicates that p channel MOS devices may be able to meet the requirements.

  6. Poromechanical behaviour of hardened cement paste under isotropic loading

    Ghabezloo, Siavash; Guédon, Sylvine; Martineau, Francçois; Saint-Marc, Jérémie


    The poromechanical behaviour of hardened cement paste under isotropic loading is studied on the basis of an experimental testing program of drained, undrained and unjacketed compression tests. The macroscopic behaviour of the material is described in the framework of the mechanics of porous media. The poroelastic parameters of the material are determined and the effect of stress and pore pressure on them is evaluated. Appropriate effective stress laws which control the evolution of total volume, pore volume, solid volume, porosity and drained bulk modulus are discussed. A phenomenon of degradation of elastic properties is observed in the test results. The microscopic observations showed that this degradation is caused by the microcracking of the material under isotropic loading. The good compatibility and the consistency of the obtained poromechanical parameters demonstrate that the behaviour of the hardened cement paste can be indeed described within the framework of the theory of porous media.


    HUYing-ning; WANGCheng-yong; WUXue-qi; QINZhe; ZENGBao-ping


    Tool wear and breakage of the micro-milling tool is an important problem for high speed machining of hardened steel die and mould. Dry milling of S136 hardened steel is carried out using TiA1N coated carbide micro-end mill (Ф2 mm). The effect of cutting speed, feed per tooth and radial depth of cut on cutting force is analyzed. Cutting parameters adapting to dry machining and strategy optimized for higher rate of material removal with lower cutting force are attained. Results of SEM observation show that the main failure patterns of micro-end mill are breakage of tool tip, wear and drop-off of surface coating, micro-chipping, and breakage of flank.

  8. Sequential circuit design for radiation hardened multiple voltage integrated circuits

    Clark, Lawrence T.; McIver, III, John K.


    The present invention includes a radiation hardened sequential circuit, such as a bistable circuit, flip-flop or other suitable design that presents substantial immunity to ionizing radiation while simultaneously maintaining a low operating voltage. In one embodiment, the circuit includes a plurality of logic elements that operate on relatively low voltage, and a master and slave latches each having storage elements that operate on a relatively high voltage.

  9. Reduction of metal artifacts: beam hardening and photon starvation effects

    Yadava, Girijesh K.; Pal, Debashish; Hsieh, Jiang


    The presence of metal-artifacts in CT imaging can obscure relevant anatomy and interfere with disease diagnosis. The cause and occurrence of metal-artifacts are primarily due to beam hardening, scatter, partial volume and photon starvation; however, the contribution to the artifacts from each of them depends on the type of hardware. A comparison of CT images obtained with different metallic hardware in various applications, along with acquisition and reconstruction parameters, helps understand methods for reducing or overcoming such artifacts. In this work, a metal beam hardening correction (BHC) and a projection-completion based metal artifact reduction (MAR) algorithms were developed, and applied on phantom and clinical CT scans with various metallic implants. Stainless-steel and Titanium were used to model and correct for metal beam hardening effect. In the MAR algorithm, the corrupted projection samples are replaced by the combination of original projections and in-painted data obtained by forward projecting a prior image. The data included spine fixation screws, hip-implants, dental-filling, and body extremity fixations, covering range of clinically used metal implants. Comparison of BHC and MAR on different metallic implants was used to characterize dominant source of the artifacts, and conceivable methods to overcome those. Results of the study indicate that beam hardening could be a dominant source of artifact in many spine and extremity fixations, whereas dental and hip implants could be dominant source of photon starvation. The BHC algorithm could significantly improve image quality in CT scans with metallic screws, whereas MAR algorithm could alleviate artifacts in hip-implants and dentalfillings.

  10. Effect of Welding Speed on Mechanical Properties and the Strain-Hardening Behavior of Friction Stir Welded 7075 Aluminum Alloy Joints

    Xu, Weifeng; Li, Zhaoxi; Sun, Xiaohong


    The effect of welding speed on the microstructural evolution, mechanical properties and strain-hardening behavior of friction stir welded (FSWed) high-strength AA7075-T651 was investigated. Large intermetallic particles and grains, whose sizes increased at lower welding speeds, were present in the heat-affected zone. FSWed joints fabricated at the higher welding speed or lower strain rates exhibited higher strength, joint efficiency and ductility than those fabricated at lower welding speeds or higher strain rates. A maximum joint efficiency of 97.5% and an elongation to failure of 15.9% were obtained using a welding speed of 400 mm/min at a strain rate of 10-5 s-1. The hardening capacity, strain-hardening exponent and strain-hardening rate of the FSWed joints were significantly higher than those of the base material, but materials exhibited stage III and stage IV hardening characteristics. The results morphology of the fracture surfaces is consistent with the above results.

  11. Effect of cysteine on lowering protein aggregation and subsequent hardening of whey protein isolate (WPI) protein bars in WPI/buffer model systems.

