WorldWideScience

Sample records for transformation induced ductility

  1. Plastic Strain Induced Damage Evolution and Martensitic Transformation in Ductile Materials at Cryogenic Temperatures

    CERN Document Server

    Garion, C

    2002-01-01

    The Fe-Cr-Ni stainless steels are well known for their ductile behaviour at cryogenic temperatures. This implies development and evolution of plastic strain fields in the stainless steel components subjected to thermo-mechanical loads at low temperatures. The evolution of plastic strain fields is usually associated with two phenomena: ductile damage and strain induced martensitic transformation. Ductile damage is described by the kinetic law of damage evolution. Here, the assumption of isotropic distribution of damage (microcracks and microvoids) in the Representative Volume Element (RVE) is made. Formation of the plastic strain induced martensite (irreversible process) leads to the presence of quasi-rigid inclusions of martensite in the austenitic matrix. The amount of martensite platelets in the RVE depends on the intensity of the plastic strain fields and on the temperature. The evolution of the volume fraction of martensite is governed by a kinetic law based on the accumulated plastic strain. Both of thes...

  2. Plastic strain induced damage evolution and martensitic transformation in ductile materials at cryogenic temperatures

    International Nuclear Information System (INIS)

    Garion, C.; Skoczen, B.T.

    2002-01-01

    The Fe-Cr-Ni stainless steels are well known for their ductile behavior at cryogenic temperatures. This implies development and evolution of plastic strain fields in the stainless steel components subjected to thermo-mechanical loads at low temperatures. The evolution of plastic strain fields is usually associated with two phenomena: ductile damage and strain induced martensitic transformation. Ductile damage is described by the kinetic law of damage evolution. Here, the assumption of isotropic distribution of damage (microcracks and microvoids) in the Representative Volume Element (RVE) is made. Formation of the plastic strain induced martensite (irreversible process) leads to the presence of quasi-rigid inclusions of martensite in the austenitic matrix. The amount of martensite platelets in the RVE depends on the intensity of the plastic strain fields and on the temperature. The evolution of the volume fraction of martensite is governed by a kinetic law based on the accumulated plastic strain. Both of these irreversible phenomena, associated with the dissipation of plastic power, are included into the constitutive model of stainless steels at cryogenic temperatures. The model is tested on the thin-walled corrugated shells (known as bellows expansion joints) used in the interconnections of the Large Hadron Collider, the new proton storage ring being constructed at present at CERN

  3. Combined model of strain-induced phase transformation and orthotropic damage in ductile materials at cryogenic temperatures

    CERN Document Server

    Garion, Cedric

    2003-01-01

    Ductile materials (like stainless steel or copper) show at cryogenic temperatures three principal phenomena: serrated yielding (discontinuous in terms of dsigma/depsilon), plastic strain-induced phase transformations and evolution of ductile damage. The present paper deals exclusively with the two latter cases. Thus, it is assumed that the plastic flow is perfectly smooth. Both in the case of damage evolution and for the gamma-alpha prime phase transformation, the principal mechanism is related to the formation of plastic strain fields. In the constitutive modeling of both phenomena, a crucial role is played by the accumulated plastic strain, expressed by the Odqvist parameter p. Following the general trends, both in the literature concerning the phase transformation and the ductile damage, it is assumed that the rate of transformation and the rate of damage are proportional to the accumulated plastic strain rate. The gamma-alpha prime phase transformation converts the initially homogenous material to a two-p...

  4. Interstitial atoms enable joint twinning and transformation induced plasticity in strong and ductile high-entropy alloys.

    Science.gov (United States)

    Li, Zhiming; Tasan, Cemal Cem; Springer, Hauke; Gault, Baptiste; Raabe, Dierk

    2017-01-12

    High-entropy alloys (HEAs) consisting of multiple principle elements provide an avenue for realizing exceptional mechanical, physical and chemical properties. We report a novel strategy for designing a new class of HEAs incorporating the additional interstitial element carbon. This results in joint activation of twinning- and transformation-induced plasticity (TWIP and TRIP) by tuning the matrix phase's instability in a metastable TRIP-assisted dual-phase HEA. Besides TWIP and TRIP, such alloys benefit from massive substitutional and interstitial solid solution strengthening as well as from the composite effect associated with its dual-phase structure. Nanosize particle formation and grain size reduction are also utilized. The new interstitial TWIP-TRIP-HEA thus unifies all metallic strengthening mechanisms in one material, leading to twice the tensile strength compared to a single-phase HEA with similar composition, yet, at identical ductility.

  5. Improved ductility of a transformation-induced-plasticity steel by nanoscale austenite lamellae

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Y.F., E-mail: shenyf@smm.neu.edu.cn [Key Laboratory for Anisotropy and Texture of Materials (MOE), School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Liu, Y.D. [Key Laboratory for Anisotropy and Texture of Materials (MOE), School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Sun, X. [Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352 (United States); Wang, Y.D.; Zuo, L. [Key Laboratory for Anisotropy and Texture of Materials (MOE), School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Misra, R.D.K. [Laboratory for Excellence in Advanced Steel Research, Center for Structural and Functional Materials, Institute for Materials Research and Innovation, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504 (United States)

    2013-10-20

    TRIP (transformation-induced-plasticity) steel with a chemical composition of 0.19C–0.30Si–1.76Mn–1.52Al (weight percentage, wt%) have been treated by intercritical annealing and austempering process. The microstructures of the obtained samples consist of the ferrite, the bainite and the retained austenite phase. The volume fractions of the bainite and the retained austenite gradually increase with increasing the temperature of the intercritical annealing. Consequently, significantly different mechanical properties have been observed. The sample annealed at 820 °C (for 120 s) and partitioned at 400 °C (for 300 s) has the best combination of ultimate tensile strength (UTS, ∼682 MPa) and elongation to failure (∼70%) with about 26% of bainitic ferrite plates and 17% retained austenite in its microstructure. The retained austenite has a lamella morphology with 100‒300 nm in thickness and 2‒5 µm in length. On the contrary, the sample annealed at the same temperature without the partitioning process yields much lower UTS and elongation to failure.

  6. Novel ferrite–austenite duplex lightweight steel with 77% ductility by transformation induced plasticity and twinning induced plasticity mechanisms

    International Nuclear Information System (INIS)

    Sohn, Seok Su; Choi, Kayoung; Kwak, Jai-Hyun; Kim, Nack J.; Lee, Sunghak

    2014-01-01

    The need for lightweight materials has been an important issue in automotive industries to reduce greenhouse gas emission and to improve fuel efficiency. In addition, automotive steels require an excellent combination of strength and ductility to sustain automotive structures and to achieve complex shapes, but the traditional approach to obtain a reduction in weight from down-gauged steels with high strength has many limitations. Here, we present a new ferrite–austenite duplex lightweight steel containing a low-density element, Al; this steel exhibits tensile elongation up to 77% as well as high tensile strength (734 MPa). The enhanced properties are attributed to the simultaneous formation of deformation-induced martensites and deformation twins and the additional plasticity due to deformation twinning in austenite grains having optimal mechanical stability. The present work gives a promise for automotive applications requiring excellent properties as well as reduced specific weight

  7. Investigation of phase transformations in ductile cast iron of differential scanning calorimetry

    International Nuclear Information System (INIS)

    Przeliorz, R; Piatkowski, J

    2011-01-01

    The effect of heating rate on phase transformations to austenite range in ductile cast iron of the EN-GJS-450-10 grade was investigated. For studies of phase transformations, the technique of differential scanning calorimetry (DSC) was used. Micro structure was examined by optical microscopy. The calorimetric examinations have proved that on heating three transformations occur in this grade of ductile iron, viz. magnetic transformation at the Curie temperature, pearlite→austenite transformation and ferrite→austenite transformation. An increase in the heating rate shifts the pearlite→austenite and ferrite→austenite transformations to higher temperature range. At the heating rate of 5 and 15 deg. C min -1 , local extrema have been observed to occur: for pearlite→austenite transformation at 784 deg. C and 795 deg. C, respectively, and for ferrite+ graphite →austenite transformation at 805 deg. C and 821 deg. C, respectively. The Curie temperature of magnetic transformation was extrapolated to a value of 740 deg. C. Each transformation is related with a specific thermal effect. The highest value of enthalpy is accompanying the ferrite→austenite transformation, the lowest occurs in the case of pearlite→austenite transformation.

  8. Application of Differential Scanning Calorimetry (DSC in study of phase transformations in ductile iron

    Directory of Open Access Journals (Sweden)

    R. Przeliorz

    2010-04-01

    Full Text Available The effect of heating rate on phase transformations to austenite range in ductile iron of the EN-GJS-450-10 grade was investigated. For studies of phase transformations, the technique of differential scanning calorimetry (DSC was used. Microstructure was examined by optical microscopy. The calorimetric examinations have proved that on heating three transformations occur in this grade of ductile iron, viz. magnetic transformation at the Curie temperature, pearlite→austenite transformation and ferrite→austenite transformation. An increase in the heating rate shifts the pearlite→austenite and ferrite→austenite transformations to higher temperature range. At the heating rate of 5 and 15°C/min, local extrema have been observed to occur: for pearlite→austenite transformation at 784°C and 795°C, respectively, and for ferrite→austenite transformation at 805°C and 821°C, respectively. The Curie temperature of magnetic transformation was extrapolated to a value of 740°C. Each transformation is related with a specific thermal effect. The highest value of enthalpy is accompanying the ferrite→austenite transformation, the lowest occurs in the case of pearlite→austenite transformation.

  9. Sample Size Induced Brittle-to-Ductile Transition of Single-Crystal Aluminum Nitride

    Science.gov (United States)

    2015-08-01

    ARL-RP-0528 ● AUG 2015 US Army Research Laboratory Sample Size Induced Brittle-to- Ductile Transition of Single-Crystal Aluminum...originator. ARL-RP-0528 ● AUG 2015 US Army Research Laboratory Sample Size Induced Brittle-to- Ductile Transition of Single-Crystal...Sample Size Induced Brittle-to- Ductile Transition of Single-Crystal Aluminum Nitride 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT

  10. The effect of pearlite on the hydrogen-induced ductility loss in ductile cast irons

    Science.gov (United States)

    Matsuo, T.

    2017-05-01

    Hydrogen energy systems, such as a hydrogen fuel cell vehicle and a hydrogen station, are rapidly developing to solve global environmental problems and resource problems. The available structural materials used for hydrogen equipments have been limited to only a few relatively expensive metallic materials that are tolerant for hydrogen embrittlement. Therefore, for the realization of a hydrogen society, it is important to expand the range of materials available for hydrogen equipment and thereby to enable the use of inexpensive common materials. Therefore, ductile cast iron was, in this study, focused as a structural material that could contribute to cost reduction of hydrogen equipment, because it is a low-cost material having good mechanical property comparable to carbon steels in addition to good castability and machinability. The strength and ductility of common ductile cast irons with a ferritic-pearlitic matrix can be controlled by the volume fraction of pearlitic phase. In the case of carbon steels, the susceptibility to hydrogen embrittlement increases with increase in the pearlite fraction. Toward the development of ferritic-pearlitic ductile cast iron with reasonable strength for hydrogen equipment, it is necessary to figure out the effect of pearlite on the hydrogen embrittlement of this cast iron. In this study, the tensile tests were conducted using hydrogen-precharged specimens of three kinds of ferritic-pearlitic ductile cast irons, JIS-FCD400, JIS-FCD450 and JIS-FCD700. Based on the results, the role of pearlite in characterizing the hydrogen embrittlement of ductile cast iron was discussed.

  11. Ductility of Nanostructured Bainite

    Directory of Open Access Journals (Sweden)

    Lucia Morales-Rivas

    2016-12-01

    Full Text Available Nanostructured bainite is a novel ultra-high-strength steel-concept under intensive current research, in which the optimization of its mechanical properties can only come from a clear understanding of the parameters that control its ductility. This work reviews first the nature of this composite-like material as a product of heat treatment conditions. Subsequently, the premises of ductility behavior are presented, taking as a reference related microstructures: conventional bainitic steels, and TRIP-aided steels. The ductility of nanostructured bainite is then discussed in terms of work-hardening and fracture mechanisms, leading to an analysis of the three-fold correlation between ductility, mechanically-induced martensitic transformation, and mechanical partitioning between the phases. Results suggest that a highly stable/hard retained austenite, with mechanical properties close to the matrix of bainitic ferrite, is advantageous in order to enhance ductility.

  12. The Influence of the Induced Ferrite and Precipitates of Ti-bearing Steel on the Ductility of Continuous Casting Slab

    Science.gov (United States)

    Qian, Guoyu; Cheng, Guoguang; Hou, Zibing

    2015-11-01

    In order to investigate the loss of the ductility of Ti-bearing ship plate steel under 1000 °C, where the ductility begins to reduce rapidly, so the hot ductility of Ti-bearing ship plate steel has been obtained using the Gleeble 1500 thermal-mechanical simulator and also the studies about the effect of grain boundary ferrite films and precipitates containing Ti on the ductility has been carried out. The result showed that the TiN particles precipitating at 950 °C with a larger size and smaller volume fraction cannot effectively suppress the occurrence of recrystallization and the ductility still retains at a high level, although R.A. value presents a certain degree of decline compared with 1000 °C. A large number of smaller Ti(C,N) particles precipitate at 900 °C and can induce the formation of a very small amount of fine grain boundary ferrite, which deteriorates the adhesion strength of the grain boundary, so the R.A. value rapidly reduces to less than 50%. When the temperature falls to close Ae3 (827 °C), the amount of the grain boundary ferrite films increase due to the ferrite phase transformation, but the ferrite film thickness becomes more uneven at the same time, which results in the increase of strain concentration and plays a leading role in causing the decrease of ductility, so the R.A. value has been kept less than 40% as the temperature cooling to 800 °C from 850 °C. When the temperature further decreases, the ductility starts to recover due to the increase of average ferrite film thickness to a greater degree which greatly reduces the strain concentration of the grain boundary.

  13. Experimental study of discontinuous plastic flow, phase transformation and micro-damage evolution in ductile materials at cryogenic temperatures

    CERN Document Server

    Marcinek, Dawid Jarosław; Sgobba, S

    2009-01-01

    The present Thesis deals with three low temperature phenomena occurring in ductile materials subjected to mechanical loads: serrated yielding, plastic strain induced γ-α’ phase transformation and evolution of micro-damage: - the Thesis explains the physical mechanisms governing each phenomenon at the micro and macroscopic levels; - the document describes in detail the advanced laboratory equipment needed for cryogenic experiments; - the results of tests carried out with unique precision and focused on serrated yielding and evolution of micro-damage (the observations were made with different strain rates and with the use of different materials) are presented; - validation of suitable kinetic laws and identification of parameters for tested materials is carried out.

  14. Unexpected pressure induced ductileness tuning in sulfur doped polycrystalline nickel metal

    Directory of Open Access Journals (Sweden)

    Cheng Guo

    2018-02-01

    Full Text Available The sulfur induced embrittlement of polycrystalline nickel (Ni metal has been a long-standing mystery. It is suggested that sulfur impurity makes ductile Ni metal brittle in many industry applications due to various mechanisms, such as impurity segregation and disorder-induced melting etc. Here we report an observation that the most ductile measurement occurs at a critical sulfur doping concentration, 14 at.% at pressure from 14 GPa up to 29 GPa through texture evolution analysis. The synchrotron-based high pressure texturing measurements using radial diamond anvil cell (rDAC X-ray diffraction (XRD techniques reveal that the activities of slip systems in the polycrystalline nickel metal are affected by sulfur impurities and external pressures, giving rise to the changes in the plastic deformation of the nickel metal. Dislocation dynamics (DD simulation on dislocation density and velocity further confirms the pressure induced ductilization changes in S doped Ni metal. This observation and simulation suggests that the ductilization of the doped polycrystalline nickel metal can be optimized by engineering the sulfur concentration under pressure, shedding a light on tuning the mechanical properties of this material for better high pressure applications.

  15. Unexpected pressure induced ductileness tuning in sulfur doped polycrystalline nickel metal

    Science.gov (United States)

    Guo, Cheng; Yang, Yan; Tan, Liuxi; Lei, Jialin; Guo, Shengmin; Chen, Bin; Yan, Jinyuan; Yang, Shizhong

    2018-02-01

    The sulfur induced embrittlement of polycrystalline nickel (Ni) metal has been a long-standing mystery. It is suggested that sulfur impurity makes ductile Ni metal brittle in many industry applications due to various mechanisms, such as impurity segregation and disorder-induced melting etc. Here we report an observation that the most ductile measurement occurs at a critical sulfur doping concentration, 14 at.% at pressure from 14 GPa up to 29 GPa through texture evolution analysis. The synchrotron-based high pressure texturing measurements using radial diamond anvil cell (rDAC) X-ray diffraction (XRD) techniques reveal that the activities of slip systems in the polycrystalline nickel metal are affected by sulfur impurities and external pressures, giving rise to the changes in the plastic deformation of the nickel metal. Dislocation dynamics (DD) simulation on dislocation density and velocity further confirms the pressure induced ductilization changes in S doped Ni metal. This observation and simulation suggests that the ductilization of the doped polycrystalline nickel metal can be optimized by engineering the sulfur concentration under pressure, shedding a light on tuning the mechanical properties of this material for better high pressure applications.

  16. Hydride-induced degradation of hoop ductility in textured zirconium-alloy tubes: A theoretical analysis

    International Nuclear Information System (INIS)

    Qin, W.; Szpunar, J.A.; Kozinski, J.

    2012-01-01

    Hydride-induced degradation of hoop ductility in Zr-alloy tubular components has been studied for many years because of its importance in the nuclear industry. In this paper the role of intergranular and intragranular δ-hydrides in the degradation of ductility of the textured Zr-alloy tubes is investigated. The correlation among hydride distribution, orientation and morphology in the tubes is formulated based on thermodynamic modeling, and then analyzed. The results show that the applied stress, the crystallographic texture of α-Zr matrix, the grain-boundary structure, and the morphology and size of Zr grains simultaneously govern the site preference and the orientation of hydrides. A criterion is proposed to determine the threshold stress of hydride reorientation. The hoop ductility of the hydrided Zr tubes is discussed using the concept of macroscopic fracture strain. It is shown that the intergranular hydrides may be more deleterious to ductility than the intragranular ones. This work defines a general framework for understanding the relation of the microstructure of hydride-forming materials to embrittlement.

  17. Ductile Glass of Polyrotaxane Toughened by Stretch-Induced Intramolecular Phase Separation.

    Science.gov (United States)

    Kato, Kazuaki; Nemoto, Kaito; Mayumi, Koichi; Yokoyama, Hideaki; Ito, Kohzo

    2017-09-27

    A new class of ductile glasses is created from a thermoplastic polyrotaxane. The hard glass, which has a Young's modulus of 1 GPa, shows crazing, necking, and strain hardening with a total elongation of 330%. Stress concentration is prevented through a unique stretch-induced intramolecular phase separation of the cyclic components and the exposed backbone. In situ synchrotron X-ray scattering studies indicate that the backbone polymer chains slip through the cyclic components in the regions where the stress is concentrated.

  18. Modelling of liquid sodium induced crack propagation in T91 martensitic steel: Competition with ductile fracture

    Energy Technology Data Exchange (ETDEWEB)

    Hemery, Samuel [Institut PPRIME, CNRS, Université de Poitiers, ISAE ENSMA, UPR 3346, Téléport 2, 1 Avenue Clément Ader, BP 40109, 86961 Futuroscope Chasseneuil Cedex (France); Berdin, Clotilde, E-mail: clotilde.berdin@u-psud.fr [Univ Paris-Sud, SP2M-ICMMO, CNRS UMR 8182, F-91405 Orsay Cedex (France); Auger, Thierry; Bourhi, Mariem [Ecole Centrale-Supelec, MSSMat CNRS UMR 8579, F-92295 Chatenay Malabry Cedex (France)

    2016-12-01

    Liquid metal embrittlement (LME) of T91 steel is numerically modeled by the finite element method to analyse experimental results in an axisymmetric notched geometry. The behavior of the material is identified from tensile tests then a crack with a constant crack velocity is introduced using the node release technique in order to simulate the brittle crack induced by LME. A good agreement between the simulated and the experimental macroscopic behavior is found: this suggests that the assumption of a constant crack velocity is correct. Mechanical fields during the embrittlement process are then extracted from the results of the finite element model. An analysis of the crack initiation and propagation stages: the ductile fracture probably breaks off the LME induced brittle fracture. - Highlights: • T91 martensitic steel is embrittled by liquid sodium depending on the loading rate at 573 K. • The mechanical behavior is modeled by a von Mises elastic-plastic law. • The LME induced crack propagates at a constant velocity. • The mechanical state at the crack tip does not explain a brittle crack arrest. • The occurrence of the ductile fracture breaks off the brittle fracture.

  19. Influence of radiation-induced segregation on ductility of a nickel-silicon alloy

    International Nuclear Information System (INIS)

    Packan, N.H.; Schroeder, H.; Kesternich, W.

    1986-01-01

    Flat tensile specimens 60 μm thick of Ni-8 at. % Si were irradiated to bulk damage levels of 0.1 to 0.3 dpa with either 7 MeV protons or 28 MeV alpha particles at 750 K. The alpha bombarded specimens incurred 750 at. ppM He per 0.1 dpa in the course of their damage-generating irradiation. Radiation-induced silicon segregation gave rise to Ni 3 Si layers at internal and external surfaces. Postirradiation tensile tests conducted either at 300 K or 720 K revealed fully ductile (chisel-edged) transgranular fracture profiles. There were no significant differences between the proton-bombarded specimens and the unbombarded controls, both exhibiting >25% total elongations, while the alpha-bombarded specimens showed ductile fractures with somewhat lower (17 to 18%) elongation values probably due to hardening caused by small helium bubbles. Certain specimens that were preimplanted with 250 to 1000 at. ppM He at 970 K to encourage intergranular failure and expose grain boundaries did fail intergranularly. It is concluded that radiation-induced silicon segregation does not cause intrinsic embrittlement

  20. Extra-electron induced covalent strengthening and generalization of intrinsic ductile-to-brittle criterion.

    Science.gov (United States)

    Niu, Haiyang; Chen, Xing-Qiu; Liu, Peitao; Xing, Weiwei; Cheng, Xiyue; Li, Dianzhong; Li, Yiyi

    2012-01-01

    Traditional strengthening ways, such as strain, precipitation, and solid-solution, come into effect by pinning the motion of dislocation. Here, through first-principles calculations we report on an extra-electron induced covalent strengthening mechanism, which alters chemical bonding upon the introduction of extra-valence electrons in the matrix of parent materials. It is responsible for the brittle and high-strength properties of Al(12)W-type compounds featured by the typical fivefold icosahedral cages, which are common for quasicrystals and bulk metallic glasses (BMGs). In combination with this mechanism, we generalize ductile-to-brittle criterion in a universal hyperbolic form by integrating the classical Pettifor's Cauchy pressure with Pugh's modulus ratio for a wide variety of materials with cubic lattices. This study provides compelling evidence to correlate Pugh's modulus ratio with hardness of materials and may have implication for understanding the intrinsic brittleness of quasicrystals and BMGs.

  1. Implications of radiation-induced reductions in ductility to the design of austenitic stainless steel structures

    International Nuclear Information System (INIS)

    Lucas, G.E.; Billone, M.; Pawel, J.E.; Hamilton, M.L.

    1995-01-01

    In the dose and temperature range anticipated for ITER, austenitic stainless steels exhibit significant hardening with a concomitant loss in work hardening and uniform elongation. However, significant post-necking ductility may still be retained. When uniform elongation (e u ) is well defined in terms of a plastic instability criterion, e u is found to sustain reasonably high values out to about 7 dpa in the temperature range 250-350 C, beyond which it decreases to about 0.3% for 316LN. This loss of ductility has significant implications to fracture toughness and the onset of new failure modes associated with hear instability. However, the retention of a significant reduction in area at failure following irradiation indicates a less severe degradation of low-cycle fatigue life in agreement with a limited amount of data obtained to date. Suggestions are made for incorporating these results into design criteria and future testing programs

  2. Dilatancy induced ductile-brittle transition of shear band in metallic glasses

    Science.gov (United States)

    Zeng, F.; Jiang, M. Q.; Dai, L. H.

    2018-04-01

    Dilatancy-generated structural disordering, an inherent feature of metallic glasses (MGs), has been widely accepted as the physical mechanism for the primary origin and structural evolution of shear banding, as well as the resultant shear failure. However, it remains a great challenge to determine, to what degree of dilatation, a shear banding will evolve into a runaway shear failure. In this work, using in situ acoustic emission monitoring, we probe the dilatancy evolution at the different stages of individual shear band in MGs that underwent severely plastic deformation by the controlled cutting technology. A scaling law is revealed that the dilatancy in a shear band is linearly related to its evolution degree. A transition from ductile-to-brittle shear bands is observed, where the formers dominate stable serrated flow, and the latter lead to a runaway instability (catastrophe failure) of serrated flow. To uncover the underlying mechanics, we develop a theoretical model of shear-band evolution dynamics taking into account an atomic-scale deformation process. Our theoretical results agree with the experimental observations, and demonstrate that the atomic-scale volume expansion arises from an intrinsic shear-band evolution dynamics. Importantly, the onset of the ductile-brittle transition of shear banding is controlled by a critical dilatation.

  3. Assessment of the radiation-induced loss of ductility in V-Cr-Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Rowcliffe, A.F.; Zinkle, S.J. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    Alloys based on the V-Cr-Ti system are attractive candidates for structural applications in fusion systems because of their low activation properties, high thermal stress factor (high thermal conductivity, moderate strength, and low coefficient of thermal expansion), and their good compatibility with liquid lithium. The U.S. program has defined a V-4Cr-4Ti (wt %) alloy as a leading candidate alloy based upon evidence from laboratory-scale (30 kg) heats covering the approximate composition range 0-8 wt % Ti and 5 to 15 wt % Cr. A review of the effects of neutron displacement damage, helium, and hydrogen generation on mechanical behavior, and of compatibility with lithium, water, and helium environments was presented at the ICFRM-5 conference at Clearwater in 1991. The results of subsequent optimization studies, focusing on the effects of fast reactor irradiation on tensile and impact properties of a range of alloys, were presented at the ICFRM-6 conference at Stresa in 1993. The primary conclusion of this work was that the V-4Cr-4Ti alloy composition possessed a near-optimal combination of physical and mechanical properties for fusion structural applications. Subsequently, a production-scale (500 kg) heat of V-4Cr-4Ti (Heat No. 832665) was procured from Teledyne Wah-Chang, together with several 15 kg heats of alloys with small variations in Cr and Ti. Further testing has been carried out on these alloys, including neutron irradiation experiments to study swelling and mechanical property changes. This paper discusses ductility measurements from some of these tests which are in disagreement with earlier work.

  4. Development of Nanostructured Austempered Ductile Cast Iron

    Science.gov (United States)

    Panneerselvam, Saranya

    Austempered Ductile Cast Iron is emerging as an important engineering materials in recent years because of its excellent combination of mechanical properties such as high strength with good ductility, good fatigue strength and fracture toughness together with excellent wear resistance. These combinations of properties are achieved by the microstructure consisting of acicular ferrite and high carbon austenite. Refining of the ausferritic microstructure will further enhance the mechanical properties of ADI and the presence of proeutectoid ferrite in the microstructure will considerably improve the ductility of the material. Thus, the focus of this investigation was to develop nanostructured austempered ductile cast iron (ADI) consisting of proeutectoid ferrite, bainitic ferrite and high carbon austenite and to determine its microstructure-property relationships. Compact tension and cylindrical tensile test samples were prepared as per ASTM standards, subjected to various heat treatments and the mechanical tests including the tensile tests, plane strain fracture toughness tests, hardness tests were performed as per ASTM standards. Microstructures were characterized by optical metallography, X-ray diffraction, SEM and TEM. Nanostructured ADI was achieved by a unique heat treatment consisting of austenitization at a high temperature and subsequent plastic deformation at the same austenitizing temperature followed by austempering. The investigation also examined the effect of cryogenic treatment, effect of intercritical austenitizing followed by single and two step austempering, effect of high temperature plastic deformation on the microstructure and mechanical properties of the low alloyed ductile cast iron. The mechanical and thermal stability of the austenite was also investigated. An analytical model has been developed to understand the crack growth process associated with the stress induced transformation of retained austenite to martensite.

  5. Deformation induced martensitic transformation in stainless steels

    International Nuclear Information System (INIS)

    Nagy, E.; Mertinger, V.; Tranta, F.; Solyom, J.

    2003-01-01

    Deformation induced martensitic transformation was investigated in metastable austenitic stainless steel. This steel can present a microstructure of austenite (γ), α' martensite and non magnetic ε martensite. Uni-axial tensile test was used for loading at different temperatures below room temperature (from -120 to 20 deg. C). During the deformation the transformation takes place at certain places in an anisotropic way and texture also develops. Quantitative phase analysis was done by X-ray diffraction (XRD) and magnetic methods while the texture was described by X-ray diffraction using a special inverse pole figure. The quantitative phase analysis has shown that the formation of α' and ε martensite from austenite is the function of deformation rate, and deformation temperature. The transformation of the textured austenite takes place in an anisotropic way and a well defined crystallographic relationship between the parent and α' martensite phase has been measured

  6. Mechanical joining of materials with limited ductility: Analysis of process-induced defects

    Science.gov (United States)

    Jäckel, M.; Coppieters, S.; Hofmann, M.; Vandermeiren, N.; Landgrebe, D.; Debruyne, D.; Wallmersberger, T.; Faes, K.

    2017-10-01

    The paper shows experimental and numerical analyses of the clinching process of 6xxx series aluminum sheets in T6 condition and the self-pierce riveting process of an aluminum die casting. In the experimental investigations the damage behavior of the materials when using different tool parameters is analyzed. The focus of the numerical investigations is the damage prediction by a comparison of different damage criteria. Moreover, strength-and fatigue tests were carried out to investigate the influence of the joining process-induced damages on the strength properties of the joints.

  7. Stress-induced phase transformation and room temperature aging in Ti-Nb-Fe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Cai, S.; Schaffer, J.E. [Fort Wayne Metals Research Products Corp, 9609 Ardmore Ave., Fort Wayne, IN 46809 (United States); Ren, Y. [Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439 (United States)

    2017-01-05

    Room temperature deformation behavior of Ti-17Nb-1Fe and Ti-17Nb-2Fe alloys was studied by synchrotron X-ray diffraction and tensile testing. It was found that, after proper heat treatment, both alloys were able to recover a deformation strain of above 3.5% due to the Stress-induced Martensite (SIM) phase transformation. Higher Fe content increased the beta phase stability and onset stress for SIM transformation. A strong {110}{sub β} texture was produced in Ti-17Nb-2Fe compared to the {210}{sub β} texture that was observed in Ti-17Nb-1Fe. Room temperature aging was observed in both alloys, where the formation of the omega phase increased the yield strength (also SIM onset stress), and decreased the ductility and strain recovery. Other metastable beta Ti alloys may show a similar aging response and this should draw the attention of materials design engineers.

  8. Microstructure design of low alloy transformation-induced plasticity assisted steels

    Science.gov (United States)

    Zhu, Ruixian

    The microstructure of low alloy Transformation Induced Plasticity (TRIP) assisted steels has been systematically varied through the combination of computational and experimental methodologies in order to enhance the mechanical performance and to fulfill the requirement of the next generation Advanced High Strength Steels (AHSS). The roles of microstructural parameters, such as phase constitutions, phase stability, and volume fractions on the strength-ductility combination have been revealed. Two model alloy compositions (i.e. Fe-1.5Mn-1.5Si-0.3C, and Fe-3Mn-1Si-0.3C in wt%, nominal composition) were studied. Multiphase microstructures including ferrite, bainite, retained austenite and martensite were obtained through conventional two step heat treatment (i.e. intercritical annealing-IA, and bainitic isothermal transformation-BIT). The effect of phase constitution on the mechanical properties was first characterized experimentally via systematically varying the volume fractions of these phases through computational thermodynamics. It was found that martensite was the main phase to deteriorate ductility, meanwhile the C/VA ratio (i.e. carbon content over the volume fraction of austenite) could be another indicator for the ductility of the multiphase microstructure. Following the microstructural characterization of the multiphase alloys, two microstructural design criteria (i.e. maximizing ferrite and austenite, suppressing athermal martensite) were proposed in order to optimize the corresponding mechanical performance. The volume fraction of ferrite was maximized during the IA with the help of computational thermodyanmics. On the other hand, it turned out theoretically that the martensite suppression could not be avoided on the low Mn contained alloy (i.e. Fe- 1.5Mn-1.5Si-0.3C). Nevertheless, the achieved combination of strength (~1300MPa true strength) and ductility (˜23% uniform elongation) on the low Mn alloy following the proposed design criteria fulfilled the

  9. Pressure Induced Phase Transformations in Ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Reimanis, Ivar [Colorado School of Mines, Golden, CO (United States); Cioabanu, Cristian [Colorado School of Mines, Golden, CO (United States)

    2017-10-15

    The study of materials with unusual properties offers new insight into structure-property relations as well as promise for the design of novel composites. In this spirit, the PIs seek to (1) understand fundamental mechanical phenomena in ceramics that exhibit pressure-induced phase transitions, negative coefficient of thermal expansion (CTE), and negative compressibility, and (2) explore the effect of these phenomena on the mechanical behavior of composites designed with such ceramics. The broad and long-term goal is to learn how to utilize these unusual behaviors to obtain desired mechanical responses. While the results are expected to be widely applicable to many ceramics, most of the present focus is on silicates, as they exhibit remarkable diversity in structure and properties. Eucryptite, a lithium aluminum silicate (LiAlSiO4), is specifically targeted because it exhibits a pressure-induced phase transition at a sufficiently low pressure to be accessible during conventional materials processing. Thus, composites with eucryptite may be designed to exhibit a novel type of transformation toughening. The PIs have performed a combination of activities that encompass synthesis and processing to control structures, atomistic modeling to predict and understand structures, and characterization to study mechanical behavior. Several materials behavior discoveries were made. It was discovered that small amounts of Zn (as small as 0.1 percent by mol) reverse the sign of the coefficient of thermal expansion of beta-eucryptite from negative to slightly positive. The presence of Zn also significantly mitigates microcracking that occurs during thermal cycling of eucryptite. It is hypothesized that Zn disrupts the Li ordering in beta-eucryptite, thereby altering the thermal expansion behavior. A nanoindentation technique developed to characterize incipient plasticity was applied to examine the initial stages of the pressure induced phase transformation from beta to

  10. Influence of plastic strain on deformation-induced martensitic transformations

    NARCIS (Netherlands)

    Perdahcioglu, Emin Semih; Geijselaers, Hubertus J.M.; Groen, M.

    2008-01-01

    The effects of plastic strain on deformation-induced martensitic transformations have been investigated experimentally. Austenitic metastable stainless steel samples were heated to a temperature at which the transformation is suppressed and were plastically strained to different amounts. The

  11. Effect of deformation induced nucleation and phase mixing, a two phase model for the ductile deformation of rocks.

    Science.gov (United States)

    Bevillard, Benoit; Richard, Guillaume; Raimbourg, Hugues

    2017-04-01

    Rocks are complex materials and particularly their rheological behavior under geological stresses remains a long-standing question in geodynamics. To test large scale lithosphere dynamics numerical modeling is the main tool but encounter substantial difficulties to account for this complexity. One major unknown is the origin and development of the localization of deformation. This localization is observed within a large range of scales and is commonly characterized by sharp grain size reduction. These considerations argues for a control of the microscopical scale over the largest ones through one predominant variable: the mean grain-size. However, the presence of second phase and broad grain-size distribution may also have a important impact on this phenomenon. To address this question, we built a model for ductile rocks deformation based on the two-phase damage theory of Bercovici & Ricard 2012. We aim to investigate the role of grain-size reduction but also phase mixing on strain localization. Instead of considering a Zener-pining effect on damage evolution, we propose to take into account the effect of the grain-boundary sliding (GBS)-induced nucleation mechanism which is better supported by experimental or natural observations (Precigout et al 2016). This continuum theory allows to represent a two mineral phases aggregate with explicit log-normal grain-size distribution as a reasonable approximation for polymineralic rocks. Quantifying microscopical variables using a statistical approach may allow for calibration at small (experimental) scale. The general set of evolutions equations remains up-scalable provided some conditions on the homogenization scale. Using the interface density as a measure of mixture quality, we assume unlike Bercovici & Ricard 2012 that it may depend for some part on grain-size . The grain-size independent part of it is being represented by a "contact fraction" variable, whose evolution may be constrained by the dominant deformation

  12. Electron-irradiation-induced phase transformation in alumina

    International Nuclear Information System (INIS)

    Chen, C.L.; Arakawa, K.; Lee, J.-G.; Mori, H.

    2010-01-01

    In this study, electron-irradiation-induced phase transformations between alumina polymorphs were investigated by high-resolution transmission electron microscopy. It was found that the electron-irradiation-induced α → κ' phase transformation occurred in the alumina under 100 keV electron irradiation. It is likely that the knock-on collision between incident electrons and Al 3+ cations is responsible for the occurrence of electron-irradiation-induced phase transformation from α-alumina to κ'-alumina.

  13. Thermomechanical treatment of austempered ductile iron

    Directory of Open Access Journals (Sweden)

    A. A. Nofal

    2007-11-01

    Full Text Available The production of lightweight ferrous castings with increased strength properties became unavoidable facing the serious challenge of lighter aluminum and magnesium castings. The relatively new ferrous casting alloy ADI offers promising strength prospects, and the thermo-mechanical treatment of ductile iron may suggest a new route for production of thin-wall products. This work aims at studying the influence of thermomechanical treatment, either by ausforming just after quenching and before the onset of austempering reaction or by cold rolling after austempering. In the first part of this work, ausforming of ADI up to 25% reduction in height during a rolling operation was found to add a mechanical processing component compared to the conventional ADI heat treatment, thus increasing the rate of ausferrite formation and leading to a much finer and more homogeneous ausferrite product. The kinetics of ausferrite formation was studied using both metallographic as well as XRD-techniques. The effect of ausforming on the strength was quite dramatic (up to 70% and 50% increase in the yield and ultimate strength respectively. A mechanism involving both a refined microstructural scale and an elevated dislocation density was suggested. Nickel is added to ADI to increase hardenability of thick section castings, while ausforming to higher degrees of deformation is necessary to alleviate the deleterious effect of alloy segregation on ductility. In the second part of this work, the influence of cold rolling (CR on the mechanical properties and structural characteristics of ADI was investigated. The variation in properties was related to the amount of retained austenite (γr and its mechanically induced ransformation. In the course of tensile deformation of ADI, transformation induced plasticity (TRIP takes place, indicated by the increase of the instantaneous value of strain-hardening exponent with tensile strain. The amount of retained austenite was found to

  14. Uncovering the local inelastic interactions during manufacture of ductile cast iron: How the substructure of the graphite particles can induce residual stress concentrations in the matrix

    Science.gov (United States)

    Andriollo, Tito; Hellström, Kristina; Sonne, Mads Rostgaard; Thorborg, Jesper; Tiedje, Niels; Hattel, Jesper

    2018-02-01

    Recent X-ray diffraction (XRD) measurements have revealed that plastic deformation and a residual elastic strain field can be present around the graphite particles in ductile cast iron after manufacturing, probably due to some local mismatch in thermal contraction. However, as only one component of the elastic strain tensor could be obtained from the XRD data, the shape and magnitude of the associated residual stress field have remained unknown. To compensate for this and to provide theoretical insight into this unexplored topic, a combined experimental-numerical approach is presented in this paper. First, a material equivalent to the ductile cast iron matrix is manufactured and subjected to dilatometric and high-temperature tensile tests. Subsequently, a two-scale hierarchical top-down model is devised, calibrated on the basis of the collected data and used to simulate the interaction between the graphite particles and the matrix during manufacturing of the industrial part considered in the XRD study. The model indicates that, besides the viscoplastic deformation of the matrix, the effect of the inelastic deformation of the graphite has to be considered to explain the magnitude of the XRD strain. Moreover, the model shows that the large elastic strain perturbations recorded with XRD close to the graphite-matrix interface are not artifacts due to e.g. sharp gradients in chemical composition, but correspond to residual stress concentrations induced by the conical sectors forming the internal structure of the graphite particles. In contrast to common belief, these results thus suggest that ductile cast iron parts cannot be considered, in general, as stress-free at the microstructural scale.

  15. Martensitic transformation induced by irradiation and deformation in stainless steels

    International Nuclear Information System (INIS)

    Maksimkin, O.P.

    1997-01-01

    In the present work the peculiarities of martensite γ → α , (γ → ε → α , ) transformation in the steels with a low stacking fault energy (12Cr18Ni10T, Cr15AG14) irradiated by neutrons, α-particles and electrons (pulse and stationary) and then deformed with the various strain rates in the temperature range - 20 - 1000 C are considered. It is established by the electron-microscope research that the phase γ → α ' transition in irradiated and deformed steels is observed on the definite stage of evolution of the dislocation structure (after the cell formation) and the martensite formation preferentially occurs on a stacking fault aggregation. The regularities of the irradiation by high energy particles effect on the formation parameters and martensite α , -phase accumulation kinetics ones and also their role in forming of the strength and ductile properties in steels are analysed. (A.A.D.)

  16. Stepwise transformation behavior of the strain-induced martensitic transformation in a metastable stainless steel

    International Nuclear Information System (INIS)

    Hedstroem, Peter; Lienert, Ulrich; Almer, Jon; Oden, Magnus

    2007-01-01

    In situ high-energy X-ray diffraction during tensile loading has been used to investigate the evolution of lattice strains and the accompanying strain-induced martensitic transformation in cold-rolled sheets of a metastable stainless steel. At high applied strains the transformation to α-martensite occurs in stepwise bursts. These stepwise transformation events are correlated with stepwise increased lattice strains and peak broadening in the austenite phase. The stepwise transformation arises from growth of α-martensite embryos by autocatalytic transformation

  17. Thermally induced phase transformation of pearl powder

    International Nuclear Information System (INIS)

    Zhang, Guoqing; Guo, Yili; Ao, Ju; Yang, Jing; Lv, Guanglie; Shih, Kaimin

    2013-01-01

    The polymorphic phase transformation of thermally treated pearl powder was investigated by X-ray diffraction and thermoanalytical techniques. The phase transformation was based on quantification of the calcite content at various temperatures using Rietveld refinement analysis. The results show that the phase transformation of pearl aragonite occurred within a temperature range of 360–410 °C, which is 50–100 °C lower than the range for non-biomineralized aragonite. These thermoanalytical results suggest that the phase transformation of pearl aragonite may occur immediately after the thermal decomposition of the organic matrix in the pearl powder. An important finding is that decomposition of the organic matrix may greatly facilitate such transformation by releasing additional space for an easier structural reconstruction during the phase transformation process. - Highlights: ► Providing a new method to describe the polymorphic transition of pearl powder ► The phase transition sketch was exhibited by XRD phase quantitative analysis. ► There are dozens of degrees in advance comparing to natural aragonite. ► The phase transition occurs following the thermal decomposition of organism

  18. Mechanisms of radiation-induced neoplastic cell transformation

    International Nuclear Information System (INIS)

    Yang, T.C.H.; Tobias, C.A.

    1984-04-01

    Studies with cultured mammalian cells demonstrated clearly that radiation can transform cells directly and can enhance the cell transformation by oncogenic DNA viruses. In general, high-LET heavy-ion radiation can be more effective than X and gamma rays in inducing neoplastic cell transformation. Various experimental results indicate that radiation-induced DNA damage, most likely double-strand breaks, is important for both the initiation of cell transformation and for the enhancement of viral transformation. Some of the transformation and enhancement lesions can be repaired properly in the cell, and the amount of irrepairable lesions produced by a given dose depends on the quality of radiation. An inhibition of repair processes with chemical agents can increase the transformation frequency of cells exposed to radiation and/or oncogenic viruses, suggesting that repair mechanisms may play an important role in the radiation transformation. The progression of radiation-transformed cells appears to be a long and complicated process that can be modulated by some nonmutagenic chemical agents, e.g., DMSO. Normal cells can inhibit the expression of transforming properties of tumorigenic cells through an as yet unknown mechanism. The progression and expression of transformation may involve some epigenetic changes in the irradiated cells. 38 references, 15 figures, 1 table

  19. Mechanisms of radiation-induced neoplastic cell transformation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, T.C.H.; Tobias, C.A.

    1984-04-01

    Studies with cultured mammalian cells demonstrated clearly that radiation can transform cells directly and can enhance the cell transformation by oncogenic DNA viruses. In general, high-LET heavy-ion radiation can be more effective than X and gamma rays in inducing neoplastic cell transformation. Various experimental results indicate that radiation-induced DNA damage, most likely double-strand breaks, is important for both the initiation of cell transformation and for the enhancement of viral transformation. Some of the transformation and enhancement lesions can be repaired properly in the cell, and the amount of irrepairable lesions produced by a given dose depends on the quality of radiation. An inhibition of repair processes with chemical agents can increase the transformation frequency of cells exposed to radiation and/or oncogenic viruses, suggesting that repair mechanisms may play an important role in the radiation transformation. The progression of radiation-transformed cells appears to be a long and complicated process that can be modulated by some nonmutagenic chemical agents, e.g., DMSO. Normal cells can inhibit the expression of transforming properties of tumorigenic cells through an as yet unknown mechanism. The progression and expression of transformation may involve some epigenetic changes in the irradiated cells. 38 references, 15 figures, 1 table.

  20. Protection of power transformers against geomagnetically induced currents

    Directory of Open Access Journals (Sweden)

    Gurevich Vladimir

    2011-01-01

    Full Text Available The article examines the problem of saturation and failure of power transformers under geomagnetically induced currents and currents of the E3 component of high-altitude nuclear explosions. It also describes a special protective relay reacting on DC component in the transformer neutral current.

  1. Neoplastic transformation induced by carbon ions.

    Science.gov (United States)

    Bettega, Daniela; Calzolari, Paola; Hessel, Petra; Stucchi, Claudio G; Weyrather, Wilma K

    2009-03-01

    The objective of this experiment was to compare the oncogenic potential of carbon ion beams and conventional photon beams for use in radiotherapy. The HeLa X human skin fibroblast cell line CGL1 was irradiated with carbon ions of three different energies (270, 100, and 11.4 MeV/u). Inactivation and transformation data were compared with those for 15 MeV photons. Inactivation and transformation frequencies for the 270 MeV/u carbon ions were similar to those for 15-MeV photons. The maximal relative biologic effectiveness (RBE(alpha)) values for 100MeV/u and 11.4 MeV/u carbon ions, respectively, were as follows: inactivation, 1.6 +/- 0.2 and 6.7 +/- 0.7; and transformation per surviving cell, 2.5 +/- 0.6 and 12 +/- 3. The curve for dose-transformation per cell at risk exhibited a maximum that was shifted toward lower doses at lower energies. Transformation induction per cell at risk for carbon ions in the entrance channel was comparable to that for photons, whereas for the lower energies, 100 MeV/u and 11 MeV/u, which are representative of the energies delivered to the tumor margins and volume, respectively, the probability of transformation in a single cell was greater than it was for photons. In addition, at isoeffective doses with respect to cell killing, the 11.4-MeV/u beam was more oncogenic than were photons.

  2. Dynamic strain-induced transformation: An atomic scale investigation

    International Nuclear Information System (INIS)

    Zhang, H.; Pradeep, K.G.; Mandal, S.; Ponge, D.; Springer, H.; Raabe, D.

    2015-01-01

    Phase transformations provide the most versatile access to the design of complex nanostructured alloys in terms of grain size, morphology, local chemical constitution etc. Here we study a special case of deformation induced phase transformation. More specifically, we investigate the atomistic mechanisms associated with dynamic strain-induced transformation (DSIT) in a dual-phased multicomponent iron-based alloy at high temperatures. DSIT phenomena and the associated secondary phase nucleation were observed at atomic scale using atom probe tomography. The obtained local chemical composition was used for simulating the nucleation process which revealed that DSIT, occurring during load exertion, proceeds by a diffusion-controlled nucleation process

  3. Thermally Induced Magnetite-Haematite Transformation

    International Nuclear Information System (INIS)

    Mazo-Zuluaga, J.; Barrero, C. A.; Diaz-Teran, J.; Jerez, A.

    2003-01-01

    The products of thermal treatments of pure and copper doped magnetites have been investigated using Moessbauer spectrometry, XRD and thermal analysis techniques. The samples were heated in air between RT and 800 o C at several heating rates. Samples treated at 520 o C during 12 and 24 hours consist only of well-crystallized haematite. On the other hand, magnetites treated at 350 o C consisted of mixtures of haematite, maghemite and magnetite, with relative amount of each phase depending on the presence of copper as well as on the heating time. Results show that the transformation of magnetite to haematite goes through the formation of maghemite, and that the presence of copper delays this transformation.

  4. Thermally Induced Magnetite-Haematite Transformation

    Energy Technology Data Exchange (ETDEWEB)

    Mazo-Zuluaga, J.; Barrero, C. A. [Universidad de Antioquia, Grupo de Estado Solido, Instituto de Fisica (Colombia); Diaz-Teran, J.; Jerez, A. [Universidad Nacional de Educacion a Distancia UNED, Po Senda del Rey 9, Departamento de Quimica Inorganica y Quimica Tecnica (Spain)

    2003-06-15

    The products of thermal treatments of pure and copper doped magnetites have been investigated using Moessbauer spectrometry, XRD and thermal analysis techniques. The samples were heated in air between RT and 800{sup o}C at several heating rates. Samples treated at 520{sup o}C during 12 and 24 hours consist only of well-crystallized haematite. On the other hand, magnetites treated at 350{sup o}C consisted of mixtures of haematite, maghemite and magnetite, with relative amount of each phase depending on the presence of copper as well as on the heating time. Results show that the transformation of magnetite to haematite goes through the formation of maghemite, and that the presence of copper delays this transformation.

  5. Plasticity induced phase transformation in molecular crystals

    OpenAIRE

    Koslowski, Marisol

    2014-01-01

    Solid state amorphization (SSA) can be achieved in crystalline materials including metal alloys, intermetallics, semiconductors, minerals and molecular crystals. Even though the mechanisms may differ in different materials, the crystalline to amorphous transformation occurs when the crystal reaches a metastable state in which its free energy is higher than that of the amorphous phase. SSA is observed in metal alloys because of interdiffusion of the crystalline elements during mechanical milli...

  6. Fracturing and Transformation Into Veins Beneath the Crustal Scale Brittle Ductile Transition - a Record of Co-seismic Loading and Post-seismic Relaxation

    Science.gov (United States)

    Nüchter, J. A.; Stöckhert, B.

    2005-12-01

    Metamorphic rocks approaching the crustal scale brittle-ductile transition (BDT) during exhumation are expected to become increasingly affected by short term stress fluctuations related to seismic activity in the overlying seismogenic layer (schizosphere), while still residing in a long-term viscous environment (plastosphere). The structural and microstructural record of quartz veins in low grade - high pressure metamorphic rocks from southern Evia, Greece, yields insight into the processes and conditions just beneath the long-term BDT at temperatures of about 300 to 350°C, which switches between brittle failure and viscous flow as a function of imposed stress or strain rate. The following features are characteristic: (1) The veins have formed from tensile fractures, with a typical length on the order of 10-1 to 101 m; (2) The veins are discordant with respect to foliation and all pre-existing structures, with a uniform orientation over more than 500 km2; (3) The veins show a low aspect ratio of about 10 to 100 and an irregular or characteristic flame shape, which requires distributed ductile deformation of the host rock; (4) Fabrics of the sealing vein quartz indicate that - at a time - the veins were wide open cavities; (5) The sealing quartz crystals reveal a broad spectrum of microstructural features indicative of crystal plastic deformation at high stress and temperatures of about 300 to 350°C. These features indicate that opening and sealing of the fractures commenced immediately after brittle failure, controlled by ductile deformation of the host rock. Vein-parallel shortening was generally less than about 2%. Crystals formed early during sealing were plastically deformed upon progressive deformation and opening of the vein. The structural and microstructural record is interpreted as follows: Brittle failure is proposed to be a consequence of short term co-seismic loading. Subsequent opening of the fracture and sealing to become a vein is interpreted to

  7. Radiation-induced transformations of cellulose ethers

    International Nuclear Information System (INIS)

    Nud'ga, L.A.; Petropavlovskii, G.S.; Plisko, E.A.; Isakova, O.V.; Ershov, B.G.

    1988-01-01

    The purpose of this investigation was to study the transformation which take place under the action of γ-radiation in a number of cellulose ethers containing both saturated (carboxymethyl, hydroxyethyl) and unsaturated (allyl, methacryloyl) groups. Irradiation was carried out on a 60 Co unit in air at 77 and 300 K; the dose rate was 37 and 50 kGy/h respectively. The EPR spectra of γ-irradiated hydroxyethyl- and allylhydroxyethylcelluloses are identical. Under the action of γ-radiation extensive changes took place in cellulose ethers which are exhibited in degradation or the formation of three-dimensional structures and are accompanied by a change in the functional composition. The efficiency in the formation of radicals and their localization are determined by the nature and number of substituents in the cellulose ethers

  8. Characterisation of Ductile Prepregs

    Science.gov (United States)

    Pinto, F.; White, A.; Meo, M.

    2013-04-01

    This study is focused on the analysis of micro-perforated prepregs created from standard, off the shelf prepregs modified by a particular laser process to enhance ductility of prepregs for better formability and drapability. Fibres are shortened through the use of laser cutting in a predetermined pattern intended to maintain alignment, and therefore mechanical properties, yet increase ductility at the working temperature. The increase in ductility allows the product to be more effectively optimised for specific forming techniques. Tensile tests were conducted on several specimens in order to understand the ductility enhancement offered by this process with different micro-perforation patterns over standard prepregs. Furthermore, the effects of forming temperature was also analysed to assess the applicability of this material to hot draping techniques and other heated processes.

  9. Transformation induced plasticity in maraging steel: an experimental study

    International Nuclear Information System (INIS)

    Nagayama, K.; Kitajima, Y.; Kigami, S.; Tanaka, K.

    2000-01-01

    The deformation behavior of a maraging TRIP (transformation induced plasticity) steel (MAVAL X12) is studied experimentally under a constant load. The existence of the back stress in the axial direction is directly proved by investigating the dilatation curves. Martensite-start lines are given under tensile, compressive and shear stresses. The evolution of TRIP strain and the maximum TRIP strain are determined. The alloy response during isothermal tensile test is explained in terms of influences both by the composite and transformation. (orig.)

  10. In-situ studies of stress- and magnetic-field-induced phase transformation in a polymer-bonded Ni-Co-Mn-In composite

    International Nuclear Information System (INIS)

    Liu, D.M.; Nie, Z.H.; Wang, G.; Wang, Y.D.; Brown, D.E.; Pearson, J.; Liaw, P.K.; Ren, Y.

    2010-01-01

    A polymer-bonded Ni 45 Co 5 Mn 36.6 In 13.4 ferromagnetic shape-memory composite was fabricated, having magnetic-field-driven shape recovery properties. The thermo-magnetization curves of the composite suggested that the magnetic-field-induced reverse martensitic transformation occurs in the composite. The effects of temperature, stress, and magnetic-field on the phase transformation properties were systematically investigated using an in-situ high-energy X-ray diffraction technique. A temperature-induced reversible martensitic phase transformation was confirmed within the composite, showing a broad phase transformation interval. Stress-induced highly textured martensite was observed in the composite during uniaxial compressive loading, with a residual strain after unloading. The origin of the textured martensite can be explained by the grain-orientation-dependent Bain distortion energy. A recovery strain of ∼1.76% along the compression direction was evidenced in the pre-strained composite with an applied magnetic-field of 5 T. This recovery was caused by the magnetic-field-induced reverse martensitic phase transformation. The phase transformation properties of the ferromagnetic shape-memory composite, different from its bulk alloys, can be well explained by the Clausius-Clapeyron relation. The large magnetic-field-induced strain, together with good ductility and low cost, make the polymer-bonded Ni-Co-Mn-In composites potential candidates for magnetic-field-driven actuators.

  11. Grain-orientation-dependent of γ–ε–α′ transformation and twinning in a super-high-strength, high ductility austenitic Mn-steel

    Energy Technology Data Exchange (ETDEWEB)

    Eskandari, M., E-mail: m.eskandari@scu.ac.ir [Department of Materials Science & Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz, Ahvaz (Iran, Islamic Republic of); Zarei-Hanzaki, A. [Hot Deformation & Thermo-mechanical Processing of High Performance Engineering Materials, School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Mohtadi-Bonab, M.A. [Department of Mechanical Engineering, University of Bonab, Velayat Highway (Iran, Islamic Republic of); Onuki, Y. [Frontier Research Center for Applied Atomic Sciences, Ibaraki University (Japan); Basu, R. [Department of Mechanical Engineering, ITM University, Gurgaon (India); Asghari, A. [Electrical and Computer Engineering Department, University of Texas at San Antonio, Texas (United States); Szpunar, J.A. [Advanced Materials for Clean Energy, Department of Mechanical Engineering, University of Saskatchewan (Canada)

    2016-09-30

    A newly developed, austenitic lightweight steel, containing a low-density element, Al, exhibits tensile elongation up to 50% as well as high ultimate-tensile stress (tensile fracture at 1800 MPa) without necking behavior. Electron backscatter diffraction analysis is carried out to investigate the orientation dependence of the martensitic transformation in tensile testing to 30% strain at 323 K (25 °C). A pronounced γ→ε→α′ transformation is observed in <111> and <110>∥TD (TD: tensile direction) γ-grains. The α′-transformation textures is analyzed. Large misorientation spreads is seen in the <100>∥TD γ-grains. Interestingly, twin-assisted martensitic transformation is detected in the <111>∥TD followed by the twin boundary directly moving to a γ/α′ phase boundary. These phenomena are related to a change of Schmid factor for different orientations of grains.

  12. A comprehensive review of metal-induced cellular transformation studies.

    Science.gov (United States)

    Chen, Qiao Yi; Costa, Max

    2017-09-15

    In vitro transformation assays not only serve practical purposes in screening for potential carcinogenic substances in food, drug, and cosmetic industries, but more importantly, they provide a means of understanding the critical biological processes behind in vivo cancer development. In resemblance to cancer cells in vivo, successfully transformed cells display loss of contact inhibition, gain of anchorage independent growth, resistant to proper cell cycle regulation such as apoptosis, faster proliferation rate, potential for cellular invasion, and ability to form tumors in experimental animals. Cells purposely transformed using metal exposures enable researchers to examine molecular changes, dissect various stages of tumor formation, and ultimately elucidate metal induced cancer mode of action. For practical purposes, this review specifically focuses on studies incorporating As-, Cd-, Cr-, and Ni-induced cell transformation. Through investigating and comparing an extensive list of studies using various methods of metal-induced transformation, this review serves to bridge an information gap and provide a guide for avoiding procedural discrepancies as well as maximizing experimental efficiency. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. In vitro cell transformation induced by synthetic amorphous silica nanoparticles.

    Science.gov (United States)

    Fontana, Caroline; Kirsch, Anaïs; Seidel, Carole; Marpeaux, Léa; Darne, Christian; Gaté, Laurent; Remy, Aurélie; Guichard, Yves

    2017-11-01

    Synthetic amorphous silica nanoparticles (SAS) are among the most widely produced and used nanomaterials, but little is known about their carcinogenic potential. This study aims to evaluate the ability of four different SAS, two precipitated, NM-200 and NM-201, and two pyrogenic, NM-202 and NM-203, to induce the transformation process. For this, we used the recently developed in vitro Bhas 42 cell transformation assay (CTA). The genome of the transgenic Bhas 42 cells contains several copies of the v-Ha-ras gene, making them particularly sensitive to tumor-promoter agents. The Bhas 42 CTA, which includes an initiation assay and a promotion assay, was validated in our laboratory using known soluble carcinogenic substances. Its suitability for particle-type substances was verified by using quartz Min-U-Sil 5 (Min-U-Sil) and diatomaceous earth (DE) microparticles. As expected given their known transforming properties, Min-U-Sil responded positively in the Bhas 42 CTA and DE responded negatively. Transformation assays were performed with SAS at concentrations ranging from 2μg/cm 2 to 80μg/cm 2 . Results showed that all SAS have the capacity to induce transformed foci, interestingly only in the promotion assay, suggesting a mode of action similar to tumor-promoter substances. NM-203 exhibited transforming activity at a lower concentration than the other SAS. In conclusion, this study showed for the first time the transforming potential of different SAS, which act as tumor-promoter substances in the Bhas 42 model of cell transformation. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Rb-Sr dating of strain-induced mineral growth in two ductile shear zones in the western gneiss region of Nord-Troendelag, Central Norway

    International Nuclear Information System (INIS)

    Piasecki, M.A.; Cliff, R.A.

    1988-01-01

    In the Bjugn district of the northern part of the Western Gneiss Region, Nord-Troendelag, a basement gneiss-cover nappe boundary is marked by a thick zone of ductile shearing. In this zone a layer-parallel mylonitic fabric with related new mineral growth overprints and retrogresses a previous fabric associated with a granulite facies mineral assemblage. Related minor shear belts contain abundant new minerals and vein systems, including pegmatites, believed to represent strain-induced products formed at the time of the shearing movements. Central parts of two large muscovite books from such a pegmatite yielded Rb-Sr, Early to Middle Devonian ages of 389±6 Ma and 386±6 Ma, interpreted as indicating the approximate time of pegmatite formation and of the shearing. Small, matrix-size muscovite and biotite grains from the host mylonite gave ages of 378±6 Ma and 365±5 Ma, respectively, supposed to relate to post-shearing uplift and cooling

  15. Hot ductility of medium carbon steel with vanadium

    International Nuclear Information System (INIS)

    Lee, Chang-Hoon; Park, Jun-Young; Chung, JunHo; Park, Dae-Bum; Jang, Jin-Young; Huh, Sungyul; Ju Kim, Sung; Kang, Jun-Yun; Moon, Joonoh; Lee, Tae-Ho

    2016-01-01

    Hot ductility of medium carbon steel containing 0.52 wt% of carbon and 0.11 wt% of vanadium was investigated using a hot tensile test performed up to fracture. The hot ductility was evaluated by measuring the reduction of area of the fractured specimens, which were strained at a variety of test temperatures in a range of 600–1100 °C at a strain rate of 2×10"−"3/s. The hot ductility was excellent in a temperature range of 950–1100 °C, followed by a decrease of the hot ductility below 950 °C. The hot ductility continued to drop as the temperature was lowered to 600 °C. The loss of hot ductility in a temperature range of 800–950 °C, which is above the Ae_3 temperature, was due to V(C,N) precipitation at austenite grain boundaries. The further decline of hot ductility between 700 °C and 750 °C resulted from the transformation of ferrite films decorating austenite grain boundaries. The hot ductility continued to decrease at 650 °C or less, owing to ferrite films and the pearlite matrix, which is harder than ferrite. The pearlite was transformed from austenite due to relatively high carbon content.

  16. Radiation-induced rhabdomyosarcomatous transformation of a recurrent meningeal haemangiopericytoma

    International Nuclear Information System (INIS)

    Ka Kit Leung, G.; Chun Kit Lee, W.; Nicholls, J.M.

    2007-01-01

    A 53-year-old woman presented in 1979 with a posterior fossa meningeal haemangiopericytoma (HPC) for which she underwent surgical resection and post-operative radiotherapy. Repeated tumor recurrences occurred 18 years afterwards which were treated with resections and stereotactic radiotherapy. Surgery for tumor recurrence in 2005 revealed features of rhabdomyosarcomatous transformation. To our knowledge, this is the first reported case of rhabdomyosarcomatous transformation within a HPC which was likely to be radiation-induced, and was associated with relentless disease progression more than 20 years after the initial presentation. (author)

  17. Microstructure-based constitutive modeling of TRIP steel: Prediction of ductility and failure modes under different loading conditions

    International Nuclear Information System (INIS)

    Choi, K.S.; Liu, W.N.; Sun, X.; Khaleel, M.A.

    2009-01-01

    We study the ultimate ductility and failure modes of a commercial transformation-induced plasticity (TRIP) 800 steel under different loading conditions with an advanced microstructure-based finite-element analysis. The representative volume element (RVE) for the TRIP 800 under examination is developed based on an actual microstructure obtained from scanning electron microscopy. The ductile failure of the TRIP 800 under different loading conditions is predicted in the form of plastic strain localization without any prescribed failure criteria for the individual phases. This indicates that the microstructure-level inhomogeneity of the various constituent phases can be the key factor influencing the final ductility of the TRIP 800 steel under different loading conditions. Comparisons of the computational results with experimental measurements suggest that the microstructure-based modeling approach accurately captures the overall macroscopic behavior of the TRIP 800 steel under different loading and boundary conditions.

  18. Why ductile fracture mechanics

    International Nuclear Information System (INIS)

    Ritchie, R.O.

    1983-01-01

    Until recently, the engineering application of fracture mechanics has been specific to a description of macroscopic fracture behavior in components and structural parts which remain nominally elastic under loading. While this approach, termed linear elastic fracture mechanics, has been found to be invaluable for the continuum analysis of crack growth in brittle and high strength materials, it is clearly inappropriate for characterizing failure in lower strength ductile alloys where extensive inelastic deformation precedes and accompanies crack initiation and subsequent propagation. Accordingly, much effort has been devoted in recent years toward the development of nonlinear or ductile fracture mechanics methodology to characterize fracture behavior under elastic/plastic conditions; an effort which has been principally motivated by problems in nuclear industry. In this paper, the concepts of ductile (elastic/plastic) fracture mechanics are introduced and applied to the problem of both stationary and nonstationary cracks. Specifically, the limitations inherent in this approach are defined, together with a description of the microstructural considerations and applications relevant to the failure of ductile materials by fracture, fatigue, and creep

  19. Ductile transplutonium metal alloys

    Science.gov (United States)

    Conner, William V.

    1983-01-01

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as sources of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  20. An Electron Microscope Study of the Thermal Neutron Induced Loss in High Temperature Tensile Ductility of Nb Stabilized Austenitic Steels

    Energy Technology Data Exchange (ETDEWEB)

    Roy, R B

    1965-04-15

    Irradiated {approx}3 x 10{sup 19} n/cm{sup 2} (thermal), <3 x 10{sup 18} n/cm{sup 2} (> 1 MeV) at 40 deg C and the corresponding unirradiated control tensile specimens of a 20 % Cr, 25 % Ni, Nb stabilized steel tested at 650 deg C, 750 deg C and 800 deg C have been examined by transmission electron microscopy. The results indicate that the irradiation induced embrittlement of the tensile specimens at elevated temperatures is preceded by the formation of fine precipitates within the grains. These precipitates may restrict the deformation within the grains such that the stresses are concentrated at the grain boundaries thereby leading to premature failure. It is suggested that the main effect of the irradiation is to promote conditions necessary for the formation of these precipitates, namely, super saturation and fresh nucleation sites within the matrix through the energetic emission of He and Li atoms from boron as an impurity.

  1. An Electron Microscope Study of the Thermal Neutron Induced Loss in High Temperature Tensile Ductility of Nb Stabilized Austenitic Steels

    International Nuclear Information System (INIS)

    Roy, R.B.

    1965-04-01

    Irradiated ∼3 x 10 19 n/cm 2 (thermal), 18 n/cm 2 (> 1 MeV) at 40 deg C and the corresponding unirradiated control tensile specimens of a 20 % Cr, 25 % Ni, Nb stabilized steel tested at 650 deg C, 750 deg C and 800 deg C have been examined by transmission electron microscopy. The results indicate that the irradiation induced embrittlement of the tensile specimens at elevated temperatures is preceded by the formation of fine precipitates within the grains. These precipitates may restrict the deformation within the grains such that the stresses are concentrated at the grain boundaries thereby leading to premature failure. It is suggested that the main effect of the irradiation is to promote conditions necessary for the formation of these precipitates, namely, super saturation and fresh nucleation sites within the matrix through the energetic emission of He and Li atoms from boron as an impurity

  2. Characteristics of radiation-induced neoplastic transformation in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Little, J.B.

    1986-01-01

    Data are presented to support the hypothesis that the initial step in the morphologic transformation of irradiated rodent (BALB/3T3) cells is a frequent cellular event involving a large fraction of the irradiated population. This process appears to involve DNA damage, but not to represent a targeted mutation in specific structural gene(s). Morphologic transformation and immortalization appear to be distinct steps in the overall process of transformation. In contradistinction to rodent cells, immortalization is a very rare event in human diploid cells which is induced at extremely low frequencies. The hypothesis is presented that immortality develops among clones of cells bearing stable chromosomal rearrangements which emerge during the proliferation of a population of radiation damaged cells.

  3. Pressure-induced transformations in computer simulations of glassy water

    Science.gov (United States)

    Chiu, Janet; Starr, Francis W.; Giovambattista, Nicolas

    2013-11-01

    Glassy water occurs in at least two broad categories: low-density amorphous (LDA) and high-density amorphous (HDA) solid water. We perform out-of-equilibrium molecular dynamics simulations to study the transformations of glassy water using the ST2 model. Specifically, we study the known (i) compression-induced LDA-to-HDA, (ii) decompression-induced HDA-to-LDA, and (iii) compression-induced hexagonal ice-to-HDA transformations. We study each transformation for a broad range of compression/decompression temperatures, enabling us to construct a "P-T phase diagram" for glassy water. The resulting phase diagram shows the same qualitative features reported from experiments. While many simulations have probed the liquid-state phase behavior, comparatively little work has examined the transitions of glassy water. We examine how the glass transformations relate to the (first-order) liquid-liquid phase transition previously reported for this model. Specifically, our results support the hypothesis that the liquid-liquid spinodal lines, between a low-density and high-density liquid, are extensions of the LDA-HDA transformation lines in the limit of slow compression. Extending decompression runs to negative pressures, we locate the sublimation lines for both LDA and hyperquenched glassy water (HGW), and find that HGW is relatively more stable to the vapor. Additionally, we observe spontaneous crystallization of HDA at high pressure to ice VII. Experiments have also seen crystallization of HDA, but to ice XII. Finally, we contrast the structure of LDA and HDA for the ST2 model with experiments. We find that while the radial distribution functions (RDFs) of LDA are similar to those observed in experiments, considerable differences exist between the HDA RDFs of ST2 water and experiment. The differences in HDA structure, as well as the formation of ice VII (a tetrahedral crystal), are a consequence of ST2 overemphasizing the tetrahedral character of water.

  4. Laser induced structural transformation in chalcogenide based superlattices

    International Nuclear Information System (INIS)

    Zallo, Eugenio; Wang, Ruining; Bragaglia, Valeria; Calarco, Raffaella

    2016-01-01

    Superlattices made of alternating layers of nominal GeTe and Sb 2 Te 3 have been studied by micro-Raman spectroscopy. A structural irreversible transformation into ordered GeSbTe alloy is induced by high power laser light exposure. The intensity ratio of anti-Stokes and Stokes scattering under laser illumination gives a maximum average temperature in the sample of 177 °C. The latter is lower than the growth temperature and of 400 °C necessary by annealing to transform the structure in a GeSbTe alloy. The absence of this configuration after in situ annealing even up to 300 °C evidences an electronic excitation induced-transition which brings the system into a different and stable crystalline state.

  5. Laser induced structural transformation in chalcogenide based superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Zallo, Eugenio, E-mail: zallo@pdi-berlin.de; Wang, Ruining; Bragaglia, Valeria; Calarco, Raffaella [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

    2016-05-30

    Superlattices made of alternating layers of nominal GeTe and Sb{sub 2}Te{sub 3} have been studied by micro-Raman spectroscopy. A structural irreversible transformation into ordered GeSbTe alloy is induced by high power laser light exposure. The intensity ratio of anti-Stokes and Stokes scattering under laser illumination gives a maximum average temperature in the sample of 177 °C. The latter is lower than the growth temperature and of 400 °C necessary by annealing to transform the structure in a GeSbTe alloy. The absence of this configuration after in situ annealing even up to 300 °C evidences an electronic excitation induced-transition which brings the system into a different and stable crystalline state.

  6. Complexity estimates based on integral transforms induced by computational units

    Czech Academy of Sciences Publication Activity Database

    Kůrková, Věra

    2012-01-01

    Roč. 33, September (2012), s. 160-167 ISSN 0893-6080 R&D Projects: GA ČR GAP202/11/1368 Institutional research plan: CEZ:AV0Z10300504 Institutional support: RVO:67985807 Keywords : neural networks * estimates of model complexity * approximation from a dictionary * integral transforms * norms induced by computational units Subject RIV: IN - Informatics, Computer Science Impact factor: 1.927, year: 2012

  7. Kinetic of martensitic transformations induced by hydrogen in the austenite

    International Nuclear Information System (INIS)

    Oliveira, Sergio P. de; Saavedra, A.; Miranda, P.E.V. de

    1986-01-01

    The X-ray diffractometry technique was used, with an automatic data acquisition system to determine the kinetics of hydrogen induced martensitic phase transformations in an AISI 304 austenitic stainless steel type, used in nuclear power plants. Hydrogenation was performed cathodically in a 1N sulfuric acid solution, containing 100 mg/l of arsenic trioxide, at 50 0 C, during 2 hours and with a current density of 200 A/m 2 . It was found that the microstructure of the steel plays a role on the generation of hydrogen induced martensitic phases and surface micro cracks. Both kinetics were slower on a pre-cold rolled steel. (Author) [pt

  8. A macroscopic model to simulate the mechanically induced martensitic transformation in metastable austenitic stainless steels

    NARCIS (Netherlands)

    Perdahcioglu, Emin Semih; Geijselaers, Hubertus J.M.

    2012-01-01

    Mechanically induced martensitic transformation and the associated transformation plasticity phenomena in austenitic stainless steels are studied. The mechanisms responsible for the transformation are investigated and put into perspective based on experimental evidence. The stress and strain

  9. Ultrahigh Ductility, High-Carbon Martensitic Steel

    Science.gov (United States)

    Qin, Shengwei; Liu, Yu; Hao, Qingguo; Zuo, Xunwei; Rong, Yonghua; Chen, Nailu

    2016-10-01

    Based on the proposed design idea of the anti-transformation-induced plasticity effect, both the additions of the Nb element and pretreatment of the normalization process as a novel quenching-partitioning-tempering (Q-P-T) were designed for Fe-0.63C-1.52Mn-1.49Si-0.62Cr-0.036Nb hot-rolled steel. This high-carbon Q-P-T martensitic steel exhibits a tensile strength of 1890 MPa and elongation of 29 pct accompanied by the excellent product of tensile and elongation of 55 GPa pct. The origin of ultrahigh ductility for high-carbon Q-P-T martensitic steel is revealed from two aspects: one is the softening of martensitic matrix due to both the depletion of carbon in the matensitic matrix during the Q-P-T process by partitioning of carbon from supersaturated martensite to retained austenite and the reduction of the dislocation density in a martensitic matrix by dislocation absorption by retained austenite effect during deformation, which significantly enhances the deformation ability of martensitic matrix; another is the high mechanical stability of considerable carbon-enriched retained austenite, which effectively reduces the formation of brittle twin-type martensite. This work verifies the correctness of the design idea of the anti-TRIP effect and makes the third-generation advanced high-strength steels extend to the field of high-carbon steels from low- and medium-carbon steels.

  10. The Mechanism of High Ductility for Novel High-Carbon Quenching-Partitioning-Tempering Martensitic Steel

    Science.gov (United States)

    Qin, Shengwei; Liu, Yu; Hao, Qingguo; Wang, Ying; Chen, Nailu; Zuo, Xunwei; Rong, Yonghua

    2015-09-01

    In this article, a novel quenching-partitioning-tempering (Q-P-T) process was applied to treat Fe-0.6C-1.5Mn-1.5Si-0.6Cr-0.05Nb hot-rolled high-carbon steel and the microstructures including retained austenite fraction and the average dislocation densities in both martensite and retained austenite were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, respectively. The Q-P-T steel exhibits high strength (1950 MPa) and elongation (12.4 pct). Comparing with the steel treated by traditional quenching and tempering (Q&T) process, the mechanism of high ductility for high-carbon Q-P-T steel is revealed as follows. Much more retained austenite existing in Q-P-T steel than in Q&T one remarkably enhances the ductility by the following two effects: the dislocation absorption by retained austenite effect and the transformation-induced plasticity effect. Besides, lower dislocation density in martensite matrix produced by Q-P-T process plays an important role in the improvement of ductility. However, some thin plates of twin-type martensite embedded in dislocation-type martensite matrix in high-carbon Q-P-T steel affect the further improvement of ductility.

  11. Microstructure Evolution and Mechanical Behavior of a Hot-Rolled High-Manganese Dual-Phase Transformation-Induced Plasticity/Twinning-Induced Plasticity Steel

    Science.gov (United States)

    Fu, Liming; Shan, Mokun; Zhang, Daoda; Wang, Huanrong; Wang, Wei; Shan, Aidang

    2017-05-01

    The microstructures and deformation behavior were studied in a high-temperature annealed high-manganese dual-phase (28 vol pct δ-ferrite and 72 vol pct γ-austenite) transformation-induced plasticity/twinning-induced plasticity (TRIP/TWIP) steel. The results showed that the steel exhibits a special Lüders-like yielding phenomenon at room temperature (RT) and 348 K (75 °C), while it shows continuous yielding at 423 K, 573 K and 673 K (150 °C, 300 °C and 400 °C) deformation. A significant TRIP effect takes place during Lüders-like deformation at RT and 348 K (75 °C) temperatures. Semiquantitative analysis of the TRIP effect on the Lüders-like yield phenomenon proves that a softening effect of the strain energy consumption of strain-induced transformation is mainly responsible for this Lüders-like phenomenon. The TWIP mechanism dominates the 423 K (150 °C) deformation process, while the dislocation glide controls the plasticity at 573 K (300 °C) deformation. The delta-ferrite, as a hard phase in annealed dual-phase steel, greatly affects the mechanical stability of austenite due to the heterogeneous strain distribution between the two phases during deformation. A delta-ferrite-aided TRIP effect, i.e., martensite transformation induced by localized strain concentration of the hard delta-ferrite, is proposed to explain this kind of Lüders-like phenomenon. Moreover, the tensile curve at RT exhibits an upward curved behavior in the middle deformation stage, which is principally attributed to the deformation twinning of austenite retained after Lüders-like deformation. The combination of the TRIP effect during Lüders-like deformation and the subsequent TWIP effect greatly enhances the ductility in this annealed high-manganese dual-phase TRIP/TWIP steel.

  12. Micromechanics of transformation-induced plasticity and variant coalescence

    International Nuclear Information System (INIS)

    Marketz, F.; Fischer, F.D.; University for Mining and Metallurgy, Leoben; Tanaka, K.

    1996-01-01

    Quantitative micromechanics descriptions of both transformation-induced plasticity (TRIP) associated with the martensitic transformation in an Fe-Ni alloy and of variant coalescence in a Cu-Al-Ni shape memory alloy are presented. The macroscopic deformation behavior of a polycrystalline aggregate as a result of the rearrangements within the crystallites is modelled with the help of a finite element based periodic microfield approach. In the case of TRIP the parent→martensite transformation is described by microscale thermodynamic and kinetic equations taking into account internal stress states. The simulation of a classical experiment on TRIP allows to quantify the Magee-effect and the Greenwood-Johnson effect. Furthermore, the development of the martensitic microstructure is studied with respect to the stress-assisted transformation of preferred variants. In the case of variant coalescence the strain energy due to internal stress states has an important influence on the mechanical behavior. Formulating the reorientation process on the size scale of self-accommodating plate groups in terms of the mobility of the boundaries between martensitic variants the macroscopic behavior in uniaxial tension is predicted by an incremental modelling procedure. Furthermore, influence of energy dissipation on the overall behavior is quantified. (orig.)

  13. Depleted uranium induces neoplastic transformation in human lung epithelial cells.

    Science.gov (United States)

    Xie, Hong; LaCerte, Carolyne; Thompson, W Douglas; Wise, John Pierce

    2010-02-15

    Depleted uranium (DU) is commonly used in military armor and munitions, and thus, exposure of soldiers and noncombatants is frequent and widespread. Previous studies have shown that DU has both chemical and radiological toxicity and that the primary route of exposure of DU to humans is through inhalation and ingestion. However, there is limited research information on the potential carcinogenicity of DU in human bronchial cells. Accordingly, we determined the neoplastic transforming ability of particulate DU to human bronchial epithelial cells (BEP2D). We observed the loss of contact inhibition and anchorage independent growth in cells exposed to DU after 24 h. We also characterized these DU-induced transformed cell lines and found that 40% of the cell lines exhibit alterations in plating efficiency and no significant changes in the cytotoxic response to DU. Cytogenetic analyses showed that 53% of the DU-transformed cell lines possess a hypodiploid phenotype. These data indicate that human bronchial cells are transformed by DU and exhibit significant chromosome instability consistent with a neoplastic phenotype.

  14. The color-flavor transformation of induced QCD

    International Nuclear Information System (INIS)

    Shnir, Ya.

    2002-09-01

    The color-flavor transformation is applied to the U(N c ) lattice model, in which the gauge theory is induced by the chiral scalar field associated with an elementary plaquette. The flavor degrees of freedom are related with the number of generations of the auxiliary field, and flavor components of each generation are associated with all the plaquettes having a lattice site in common. The property of the dual color-flavor transformed theory, which is expressed in terms of the gauge singlets, are analyzed in d=2 and d=3 dimensions. The saddle point solution of the model in the large-N c limit is discussed. The correlations between the plaquettes, which are described by the dual theory, allows to define the dual lattice. In d=3 dimensions it is made of tetradecahedra which correspond to the cubes of the original lattice. The continuum limit of d=2 effective theory is discussed. (author)

  15. The color-flavor transformation of induced QCD

    CERN Document Server

    Shnir, Ya M

    2002-01-01

    The color-flavor transformation is applied to the $U(N_c)$ lattice model, in which the gauge theory is induced by the chiral scalar field associated with an elementary plaquette. The flavor degrees of freedom are related with the number of generations of the auxiliary field, and flavor components of each generation are associated with all the plaquettes having a lattice site in common. The property of the dual color-flavor transformed theory, which is expressed in terms of the gauge singlets, are analyzed in $d=2$ and $d=3$ dimensions. The saddle point solution of the model in the large-$N_c$ limit is discussed. The correlations between the plaquettes, which are described by the dual theory, allows to define the dual lattice. In $d=3$ dimensions it is made of tetradecahedra which correspond to the cubes of the original lattice. The continuum limit of $d=2$ effective theory is discussed.

  16. Texture developed during deformation of Transformation Induced Plasticity (TRIP) steels

    International Nuclear Information System (INIS)

    Bhargava, M; Asim, T; Sushil, M; Shanta, C

    2015-01-01

    Automotive industry is currently focusing on using advanced high strength steels (AHSS) due to its high strength and formability for closure applications. Transformation Induced Plasticity (TRIP) steel is promising material for this application among other AHSS. The present work is focused on the microstructure development during deformation of TRIP steel sheets. To mimic complex strain path condition during forming of automotive body, Limit Dome Height (LDH) tests were conducted and samples were deformed in servo hydraulic press to find the different strain path. FEM Simulations were done to predict different strain path diagrams and compared with experimental results. There is a significant difference between experimental and simulation results as the existing material models are not applicable for TRIP steels. Micro texture studies were performed on the samples using EBSD and X-RD techniques. It was observed that austenite is transformed to martensite and texture developed during deformation had strong impact on limit strain and strain path. (paper)

  17. Texture developed during deformation of Transformation Induced Plasticity (TRIP) steels

    Science.gov (United States)

    Bhargava, M.; Shanta, C.; Asim, T.; Sushil, M.

    2015-04-01

    Automotive industry is currently focusing on using advanced high strength steels (AHSS) due to its high strength and formability for closure applications. Transformation Induced Plasticity (TRIP) steel is promising material for this application among other AHSS. The present work is focused on the microstructure development during deformation of TRIP steel sheets. To mimic complex strain path condition during forming of automotive body, Limit Dome Height (LDH) tests were conducted and samples were deformed in servo hydraulic press to find the different strain path. FEM Simulations were done to predict different strain path diagrams and compared with experimental results. There is a significant difference between experimental and simulation results as the existing material models are not applicable for TRIP steels. Micro texture studies were performed on the samples using EBSD and X-RD techniques. It was observed that austenite is transformed to martensite and texture developed during deformation had strong impact on limit strain and strain path.

  18. Effects of B2 precipitate size on transformation-induced plasticity of Cu–Zr–Al glassy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, C.N. [Department of Materials and Optoelectronic Science, Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Huang, J.C., E-mail: jacobc@mail.nsysu.edu.tw [Department of Materials and Optoelectronic Science, Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Li, J.B.; Jang, J.S.C. [Institute of Materials Science and Engineering, Department of Mechanical Engineering, National Central University, Chung-Li, Taiwan, ROC (China); Lin, C.H. [Department of Mechanical and Electromechanical Engineering, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Nieh, T.G. [Department of Materials and Optoelectronic Science, Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States)

    2014-03-25

    Highlights: • This paper addresses the effects of the CuZr B2 size and distribution on plasticity. • There is a critical size to induce the martensitic/twinning transformation. • An analytic model based on melt flow dynamics is settled. -- Abstract: To demonstrate the effect of processing on the microstructure and subsequent mechanical property of bulk metallic glasses, we prepared two alloys, Cu{sub 47.5}Zr{sub 47.5}Al{sub 5} and Cu{sub 47.5}Zr{sub 48}Al{sub 4}Co{sub 0.5}, using two different designs of suction mold – one with a sharp inlet and one with a blunt inlet. The two alloys have been demonstrated previously to be ductile via phase transformation of the B2 phase and twin formation during plastic deformation. Microstructures of the as-cast as well plastically deformed samples, in particular, the size and distribution of the B2 phase, were examined using X-ray diffraction, scanning and transmission electron microscopy. Compressive tests were conducted on samples cast by different molds and their properties were found to closely correlate with the B2 morphology. Fluid dynamics during suction casting was also analyzed. Effects of Vena contracta, flow velocity, and Reynolds number were discussed and compared favorably with experimental observations.

  19. Mechanically induced atomic disorder and phase transformations. Doctoral thesis

    Energy Technology Data Exchange (ETDEWEB)

    Limei, D

    1992-11-30

    The study shows the possibilities of preparing alloys in various metastable configurations by the simple technique of ball milling. Firstly, chapter 2 gives the description of experimental techniques. In chapter 3, evidence of atomic anti-site disordering in A15-structure superconducting compounds Nb3Sn and Nb3Au during an early stage of milling is demonstrated. Chapter 4 represents the experimental results on the B2-structure magnetic compounds CoGa and CoAl upon mechanical impact. These compounds are well known for their particular type of atomic disorder, namely triple-defect disorder. Various examples of experimental evidence of phase transformations induced by mechanical grinding are presented in chapter 5. Section 5.2 gives an example of amorphization induced by mechanical attrition in the intermetallic compound Ni3Sn. Section 5.3 shows the milling experiment of the intermetallic compound V3 Ga. In section 5.4, for the first time, the observation of a phase transformation to a high-temperature phase with a complex structure will be demonstrated for the intermetallic compound Co3Sn2. In the last chapter, detailed studies on the intermetallic Nb-Au binary compounds for a variety of compositions are presented.

  20. Collision-induced dissociation with Fourier transform mass spectrometry

    International Nuclear Information System (INIS)

    Cody, R.B.; Burnier, R.C.; Freiser, B.S.