    Zhu, Dan; Labuza, Theodore P


    Whey protein isolate (WPI) bar hardening without and with cysteine (Cys) or N-ethylmaleimide (NEM) was investigated in model systems (WPI/buffer = 6:4, by weight, pH 6.8, a(w) approximately 0.97) in an accelerated shelf-life test (ASLT) at 45 degrees C over a period of up to 35 days. The formation of insoluble aggregates as determined by solubility and the structural rearrangement of WPI protein aggregates as observed by SEM were responsible for the WPI bars' hardening. As corroborated by electrophoresis analysis, both beta-lactoglobulin (beta-lg) and alpha-lactalbumin (alpha-la) were involved in the formation of aggregates via the thiol-disulfide interchange reaction and/or noncovalent interactions. The former force dominated the bar hardening at an earlier stage, whereas the latter force played a role for the long-term hardening. In comparison with the control bar without Cys, the thiol-disulfide interchange reaction was significantly reduced by Cys (WPI/Cys = 0.05), increased by Cys (WPI/Cys = 0.25), and inhibited by NEM (WPI/NEM = 2). Therefore, bar hardening was significantly delayed by Cys (WPI/Cys = 0.05) and NEM but accelerated by Cys (WPI/Cys = 0.25).

  12. Precipitation hardening of biodegradable Fe-Mn-Pd alloys

    Moszner, F. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Sologubenko, A.S. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Laboratory for Nanometallurgy, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Schinhammer, M. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Lerchbacher, C. [Christian Doppler Laboratory for Early Stages of Precipitation, University of Leoben, Franz-Josef-Strasse 18, 8700 Leoben (Austria); Haenzi, A.C. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Leitner, H. [Christian Doppler Laboratory for Early Stages of Precipitation, University of Leoben, Franz-Josef-Strasse 18, 8700 Leoben (Austria); Uggowitzer, P.J. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Loeffler, J.F., E-mail: [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland)


    This work presents a phenomenological description of the precipitation controlled hardening of a new biodegradable Fe-based alloy developed to fulfill the requirements of temporary implant applications. Pronounced strengthening of the solution-treated martensitic Fe-10Mn-1Pd (in wt.%) alloy upon isothermal aging at temperatures within the ferrite-austenite phase field is observed and attributed to the thermally activated formation of coherent plate-like Pd-rich precipitates on {l_brace}1 0 0{r_brace} planes of the matrix. The onset and the early stages of alloy decomposition were studied using two complementary techniques: transmission electron microscopy and three-dimensional atom probe analysis. Three distinct regions of the hardening kinetics are recognized and closely correlated to the evolution of the alloy microstructure. Upon aging, clustering of Pd atoms within the Fe-Mn solid solution occurs. The very small clusters grow, coarsen and adopt a plate-like shape, rearranging mutually to reduce the overall elastic strain energy. The elastic interaction of the dislocation substructure with Pd-rich precipitates of evolving morphology affects the dislocation mobility and is responsible for the hardness evolution of the alloy. A study of the hardening kinetics shows that the process exhibits all the features characteristic of maraging steels.

  13. Multi-material linearization beam hardening correction for computed tomography.

    Lifton, J J


    Since beam hardening causes cupping and streaking artifacts in computed tomographic images, the presence of such artifacts can impair both qualitative and quantitative analysis of the reconstructed data. When the scanned object is composed of a single material, it is possible to correct beam hardening artifacts using the linearization method. However, for multi-material objects, an iterative segmentation-based correction algorithm is needed, which is not only computationally expensive, but may also fail if the initial segmentation result is poor. In this study, a new multi-material linearization beam hardening correction method was proposed and evaluated. The new method is fast and implemented in the same manner as a mono-material linearization. The correction takes approximately 0.02 seconds per projection. Although facing a potential disadvantage of requiring attenuation measurements of one of the object's constituent materials, applying the new method has demonstrated its capability for a multi-material workpiece with substantial reduction in both cupping and streaking artifacts. For example, the study showed that the absolute cupping artefacts in steel, titanium and aluminum spheres were reduced from 22%, 20% and 20% to 5%, 1% and 0%, respectively.

  14. Residual stress analysis of drive shafts after induction hardening

    Lemos, Guilherme Vieira Braga; Rocha, Alexandre da Silva; Nunes, Rafael Menezes, E-mail: [Universidade Federal do Rio Grande do Sul (UFRS), Porto Algre, RS (Brazil); Hirsch, Thomas Karl [Stiftung Institut für Werkstofftechnik (IWT), Bremen (Germany)


    Typically, for automotive shafts, shape distortion manifests itself in most cases after the induction hardening by an effect known as bending. The distortion results in a boost of costs, especially due to machining parts in the hardened state to fabricate its final tolerances. In the present study, residual stress measurements were carried out on automotive drive shafts made of DIN 38B3 steel. The samples were selected in consequence of their different distortion properties by an industrial manufacturing line. One tested shaft was straightened, because of the considerable dimensional variation and the other one not. Firstly, the residual stress measurements were carried out by using a portable diffractometer, in order to avoid cutting the shafts and evaluate the original state of the stresses, and afterwards a more detailed analysis was realized by a conventional stationary diffractometer. The obtained results presented an overview of the surface residual stress profiles after induction hardening and displayed the influence of the straightening process on the redistribution of residual stresses. They also indicated that the effects of the straightening in the residual stresses cannot be neglected. (author)

  15. Study on the hardening mechanism of cement asphalt binder


    The hydration and hardening mechanism of cement asphalt binder(CAB) was studied.The early hydration process,hydration products and paste microstructure of CAB made by Portland cement and anionic asphalt emulsion were investigated by calorimetry,X-ray diffraction,and environmental scanning electron microscopy.The early hydration process of CAB can be characterized as 5 stages similar to those of Portland cement.There is no chemical reaction detected between cement and asphalt,hence no new hydration products other than those of Portland cement are produced.The hardening of CAB begins with the hydration of cement.When the hydration of cement comes into the acceleration period and its exothermic rate comes to the maximum,the coalescence of asphalt particles in asphalt emulsion is triggered.In the hardened system of CAB,it was found that the hydration products of cement form the skeleton and are covered by the continuous asphalt film.They formed an interpenetrating network system.The emulsifiers in the asphalt emulsion may retard the hydration process of cement.

  16. Recent developments in turning hardened steels - A review

    Sivaraman, V.; Prakash, S.


    Hard materials ranging from HRC 45 - 68 such as hardened AISI H13, AISI 4340, AISI 52100, D2 STL, D3 STEEL Steel etc., need super hard tool materials to machine. Turning of these hard materials is termed as hard turning. Hard turning makes possible direct machining of the hard materials and also eliminates the lubricant requirement and thus favoring dry machining. Hard turning is a finish turning process and hence conventional grinding is not required. Development of the new advanced super hard tool materials such as ceramic inserts, Cubic Boron Nitride, Polycrystalline Cubic Boron Nitride etc. enabled the turning of these materials. PVD and CVD methods of coating have made easier the production of single and multi layered coated tool inserts. Coatings of TiN, TiAlN, TiC, Al2O3, AlCrN over cemented carbide inserts has lead to the machining of difficult to machine materials. Advancement in the process of hard machining paved way for better surface finish, long tool life, reduced tool wear, cutting force and cutting temperatures. Micro and Nano coated carbide inserts, nanocomposite coated PCBN inserts, micro and nano CBN coated carbide inserts and similar developments have made machining of hardened steels much easier and economical. In this paper, broad literature review on turning of hardened steels including optimizing process parameters, cooling requirements, different tool materials etc., are done.

  17. Relationship Between Bake Hardening, Snoek-Köster and Dislocation-Enhanced Snoek Peaks in Coarse Grained Low Carbon Steel

    Li Weijuan


    Full Text Available In the present work, specimens prepared from coarse grained low carbon steel with different prestrains were baked and then, their bake hardening (BH property and internal friction were determined. TEM was used to characterize the dislocation structure in BH treated samples. The measurements of internal friction in prestrained samples and baked samples were carried out using a multifunctional internal friction apparatus. The results indicate that, in coarse grained low carbon steel, the bake hardening properties (BH values were negative, which were increased by increasing the prestrain from 2 to 5%, and then were decreased by increasing the prestrain from 5 to 10%. In the specimen with prestrain 5%, the BH value reached the maximum value and the height of Snoek-Köster peak was observed to be the maximum alike. With increasing the prestrain, both of the BH value and Snoek-Köster peak heights are similarly varied. It is concluded that Snoek-Köster and dislocation-enhanced Snoek peaks, caused by the interactions between interstitial solute carbon atoms and dislocations, can be used in further development of the bake hardening steels.

  18. Influence of Workpiece Material on Tool Wear Performance and Tribofilm Formation in Machining Hardened Steel

    Junfeng Yuan


    Full Text Available In addition to the bulk properties of a workpiece material, characteristics of the tribofilms formed as a result of workpiece material mass transfer to the friction surface play a significant role in friction control. This is especially true in cutting of hardened materials, where it is very difficult to use liquid based lubricants. To better understand wear performance and the formation of beneficial tribofilms, this study presents an assessment of uncoated mixed alumina ceramic tools (Al2O3+TiC in the turning of two grades of steel, AISI T1 and AISI D2. Both workpiece materials were hardened to 59 HRC then machined under identical cutting conditions. Comprehensive characterization of the resulting wear patterns and the tribofilms formed at the tool/workpiece interface were made using X-ray Photoelectron Spectroscopy and Scanning Electron Microscopy. Metallographic studies on the workpiece material were performed before the machining process and the surface integrity of the machined part was investigated after machining. Tool life was 23% higher when turning D2 than T1. This improvement in cutting tool life and wear behaviour was attributed to a difference in: (1 tribofilm generation on the friction surface and (2 the amount and distribution of carbide phases in the workpiece materials. The results show that wear performance depends both on properties of the workpiece material and characteristics of the tribofilms formed on the friction surface.

  19. Modeling spray/puddle dissolution processes for deep-ultraviolet acid-hardened resists

    Hutchinson, John M.; Das, Siddhartha; Qian, Qi-De; Gaw, Henry T.


    A study of the dissolution behavior of acid-hardened resists (AHR) was undertaken for spray and spray/puddle development processes. The Site Services DSM-100 end-point detection system is used to measure both spray and puddle dissolution data for a commercially available deep-ultraviolet AHR resist, Shipley SNR-248. The DSM allows in situ measurement of dissolution rate on the wafer chuck and hence allows parameter extraction for modeling spray and puddle processes. The dissolution data for spray and puddle processes was collected across a range of exposure dose and postexposure bake temperature. The development recipe was varied to decouple the contribution of the spray and puddle modes to the overall dissolution characteristics. The mechanisms involved in spray versus puddle dissolution and the impact of spray versus puddle dissolution on process performance metrics has been investigated. We used the effective-dose-modeling approach and the measurement capability of the DSM-100 and developed a lumped parameter model for acid-hardened resists that incorporates the effects of exposure, postexposure bake temperature and time, and development condition. The PARMEX photoresist-modeling program is used to determine parameters for the spray and for the puddle process. The lumped parameter AHR model developed showed good agreement with experimental data.