    1982-01-01

    Collision-induced dissociations (CID) is demonstrated on a number of primary and secondary ions using a Nicolet prototype Fourier transform mass spectrometer (FT-MS). Like the triple quadrupole technique, CID using FT-MS is a relatively low energy and efficient process. The ability to study a wide range of ion-molecule reaction products is exemplified by results on proton-bound dimers and transition metal containing ionic species. Variation of collision energy by varying the RF irradiation level can provide information about product distributions as a function of energy as well as yield ion structural information. Like the triple quadrupole technique, no slits are employed and virtually all of the fragment ions formed by the CID process may be detected. Unlike all previous mass spectrometric techniques for studying CID, a tandem instrument is not required, and different experiments are performed by making software modifications rather than hardware modifications

  1. Ductile failure modeling

    DEFF Research Database (Denmark)

    Benzerga, Ahmed Amine; Leblond, Jean Baptiste; Needleman, Alan

    2016-01-01

    Ductile fracture of structural metals occurs mainly by the nucleation, growth and coalescence of voids. Here an overview of continuum models for this type of failure is given. The most widely used current framework is described and its limitations discussed. Much work has focused on extending void...... growth models to account for non-spherical initial void shapes and for shape changes during growth. This includes cases of very low stress triaxiality, where the voids can close up to micro-cracks during the failure process. The void growth models have also been extended to consider the effect of plastic...... anisotropy, or the influence of nonlocal effects that bring a material size scale into the models. Often the voids are not present in the material from the beginning, and realistic nucleation models are important. The final failure process by coalescence of neighboring voids is an issue that has been given...

  2. Hot Ductility Behavior of an 8 Pct Cr Roller Steel

    Science.gov (United States)

    Wang, Zhenhua; Sun, Shuhua; Shi, Zhongping; Wang, Bo; Fu, Wantang

    2015-04-01

    The hot ductility of an 8 pct Cr roller steel was determined between 1173 K and 1473 K (900 °C and 1200 °C) at strain rates of 0.01 to 10 s-1 through tensile testing. The fracture morphology was observed using scanning electron microscopy, and the microstructure was examined through optical microscopy and transmission electron microscopy. The dependence of the hot ductility behavior on the deformation conditions, grain size, and precipitation was analyzed. The relationship between the reduction in area and the natural logarithm of the Zener-Hollomon parameter (ln Z) was found to be a second-order polynomial. When ln Z was greater than 40 s-1, the hot ductility was poor and fracture was mainly caused by incompatible deformation between the grains. When ln Z was between 32 and 40 s-1, the hot ductility was excellent and the main fracture mechanism was void linking. When ln Z was below 32 s-1, the hot ductility was poor and fracture was mainly caused by grain boundary sliding. A fine grain structure is beneficial for homogenous deformation and dynamic recrystallization, which induces better hot ductility. The effect of M7C3 carbide particles dispersed in the matrix on the hot ductility was small. The grain growth kinetics in the 8 pct Cr steel were obtained between 1373 K and 1473 K (1100 °C and 1200 °C). Finally, optimized preheating and forging procedures for 8 pct Cr steel rollers are provided.

  3. Vacancy-induced brittle to ductile transition of W-M co-doped Al3Ti (M=Si, Ge, Sn and Pb).

    Science.gov (United States)

    Zhu, Mingke; Wu, Ping; Li, Qiulin; Xu, Ben

    2017-10-25

    We investigated the effect of vacancy formation on brittle (D0 22 ) to ductile (L1 2 -like) transition in Al 3 Ti using DFT calculations. The well-known pseudogap on the density of states of Al 3 Ti migrates towards its Fermi level from far above, via a W - M co-doping strategy, where M is Si, Ge, Sn or Pb respectively. In particular, by a W - M co-doping the underline electronic structure of the pseudogap approaches an octahedral (L1 2 : t 2g , e g ) from the tetragonal (D0 22 : e g , b 2g , a 1g , b 1g ) crystal field. Our calculations demonstrated that (1) a W-doping is responsible for the close up of the energy gap between a 1g and b 1g so that they tend to merge into an e g symmetry, and (2) all M-doping lead to a narrower gap between e g and b 2g (moving towards a t 2g symmetry). Thus, a brittle to ductile transition in Al 3 Ti is possible by adopting this W - M co-doping strategy. We further recommend the use of W-Pb co-doped Al 3 Ti to replace the less anodic Al electrode in Al-battery, due to its improved ductility and high Al diffusivity. Finally this study opens a new field in physics to tailor mechanical properties by manipulating electron energy level(s) towards higher symmetry via vacancy optimization.

  4. Kinetics of hydrothermally induced transformation of yttria partially stabilized zirconia

    International Nuclear Information System (INIS)

    Payyapilly, J.J.; Butt, D.P.

    2007-01-01

    Yttria-stabilized zirconia undergoes tetragonal to monoclinic phase transformation under hydrothermal conditions in the temperature range of 150-350 deg. C. Phase transformation accompanied by volume change in bulk yttria partially stabilized zirconia (YPSZ) leads to micro-cracking, loss of mechanical integrity and ultimately disintegration. The mechanical properties of the bulk YPSZ material deteriorate with the amount of the phase transformation and in some cases catastrophic failure are observed. The phase transformation is analyzed using macroscopic and microscopic techniques. X-ray diffraction data is used to quantify the phase transformation in bulk material. Kinetics of the phase transformation is studied at various temperatures

  5. Mechanical model for ductility loss

    International Nuclear Information System (INIS)

    Hu, W.L.

    1980-01-01

    A mechanical model was constructed to probe into the mechanism of ductility loss. Fracture criterion based on critical localized deformation was undertaken. Two microstructure variables were considered in the model. Namely, the strength ratio of grain boundary affected area to the matrix, Ω, and the linear fraction, x, of grain boundary affected area. A parametrical study was carried out. The study shows that the ductility is very sensitive to those microstructure parameters. The functional dependence of ductility to temperature as well as strain-rate, suggested by the model, is demonstrated to be consistent with the observation

  6. A new effect of retained austenite on ductility enhancement in high strength bainitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Wang Ying; Zhang Ke; Guo Zhenghong; Chen Nailu [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Rong Yonghua, E-mail: yhrong@sjtu.edu.cn [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2012-08-30

    Highlights: Black-Right-Pointing-Pointer A new DARA effect in the bainitic steel is proposed. Black-Right-Pointing-Pointer The conditions of DARA effect are proposed. Black-Right-Pointing-Pointer The mechanism of retained austenite on ductility enhancement is clarified. - Abstract: A designed high strength bainitic steel with considerable amount of retained austenite is presented in order to study the effect of retained austenite on the ductility enhancement in bainitic steels. Transformation induced plasticity (TRIP) effect is verified by both X-ray diffraction (XRD) measurement of retained austenite fraction in various deformation stages and transmission electron microscopy observation of the deformed twin-type martensite. Results from XRD line profile analysis reveal that the average dislocation density in bainite during the deformation is lower than that before deformation, and such a phenomenon can be explained by a new effect, dislocations absorption by retained austenite (DARA) effect, based on our previous investigation of martensitic steels. DARA effect availably enhances the compatibility of deformation ability of bainite with retained austenite. In view of microstructure similarity of bainitic steels with martensitic steels, the conditions of DARA effect are proposed. The effects of retained austenite on the ductility enhancement in bainitic steels are clarified.

  7. Uncovering the local inelastic interactions during manufacture of ductile cast iron: How the substructure of the graphite particles can induce residual stress concentrations in the matrix

    DEFF Research Database (Denmark)

    Andriollo, Tito; Hellström, Kristina; Sonne, Mads Rostgaard

    2018-01-01

    Recent X-ray diffraction (XRD) measurements have revealed that plastic deformation and a residual elastic strain field can be present around the graphite particles in ductile cast iron after manufacturing, probably due to some local mismatch in thermal contraction. However, as only one component...... of the elastic strain tensor could be obtained from the XRD data, the shape and magnitude of the associated residual stress field have remained unknown. To compensate for this and to provide theoretical insight into this unexplored topic, a combined experimental-numerical approach is presented in this paper...... the graphite particles and the matrix during manufacturing of the industrial part considered in the XRD study. The model indicates that, besides the vis- coplastic deformation of the matrix, the effect of the inelastic deformation of the graphite has to be considered to explain the magnitude of the XRD strain...

  8. Crystallographically based model for transformation-induced plasticity in multiphase carbon steels

    NARCIS (Netherlands)

    Tjahjanto, D.D.; Turteltaub, S.; Suiker, A.S.J.

    2007-01-01

    The microstructure of multiphase steels assisted by transformation-induced plasticity consists of grains of retained austenite embedded in a ferrite-based matrix. Upon mechanical loading, retained austenite may transform into martensite, as a result of which plastic deformations are induced in the

  9. Crystallographically based model for transformation-induced plasticity in multiphase carbon steels

    NARCIS (Netherlands)

    Tjahjanto, D.D.; Turteltaub, S.R.; Suiker, A.S.J.

    2008-01-01

    The microstructure of multiphase steels assisted by transformation-induced plasticity consists of grains of retained austenite embedded in a ferrite-based matrix. Upon mechanical loading, retained austenite may transform into martensite, as a result of which plastic deformations are induced in the

  10. Investigation of protection problems due to geomagnetically induced currents (solar magnetic disturbances, transformers)

    International Nuclear Information System (INIS)

    1997-01-01

    The problems with geomagnetically induced currents (GIC) flowing in power systems during solar magnetic disturbances were studied. Transformers can overheat as a result of GIC because they can cause offset saturation of power system transformers. Harmonic currents can also be introduced into the system which then affect the relay and protection systems. Several studies have been conducted using simplified transformer core models to predict the transformer response to DC excitation. In this study, an accurate transformer core model was developed and validated by comparing the recorded waveforms during GIC events with simulated waveforms using the model. The new transformer core model was used to evaluate the performance of different protection schemes under GIC

  11. Ductile Fracture Behaviour of Hot Isostatically Pressed Inconel 690 Superalloy

    Science.gov (United States)

    Cooper, A. J.; Brayshaw, W. J.; Sherry, A. H.

    2018-04-01

    Herein we assess the differences in Charpy impact behavior between Hot Isostatically Pressed and forged Inconel 690 alloy over the temperature range of 300 °C to - 196 °C. The impact toughness of forged 690 exhibited a relatively small temperature dependence, with a maximum difference of ca. 40 J measured between 300 °C and - 196 °C, whereas the HIP'd alloy exhibited a difference of approximately double that of the forged alloy over the same temperature range. We have conducted Charpy impact testing, tensile testing, and metallographic analyses on the as-received materials as well as fractography of the failed Charpy specimens in order to understand the mechanisms that cause the observed differences in material fracture properties. The work supports a recent series of studies which assess differences in fundamental fracture behavior between Hot Isostatically Pressed and forged austenitic stainless steel materials of equivalent grades, and the results obtained in this study are compared to those of the previous stainless steel investigations to paint a more general picture of the comparisons between HIP vs forged material fracture behavior. Inconel 690 was selected in this study since previous studies were unable to completely omit the effects of strain-induced martensitic transformation at the tip of the Chary V-notch from the fracture mechanism; Inconel 690 is unable to undergo strain-induced martensitic transformation due to the alloy's high nickel content, thereby providing a sister study with the omission of any martensitic transformation effects on ductile fracture behavior.

  12. Pressure-induced structural phase transformation and superconducting properties of titanium mononitride

    Science.gov (United States)

    Li, Qian; Guo, Yanan; Zhang, Miao; Ge, Xinlei

    2018-03-01

    In this work, we have systematically performed the first-principles structure search on titanium mononitride (TiN) within Crystal Structure AnaLYsis by Particle Swarm Optimization (CALYPSO) methodology at high pressures. Here, we have confirmed a phase transition from cubic rock-salt (fcc) phase to CsCl (bcc) phase of TiN at ∼348 GPa. Further simulations reveal that the bcc phase is dynamically stable, and could be synthesized experimentally in principle. The calculated elastic anisotropy decreases with the phase transformation from fcc to bcc structure under high pressures, and the material changes from ductile to brittle simultaneously. Moreover, we found that both structures are superconductive with the superconducting critical temperature of 2-12 K.

  13. Role of thyroid in x-ray-induced oncogenic transformation in cell culture

    International Nuclear Information System (INIS)

    Borek, C.

    1982-01-01

    This paper examines the role of thyroid hormones in x-ray-induced neoplastic transformation of C3H/10 T 1/2 cells. In addition, the delineation of the time when transformation is sensitive to T3, the dependence of transformation on T3 concentration, and the involvement of protein synthesis are studied. The results indicate that thyroid hormone plays a key role in the initiation of x-ray-induced neoplastic transformation and that induction of protein synthesis may mediate this response

  14. Evaluation of a Ductility after High Temperature Oxidation with the Three-Point Bend Test in Zirconium Alloys

    International Nuclear Information System (INIS)

    Jung, Yang Il; Park, Sang Yoon; Park, Jeong Yong; Jeong, Yong Hwan

    2010-01-01

    In a light water reactor, the fuel cladding play an important role of preventing leakage of radioactive materials into the coolant, and thus the mechanical integrity of the cladding should be guaranteed under the conditions of normal and transient operation. In the case of a loss of coolant accident (LOCA), the cladding is subjected to a high temperature oxidation which is finally quenched because of an emergency coolant reflooding into the core. In this situation, the current LOCA criteria consist of five separate requirements: i) peak cladding temperature, ii) maximum cladding oxidation, iii) maximum hydrogen generation, iv) coolable geometry, and v) long-term cooling. The claddings lose their ductility due to the microstructural phase transformation from beta to martensite alpha-prime. and hydrogen up-take after LOCA. Since the reduction in ductility can induce embrittlement of claddings, post-quench ductility is one of the major concerns in transient operation circumstances. For the analysis, usually ring compression test are performed on ring samples cut from the tube to examine the oxidized cladding ductility. However, the test would not be applicable to the platelet samples which are general form of a specimen for developing alloys. As a high burn-up fuel cladding materials, Zircaloys are being replaced by modern zirconium alloys such as ZIRLO, and M5. Korea has also developed a new fuel cladding material HANA (high performance alloy for nuclear application) by the Korea Atomic Energy Research Institute. Because of the different composition of the newer claddings in comparison with the conventional Zircaloy-4, the high temperature oxidation behavior and the ductility after the oxidation would be different, and the properties should be evaluated how much the newer claddings were improved

  15. A macroscopic model to simulate the mechanically induced martensitic transformation in metastable austenitic stainless steels

    International Nuclear Information System (INIS)

    Perdahcıoğlu, E.S.; Geijselaers, H.J.M.

    2012-01-01

    Mechanically induced martensitic transformation and the associated transformation plasticity phenomena in austenitic stainless steels are studied. The mechanisms responsible for the transformation are investigated and put into perspective based on experimental evidence. The stress and strain partitioning into the austenite and martensite phases are formulated using a mean-field homogenization approach. At this intermediate length-scale the average stress in the austenite phase is computed and utilized to compute the mechanical driving force resolved in the material. The amount of transformation and the transformation plasticity is derived as a function of the driving force. The mechanical response of the material is obtained by combining the homogenization and the transformation models. The model is verified by mechanical tests under biaxial loading conditions during which different transformation rates are observed. As a final verification of the model, a bending test is used which manifests the stress-state dependency of the transformation.

  16. Transformation between divacancy defects induced by an energy pulse in graphene.

    Science.gov (United States)

    Xia, Jun; Liu, XiaoYi; Zhou, Wei; Wang, FengChao; Wu, HengAn

    2016-07-08

    The mutual transformations among the four typical divacancy defects induced by a high-energy pulse were studied via molecular dynamics simulation. Our study revealed all six possible mutual transformations and found that defects transformed by absorbing energy to overcome the energy barrier with bonding, debonding, and bond rotations. The reversibility of defect transformations was also investigated by potential energy analysis. The energy difference was found to greatly influence the transformation reversibility. The direct transformation path was irreversible if the energy difference was too large. We also studied the correlation between the transformation probability and the input energy. It was found that the transformation probability had a local maxima at an optimal input energy. The introduction of defects and their structural evolutions are important for tailoring the exceptional properties and thereby performances of graphene-based devices, such as nanoporous membranes for the filtration and desalination of water.

  17. Radiation-induced transformation in oncogene primed C3H/10T1/2 cells; a new system for analysis of multi-step transformation in vitro

    International Nuclear Information System (INIS)

    Drozdoff, V.V.

    1988-01-01

    Several established rodent cell lines, such as C3H/10T1/2 fibroblasts, have been developed to study radiation and chemically-induced malignant transformation. Most experimental evidence has supported the idea that transformation in 10T1/2 cells involved at least two steps but that the apparent frequency of transformation depends on the density of plated cells. A new approach is presented here for studying radiation-induced transformation. An oncogene primed cell system (C3H-myc) was developed by introducing a constitutively active mouse c-myc gene into 10T1/2 cells. A primary goal was to determine if the introduction of an activated oncogene could substitute for one of the required steps in radiation-induced transformation. Results are presented that show that the expression of the exogenous myc gene significantly increased the frequency of radiation-induced transformation in these cells. Subculture experiments performed to analyze the kinetics of transformation in C3H-myc cells and reconstruction experiments allowing the effects of normal cells on radiation-induced transformants to be determined indicated that transformed cells arose very shortly after irradiation. These results support the conclusion that a radiation-induced event can complement the effect of myc in C3H-myc cells and directly result in transformation. This system thus provides an opportunity to isolate early steps in radiation-induced transformation and should facilitate the identification and analysis of these events

  18. Chemically Induced Phase Transformation in Austenite by Focused Ion Beam

    Science.gov (United States)

    Basa, Adina; Thaulow, Christian; Barnoush, Afrooz

    2014-03-01

    A highly stable austenite phase in a super duplex stainless steel was subjected to a combination of different gallium ion doses at different acceleration voltages. It was shown that contrary to what is expected, an austenite to ferrite phase transformation occurred within the focused ion beam (FIB) milled regions. Chemical analysis of the FIB milled region proved that the gallium implantation preceded the FIB milling. High resolution electron backscatter diffraction analysis also showed that the phase transformation was not followed by the typical shear and plastic deformation expected from the martensitic transformation. On the basis of these observations, it was concluded that the change in the chemical composition of the austenite and the local increase in gallium, which is a ferrite stabilizer, results in the local selective transformation of austenite to ferrite.

  19. Relationship between hydrogen-induced phase transformations and pitting nucleation sites in duplex stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Liqiu; Yang, Binjie; Qin, Sixiao [University of Science and Technology Beijing (China). Corrosion and Protection Center

    2016-02-15

    This paper demonstrates the hydrogen-induced phase transformation and the associated pitting nucleation sites of 2507 duplex stainless steel using scanning Kelvin probe force microscopy and magnetic force microscopy. The low potential sites in Volta potential images, which are considered as the pitting nucleation sites, are strongly dependent on the hydrogen-induced phase transformation. They firstly initiate on the magnetic martensite laths in the austenite phase or at the ferrite/austenite boundaries, and then appear near the needle-shaped microtwins in the ferrite phase, because of the difference in physicochemical properties of hydrogen-induced phase transformation microstructures.

  20. Transformation

    DEFF Research Database (Denmark)

    Bock, Lars Nicolai

    2011-01-01

    Artiklen diskuterer ordet "transformation" med udgangspunkt i dels hvorledes ordet bruges i arkitektfaglig terminologi og dels med fokus på ordets potentielle indhold og egnethed i samme teminologi.......Artiklen diskuterer ordet "transformation" med udgangspunkt i dels hvorledes ordet bruges i arkitektfaglig terminologi og dels med fokus på ordets potentielle indhold og egnethed i samme teminologi....

  1. TRANSFORMATION

    Energy Technology Data Exchange (ETDEWEB)

    LACKS,S.A.

    2003-10-09

    Transformation, which alters the genetic makeup of an individual, is a concept that intrigues the human imagination. In Streptococcus pneumoniae such transformation was first demonstrated. Perhaps our fascination with genetics derived from our ancestors observing their own progeny, with its retention and assortment of parental traits, but such interest must have been accelerated after the dawn of agriculture. It was in pea plants that Gregor Mendel in the late 1800s examined inherited traits and found them to be determined by physical elements, or genes, passed from parents to progeny. In our day, the material basis of these genetic determinants was revealed to be DNA by the lowly bacteria, in particular, the pneumococcus. For this species, transformation by free DNA is a sexual process that enables cells to sport new combinations of genes and traits. Genetic transformation of the type found in S. pneumoniae occurs naturally in many species of bacteria (70), but, initially only a few other transformable species were found, namely, Haemophilus influenzae, Neisseria meningitides, Neisseria gonorrheae, and Bacillus subtilis (96). Natural transformation, which requires a set of genes evolved for the purpose, contrasts with artificial transformation, which is accomplished by shocking cells either electrically, as in electroporation, or by ionic and temperature shifts. Although such artificial treatments can introduce very small amounts of DNA into virtually any type of cell, the amounts introduced by natural transformation are a million-fold greater, and S. pneumoniae can take up as much as 10% of its cellular DNA content (40).

  2. A brittle-fracture methodology for three-dimensional visualization of ductile deformation micromechanisms

    NARCIS (Netherlands)

    Tasan, C.C.; Hoefnagels, J.P.M.; Geers, M.G.D.

    2009-01-01

    An improved experimental methodology is developed and successfully evaluated to visualize deformation-induced microevents in ductile sheet metal. This easy-to-use methodology consists in a well-controlled brittle separation of samples previously deformed in a ductile manner, whereby a

  3. Alpha-particles induce preneoplastic transformation of rat tracheal epithelial cells in culture

    International Nuclear Information System (INIS)

    Thomassen, D.G.; Seiler, F.A.; Shyr, L.-J.; Griffith, W.C.

    1990-01-01

    To characterize the potential role of high-l.e.t. radiation in respiratory carcinogenesis, the cytotoxic and transforming potency of 5.5 MeV α-particles from electroplated sources of 238 Pu were determined using primary cultures of rat tracheal epithelial cells. RBE for cell killing by α-particles versus X-rays varied with dose, and ranged between 4 and 1.5 for α doses in the range 0.2-4 Gy. At equally toxic doses (relative survival 0.18-0.2), all three agents induced similar frequencies of preneoplastic transformation. For preneoplastic transformation induced by doses of α- and X-radiations giving 80 per cent toxicity, an α RBE of 2.4 was derived. The similar RBEs for cell killing and for preneoplastic transformation suggest an association between the type or degree of radiation-induced damage responsible for both cell killing and cell transformation. (author)

  4. TRANSFORMER

    Science.gov (United States)

    Baker, W.R.

    1959-08-25

    Transformers of a type adapted for use with extreme high power vacuum tubes where current requirements may be of the order of 2,000 to 200,000 amperes are described. The transformer casing has the form of a re-entrant section being extended through an opening in one end of the cylinder to form a coaxial terminal arrangement. A toroidal multi-turn primary winding is disposed within the casing in coaxial relationship therein. In a second embodiment, means are provided for forming the casing as a multi-turn secondary. The transformer is characterized by minimized resistance heating, minimized external magnetic flux, and an economical construction.

  5. Investigation of hot ductility in Al-killed boron steels

    International Nuclear Information System (INIS)

    Chown, L.H.; Cornish, L.A.

    2008-01-01

    The influence of boron to nitrogen ratio, strain rate and cooling rate on hot ductility of aluminium-killed, low carbon, boron microalloyed steel was investigated. Hot tensile testing was performed on steel samples reheated in argon to 1300 deg. C, cooled at rates of 0.3, 1.2 and 3.0 deg. C s -1 to temperatures in the range 750-1050 deg. C, and then strained to failure at initial strain rates of 1 x 10 -4 or 1 x 10 -3 s -1 . It was found that the steel with a B:N ratio of 0.19 showed deep hot ductility troughs for all tested conditions; the steel with a B:N ratio of 0.47 showed a deep ductility trough for a high cooling rate of 3.0 deg. C s -1 and the steel with a near-stoichiometric B:N ratio of 0.75 showed no ductility troughs for the tested conditions. The ductility troughs extended from ∼900 deg. C (near the Ae 3 temperature) to ∼1000 or 1050 deg. C in the single-phase austenite region. The proposed mechanism of hot ductility improvement with increase in B:N ratio in these steels is that the B removes N from solution, thus reducing the strain-induced precipitation of AlN. Additionally, BN co-precipitates with sulphides, preventing precipitation of fine MnS, CuS and FeS, and forming large, complex precipitates that have no effect on hot ductility

  6. Intrinsic ductility and environmental embrittlement of binary Ni3Al

    International Nuclear Information System (INIS)

    George, E.P.; Liu, C.T.; Pope, D.P.

    1993-01-01

    Polycrystalline, B-free Ni 3 Al (23.4 at.% Al), produced by cold working and recrystallizing a single crystal, exhibits room temperature tensile ductilities of 3-5% in air and 13-16% in oxygen. These ductilities are considerably higher than anything previously reported, and demonstrate that the 'intrinsic' ductility of Ni 3 Al is much higher than previously thought. They also show that the moisture present in ordinary ambient air can severely embrittle Ni 3 Al (ductility decreasing from a high of 16% in oxygen to a low of 3% in air). Fracture is predominantly intergranular in both air and oxygen. This indicates that, while moisture can further embrittle the GBs in Ni 3 Al, they persist as weak links even in the absence of environmental embrittlement. However, they are not 'intrinsically brittle' as once thought, since they can withstand relatively large plastic deformations prior to fracture. Because B essentially eliminates environmental embrittlement in Ni 3 Al - and environmental embrittlement is a major cause of poor ductility in B-free Ni 3 Al - it is concluded that a significant portion of the so-called B effect must be related to suppression of moisture-induced environmental embrittlement. However, since B-doped Ni 3 Al fractures transgranularly, whereas B-free Ni 3 Al fractures predominantly intergranularly, B must have the added effect that it strengthens the GBs. A comparison with the earlier work on Zr-doped Ni 3 Al shows that Zr improves the ductility of Ni 3 Al, both in air and (and even more dramatically) in oxygen. While the exact mechanism of this ductility improvement is not clear at present, Zr appears to have more of an effect on (enhancing) GB strength than on (suppressing) environmental embrittlement

  7. [Malignant transformation of human fibroblasts by neutrons and by gamma radiation: Relationship to mutations induced

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1993-12-31

    A brief overview if provided of selected reports presented at the International Symposium on Molecular Mechanisms of Radiation- and Chemical Carcinogen-Induced Cell Transformation held at Mackinac Island, Michigan on September 19-23, 1993.

  8. Transformation-induced plasticity in multiphase steels subjected to thermomechanical loading

    NARCIS (Netherlands)

    Tjahjanto, D.D.; Turteltaub, S.R.; Suiker, A.S.J.; Zwaag, van der S.

    2008-01-01

    The behaviour of transformation-induced plasticity steels subjected to combined thermomechanical loading is studied at the microscale by means of numerical simulations. The microstructure is composed of an austenitic phase that may deform plastically and/or transform into martensite, and a ferritic

  9. First interactions between hydrogen and stress-induced reverse transformation of Ni-Ti superelastic alloy

    Science.gov (United States)

    Yokoyama, Ken'ichi; Hashimoto, Tatsuki; Sakai, Jun'ichi

    2017-11-01

    The first dynamic interactions between hydrogen and the stress-induced reverse transformation have been investigated by performing an unloading test on a Ni-Ti superelastic alloy subjected to hydrogen charging under a constant applied strain in the elastic deformation region of the martensite phase. Upon unloading the specimen, charged with a small amount of hydrogen, no change in the behaviour of the stress-induced reverse transformation is observed in the stress-strain curve, although the behaviour of the stress-induced martensite transformation changes. With increasing amount of hydrogen charging, the critical stress for the reverse transformation markedly decreases. Eventually, for a larger amount of hydrogen charging, the reverse transformation does not occur, i.e. there is no recovery of the superelastic strain. The residual martensite phase on the side surface of the unloaded specimen is confirmed by X-ray diffraction. Upon training before the unloading test, the properties of the reverse transformation slightly recover after ageing in air at room temperature. The present study indicates that to change the behaviour of the reverse transformation a larger amount of hydrogen than that for the martensite transformation is necessary. In addition, it is likely that a substantial amount of hydrogen in solid solution more strongly suppresses the reverse transformation than hydrogen trapped at defects, thereby stabilising the martensite phase.

  10. Development of a kinetic model for bainitic isothermal transformation in transformation-induced plasticity steels

    International Nuclear Information System (INIS)

    Li, S.; Zhu, R.; Karaman, I.; Arróyave, R.

    2013-01-01

    In this work, we modify existing models to simulate the kinetics of bainitic transformation during the bainitic isothermal transformation (BIT) stage of a typical two-stage heat treatment – BIT is preceded by an intercritical annealing treatment – for TRIP steels. This effort is motivated by experiments performed in a conventional TRIP steel alloy (Fe–0.32C–1.42Mn–1.56Si) that suggest that thermodynamics alone are not sufficient to predict the amount of retained austenite after BIT. The model implemented in this work considers the non-homogeneous distribution of carbon – resulting from finite carbon diffusion rates – within the retained austenite during bainitic transformation. This non-homogeneous distribution is responsible for average austenite carbon enrichments beyond the so-called T 0 line, the temperature at which the chemical driving force for the bainitic transformation is exhausted. In order to attain good agreement with experiments, the existence of carbon-rich austenite films adjacent to bainitic ferrite plates is posited. The presence of this austenite film is motivated by earlier experimental work published by other groups in the past decade. The model is compared with experimental results and good qualitative agreement is found

  11. Comparative genome analysis of three eukaryotic parasites with differing abilities to transform leukocytes reveals key mediators of theileria-induced leukocyte transformation

    KAUST Repository

    Hayashida, Kyoko; Hara, Yuichiro; Abe, Takashi; Yamasaki, Chisato; Toyoda, Atsushi; Kosuge, Takehide; Suzuki, Yutaka; Sato, Yoshiharu; Kawashima, Shuichi; Katayama, Toshiaki; Wakaguri, Hiroyuki; Inoue, Noboru; Homma, Keiichi; Tada-Umezaki, Masahito; Yagi, Yukio; Fujii, Yasuyuki; Habara, Takuya; Kanehisa, Minoru; Watanabe, Hidemi; Ito, Kimihito; Gojobori, Takashi; Sugawara, Hideaki; Imanishi, Tadashi; Weir, William; Gardner, Malcolm; Pain, Arnab; Shiels, Brian; Hattori, Masahira; Nene, Vishvanath; Sugimoto, Chihiro

    2012-01-01

    . annulata. T. parva and T. annulata induce transformation of infected cells of lymphocyte or macrophage/monocyte lineages; in contrast, T. orientalis does not induce uncontrolled proliferation of infected leukocytes and multiplies predominantly within

  12. A new insight into ductile fracture of ultrafine-grained Al-Mg alloys.

    Science.gov (United States)

    Yu, Hailiang; Tieu, A Kiet; Lu, Cheng; Liu, Xiong; Liu, Mao; Godbole, Ajit; Kong, Charlie; Qin, Qinghua

    2015-04-08

    It is well known that when coarse-grained metals undergo severe plastic deformation to be transformed into nano-grained metals, their ductility is reduced. However, there are no ductile fracture criteria developed based on grain refinement. In this paper, we propose a new relationship between ductile fracture and grain refinement during deformation, considering factors besides void nucleation and growth. Ultrafine-grained Al-Mg alloy sheets were fabricated using different rolling techniques at room and cryogenic temperatures. It is proposed for the first time that features of the microstructure near the fracture surface can be used to explain the ductile fracture post necking directly. We found that as grains are refined to a nano size which approaches the theoretical minimum achievable value, the material becomes brittle at the shear band zone. This may explain the tendency for ductile fracture in metals under plastic deformation.

  13. Pressure-induced transformations in amorphous silicon: A computational study

    Energy Technology Data Exchange (ETDEWEB)

    Garcez, K. M. S., E-mail: kmgarcez@ufma.br [Universidade Federal do Maranhão, 65700-000 Bacabal, Maranhão (Brazil); Antonelli, A., E-mail: aantone@ifi.unicamp.br [Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, UNICAMP, 13083-859 Campinas, São Paulo (Brazil)

    2014-02-14

    We study the transformations between amorphous phases of Si through molecular simulations using the environment dependent interatomic potential (EDIP) for Si. Our results show that upon pressure, the material undergoes a transformation from the low density amorphous (LDA) Si to the high density amorphous (HDA) Si. This transformation can be reversed by decompressing the material. This process, however, exhibits clear hysteresis, suggesting that the transformation LDA ↔ HDA is first-order like. The HDA phase is predominantly five-fold coordinated, whereas the LDA phase is the normal tetrahedrally bonded amorphous Si. The HDA phase at 400 K and 20 GPa was submitted to an isobaric annealing up to 800 K, resulting in a denser amorphous phase, which is structurally distinct from the HDA phase. Our results also show that the atomic volume and structure of this new amorphous phase are identical to those of the glass obtained by an isobaric quenching of the liquid in equilibrium at 2000 K and 20 GPa down to 400 K. The similarities between our results and those for amorphous ices suggest that this new phase is the very high density amorphous Si.

  14. Pressure-induced transformations in amorphous silicon: A computational study

    Science.gov (United States)

    Garcez, K. M. S.; Antonelli, A.

    2014-02-01

    We study the transformations between amorphous phases of Si through molecular simulations using the environment dependent interatomic potential (EDIP) for Si. Our results show that upon pressure, the material undergoes a transformation from the low density amorphous (LDA) Si to the high density amorphous (HDA) Si. This transformation can be reversed by decompressing the material. This process, however, exhibits clear hysteresis, suggesting that the transformation LDA ↔ HDA is first-order like. The HDA phase is predominantly five-fold coordinated, whereas the LDA phase is the normal tetrahedrally bonded amorphous Si. The HDA phase at 400 K and 20 GPa was submitted to an isobaric annealing up to 800 K, resulting in a denser amorphous phase, which is structurally distinct from the HDA phase. Our results also show that the atomic volume and structure of this new amorphous phase are identical to those of the glass obtained by an isobaric quenching of the liquid in equilibrium at 2000 K and 20 GPa down to 400 K. The similarities between our results and those for amorphous ices suggest that this new phase is the very high density amorphous Si.

  15. Plasticity induced by phase transformation in steel: experiment vs modeling

    International Nuclear Information System (INIS)

    Tahimi, Abdeladhim

    2011-01-01

    The objectives of this work are: (i) understand the mechanisms and phenomena involved in the plasticity of steels in the presence of a diffusive or martensitic phase transformation. (ii) develop tools for predicting TRIP, which are able to correctly reproduce the macroscopic deformation for cases of complex loading and could also provide information about local elasto-visco-plastic interactions between product and parent phases. To this purpose, new experimental tests are conducted on 35NCD16 steel for austenite to martensite transformation and on 100C6 steel for austenite to pearlite transformation. The elasto viscoplastic properties of austenite and pearlite of the 100C6 steel are characterized through tension compression and relaxation tests. The parameters of macro-homogeneous and crystal-based constitutive laws could then be identified such as to analyse different models with respect to the experimental TRIP: the analytical models of Leblond (1989) and Taleb and Sidoroff (2003) but also, above all, different numerical models which can be distinguished by the prevailing assumptions concerning the local kinetics and the constitutive laws. An extension of the single-grain model dedicated to martensitic transformations developed during the thesis of S. Meftah (2007) is proposed. It consists in introducing the polycrystalline character of the austenite through a process of homogenization based on a self-consistent scheme by calculating the properties of an Equivalent Homogeneous Medium environment (EHM). (author)

  16. The Investigation of Strain-Induced Martensite Reverse Transformation in AISI 304 Austenitic Stainless Steel

    Science.gov (United States)

    Cios, G.; Tokarski, T.; Żywczak, A.; Dziurka, R.; Stępień, M.; Gondek, Ł.; Marciszko, M.; Pawłowski, B.; Wieczerzak, K.; Bała, P.

    2017-10-01

    This paper presents a comprehensive study on the strain-induced martensitic transformation and reversion transformation of the strain-induced martensite in AISI 304 stainless steel using a number of complementary techniques such as dilatometry, calorimetry, magnetometry, and in-situ X-ray diffraction, coupled with high-resolution microstructural transmission Kikuchi diffraction analysis. Tensile deformation was applied at temperatures between room temperature and 213 K (-60 °C) in order to obtain a different volume fraction of strain-induced martensite (up to 70 pct). The volume fraction of the strain-induced martensite, measured by the magnetometric method, was correlated with the total elongation, hardness, and linear thermal expansion coefficient. The thermal expansion coefficient, as well as the hardness of the strain-induced martensitic phase was evaluated. The in-situ thermal treatment experiments showed unusual changes in the kinetics of the reverse transformation (α' → γ). The X-ray diffraction analysis revealed that the reverse transformation may be stress assisted—strains inherited from the martensitic transformation may increase its kinetics at the lower annealing temperature range. More importantly, the transmission Kikuchi diffraction measurements showed that the reverse transformation of the strain-induced martensite proceeds through a displacive, diffusionless mechanism, maintaining the Kurdjumov-Sachs crystallographic relationship between the martensite and the reverted austenite. This finding is in contradiction to the results reported by other researchers for a similar alloy composition.

  17. Towards long lasting zirconia-based composites for dental implants: Transformation induced plasticity and its consequence on ceramic reliability.

    Science.gov (United States)

    Reveron, Helen; Fornabaio, Marta; Palmero, Paola; Fürderer, Tobias; Adolfsson, Erik; Lughi, Vanni; Bonifacio, Alois; Sergo, Valter; Montanaro, Laura; Chevalier, Jérôme

    2017-01-15

    Zirconia-based composites were developed through an innovative processing route able to tune compositional and microstructural features very precisely. Fully-dense ceria-stabilized zirconia ceramics (84vol% Ce-TZP) containing equiaxed alumina (8vol%Al 2 O 3 ) and elongated strontium hexa-aluminate (8vol% SrAl 12 O 19 ) second phases were obtained by conventional sintering. This work deals with the effect of the zirconia stabilization degree (CeO 2 in the range 10.0-11.5mol%) on the transformability and mechanical properties of Ce-TZP-Al 2 O 3 -SrAl 12 O 19 materials. Vickers hardness, biaxial flexural strength and Single-edge V-notched beam tests revealed a strong influence of ceria content on the mechanical properties. Composites with 11.0mol% CeO 2 or above exhibited the classical behaviour of brittle ceramics, with no apparent plasticity and very low strain to failure. On the contrary, composites with 10.5mol% CeO 2 or less showed large transformation-induced plasticity and almost no dispersion in strength data. Materials with 10.5mol% of ceria showed the highest values in terms of biaxial bending strength (up to 1.1GPa) and fracture toughness (>10MPa√m). In these ceramics, as zirconia transformation precedes failure, the Weibull modulus was exceptionally high and reached a value of 60, which is in the range typically reported for metals. The results achieved demonstrate the high potential of using these new strong, tough and stable zirconia-based composites in structural biomedical applications. Yttria-stabilized (Y-TZP) zirconia ceramics are increasingly used for developing metal-free restorations and dental implants. Despite their success related to their excellent mechanical resistance, Y-TZP can undergo Low Temperature Degradation which could be responsible for restoration damage or even worst the failure of the implant. Current research is focusing on strategies to improve the LTD resistance of Y-TZP or to develop alternative composites with better

  18. Dynamic ductile fracture of a central crack

    Science.gov (United States)

    Tsai, Y. M.

    1976-01-01

    A central crack, symmetrically growing at a constant speed in a two dimensional ductile material subject to uniform tension at infinity, is investigated using the integral transform methods. The crack is assumed to be the Dugdale crack, and the finite stress condition at the crack tip is satisfied during the propagation of the crack. Exact expressions of solution are obtained for the finite stress condition at the crack tip, the crack shape, the crack opening displacement, and the energy release rate. All those expressions are written as the product of explicit dimensional quantities and a nondimensional dynamic correction function. The expressions reduce to the associated static results when the crack speed tends to zero, and the nondimensional dynamic correction functions were calculated for various values of the parameter involved.

  19. Modulating factors in the expression of radiation-induced oncogenic transformation

    International Nuclear Information System (INIS)

    Hall, E.J.; Hei, T.K.

    1990-01-01

    Many assays for oncogenic transformation have been developed ranging from those in established rodent cell lines where morphological alteration is scored, to those in human cells growing in nude mice where tumor invasiveness is scored. In general, systems that are most quantitaive are also the least relevant in terms of human carcinogenesis and human risk estimation. The development of cell culture systems has made it possible to assess at the cellular level the oncogenic potential of a variety of chemical, physical and viral agents. Cell culture systems afford the opportunity to identify factors and conditions that may prevent or enhance cellular transformation by radiation and chemicals. Permissive and protective factors in radiation-induced transformation include thyroid hormone and the tumor promoter TPA that increase the transformation incidence for a given dose of radiation, and retinoids, selenium, vitamin E, and 5-aminobenzamide that inhibit the expression of transformation. Densely ionizing α-particles, similar to those emitted by radon daughters, are highly effective in inducing transformations and appear to interact in a supra-additive fashion with asbestos fibers. The activation of a known dominant oncogene has not yet been demonstrated in radiation-induced oncogenic transformation. The most likely mechanism for radiation activation of an oncogene would be via the production of a chromosomal translocation. Radiation also efficiently induces deletions and may thus lead to the loss of a suppressor gene

  20. Experimental study of stress-induced localized transformation plastic zones in tetragonal zirconia polycrystalline ceramics

    International Nuclear Information System (INIS)

    Sun, Q.; Zhao, Z.; Chen, W.; Qing, X.; Xu, X.; Dai, F.

    1994-01-01

    Stress-induced martensitic transformation plastic zones in ceria-stabilized tetragonal zirconia polycrystalline ceramics (Ce-TZP), under loading conditions of uniaxial tension, compression, and three-point bending, are studied by experiments. The transformed monoclinic phase volume fraction distribution and the corresponding plastic strain distribution and the surface morphology (surface uplift) are measured by means of moire interferometry, Raman microprobe spectroscopy, and the surface measurement system. The experimental results from the above three kinds of specimens and methods consistently show that the stress-induced transformation at room temperature of the above specimen is not uniform within the transformation zone and that the plastic deformation is concentrated in some narrow band; i.e., macroscopic plastic flow localization proceeds during the initial stage of plastic deformation. Flow localization phenomena are all observed in uniaxial tension, compression, and three-point bending specimens. Some implications of the flow localization to the constitutive modeling and toughening of transforming thermoelastic polycrystalline ceramics are explored

  1. Pressure-induced ferroelectric to antiferroelectric phase transformation in porous PZT95/5 ceramics

    International Nuclear Information System (INIS)

    Zeng, T.; Dong, X.L.; Chen, X.F.; Yao, C.H.; He, H.L.

    2007-01-01

    The hydrostatic pressure-induced ferroelectric to antiferroelectric (FE-AFE) phase transformation of PZT95/5 ceramics was investigated as a function of porosity, pore shape and pore size. FE-AFE phase transformations were more diffuse and occurred at lower hydrostatic pressures with increasing porosity. The porous PZT95/5 ceramics with spherical pores exhibited higher transformation pressures than those with irregular pores. Moreover, FE-AFE phase transformations of porous PZT95/5 ceramics with polydisperse irregular pores were more diffuse than those of porous PZT95/5 ceramics with monodisperse irregular pores. The relation between pore structure and hydrostatic pressure-induced FE-AFE transformation was established according to stress concentration theory. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Pressure-induced transformations of molecular boron hydride

    International Nuclear Information System (INIS)

    Nakano, Satoshi; Hemley, Russell J; Gregoryanz, Eugene A; Goncharov, Alexander F; Mao, Ho-kwang

    2002-01-01

    Decaborane, a molecular boron hydride, was compressed to 131 GPa at room temperature to explore possible non-molecular phases in this system and their physical properties. Decaborane changed its colour from transparent yellow to orange/red above 50 GPa and then to black above 100 GPa, suggesting some transformations. Raman scattering and infrared (IR) absorption spectroscopy reveal significant structural changes. Above 100 GPa, B-B skeletal, B-H and B-H-B Raman/IR peaks gradually disappeared, which implies a transformation into a non-molecular phase in which conventional borane-type bonding is lost. The optical band gap of the material at 100 GPa was estimated to be about 1.0 eV

  3. Pressure-induced transformations of molecular boron hydride

    CERN Document Server

    Nakano, S; Gregoryanz, E A; Goncharov, A F; Mao Ho Kwang

    2002-01-01

    Decaborane, a molecular boron hydride, was compressed to 131 GPa at room temperature to explore possible non-molecular phases in this system and their physical properties. Decaborane changed its colour from transparent yellow to orange/red above 50 GPa and then to black above 100 GPa, suggesting some transformations. Raman scattering and infrared (IR) absorption spectroscopy reveal significant structural changes. Above 100 GPa, B-B skeletal, B-H and B-H-B Raman/IR peaks gradually disappeared, which implies a transformation into a non-molecular phase in which conventional borane-type bonding is lost. The optical band gap of the material at 100 GPa was estimated to be about 1.0 eV.