  20. Preparation of in situ hardening composite microcarriers: calcium phosphate cement combined with alginate for bone regeneration.

    Park, Jung-Hui; Lee, Eun-Jung; Knowles, Jonathan C; Kim, Hae-Won


    Novel microcarriers consisting of calcium phosphate cement and alginate were prepared for use as three-dimensional scaffolds for the culture and expansion of cells that are effective for bone tissue engineering. The calcium phosphate cement-alginate composite microcarriers were produced by an emulsification of the composite aqueous solutions mixed at varying ratios (calcium phosphate cement powder/alginate solution = 0.8-1.2) in an oil bath and the subsequent in situ hardening of the compositions during spherodization. Moreover, a porous structure could be easily created in the solid microcarriers by soaking the produced microcarriers in water and a subsequent freeze-drying process. Bone mineral-like apatite nanocrystallites were shown to rapidly develop on the calcium phosphate cement-alginate microcarriers under moist conditions due to the conversion of the α-tricalcium phosphate phase in the calcium phosphate cement into a carbonate-hydroxyapatite. Osteoblastic cells cultured on the microspherical scaffolds were proven to be viable, with an active proliferative potential during 14 days of culture, and their osteogenic differentiation was confirmed by the determination of alkaline phosphatase activity. The in situ hardening calcium phosphate cement-alginate microcarriers developed herein may be used as potential three-dimensional scaffolds for cell delivery and tissue engineering of bone.

  1. Dissolution of hardened wood ash in forest soils. Studies in a column experiment; Haerdade vedaskors upploesning i skogsjord. En studie i kolonnfoersoek. Ramprogram Askaaterfoering

    Eriksson, Jan [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dept. of Soil Sciences


    Dissolution of hardened and crushed ashes was studied in a column experiment during leaching with artificial rain water corresponding to 5 year-precipitations. The ashes studied were a CFB ash from Perstorp and a bottom ash from Ljungby that were added in amounts corresponding to 4 tonnes per hectare. Assuming that the studied ashes are representative and that the results can be transferred to field conditions, the most important conclusions that can be drawn are summarized in the following way: Hardened and crushed ashes are broken down relatively slowly, which particularly applies to the coarse fraction. The fine fraction of the Perstorp ashes has a good liming effect at the same time as the risk for large pH-increases appears to be small. As regards the macro-nutrients Ca and K (not the Ljungby ashes), the amounts released are probably sufficient from a forest vitalization viewpoint. As regards Mg and P, this is less certain. The heavy metals appear to be released relatively slowly and most of them are bound in non-exchangeable form in the mor layer. The exception is Cd that tends to be absorbed in the mor layer to a minor extent but which, on the other hand, is not released from the ashes in any greater amounts. The greatest risk for increased concentrations of soluble heavy metals appears to be the mobilization of part of the mor layer`s reserve as a result of the salt effect of the ashes. However, this is a temporary effect. 17 refs, 18 figs, 6 tabs Figs and tabs with text in English

  2. Short-term sleep loss decreases physical activity under free-living conditions but does not increase food intake under time-deprived laboratory conditions in healthy men

    Schmid, Sebastian M; Hallschmid, Manfred; Jauch-Chara, Kamila; Wilms, Britta; Benedict, Christian; Lehnert, Hendrik; Born, Jan; Schultes, Bernd


    .... We aimed to test the hypothesis that acute sleep loss decreases physical activity while increasing food intake, thereby shifting 2 crucial behavioral components of energy homeostasis toward weight gain...

  3. Theoretical analysis of the conditions for increasing the accuracy of the axial hole machining multiple tip tools

    Т. М. Брижан


    Full Text Available This paper deals with the development of a mathematical model for determining the value of the elastic displacement that occurs when reaming and deployment of holes. The lack of theoretical studies of the analytical representation of the cutting force limits the study of conditions to improve the accuracy of hole machining. A promising direction should be considered a theoretical approach, which allows to determine the magnitude of the elastic displacement occurring in the technological system when drilling and thus to estimate the error handling holes. A further development of this approach is a theoretical analysis of the magnitude of the elastic displacement that occurs when processing multiple tip tools axial holes (core drills and reamers. In this paper, based on the analytic representation of cutting forces in machining holes axial multiple tip tools have received a new theoretical solution of the nature of changes in the magnitude of the elastic displacement occurring in the technological system and determining error processing holes. Calculations revealed, that in the case of misalignment of the hole axis tool with four or more blades magnitude of the elastic displacement remains constant, regardless of the position of the blades. However, the torque varies cyclically, giving rise to a torsional oscillation process system. Proved, that with increasing amounts of the variable part of the tool blades torque decreases. It follows from this promising application of axial multiple tip tools (reamers, reamers with inclined blades, so as to avoid the time variation of torque and thus eliminate torsional vibrations in the technological system, that is essential for improving the accuracy of hole machining and surface finish class