  4. GBM secretome induces transient transformation of human neural precursor cells.

    Science.gov (United States)

    Venugopal, Chitra; Wang, X Simon; Manoranjan, Branavan; McFarlane, Nicole; Nolte, Sara; Li, Meredith; Murty, Naresh; Siu, K W Michael; Singh, Sheila K

    2012-09-01

    Glioblastoma (GBM) is the most aggressive primary brain tumor in humans, with a uniformly poor prognosis. The tumor microenvironment is composed of both supportive cellular substrates and exogenous factors. We hypothesize that exogenous factors secreted by brain tumor initiating cells (BTICs) could predispose normal neural precursor cells (NPCs) to transformation. When NPCs are grown in GBM-conditioned media, and designated as "tumor-conditioned NPCs" (tcNPCs), they become highly proliferative and exhibit increased stem cell self-renewal, or the unique ability of stem cells to asymmetrically generate another stem cell and a daughter cell. tcNPCs also show an increased transcript level of stem cell markers such as CD133 and ALDH and growth factor receptors such as VEGFR1, VEGFR2, EGFR and PDGFRα. Media analysis by ELISA of GBM-conditioned media reveals an elevated secretion of growth factors such as EGF, VEGF and PDGF-AA when compared to normal neural stem cell-conditioned media. We also demonstrate that tcNPCs require prolonged or continuous exposure to the GBM secretome in vitro to retain GBM BTIC characteristics. Our in vivo studies reveal that tcNPCs are unable to form tumors, confirming that irreversible transformation events may require sustained or prolonged presence of the GBM secretome. Analysis of GBM-conditioned media by mass spectrometry reveals the presence of secreted proteins Chitinase-3-like 1 (CHI3L1) and H2A histone family member H2AX. Collectively, our data suggest that GBM-secreted factors are capable of transiently altering normal NPCs, although for retention of the transformed phenotype, sustained or prolonged secretome exposure or additional transformation events are likely necessary.

  5. Thermal induced structural transformation of bimetallic AuPd nanoparticles

    International Nuclear Information System (INIS)

    Bruma, A; Li, Z Y

    2014-01-01

    High Angle Annular Dark Field Scanning Transmission Electron Microscope (HAADF-STEM) has been employed for the study of thermal effects of structural transformation of AuPd nanoparticles produced by physical vapour deposition. Depending on the duration of annealing at a temperature of 500 K, atomic resolved imaging analysis reveals the formation of various structure morphologies from the ordered L1 2 superlattice to the core-shell structure. The effects of Pd-oxides are also discussed

  6. Transformation-Induced Creep and Creep Recovery of Shape Memory Alloy.

    Science.gov (United States)

    Takeda, Kohei; Tobushi, Hisaaki; Pieczyska, Elzbieta A

    2012-05-22

    If the shape memory alloy is subjected to the subloop loading under the stress-controlled condition, creep and creep recovery can appear based on the martensitic transformation. In the design of shape memory alloy elements, these deformation properties are important since the deflection of shape memory alloy elements can change under constant stress. The conditions for the progress of the martensitic transformation are discussed based on the kinetics of the martensitic transformation for the shape memory alloy. During loading under constant stress rate, temperature increases due to the stress-induced martensitic transformation. If stress is held constant during the martensitic transformation stage in the loading process, temperature decreases and the condition for the progress of the martensitic transformation is satisfied, resulting in the transformation-induced creep deformation. If stress is held constant during the reverse transformation stage in the unloading process, creep recovery appears due to the reverse transformation. The details for these thermomechanical properties are investigated experimentally for TiNi shape memory alloy, which is most widely used in practical applications. The volume fraction of the martensitic phase increases in proportion to an increase in creep strain.

  7. Inhibition of radiation-induced transformation in vitro by bacterial endotoxins

    International Nuclear Information System (INIS)

    Carew, J.A.; Collins, M.F.; Kennedy, A.R.

    1988-01-01

    Bacterial endotoxins (lipopolysaccharides) were found to suppress X-ray-induced malignant transformation of C3H/10T1/2 cells. Endotoxins were effective if present either throughout the 6-week transformation assay period, or for the final 4-week phase, but not when present only for the initial 2-week phase. Neither growth nor survival of C3H/10T1/2 cells, or a radiation-transformed cell line derived from them, were affected by endotoxins. Also, the endotoxins did not affect the formation of foci by the radiation transformed cells when these cells were co-cultured with untransformed cells. These results suggest that endotoxins exert their effect directly upon the transformation process itself, perhaps at a 'late' step in the conversion of an untransformed to a transformed cell. (author)

  8. Inhibition of radiation-induced transformation in vitro by bacterial endotoxins

    Energy Technology Data Exchange (ETDEWEB)

    Carew, J A; Collins, M F; Kennedy, A R

    1988-05-01

    Bacterial endotoxins (lipopolysaccharides) were found to suppress X-ray-induced malignant transformation of C3H/10T1/2 cells. Endotoxins were effective if present either throughout the 6-week transformation assay period, or for the final 4-week phase, but not when present only for the initial 2-week phase. Neither growth nor survival of C3H/10T1/2 cells, or a radiation-transformed cell line derived from them, were affected by endotoxins. Also, the endotoxins did not affect the formation of foci by the radiation transformed cells when these cells were co-cultured with untransformed cells. These results suggest that endotoxins exert their effect directly upon the transformation process itself, perhaps at a 'late' step in the conversion of an untransformed to a transformed cell.

  9. Cancer Stem-Like Cells Accumulated in Nickel-Induced Malignant Transformation

    Science.gov (United States)

    Wang, Lei; Fan, Jia; Hitron, John Andrew; Son, Young-Ok; Wise, James T.F.; Roy, Ram Vinod; Kim, Donghern; Dai, Jin; Pratheeshkumar, Poyil; Zhang, Zhuo; Shi, Xianglin

    2016-01-01

    Nickel compounds are known as human carcinogens. Chronic environmental exposure to nickel is a worldwide health concern. Although the mechanisms of nickel-induced carcinogenesis are not well understood, recent studies suggest that stem cells/cancer stem cells are likely important targets. This study examines the role of cancer stem cells in nickel-induced cell transformation. The nontransformed human bronchial epithelial cell line (Beas-2B) was chronically exposed to nickel chloride for 12 months to induce cell transformation. Nickel induced Beas-2B cell transformation, and cancer stem-like cells were enriched in nickel-transformed cell (BNiT) population. The BNiT cancer stem-like cells demonstrated enhanced self-renewal and distinctive differentiation properties. In vivo tumorigenesis studies show that BNiT cancer stem-like cells possess a high tumor-initiating capability. It was also demonstrated that superoxide dismutase 1 was involved in the accumulation of cancer stem-like cells; the regulation of superoxide dismutase 1 expression was different in transformed stem-like cells and nontransformed. Overall, the accumulation of stem-like cells and their enhanced stemness functions contribute to nickel-induced tumorigenesis. Our study provides additional insight into the mechanisms by which metals or other chemicals can induce carcinogenesis. PMID:26962057

  10. Micromechanics modelling of ductile fracture

    CERN Document Server

    Chen, Zengtao

    2013-01-01

    This book summarizes research advances in micromechanics modelling of ductile fractures made in the past two decades. The ultimate goal of this book is to reach manufacturing frontline designers and materials engineers by providing a user-oriented, theoretical background of micromechanics modeling. Accordingly, the book is organized in a unique way and presents a vigorous damage percolation model developed by the authors over the last ten years. This model overcomes almost all difficulties of the existing models and can be used to completely accommodate ductile damage development within a single, measured microstructure frame. Related void damage criteria including nucleation, growth and coalescence are then discussed in detail: how they are improved, when and where they are used in the model, and how the model performs in comparison with the existing models. Sample forming simulations are provided to illustrate the model’s performance.

  11. Turbulent breakage of ductile aggregates.

    Science.gov (United States)

    Marchioli, Cristian; Soldati, Alfredo

    2015-05-01

    In this paper we study breakage rate statistics of small colloidal aggregates in nonhomogeneous anisotropic turbulence. We use pseudospectral direct numerical simulation of turbulent channel flow and Lagrangian tracking to follow the motion of the aggregates, modeled as sub-Kolmogorov massless particles. We focus specifically on the effects produced by ductile rupture: This rupture is initially activated when fluctuating hydrodynamic stresses exceed a critical value, σ>σ(cr), and is brought to completion when the energy absorbed by the aggregate meets the critical breakage value. We show that ductile rupture breakage rates are significantly reduced with respect to the case of instantaneous brittle rupture (i.e., breakage occurs as soon as σ>σ(cr)). These discrepancies are due to the different energy values at play as well as to the statistical features of energy distribution in the anisotropic turbulence case examined.

  12. Effects of retained austenite volume fraction, morphology, and carbon content on strength and ductility of nanostructured TRIP-assisted steels

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Y.F., E-mail: shenyf@smm.neu.edu.cn [Key Laboratory for Anisotropy and Texture of Materials (MOE), Northeastern University, 3 Wenhua Road, Shenyang 110004 (China); Qiu, L.N. [Key Laboratory for Anisotropy and Texture of Materials (MOE), Northeastern University, 3 Wenhua Road, Shenyang 110004 (China); Sun, X. [Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352 (United States); Zuo, L. [Key Laboratory for Anisotropy and Texture of Materials (MOE), Northeastern University, 3 Wenhua Road, Shenyang 110004 (China); Liaw, P.K. [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Raabe, D. [Max-Planck-Institut fuer Eisenforschung, Max-Planck-Str. 1, 8, 40237 Düsseldorf (Germany)

    2015-06-11

    With a suite of multi-modal and multi-scale characterization techniques, the present study unambiguously proves that a substantially-improved combination of ultrahigh strength and good ductility can be achieved by tailoring the volume fraction, morphology, and carbon content of the retained austenite (RA) in a transformation-induced-plasticity (TRIP) steel with the nominal chemical composition of 0.19C–0.30Si–1.76Mn–1.52Al (weight percent, wt%). After intercritical annealing and bainitic holding, a combination of ultimate tensile strength (UTS) of 1100 MPa and true strain of 50% has been obtained, as a result of the ultrafine RA lamellae, which are alternately arranged in the bainitic ferrite around junction regions of ferrite grains. For reference, specimens with a blocky RA, prepared without the bainitic holding, yield a low ductility (35%) and a low UTS (800 MPa). The volume fraction, morphology, and carbon content of RA have been characterized using various techniques, including the magnetic probing, scanning electron microscopy (SEM), electron-backscatter-diffraction (EBSD), and transmission electron microscopy (TEM). Interrupted tensile tests, mapped using EBSD in conjunction with the kernel average misorientation (KAM) analysis, reveal that the lamellar RA is the governing microstructure component responsible for the higher mechanical stability, compared to the blocky one. By coupling these various techniques, we quantitatively demonstrate that in addition to the RA volume fraction, its morphology and carbon content are equally important in optimizing the strength and ductility of TRIP-assisted steels.

  13. Mechanical properties of ground state structures in substitutional ordered alloys: High strength, high ductility and high thermal stability

    International Nuclear Information System (INIS)

    Tawancy, H.M.; Aboelfotoh, M.O.

    2014-01-01

    We have studied the effect of atom arrangements in the ground state structures of substitutional ordered alloys on their mechanical properties using nickel–molybdenum-based alloys as model systems. Three alloys with nominal compositions of Ni–19.43 at% Mo, Ni–18.53 at% Mo–15.21 at% Cr and Ni–18.72 at% Mo–6.14 at% Nb are included in the study. In agreement with theoretical predictions, the closely related Pt 2 Mo-type, DO 22 and D1 a superlattices with similar energies are identified by electron diffraction of ground state structures, which can directly be derived from the parent disordered fcc structure by minor atom rearrangements on {420} fcc planes. The three superlattices are observed to coexist during the disorder–order transformation at 700 °C with the most stable superlattice being determined by the exact chemical composition. Although most of the slip systems in the parent disordered fcc structure are suppressed, many of the twinning systems remain operative in the superlattices favoring deformation by twinning, which leads to considerable strengthening while maintaining high ductility levels. Both the Pt 2 Mo-type and DO 22 superlattices are distinguished by high strength and high ductility due to their nanoscale microstructures, which have high thermal stability. However, the D1 a superlattice is found to exhibit poor thermal stability leading to considerable loss of ductility, which has been correlated with self-induced recrystallization by migration of grain boundaries

  14. Pressure-induced phase transformations in L-alanine crystals

    DEFF Research Database (Denmark)

    Olsen, J. Staun; Gerward, Leif; Freire, P.T.C.

    2008-01-01

    Raman scattering and synchrotron X-ray diffraction have been used to investigate the high-pressure behavior of L-alanine. This study has confirmed a structural phase transition observed by Raman scattering at 2.3 GPa and identified it as a change from orthorhombic to tetragonal structure. Another...... phase transformation from tetragonal to monoclinic structure has been observed at about 9 GPa. From the equation of state, the zero-pressure bulk modulus and its pressure derivative have been determined as (31.5 +/- 1.4) GPa and 4.4 +/- 0.4, respectively....

  15. X-radiation-induced transformation in a C3H mouse embryo-derived cell line

    International Nuclear Information System (INIS)

    Terzaghi, M.; Little, J.B.

    1976-01-01

    Reproducible x-ray-induced oncogenic transformation has been demonstrated in an established cell line of mouse embryo fibroblasts. Cells derived from transformed foci formed malignant tumors when injected into syngeneic hosts. An exponential increase in the number of transformants per viable cell occurred with doses of up to 400 rads of x-radiation. The transformation frequency in exponentially growing cultures remained constant at 2.3 x 10 -3 following doses of 400 to 1500 rads. There was little change in survival following x-ray doses up to 300 rads. Doses greater than 300 rads were associated with an exponential decline in survival; the D 0 for the survival curve was 175 rads. Transformation frequency varied with changes in the number of viable cells seeded per dish. There was about a 10-fold decline in the transformation frequency when the number of cells was increased from 400 to 1000 viable cells/100-mm Petri dish. Below this density range there was little change in transformation frequency. The presence of lethally preirradiated cells was not associated with an enhancement of transformation in irradiated cells or with the induction of transformation in unirradiated cell cultures. Amphotericin B (Fungizone) inhibited the appearance of transformants when added to the culture medium within 2 to 3 weeks after initiation of the experiment

  16. Induced over voltage test on transformers using enhanced Z-source inverter based circuit

    Science.gov (United States)

    Peter, Geno; Sherine, Anli

    2017-09-01

    The normal life of a transformer is well above 25 years. The economical operation of the distribution system has its roots in the equipments being used. The economy being such, that it is financially advantageous to replace transformers with more than 15 years of service in the second perennial market. Testing of transformer is required, as its an indication of the extent to which a transformer can comply with the customers specified requirements and the respective standards (IEC 60076-3). In this paper, induced over voltage testing on transformers using enhanced Z source inverter is discussed. Power electronic circuits are now essential for a whole array of industrial electronic products. The bulky motor generator set, which is used to generate the required frequency to conduct the induced over voltage testing of transformers is nowadays replaced by static frequency converter. First conventional Z-source inverter, and second an enhanced Z source inverter is being used to generate the required voltage and frequency to test the transformer for induced over voltage test, and its characteristics is analysed.

  17. The true origin of ductile fracture in aluminium alloys

    OpenAIRE

    Toda, Hiroyuki; Oogo, Hideyuki; Horikawa, Keitaro; Uesugi, Kentaro; Takeuchi, Akihisa; Suzuki, Yasuo; Nakazawa, Mitsuru; Aoki, Yoshimitsu; Kobayashi, Masakazu

    2014-01-01

    It has generally been assumed that metals usually fail as a result of microvoid nucleation induced by particle fracture. Here, we concentrate on high-density micropores filled with hydrogen in aluminum, existence of which has been largely overlooked until quite recently. These micropores exhibit premature growth under external loading, thereby inducing ductile fracture, whereas the particle fracture mechanism operates only incidentally. Conclusive evidence of a micropore mechanism is provided...

  18. Repair mechanisms in radiation-induced cell transformation

    International Nuclear Information System (INIS)

    Elkind, M.M.; Han, A.; Hill, C.K.; Buonaguro, F.

    1983-01-01

    Our data with both low- and high-LET radiations are qualitatively similar to results obtained in vivo. This is evident, for example, in the reductions in cell transformation for protracted exposures of γ-rays. The consistencies between our results with cells and the data of others with animals lend support to Gray's hypothesis that tumorigenesis is the net effect of a low probability inductive process, and a high probability killing process. An important prediction can be made when spontaneous frequency is appreciable (e.g., 43% in the case of reticulum cell sarcoma in RFM mice). For small doses, tumorigenesis would drop provided that: (a) the cells responsible for the spontaneous incidence are present at the time of exposure; and (b) the progenitor cells of the tumor are not resistant to cell killing

  19. Frequency-dependent ultrasound-induced transformation in E. coli.

    Science.gov (United States)

    Deeks, Jeremy; Windmill, James; Agbeze-Onuma, Maduka; Kalin, Robert M; Argondizza, Peter; Knapp, Charles W

    2014-12-01

    Ultrasound-enhanced gene transfer (UEGT) is continuing to gain interest across many disciplines; however, very few studies investigate UEGT efficiency across a range of frequencies. Using a variable frequency generator, UEGT was tested in E. coli at six ultrasonic frequencies. Results indicate frequency can significantly influence UEGT efficiency positively and negatively. A frequency of 61 kHz improved UEGT efficiency by ~70 % higher, but 99 kHz impeded UEGT to an extent worse than no ultrasound exposure. The other four frequencies (26, 133, 174, and 190 kHz) enhanced transformation compared to no ultrasound, but efficiencies did not vary. The influence of frequency on UEGT efficiency was observed across a range of operating frequencies. It is plausible that frequency-dependent dynamics of mechanical and chemical energies released during cavitational-bubble collapse (CBC) are responsible for observed UEGT efficiencies.

  20. Transformer induced instability of the series resonant converter

    Science.gov (United States)

    King, R. J.; Stuart, T. A.

    1983-01-01

    It is shown that the common series resonant power converter is subject to a low frequency oscillation that can lead to the loss of cyclic stability. This oscillation is caused by a low frequency resonant circuit formed by the normal L and C components in series with the magnetizing inductance of the output transformer. Three methods for eliminating this oscillation are presented and analyzed. One of these methods requires a change in the circuit topology during the resonance cycle. This requires a new set of steady state equations which are derived and presented in a normalized form. Experimental results are included which demonstrate the nature of the low frequency oscillation before cyclic stability is lost.

  1. Highly ductile UV-shielding polymer composites with boron nitride nanospheres as fillers.

    Science.gov (United States)

    Fu, Yuqiao; Huang, Yan; Meng, Wenjun; Wang, Zifeng; Bando, Yoshio; Golberg, Dmitri; Tang, Chengchun; Zhi, Chunyi

    2015-03-20

    Polymer composites with enhanced mechanical, thermal or optical performance usually suffer from poor ductility induced by confined mobility of polymer chains. Herein, highly ductile UV-shielding polymer composites are successfully fabricated. Boron nitride (BN) materials, with a wide band gap of around ∼6.0 eV, are used as fillers to achieve the remarkably improved UV-shielding performance of a polymer matrix. In addition, it is found that spherical morphology BN as a filler can keep the excellent ductility of the composites. For a comparison, it is demonstrated that traditional fillers, including conventional BN powders can achieve the similar UV-shielding performance but dramatically decrease the composite ductility. The mechanism behind this phenomenon is believed to be lubricant effects of BN nanospheres for sliding of polymer chains, which is in consistent with the thermal analyses. This study provides a new design to fabricate UV-shielding composite films with well-preserved ductility.

  2. Neutron scattering study of the phase transformation of LaNi3 induced by hydriding

    International Nuclear Information System (INIS)

    Ruan Jinghui; Zeng Xiangxin; Niu Shiwen

    1994-01-01

    The phase transformation of LaNi 3 induced by hydriding and de-hydriding is investigated using the neutron diffraction and the neutron inelastic scattering. The results show that the hydriding sample, LaNi 3 H x , is transformed from crystalline state of the LaNi 3 into amorphous state with a microcrystalline characteristic of LaNi 5 , and the de-hydriding sample produced by LaNi 3 H x dehydrated at 600 degree C is decomposed into new crystalline states composed by LaNi 5 -and La-hydrides. The procedure of phase transformation is that the result of the transformation of LaNi 3 induced by hydriding shows the properties of LaNi 5 -H 2 system

  3. Causal Correlation Functions and Fourier Transforms: Application in Calculating Pressure Induced Shifts

    Science.gov (United States)

    Ma, Q.; Tipping, R. H.; Lavrentieva, N. N.

    2012-01-01

    By adopting a concept from signal processing, instead of starting from the correlation functions which are even, one considers the causal correlation functions whose Fourier transforms become complex. Their real and imaginary parts multiplied by 2 are the Fourier transforms of the original correlations and the subsequent Hilbert transforms, respectively. Thus, by taking this step one can complete the two previously needed transforms. However, to obviate performing the Cauchy principal integrations required in the Hilbert transforms is the greatest advantage. Meanwhile, because the causal correlations are well-bounded within the time domain and band limited in the frequency domain, one can replace their Fourier transforms by the discrete Fourier transforms and the latter can be carried out with the FFT algorithm. This replacement is justified by sampling theory because the Fourier transforms can be derived from the discrete Fourier transforms with the Nyquis rate without any distortions. We apply this method in calculating pressure induced shifts of H2O lines and obtain more reliable values. By comparing the calculated shifts with those in HITRAN 2008 and by screening both of them with the pair identity and the smooth variation rules, one can conclude many of shift values in HITRAN are not correct.

  4. Influence of processing-induced phase transformations on the dissolution of theophylline tablets

    OpenAIRE

    Debnath, Smita; Suryanarayanan, Raj

    2004-01-01

    The object of this investigation was to evaluate the influence of (1) processing-induced decrease in drug crystallinity and (2) phase transformations during dissolution, on the per-formance of theophylline tablet formulations. Anhydrous theophylline underwent multiple transformations (anhydrate »hydrate»anhydrate) during processing. Although the crystallinity of the anhydrate obtained finally was lower than that of the unprocessed drug, it dissolved at a slower rate. This decrease in dissolut...

  5. Deformation-induced phase transformation in 4H–SiC nanopillars

    International Nuclear Information System (INIS)

    Chen, Bin; Wang, Jun; Zhu, Yiwei; Liao, Xiaozhou; Lu, Chunsheng; Mai, Yiu-Wing; Ringer, Simon P.; Ke, Fujiu; Shen, Yaogen

    2014-01-01

    The deformation behaviour of single-crystal SiC nanopillars was studied by a combination of in situ deformation transmission electron microscopy and molecular dynamics simulations. An unexpected deformation-induced phase transformation from the 4H hexagonal structure to the 3C face-centred cubic structure was observed in these nanopillars at room temperature. Atomistic simulations revealed that the 4H to 3C phase transformation follows a stick–slip process with initiation and end stresses of 12.1–14.0 and 7.9–9.0 GPa, respectively. The experimentally measured stress of 9–10 GPa for the phase transformation falls within the range of these theoretical upper and lower stresses. The reasons for the phase transformation are discussed. The finding sheds light on the understanding of phase transformation in polytypic materials at low temperature

  6. Stress-Induced Cubic-to-Hexagonal Phase Transformation in Perovskite Nanothin Films.

    Science.gov (United States)

    Cao, Shi-Gu; Li, Yunsong; Wu, Hong-Hui; Wang, Jie; Huang, Baoling; Zhang, Tong-Yi

    2017-08-09

    The strong coupling between crystal structure and mechanical deformation can stabilize low-symmetry phases from high-symmetry phases or induce novel phase transformation in oxide thin films. Stress-induced structural phase transformation in oxide thin films has drawn more and more attention due to its significant influence on the functionalities of the materials. Here, we discovered experimentally a novel stress-induced cubic-to-hexagonal phase transformation in the perovskite nanothin films of barium titanate (BaTiO 3 ) with a special thermomechanical treatment (TMT), where BaTiO 3 nanothin films under various stresses are annealed at temperature of 575 °C. Both high-resolution transmission electron microscopy and Raman spectroscopy show a higher density of hexagonal phase in the perovskite thin film under higher tensile stress. Both X-ray photoelectron spectroscopy and electron energy loss spectroscopy does not detect any change in the valence state of Ti atoms, thereby excluding the mechanism of oxygen vacancy induced cubic-to-hexagonal (c-to-h) phase transformation. First-principles calculations show that the c-to-h phase transformation can be completed by lattice shear at elevated temperature, which is consistent with the experimental observation. The applied bending plus the residual tensile stress produces shear stress in the nanothin film. The thermal energy at the elevated temperature assists the shear stress to overcome the energy barriers during the c-to-h phase transformation. The stress-induced phase transformation in perovskite nanothin films with TMT provides materials scientists and engineers a novel approach to tailor nano/microstructures and properties of ferroelectric materials.

  7. Chaotic state to self-organized critical state transition of serrated flow dynamics during brittle-to-ductile transition in metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C.; Wang, W. H.; Bai, H. Y., E-mail: hybai@aphy.iphy.ac.cn [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Sun, B. A. [Centre for Advanced Structural Materials, Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Kowloon Tong, Kowloon (Hong Kong)

    2016-02-07

    We study serrated flow dynamics during brittle-to-ductile transition induced by tuning the sample aspect ratio in a Zr-based metallic glass. The statistical analysis reveals that the serrated flow dynamics transforms from a chaotic state characterized by Gaussian-distribution serrations corresponding to stick-slip motion of randomly generated and uncorrelated single shear band and brittle behavior, into a self-organized critical state featured by intermittent scale-free distribution of shear avalanches corresponding to a collective motion of multiple shear bands and ductile behavior. The correlation found between serrated flow dynamics and plastic deformation might shed light on the plastic deformation dynamic and mechanism in metallic glasses.

  8. Numerical simulation of transformation-induced microscopic residual stress in ferrite-martensite lamellar steel

    International Nuclear Information System (INIS)

    Mikami, Y; Inao, A; Mochizuki, M; Toyoda, M

    2009-01-01

    The effect of transformation-induced microscopic residual stress on fatigue crack propagation behavior of ferrite-martensite lamellar steel was discussed. Fatigue tests of prestrained and non-prestrained specimens were performed. Inflections and branches at ferrite-martensite boundaries were observed in the non-prestrained specimens. On the other hand, less inflections and branches were found in the prestrained specimens. The experimental results showed that the transformation induced microscopic residual stress has influence on the fatigue crack propagation behavior. To estimate the microscopic residual, a numerical simulation method for the calculation of microscopic residual stress stress induced by martensitic transformation was performed. The simulation showed that compressive residual stress was generated in martensite layer, and the result agree with the experimental result that inflections and branches were observed at ferrite-martensite boundaries.

  9. Elimination of the induced current error in magnetometers using superconducting flux transformers

    International Nuclear Information System (INIS)

    Dummer, D.; Weyhmann, W.

    1987-01-01

    The changing magnetization of a sample in a superconducting flux transformer coupled magnetometer induces a current in the transformer which in turn changes the field at the sample. This ''image'' field and the error caused by it can be eliminated by sensing the current in the loop and nulling it by feedback through a mutual inductance. We have tested the technique on the superconducting transition of indium in an applied magnetic field and shown that the observed width of the transition is greatly reduced by maintaining zero current in the flux transformer

  10. Deformation Induced Martensitic Transformation and Its Initial Microstructure Dependence in a High Alloyed Duplex Stainless Steel

    DEFF Research Database (Denmark)

    Xie, Lin; Huang, Tian Lin; Wang, Yu Hui

    2017-01-01

    Deformation induced martensitic transformation (DIMT) usually occurs in metastable austenitic stainless steels. Recent studies have shown that DIMT may occur in the austenite phase of low alloyed duplex stainless steels. The present study demonstrates that DIMT can also take place in a high alloyed...... Fe–23Cr–8.5Ni duplex stainless steel, which exhibits an unexpectedly rapid transformation from γ-austenite into α′-martensite. However, an inhibited martensitic transformation has been observed by varying the initial microstructure from a coarse alternating austenite and ferrite band structure...

  11. Pressure-induced phase transformation of HfO2

    International Nuclear Information System (INIS)

    Arashi, H.

    1992-01-01

    This paper reports on the pressure dependence of the Raman spectra of HfO 2 that was measured by a micro-Raman technique using a single-crystal specimen in the pressure range from 0 to 10 GPa at room temperature. The symmetry assignment of Raman bands of the monoclinic phase was experimentally accomplished from the polarization measurements for the single crystal. With increased pressure, a phase transformation for the monoclinic phase took place at 4.3 ± 0.3 GPa. Nineteen Raman bands were observed for the high-pressure phase. The spectral structure of the Raman bands for the high-pressure phase was similar with those reported previously for ZrO 2 . The space group for the high pressure phase of HfO 2 was determined as Pbcm, which was the same as that of the high-pressure phase for ZrO 2 on the basis of the number and the spectral structure of the Raman bands

  12. Stress-induced martensitic transformation and ferroelastic deformation adjacent microhardness indents in tetragonal zirconia single crystals

    International Nuclear Information System (INIS)

    Chien, F.R.; Ubic, F.J.; Prakash, V.; Heuer, A.H.

    1998-01-01

    The stress-induced tetragonal to monoclinic (t → m) martensitic transformation, stress-induced ferroelastic domain switching, and dislocation slip were induced by Vickers microindentation at elevated temperatures in polydomain single crystals of 3 mol%-Y 2 O 3 -stabilized tetragonal ZrO 2 single crystals (3Y-TZS). Chemical etching revealed traces along t directions adjacent to indentations, and Raman spectroscopy and TEM have shown that these traces are caused by products of the martensitic transformation, i.e. the monoclinic product phase forms primarily as thin, long plates with a habit plane approximately on (bar 301) m . This habit plane and the associated shear strain arising from the transformation, visible in TEM micrographs at the intersection of crystallographically equivalent martensite plates, were successfully predicted using the observed lattice correspondence and the phenomenological invariant plane strain theory of martensitic transformations. The extent of the martensitic transformation increased with increasing temperature from room temperature up to 300 C, but then decreased at higher temperatures. Ferroelastic deformation of tetragonal ZrO 2 has been observed at all temperatures up to 1,000 C. At the highest temperature, only ferroelastic domain switching and dislocation slip occurred during indentation-induced deformation

  13. Electron backscatter diffraction studies of focused ion beam induced phase transformation in cobalt

    Energy Technology Data Exchange (ETDEWEB)

    Jones, H.G., E-mail: helen.jones@npl.co.uk [National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW (United Kingdom); Day, A.P. [Aunt Daisy Scientific Ltd, Claremont House, High St, Lydney GL15 5DX (United Kingdom); Cox, D.C. [National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW (United Kingdom); Advanced Technology Institute, University of Surrey, Guildford GU2 7XH (United Kingdom)

    2016-10-15

    A focused ion beam microscope was used to induce cubic to hexagonal phase transformation in a cobalt alloy, of similar composition to that of the binder phase in a hardmetal, in a controlled manner at 0°, 45° and 80° ion incident angles. The cobalt had an average grain size of ~ 20 μm, allowing multiple orientations to be studied, exposed to a range of doses between 6 × 10{sup 7} and 2 × 10{sup 10} ions/μm{sup 2}. Electron backscatter diffraction (EBSD) was used to determine the original and induced phase orientations, and area fractions, before and after the ion beam exposure. On average, less phase transformation was observed at higher incident angles and after lower ion doses. However there was an orientation effect where grains with an orientation close to (111) planes were most susceptible to phase transformation, and (101) the least, where grains partially and fully transformed at varying ion doses. - Highlights: •Ion-induced phase change in FCC cobalt was observed at multiple incidence angles. •EBSD was used to study the relationship between grain orientation and transformation. •Custom software analysed ion dose and phase change with respect to grain orientation. •A predictive capability of ion-induced phase change in cobalt was enabled.

  14. From brittle to ductile: a structure dependent ductility of diamond nanothread.

    Science.gov (United States)

    Zhan, Haifei; Zhang, Gang; Tan, Vincent B C; Cheng, Yuan; Bell, John M; Zhang, Yong-Wei; Gu, Yuantong

    2016-06-07

    As a potential building block for the next generation of devices/multifunctional materials that are spreading in almost every technology sector, one-dimensional (1D) carbon nanomaterial has received intensive research interests. Recently, a new ultra-thin diamond nanothread (DNT) has joined this palette, which is a 1D structure with poly-benzene sections connected by Stone-Wales (SW) transformation defects. Using large-scale molecular dynamics simulations, we found that this sp(3) bonded DNT can transition from brittle to ductile behaviour by varying the length of the poly-benzene sections, suggesting that DNT possesses entirely different mechanical responses than other 1D carbon allotropes. Analogously, the SW defects behave like a grain boundary that interrupts the consistency of the poly-benzene sections. For a DNT with a fixed length, the yield strength fluctuates in the vicinity of a certain value and is independent of the "grain size". On the other hand, both yield strength and yield strain show a clear dependence on the total length of DNT, which is due to the fact that the failure of the DNT is dominated by the SW defects. Its highly tunable ductility together with its ultra-light density and high Young's modulus makes diamond nanothread ideal for the creation of extremely strong three-dimensional nano-architectures.

  15. Investigation of strain-induced martensitic transformation in metastable austenite using nanoindentation

    International Nuclear Information System (INIS)

    Ahn, T.-H.; Oh, C.-S.; Kim, D.H.; Oh, K.H.; Bei, H.; George, E.P.; Han, H.N.

    2010-01-01

    Strain-induced martensitic transformation of metastable austenite was investigated by nanoindentation of individual austenite grains in multi-phase steel. A cross-section prepared through one of these indented regions using focused ion beam milling was examined by transmission electron microscopy. The presence of martensite underneath the indent indicates that the pop-ins observed on the load-displacement curve during nanoindentation correspond to the onset of strain-induced martensitic transformation. The pop-ins can be understood as resulting from the selection of a favorable martensite variant during nanoindentation.

  16. Investigation of Strain-Induced Martensitic Transformation in Metastable Austenite using Nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, T.-H. [Seoul National University; Oh, C.-S. [Korean Institute of Materials Science; Kim, D. H. [Seoul National University; Oh, K. H. [Seoul National University; Bei, Hongbin [ORNL; George, Easo P [ORNL; Han, H. N. [Seoul National University

    2010-01-01

    Strain-induced martensitic transformation of metastable austenite was investigated by nanoindentation of individual austenite grains in multi-phase steel. A cross-section prepared through one of these indented regions using focused ion beam milling was examined by transmission electron microscopy. The presence of martensite underneath the indent indicates that the pop-ins observed on the load-displacement curve during nanoindentation correspond to the onset of strain-induced martensitic transformation. The pop-ins can be understood as resulting from the selection of a favorable martensite variant during nanoindentation.

  17. Beyond the Numbers: Understanding the Transformation Induced by INDCs

    International Nuclear Information System (INIS)

    Spencer, Thomas; Pierfederici, Roberta; Waisman, Henri; Colombier, Michel; Bertram, Christoph; Kriegler, Elmar; Luderer, Gunnar; Humpenoeder, Florian; Popp, Alexander; Edenhofer, Ottmar; Den Elzen, Michel; Van Vuuren, Detlef; Van Soest, Heleen; Paroussos, Leonidas; Fragkos, Panagiotis; Kainuma, Mikiko; Masui, Toshihiko; Oshiro, Ken; Akimoto, Keigo; Shoai Tehrani, Bianka; Sano, Fuminori; Oda, Junichiro; Clarke, Leon; Iyer, Gokul; Edmonds, Jae; TENG, Fei; FU, Sha; Kejun, Jiang; Koeberle, Alexandre C.; Szklo, Alexandre; Lucena, Andre F.P.; Portugal-Pereira, Joana; Rochedo, Pedro; Schaeffer, Roberto; Awasthy, Aayushi; Kumar Shrivastava, Manish; Mathur, Ritu; Rogelj, Joeri; Jewell, Jessica; Riahi, Keywan; Garg, Amit

    2015-10-01

    The present analysis of the contributions (INDCs) submitted by Member States to the United Nations Framework Convention on Climate Change (UNFCCC) in the run-up to COP21 was conducted by leading research teams from Brazil, China, Japan, India, the United States and the European Union within the MILES Project (funded by the European Commission). By investigating the concrete implications of INDCs for the low-carbon transformation by and beyond 2030, from energy systems, buildings to transport and industry, this study complements the upcoming cutting-edge assessments by UNFCCC and UNEP of the impact of INDCs on global emissions and the global temperature goal. The 'Modelling and Informing Low-Emission Strategies' (MILES) project is an international research project bringing together 16 leading research teams in order to build capacity and knowledge on low-emissions development strategies. The objective of this report is to understand the implications of INDCs of the 5 countries and 1 region covered by the project (US, China, Japan, EU, Brazil and India), both at a national and global level, by investigating the concrete implications of INDCs for the low-carbon transformation by and beyond 2030, from energy systems, buildings to transport and industry. A significant transition appears in the electricity sector, where INDCs will further drive the transition towards renewables and other low-emissions forms of electricity production. In the six major economies assessed individually, carbon dioxide emissions per unit of electricity production falls by about 40% between 2010 and 2030 and renewable electricity becomes the dominant source of electricity production at about 36% of the electricity mix. Some crucial low-carbon solutions, like CCS, electric vehicles, advanced biofuels, sustainable urban planning, appear unlikely to be developed under the INDCs at the scale and speed required for a 2 deg. C scenario. Likewise, the report highlights that INDCs would leave too much

  18. Ligand induced shape transformation of thorium dioxide nanocrystals.

    Science.gov (United States)

    Wang, Gaoxue; Batista, Enrique R; Yang, Ping

    2018-04-27

    Nanocrystals (NCs) with size and shape dependent properties are a thriving research field. Remarkable progress has been made in the controlled synthesis of NCs of stable elements in the past two decades; however, the knowledge of the NCs of actinide compounds has been considerably limited due the difficulties in handling them both experimentally and theoretically. Actinide compounds, especially actinide oxides, play a critical role in many stages of the nuclear fuel cycle. Recently, a non-aqueous surfactant assisted approach has been developed for the synthesis of actinide oxide NCs with different morphologies, but an understanding of its control factors is still missing to date. Herein we present a comprehensive study on the low index surfaces of thorium dioxide (ThO2) and their interactions with relevant surfactant ligands using density functional calculations. A systematic picture on the thermodynamic stability of ThO2 NCs of different sizes and shapes is obtained employing empirical models based on the calculated surface energies. It is found that bare ThO2 NCs prefer the octahedral shape terminated by (111) surfaces. Oleic acid displays selective adsorption on the (110) surface, leading to the shape transformation from octahedrons to nanorods. Other ligands such as acetylacetone, oleylamine, and trioctylphosphine oxide do not modify the equilibrium shape of ThO2 NCs. This work provides atomic level insights into the anisotropic growth of ThO2 NCs that was recently observed in experiments, and thus may contribute to the controlled synthesis of actinide oxide NCs with well-defined size and shape for future applications.

  19. Radiation-induced phase transformation in ferromagnetic perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Podsekin, A K; Dem' yanov, V V; Ivanova, V V; Venevtsev, Yu N [Nauchno-Issledovatel' skij Fiziko-Khimicheskij Inst., Moscow (USSR)

    1976-12-01

    An effect of neutron irradiation inducing a phase transition in ferromagnetic perovskite, Sr/sub 0.3/La/sub 0.7/MnO/sub 3/, has been discovered and studied. It is shown that a change in the Curie temperature is proportional to the dose of reactor irradiation. A decrease in the temperature of the phase transition with the concentration of radiation defects is accompanied by an increase in the electrical specific resistance and a change in the initial lattice parameters. It is shown that the radiation shift is due to at least two causes, viz. to an increase in the parameters of the elementary cell and the growth of the electrical specific resistance as a result of bounded electron states' forming on the radiation defects.

  20. Computer model for ductile fracture

    International Nuclear Information System (INIS)

    Moran, B.; Reaugh, J. E.

    1979-01-01

    A computer model is described for predicting ductile fracture initiation and propagation. The computer fracture model is calibrated by simple and notched round-bar tension tests and a precracked compact tension test. The model is used to predict fracture initiation and propagation in a Charpy specimen and compare the results with experiments. The calibrated model provides a correlation between Charpy V-notch (CVN) fracture energy and any measure of fracture toughness, such as J/sub Ic/. A second simpler empirical correlation was obtained using the energy to initiate fracture in the Charpy specimen rather than total energy CVN, and compared the results with the empirical correlation of Rolfe and Novak

  1. Inhibition and reversal of nickel-induced transformation by the histone deacetylase inhibitor trichostatin A

    International Nuclear Information System (INIS)

    Zhang Qunwei; Salnikow, Konstantin; Kluz, Thomas; Chen, L.C.; Su, W.C.; Costa, Max

    2003-01-01

    The carcinogenic process initiated by nongenotoxic carcinogens involves modulation of gene expression. Nickel compounds have low mutagenic activity, but are highly carcinogenic. In vitro both mouse and human cells can be efficiently transformed by soluble and insoluble nickel compounds to anchorage-independent growth. Because previous studies have shown that carcinogenic nickel compounds silence genes by inhibiting histone acetylation and enhancing DNA methylation, we investigated the effect of enhancing histone acetylation on cell transformation. The exposure of nickel-transformed cells to the histone deacetylase inhibitor trichostatin A (TSA) resulted in the appearance of significant number of revertants measured by their inability to grow in soft agar. Using the Affymetrix GeneChip we found that the level of expression of a significant number of genes was changed (suppressed or upregulated) in nickel-transformed clones but returned to a normal level in revertants obtained following TSA treatment. Moreover, we found that treatment of cells with TSA inhibited the ability of nickel to transform mouse PW cells to anchorage-independent growth. Treatment with TSA also inhibited the ability of nickel to transform human HOS cells, although to a lesser extent. In contrast, treatment with TSA was not able to revert established cancer cell lines as readily as the nickel-transformed cells. These data indicated that modulation of gene expression is important for nickel-induced transformation

  2. Strong, Ductile, and Thermally Stable bcc-Mg Nanolaminates.

    Science.gov (United States)

    Pathak, Siddhartha; Velisavljevic, Nenad; Baldwin, J Kevin; Jain, Manish; Zheng, Shijian; Mara, Nathan A; Beyerlein, Irene J

    2017-08-15

    Magnesium has attracted attention worldwide because it is the lightest structural metal. However, a high strength-to-weight ratio remains its only attribute, since an intrinsic lack of strength, ductility and low melting temperature severely restricts practical applications of Mg. Through interface strains, the crystal structure of Mg can be transformed and stabilized from a simple hexagonal (hexagonal close packed hcp) to body center cubic (bcc) crystal structure at ambient pressures. We demonstrate that when introduced into a nanocomposite bcc Mg is far more ductile, 50% stronger, and retains its strength after extended exposure to 200 C, which is 0.5 times its homologous temperature. These findings reveal an alternative solution to obtaining lightweight metals critically needed for future energy efficiency and fuel savings.