    A. Tomczak


    Full Text Available The aim of the study was to define the changes of the characteristics of physiological postural tremor under conditions of increasing fatigue and lack of sleep during prolonged military training (survival.The subjects of the study were 15 students of the Polish Air Force Academy in Dęblin. The average age was 19.9±1.3 years. During the 36-hour-long continuous military training (survival the subjects were deprived of sleep. Four tremor measurements were carried out for each of the subjects: Day 1 – morning, after rest (measurement 0; Day 2 – morning, after overnight physical exercise (measurement 1; afternoon, after continuous sleep deprivation (measurement 2; Day 3 – morning, after a full night sleep (measurement 3. The accelerometric method using an acceleration measuring kit was applied to analyse tremor. A significant difference between mean values of the index evaluating tremor power in low frequencies L2-4 in measurement 0 and measurement 3 was observed (p<0.01. No significant differences were found in mean values of index L10-20. Mean frequencies F2-4 differed significantly from each other (F 2,42 =4.53; p<0.01. Their values were 2.94±0.11, 2.99±0.9, 2.93±0.07 and 2.91±0.07 for successive measurements. A gradual, significant decrease of F 8-14 was observed (F 2,42 =5.143; p<0.01. Prolonged sleep deprivation combined with performing tasks demanding constant physical effort causes long-lasting (over 24 hours changes of the amplitude of low-frequency tremor changes. This phenomenon may significantly influence psychomotor performance, deteriorating the ability to perform tasks requiring movement precision.

  5. Co-effect of increased humidity and meteorological conditions on greenhouse gas fluxes in a young hybrid aspen forest

    Hansen, Raili; Mander, Ülo; Kupper, Priit; Soosaar, Kaido; Maddison, Martin; Sõber, Jaak; Lõhmus, Krista


    Due to the climate change, higher precipitation and an increase in air humidity is expected in northern Europe in the near future (IPCC 2007). There are some studies about irrigation, elevated CO2 and O3 etc., but still we have too little knowledge about the humidity effect on the deciduous forest ecosystem. In 2006 a free-air humidity manipulation (FAHM) facility was established in Estonia and in 2008 we started to artificially increase the air humidity in young hybrid aspen (Populus tremula L. x P. tremuloides Michx.) forest trials on an Endogleyic Planosol of former arable land. Air humidity was raised on average about 7% compared to ambient condition (Tullus et al., 2012). We measured the carbon dioxide, methane and nitrous oxide fluxes from the FAHM system using closed static chamber and gas-chromatograph techniques from July 2009 to November 2012 during snow free periods. Flux measurements were done once a month in three humidification (h) plots and in three control (c) plots. We monitored soil temperature, soil water potential (SWP), precipitation and relative humidity. The vegetation period was rainy in 2009, droughty in 2010 and 2011 (according to SWP the drought was severe in 2011) and cold in 2012. Soil respiration was the lowest in 2011 both in c and h plots; however it was significantly higher in h. Most of the time the soil was a sink for methane, but less CH4 was oxidized in the soil of h plots. Emission of N2O did not have good correlation with air humidity, although one could observe a clear tendency of bigger N2O fluxes when soil was continuously water-saturated. Expectedly, soil respiration had strong positive correlations with soil temperature and CH4 emission demonstrated strong positive correlation with SWP. Hence, interaction of humidification and precipitation affected greenhouse gas fluxes. IPCC, Climate Change 2007: The Physical Science Basis. Cambridge University Press, Cambridge. 2007. Tullus A, Kupper P, Sellin A, Parts L, Sõber J

  6. Spherical nanoindentation of proton irradiated 304 stainless steel: A comparison of small scale mechanical test techniques for measuring irradiation hardening

    Weaver, Jordan S.; Pathak, Siddhartha; Reichardt, Ashley; Vo, Hi T.; Maloy, Stuart A.; Hosemann, Peter; Mara, Nathan A.


    Experimentally quantifying the mechanical effects of radiation damage in reactor materials is necessary for the development and qualification of new materials for improved performance and safety. This can be achieved in a high-throughput fashion through a combination of ion beam irradiation and small scale mechanical testing in contrast to the high cost and laborious nature of bulk testing of reactor irradiated samples. The current work focuses on using spherical nanoindentation stress-strain curves on unirradiated and proton irradiated (10 dpa at 360 °C) 304 stainless steel to quantify the mechanical effects of radiation damage. Spherical nanoindentation stress-strain measurements show a radiation-induced increase in indentation yield strength from 1.36 GPa to 2.72 GPa and a radiation-induced increase in indentation work hardening rate of 10 GPa-30 GPa. These measurements are critically compared against Berkovich nanohardness, micropillar compression, and micro-tension measurements on the same material and similar grain orientations. The ratio of irradiated to unirradiated yield strength increases by a similar factor of 2 when measured via spherical nanoindentation or Berkovich nanohardness testing. A comparison of spherical indentation stress-strain curves to uniaxial (micropillar and micro-tension) stress-strain curves was achieved using a simple scaling relationship which shows good agreement for the unirradiated condition and poor agreement in post-yield behavior for the irradiated condition. The disagreement between spherical nanoindentation and uniaxial stress-strain curves is likely due to the plastic instability that occurs during uniaxial tests but is absent during spherical nanoindentation tests.

  7. An Evaluation of the Corrosion and Mechanical Performance of Interstitially Surface-Hardened Stainless Steel

    Jones, Jennifer L.; Koul, Michelle G.; Schubbe, Joel J.