  3. Influence of creep ductility on creep-fatigue behaviour of 20%Cr/25%Ni/Nb stainless steel

    International Nuclear Information System (INIS)

    Gladwin, D.; Miller, D.A.

    1985-01-01

    The influence of creep ductility on creep-fatigue endurance of 20%Cr/25%Ni/Nb stainless steel has been examined. In order to induce different creep ductilities in the 20/25/Nb stainless steel, three different thermo-mechanical routes were employed. These resulted in a range of ductilities (3-36%) being obtained at the strain rates of interest. Strain controlled slow-fast creep-fatigue cycles were used with strain rates of 10 -6 s -1 , 10 -7 s -1 in tension and 10 -3 s -1 in compression. It was found that creep ductility strongly influenced the creep-fatigue endurance of the 20/25/Nb stainless steel. When failure was creep dominated endurance was found to be directly proportional to the creep ductility. A ductility exhaustion model has been used to successfully predict creep-fatigue endurance when failure was creep dominated. (author)

  4. Photostress analysis of stress-induced martensite phase transformation in superelastic NiTi

    International Nuclear Information System (INIS)

    Katanchi, B.; Choupani, N.; Khalil-Allafi, J.; Baghani, M.

    2017-01-01

    Phase transformation in shape memory alloys is the most important factor in their unique behavior. In this paper, the formation of stress induced martensite phase transformation in a superelastic NiTi (50.8% Ni) shape memory alloy was investigated by using the photo-stress method. First, the material's fabrication procedure has been described and then the material was studied using the metallurgical tests such as differential scanning calorimetry and X-ray diffraction to characterize the material features and the mechanical tensile test to investigate the superelastic behavior. As a new method in observation of the phase transformation, photo-stress pictures showed the formation of stress induced martensite in a superelastic dog-bone specimen during loading and subsequently it's disappearing during unloading. Finally, finite element analysis was implemented using the constitutive equations derived based on the Boyd-Lagoudas phenomenological model.

  5. Photostress analysis of stress-induced martensite phase transformation in superelastic NiTi

    Energy Technology Data Exchange (ETDEWEB)

    Katanchi, B. [Mechanical Engineering Faculty, Sahand University of Technology, Tabriz (Iran, Islamic Republic of); Choupani, N., E-mail: choupani@sut.ac.ir [Mechanical Engineering Faculty, Sahand University of Technology, Tabriz (Iran, Islamic Republic of); Khalil-Allafi, J. [Research Center for Advance Materials, Faculty of Materials Engineering, Sahand University of Technology, Tabriz (Iran, Islamic Republic of); Baghani, M. [School of Mechanical Engineering, College of Engineering, University of Tehran (Iran, Islamic Republic of)

    2017-03-14

    Phase transformation in shape memory alloys is the most important factor in their unique behavior. In this paper, the formation of stress induced martensite phase transformation in a superelastic NiTi (50.8% Ni) shape memory alloy was investigated by using the photo-stress method. First, the material's fabrication procedure has been described and then the material was studied using the metallurgical tests such as differential scanning calorimetry and X-ray diffraction to characterize the material features and the mechanical tensile test to investigate the superelastic behavior. As a new method in observation of the phase transformation, photo-stress pictures showed the formation of stress induced martensite in a superelastic dog-bone specimen during loading and subsequently it's disappearing during unloading. Finally, finite element analysis was implemented using the constitutive equations derived based on the Boyd-Lagoudas phenomenological model.

  6. Constitutive modelling of stainless steels for cryogenic applications. Strain induced martensitic transformation

    CERN Document Server

    Garion, C

    2001-01-01

    The 300-series stainless steels are metastable austenitic alloys: martensitic transformation occurs at low temperatures and/or when plastic strain fields develop in the structures. The transformation influences the mechanical properties of the material. The present note aims at proposing a set of constitutive equations describing the plastic strain induced martensitic transformation in the stainless steels at cryogenic temperatures. The constitutive modelling shall create a bridge between the material sciences and the structural analysis. For the structures developing and accumulating plastic deformations at sub-zero temperatures, it is of primary importance to be able to predict the intensity of martensitic transformation and its effect on the material properties. In particular, the constitutive model has been applied to predict the behaviour of the components of the LHC interconnections, the so-called bellows expansion joints (the LHC mechanical compensation system).

  7. Advances in improvement of stress tolerance by induced mutation and genetic transformation in alfalfa

    International Nuclear Information System (INIS)

    Huang Xin; Ye Hongxia; Shu Xiaoli; Wu Dianxing

    2008-01-01

    In order to provide references for stress-tolerant breeding of alfalfa, genetic basis of stress-tolerant traits was briefly introduced and advanced in improvement of stress-tolerance by induced mutation and genetic transformation in alfalfa were reviewed. (authors)

  8. Radiation-induced irreparable heritable changes in cells promoting their tumoral transformation

    International Nuclear Information System (INIS)

    Kuzin, A.M.; Vagabova, M.Eh.; Yurov, S.S.

    1988-01-01

    In experiments with model plant tumors (Kalanchoe-ti plasmid Agrobat. tumefaciens C-58D) it was shown that exposure of the recepient plant to low-level γ-radiation of Gy induced changes in cells that were not repaired over two months promoting tumoral transformations in them. Those changes were shown to persist in the offspring of the exposed somatic cells

  9. Shear-induced structural transformation and plasticity in ultraincompressible ReB2 limit its hardness

    Czech Academy of Sciences Publication Activity Database

    Zhang, R. F.; Legut, Dominik; Niewa, R.; Argon, A. S.; Veprek, S.

    2010-01-01

    Roč. 82, č. 10 (2010), 104104/1-104104/7 ISSN 1098-0121 Institutional research plan: CEZ:AV0Z20410507 Keywords : ReB2 * ab initio * ultrahard * shear-induced transformation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.772, year: 2010

  10. Stress induced martensitic transformation from bcc to fcc in Ag-Zn

    International Nuclear Information System (INIS)

    Takezawa, K.; Akamatsu, R.; Marukawa, K.

    1995-01-01

    The martensitic transformation in Ag-Zn alloys of low-Zn content has been studied by optical and electron microscopic observations and by tensile tests. The β 1 phase of B2 structure transforms to the thermo-elastic martensite having 9R structure similar to Cu-based alloys upon cooling to temperature below Ms. When the β 1 phase is stretched at room temperature, the slip deformation occurs at first and then the stress-induced martensite(SIM) of wedge-like morphology forms. The SIM has the ordered fcc structure containing micro-twins. This direct transformation from bcc to fcc is a unique feature in Ag-Zn alloys. In Cu alloys, martensites of fcc structure appear only after the second transformation from the first transformation product of 9R structure. The critical stress for the martensitic transformation and a degree of order of SIM decrease as the deformation temperature rises. In Ag-Zn alloys, the martensite of disordered fcc is thermally produced also by up-quenching to a higher temperature. In the present study, the relation between martensites of ordered and disordered fcc is discussed through thermodynamical calculations. The condition for the direct transformation from bcc to fcc is also examined. (orig.)

  11. Stress induced transformation to bainite in Fe-Cr-Mo-C pressure vessel steel

    International Nuclear Information System (INIS)

    Bhadeshia, H.K.D.H.; David, S.A.; Vitek, J.M.; Reed, R.W.

    1991-01-01

    The kinetics of the bainitic transformation in a polycrystalline Fe-Cr-Mo-C alloy designed for applications in energy generation systems has been studied, with particular attention to the influence of mild tensile stresses on transformation behaviour. The steel was found to exhibit the incomplete reaction phenomenon, in which transformation to bainite stops well before the residual austenite acquires its paraequilibrium carbon concentration. It was found that even in the absence of an applied stress, the growth of bainitic ferrite caused anisotropic changes in specimen dimensions, consistent with the existence of crystallographic texture in its austenitic condition and, significantly, with the nature of the invariant-plane strain shape change that accompanies the growth of bainitic ferrite. Thus, transformation induced plasticity could be detected in fine grained polycrystalline samples, even in the absence of applied stress. The application of an external stress was found to alter radically the transformation behaviour, with clear evidence that the stress tends to favour the development of certain crystallographic variants of bainite, even though the stress may be well below the single phase yield strength. It is concluded that the transformation is influenced significantly by stresses as low as 45 MN m -2 , even though the effect may not be obvious in metallographic studies. The results are analysed and discussed in terms of the mechanism of the bainite transformation. (author)

  12. Mitochondrial clearance by the STK38 kinase supports oncogenic Ras-induced cell transformation

    Science.gov (United States)

    Bettoun, Audrey; Surdez, Didier; Vallerand, David; Gundogdu, Ramazan; Sharif, Ahmad A.D.; Gomez, Marta; Cascone, Ilaria; Meunier, Brigitte; White, Michael A.; Codogno, Patrice; Parrini, Maria Carla; Camonis, Jacques H.; Hergovich, Alexander

    2016-01-01

    Oncogenic Ras signalling occurs frequently in many human cancers. However, no effective targeted therapies are currently available to treat patients suffering from Ras-driven tumours. Therefore, it is imperative to identify downstream effectors of Ras signalling that potentially represent promising new therapeutic options. Particularly, considering that autophagy inhibition can impair the survival of Ras-transformed cells in tissue culture and mouse models, an understanding of factors regulating the balance between autophagy and apoptosis in Ras-transformed human cells is needed. Here, we report critical roles of the STK38 protein kinase in oncogenic Ras transformation. STK38 knockdown impaired anoikis resistance, anchorage-independent soft agar growth, and in vivo xenograft growth of Ras-transformed human cells. Mechanistically, STK38 supports Ras-driven transformation through promoting detachment-induced autophagy. Even more importantly, upon cell detachment STK38 is required to sustain the removal of damaged mitochondria by mitophagy, a selective autophagic process, to prevent excessive mitochondrial reactive oxygen species production that can negatively affect cancer cell survival. Significantly, knockdown of PINK1 or Parkin, two positive regulators of mitophagy, also impaired anoikis resistance and anchorage-independent growth of Ras-transformed human cells, while knockdown of USP30, a negative regulator of PINK1/Parkin-mediated mitophagy, restored anchorage-independent growth of STK38-depleted Ras-transformed human cells. Therefore, our findings collectively reveal novel molecular players that determine whether Ras-transformed human cells die or survive upon cell detachment, which potentially could be exploited for the development of novel strategies to target Ras-transformed cells. PMID:27283898

  13. Room-temperature ductile inorganic semiconductor

    Science.gov (United States)

    Shi, Xun; Chen, Hongyi; Hao, Feng; Liu, Ruiheng; Wang, Tuo; Qiu, Pengfei; Burkhardt, Ulrich; Grin, Yuri; Chen, Lidong

    2018-05-01

    Ductility is common in metals and metal-based alloys, but is rarely observed in inorganic semiconductors and ceramic insulators. In particular, room-temperature ductile inorganic semiconductors were not known until now. Here, we report an inorganic α-Ag2S semiconductor that exhibits extraordinary metal-like ductility with high plastic deformation strains at room temperature. Analysis of the chemical bonding reveals systems of planes with relatively weak atomic interactions in the crystal structure. In combination with irregularly distributed silver-silver and sulfur-silver bonds due to the silver diffusion, they suppress the cleavage of the material, and thus result in unprecedented ductility. This work opens up the possibility of searching for ductile inorganic semiconductors/ceramics for flexible electronic devices.

  14. Finite-strain micromechanical model of stress-induced martensitic transformations in shape memory alloys

    International Nuclear Information System (INIS)

    Stupkiewicz, S.; Petryk, H.

    2006-01-01

    A micromechanical model of stress-induced martensitic transformation in single crystals of shape memory alloys is developed. This model is a finite-strain counterpart to the approach presented recently in the small-strain setting [S. Stupkiewicz, H. Petryk, J. Mech. Phys. Solids 50 (2002) 2303-2331]. The stress-induced transformation is assumed to proceed by the formation and growth of parallel martensite plates within the austenite matrix. Propagation of phase transformation fronts is governed by a rate-independent thermodynamic criterion with a threshold value for the thermodynamic driving force, including in this way the intrinsic dissipation due to phase transition. This criterion selects the initial microstructure at the onset of transformation and governs the evolution of the laminated microstructure at the macroscopic level. A multiplicative decomposition of the deformation gradient into elastic and transformation parts is assumed, with full account for the elastic anisotropy of the phases. The pseudoelastic behavior of Cu-Zn-Al single crystal in tension and compression is studied as an application of the model

  15. Computer simulation of ductile fracture

    International Nuclear Information System (INIS)

    Wilkins, M.L.; Streit, R.D.

    1979-01-01

    Finite difference computer simulation programs are capable of very accurate solutions to problems in plasticity with large deformations and rotation. This opens the possibility of developing models of ductile fracture by correlating experiments with equivalent computer simulations. Selected experiments were done to emphasize different aspects of the model. A difficult problem is the establishment of a fracture-size effect. This paper is a study of the strain field around notched tensile specimens of aluminum 6061-T651. A series of geometrically scaled specimens are tested to fracture. The scaled experiments are conducted for different notch radius-to-diameter ratios. The strains at fracture are determined from computer simulations. An estimate is made of the fracture-size effect

  16. Ductile failure X-prize.

    Energy Technology Data Exchange (ETDEWEB)

    Cox, James V.; Wellman, Gerald William; Emery, John M.; Ostien, Jakob T.; Foster, John T.; Cordova, Theresa Elena; Crenshaw, Thomas B.; Mota, Alejandro; Bishop, Joseph E.; Silling, Stewart Andrew; Littlewood, David John; Foulk, James W., III; Dowding, Kevin J.; Dion, Kristin; Boyce, Brad Lee; Robbins, Joshua H.; Spencer, Benjamin Whiting

    2011-09-01

    Fracture or tearing of ductile metals is a pervasive engineering concern, yet accurate prediction of the critical conditions of fracture remains elusive. Sandia National Laboratories has been developing and implementing several new modeling methodologies to address problems in fracture, including both new physical models and new numerical schemes. The present study provides a double-blind quantitative assessment of several computational capabilities including tearing parameters embedded in a conventional finite element code, localization elements, extended finite elements (XFEM), and peridynamics. For this assessment, each of four teams reported blind predictions for three challenge problems spanning crack initiation and crack propagation. After predictions had been reported, the predictions were compared to experimentally observed behavior. The metal alloys for these three problems were aluminum alloy 2024-T3 and precipitation hardened stainless steel PH13-8Mo H950. The predictive accuracies of the various methods are demonstrated, and the potential sources of error are discussed.

  17. Energetic approach for ductile tearing

    International Nuclear Information System (INIS)

    Marie, St.

    1999-01-01

    This study focuses on ductile crack initiation and propagation. It aims to propose an approach for the engineer allowing the prediction of the evolution of cracks in large scale components, from parameters determined on laboratory specimens. A crack initiation criterion, defining a J i tenacity related to crack tip blunting proposed in the literature is validated in the study. This criterion is shown to be transferable from laboratory specimens to structures. The literature review shows that an approach based on the dissipated energy in the fracture process during propagation offers an economical and simple solution to simulate large crack growth. A numerical method is proposed to estimate this fracture energy. The existence of an energy parameter G fr is shown, by simulating the propagation by the simultaneous release of several elements and by the use of the Rice integral with an original integration path. This parameter represents the needed energy for a unit crack extension and appears to be intrinsic to the material. A global energy statement allows to relate this parameter to a variation of the plastic part of J integral. It offers a second numerical method to simulate the propagation just from stationary numerical calculations, as well as the elaboration of a simplified method. This approach, using two parameters J i and G fr , intrinsic to the material and experimentally measurable on specimens, is validated on many tests such as crack pipes subjected to four points bending and cracked rings in compression. For example, this approach allows to model up to 90 mm ductile tearing in a pipe with a circumferential through-wall crack in ferritic steel, or to anticipate the evolution of a semi-elliptical crack in an aged austenitic ferritic steel plate subjected to bending. (author)

  18. Prediction of lung cells oncogenic transformation for induced radon progeny alpha particles using sugarscape cellular automata.

    Science.gov (United States)

    Baradaran, Samaneh; Maleknasr, Niaz; Setayeshi, Saeed; Akbari, Mohammad Esmaeil

    2014-01-01

    Alpha particle irradiation from radon progeny is one of the major natural sources of effective dose in the public population. Oncogenic transformation is a biological effectiveness of radon progeny alpha particle hits. The biological effects which has caused by exposure to radon, were the main result of a complex series of physical, chemical, biological and physiological interactions. The cellular and molecular mechanisms for radon-induced carcinogenesis have not been clear yet. Various biological models, including cultured cells and animals, have been found useful for studying the carcinogenesis effects of radon progeny alpha particles. In this paper, sugars cape cellular automata have been presented for computational study of complex biological effect of radon progeny alpha particles in lung bronchial airways. The model has included mechanism of DNA damage, which has been induced alpha particles hits, and then formation of transformation in the lung cells. Biomarkers were an objective measure or evaluation of normal or abnormal biological processes. In the model, the metabolism rate of infected cell has been induced alpha particles traversals, as a biomarker, has been followed to reach oncogenic transformation. The model results have successfully validated in comparison with "in vitro oncogenic transformation data" for C3H 10T1/2 cells. This model has provided an opportunity to study the cellular and molecular changes, at the various stages in radiation carcinogenesis, involving human cells. It has become well known that simulation could be used to investigate complex biomedical systems, in situations where traditional methodologies were difficult or too costly to employ.

  19. Effect of grain boundaries on shock-induced phase transformation in iron bicrystals

    Science.gov (United States)

    Zhang, Xueyang; Wang, Kun; Zhu, Wenjun; Chen, Jun; Cai, Mengqiu; Xiao, Shifang; Deng, Huiqiu; Hu, Wangyu

    2018-01-01

    Non-equilibrium molecular-dynamic simulations with a modified analytic embedded-atom model potential have been performed to investigate the effect of three kinds of grain boundaries (GBs) on the martensitic transformation in iron bicrystals with three different GBs under shock loadings. Our results show that the phase transition was influenced by the GBs. All three GBs provide a nucleation site for the α → ɛ transformation in samples shock-loaded with up = 0.5 km/s, and in particular, the elastic wave can induce the phase transformation at Σ3 ⟨110⟩ twist GB, which indicates that the phase transformation can occur at Σ3 ⟨110⟩ twist GB with a much lower pressure. The effect of GBs on the stress assisted transformation (SAT) mechanisms is discussed. All variants nucleating at the vicinity of these GBs meet the maximum strain work (MSW) criterion. Moreover, all of the variants with the MSW nucleate at Σ5 ⟨001⟩ twist GB and Σ3 ⟨110⟩ tilt GB, but only part of them nucleate at Σ3 ⟨110⟩ twist GB. This is because the coincident planes between both sides of the GB would affect the slip process, which is the second stage of the martensitic transformation and influences the selection of variant. We also find that the martensitic transformation at the front end of the bicrystals would give rise to stress attenuation in samples shock-loaded with up = 0.6 km/s, which makes the GBs seem to be unfavorable to the martensitic transformation. Our findings have the potential to affect the interface engineering and material design under high pressure conditions.

  20. Analysis Strategy for Fracture Assessment of Defects in Ductile Materials

    Energy Technology Data Exchange (ETDEWEB)

    Dillstroem, Peter; Andersson, Magnus; Sattari-Far, Iradj; Weilin Zang (Inspecta Technology AB, Stockholm (Sweden))

    2009-06-15

    The main purpose of this work is to investigate the significance of the residual stresses for defects (cracks) in ductile materials with nuclear applications, when the applied primary (mechanical) loads are high. The treatment of weld-induced stresses as expressed in the SACC/ProSACC handbook and other fracture assessment procedures such as the ASME XI code and the R6-method is believed to be conservative for ductile materials. This is because of the general approach not to account for the improved fracture resistance caused by ductile tearing. Furthermore, there is experimental evidence that the contribution of residual stresses to fracture diminishes as the degree of yielding increases to a high level. However, neglecting weld-induced stresses in general, though, is doubtful for loads that are mostly secondary (e.g. thermal shocks) and for materials which are not ductile enough to be limit load controlled. Both thin-walled and thick-walled pipes containing surface cracks are studied here. This is done by calculating the relative contribution from the weld residual stresses to CTOD and the J-integral. Both circumferential and axial cracks are analysed. Three different crack geometries are studied here by using the finite element method (FEM). (i) 2D axisymmetric modelling of a V-joint weld in a thin-walled pipe. (ii) 2D axisymmetric modelling of a V-joint weld in a thick-walled pipe. (iii) 3D modelling of a X-joint weld in a thick-walled pipe. t. Each crack configuration is analysed for two load cases; (1) Only primary (mechanical) loading is applied to the model, (2) Both secondary stresses and primary loading are applied to the model. Also presented in this report are some published experimental investigations conducted on cracked components of ductile materials subjected to both primary and secondary stresses. Based on the outcome of this study, an analysis strategy for fracture assessment of defects in ductile materials of nuclear components is proposed. A new

  1. Analysis Strategy for Fracture Assessment of Defects in Ductile Materials

    International Nuclear Information System (INIS)

    Dillstroem, Peter; Andersson, Magnus; Sattari-Far, Iradj; Weilin Zang

    2009-06-01

    The main purpose of this work is to investigate the significance of the residual stresses for defects (cracks) in ductile materials with nuclear applications, when the applied primary (mechanical) loads are high. The treatment of weld-induced stresses as expressed in the SACC/ProSACC handbook and other fracture assessment procedures such as the ASME XI code and the R6-method is believed to be conservative for ductile materials. This is because of the general approach not to account for the improved fracture resistance caused by ductile tearing. Furthermore, there is experimental evidence that the contribution of residual stresses to fracture diminishes as the degree of yielding increases to a high level. However, neglecting weld-induced stresses in general, though, is doubtful for loads that are mostly secondary (e.g. thermal shocks) and for materials which are not ductile enough to be limit load controlled. Both thin-walled and thick-walled pipes containing surface cracks are studied here. This is done by calculating the relative contribution from the weld residual stresses to CTOD and the J-integral. Both circumferential and axial cracks are analysed. Three different crack geometries are studied here by using the finite element method (FEM). (i) 2D axisymmetric modelling of a V-joint weld in a thin-walled pipe. (ii) 2D axisymmetric modelling of a V-joint weld in a thick-walled pipe. (iii) 3D modelling of a X-joint weld in a thick-walled pipe. t. Each crack configuration is analysed for two load cases; (1) Only primary (mechanical) loading is applied to the model, (2) Both secondary stresses and primary loading are applied to the model. Also presented in this report are some published experimental investigations conducted on cracked components of ductile materials subjected to both primary and secondary stresses. Based on the outcome of this study, an analysis strategy for fracture assessment of defects in ductile materials of nuclear components is proposed. A new

  2. Effect of Continuous Galvanizing Heat Treatments on the Microstructure and Mechanical Properties of High Al-Low Si Transformation Induced Plasticity Steels

    Science.gov (United States)

    Bellhouse, E. M.; McDermid, J. R.

    2010-02-01

    Heat treatments were performed using an isothermal bainitic transformation (IBT) temperature compatible with continuous hot-dip galvanizing on two high Al-low Si transformation induced plasticity (TRIP)-assisted steels. Both steels had 0.2 wt pct C and 1.5 wt pct Mn; one had 1.5 wt pct Al and the other had 1 wt pct Al and 0.5 wt pct Si. Two different intercritical annealing (IA) temperatures were used, resulting in intercritical microstructures of 50 pct ferrite (α)-50 pct austenite (γ) and 65 pct α-35 pct γ. Using the IBT temperature of 465 °C, five IBT times were tested: 4, 30, 60, 90, and 120 seconds. Increasing the IBT time resulted in a decrease in the ultimate tensile strength (UTS) and an increase in the uniform elongation, yield strength, and yield point elongation. The uniform elongation was higher when using the 50 pct α-50 pct γ IA temperature when compared to the 65 pct α-35 pct γ IA temperature. The best combinations of strength and ductility and their corresponding heat treatments were as follows: a tensile strength of 895 MPa and uniform elongation of 0.26 for the 1.5 pct Al TRIP steel at the 50 pct γ IA temperature and 90-second IBT time; a tensile strength of 880 MPa and uniform elongation of 0.27 for the 1.5 pct Al TRIP steel at the 50 pct γ IA temperature and 120-second IBT time; and a tensile strength of 1009 MPa and uniform elongation of 0.22 for the 1 pct Al-0.5 pct Si TRIP steel at the 50 pct γ IA temperature and 120-second IBT time.

  3. Ion irradiation-induced diffusion in bixbyite-fluorite related oxides: Dislocations and phase transformation

    Energy Technology Data Exchange (ETDEWEB)

    Rolly, Gaboriaud, E-mail: Rolly.gaboriaud@univ-poitiers.fr [Institut Pprime, CNRS-University of Poitiers, SP2MI-BP 30179, 86962 Chasseneuil-Futuroscope (France); Fabien, Paumier [Institut Pprime, CNRS-University of Poitiers, SP2MI-BP 30179, 86962 Chasseneuil-Futuroscope (France); Bertrand, Lacroix [CSIC – University of Sevilla, Avenida Américo Vespucio, 49, 41092 Sevilla (Spain)

    2014-05-01

    Ion-irradiation induced diffusion and the phase transformation of a bixbyite-fluorite related rare earth oxide thin films are studied. This work is focused on yttrium sesquioxide, Y{sub 2}O{sub 3}, thin films deposited on Si (1 0 0) substrates using the ion beam sputtering technique (IBS). As-deposited samples were annealed ant then irradiated at cryogenic temperature (80 K) with 260 keV Xe{sup 2+} at different fluences. The irradiated thin oxide films are characterized by X-ray diffraction. A cubic to monoclinic phase transformation was observed. Analysis of this phenomenon is done in terms of residual stresses. Stress measurements as a function of irradiation fluences were realised using the XRD-sin{sup 2}ψ method. Stress evolution and kinetic of the phase transformation are compared and leads to the role-played by the nucleation of point and extended defects.

  4. Hysteresis and Power-Law Statistics during temperature induced martensitic transformation

    International Nuclear Information System (INIS)

    Paul, Arya; Sengupta, Surajit; Rao, Madan

    2011-01-01

    We study hysteresis in temperature induced martensitic transformation using a 2D model solid exhibiting a square to rhombic structural transition. We find that upon quenching, the high temperature square phase, martensites are nucleated at sites having large non-affineness and ultimately invades the whole of the high temperature square phase. On heating the martensite, the high temperature square phase is restored. The transformation proceeds through avalanches. The amplitude and the time-duration of these avalanches exhibit power-law statistics both during heating and cooling of the system. The exponents corresponding to heating and cooling are different thereby indicating that the nucleation and dissolution of the product phase follows different transformation mechanism.

  5. Hot ductility behavior of boron microalloyed steels

    International Nuclear Information System (INIS)

    Lopez-Chipres, E.; Mejia, I.; Maldonado, C.; Bedolla-Jacuinde, A.; Cabrera, J.M.

    2007-01-01

    The current study analyses the influence of boron contents (between 29 and 105 ppm) on the hot ductility of boron microalloyed steels. For this purpose, hot tensile tests were carried out at different temperatures (700, 800, 900 and 1000 deg. C) at a constant true strain rate of 0.001 s -1 . In general, results revealed an improvement of the hot ductility of steels at increasing boron content. At 700, 900 and 1000 deg. C the ductility is higher than at 800 deg. C, where boron microalloyed steels exhibit a region of ductility loss (trough region). Likewise, dynamic recrystallization only occurred at 900 and 1000 deg. C. The fracture surfaces of the tested steels at temperatures giving the high temperature ductility regime show that the fracture mode is a result of ductile failure, whereas it is ductile-brittle failure in the trough region. Results are discussed in terms of dynamic recrystallization and boron segregation towards austenite grain boundaries, which may retard the formation of pro-eutectoid ferrite and increase grain boundary cohesion

  6. Two-dimensional electrophoretic analysis of transformation-sensitive polypeptides during chemically, spontaneously, and oncogene-induced transformation of rat liver epithelial cells

    DEFF Research Database (Denmark)

    Wirth, P J; Luo, L D; Fujimoto, Y

    1992-01-01

    ; AFB), spontaneously, and oncogene (v-Ha-ras, v-raf, and v-myc/v-raf)-induced transformation of RLE cells. Two-dimensional mapping of [35S]methionine-labeled whole cell lysate, cell-free in vitro translation products and [32P]orthophosphate-labeled polypeptides revealed subsets of polypeptides specific...... for each transformation modality. A search of the RLE protein database indicated the specific subcellular location for the majority of these transformation-sensitive proteins. Significant alterations in the expression of the extracellular matrix protein, fibronectin, as well as tropomyosin......- and intermediate filament-related polypeptides (vimentin, beta-tubulin, the cytokeratins, and actin) were observed among the various transformant cell lines. Immunoprecipitation and Western immunoblot analysis of tropomyosin expression in four individual AFB-, as well as four spontaneously induced, and each...

  7. Canine tracheal epithelial cells are more sensitive than rat tracheal epithelial cells to transforming growth factor beta induced growth inhibition

    International Nuclear Information System (INIS)

    Hubbs, A.F.; Hahn, F.F.; Kelly, G.; Thomassen, D.G.

    1988-01-01

    Transforming growth factor beta (TGFβ) markedly inhibited growth of canine tracheal epithelial (CTE) cells. Reduced responsiveness to TGFβ-induced growth inhibition accompanied neoplastic progression of these cells from primary to transformed to neoplastic. This was similar to the relationship between neoplastic progression and increased resistance to TGFβ-induced growth inhibition seen for rat tracheal epithelial (RTE) cells. The canine cells were more sensitive than rat cells to TGFβ-induced growth inhibition at all stages in the neoplastic process. (author)

  8. Constitutive Model Of Graded Micro-Structure Obtained Via Strain Induced Phase Transformation

    CERN Document Server

    Ortwein, Rafał

    The literature review has been divided into three main sub-chapters. The first one is concentrated on the general information about stainless steels and their applications. It is important to perform a general overview and get an idea where the results of the present thesis could be applied. Description of all the brands of stainless steels, their microstructures and properties are important, as similar characteristics can be found in the newly created functionally graded structures. The second sub-chapter is an overview of the most important constitutive models and the experimental results for materials that undergo plastic strain induced phase transformation. Finally, the last one is devoted to functionally graded microstructures obtained via strain induced martensitic transformation – the subject of particular importance for the present thesis. As a general note, the literature review is organized mainly in a chronological order. In some cases similar publications or publications of the same Authors were...

  9. Conformational transformations induced by the charge-curvature interaction: Mean-field approach

    DEFF Research Database (Denmark)

    Gaididei, Yu B.; Christiansen, Peter Leth; Zakrzewski, W.J.

    2006-01-01

    A simple phenomenological model for describing the conformational dynamics of biological macromolecules via the nonlinearity-induced instabilities is proposed. It is shown that the interaction between charges and bending degrees of freedom of closed molecular aggregates may act as drivers giving ...... impetus to conformational dynamics of biopolymers. It is demonstrated that initially circular aggregates may undergo transformation to polygonal shapes and possible application to aggregates of bacteriochlorophyl a molecules is considered....

  10. Chloride-induced shape transformation of silver nanoparticles in a water environment

    International Nuclear Information System (INIS)

    Zhang, Lan; Li, Xin; He, Rong; Wu, Lijun; Zhang, Liyun; Zeng, Jie

    2015-01-01

    The effects of chloride on dissolution and toxicity of silver nanoparticles (AgNPs) have been well studied. However, their intermediate shapes during the transition have not been illustrated to-date. Herein, the chloride-induced shape transformation process of AgNPs under long-term, low-concentration conditions is explored. A unique triangular Ag–AgCl heterostructure is observed. The structure then evolves into a symmetric hexapod and finally into a smaller AgNP. This transformation process could be affected by other environmental conditions, such as 0.4 mg/mL humic acid, 5% surfactants and 1 mg/mL bovine serum albumin protein. Our results offer new knowledge regarding the shape transformation process of AgNPs in the presence of chloride, which can be valuable in relevant studies concerning the effect of water chemistry on the behavior of AgNPs. - Highlights: • Several significant intermediate structures have been firstly observed during AgNPs shape transformation process. • These findings of intermediate shapes offer the new knowledge on understanding the environmental fate of AgNPs. • The effects of other environmental factors on shape transformation have been well explored. - Significant intermediate structures are discovered during the AgNPs environmental process, enriching the knowledge of understanding the environmental fate of AgNPs

  11. Possible involvement of MSX-2 homeoprotein in v-ras-induced transformation.

    Science.gov (United States)

    Takahashi, C; Akiyama, N; Kitayama, H; Takai, S; Noda, M

    1997-04-01

    A truncated MSX-2 homeoprotein was found to induce flat reversion when expressed in v-Ki-ras-transformed NIH3T3 cells. Although the expression of endogenous MSX-2 gene is low in most of the normal adult tissues examined, it is frequently activated in carcinoma-derived cell lines. Likewise, the gene is inactive in untransformed cells but is transcriptionally activated after transformation by v-Ki-ras oncogene, suggesting that the intact MSX-2 may play a positive, rather than suppressive, role in cell transformation. To test this possibility, we isolated a full-length human MSX-2 cDNA and tested its activities in two cell systems: fibroblast and myoblast. In NIH3T3 fibroblasts, although the gene by itself failed to confer a transformed phenotype, antisense MSX-2 cDNA as well as truncated MSX-2 cDNA interfered with the transforming activities of both v-Ki-ras and v-raf oncogene. In C2C12 myoblasts, MSX-2 was found to suppress MyoD gene expression, as do activated ras oncogenes, under certain culture conditions, and truncated MSX-2 cDNA was found to inhibit the activities of both MSX-2 and ras in this system as well. Our findings not only suggest that the truncated version MSX-2 may act as a dominant suppressor of intact MSX-2 but also raise the possibility that MSX-2 gene may be an important downstream target for the Ras signaling pathways.

  12. Transformation-Induced Relaxation and Stress Recovery of TiNi Shape Memory Alloy

    Directory of Open Access Journals (Sweden)

    Kohei Takeda

    2014-03-01

    Full Text Available The transformation-induced stress relaxation and stress recovery of TiNi shape memory alloy (SMA in stress-controlled subloop loading were investigated based on the local variation in temperature and transformation band on the surface of the tape in the tension test. The results obtained are summarized as follows. (1 In the loading process, temperature increases due to the exothermic martensitic transformation (MT until the holding strain and thereafter temperature decreases while holding the strain constant, resulting in stress relaxation due to the MT; (2 In the unloading process, temperature decreases due to the endothermic reverse transformation until the holding strain and thereafter temperature increases while holding the strain constant, resulting in stress recovery due to the reverse transformation; (3 Stress varies markedly in the initial stage followed by gradual change while holding the strain constant; (4 If the stress rate is high until the holding strain in the loading and unloading processes, both stress relaxation and stress recovery are large; (5 It is important to take into account this behavior in the design of SMA elements, since the force of SMA elements varies even if the atmospheric temperature is kept constant.

  13. Water accelerated transformation of d-limonene induced by ultraviolet irradiation and air exposure.

    Science.gov (United States)

    Li, Li Jun; Hong, Peng; Jiang, Ze Dong; Yang, Yuan Fan; Du, Xi Ping; Sun, Hao; Wu, Li Ming; Ni, Hui; Chen, Feng

    2018-01-15

    d-Limonene is a fragrant chemical that widely exists in aromatic products. Isotopic labelling of water molecules plus GC-MS and GC-PCI-Q-TOF analyses were used to investigate the influence of water molecules on chemical transformation of d-limonene induced by UV irradiation and air exposure. The results showed that the synergistic effect of UV irradiation, air exposure and water presence could facilitate d-limonene transformation into the limonene oxides: p-mentha-2,8-dienols, hydroperoxides, carveols, l-carvone and carvone oxide. UV irradiation, air exposure, or water alone, however, caused negligible d-limonene transformation. With the aid of isotopic labelling of water and oxygen molecules, it was found that water molecules were split into hydrogen radicals and hydroxyl radicals, and the hydrogen radicals, in particular, promoted the transformation reactions. This study has elucidated the mechanism and factors that influence the transformation of d-limonene, which will benefit industries involved in production and storage of d-limonene-containing products. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Unraveling the nature of electric field- and stress- induced structural transformations in soft PZT by a new powder poling technique.

    Science.gov (United States)

    Kalyani, Ajay Kumar; V, Lalitha K; James, Ajit R; Fitch, Andy; Ranjan, Rajeev

    2015-02-25

    A 'powder-poling' technique was developed to study electric field induced structural transformations in ferroelectrics exhibiting a morphotropic phase boundary (MPB). The technique was employed on soft PZT exhibiting a large longitudinal piezoelectric response (d(33) ∼ 650 pC N(-1)). It was found that electric poling brings about a considerable degree of irreversible tetragonal to monoclinic transformation. The same transformation was achieved after subjecting the specimen to mechanical stress, which suggests an equivalence of stress and electric field with regard to the structural mechanism in MPB compositions. The electric field induced structural transformation was also found to be accompanied by a decrease in the spatial coherence of polarization.

  15. Ductility behavior of irradiated path B alloys

    International Nuclear Information System (INIS)

    Yang, W.J.S.; Hamilton, M.L.

    1983-01-01

    The objective of this study was to assess the practicality of using five Path B alloys in their current form as structural materials in the Fusion First-Wall/Blanket by evaluating both their postirradiation ductility and the corresponding microstructures

  16. Hot ductility of continuously cast structural steels

    International Nuclear Information System (INIS)

    Pytel, S.M.

    1995-01-01

    The objective of this investigation was to explain the hot ductility of the structural steels characterized by different amount of carbon and morphology of sulfides. Two different rolling processes were simulated under computer controlled, high temperature deformation MTS system. Results of this study show that morphology of sulfides as well as temperature and amount of deformation are responsible for level of hot ductility of the steel tested. (author)

  17. 46 CFR 56.60-15 - Ductile iron.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Ductile iron. 56.60-15 Section 56.60-15 Shipping COAST... Materials § 56.60-15 Ductile iron. (a) Ductile cast iron components made of material conforming to ASTM A... (incorporated by reference; see 46 CFR 56.01-2). (b) Ductile iron castings conforming to ASTM A 395...

  18. 49 CFR 192.277 - Ductile iron pipe.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Ductile iron pipe. 192.277 Section 192.277 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... Ductile iron pipe. (a) Ductile iron pipe may not be joined by threaded joints. (b) Ductile iron pipe may...

  19. Role of reactive oxygen species in arsenic-induced transformation of human lung bronchial epithelial (BEAS-2B) cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhuo, E-mail: zhuo.zhang@uky.edu [Graduate Center for Toxicology, University of Kentucky, Lexington, KY 40536 (United States); Pratheeshkumar, Poyil; Budhraja, Amit; Son, Young-Ok [Center for Research on Environmental Diseases, University of Kentucky, Lexington, KY 40536 (United States); Kim, Donghern [Graduate Center for Toxicology, University of Kentucky, Lexington, KY 40536 (United States); Shi, Xianglin [Center for Research on Environmental Diseases, University of Kentucky, Lexington, KY 40536 (United States)

    2015-01-09

    Highlights: • Short term exposure of cells to arsenic causes ROS generation. • Chronical exposure of cells to arsenic causes malignant cell transformation. • Inhibition of ROS generation reduces cell transformation by arsenic. • Arsenic-transformed cells exhibit reduced capacity of generating ROS. • Arsenic-transformed cells exhibit increased levels of antioxidants. - Abstract: Arsenic is an environmental carcinogen, its mechanisms of carcinogenesis remain to be investigated. Reactive oxygen species (ROS) are considered to be important. A previous study (Carpenter et al., 2011) has measured ROS level in human lung bronchial epithelial (BEAS-2B) cells and arsenic-transformed BEAS-2B cells and found that ROS levels were higher in transformed cells than that in parent normal cells. Based on these observations, the authors concluded that cell transformation induced by arsenic is mediated by increased cellular levels of ROS. This conclusion is problematic because this study only measured the basal ROS levels in transformed and parent cells and did not investigate the role of ROS in the process of arsenic-induced cell transformation. The levels of ROS in arsenic-transformed cells represent the result and not the cause of cell transformation. Thus question concerning whether ROS are important in arsenic-induced cell transformation remains to be answered. In the present study, we used expressions of catalase (antioxidant against H{sub 2}O{sub 2}) and superoxide dismutase 2 (SOD2, antioxidant against O{sub 2}{sup ·−}) to decrease ROS level and investigated their role in the process of arsenic-induced cell transformation. Our results show that inhibition of ROS by antioxidant enzymes decreased arsenic-induced cell transformation, demonstrating that ROS are important in this process. We have also shown that in arsenic-transformed cells, ROS generation was lower and levels of antioxidants are higher than those in parent cells, in a disagreement with the previous

  20. Role of reactive oxygen species in arsenic-induced transformation of human lung bronchial epithelial (BEAS-2B) cells

    International Nuclear Information System (INIS)

    Zhang, Zhuo; Pratheeshkumar, Poyil; Budhraja, Amit; Son, Young-Ok; Kim, Donghern; Shi, Xianglin

    2015-01-01

    Highlights: • Short term exposure of cells to arsenic causes ROS generation. • Chronical exposure of cells to arsenic causes malignant cell transformation. • Inhibition of ROS generation reduces cell transformation by arsenic. • Arsenic-transformed cells exhibit reduced capacity of generating ROS. • Arsenic-transformed cells exhibit increased levels of antioxidants. - Abstract: Arsenic is an environmental carcinogen, its mechanisms of carcinogenesis remain to be investigated. Reactive oxygen species (ROS) are considered to be important. A previous study (Carpenter et al., 2011) has measured ROS level in human lung bronchial epithelial (BEAS-2B) cells and arsenic-transformed BEAS-2B cells and found that ROS levels were higher in transformed cells than that in parent normal cells. Based on these observations, the authors concluded that cell transformation induced by arsenic is mediated by increased cellular levels of ROS. This conclusion is problematic because this study only measured the basal ROS levels in transformed and parent cells and did not investigate the role of ROS in the process of arsenic-induced cell transformation. The levels of ROS in arsenic-transformed cells represent the result and not the cause of cell transformation. Thus question concerning whether ROS are important in arsenic-induced cell transformation remains to be answered. In the present study, we used expressions of catalase (antioxidant against H 2 O 2 ) and superoxide dismutase 2 (SOD2, antioxidant against O 2 ·− ) to decrease ROS level and investigated their role in the process of arsenic-induced cell transformation. Our results show that inhibition of ROS by antioxidant enzymes decreased arsenic-induced cell transformation, demonstrating that ROS are important in this process. We have also shown that in arsenic-transformed cells, ROS generation was lower and levels of antioxidants are higher than those in parent cells, in a disagreement with the previous report. The

  1. Chronic Exposure to Particulate Nickel Induces Neoplastic Transformation in Human Lung Epithelial Cells

    Directory of Open Access Journals (Sweden)

    Amie L. Holmes

    2013-11-01

    Full Text Available Nickel is a well-known human lung carcinogen with the particulate form being the most potent; however, the carcinogenic mechanism remains largely unknown. Few studies have investigated the genotoxicity and carcinogenicity of nickel in its target cell, human bronchial epithelial cells. Thus, the goal of this study was to investigate the effects of particulate nickel in human lung epithelial cells. We found that nickel subsulfide induced concentration- and time-dependent increases in both cytotoxicity and genotoxicity in human lung epithelial cells (BEP2D. Chronic exposure to nickel subsulfide readily induced cellular transformation, inducing 2.55, 2.9 and 2.35 foci per dish after exposure to 1, 2.5 and 5 μg/cm2 nickel subsulfide, respectively. Sixty-one, 100 and 70 percent of the foci isolated from 1, 2.5, and 5 μg/cm2 nickel subsulfide treatments formed colonies in soft agar and the degree of soft agar colony growth increased in a concentration-dependent manner. Thus, chronic exposure to particulate nickel induces genotoxicity and cellular transformation in human lung epithelial cells.

  2. Dislocation dynamics modelling of the ductile-brittle-transition

    International Nuclear Information System (INIS)

    Hennecke, Thomas; Haehner, Peter

    2009-01-01

    Many materials like silicon, tungsten or ferritic steels show a transition between high temperature ductile fracture with stable crack grow and high deformation energy absorption and low temperature brittle fracture in an unstable and low deformation mode, the ductile-brittle-transition. Especially in steels, the temperature transition is accompanied by a strong increase of the measured fracture toughness over a certain temperature range and strong scatter in the toughness data in this transition regime. The change in fracture modes is affected by dynamic interactions between dislocations and the inhomogeneous stress fields of notches and small cracks. In the present work a dislocation dynamics model for the ductile-brittle-transition is proposed, which takes those interactions into account. The model can explain an increase with temperature of apparent toughness in the quasi-brittle regime and different levels of scatter in the different temperature regimes. Furthermore it can predict changing failure sites in materials with heterogeneous microstructure. Based on the model, the effects of crack tip blunting, stress state, external strain rate and irradiation-induced changes in the plastic flow properties can be discussed.

  3. Potentially exploitable supercritical geothermal resources in the ductile crust

    Science.gov (United States)

    Watanabe, Noriaki; Numakura, Tatsuya; Sakaguchi, Kiyotoshi; Saishu, Hanae; Okamoto, Atsushi; Ingebritsen, Steven E.; Tsuchiya, Noriyoshi

    2017-01-01

    The hypothesis that the brittle–ductile transition (BDT) drastically reduces permeability implies that potentially exploitable geothermal resources (permeability >10−16 m2) consisting of supercritical water could occur only in rocks with unusually high transition temperatures such as basalt. However, tensile fracturing is possible even in ductile rocks, and some permeability–depth relations proposed for the continental crust show no drastic permeability reduction at the BDT. Here we present experimental results suggesting that the BDT is not the first-order control on rock permeability, and that potentially exploitable resources may occur in rocks with much lower BDT temperatures, such as the granitic rocks that comprise the bulk of the continental crust. We find that permeability behaviour for fractured granite samples at 350–500 °C under effective confining stress is characterized by a transition from a weakly stress-dependent and reversible behaviour to a strongly stress-dependent and irreversible behaviour at a specific, temperature-dependent effective confining stress level. This transition is induced by onset of plastic normal deformation of the fracture surface (elastic–plastic transition) and, importantly, causes no ‘jump’ in the permeability. Empirical equations for this permeability behaviour suggest that potentially exploitable resources exceeding 450 °C may form at depths of 2–6 km even in the nominally ductile crust.

  4. Mechanical properties of ground state structures in substitutional ordered alloys: High strength, high ductility and high thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Tawancy, H.M., E-mail: tawancy@kfupm.edu.sa [Center for Engineering Research, Research Institute, King Fahd University of Petroleum and Minerals, KFUPM Box 1639, Dhahran 31261 (Saudi Arabia); Aboelfotoh, M.O., E-mail: oaboelfotoh@gmail.com [Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27606 (United States)

    2014-05-01

    We have studied the effect of atom arrangements in the ground state structures of substitutional ordered alloys on their mechanical properties using nickel–molybdenum-based alloys as model systems. Three alloys with nominal compositions of Ni–19.43 at% Mo, Ni–18.53 at% Mo–15.21 at% Cr and Ni–18.72 at% Mo–6.14 at% Nb are included in the study. In agreement with theoretical predictions, the closely related Pt{sub 2}Mo-type, DO{sub 22} and D1{sub a} superlattices with similar energies are identified by electron diffraction of ground state structures, which can directly be derived from the parent disordered fcc structure by minor atom rearrangements on {420}{sub fcc} planes. The three superlattices are observed to coexist during the disorder–order transformation at 700 °C with the most stable superlattice being determined by the exact chemical composition. Although most of the slip systems in the parent disordered fcc structure are suppressed, many of the twinning systems remain operative in the superlattices favoring deformation by twinning, which leads to considerable strengthening while maintaining high ductility levels. Both the Pt{sub 2}Mo-type and DO{sub 22} superlattices are distinguished by high strength and high ductility due to their nanoscale microstructures, which have high thermal stability. However, the D1{sub a} superlattice is found to exhibit poor thermal stability leading to considerable loss of ductility, which has been correlated with self-induced recrystallization by migration of grain boundaries.

  5. Adaptive Response Against Spontaneous Neoplastic Transformation In Vitro Induced by Ionizing Radiation

    International Nuclear Information System (INIS)

    Redpath, J. Leslie

    2003-01-01

    The goal of this project was to establish a dose response curve for radiation-induced neoplastic transformation of HeLa x skin fibroblast human hybrid cells in vitro under experimental conditions were an adaptive response, if it were induced, would have an opportunity to be expressed. During the first two years of the grant an exhaustive series of experiments were performed and the resulting data were reported at the 2000 Annual Meeting of the Radiation Research Society and then Subsequently published. The data showed that an adaptive response against spontaneous neoplastic transformation was seen up to doses of 10cGy of Cs-137 gamma rays. At dose of 30, 50 and 100 cGy the transformation frequencies were above background. This indicated that for this system, under the specific experimental conditions used, there was a threshold of somewhere between 10 and 30 cGy. The results also indicated some unexpected, though very interesting, correlations with relative risk estimates made from human epidemiologic studies

  6. Intra-hydrogel culture prevents transformation of mesenchymal stem cells induced by monolayer expansion.

    Science.gov (United States)

    Jiang, Tongmeng; Liu, Junting; Ouyang, Yiqiang; Wu, Huayu; Zheng, Li; Zhao, Jinmin; Zhang, Xingdong

    2018-05-01

    In this study, we report that the intra-hydrogel culture system mitigates the transformation of mesenchymal stem cells (MSCs) induced by two-dimensional (2D) expansion. MSCs expanded in monolayer culture prior to encapsulation in collagen hydrogels (group eMSCs-CH) featured impaired stemness in chondrogenesis, comparing with the freshly isolated bone marrow mononuclear cells seeded directly in collagen hydrogels (group fMSCs-CH). The molecular mechanism of the in vitro expansion-triggered damage to MSCs was detected through genome-wide microarray analysis. Results indicated that pathways such as proteoglycans in cancer and pathways in cancer expansion were highly enriched in eMSCs-CH. And multiple up-regulated oncoma-associated genes were verified in eMSCs-CH compared with fMSCs-CH, indicating that expansion in vitro triggered cellular transformation was associated with signaling pathways related to tumorigenicity. Besides, focal adhesion (FA) and mitogen-activated protein kinase (MAPK) signaling pathways were also involved in in vitro expansion, indicating restructuring of the cell architecture. Thus, monolayer expansion in vitro may contribute to vulnerability of MSCs through the regulation of FA and MAPK. This study indicates that intra-hydrogel culture can mitigate the monolayer expansion induced transformation of MSCs and maintain the uniformity of the stem cells, which is a viable in vitro culture system for stem cell therapy.

  7. Position-dependent shear-induced austenite– martensite transformation in double-notched TRIP and dual-phase steel samples

    NARCIS (Netherlands)

    Blondé, R.J.P.; Jimenez-Melero, E.; Anusuya Ponnusami, S.; Zhao, L.; Schell, N.; Brück, E.H.; Van der Zwaag, S.; Van Dijk, N.H.

    2014-01-01

    While earlier studies on transformation-induced-plasticity (TRIP) steels focused on the determination of the austenite-to-martensite decomposition in uniform deformation or thermal fields, the current research focuses on the determination of the local retained austenite-to-martensite transformation

  8. β-carotene and canthaxanthin inhibit chemically- and physically-induced transformation in 10T1/2 cells

    International Nuclear Information System (INIS)

    Pung, A.; Rundhaug, J.E.; Yoshizawa, C.N.; Bertram, J.S.

    1988-01-01

    We have studied the effects of β-carotene (β-C), a vitamin A precursor of plant origin, and canthaxanthin (CTX), a non-provitamin A carotenoid, on the neoplastic transformation of C3H/10T1/2 murine fibroblast cells. We show that both β-C and CTX inhibit 3-methylcholanthrene (MCA)-induced transformation. Both carotenoids failed to inhibit X-ray-induced transformation when the cells were treated prior to and during irradiation. However, when the drugs were added 1 week after X-irradiation and maintained in the medium thereafter, both carotenoids inhibited subsequent development of transformed foci in a dose-dependent manner. Again, CTX was more effective than β-C. The inhibition of MCA-induced transformation was reversible; upon removal of the drug, transformed foci developed within 2 weeks, indicating that the carotenoids were not specifically toxic to initiated cells. Although both carotenoids caused a small dose-dependent decrease in the growth rate of both parental and initiated 10T1/2 cells, they did not markedly affect colony size or number when the cells were treated as in the transformation assays, nor did they influence the expression of neoplasia of two transformed cell lines. We suggest that the carotenoids' lipid anti-oxidant properties may be responsible for their inhibitory actions on transformation. (author)

  9. Combining gradient structure and TRIP effect to produce austenite stainless steel with high strength and ductility

    International Nuclear Information System (INIS)

    Wu, X.L.; Yang, M.X.; Yuan, F.P.; Chen, L.; Zhu, Y.T.

    2016-01-01

    We report a design strategy to combine the benefits from both gradient structure and transformation-induced plasticity (TRIP). The resultant TRIP-gradient steel takes advantage of both mechanisms, allowing strain hardening to last to a larger plastic strain. 304 stainless steel sheets were treated by surface mechanical attrition to synthesize gradient structure with a central coarse-grained layer sandwiched between two grain-size gradient layers. The gradient layer is composed of submicron-sized parallelepiped austenite domains separated by intersecting ε-martensite plates, with increasing domain size along the depth. Significant microhardness heterogeneity exists not only macroscopically between the soft coarse-grained core and the hard gradient layers, but also microscopically between the austenite domain and ε-martensite walls. During tensile testing, the gradient structure causes strain partitioning, which evolves with applied strain, and lasts to large strains. The γ → α′ martensitic transformation is triggered successively with an increase of the applied strain and flow stress. Importantly, the gradient structure prolongs the TRIP effect to large plastic strains. As a result, the gradient structure in the 304 stainless steel provides a new route towards a good combination of high strength and ductility, via the co-operation of both the dynamic strain partitioning and TRIP effect.

  10. Surface mechanical attrition treatment induced phase transformation behavior in NiTi shape memory alloy

    International Nuclear Information System (INIS)

    Hu, T.; Wen, C.S.; Lu, J.; Wu, S.L.; Xin, Y.C.; Zhang, W.J.; Chu, C.L.; Chung, J.C.Y.; Yeung, K.W.K.; Kwok, D.T.K.; Chu, Paul K.

    2009-01-01

    The phase constituents and transformation behavior of the martensite B19' NiTi shape memory alloy after undergoing surface mechanical attrition treatment (SMAT) are investigated. SMAT is found to induce the formation of a parent B2 phase from the martensite B19' in the top surface layer. By removing the surface layer-by-layer, X-ray diffraction reveals that the amount of the B2 phase decreases with depth. Differential scanning calorimetry (DSC) further indicates that the deformed martensite in the sub-surface layer up to 300 μm deep exhibits the martensite stabilization effect. The graded phase structure and transformation behavior in the SMATed NiTi specimen can be attributed to the gradient change in strain with depth.

  11. Micro-thermomechanical constitutive model of transformation induced plasticity and its application on armour steel

    Energy Technology Data Exchange (ETDEWEB)

    Sun, C.Y. [School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083 (China)], E-mail: suncy@me.ustb.edu.cn; Fang, G.; Lei, L.P.; Zeng, P. [Key Laboratory of Advanced Materials Processing Technology, Ministry of Education, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China)

    2009-01-15

    Based on the crystallographic theory of martensitic transformation and internal variable constitutive theory, a micromechanical constitutive model of martensitic transformation induced plasticity was developed. Plastic strains of product and parent phases as well as the volume fraction of each martensitic variant were considered as internal variables describing the microstructure evolution. The plasticity flow both in austenite and martensitic variants domain is described by J{sub 2} flow theory. The thermodynamic driving force acting on these internal variables was obtained through the determination of the intrinsic dissipation due to plastic flow and the growth of martensitic domains. The evolution laws of the internal variables are derived, furthermore macroscopic response due to the change of internal variables is obtained. Thermomechanical behavior of armour steel under uniaxial loading was tested which showed a good agreement with experimental results.

  12. Micro-thermomechanical constitutive model of transformation induced plasticity and its application on armour steel

    International Nuclear Information System (INIS)

    Sun, C.Y.; Fang, G.; Lei, L.P.; Zeng, P.

    2009-01-01

    Based on the crystallographic theory of martensitic transformation and internal variable constitutive theory, a micromechanical constitutive model of martensitic transformation induced plasticity was developed. Plastic strains of product and parent phases as well as the volume fraction of each martensitic variant were considered as internal variables describing the microstructure evolution. The plasticity flow both in austenite and martensitic variants domain is described by J 2 flow theory. The thermodynamic driving force acting on these internal variables was obtained through the determination of the intrinsic dissipation due to plastic flow and the growth of martensitic domains. The evolution laws of the internal variables are derived, furthermore macroscopic response due to the change of internal variables is obtained. Thermomechanical behavior of armour steel under uniaxial loading was tested which showed a good agreement with experimental results

  13. A Small Molecule Inhibitor Selectively Induces Apoptosis in Cells Transformed by High Risk Human Papilloma Viruses.

    Directory of Open Access Journals (Sweden)

    Amy K Sheaffer

    Full Text Available A phenotypic high-throughput cell culture screen was performed to identify compounds that prevented proliferation of the human Papilloma virus type 16 (HPV-16 transformed cell line Ca Ski. A series of quinoxaline compounds exemplified by Compound 1 was identified. Testing against a panel of cell lines demonstrated that Compound 1 selectively inhibited replication of all HPV-16, HPV-18, and HPV-31 transformed cell lines tested with 50% Inhibitory Concentration (IC50 values of 2 to 8 μM relative to IC50 values of 28 to 73 μM in HPV-negative cell lines. Treatment with Compound 1 resulted in a cascade of multiple apoptotic events, including selective activation of effector caspases 3 and 7, fragmentation of cellular DNA, and PARP (poly(ADP-ribose polymerase cleavage in HPV-positive cells relative to HPV-negative cells. Unregulated proliferation of HPV transformed cells is dependent on the viral oncogenes, E6 and E7. Treatment with Compound 1 resulted in a decrease in HPV E7 protein in Ca Ski cells. However, the timing of this reduction relative to other effects of compound treatment suggests that this was a consequence, rather than a cause, of the apoptotic cascade. Likewise, compound treatment resulted in no obvious effects on the E6- and E7- mediated down regulation of p53 and Rb, or their downstream effectors, p21 or PCNA. Further investigation of apoptotic signals induced by Compound 1 revealed cleavage of Caspase-8 in HPV-positive cells as early as 2 hours post-treatment, suggesting the compound initiates apoptosis through the extrinsic, death receptor-mediated, pathway of cell death. These studies provide proof of concept that cells transformed by oncogenic Papillomaviruses can be selectively induced to undergo apoptosis by compound treatment.

  14. TPA-inducible proteins may account for sensitivity to promotion of transformation

    International Nuclear Information System (INIS)

    Hirano, K.; Smith, B.; Colburn, N.H.

    1986-01-01

    The preneoplastic JB6 mouse epidermal cell system includes cell lines sensitive (P + ) or resistant (P - ) to tumor promoter induced neoplastic transformation. The authors investigated whether a difference in TPA-inducible proteins may explain this differential sensitivity. The synthesis of a 39 Kd cytoplasmic protein (Major Excreted Protein) was TPA-inducible, but to a similar extent in both P + and P - cells. TPA stimulated phosphorylation but not synthesis of the previously described stress protein pp80 in both P + and P - cells from 1 to 5 hr after treatment. Pulse labelling of P + and P - cells with 35 S-methionine revealed a TPA dependent P + specific transient increase in the synthesis of 58Kd protein. Induction was observed at 1 hr, and returned to basal levels by 4 hr and 20 hr, in nuclear and cytoplasmic fractions, respectively. This protein is not phosphorylated in response to TPA treatment. P + cells differ from P - cells in one or more genes that specify sensitivity to promotion of transformation, designated pro genes. Antibodies to three peptides representing the pro-1 open reading frame were used in immunoprecipitation and Western blotting to isolate the pro-1 gene product. A 43 Kd protein was immunologically responsive to the pro-1 peptide antibodies, and showed an increased signal 40 min after TPA treatment. Since the predicted molecular weight of a pro-1 gene product is only 7 Kd, the possibility of a modification of the protein by poly(ADP-ribosylation) or glycosylation is being investigated

  15. Irradiation and inhomogeneity effects on ductility and toughness of (ODS)-7 -13Cr steels

    International Nuclear Information System (INIS)

    Preininger, D.

    2007-01-01

    Full text of publication follows: The superimposed effect of irradiation defect and structural inhomogeneity formation on tensile ductility and dynamic toughness of ferritic-martensitic 7-13CrW(Mo)VTa(Nb) and oxide dispersion-strengthened (ODS)-7-13CrWVTa(Ti)- RAFM steels has been examined by work hardening and local stress/strain-induced ductile fracture models. Structural inhomogeneities which strongly promoting plastic instability and localized flow might be formed by the applied fabrication process, high dose irradiation and additionally further during deformation by enhanced local dislocation generation around fine particles or due to slip band formation with localized heating at high impact strain rates ε'. The work hardening model takes into account superimposed dislocation multiplication from stored dislocations, dispersions and also grain boundaries as well as annihilation by cross-slip. Analytical relations have been deduced from the model describing uniform ductility and ductile upper shelf energy (USE) observed from Charpy-impact testes. Especially, the influence of different irradiation defects like atomic clusters, dislocation loops and coherent chromium-rich α'- precipitates have been considered together with effects from strain rate as well as irradiation (TI) and test temperature TT. Strengthening by clusters and more pronounced by dislocation loops formed at higher TI>250 deg. C reduces uniform ductility and also distinctly stronger dynamic toughness USE. A superimposed hardening by the α'- formation in higher Cr containing 9-13Cr steels strongly reduces toughness assisted by a combined grain-boundary embrittlement with reduction of the ductile fracture stress. But that improves work hardening and uniform ductility as observed particularly due to nano-scale Y 2 O 3 - dispersions in ODS-RAFM steels. For ODS- steels additionally the strength-induced reduction of toughness is diminished by a combined microstructural-induced increase of the ductile

  16. Selenium and vitamin E inhibit radiogenic and chemically induced transformation in vitro via different mechanisms

    International Nuclear Information System (INIS)

    Borek, C.; Ong, A.; Mason, H.; Donahue, L.; Biaglow, J.E.

    1986-01-01

    Results from in vivo and in vitro studies showing that antioxidants may act as anticarcinogens support the role of active oxygen in carcinogenesis and provide impetus for exploring the functions of dietary antioxidants in cancer prevention by using in vitro models. The authors examined the single and combined effects of selenium, a component of glutathione peroxidase, and vitamin E, a known antioxidant, on cell transformation induced in C3H/10T-1/2 cells by x-rays, benzo[a]pyrene, or tryptophan pyrolysate and on the levels of cellular scavenging systems peroxide destruction. Incubation of C3H/10T-1/2 cells with 2.5 μM Na 2 SeO 3 (selenium) or with 7 μM α-tocopherol succinate (vitamin E) 24 hr prior to exposure to x-rays or the chemical carcinogens resulted in an inhibition of transformation by each of the antioxidants with an additive-inhibitory action when the two nutrients were combined. Cellular pretreatment with selenium resulted in increased levels of cellular glutathione peroxidase, catalase, and nonprotein thiols (glutathione) and in an enhanced destruction of peroxide. The results support our earlier studies showing that free radical-mediated events play a role in radiation and chemically induced transformation. They indicate that selenium and vitamin E act alone and in additive fashion as radioprotecting and chemopreventing agents. The results further suggest that selenium confers protection in part by inducing or activating cellular free-radical scavenging systems and by enhancing peroxide breakdown while vitamin E appears to confer its protection by and alternate complementary mechanism

  17. 4-Hydroxyestradiol induces mammary epithelial cell transformation through Nrf2-mediated heme oxygenase-1 overexpression

    OpenAIRE

    Park, Sin-Aye; Lee, Mee-Hyun; Na, Hye-Kyung; Surh, Young-Joon

    2016-01-01

    Estrogen (17?-estradiol, E2) undergoes oxidative metabolism by CYP1B1 to form 4-hydroxyestradiol (4-OHE2), a putative carcinogenic metabolite of estrogen. Our previous study showed that 4-OHE2-induced production of reactive oxygen species contributed to neoplastic transformation of human breast epithelial (MCF-10A) cells. In this study, 4-OHE2, but not E2, increased the expression of heme oxygenase-1 (HO-1), a sensor and regulator of oxidative stress, in MCF-10A cells. Silencing the HO-1 gene...

  18. Transformations of diaziridines and their fused analogues induced by electrophilic reagents

    International Nuclear Information System (INIS)

    Makhova, Nina N; Shevtsov, Alexander V; Petukhova, Vera Yu

    2011-01-01

    The review deals with transformations of mono- and bicyclic diaziridine derivatives with different types of substitution induced by electrophilic reagents (protic acids, Lewis acids, alkylating and acylating agents, carbonyl compounds, heterocumulenes, activated alkenes and alkynes and transition metal salts). The characteristic features of the reactions are considered as functions of the structures of the starting diaziridines and the nature of the reaction medium (organic solvents, ionic liquids). Prospects of the use of diaziridine derivatives as readily available precursors for the synthesis of various nitrogen-containing heterocyclic systems based on the diaziridine ring expansion reactions are considered. The bibliography includes 136 references.

  19. Microstructure and phase transformation on milled and unmilled Ti induced by water quenching

    CSIR Research Space (South Africa)

    Bolokang, AS

    2014-10-01

    Full Text Available Materials Letters Vol. 132 Microstructure and phase transformation on milled and unmilled Ti induced by water quenching A.S.Bolokang a,b,n, M.J.Phasha c, D.E.Motaung b, F.R.Cummings a,d, T.F.G.Muller a, C.J.Arendse a a Department of...Physics,UniversityoftheWesternCape,PrivateBagx17,Bellville7535,SouthAfrica bDST/CSIR Nanotechnology InnovationCentre ,National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, P.O.Box395, Pretoria 0001, SouthAfrica c Transnet Engineering, Product...

  20. Baicalein has protective effects on the 17β-estradiol-induced transformation of breast epithelial cells.

    Science.gov (United States)

    Chen, Yan; Wang, Jing; Hong, Duan-Yang; Chen, Lin; Zhang, Yan-Yan; Xu, Yi-Ni; Pan, Di; Fu, Ling-Yun; Tao, Ling; Luo, Hong; Shen, Xiang-Chun

    2017-02-07

    Epidemiologic and systematic studies have indicated that flavonoid consumption is associated with a lower incidence of breast cancer. Baicalein is the primary flavonoid derived from the roots of Scutellaria baicalensis Georgi. In the current study, the long-term exposure of breast epithelial cells to 17β-estradiol (E2) was used to investigate the chemopreventive potential of baicalein on neoplastic transformation. The results demonstrated that baicalein significantly inhibited E2-induced cell growth, motility, and invasiveness, and suppressed E2-induced misshapen acini formation in 3D cultures. Furthermore, it inhibited the ability of E2-induced cells to form clones in agarose and tumors in NOD/SCID immunodeficient mice. Docking studies using Sybyl-X 1.2 software showed that baicalein could bind to both estrogen receptor-α (ERa) and G-protein coupled estrogen receptor 30 (GPR30), which are two critical E2-mediated pathways. Baicalein prevented the E2-induced ERa-mediated activation of nuclear transcriptional signaling by interfering with the trafficking of ERa into the nucleus and subsequent binding to estrogen response elements, thereby decreasing the mRNA levels of ERa target genes. It also inhibited E2-induced GPR30-mediated signal transduction, as well as the transcription of GPR30-regulated genes. Therefore, these results suggest that baicalein is a potential drug for reducing the risk of estrogen-dependent breast cancer.

  1. Shape transformation of silver nanospheres to silver nanoplates induced by redox reaction of hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Parnklang, Tewarak; Lamlua, Banjongsak; Gatemala, Harnchana; Thammacharoen, Chuchaat [Department of Chemistry, Faculty of Science, Chulalongkorn University, 254 Phyathai Road, Patumwan, Bangkok 10330 (Thailand); Kuimalee, Surasak [Industrial Chemistry and Textile Technology Programme, Faculty of Science, Maejo University, Chiang Mai 50290 (Thailand); Lohwongwatana, Boonrat [Metallurgical Engineering Department, Faculty of Engineering, Chulalongkorn University, 254 Phyathai Road, Patumwan, Bangkok 10330 (Thailand); Ekgasit, Sanong, E-mail: sanong.e@chula.ac.th [Department of Chemistry, Faculty of Science, Chulalongkorn University, 254 Phyathai Road, Patumwan, Bangkok 10330 (Thailand)

    2015-03-01

    In this paper we demonstrate a simple and rapid shape transformation of silver nanospheres (AgNSs) to silver nanoplates (AgNPls) using the oxidation and reduction capabilities of hydrogen peroxide. AgNPls having tunable surface plasmon resonance across the visible region with average size of 40–100 nm and thickness of 10–15 nm can be fabricated within 2 min simply by adding H{sub 2}O{sub 2} into a colloid of AgNSs with average particle size of 7 nm. The efficiency of H{sub 2}O{sub 2} as a shape-transforming agent depends strongly on its concentration, pH of the AgNS colloid, and the employed stabilizers. H{sub 2}O{sub 2} oxidizes AgNSs to silver ions while concertedly reduces silver ions to silver atom necessary for the growth of AgNPls. The shape transformation reaction was conducted at a relatively low concentration of H{sub 2}O{sub 2} in order to minimize the oxidative dissolution while facilitating kinetically controlled growth of AgNPls under a near neutral pH. Polyvinyl-pyrrolidone is an effective steric stabilizer preventing aggregation while assisting the growth of AgNPls. Trisodium citrate inhibits the formation of AgNPls under the H{sub 2}O{sub 2} reduction as it forms a stable complex with silver ions capable of withstanding the weakly reducing power of H{sub 2}O{sub 2}. After a complete consumption of AgNSs, large nanoplates grows with an expense of smaller nanoplates. The growth continues until H{sub 2}O{sub 2} is exhausted. A high concentration H{sub 2}O{sub 2} promotes catalytic decomposition of H{sub 2}O{sub 2} on the surface of AgNSs and oxidative dissolution of AgNSs without a formation of AgNPls. - Graphical abstract: Proposed mechanism for the shape transformation of AgNSs to AgNPls induced by the oxidation/reduction of H{sub 2}O{sub 2}. - Highlights: • Rapid shape transformation of silver nanospheres to nanoplates by H{sub 2}O{sub 2}. • Structural change completes in 2 min with a yellow-to-blue color change. • Selective fabrication of

  2. Ductilization of Cr via oxide dispersions

    International Nuclear Information System (INIS)

    Brady, M.P.; Wright, I.G.; Anderson, I.M.; Sikka, V.K.; Ohriner, E.K.; Walls, C.; Westmoreland, G.; Weaver, M.L.

    2001-01-01

    Work by Scruggs et al. in the 1960's demonstrated that up to 20 % tensile ductility could be achieved at room-temperature in sintered and extruded powder metallurgical Cr alloyed with MgO. During sintering, much of the MgO converts to a MgCr 2 O 4 spinel, which was hypothesized to getter nitrogen from the Cr, rendering it ductile. Recent efforts at Oak Ridge National Laboratory (ORNL) have succeeded in duplicating this original effect. Preliminary results suggest that the ductilization mechanism may be more complicated than the simple nitrogen gettering mechanism proposed by Scruggs, as some ductility was observed at room-temperature in Cr-MgO alloys containing nitride precipitates. Results of microstructural characterization and room-temperature mechanical property studies are presented for Cr-6MgO-(0-2.2) Ti wt.% as a function of hot-pressing and extrusion. Possible mechanisms by which the MgO additions may improve the room-temperature ductility of Cr are discussed. (author)

  3. Elevated temperature ductility of types 304 and 316 stainless steel

    International Nuclear Information System (INIS)

    Sikka, V.K.

    1978-01-01

    Austenitic stainless steel types 304 and 316 are known for their high ductility and toughness. However, the present study shows that certain combinations of strain rate and test temperature can result in a significant loss in elevated-temperature ductility. Such a phenomenon is referred to as ductility minimum. The strain rate, below which ductility loss is initiated, decreases with decrease in test temperature. Besides strain rate and temperature, the ductility minimum was also affected by nitrogen content and thermal aging conditions. Thermal aging at 649 0 C was observed to eliminate the ductility minimum at 649 0 C in both types 304 and 316 stainless steel. Such an aging treatment resulted in a higher ductility than the unaged value. Aging at 593 0 C still resulted in some loss in ductility. Current results suggest that ductility-minimum conditions for stainless steel should be considered in design, thermal aging data analysis, and while studying the effects of chemical composition

  4. Experimental and theoretical investigation of column - flat slab joint ductility

    International Nuclear Information System (INIS)

    Iskhakov, I.; Ribakov, Y.; Shah, A.

    2009-01-01

    Most modern seismic codes use ductility as one of the basic design parameters. Actually, ductility defines the ability of a structure or its elements to absorb energy by plastic deformations. Until the end of the previous century ductility was defined qualitatively. Most research works related to ductility are focused on structural elements' sections. This study was aimed at complex experimental and theoretical investigation of flat slab-column joints ductility. It is one of the first attempts to obtain quantitative values of joint's ductility for the case of high strength concrete columns and normal strength concrete slabs. It was shown that the flat slab-column joint is a three-dimension (3D) element and its ductility in horizontal and vertical directions are different. This is the main difference between ductility of elements and joint ductility. In case of flat slab-column joints, essential contribution to joint's ductility can be obtained due to the slab's confining effect. Based on experimental data, the authors demonstrate that flat slab-column joint's ductility depends on the joint's confining effect in two horizontal and vertical directions. Furthermore, the influence of slab load intensity and slab reinforcement ratio on the joint's ductility is performed in this study. It is also demonstrated that the effect of the ratio between the slab thickness and the column's section dimension on the ductility parameter is significant. Equations for obtaining a quantitative value of a flat slab-column joint's ductility parameter were developed.

  5. Electric-field-induced paraelectric to ferroelectric phase transformation in prototypical polycrystalline BaTiO3

    International Nuclear Information System (INIS)

    Wang, Zhiyang; Hinterstein, Manuel; Daniels, John E.; Webber, Kyle G.; Hudspeth, Jessica M.

    2014-01-01

    An electric-field-induced paraelectric cubic to ferroelectric tetragonal phase transformation has been directly observed in prototypical polycrystalline BaTiO 3 at temperatures above the Curie point (T C ) using in situ high-energy synchrotron X-ray diffraction. The transformation persisted to a maximum temperature of 4 °C above T C . The nature of the observed field-induced transformation and the resulting development of domain texture within the induced phase were dependent on the proximity to the transition temperature, corresponding well to previous macroscopic measurements. The transition electric field increased with increasing temperature above T C , while the magnitude of the resultant tetragonal domain texture at the maximum electric field (4 kV mm −1 ) decreased at higher temperatures. These results provide insights into the phase transformation behavior of a prototypical ferroelectric and have important implications for the development of future large-strain phase-change actuator materials.

  6. Kinetic analysis of temperature-induced transformation of zeolite 4A to low-carnegieite

    International Nuclear Information System (INIS)

    Kosanovic, C.; Subotic, B.; Ristic, A.

    2004-01-01

    Kinetics of the isothermal amorphization of zeolite 4A and recrystallization of the formed amorphous phase to low-carnegieite at three different temperatures were investigated by powder X-ray diffraction method. Changes in the fractions f A of zeolite 4A, f a of amorphous aluminosilicate and f C of low-carnegieite during heating of zeolite 4A, show that amorphization and recrystallization take place simultaneously. Kinetic analyzes of single processes (amorphization, recrystallization) as well as solution of the population balance of the entire transformation process (simultaneous transformation of zeolite 4A into amorphous aluminosilicate and its recrystallization into low-carnegieite) have shown that: (A) the transformation of zeolite 4A takes place by a random, diffusion-limited agglomeration of the short-range-ordered aluminosilicate subunits formed by thermally induced breaking of Si-O-Si and Si-O-Al bonds between different building units of zeolite framework; and (B) the crystallization of low-carnegieite occurs by homogeneous nucleation of low-carnegieite inside the matrix of amorphous aluminosilicate and diffusion-controlled, one-dimensional growth of the nuclei, thus forming needle-shaped crystals of low-carnegieite

  7. Analysis of the strain induced martensitic transformation in austenitic steel subjected to dynamic perforation

    Directory of Open Access Journals (Sweden)

    Zaera R.

    2012-08-01

    Full Text Available An experimental and numerical analysis on the martensitic transformation in AISI 304 steel sheets subjected to perforation by conical and hemispherical projectiles is reported. Two target thicknesses are considered, 0.5 and 1.0 mm, and impact velocities range from 35 to 200 m/s. The perforation mechanisms are identified and the effect of the projectile nose-shape on the ability of the target for energy absorption is evaluated. Martensite has been detected in all the impacted samples and the role played by the projectile nose-shape on the transformation is highlighted. A 3D model implemented in ABAQUS/Explicit allowed to simulate the perforation tests. The material is defined through a constitutive description developed by the authors to describe the strain induced martensitic transformation taking place in metastable austenitic steels at high strain rates. The numerical results are compared with the experimental evidence and satisfactory matching is obtained. The numerical model succeeds in describing the perforation mechanisms associated to each projectile-target configuration analysed.

  8. Understanding Strain-Induced Phase Transformations in BiFeO3 Thin Films.

    Science.gov (United States)

    Dixit, Hemant; Beekman, Christianne; Schlepütz, Christian M; Siemons, Wolter; Yang, Yongsoo; Senabulya, Nancy; Clarke, Roy; Chi, Miaofang; Christen, Hans M; Cooper, Valentino R

    2015-08-01

    Experiments demonstrate that under large epitaxial strain a coexisting striped phase emerges in BiFeO 3 thin films, which comprises a tetragonal-like ( T ') and an intermediate S ' polymorph. It exhibits a relatively large piezoelectric response when switching between the coexisting phase and a uniform T ' phase. This strain-induced phase transformation is investigated through a synergistic combination of first-principles theory and experiments. The results show that the S ' phase is energetically very close to the T ' phase, but is structurally similar to the bulk rhombohedral ( R ) phase. By fully characterizing the intermediate S ' polymorph, it is demonstrated that the flat energy landscape resulting in the absence of an energy barrier between the T ' and S ' phases fosters the above-mentioned reversible phase transformation. This ability to readily transform between the S ' and T ' polymorphs, which have very different octahedral rotation patterns and c / a ratios, is crucial to the enhanced piezoelectricity in strained BiFeO 3 films. Additionally, a blueshift in the band gap when moving from R to S ' to T ' is observed. These results emphasize the importance of strain engineering for tuning electromechanical responses or, creating unique energy harvesting photonic structures, in oxide thin film architectures.

  9. Drinking water disinfection byproduct iodoacetic acid induces tumorigenic transformation of NIH3T3 cells.

    Science.gov (United States)

    Wei, Xiao; Wang, Shu; Zheng, Weiwei; Wang, Xia; Liu, Xiaolin; Jiang, Songhui; Pi, Jingbo; Zheng, Yuxin; He, Gengsheng; Qu, Weidong

    2013-06-04

    Iodoacetic acid (IAA) and iodoform (IF) are unregulated iodinated disinfection byproducts (DBPs) found in drinking water. Their presence in the drinking water of China has not been documented. Recently, the carcinogenic potential of IAA and IF has been a concern because of their mutagenicity in bacteria and genotoxicity in mammalian cells. Therefore, we measured their concentrations in Shanghai drinking water and assessed their cytotoxicity, genotoxicity, and ability to transform NIH3T3 cells to tumorigenic lines. The concentrations of IAA and IF in Shanghai drinking water varied between summer and winter with maximum winter levels of 2.18 μg/L IAA and 0.86 μg/L IF. IAA with a lethal concentration 50 (LC50) of 2.77 μM exhibited more potent cytotoxicity in NIH3T3 cells than IF (LC50 = 83.37 μM). IAA, but not IF, induced a concentration-dependent DNA damage measured by γ-H2AX staining and increased tail moment in single-cell gel electrophoresis. Neither IAA nor IF increased micronucleus frequency. Prolonged exposure of NIH3T3 cells to IAA increased the frequencies of transformed cells with anchorage-independent growth and agglutination with concanavalin A. IAA-transformed cells formed aggressive fibrosarcomas after inoculation into Balb/c nude mice. This study demonstrated that IAA has a biological activity that is consistent with a carcinogen and human exposure should be of concern.

  10. Ozone acts alone and synergistically with ionizing radiation to induce in vitro neoplastic transformation

    Energy Technology Data Exchange (ETDEWEB)

    Borek, C; Zaider, M; Ong, A; Mason, H; Witz, G

    1986-09-01

    Ozone, a major chemical oxidant in the atmosphere, is an environmental air pollutant whose ability to act as a direct carcinogen is unclear. Using in vitro transformation, a technique which permits the study of oncogenesis in the absence of host specific effects, it is reported for the first time that ozone (5 p.p.m. for 5 min) induces neoplastic transformation in vitro in both primary hamster embryo cells and mouse fibroblast cultures (C3H/10-1/2). Exposure of the hamster and mouse cells to ozone also results in enhanced levels of free radical-mediated lipid peroxidation products. The carcinogenic interaction between ozone and ionizing radiation is also reported. Exposure of the cells to 3 or 4 Gy of ..gamma..-rays, 2 h prior to O/sub 3/ treatment, results in markedly enhanced rates of transformation, statistically consistent with a synergistic interaction between the agents. The results demonstrate that O/sub 3/ acts as a direct carcinogen and co-carcinogen on susceptible cells, therefore having important consequences for public health.

  11. Phase transformation induced by swift heavy ion irradiation of pure metals

    International Nuclear Information System (INIS)

    Dammak, H.; Dunlop, A.; Lesueur, D.

    1996-01-01

    It is now unambiguously established that high electronic energy deposition (HEED), obtained by swift heavy ion irradiation, plays an important role in the damage processes of pure metallic targets: (i) annealing of the defects created by elastic collisions in Fe, Nb, Ni and Pt, and (ii) creation of additional defects in Co, Fe, Ti and Zr. For Ti, we have recently evidenced by transmission electron microscopy observations that the damage creation by HEED is very important and leads to a phase transformation. Titanium evolves from the equilibrium hcp alpha-phase to the high pressure omega-phase. We studied the influence of three parameters on this phase transformation: ion fluence, electronic stopping power and irradiation temperature. The study of Ti and the results concerning other metals (Fe, Zr, etc.) and the semi-metal Bi allow us to propose criteria to predict in which metals HEED could induce damage: those which undergo a phase transformation under high pressure. As a matter of fact, beryllium is strongly damaged when submitted to HEED and seems to behave very similarly to titanium. The fact that such phase changes from a crystalline form to another form were only observed in those metals in which high pressure phases exist in the pressure-temperature diagram, strongly supports the Coulomb explosion model in which the generation of (i) a shock wave and (ii) collective atomic movements are invoked to account for the observed damage creation. (orig.)

  12. Ductile-brittle transition of thoriated chromium.

    Science.gov (United States)

    Wilcox, B. A.; Veigel, N. D.; Clauer, A. H.

    1972-01-01

    Unalloyed chromium and chromium containing approximately 3 wt % ThO2 were prepared from powder produced by a chemical vapor deposition process. When rolled to sheet and tested in tension, it was found that the thoriated material had a lower ductile-to-brittle transition temperature (DBTT) than unalloyed chromium. This ductilizing was evident both in the as-rolled condition and after the materials had been annealed for 1 hour at 1200 C. The improved ductility in thoriated chromium may be associated with several possible mechanisms: (1) particles may disperse slip, such that critical stress or strain concentrations for crack nucleation are more difficult to achieve; (2) particles may act as dislocation sources, thus providing mobile dislocations in this normally source-poor material, in a manner similar to prestraining; and (3) particles in grain boundaries may help to transmit slip across the boundaries, thus relieving stress concentrations and inhibiting crack nucleation.

  13. Analyses of cavitation instabilities in ductile metals

    DEFF Research Database (Denmark)

    Tvergaard, Viggo

    2007-01-01

    Cavitation instabilities have been predicted for a single void in a ductile metal stressed under high triaxiality conditions. In experiments for a ceramic reinforced by metal particles a single dominant void has been observed on the fracture surface of some of the metal particles bridging a crack......, and also tests for a thin ductile metal layer bonding two ceramic blocks have indicated rapid void growth. Analyses for these material configurations are discussed here. When the void radius is very small, a nonlocal plasticity model is needed to account for observed size-effects, and recent analyses......, while the surrounding voids are represented by a porous ductile material model in terms of a field quantity that specifies the variation of the void volume fraction in the surrounding metal....

  14. Integrative pathway dissection of molecular mechanisms of moxLDL-induced vascular smooth muscle phenotype transformation

    Directory of Open Access Journals (Sweden)

    Karagiannis George S

    2013-01-01

    Full Text Available Abstract Background Atherosclerosis (AT is a chronic inflammatory disease characterized by the accumulation of inflammatory cells, lipoproteins and fibrous tissue in the walls of arteries. AT is the primary cause of heart attacks and stroke and is the leading cause of death in Western countries. To date, the pathogenesis of AT is not well-defined. Studies have shown that the dedifferentiation of contractile and quiescent vascular smooth muscle cells (SMC to the proliferative, migratory and synthetic phenotype in the intima is pivotal for the onset and progression of AT. To further delineate the mechanisms underlying the pathogenesis of AT, we analyzed the early molecular pathways and networks involved in the SMC phenotype transformation. Methods Quiescent human coronary artery SMCs were treated with minimally-oxidized LDL (moxLDL, for 3 hours and 21 hours, respectively. Transcriptomic data was generated for both time-points using microarrays and was subjected to pathway analysis using Gene Set Enrichment Analysis, GeneMANIA and Ingenuity software tools. Gene expression heat maps and pathways enriched in differentially expressed genes were compared to identify functional biological themes to elucidate early and late molecular mechanisms of moxLDL-induced SMC dedifferentiation. Results Differentially expressed genes were found to be enriched in cholesterol biosynthesis, inflammatory cytokines, chemokines, growth factors, cell cycle control and myogenic contraction themes. These pathways are consistent with inflammatory responses, cell proliferation, migration and ECM production, which are characteristic of SMC dedifferentiation. Furthermore, up-regulation of cholesterol synthesis and dysregulation of cholesterol metabolism was observed in moxLDL-induced SMC. These observations are consistent with the accumulation of cholesterol and oxidized cholesterol esters, which induce proinflammatory reactions during atherogenesis. Our data implicate for the

  15. Spectral induced polarization and electrodic potential monitoring of microbially mediated iron sulfide transformations

    Energy Technology Data Exchange (ETDEWEB)

    Hubbard, Susan; Personna, Y.R.; Ntarlagiannis, D.; Slater, L.; Yee, N.; O' Brien, M.; Hubbard, S.