    A surface hardening technique called "interstitial hardening" is commercially available, whereby interstitial carbon atoms are introduced into stainless steel surfaces without the formation of carbides. Surface hardening of machine elements such as impellors or fasteners would improve performance regarding cavitation and galling resistance, and has intensified interest in this process. However, there remains a need to characterize and validate the specific performance characteristics of the hardened materials. This paper describes experimental testing conducted on 316L stainless steel that has been surface hardened using available commercial techniques, using carbon as the interstitial atom. The corrosion performance of the hardened surface is assessed using electrochemical potentiodynamic testing to determine the breakdown potential in 3.5 wt.% NaCl solution to identify the most promising method. The hardness and thickness of the surface-hardened layer is characterized and compared using metallography and microhardness profiling. Corrosion fatigue and slow strain rate testing of untreated, hardened, and damaged, hardened surfaces exposed to ASTM seawater is conducted. Finally, critical galling stresses are determined and compared. Post-test examination of damage attempts to identify mechanisms of material failure and characterize how corrosion-assisted cracks initiate and grow in surface-hardened materials.

  8. Analytical calculation of the hardening depth of laser surface hardening ductile cast iron%球墨铸铁激光表面淬火硬化深度的解析计算

    颜丙功; 刘继常; 郭怡晖


    In order to obtain the hardening depth that treated with laser surface hardening simply and immediately, the process of laser surface hardening was analyzed and an analytical equation was concluded based on the semi-infinite surface point heat thermal diffusion equation, at the same time the experiment was conducted and ideal results were obtained. The method is right and efficient verified by the experimental results under existing experimental conditions.%为了简单快速地得到激光表面淬火的硬化深度,利用激光加热过程中的半无限体表面点热源热扩散公式,在分析激光表面淬火相变硬化基本规律的基础上,对激光表面淬火硬化层深度的解析计算公式进行了推导和试验验证,并取得了较为理想的数据.结果表明,在现有试验条件下该计算方法是高效和正确的.

  9. 普洱茶渥堆过程中的板结机理研究%Harden Mechanism Research During Pile-Fermentation Processing of Pu’er Tea

    向正坤; 杨永发


    普洱茶渥堆发酵过程中容易出现板结现象。板结的产生不利于普洱茶的发酵,也给后期的翻堆工艺带来了难度。结合实际问题,通过研究普洱茶的成分变化及发酵环境,得出板结的因素有两点:第一点,发酵过程中产生了水溶性果胶,其具有一定的粘接力;第二点,茶叶在发酵过程中产生弹塑性变形,形成了内摩擦力。最后,通过实验验证了普洱茶发酵中的板结机理,得到对应样本的水溶性果胶粘度值。%Pu’er tea is easy to harden during pile-fermentation processing.Pu'er tea production of harden against pu’er tea fermentation and double pile of increasing difficulty in the later.Combined with practical problems ,and there are two factors through the study of composition and fermentation conditions of pu'er tea: in the first,water-soluble pectin produced in the fermentation process and has a certain sticky relay;then,tea produced elastic and plastic deformationin during pile-fermentation processing and internal friction force.The pu’er tea fermentation of harden mechanism is verified by experiment,and get the corresponding sample viscosity values of the water solu-ble pectin.

  10. The transition from stress softening to stress hardening under cyclic loading induced by magnetic field for magneto-sensitive polymer gels

    Xu, Yangguang; Liao, Guojiang; Zhang, Canyang; Wan, Qiang; Liu, Taixiang


    Magneto-sensitive polymer gel (MSPG) is a kind of ferromagnetic particle filled smart polymer composite, whose magneto-mechanical coupling mechanism has attracted increasing attention in recent years. In this work, the magneto-induced rheological response of MSPG under cyclic shear loading was investigated. It was found that magnetic field is the critical reason for the transition from stress softening to stress hardening under cyclic loading. Besides, the particle concentration and temperature are the controlling factors in the structure optimization of MSPG in the presence of magnetic field. The magneto-induced hardening mechanism was further proposed based on the related experimental results.

  11. 硬齿面TI蜗杆副的研制与试验研究%A Study on Manufacture and Experiment of Hardened TI Worm Gearing

    孙月海; 卢华武; 杨文彦; 李国营


    TI蜗杆传动由渐开线斜齿轮和其包络的环面蜗杆组成.按照有关TI蜗杆传动主要设计参数选择方法的研究结果,给出一对TI蜗杆传动副的具体设计参数,利用研制的砂轮修整器和专用磨头,在滚齿机上实现了TI蜗杆齿面的磨削加工,完成了钢一钢配对的硬齿面副TI蜗杆减速器的制造.采用两种常用的工业润滑油,开展了硬齿面副TI蜗杆传动性能试验,重点测试了蜗杆传动的输入输出转矩、油池温度、运转时间和箱体振动值,对蜗杆传动效率及其影响因素进行分析.结果表明,硬齿面副TI蜗杆减速器在较低的载荷下具有较好的机械传动性能,但随着载荷的增加,齿面间摩擦磨损加剧,传动稳定性下降,含极压添加剂的润滑油对硬齿面的TI蜗杆传动具有较好的润滑效果.%TI worm gearing consists of involute helical gear and its enveloping hourglass worm. According to the previous research result of the parameter choice method of the worm gearing design, the design parameters for TI worm gearing are given. By utilizing a grinding wheel dresser and a special grinding head, the grinding process for TI worm tooth surface is realized on gear-hobbing machine. The hardened TI worm gearbox reducer is made with steel wheel teeth. Experimental research for testing transmission performance is carried out with two kinds of industrial lubricating oil. The input and output torques, box oil temperature, driving time and box vibration are measured. The worm transmission efficiency and its effect factors are analyzed. Test results show that the TI worm gearing reducer with hardened teeth has good transmission performance while the load is in low condition, the tooth friction wear becomes severe and transmission stability declines with the increase of load, and the lubricating oil with extreme pressure additive has good lubricating effect on the hardened TI worm gearing.