    2008-02-15

    Stimulated sulfate-reduction is a bioremediation technique utilized for the sequestration of heavy metals in the subsurface.We performed laboratory column experiments to investigate the geoelectrical response of iron sulfide transformations by Desulfo vibriovulgaris. Two geoelectrical methods, (1) spectral induced polarization (SIP), and (2) electrodic potential measurements, were investigated. Aqueous geochemistry (sulfate, lactate, sulfide, and acetate), observations of precipitates (identified from electron microscopy as iron sulfide), and electrodic potentials on bisulfide ion (HS) sensitive silver-silver chloride (Ag-AgCl) electrodes (630 mV) were diagnostic of induced transitions between an aerobic iron sulfide forming conditions and aerobic conditions promoting iron sulfide dissolution. The SIP data showed 10m rad anomalies during iron sulfide mineralization accompanying microbial activity under an anaerobic transition. These anomalies disappeared during iron sulfide dissolution under the subsequent aerobic transition. SIP model parameters based on a Cole-Cole relaxation model of the polarization at the mineral-fluid interface were converted to (1) estimated biomineral surface area to pore volume (Sp), and (2) an equivalent polarizable sphere diameter (d) controlling the relaxation time. The temporal variation in these model parameters is consistent with filling and emptying of pores by iron sulfide biofilms, as the system transitions between anaerobic (pore filling) and aerobic (pore emptying) conditions. The results suggest that combined SIP and electrodic potential measurements might be used to monitor spatiotemporal variability in microbial iron sulfide transformations in the field.

  16. Metal ion induced room temperature phase transformation and stimulated infrared spectroscopy on TiO{sub 2}-based surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Gole, James L. [Schools of Physics and Mechanical Engineering, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332-0430 (United States)], E-mail: jim.gole@physics.gatech.edu; Prokes, S.M. [Code 6876, NRL, Washington, DC 20375 (United States)], E-mail: prokes@estd.nrl.navy.mil; White, Mark G. [Dave C. Swalm School of Chemical Engineering, James Worth Bagley College of Engineering, Box 959, MS 39762 (United States)], E-mail: white@che.msstate.edu

    2008-11-30

    Raman and infrared spectroscopy are used to demonstrate (1) the high spin metal ion induced room temperature transformation of anatase to rutile TiO{sub 2} and (2) the phenomena of stimulated IR spectroscopy induced by simultaneous nitrogen doping and high spin metal ion seeding of a TiO{sub 2} nanocolloid lattice.

  17. Metal ion induced room temperature phase transformation and stimulated infrared spectroscopy on TiO2-based surfaces

    International Nuclear Information System (INIS)

    Gole, James L.; Prokes, S.M.; White, Mark G.

    2008-01-01

    Raman and infrared spectroscopy are used to demonstrate (1) the high spin metal ion induced room temperature transformation of anatase to rutile TiO 2 and (2) the phenomena of stimulated IR spectroscopy induced by simultaneous nitrogen doping and high spin metal ion seeding of a TiO 2 nanocolloid lattice

  18. Characterization of Transformation-Induced Defects in Nickel Titanium Shape Memory Alloys

    Science.gov (United States)

    Bowers, Matthew L.

    Shape memory alloys have remarkable strain recovery properties that make them ideal candidates for many applications that include devices in the automotive, aerospace, medical, and MEMS industries. Although these materials are widely used today, their performance is hindered by poor dimensional stability resulting from cyclic degradation of the martensitic transformation behavior. This functional fatigue results in decreased work output and cyclic accumulation of permanent strain. To date, few studies have taken a fundamental approach to investigating the interaction between plasticity and martensite growth and propagation, which is vitally important to mitigating functional fatigue in future alloy development. The current work focuses on understanding the interplay of these deformation mechanisms in NiTi-based shape memory alloys under a variety of different thermomechanical test conditions. Micron-scale compression testing of NiTi shape memory alloy single crystals is undertaken in an effort to probe the mechanism of austenite dislocation generation. Mechanical testing is paired with post mortem defect analysis via diffraction contrast scanning transmission electron microscopy (STEM). Accompanied by micromechanics-based modeling of local stresses surrounding a martensite plate, these results demonstrate that the previously existing martensite and resulting austenite dislocation substructure are intimately related. A mechanism of transformation-induced dislocation generation is described in detail. A study of pure and load-biased thermal cycling of bulk polycrystalline NiTi is done for comparison of the transformation behavior and resultant defects to the stress-induced case. Post mortem and in situ STEM characterization demonstrate unique defect configurations in this test mode and STEM-based orientation mapping reveals local crystal rotation with increasing thermal cycles. Changes in both martensite and austenite microstructures are explored. The results for

  19. Transforming growth factor β1 inhibition protects from noise-induced hearing loss

    Directory of Open Access Journals (Sweden)

    Silvia eMurillo-Cuesta

    2015-03-01

    Full Text Available Excessive exposure to noise damages the principal cochlear structures leading to hearing impairment. Inflammatory and immune responses are central mechanisms in cochlear defensive response to noise but, if unregulated, they contribute to inner ear damage and hearing loss. Transforming growth factor ß (TGF-ß is a key regulator of both responses and high levels of this factor have been associated with cochlear injury in hearing loss animal models. To evaluate the potential of targeting TGF-ß as a therapeutic strategy for preventing or ameliorating noise-induced hearing loss, we studied the auditory function, cochlear morphology, gene expression and oxidative stress markers in mice exposed to noise and treated with TGF-ß1 peptidic inhibitors P17 and P144, just before or immediately after noise insult. Our results indicate that systemic administration of both peptides significantly improved both the evolution of hearing thresholds and the degenerative changes induced by noise-exposure in lateral wall structures. Moreover, treatments ameliorated the inflammatory state and redox balance. These therapeutic effects were dose-dependent and more effective if the TGF-ß1 inhibitors were administered prior to inducing the injury. In conclusion, inhibition of TGF-ß1 actions with antagonistic peptides represents a new, promising therapeutic strategy for the prevention and repair of noise-induced cochlear damage.

  20. Ductile mandrel and parting compound facilitate tube drawing

    Science.gov (United States)

    Burt, W. R., Jr.; Mayfield, R. M.; Polakowski, N. H.

    1966-01-01

    Refractory tubing is warm drawn over a solid ductile mandrel with a powder parting compound packed between mandrel and the tubes inner surface. This method applies also to the coextrusion of a billet and a ductile mandrel.

  1. Comparative genome analysis of three eukaryotic parasites with differing abilities to transform leukocytes reveals key mediators of theileria-induced leukocyte transformation

    KAUST Repository

    Hayashida, Kyoko

    2012-09-04

    We sequenced the genome of Theileria orientalis, a tick-borne apicomplexan protozoan parasite of cattle. The focus of this study was a comparative genome analysis of T. orientalis relative to other highly pathogenic Theileria species, T. parva and T. annulata. T. parva and T. annulata induce transformation of infected cells of lymphocyte or macrophage/monocyte lineages; in contrast, T. orientalis does not induce uncontrolled proliferation of infected leukocytes and multiplies predominantly within infected erythrocytes. While synteny across homologous chromosomes of the three Theileria species was found to be well conserved overall, subtelomeric structures were found to differ substantially, as T. orientalis lacks the large tandemly arrayed subtelomere-encoded variable secreted protein-encoding gene family. Moreover, expansion of particular gene families by gene duplication was found in the genomes of the two transforming Theileria species, most notably, the TashAT/TpHN and Tar/Tpr gene families. Gene families that are present only in T. parva and T. annulata and not in T. orientalis, Babesia bovis, or Plasmo-dium were also identified. Identification of differences between the genome sequences of Theileria species with different abilities to transform and immortalize bovine leukocytes will provide insight into proteins and mechanisms that have evolved to induce and regulate this process. The T. orientalis genome database is available at http://totdb.czc.hokudai.ac.jp/. 2012 Hayashida et al. T.

  2. Ductile damage evolution and strain path dependency

    NARCIS (Netherlands)

    Tasan, C.C.; Hoefnagels, J.P.M.; Peerlings, R.H.J.; Geers, M.G.D.; Horn, ten C.H.L.J.; Vegter, H.; Cueto, E.; Chinesta, F.

    2007-01-01

    Forming limit diagrams are commonly used in sheet metal industry to define the safe forming regions. These diagrams are built to define the necking strains of sheet metals. However, with the rise in the popularity of advance high strength steels, ductile fracture through damage evolution has also

  3. General notes on ductility in timber structures

    NARCIS (Netherlands)

    Jorissen, A.J.M.; Fragiacomo, M.

    2011-01-01

    The paper discusses the implications of ductility in design of timber structures under static and dynamic loading including earthquakes. Timber is a material inherently brittle in bending and in tension, unless reinforced adequately. However connections between timber members can exhibit significant

  4. Ductile thermoset polymers via controlling network flexibility.

    Science.gov (United States)

    Hameed, N; Salim, N V; Walsh, T R; Wiggins, J S; Ajayan, P M; Fox, B L

    2015-06-18

    We report the design and synthesis of a polymer structure from a cross-linkable epoxy-ionic liquid system which behaves like a hard and brittle epoxy thermoset, perfectly ductile thermoplastic and an elastomer, all depending on controllable network compositions.

  5. A linear model of ductile plastic damage

    International Nuclear Information System (INIS)

    Lemaitre, J.

    1983-01-01

    A three-dimensional model of isotropic ductile plastic damage based on a continuum damage variable on the effective stress concept and on thermodynamics is derived. As shown by experiments on several metals and alloys, the model, integrated in the case of proportional loading, is linear with respect to the accumulated plastic strain and shows a large influence of stress triaxiality [fr

  6. Lunasin-aspirin combination against NIH/3T3 cells transformation induced by chemical carcinogens.

    Science.gov (United States)

    Hsieh, Chia-Chien; Hernández-Ledesma, Blanca; de Lumen, Ben O

    2011-06-01

    Carcinogenesis is a multistage process involving a number of molecular pathways sensitive to intervention. Chemoprevention is defined as the use of natural and/or synthetic substances to block, reverse, or retard the process of carcinogenesis. To achieve greater inhibitory effects on cancer cells, combination of two or more chemopreventive agents is commonly considered as a better preventive and/or therapeutic strategy. Lunasin is a promising cancer preventive peptide identified in soybean and other seeds. Its efficacy has been demonstrated by both in vitro and in vivo models. This peptide has been found to inhibit human breast cancer MDA-MB-231 cells proliferation, suppressing cell cycle progress and inducing cell apoptosis. Moreover, lunasin potentiates the effects on these cells of different synthetic and natural compounds, such as aspirin and anacardic acid. This study explored the role of lunasin, alone and in combination with aspirin and anacardic acid on cell proliferation and foci formation of transformed NIH/3T3 cells induced by chemical carcinogens 7,12-dimethylbenz[a]anthracene or 3-methylcholanthrene. The results revealed that lunasin, acting as a single agent, inhibits cell proliferation and foci formation. When combined with aspirin, these effects were significantly increased, indicating that this combination might be a promising strategy to prevent/treat cancer induced by chemical carcinogens.

  7. HPV-Induced Field Cancerisation: Transformation of Adult Tissue Stem Cell Into Cancer Stem Cell.

    Science.gov (United States)

    Olivero, Carlotta; Lanfredini, Simone; Borgogna, Cinzia; Gariglio, Marisa; Patel, Girish K

    2018-01-01

    Field cancerisation was originally described as a basis for multiple head and neck squamous cell carcinoma (HNSCC) and is a pre-malignant phenomenon that is frequently attributable to oncogenic human papillomavirus (HPV) infection. Our work on β-HPV-induced cutaneous squamous cell carcinomas identified a novel Lrig1+ hair follicle junctional zone keratinocyte stem cell population as the basis for field cancerisation. Herein, we describe the ability for HPV to infect adult tissue stem cells in order to establish persistent infection and induce their proliferation and displacement resulting in field cancerisation. By review of the HPV literature, we reveal how this mechanism is conserved as the basis of field cancerisation across many tissues. New insights have identified the capacity for HPV early region genes to dysregulate adult tissue stem cell self-renewal pathways ensuring that the expanded population preserve its stem cell characteristics beyond the stem cell niche. HPV-infected cells acquire additional transforming mutations that can give rise to intraepithelial neoplasia (IEN), from environmental factors such as sunlight or tobacco induced mutations in skin and oral cavity, respectively. With establishment of IEN, HPV viral replication is sacrificed with loss of the episome, and the tissue is predisposed to multiple cancer stem cell-driven carcinomas.

  8. CF3DODA-Me induces apoptosis, degrades Sp1, and blocks the transformation phase of the blebbishield emergency program.

    Science.gov (United States)

    Taoka, Rikiya; Jinesh, Goodwin G; Xue, Wenrui; Safe, Stephen; Kamat, Ashish M

    2017-05-01

    Cancer stem cells are capable of undergoing cellular transformation after commencement of apoptosis through the blebbishield emergency program in a VEGF-VEGFR2-dependent manner. Development of therapeutics targeting the blebbishield emergency program would thus be important in cancer therapy. Specificity protein 1 (Sp1) orchestrates the transcription of both VEGF and VEGFR2; hence, Sp1 could act as a therapeutic target. Here, we demonstrate that CF 3 DODA-Me induced apoptosis, degraded Sp1, inhibited the expression of multiple drivers of the blebbishield emergency program such as VEGFR2, p70S6K, and N-Myc through activation of caspase-3, inhibited reactive oxygen species; and inhibited K-Ras activation to abolish transformation from blebbishields as well as transformation in soft agar. These findings confirm CF 3 DODA-Me as a potential therapeutic candidate that can induce apoptosis and block transformation from blebbishields.

  9. Stress-induced martensitic transformations in NiTi and NiTi-TiC composites investigated by neutron diffraction

    International Nuclear Information System (INIS)

    Vaidyanathan, R.; Dunand, D.C.

    1999-01-01

    Superelastic NiTi (51.0 at.% Ni) specimens reinforced with 0, 10 and 20 vol.% TiC particles were deformed under uniaxial compression while neutron diffraction spectra were collected. The experiments yielded in-situ measurements of the thermoelastic stress-induced transformation. The evolution of austenite/martensite phase fractions and of elastic strains in the reinforcing TiC particles and the austenite matrix were obtained by Rietveld refinement during the loading cycle as the austenite transforms to martensite (and its subsequent back transformation during unloading). Phase fractions and strains are discussed in terms of load transfer in composites where the matrix undergoes a stress-induced phase transformation. (orig.)

  10. Analysis of nucleation modelling in ductile cast iron

    DEFF Research Database (Denmark)

    Moumeni, Elham; Tutum, Cem Celal; Tiedje, Niels Skat

    2012-01-01

    Heterogeneous nucleation of nodular graphite at inclusions in ductile iron during eutectic solidification has been investigated. The experimental part of this work deals with casting of ductile iron samples with two different inoculants in four different thicknesses. Chemical analysis, metallogra......Heterogeneous nucleation of nodular graphite at inclusions in ductile iron during eutectic solidification has been investigated. The experimental part of this work deals with casting of ductile iron samples with two different inoculants in four different thicknesses. Chemical analysis...

  11. Synchrotron measurements of local microstructure and residual strains in ductile cast iron

    DEFF Research Database (Denmark)

    Zhang, Yubin; Andriollo, Tito; Fæster, Søren

    2017-01-01

    The local microstructure and distribution of thermally induced residual strains in ferrite matrix grains around an individual spherical graphite nodule in ductile cast iron (DCI) were measured using a synchrotron X-ray micro-diffraction technique. It is found that the matrix grains are deformed...

  12. Analysis of copper contamination in transformer insulating material with nanosecond- and femtosecond-laser-induced breakdown spectroscopy

    Science.gov (United States)

    Aparna, N.; Vasa, N. J.; Sarathi, R.

    2018-06-01

    This work examines the oil-impregnated pressboard insulation of high-voltage power transformers, for the determination of copper contamination. Nanosecond- and femtosecond-laser-induced breakdown spectroscopy revealed atomic copper lines and molecular copper monoxide bands due to copper sulphide diffusion. X-ray diffraction studies also indicated the presence of CuO emission. Elemental and molecular mapping compared transformer insulating material ageing in different media—air, N2, He and vacuum.

  13. Mycobacteria exploit nitric oxide-induced transformation of macrophages into permissive giant cells.

    Science.gov (United States)

    Gharun, Kourosh; Senges, Julia; Seidl, Maximilian; Lösslein, Anne; Kolter, Julia; Lohrmann, Florens; Fliegauf, Manfred; Elgizouli, Magdeldin; Vavra, Martina; Schachtrup, Kristina; Illert, Anna L; Gilleron, Martine; Kirschning, Carsten J; Triantafyllopoulou, Antigoni; Henneke, Philipp

    2017-12-01

    Immunity to mycobacteria involves the formation of granulomas, characterized by a unique macrophage (MΦ) species, so-called multinucleated giant cells (MGC). It remains unresolved whether MGC are beneficial to the host, that is, by prevention of bacterial spread, or whether they promote mycobacterial persistence. Here, we show that the prototypical antimycobacterial molecule nitric oxide (NO), which is produced by MGC in excessive amounts, is a double-edged sword. Next to its antibacterial capacity, NO propagates the transformation of MΦ into MGC, which are relatively permissive for mycobacterial persistence. The mechanism underlying MGC formation involves NO-induced DNA damage and impairment of p53 function. Moreover, MGC have an unsurpassed potential to engulf mycobacteria-infected apoptotic cells, which adds a further burden to their antimycobacterial capacity. Accordingly, mycobacteria take paradoxical advantage of antimicrobial cellular efforts by driving effector MΦ into a permissive MGC state. © 2017 The Authors.

  14. Hydrogen Induced Crack and Phase Transformation in Hydrogen Pressured Tensile Test of 316L Stainless Steel

    Energy Technology Data Exchange (ETDEWEB)

    Baek, Un Bong; Nam, Sung Hoon [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of); Choe, Byung Hak; Shim, Jong Hun [Gangneung-Wonju National University, Gangneung (Korea, Republic of); Kim, Young Uk [Hanyang University, Ansan (Korea, Republic of); Kim, Young Suk; Kim, Sung Soo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Hong, Keyyong [Korea Research Institute of Ship and Ocean Engineering, Deajeon (Korea, Republic of)

    2015-02-15

    The aim of this investigation is to prove the mechanism of hydrogen induced crack (HIC) of 316L stainless steels in hydrogen pressured tensile test. Microstructures like twin, planar slip, and abnormal phase transformation around the HIC were analyzed by transmission electron microscopy. Deformation twin accompanied by planar slip could be related to the main cause of HIC in the hydrogen pressured tensile condition, because intragranular HICs were mainly observed along the boundaries of twins and planar slip lines. An abnormal forbidden diffraction was also accompanied by HIC in the hydrogen attacked area. Examination of the HIC mechanism in austenitic stainless steel can be applied to the fitness of use for alloys with the possibility of various susceptible cracks in a hydrogen and stress atmosphere.

  15. Suppression of SOS-inducing activity of chemical mutagens by metabolites from microbial transformation of (-)-isolongifolene.

    Science.gov (United States)

    Sakata, Kazuki; Oda, Yoshimitsu; Miyazawa, Mitsuo

    2010-02-24

    In this study, biotransformation of (-)-isolongifolene (1) by Glomerella cingulata and suppressive effect on umuC gene expression by chemical mutagens 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (furylfuramide) and aflatoxin B(1) (AFB(1)) of the SOS response in Salmonella typhimurium TA1535/pSK1002 were investigated. Initially, 1 was carried out the microbial transformation by G. cingulata. The result found that 1 was converted into (-)-isolongifolen-9-one (2), (-)-(2S)-13-hydroxy-isolongifolen-9-one (3), and (-)-(4R)-4-hydroxy-isolongifolen-9-one (4) by G. cingulata, and their conversion rates were 60, 25, and 15%, respectively. The metabolites suppressed the SOS-inducing activity of furylfuramid and AFB(1) in the umu test. Comound 2 showed gene expression by chemical mutagens furylfuramide and AFB(1) was suppressed 54 and 50% at <0.5 mM, respectively. Compound 2 is the most effective compound in this experiment.

  16. Martensitic phase transformations in the nanostructured surface layers induced by mechanical attrition treatment

    International Nuclear Information System (INIS)

    Ni Zhichun; Wang Xiaowei; Wu Erdong; Liu Gang

    2005-01-01

    Conversion electron Moessbauer spectroscopy (CEMS) and x-ray diffraction (XRD) analysis have been used to investigate the relationship between characteristics of phase transformation and the treatment time in surface nanocrystallized 316L stainless steel induced by surface mechanical attrition treatment (SMAT). A similar trend of development of the martensitic phase upon the treatment time has been observed from both CEMS and XRD measurements. However, in the CEMS measurement, two types of martensite phase with different magnetic hyperfine fields are revealed. Based on a random distribution of the non-iron coordinating atoms, a three-element theoretical model is developed to illustrate the difference of two types of martensite phase. The calculated results indicate the segregation of the non-iron atoms associated with SMAT treatment

  17. Nucleation in stress-induced tetragonal-monoclinic transformation of constrained zirconia

    International Nuclear Information System (INIS)

    Chan, S.K.

    1992-08-01

    A theory for stress-induced tetragonal→monoclinic transformation of constrained zirconia is presented based on the assumption that when forcibly strained to a regime of absolute instability where the free energy density of the tetragonal phase has a negative curvature, the constrained tetragonal zirconia becomes unstable with respect to the development of a modulated strain pattern that will evolve into a band of twin monoclinic domains. The temperature range for such an instability, the critical size of the inclusion, the corresponding critical strain, and the periodicity of the modulation are derived in terms of parameters that can be related to the elastic stiffness coefficients of various orders of the inclusion and the shear modulus of the host matrix. An entirely different mechanism is suggested for the reverse monoclinic→tetragonal transformation because the monoclinic phase is metastable when the extrinsic stress is removed. Estimates for the parameters are inferred from a variety of experimental data for pure zirconia and the numerical values for the predicted physical quantities are obtained

  18. Phase transformations in a Cu−Cr alloy induced by high pressure torsion

    International Nuclear Information System (INIS)

    Korneva, Anna; Straumal, Boris; Kilmametov, Askar; Chulist, Robert; Straumal, Piotr; Zięba, Paweł

    2016-01-01

    Phase transformations induced by high pressure torsion (HPT) at room temperature in two samples of the Cu-0.86 at.% Cr alloy, pre-annealed at 550 °C and 1000 °C, were studied in order to obtain two different initial states for the HPT procedure. Observation of microstructure of the samples before HPT revealed that the sample annealed at 550 °C contained two types of Cr precipitates in the Cu matrix: large particles (size about 500 nm) and small ones (size about 70 nm). The sample annealed at 1000 °C showed only a little fraction of Cr precipitates (size about 2 μm). The subsequent HPT process resulted in the partial dissolution of Cr precipitates in the first sample and dissolution of Cr precipitates with simultaneous decomposition of the supersaturated solid solution in another. However, the resulting microstructure of the samples after HPT was very similar from the standpoint of grain size, phase composition, texture analysis and hardness measurements. - Highlights: • Cu−Cr alloy with two different initial states was deformed by HPT. • Phase transformations in the deformed materials were studied. • SEM, TEM and X-ray diffraction techniques were used for microstructure analysis. • HPT leads to formation the same microstructure independent of the initial state.

  19. Characterization of carbon ion implantation induced graded microstructure and phase transformation in stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Kai; Wang, Yibo [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Li, Zhuguo, E-mail: lizg@sjtu.edu.cn [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2015-08-15

    Austenitic stainless steel 316L is ion implanted by carbon with implantation fluences of 1.2 × 10{sup 17} ions-cm{sup −} {sup 2}, 2.4 × 10{sup 17} ions-cm{sup −} {sup 2}, and 4.8 × 10{sup 17} ions-cm{sup −} {sup 2}. The ion implantation induced graded microstructure and phase transformation in stainless steel is investigated by X-ray diffraction, X-ray photoelectron spectroscopy and high resolution transmission electron microscopy. The corrosion resistance is evaluated by potentiodynamic test. It is found that the initial phase is austenite with a small amount of ferrite. After low fluence carbon ion implantation, an amorphous layer and ferrite phase enriched region underneath are formed. Nanophase particles precipitate from the amorphous layer due to energy minimization and irradiation at larger ion implantation fluence. The morphology of the precipitated nanophase particles changes from circular to dumbbell-like with increasing implantation fluence. The corrosion resistance of stainless steel is enhanced by the formation of amorphous layer and graphitic solid state carbon after carbon ion implantation. - Highlights: • Carbon implantation leads to phase transformation from austenite to ferrite. • The passive film on SS316L becomes thinner after carbon ion implantation. • An amorphous layer is formed by carbon ion implantation. • Nanophase precipitate from amorphous layer at higher ion implantation fluence. • Corrosion resistance of SS316L is improved by carbon implantation.

  20. MCD-induced steatohepatitis is associated with hepatic adiponectin resistance and adipogenic transformation of hepatocytes.

    Science.gov (United States)

    Larter, Claire Z; Yeh, Matthew M; Williams, Jacqueline; Bell-Anderson, Kim S; Farrell, Geoffrey C

    2008-09-01

    In these studies, we tested the hypothesis that increased lipid intake would exacerbate the severity of nutritional steatohepatitis. C57Bl/6J mice were fed methionine-and-choline deficient (MCD) diets containing 20% (high) or 5% (low) fat by weight for 3 weeks and compared to lipid-matched controls. MCD feeding increased serum ALT levels and induced hepatic steatosis, lobular inflammation and ballooning degeneration of hepatocytes, irrespective of dietary fat content. Hepatic triglyceride accumulation was similar between high and low-fat MCD-fed mice, but lipoperoxide levels were approximately 3-fold higher in the high-fat MCD-fed animals. Serum adiponectin levels increased in MCD-fed mice, although to a lesser extent in high-fat fed animals. AMPK phosphorylation was correspondingly increased in muscle of MCD-fed mice, but hepatic AMPK phosphorylation decreased, and there was little evidence of PPAR alpha activation, suggesting impaired adiponectin action in the livers of MCD-fed animals. Hepatocyte PPAR gamma mRNA levels increased in MCD-fed mice, and were associated with increased aP2 expression, indicating adipogenic transformation of hepatocytes. Increased dietary lipid intake did not alter steatohepatitis severity in MCD-fed mice despite increased lipoperoxide accumulation. Instead, steatohepatitis was associated with impaired hepatic adiponectin action, and adipogenic transformation of hepatocytes in both low and high-fat MCD-fed mice.

  1. Arsenite induces cell transformation by reactive oxygen species, AKT, ERK1/2, and p70S6K1

    International Nuclear Information System (INIS)

    Carpenter, Richard L.; Jiang, Yue; Jing, Yi; He, Jun; Rojanasakul, Yon; Liu, Ling-Zhi; Jiang, Bing-Hua

    2011-01-01

    Highlights: ► Chronic exposure to arsenite induces cell proliferation and transformation. ► Arsenite-induced transformation increases ROS production and downstream signalings. ► Inhibition of ROS levels via catalase reduces arsenite-induced cell transformation. ► Interruption of AKT, ERK, or p70S6K1 inhibits arsenite-induced cell transformation. -- Abstract: Arsenic is naturally occurring element that exists in both organic and inorganic formulations. The inorganic form arsenite has a positive association with development of multiple cancer types. There are significant populations throughout the world with high exposure to arsenite via drinking water. Thus, human exposure to arsenic has become a significant public health problem. Recent evidence suggests that reactive oxygen species (ROS) mediate multiple changes to cell behavior after acute arsenic exposure, including activation of proliferative signaling and angiogenesis. However, the role of ROS in mediating cell transformation by chronic arsenic exposure is unknown. We found that cells chronically exposed to sodium arsenite increased proliferation and gained anchorage-independent growth. This cell transformation phenotype required constitutive activation of AKT, ERK1/2, mTOR, and p70S6K1. We also observed these cells constitutively produce ROS, which was required for the constitutive activation of AKT, ERK1/2, mTOR, and p70S6K1. Suppression of ROS levels by forced expression of catalase also reduced cell proliferation and anchorage-independent growth. These results indicate cell transformation induced by chronic arsenic exposure is mediated by increased cellular levels of ROS, which mediates activation of AKT, ERK1/2, and p70S6K1.

  2. Ductile fracture surface morphology of amorphous metallic alloys

    NARCIS (Netherlands)

    Miskuf, J; Csach, K; Ocelik, [No Value; Bengus, VZ; Tabachnikova, ED; Duhaj, P; Ocelik, Vaclav

    1999-01-01

    Fracture surfaces of ductile failure of two types bulk amorphous metallic alloys were studied using quantitative and qualitative fractographic analysis. The observed fractographic behaviour of ductile failure in comparison with the ductile failure of amorphous alloy ribbons shows signs of the same

  3. Ductile and brittle transition behavior of titanium alloys in ultra-precision machining.

    Science.gov (United States)

    Yip, W S; To, S

    2018-03-02

    Titanium alloys are extensively applied in biomedical industries due to their excellent material properties. However, they are recognized as difficult to cut materials due to their low thermal conductivity, which induces a complexity to their deformation mechanisms and restricts precise productions. This paper presents a new observation about the removal regime of titanium alloys. The experimental results, including the chip formation, thrust force signal and surface profile, showed that there was a critical cutting distance to achieve better surface integrity of machined surface. The machined areas with better surface roughness were located before the clear transition point, defining as the ductile to brittle transition. The machined area at the brittle region displayed the fracture deformation which showed cracks on the surface edge. The relationship between depth of cut and the ductile to brittle transaction behavior of titanium alloys in ultra-precision machining(UPM) was also revealed in this study, it showed that the ductile to brittle transaction behavior of titanium alloys occurred mainly at relatively small depth of cut. The study firstly defines the ductile to brittle transition behavior of titanium alloys in UPM, contributing the information of ductile machining as an optimal machining condition for precise productions of titanium alloys.

  4. TAL effector nucleases induce mutations at a pre-selected location in the genome of primary barley transformants

    DEFF Research Database (Denmark)

    Wendt, Toni; Holm, Preben Bach; Starker, Colby G

    2013-01-01

    , and their broad targeting range. Here we report the assembly of several TALENs for a specific genomic locus in barley. The cleavage activity of individual TALENs was first tested in vivo using a yeast-based, single-strand annealing assay. The most efficient TALEN was then selected for barley transformation....... Analysis of the resulting transformants showed that TALEN-induced double strand breaks led to the introduction of short deletions at the target site. Additional analysis revealed that each barley transformant contained a range of different mutations, indicating that mutations occurred independently...

  5. Effect of prestrain on ductility and toughness in high strength line pipe steels

    Energy Technology Data Exchange (ETDEWEB)

    Shinohara, Y.; Besson, J. [Paristech, Evry (France). Centre des Materiaux, Mines Paris; Madi, Y. [Ecole d' Ingenieurs, Sceaux (France). Ermess EPF; Paristech, Evry (France). Centre des Materiaux, Mines Paris

    2009-07-01

    The anisotropic plasticity, ductility and toughness of an X100 steel pipeline was investigated both before and after a series of prestraining experiments. The aim of the study was to determine the effect of prestraining on ductility and toughness in high strength pipe steels. Results of the study showed that primary void growth and coalescence was dependent on initial plastic anisotropy and not dependent on tensile prestrain. Secondary void nucleation and growth was not influenced by either the initial plastic anisotropy or by prestraining. Scanning electron microscopy (SEM) studies showed that the main damage mechanism was the void growth of primary dimples. Dimples in the prestrained materials were larger than those observed in materials that had not been prestrained. However, the effect on prestrain on dimple size was limited. Results showed both plastic and rupture anisotropies. It was concluded that prestraining induces a decrease in ductility, but has a significant impact on toughness. 4 refs., 2 tabs., 12 figs.

  6. Serotonin potentiates transforming growth factor-beta3 induced biomechanical remodeling in avian embryonic atrioventricular valves.

    Directory of Open Access Journals (Sweden)

    Philip R Buskohl

    Full Text Available Embryonic heart valve primordia (cushions maintain unidirectional blood flow during development despite an increasingly demanding mechanical environment. Recent studies demonstrate that atrioventricular (AV cushions stiffen over gestation, but the molecular mechanisms of this process are unknown. Transforming growth factor-beta (TGFβ and serotonin (5-HT signaling modulate tissue biomechanics of postnatal valves, but less is known of their role in the biomechanical remodeling of embryonic valves. In this study, we demonstrate that exogenous TGFβ3 increases AV cushion biomechanical stiffness and residual stress, but paradoxically reduces matrix compaction. We then show that TGFβ3 induces contractile gene expression (RhoA, aSMA and extracellular matrix expression (col1α2 in cushion mesenchyme, while simultaneously stimulating a two-fold increase in proliferation. Local compaction increased due to an elevated contractile phenotype, but global compaction appeared reduced due to proliferation and ECM synthesis. Blockade of TGFβ type I receptors via SB431542 inhibited the TGFβ3 effects. We next showed that exogenous 5-HT does not influence cushion stiffness by itself, but synergistically increases cushion stiffness with TGFβ3 co-treatment. 5-HT increased TGFβ3 gene expression and also potentiated TGFβ3 induced gene expression in a dose-dependent manner. Blockade of the 5HT2b receptor, but not 5-HT2a receptor or serotonin transporter (SERT, resulted in complete cessation of TGFβ3 induced mechanical strengthening. Finally, systemic 5-HT administration in ovo induced cushion remodeling related defects, including thinned/atretic AV valves, ventricular septal defects, and outflow rotation defects. Elevated 5-HT in ovo resulted in elevated remodeling gene expression and increased TGFβ signaling activity, supporting our ex-vivo findings. Collectively, these results highlight TGFβ/5-HT signaling as a potent mechanism for control of biomechanical

  7. Stress- and Magnetic Field-Induced Martensitic Transformation at Cryogenic Temperatures in Fe-Mn-Al-Ni Shape Memory Alloys

    Science.gov (United States)

    Xia, Ji; Xu, Xiao; Miyake, Atsushi; Kimura, Yuta; Omori, Toshihiro; Tokunaga, Masashi; Kainuma, Ryosuke

    2017-12-01

    Stress-induced and magnetic-field-induced martensitic transformation behaviors at low temperatures were investigated for Fe-Mn-Al-Ni alloys. The magnetic-field-induced reverse martensitic transformation was directly observed by in situ optical microscopy. Magnetization measurements under pulsed magnetic fields up to 50 T were carried out at temperatures between 4.2 and 125 K on a single-crystal sample; full magnetic-field-induced reverse martensitic transformation was confirmed at all tested temperatures. Compression tests from 10 to 100 K were conducted on a single-crystal sample; full shape recovery was obtained at all tested temperatures. It was found that the temperature dependence of both the critical stress and critical magnetic field is small and that the transformation hysteresis is less sensitive to temperature even at cryogenic temperatures. The temperature dependence of entropy change during martensitic transformation up to 100 K was then derived using the Clausius-Clapeyron relation with critical stresses and magnetic fields.

  8. Effect of lattice mismatch-induced strains on coupled diffusive and displacive phase transformations

    OpenAIRE

    Bouville, Mathieu; Ahluwalia, Rajeev

    2006-01-01

    Materials which can undergo slow diffusive transformations as well as fast displacive transformations are studied using the phase-field method. The model captures the essential features of the time-temperature-transformation (TTT) diagrams, continuous cooling transformation (CCT) diagrams, and microstructure formation of these alloys. In some materials systems there can exist an intrinsic volume change associated with these transformations. We show that these coherency strains can stabilize m...

  9. Transformations of visual memory induced by implied motions of pattern elements.

    Science.gov (United States)

    Finke, R A; Freyd, J J

    1985-10-01

    Four experiments measured distortions in short-term visual memory induced by displays depicting independent translations of the elements of a pattern. In each experiment, observers saw a sequence of 4 dot patterns and were instructed to remember the third pattern and to compare it with the fourth. The first three patterns depicted translations of the dots in consistent, but separate directions. Error rates and reaction times for rejecting the fourth pattern as different from the third were substantially higher when the dots in that pattern were displaced slightly forward, in the same directions as the implied motions, compared with when the dots were displaced in the opposite, backward directions. These effects showed little variation across interstimulus intervals ranging from 250 to 2,000 ms, and did not depend on whether the displays gave rise to visual apparent motion. However, they were eliminated when the dots in the fourth pattern were displaced by larger amounts in each direction, corresponding to the dot positions in the next and previous patterns in the same inducing sequence. These findings extend our initial report of the phenomenon of "representational momentum" (Freyd & Finke, 1984a), and help to rule out alternatives to the proposal that visual memories tend to undergo, at least to some extent, the transformations implied by a prior sequence of observed events.

  10. Transforming growth factor-β2 induces morphological alteration of human corneal endothelial cells in vitro

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2014-10-01

    Full Text Available AIM:To investigate the morphological altering effect of transforming growth factor-β2 (TGF-β2 on untransfected human corneal endothelial cells (HCECs in vitro.METHODS: After untransfected HCECs were treated with TGF-β2 at different concentrations, the morphology, cytoskeleton distribution, and type IV collagen expression of the cells were examined with inverted contrast light microscopy, fluorescence microscopy, immunofluorescence or Western Blot.RESULTS:TGF-β2 at the concentration of 3-15 μg/L had obviously alterative effects on HCECs morphology in dose and time-dependent manner, and 9 μg/L was the peak concentration. TGF-β2 (9 μg/L altered HCE cell morphology after treatment for 36h, increased the mean optical density (P<0.01 and the length of F-actin, reduced the mean optical density (P<0.01 of the collagen type IV in extracellular matrix (ECM and induced the rearrangement of F-actin, microtubule in cytoplasm and collagen type IV in ECM after treatment for 72h. CONCLUTION:TGF-β2 has obviously alterative effect on the morphology of HCECs from polygonal phenotype to enlarged spindle-shaped phenotype, in dose and time-dependence manner by inducing more, elongation and alignment of F-actin, rearrangement of microtubule and larger spread area of collagen type IV.

  11. Suppression of nanoindentation-induced phase transformation in crystalline silicon implanted with hydrogen

    Science.gov (United States)

    Jelenković, Emil V.; To, Suet

    2017-09-01

    In this paper the effect of hydrogen implantation in silicon on nanoindentation-induced phase transformation is investigated. Hydrogen ions were implanted in silicon through 300 nm thick oxide with double energy implantation (75 and 40 keV). For both energies implantation dose was 4 × 1016 cm-2. Some samples were thermally annealed at 400 °C. The micro-Raman spectroscopy was applied on nanoindentation imprints and the obtained results were related to the pop out/elbow appearances in nanoindentatioin unloading-displacement curves. The Raman spectroscopy revealed a suppression of Si-XII and Si-III phases and formation of a-Si in the indents of hydrogen implanted Si. The high-resolution x-ray diffraction measurements were taken to support the analysis of silicon phase formation during nanoindentation. Implantation induced strain, high hydrogen concentration, and platelets generation were found to be the factors that control suppression of c-Si phases Si-XII and Si-III, as well as a-Si phase enhancement during nanoindentation. [Figure not available: see fulltext.

  12. The Rheological Evolution of Brittle-Ductile Transition Rocks During the Earthquake Cycle: Evidence for a Ductile Precursor to Pseudotachylyte in an Extensional Fault System, South Mountains, Arizona

    Science.gov (United States)

    Stewart, Craig A.; Miranda, Elena A.

    2017-12-01

    We investigate how the rheological evolution of shear zone rocks from beneath the brittle-ductile transition (BDT) is affected by coeval ductile shear and pseudotachylyte development associated with seismicity during the earthquake cycle. We focus our study on footwall rocks of the South Mountains core complex, and we use electron backscatter diffraction (EBSD) analyses to examine how strain is localized in granodiorite mylonites both prior to and during pseudotachylyte development beneath the BDT. In mylonites that are host to pseudotachylytes, deformation is partitioned into quartz, where quartz exhibits crystallographic-preferred orientation patterns and microstructures indicative of dynamic recrystallization during dislocation creep. Grain size reduction during dynamic recrystallization led to the onset of grain boundary sliding (GBS) accommodated by fluid-assisted grain size-sensitive (GSS) creep, localizing strain in quartz-rich layers prior to pseudotachylyte development. The foliation-parallel zones of GBS in the host mylonites, and the presence of GBS traits in polycrystalline quartz survivor clasts indicate that GBS zones were the ductile precursors to in situ pseudotachylyte generation. During pseudotachylyte development, strain was partitioned into the melt phase, and GSS deformation in the survivor clasts continued until crystallization of melt impeded flow, inducing pseudotachylyte development in other GBS zones. We interpret the coeval pseudotachylytes with ductile precursors as evidence of seismic events near the BDT. Grain size piezometry yields high differential stresses in both host mylonites ( 160 MPa) and pseudotachylyte survivor clasts (> 200 MPa), consistent with high stresses during interseismic and coseismic phases of the earthquake cycle, respectively.

  13. Neuropilin-2 induced by transforming growth factor-β augments migration of hepatocellular carcinoma cells

    International Nuclear Information System (INIS)

    Wittmann, Philipp; Grubinger, Markus; Gröger, Christian; Huber, Heidemarie; Sieghart, Wolfgang; Peck-Radosavljevic, Markus; Mikulits, Wolfgang

    2015-01-01

    Hepatocellular carcinoma (HCC) is the most common form of liver cancer and the third most lethal cancer worldwide. The epithelial to mesenchymal transition (EMT) describes the transformation of well-differentiated epithelial cells to a de-differentiated phenotype and plays a central role in the invasion and intrahepatic metastasis of HCC cells. Modulation of the transforming growth factor-β (TGF-β) signaling is known to induce various tumor-promoting and EMT-inducing pathways in HCC. The meta-analysis of a panel of EMT gene expression studies revealed that neuropilin 2 (NRP2) is significantly upregulated in cells that have undergone EMT induced by TGF-β. In this study we assessed the functional role of NRP2 in epithelial and mesenchymal-like HCC cells and focused on the molecular interplay between NRP2 and TGF-β/Smad signaling. NRP2 expression was analyzed in human HCC cell lines and tissue arrays comprising 133 HCC samples. Cell migration was examined by wound healing and Transwell assays in the presence and absence of siRNA against NRP2. NRP2 and TGF-β signaling were analyzed by Western blotting and confocal immunofluorescence microscopy. We show that NRP2 is particularly expressed in HCC cell lines with a dedifferentiated, mesenchymal-like phenotype. NRP2 expression is upregulated by the canonical TGF-β/Smad signaling while NRP2 expression has no impact on TGF-β signaling in HCC cells. Reduced expression of NRP2 by knock-down or inhibition of TGF-β signaling resulted in diminished cell migration independently of each other, suggesting that NRP2 fails to collaborate with TGF-β signaling in cell movement. In accordance with these data, elevated levels of NRP2 correlated with a higher tumor grade and less differentiation in a large collection of human HCC specimens. These data suggest that NRP2 associates with a less differentiated, mesenchymal-like HCC phenotype and that NRP2 plays an important role in tumor cell migration upon TGF-β-dependent HCC

  14. Mechanisms and mechanics of porosity formation in ductile iron castings

    Directory of Open Access Journals (Sweden)

    M. Perzyk

    2007-12-01

    Full Text Available Shrinkage defects in ductile iron castings can be of two basic types: shrinkage cavities associated with the liquid contraction prior to the expansion period of the iron as well as the porosity, which may appear even if the liquid shrinkage is fully compensated. In the present paper two possible mechanisms of the porosity are presented and analyzed. The first one is the Karsay’s mechanism based on the secondary shrinkage concept. The second one is the mechanism acting during the expansion period of the iron, first suggested by Ohnaka and co-authors and essentially modified by the present authors. The mechanical interactions between casting and mould are determined for the both mechanisms. Their analysis leads to the conclusion, that porosity forms during expansion period of the melt. The direct cause is the negative pressure which appears in the central part of the casting due to the differences in expansion coefficients of the fast cooling surface layer and slow cooling inner region. Observations concerning feeding behavior of ductile iron castings, based on this mechanism, agree well with industrial practice. The secondary shrinkage is not only needless to induce the porosity, but the corresponding mechanism of its occurrence, proposed by Karsay, does not seem to be valid.