  12. Reduced miR-659-3p levels correlate with progranulin increase in hypoxic conditions: implications for frontotemporal dementia.

    Paola ePiscopo


    Full Text Available Progranulin (PGRN is a secreted protein expressed ubiquitously throughout the body, including the brain, where it localizes in neurons and activated microglia. Loss-of-function mutations in the GRN gene are an important cause of familial Frontotemporal Lobar Degeneration (FTLD. PGRN has a neurotrophic and anti-inflammatory activity, and it is neuroprotective in several injury conditions, such as oxygen or glucose deprivation, oxidative injury, and hypoxic stress. Indeed, we have previously demonstrated that hypoxia induces the up-regulation of GRN transcripts. Several studies have shown microRNAs involvement in hypoxia. Moreover, in FTLD patients with a genetic variant of GRN (rs5848, the reinforcement of miR-659-3p binding site has been suggested to be a risk factor. Here, we report that miR-659-3p interacts directly with GRN 3’UTR as shown by luciferase assay in HeLa cells and ELISA and Western Blot analysis in HeLa and Kelly cells. Moreover, we demonstrate the physical binding between GRN mRNA and miR-659-3p employing a miRNA capture-affinity technology in SK-N-BE and Kelly cells. In order to study miRNAs involvement in hypoxia-mediated up-regulation of GRN, we evaluated miR-659-3p levels in SK-N-BE cells after 24h of hypoxic treatment, finding them inversely correlated to GRN transcripts. Furthermore, we analyzed an animal model of asphyxia, finding that GRN mRNA levels increased at post-natal day (pnd 1 and pnd 4 in rat cortices subjected to asphyxia in comparison to control rats and miR-659-3p decreased at pnd 4 just when GRN reached the highest levels. Our results demonstrate the interaction between miR-659-3p and GRN transcript and the involvement of miR-659-3p in GRN up-regulation mediated by hypoxic/ischemic insults.

  13. Disaster-hardened imaging POD for PACS

    Honeyman-Buck, Janice; Frost, Meryll


    After the events of 9/11, many people questioned their ability to keep critical services operational in the face of massive infrastructure failure. Hospitals increased their backup and recovery power, made plans for emergency water and food, and operated on a heightened alert awareness with more frequent disaster drills. In a film-based radiology department, if a portable X-ray unit, a CT unit, an Ultrasound unit, and an film processor could be operated on emergency power, a limited, but effective number of studies could be performed. However, in a digital department, there is a reliance on the network infrastructure to deliver images to viewing locations. The system developed for our institution uses several imaging PODS, a name we chose because it implied to us a safe, contained environment. Each POD is a stand-alone emergency powered network capable of generating images and displaying them in the POD or printing them to a DICOM printer. The technology we used to create a POD consists of a computer with dual network interface cards joining our private, local POD network, to the hospital network. In the case of an infrastructure failure, each POD can and does work independently to produce CTs, CRs, and Ultrasounds. The system has been tested during disaster drills and works correctly, producing images using equipment technologists are comfortable using with very few emergency switch-over tasks. Purpose: To provide imaging capabilities in the event of a natural or man-made disaster with infrastructure failure. Method: After the events of 9/11, many people questioned their ability to keep critical services operational in the face of massive infrastructure failure. Hospitals increased their backup and recovery power, made plans for emergency water and food, and operated on a heightened alert awareness with more frequent disaster drills. In a film-based radiology department, if a portable X-ray unit, a CT unit, an Ultrasound unit, and an film processor could be

  14. Characterization of Tensile Strain Hardening Behaviors for 32Mn-7Cr-1Mo-0.3N Cryogenic Austenitic Steel

    Liang QIU; Ruidong FU; Cunyu WANG; Yangzeng ZHENG


    The strain hardening behaviors of 32Mn-7Cr-1Mo-0.3N austenitic steel were characterized by a simple and effective method. The results show that Hollomon relationship is not applicable during total uniform deformation stage. The flow equation was proposed, Inσ=aexp(lnε/b)+c. The variation rates of strain hardening exponents with true strain at 77 K are obviously higher than that at other temperatures and the value of d2σ/dε2 becomes positive during high strain stage. The characters of this variation are principal reasons for increasing elongation at 77 K. The forming of mechanical twin as well as ε-martensite leads to a high elongation at 77 K.

  15. Influence of cold rolling degree and ageing treatments on the precipitation hardening of 2024 and 7075 alloys

    Naimi, A.; Yousfi, H.; Trari, M.


    In the present work, the precipitation hardening of 2024 and 7075 aluminum alloys is investigated as a function of cold rolling degree, ageing time and temperature using Vickers microhardness measurements and differential scanning calorimetry (DSC). It is found that a variation in such parameters can improve the hardness and plays an important role in the precipitation hardening process. At specific ageing temperature, the large cold rolled 7075 alloy exhibits two peaks of hardness. Moreover, for both alloys, the increment of hardness during ageing decreases with increasing the cold rolling degree. While in some cases microhardness measurements give impression that the precipitation reaction is slowed down by deformation, DSC analysis indicates that the precipitation is much accelerated since only a slight deformation decreases strongly the temperatures of reactions. However, the degree of cold rolling does not play a crucial role.

  16. Cyclic uniaxial and biaxial hardening of type 304 stainless steel modeled by the viscoplasticity theory based on overstress

    Yao, David; Krempl, Erhard


    The isotropic theory of viscoplasticity based on overstress does not use a yield surface or a loading and unloading criterion. The inelastic strain rate depends on overstress, the difference between the stress and the equilibrium stress, and is assumed to be rate dependent. Special attention is paid to the modeling of elastic regions. For the modeling of cyclic hardening, such as observed in annealed Type 304 stainless steel, and additional growth law for a scalar quantity which represents the rate independent asymptotic value of the equilibrium stress is added. It is made to increase with inelastic deformation using a new scalar measure which differentiates between nonproportional and proportional loading. The theory is applied to correlate uniaxial data under two step amplitude loading including the effect of further hardening at the high amplitude and proportional and nonproportional cyclic loadings. Results are compared with corresponding experiments.

  17. The investigation of the deformation wave hardening effect on the strength of the medium and low alloy steels

    Kirichek, A. V.; Barinov, S. V.; Yashin, A. V.; Kolontsov, S. E.


    The article presents the data on the effect of wave deformation hardening on the strength of the 45, 40X and 35 HGSA steel. To improve the strength of these steels, it is proposed to create structured areas consisting of alternating solid and viscous-plastic sections in their surface layer. The evenness of arrangement of the sections is characterized by the overlap factor. The studies found that wave deformation treatment of the samples, made of the 45, 40X 35HGSA steel, made it possible to increase the tensile strength by 8, 4.2 and 13%, the values of elastic deformations - by 37, 81 and 51% during their hardening with overlapping coefficients 0.7; 0.9 and 0.7, respectively.

  18. Hardening of the national flower of Colombia, the threatened Cattleya trianae (Orchidaceae), from in vitro culture with previous invigoration phase.

    Franco, Marcela; Guevara, Giovany; Mesa, Neftali; Urueña, Gloria


    Cattleya trianae is an endemic species from the tropical rainforest in the Colombian Andes. Its survival is currently threatened due to habitat loss and commercial overexploitation. This study evaluates ten substrates, some organic (pine bark, coconut fiber and wood shavings), some inert icopor (polystyrene foam), vegetable coal and their combinations, and the effects these have on morphometric and phenotypic traits in the hardening phase of 250 plants of C. trianae cultivated in vitro. Recorded data include percent survival, length of longest leaf, biomass (wet weight) and number of roots and leaves at the beginning and at the end of the experiment. After the hardening phase, the plants were taken to a greenhouse and later to the natural environment. Coconut fiber alone or mixed in equal parts with pine bark and coal was the most efficient substrate when percent survival (80+/-SE=0.3742), biomass, and leaf length were evaluated. Hardened plants displayed qualitative characteristics such as vigor, hardness and waxy texture, strength of green coloration in the leaves, and velamen formation. Under greenhouse conditions, plants grew better with filtered light, relative humidity bordering on 80 %, permanent aeration, misting with water, and an average temperature of 25+/-2 degrees C. Invigorated plants were firmly anchored on their host trees.

  19. On the transition toughness of two RA martensitic steels in the irradiation hardening regime: a mechanism-based evaluation

    Odette, G. R.; Rathbun, H. J.; Rensman, J. W.; van den Broek, F. P.


    An analysis of the transition fracture toughness and constitutive behavior of F82H and Eurofer97 reduced activation martensitic steels are presented in both unirradiated and irradiated conditions. The unirradiated toughness data for F82H show very steep temperature dependence and the Eurofer97 toughness data measured with 5 mm versus 10 mm thick specimens are systematically higher. Both of these observations indicate a loss of constraint. Constraint loss adjustments are applied using a three-dimensional finite element analysis based toughness scaling model. The adjusted F82H results can be represented by a master curve (MC) and the corresponding 5 and 10 mm adjusted data fall in the same scatter band. The 10 mm irradiated specimens, with generally lower toughness levels, suffer minimal constraint loss. The irradiation induced MC T0 shifts (Δ T0) are analyzed in terms of changes in constitutive properties. The Δ T0 are generally consistent with the observed irradiation hardening. However, the effects of irradiation on post-yield strain hardening behavior must be considered to obtain self-consistent hardening-shift relations.

  20. Softening and Hardening of a Micro-electro-mechanical systems (MEMS) Oscillator in a Nonlinear Regime

    Johnson, Sarah; Edmonds, Terrence

    Micro-electro-mechanical systems or MEMS are used in a variety of today's technology and can be modeled using equations for nonlinear damped harmonic oscillators. Mathematical expressions have been formulated to determine resonance frequency shifts as a result of hardening and softening effects in MEMS devices. In this work we experimentally test the previous theoretical analysis of MEMS resonance frequency shifts in the nonlinear regime. Devices were put under low pressure at room temperature and swept through a range of frequencies with varying AC and DC excitation voltages to detect shifts in the resonant frequency. The MEMS device studied in this work exhibits a dominating spring softening effect due to the device's physical make-up. The softening effect becomes very dominant as the AC excitation is increased and the frequency shift of the resonance peak becomes quite significant at these larger excitations. Hardening effects are heavily dependent on mechanical factors that make up the MEMS devices. But they are not present in these MEMS devices. I will present our results along with the theoretical analysis of the Duffing oscillator model. This work was supported by NSF grant DMR-1461019 (REU) and DMR-1205891 (YL).