  15. Anisotropic Constitutive Model of Strain-induced Phenomena in Stainless Steels at Cryogenic Temperatures

    CERN Document Server

    Garion, C

    2004-01-01

    A majority of the thin-walled components subjected to intensive plastic straining at cryogenic temperatures are made of stainless steels. The examples of such components can be found in the interconnections of particle accelerators, containing the superconducting magnets, where the thermal contraction is absorbed by thin-walled, axisymetric shells called bellows expansion joints. The stainless steels show three main phenomena induced by plastic strains at cryogenic temperatures: serrated (discontinuous) yielding, gamma->alpha' phase transformation and anisotropic ductile damage. In the present paper, a coupled constitutive model of gamma->alpha' phase transformation and orthotropic ductile damage is presented. A kinetic law of phase transformation, and a kinetic law of evolution of orthotropic damage are presented. The model is extended to anisotropic plasticity comprising a constant anisotropy (texture effect), which can be classically taken into account by the Hill yield surface, and plastic strain induced ...

  16. A review on ductile mode cutting of brittle materials

    Science.gov (United States)

    Antwi, Elijah Kwabena; Liu, Kui; Wang, Hao

    2018-06-01

    Brittle materials have been widely employed for industrial applications due to their excellent mechanical, optical, physical and chemical properties. But obtaining smooth and damage-free surface on brittle materials by traditional machining methods like grinding, lapping and polishing is very costly and extremely time consuming. Ductile mode cutting is a very promising way to achieve high quality and crack-free surfaces of brittle materials. Thus the study of ductile mode cutting of brittle materials has been attracting more and more efforts. This paper provides an overview of ductile mode cutting of brittle materials including ductile nature and plasticity of brittle materials, cutting mechanism, cutting characteristics, molecular dynamic simulation, critical undeformed chip thickness, brittle-ductile transition, subsurface damage, as well as a detailed discussion of ductile mode cutting enhancement. It is believed that ductile mode cutting of brittle materials could be achieved when both crack-free and no subsurface damage are obtained simultaneously.

  17. Nanowire failure: long = brittle and short = ductile.

    Science.gov (United States)

    Wu, Zhaoxuan; Zhang, Yong-Wei; Jhon, Mark H; Gao, Huajian; Srolovitz, David J

    2012-02-08

    Experimental studies of the tensile behavior of metallic nanowires show a wide range of failure modes, ranging from ductile necking to brittle/localized shear failure-often in the same diameter wires. We performed large-scale molecular dynamics simulations of copper nanowires with a range of nanowire lengths and provide unequivocal evidence for a transition in nanowire failure mode with change in nanowire length. Short nanowires fail via a ductile mode with serrated stress-strain curves, while long wires exhibit extreme shear localization and abrupt failure. We developed a simple model for predicting the critical nanowire length for this failure mode transition and showed that it is in excellent agreement with both the simulation results and the extant experimental data. The present results provide a new paradigm for the design of nanoscale mechanical systems that demarcates graceful and catastrophic failure. © 2012 American Chemical Society

  18. A review of macroscopic ductile failure criteria.

    Energy Technology Data Exchange (ETDEWEB)

    Corona, Edmundo; Reedlunn, Benjamin

    2013-09-01

    The objective of this work was to describe several of the ductile failure criteria com- monly used to solve practical problems. The following failure models were considered: equivalent plastic strain, equivalent plastic strain in tension, maximum shear, Mohr- Coulomb, Wellman's tearing parameter, Johnson-Cook and BCJ MEM. The document presents the main characteristics of each failure model as well as sample failure predic- tions for simple proportional loading stress histories in three dimensions and in plane stress. Plasticity calculations prior to failure were conducted with a simple, linear hardening, J2 plasticity model. The resulting failure envelopes were plotted in prin- cipal stress space and plastic strain space, where the dependence on stress triaxiality and Lode angle are clearly visible. This information may help analysts select a ductile fracture model for a practical problem and help interpret analysis results.

  19. Prediction of Ductile Fracture Surface Roughness Scaling

    DEFF Research Database (Denmark)

    Needleman, Alan; Tvergaard, Viggo; Bouchaud, Elisabeth

    2012-01-01

    . Ductile crack growth in a thin strip under mode I, overall plane strain, small scale yielding conditions is analyzed. Although overall plane strain loading conditions are prescribed, full 3D analyses are carried out to permit modeling of the three dimensional material microstructure and of the resulting......Experimental observations have shown that the roughness of fracture surfaces exhibit certain characteristic scaling properties. Here, calculations are carried out to explore the extent to which a ductile damage/fracture constitutive relation can be used to model fracture surface roughness scaling...... three dimensional stress and deformation states that develop in the fracture process region. An elastic-viscoplastic constitutive relation for a progressively cavitating plastic solid is used to model the material. Two populations of second phase particles are represented: large inclusions with low...

  20. Fuel powder production from ductile uranium alloys

    International Nuclear Information System (INIS)

    Clark, C.R.; Meyer, M.K.

    1998-01-01

    Metallic uranium alloys are candidate materials for use as the fuel phase in very-high-density LEU dispersion fuels. These ductile alloys cannot be converted to powder form by the processes routinely used for oxides or intermetallics. Three methods of powder production from uranium alloys have been investigated within the US-RERTR program. These processes are grinding, cryogenic milling, and hydride-dehydride. In addition, a gas atomization process was investigated using gold as a surrogate for uranium. (author)

  1. Testing Bonds Between Brittle And Ductile Films

    Science.gov (United States)

    Wheeler, Donald R.; Ohsaki, Hiroyuki

    1989-01-01

    Simple uniaxial strain test devised to measure intrinsic shear strength. Brittle film deposited on ductile stubstrate film, and combination stretched until brittle film cracks, then separates from substrate. Dimensions of cracked segments related in known way to tensile strength of brittle film and shear strength of bond between two films. Despite approximations and limitations of technique, tests show it yields semiquantitative measures of bond strengths, independent of mechanical properties of substrates, with results reproducible with plus or minus 6 percent.

  2. Strong, Ductile Rotor For Cryogenic Flowmeters

    Science.gov (United States)

    Royals, W. T.

    1993-01-01

    Improved magnetic flowmeter rotor resists cracking at cryogenic temperatures, yet provides adequate signal to magnetic pickup outside flowmeter housing. Consists mostly of stainless-steel alloy 347, which is ductile and strong at low temperatures. Small bead of stainless-steel alloy 410 welded in groove around circumference of round bar of stainless-steel alloy 347; then rotor machined from bar. Tips of rotor blades contain small amounts of magnetic alloy, and passage of tips detected.

  3. Deformation-induced martensitic transformation in a new metastable β titanium alloy

    International Nuclear Information System (INIS)

    Sadeghpour, S.; Abbasi, S.M.; Morakabati, M.

    2015-01-01

    A new metastable β titanium alloy, Ti-4Al-7Mo-3V-3Cr (wt.%), was designed using d-electron method, aiming to tailor the deformation mechanism. Microstructural and X-ray diffraction analysis of deformed specimens conforming with the theoretical prediction of d-electron method, confirmed the formation of stress-induced martensite (SIM) and mechanical twinning as the deformation mechanisms. The effect of initial grain size, strain level and strain rate on the formation of SIM were investigated. The results showed that in a given grain size, the volume fraction of SIM initially increases intensively and then follows with lower rate reaching a saturation at 35% reduction. It was observed that after a decrease in the martensite laths interspace down to less than 2 μm as a result of increasing the strain, some secondary martensite laths forms within the primary ones. It was found that with an increase in grain size from 150 μm to 250 μm, the volume fraction of SIM increases while a further increase in grain size up to 500 μm leads to a decrease in SIM volume fraction. The compression test results at different strain rates ranging from 0.7 × 10"−"4 to 0.7 × 10"−"1 s"−"1 showed SIM transformation occurs at all strain rates and although the triggering stress for SIM transformation increases continuously with an increase in strain rate, the volume fraction of SIM is independent of the strain rate. - Highlights: • A new metastable beta titanium was designed using d-electron method. • d-electron method was successful in predicting the deformation mechanisms. • The effects of grain size, strain level and strain rate on the SIM were studied.

  4. STUDY REGARDING EFFICIENCY OF INDUCED GENETIC TRANSFORMATION IN BACILLUS LICHENIFORMIS WITH PLASMID DNA

    Directory of Open Access Journals (Sweden)

    T. VINTILĂ

    2007-05-01

    Full Text Available A strain of Bacillus licheniformis was subject to genetic transformation with plasmid vectors (pLC1 and pNC61, using electroporation technique, protoplast transformation and bivalent cations (CaCl2 mediated transformation. In the case of transformation by electroporation of Bacillus licheniformis B40, the highest number of transformed colonies (3 were obtained only after a 1,79 KV electric shock, for 2,2 milliseconds. Using this transformation technique we have obtained six kanamycin resistant transformants. The frequency of Bacillus licheniformis B40 protoplasts transformation using pLC1 and pNC61 plasmid vectors is approximately 10% (TF = 10%. As a result of pLC1 plasmid integration in Bacillus licheniformis protoplasts, six kanamycin resistant transformants were obtained. The pNC61 plasmid, which confers trimethoprim resistance, does not integrate in receiver cells by protoplast transformation. The direct genetic transformation in the presence of bivalent cations (CaCl2, mediated by pLC1 and pNC61 plasmid vectors, produce a low transformation frequency. Using this technique, we have obtained three trimethoprim resistant colonies and four kanamycin resistant colonies. The chemical way of transformation is the only technique, which realizes the integration of pNC61 in B. licheniformis B40 cells.

  5. Direct evidence for stress-induced transformation between coexisting multiple martensites in a Ni–Mn–Ga multifunctional alloy

    International Nuclear Information System (INIS)

    Huang, L; Cong, D Y; Dong, Y H; Zhang, Y; Wang, Y D; Wang, Z L; Nie, Z H; Ren, Y

    2015-01-01

    The structural response of coexisting multiple martensites to stress field in a Ni–Mn–Ga multifunctional alloy was investigated by the in situ high-energy x-ray diffraction technique. Stress-induced transformation between coexisting multiple martensites was observed at 110 K, at which five-layered modulated (5M), seven-layered modulated (7M) and non-modulated (NM) martensites coexist. We found that a tiny stress of as low as 0.5 MPa could trigger the transformation from 5M and 7M martensites to NM martensite and this transformation is partly reversible. Besides the transformation between coexisting multiple martensites, rearrangement of martensite variants also occurs during loading, at least at high stress levels. The present study is instructive for designing advanced multifunctional alloys with easy actuation. (paper)

  6. Improvement in the assessment of direct and facilitated ion transfers by electrochemically induced redox transformations of common molecular probes

    DEFF Research Database (Denmark)

    Zhou, Min; Gan, Shiyu; Zhong, Lijie

    2012-01-01

    A new strategy based on a thick organic film modified electrode allowed us, for the first time, to explore the voltammetric processes for a series of hydrophilic ions by electrochemically induced redox transformations of common molecular probes. During the limited time available for voltammetry, ...

  7. Phase I study of transforming growth factor-beta 3 mouthwashes for prevention of chemotherapy-induced mucositis

    NARCIS (Netherlands)

    Wymenga, ANM; van der Graaf, WTA; Hofstra, LS; Spijkervet, FKL; Timens, W; Timmer-Bosscha, H; Sluiter, WJ; van Buuren, AHJAW; Mulder, NH; de Vries, EGE

    The purpose of this study was to establish the safety and tolerability of recombinant transforming growth factor-beta 3 (TGF-beta 3; CGP 46614) mouthwashes intended for prevention of chemotherapy-induced mucositis. Local effects were especially analyzed by objective and subjective measurements of

  8. Probing the Evolution of Retained Austenite in TRIP Steel During Strain-Induced Transformation: A Multitechnique Investigation

    Science.gov (United States)

    Haidemenopoulos, G. N.; Constantinou, M.; Kamoutsi, H.; Krizan, D.; Bellas, I.; Koutsokeras, L.; Constantinides, G.

    2018-06-01

    X-ray diffraction analysis, magnetic force microscopy, and the saturation magnetization method have been employed to study the evolution of the percentage and size of retained austenite (RA) particles during strain-induced transformation in a transformation-induced plasticity (TRIP) steel. A low-alloy TRIP-700 steel with nominal composition Fe-0.2C-0.34Si-1.99Mn-1Al (mass%) was subjected to interrupted tensile testing at strain levels of 0-22% and the microstructure subsequently studied. The results of the three experimental techniques were in very good agreement regarding the estimated austenite volume fraction and its evolution with strain. Furthermore, this multitechnique approach revealed that the average particle size of RA reduced as the applied strain was increased, suggesting that larger particles are less stable and more susceptible to strain-induced phase transformation. Such experimentally determined evolution of the austenite size with strain could serve as an input to kinetic models that aim to predict the strain-induced transformation in low-alloy TRIP steels.

  9. Occurrence and properties of antibodies against virus-associated transformation proteins in radiation-induced osteosarcomas in mice

    International Nuclear Information System (INIS)

    Hofherr, J.

    1983-01-01

    In this thesis it was looked if there is an immunresponse against such viral oncogene products in mice with radiation-induced osteosarcomas. Sera from mice with transplantable radiation-induced osteosacomas showed strong cytotoxicity against cells from a Moloney sarcoma virus-induced tumor and to a smaller extent also against FBJ osteosarcoma virus-transformed nonproducer cells. The cytotoxic activity was bound to the IgM fraction of the sera. Immunprecipitation of 35 S-methionine labelled virus- or radiation-transformed cells with cytotoxic sera showed on PAGE two proteins of molecular weights (m.w.) of about 50-55 kD. A protein of about 38 kD was expressed only in transformed cells whereas another protein of about 43 kD was seen in all cells except in uninfected muscle cells of adult mice. In order to further characterize the nature of these antigens immunprecipitates with unlabelled cells were tested in a protein kinase assay with gamma 32 P ATP and analysed on PAGE. Phosphorylation of proteins occured predominantly of more than 70 kD m.w., of about 68 kD, 50-55 kD and to a lesser extent also of about 32, 34 and 39 kD. The phosphorylation site of the proteins was at serine and threonine residues. These results indicate that mice with radiation-induced osteosarkomas develop antibodies against 'in vivo' and 'in vitro'-sarcoma virus transformed cells. (orig./MG) [de

  10. Numerical simulation of ductile-brittle behaviour of cracks in aluminium and bcc iron

    International Nuclear Information System (INIS)

    Zacharopoulos, Marios

    2017-01-01

    The principal aim of the present dissertation is to investigate the role of sharp cracks on the mechanical behaviour of crystals under load at the atomic scale. The question of interest is how a pure crystal, which contains a single crack in mechanical equilibrium, deforms. Two metals were considered: aluminium, ductile at any temperature below its melting point, and iron, being transformed from ductile to brittle upon decreasing temperature below T=77 K. Cohesive forces in both metals were modeled via phenomenological n-body potentials. A (010)[001] mode I nano-crack was introduced in the perfect crystalline lattice of each of the studied metals by using appropriate displacements ascribed by anisotropic elasticity. At T=0 K, equilibrium crack configurations were obtained via energy minimization with a mixed type of boundary conditions. Both models revealed that the crack configurations remained stable under a finite range of applied stresses due to the lattice trapping effect. The present thesis proposes a novel approach to interpret the intrinsic mechanical behaviour of the two metallic systems under loading. In particular, the ductile or brittle response of a crystalline system can be determined by examining whether the lattice trapping barrier of a pre-existing crack is sufficient to cause the glide of pre-existing static dislocations on the available slip systems. Simulation results along with experimental data demonstrate that, according to the model proposed, aluminium and iron are ductile and brittle at T=0 K, respectively. (author) [fr

  11. Irradiation effects on tensile ductility and dynamic toughness of ferritic-martensitic 7-12 Cr steels

    International Nuclear Information System (INIS)

    Preininger, D.

    2006-01-01

    The superimposed effect of irradiation-induced hardening by small defects (clusters, dislocation loops) and chromium-rich - precipitate formations on tensile ductility and Charpy-impact behaviour of various ferritic-martensitic (7-13)CrWVTa(Ti)-RAFM steels have been examined by micro-mechanical deformation and ductile/dynamic fracture models. Analytical relations have been deduced describing irradiation-induced changes of uniform ductility and fracture strain as well as ductile-to-brittle transition temperature DBTT and ductile upper shelf energy USE observed from impact tests. The models apply work-hardening with competitive action of relevant dislocation multiplication and annihilation reactions. The impact model takes into account stress intensity with local plasticity and fracture within the damage zone of main crack. Especially, the influences of radiation-induced changes in ductile and dynamic fracture stresses have been considered together with effects from strain rate sensitivity of strength, precipitate morphology as mean size dp and volume fraction fv as well as deformation temperature and strain rate. For these, particularly the correlation between tensile ductility and impact properties have been examined. Strengthening by clusters and loops generally reduces uniform ductility, and more stronger fracture strain as well as ductile upper shelf energy USE and additionally increases DBTT for constant fracture stresses. A superimposed precipitation hardening by formation of 3-6 nm, f v 6 nm, which clear above the sharable limit of coherent precipitates increases with increasing fraction fv and but strongly reduces with increasing matrix strength due to full martensitic structure, higher C, N alloying contents and pronounced hardening by irradiation-induced cluster and loop formations. A combined increase of fracture stresses due to irradiation-induced changes of the grain boundary structure diminishes the strength-induced increase in DBTT and more stronger

  12. Ductility Enhancement of Molybdenum Phase by Nano-sizedd Oxide Dispersions

    Energy Technology Data Exchange (ETDEWEB)

    Bruce Kang

    2008-07-31

    The present research is focused on ductility enhancement of molybdenum (Mo) alloys by adding nano-sized oxide particles to the alloy system. The research approach includes: (1) determination of microscopic mechanisms responsible for the macroscopic ductility enhancement effects through atomistic modeling of the metal-ceramic interface; (2) subsequent computer simulation-aided optimization of composition and nanoparticle size of the dispersion for improved performance; (3) synthesis and characterization of nanoparticle dispersion following the guidance from atomistic computational modeling analyses (e.g., by processing a small sample of Mo alloy for evaluation); and (4) experimental testing of the mechanical properties to determine optimal ductility enhancement.Through atomistic modeling and electronic structure analysis using full-potential linearized muffin-tin orbital (FP-LMTO) techniques, research to date has been performed on a number of selected chromium (Cr) systems containing nitrogen (N) and/or magnesium oxide (MgO) impurities. The emphasis has been on determining the properties of the valence electrons and the characteristics of the chemical bonds they formed. It was found that the brittle/ductile behavior of this transitional metal system is controlled by the relative population of valence charges: bonds formed by s valence electrons yield metallic, ductile behavior, whereas bonds formed by d valence electrons lead to covalent, brittle behavior. The presence of valence bands from impurities also affects the metal bonding, thereby explaining the detrimental and beneficial effects induced by the inclusion of N impurities and MgO dispersions. These understandings are useful for optimizing ductility enhancement effects on the dispersion materials.

  13. Determination of aluminium induced metabolic changes in mice liver: a Fourier transform infrared spectroscopy study.

    Science.gov (United States)

    Sivakumar, S; Sivasubramanian, J; Khatiwada, Chandra Prasad; Manivannan, J; Raja, B

    2013-06-01

    In this study, we made a new approach to evaluate aluminium induced metabolic changes in liver tissue of mice using Fourier transform infrared spectroscopy analysis taking one step further in correlation with strong biochemical evidence. This finding reveals the alterations on the major biochemical constituents, such as lipids, proteins, nucleic acids and glycogen of the liver tissues of mice. The peak area value of amide A significantly decrease from 288.278±3.121 to 189.872±2.012 between control and aluminium treated liver tissue respectively. Amide I and amide II peak area value also decrease from 40.749±2.052 to 21.170±1.311 and 13.167±1.441 to 8.953±0.548 in aluminium treated liver tissue respectively. This result suggests an alteration in the protein profile. The absence of olefinicCH stretching band and CO stretching of triglycerides in aluminium treated liver suggests an altered lipid levels due to aluminium exposure. Significant shift in the peak position of glycogen may be the interruption of aluminium in the calcium metabolism and the reduced level of calcium. The overall findings exhibit that the liver metabolic program is altered through increasing the structural modification in proteins, triglycerides and quantitative alteration in proteins, lipids, and glycogen. All the above mentioned modifications were protected in desferrioxamine treated mice. Histopathological results also revealed impairment of aluminium induced alterations in liver tissue. The results of the FTIR study were found to be in agreement with biochemical studies and which demonstrate FTIR can be used successfully to indicate the molecular level changes. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Role of Pin1 in UVA-induced cell proliferation and malignant transformation in epidermal cells

    International Nuclear Information System (INIS)

    Han, Chang Yeob; Hien, Tran Thi; Lim, Sung Chul; Kang, Keon Wook

    2011-01-01

    Highlights: → Pin1 expression is enhanced by low energy UVA irradiation in both skin tissues of hairless mice and JB6 C141 epidermal cells. → UVA irradiation increases activator protein-1 activity and cyclin D1 in a Pin1-dependent manner. → UVA potentiates EGF-inducible, anchorage-independent growth of epidermal cells, and this is suppressed by Pin1 inhibition or by anti-oxidant. -- Abstract: Ultraviolet A (UVA) radiation (λ = 320-400 nm) is considered a major cause of human skin cancer. Pin1, a peptidyl prolyl isomerase, is overexpressed in most types of cancer tissues and plays an important role in cell proliferation and transformation. Here, we demonstrated that Pin1 expression was enhanced by low energy UVA (300-900 mJ/cm 2 ) irradiation in both skin tissues of hairless mice and JB6 C141 epidermal cells. Exposure of epidermal cells to UVA radiation increased cell proliferation and cyclin D1 expression, and these changes were blocked by Pin1 inhibition. UVA irradiation also increased activator protein-1 (AP-1) minimal reporter activity and nuclear levels of c-Jun, but not c-Fos, in a Pin1-dependent manner. The increases in Pin1 expression and in AP-1 reporter activity in response to UVA were abolished by N-acetylcysteine (NAC) treatment. Finally, we found that pre-exposure of JB6 C141 cells to UVA potentiated EGF-inducible, anchorage-independent growth, and this effect was significantly suppressed by Pin1inhibition or by NAC.

  15. Impaired CK1 delta activity attenuates SV40-induced cellular transformation in vitro and mouse mammary carcinogenesis in vivo.

    Directory of Open Access Journals (Sweden)

    Heidrun Hirner

    Full Text Available Simian virus 40 (SV40 is a powerful tool to study cellular transformation in vitro, as well as tumor development and progression in vivo. Various cellular kinases, among them members of the CK1 family, play an important role in modulating the transforming activity of SV40, including the transforming activity of T-Ag, the major transforming protein of SV40, itself. Here we characterized the effects of mutant CK1δ variants with impaired kinase activity on SV40-induced cell transformation in vitro, and on SV40-induced mammary carcinogenesis in vivo in a transgenic/bi-transgenic mouse model. CK1δ mutants exhibited a reduced kinase activity compared to wtCK1δ in in vitro kinase assays. Molecular modeling studies suggested that mutation N172D, located within the substrate binding region, is mainly responsible for impaired mutCK1δ activity. When stably over-expressed in maximal transformed SV-52 cells, CK1δ mutants induced reversion to a minimal transformed phenotype by dominant-negative interference with endogenous wtCK1δ. To characterize the effects of CK1δ on SV40-induced mammary carcinogenesis, we generated transgenic mice expressing mutant CK1δ under the control of the whey acidic protein (WAP gene promoter, and crossed them with SV40 transgenic WAP-T-antigen (WAP-T mice. Both WAP-T mice as well as WAP-mutCK1δ/WAP-T bi-transgenic mice developed breast cancer. However, tumor incidence was lower and life span was significantly longer in WAP-mutCK1δ/WAP-T bi-transgenic animals. The reduced CK1δ activity did not affect early lesion formation during tumorigenesis, suggesting that impaired CK1δ activity reduces the probability for outgrowth of in situ carcinomas to invasive carcinomas. The different tumorigenic potential of SV40 in WAP-T and WAP-mutCK1δ/WAP-T tumors was also reflected by a significantly different expression of various genes known to be involved in tumor progression, specifically of those involved in wnt-signaling and DNA

  16. Uptake of extracellular DNA: Competence induced pili in natural transformation of Streptococcus pneumoniae

    Science.gov (United States)

    Muschiol, Sandra; Balaban, Murat; Normark, Staffan; Henriques-Normark, Birgitta

    2015-01-01

    Transport of DNA across bacterial membranes involves complex DNA uptake systems. In Gram-positive bacteria, the DNA uptake machinery shares fundamental similarities with type IV pili and type II secretion systems. Although dedicated pilus structures, such as type IV pili in Gram-negative bacteria, are necessary for efficient DNA uptake, the role of similar structures in Gram-positive bacteria is just beginning to emerge. Recently two essentially very different pilus structures composed of the same major pilin protein ComGC were proposed to be involved in transformation of the Gram-positive bacterium Streptococcus pneumoniae – one is a long, thin, type IV pilus-like fiber with DNA binding capacity and the other one is a pilus structure that was thicker, much shorter and not able to bind DNA. Here we discuss how competence induced pili, either by pilus retraction or by a transient pilus-related opening in the cell wall, may mediate DNA uptake in S. pneumoniae. PMID:25640084

  17. Serum-induced G0/G1 transition in chemically transformed 3T3 cells

    International Nuclear Information System (INIS)

    Gray, H.E.; Buchou, T.; Mester, J.

    1987-01-01

    Quiescent, chemically transformed (benzo-a-pyrene) BALB/c 3T3 cells (BP A31) enter the cell division cycle when exposed to complete medium containing 10% fetal calf serum (FCS); the number of cells recruited is a function of the duration of serum exposure. The recruitment of cells by short (<4 h) serum pulses is not inhibited by simultaneous exposure to cycloheximide (CH), and therefore the initial commitment does not require protein synthesis. The cells enter S phase with a constant delay following the removal of CH, even if CH exposure has been continued for as long as 20 h after the end of the serum pulse. The cell recruitment by serum pulses was inhibited by 5,6-dichloro-1-β-D-ribofuranosyl-benzimidazole (DRB), an inhibitor of cytoplasmic mRNA accumulation. These data suggest that serum exposure produces a stable memory that is necessary and sufficient for the eventual progression through G1 to S phase that occurs when protein synthesis is resumed after the removal of CH; this memory probably consists of mRNA species that are induced by serum and that are stable in the absence of protein synthesis. Unexpectedly, pretreatment of quiescent BP A31 cells with CH (8-24 h) dramatically increased the fraction of the total cell population that is recruited by a serum pulse of fixed duration

  18. Strain-Induced Martensitic Transformation and Texture Evolution in Cold-Rolled Co–Cr Alloys

    Directory of Open Access Journals (Sweden)

    Yusuke Onuki

    2018-05-01

    Full Text Available Co–Cr alloys have been used in biomedical purposes such as stents and artificial hip joints. However, the difficulty of plastic deformation limits the application of the alloys. During the deformation, Co–Cr alloys often exhibit strain-induced martensitic transformation (SIMT, which is a possible reason for the low formability. The distinct increase in dislocation density in the matrix phase may also result in early fractures. Since these microstructural evolutions accompany the textural evolution, it is crucial to understand the relationship among the SIMT, the increase in dislocations, and the texture evolution. To characterize those at the same time, we conducted time-of-flight neutron diffraction experiments at iMATERIA beamline at the Japan Proton Accelerator Research Complex (J-PARC Materials and Life Science Experimental Facility (MLF, Ibaraki, Japan. The cold-rolled sheets of Co–29Cr–6Mo (CCM and Co–20Cr–15W–10Ni (CCWN alloys were investigated in this study. As expected from the different stacking fault energies, the SIMT progressed more rapidly in the CCM alloy. The dislocation densities of the matrix phases of the CCM and CCWN alloys increased similarly with an increase in the rolling reduction. These results suggest that the difference in deformability between the CCM and CCWN alloys originate not from the strain hardening of the matrix phase but from the growth behaviors of the martensitic phase.

  19. Transformation of methano[60]fullerenes in dihydrofullerofuranes induced by electron transfer

    International Nuclear Information System (INIS)

    Yanilkin, V.V.; Toropchina, A.V.; Morozov, V.I.; Nastapova, N.V.; Gubskaya, V.P.; Sibgatullina, F.G.; Azancheev, N.M.; Efremov, Yu.Ya.; Nuretdinov, I.A.

    2004-01-01

    The electrochemical reduction of methano[60]fullerenes (61-acetyl-61-(diethoxyphosphoryl)methano-60-fullerene 1, 61-acetyl-61-(diisopropoxyphosphoryl)methano-60-fullerene 2, 61-(2,2-diethoxyacetyl)-61-(diethoxy-phosphoryl)methano-60-fullerene 3, 61-phenyl-61-(1,2-dioxo-3,3-dimethyl-buthyl)methano-60-fullerene 4) in o-dichlorobenzene-DMF (3:1 v/v)/0.1 M Bu 4 NBF 4 on a glass-carbon electrode proceeds in a few steps. The reversible transfer of the first electron results in the formation of radical anions registered by ESR method. The subsequent reduction proceeds differently because of the various stability of anionic intermediates. The radical anions of the methanofullerenes 3 and 4 are less stable than the radical anions of compounds 1 and 2 and less stable than the radical anions of methanofullerenes, which contain an ester and/or a phosphonate group. The opening of a cyclopropane ring occurs during the stage of the formation of radical trianions of methanofullerenes 1, 2. The same process for compounds 3, 4 proceeds slowly in radical anions and fast in dianions. The opening of cyclopropane ring for all compounds is not accompanied by the elimination of methanogroup and results in the formation of dihydrofullerenofurane derivatives. The transformation of methanofullerene 3 induced by single electron transfer proceeds via a chain reaction mechanism

  20. Nanoscale multiphase phase field approach for stress- and temperature-induced martensitic phase transformations with interfacial stresses at finite strains

    Science.gov (United States)

    Basak, Anup; Levitas, Valery I.

    2018-04-01

    A thermodynamically consistent, novel multiphase phase field approach for stress- and temperature-induced martensitic phase transformations at finite strains and with interfacial stresses has been developed. The model considers a single order parameter to describe the austenite↔martensitic transformations, and another N order parameters describing N variants and constrained to a plane in an N-dimensional order parameter space. In the free energy model coexistence of three or more phases at a single material point (multiphase junction), and deviation of each variant-variant transformation path from a straight line have been penalized. Some shortcomings of the existing models are resolved. Three different kinematic models (KMs) for the transformation deformation gradient tensors are assumed: (i) In KM-I the transformation deformation gradient tensor is a linear function of the Bain tensors for the variants. (ii) In KM-II the natural logarithms of the transformation deformation gradient is taken as a linear combination of the natural logarithm of the Bain tensors multiplied with the interpolation functions. (iii) In KM-III it is derived using the twinning equation from the crystallographic theory. The instability criteria for all the phase transformations have been derived for all the kinematic models, and their comparative study is presented. A large strain finite element procedure has been developed and used for studying the evolution of some complex microstructures in nanoscale samples under various loading conditions. Also, the stresses within variant-variant boundaries, the sample size effect, effect of penalizing the triple junctions, and twinned microstructures have been studied. The present approach can be extended for studying grain growth, solidifications, para↔ferro electric transformations, and diffusive phase transformations.

  1. Fe(II)-induced transformation from ferrihydrite to lepidocrocite and goethite

    International Nuclear Information System (INIS)

    Liu Hui; Li Ping; Zhu Meiying; Wei Yu; Sun Yuhan

    2007-01-01

    The transformation of Fe(II)-adsorbed ferrihydrite was studied. Data tracking the formation of products as a function of pH, temperature and time is presented. The results indicate that trace of Fe(II) adsorbed on ferrihydrite can accelerate its transformation obviously. The products are lepidocrocite and/or goethite and/or hematite, which is different from those without Fe(II). That is, Fe(II) not only accelerates the transformation of ferrihydrite but also leads to the formation of lepidocrocite by a new path. The behavior of Fe(II) is shown in two aspects-catalytic dissolution-reprecipitation and catalytic solid-state transformation. The results indicate that a high temperature and a high pH(in the range from 5 to 9) are favorable to solid-state transformation and the formation of hematite, while a low temperature and a low pH are favorable to dissolution-reprecipitation mechanism and the formation of lepidocrocite. Special attentions were given to the formation mechanism of lepidocrocite and goethite. - Graphical abstract: Fe(II)-adsorbed ferrihydrite can rapidly transform into lepidocrocite or/and goethite or/and hematite. Which product dominates depends on the transformation conditions of ferrihydrite such as temperature, pH, reaction time, etc. In the current system, there exist two transformation mechanisms. One is dissolution/reprecipitation and the other is solid-state transformation. The transformation mechanisms from Fe(II)-adsorbed ferrihydrite to lepidocrocite and goethite were investigated

  2. Human cell transformation in the study of sunlight-induced cancers in the skin of man

    International Nuclear Information System (INIS)

    Sutherland, B.M.; Bennett, P.V.

    1988-01-01

    Human cell transformation provides a powerful approach to understanding - at the cellular and molecular levels - induction of cancers in the skin of man. A principal approach to this problem is the direct transformation of human skin cells by exposure to ultraviolet and/or near-UV radiation. The frequency of human cells transformed to anchorage independence increases with radiation exposure; the relative transforming efficiencies of different wavelengths implies that direct absorption by nucleic acids is a primary initial event. Partial reversal of potential transforming lesions by photoreactivation suggests that pyrimidine dimers, as well as other lesions, are important in UV transformation of human cells. Human cells can also be transformed by transfection with cloned oncogenes, or with DNAs from tumors or tumor cell lines. Cells treated by the transfection procedure (but without DNA) or cells transfected with DNAs from normal mammalian cells or tissues show only background levels of transformation. Human cells can be transformed to anchorage-independent growth by DNAs ineffective in transformation of NIH 3T3 cells (including most human skin cancers), permitting the analysis of oncogenic molecular changes even in tumor DNAs difficult or impossible to analyze in rodent cell systems. 29 refs.; 4 figs.; 1 table

  3. Characterization of Austempered Ferritic Ductile Iron

    Science.gov (United States)

    Dakre, Vinayak S.; Peshwe, D. R.; Pathak, S. U.; Likhite, A. A.

    2018-04-01

    The ductile iron (DI) has graphite nodules enclose in ferrite envelop in pearlitic matrix. The pearlitic matrix in DI was converted to ferritic matrix through heat treatment. This heat treatment includes austenitization of DI at 900°C for 1h, followed by furnace cooling to 750°C & hold for 1h, then again furnace cooling to 690°C hold for 2h, then samples were allowed to cool in furnace. The new heat treated DI has graphite nodules in ferritic matrix and called as ferritic ductile iron (FDI). Both DIs were austenitized at 900°C for 1h and then quenched into salt bath at 325°C. The samples were soaked in salt bath for 60, 120, 180, 240 and 300 min followed by air cooling. The austempered samples were characterized with help of optical microscopy, SEM and X-ray diffraction analysis. Austempering of ferritic ductile iron resulted in finer ausferrite matrix as compared to ADI. Area fraction of graphite, ferrite and austenite were determining using AXIOVISION-SE64 software. Area fraction of graphite was more in FDI than that of as cast DI. The area fraction of graphite remains unaffected due to austempering heat treatment. Ausferritic matrix coarsened (feathered) with increasing in austempering time for both DI and FDI. Bulk hardness test was carried on Rockwell Hardness Tester with load of 150 kgf and diamond indenter. Hardness obtained in as cast DI is 28 HRC which decreased to 6 HRC in FDI due conversion of pearlitic matrix to ferritic matrix. Hardness is improved by austempering process.

  4. Temperature induced reversible polymorphic phase transformations in a bis-hydrazone compound

    Science.gov (United States)

    Jayant, Vikrant; Das, Dinabandhu

    2018-03-01

    Two reversible polymorphic phase transformation of 2,3-butanedione, 2,3- bis[4,4‧-bis(diethylamino)benzophenone hydrazone] (DEBH) have been identified in DSC experiment. Topotactic phase transformation of three polymorphs has been observed in variable temperature Single Crystal X-ray Diffraction experiment. The reversible phase transformation of bulk material has been confirmed by Powder X-ray diffraction study.

  5. From brittle to ductile fracture in disordered materials.

    Science.gov (United States)

    Picallo, Clara B; López, Juan M; Zapperi, Stefano; Alava, Mikko J

    2010-10-08

    We introduce a lattice model able to describe damage and yielding in heterogeneous materials ranging from brittle to ductile ones. Ductile fracture surfaces, obtained when the system breaks once the strain is completely localized, are shown to correspond to minimum energy surfaces. The similarity of the resulting fracture paths to the limits of brittle fracture or minimum energy surfaces is quantified. The model exhibits a smooth transition from brittleness to ductility. The dynamics of yielding exhibits avalanches with a power-law distribution.

  6. Hot Ductility Behavior of a Peritectic Steel during Continuous Casting

    OpenAIRE

    Arıkan, Mustafa

    2015-01-01

    Hot ductility properties of a peritectic steel for welded gas cylinders during continuous casting were studied by performing hot tensile tests at certain temperatures ranging from 1200 to 700 °C for some cooling rates by using Gleeble-3500 thermo-mechanical test and simulation machine in this study. The effects of cooling rate and strain rate on hot ductility were investigated and continuous casting process map (time-temperature-ductility) were plotted for this material. Reduction of area ...

  7. Ductile Damage Evolution and Strain Path Dependency

    International Nuclear Information System (INIS)

    Tasan, C. C.; Hoefnagels, J. M. P.; Peerlings, R. H. J.; Geers, M. G. D.; ten Horn, C. H. L. J.; Vegter, H.

    2007-01-01

    Forming limit diagrams are commonly used in sheet metal industry to define the safe forming regions. These diagrams are built to define the necking strains of sheet metals. However, with the rise in the popularity of advance high strength steels, ductile fracture through damage evolution has also emerged as an important parameter in the determination of limit strains. In this work, damage evolution in two different steels used in the automotive industry is examined to observe the relationship between damage evolution and the strain path that is followed during the forming operation

  8. Ductile alloys for sealing modular component interfaces

    Science.gov (United States)

    Marra, John J.; Wessell, Brian J.; James, Allister W.; Marsh, Jan H.; Gear, Paul J.

    2017-08-08

    A vane assembly (10) having: an airfoil (12) and a shroud (14) held together without metallurgical bonding there between; a channel (22) disposed circumferentially about the airfoil (12), between the airfoil (12) and the shroud (14); and a seal (20) disposed in the channel (22), wherein during operation of a turbine engine having the vane assembly (10) the seal (20) has a sufficient ductility such that a force generated on the seal (20) resulting from relative movement of the airfoil (12) and the shroud (14) is sufficient to plastically deform the seal (20).

  9. Thermoelastic martensite and shape memory effect in ductile Cu-Al-Mn alloys

    Science.gov (United States)

    Kainuma, R.; Takahashi, S.; Ishida, K.

    1996-08-01

    Ductile shape memory (SM) alloys of the Cu-AI-Mn system have been developed by controlling the degree of order in the β phase. Additions of Mn to the binary Cu-Al alloy stabilize the β phase and widen the single-phase region to lower temperature and lower Al contents. It is shown that Cu-Al-Mn alloys with low Al contents have either the disordered A2 structure or the ordered L21 structure with a lower degree of order and that they exhibit excellent ductility. The disordered A2 phase martensitically transforms to the disordered Al phase with a high density of twins. The martensite phase formed from the ordered L21 phase has the 18R structure. The SM effect accompanies both the A2 → Al and L21 → 18R martensitic transformations. These alloys exhibit 15 pct strain to failure, 60 to 90 pct rolling reduction without cracking, and 80 to 90 pct recovery from bend test in the martensitic condition. Experimental results on the microstructure, crystal structure, mechanical properties, and shape memory behavior in the ductile Cu-AI-Mn alloys are presented and discussed.

  10. Effect of Melting Techniques on Ductile Iron castings Properties

    Directory of Open Access Journals (Sweden)

    Bockus, S.

    2006-01-01

    Full Text Available The study was designed to investigate the effects of the charge, melting conditions, nodularizing and inoculation on the ductile iron castings properties. Results showed that the temperature and holding time of the melt in an induction furnace and the intensity of spheroidizing effect on the carbon and residual magnesium contents in the ductile iron castings. The same grade of ductile iron may be obtained using different chemical compositions. The castings of ductile iron will be ferritic as-cast only when large amount of pig iron in the charge and in addition some-steps inoculating treatment are used.

  11. Swift heavy ion induced phase transformation and thermoluminescence properties of zirconium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Lokesha, H.S. [Physics R & D Centre, PES Institute of Technology, BSK 3rd Stage, Bangalore 560085 (India); Nagabhushana, K.R., E-mail: bhushankr@gmail.com [Physics R & D Centre, PES Institute of Technology, BSK 3rd Stage, Bangalore 560085 (India); Department of Physics, PES University, BSK 3rd Stage, Bangalore 560085 (India); Singh, Fouran [Inter University Accelerator Center, Aruna Asaf Ali Marg, New Delhi 110 067 (India)

    2016-07-15

    Zirconium oxide (ZrO{sub 2}) powder is synthesized by combustion technique. XRD pattern of ZrO{sub 2} shows monoclinic phase with average crystallite size 35 nm. Pellets of ZrO{sub 2} are irradiated with 100 MeV swift Si{sup 7+}, Ni{sup 7+} and 120 MeV swift Ag{sup 9+} ions in the fluence range 3 × 10{sup 10}–3 × 10{sup 13} ions cm{sup −2}. XRD pattern show the main diffraction peak correspond to monoclinic and tetragonal phase of ZrO{sub 2} in 2θ range 27–33°. Structural phase transformation is observed for Ni{sup 7+} and Ag{sup 9+} ion irradiated samples at a fluence 1 × 10{sup 13} ions cm{sup −2} and 3 × 10{sup 12} ions cm{sup −2} respectively, since the deposited electronic energy loss exceeds an effective threshold (>12 keV nm{sup −1}). Phase transition induced by Ag{sup 9+} ion is nearly 2.9 times faster than Ni{sup 7+} ion at 1 × 10{sup 13} ions cm{sup −2}. Ag{sup 9+} ion irradiation leads two ion impact processes. Thermoluminescence (TL) glow curves exhibit two glows, a well resolved peak at ∼424 K and unresolved peak at 550 K for all SHI irradiated samples. TL response is decreased with increase of ion fluence. Beyond 3 × 10{sup 12} ions cm{sup −2}, samples don’t exhibit TL due to annihilation of defects.

  12. Low-Temperature Electron Beam-Induced Transformations of Cesium Lead Halide Perovskite Nanocrystals

    Science.gov (United States)

    2017-01-01

    Cesium lead halide perovskite (CsPbX3, with X = Br, Cl, I) nanocrystals have been found to undergo severe modifications under the high-energy electron beam irradiation of a transmission electron microscope (80/200 keV). In particular, in our previous work, together with halogen desorption, Pb2+ ions were found to be reduced to Pb0 and then diffused to form lead nanoparticles at temperatures above −40 °C. Here, we present a detailed irradiation study of CsPbBr3 nanocrystals at temperatures below −40 °C, a range in which the diffusion of Pb0 atoms/clusters is drastically suppressed. Under these conditions, the irradiation instead induces the nucleation of randomly oriented CsBr, CsPb, and PbBr2 crystalline domains. In addition to the Br desorption, which accompanies Pb2+ reduction at all the temperatures, Br is also desorbed from the CsBr and PbBr2 domains at low temperatures, leading to a more pronounced Br loss, thus the final products are mainly composed of Cs and Pb. The overall transformation involves the creation of voids, which coalesce upon further exposure, as demonstrated in both nanosheets and nanocuboids. Our results show that although low temperatures hinder the formation of Pb nanoparticles in CsPbBr3 nanocrystals when irradiated, the nanocrystals are nevertheless unstable. Consequently, we suggest that an optimum combination of temperature range, electron energy, and dose rate needs to be carefully chosen for the characterization of halide perovskite nanocrystals to minimize both the Pb nanoparticle formation and the structural decomposition. PMID:28983524

  13. Effect of Annealing in Magnetic Field on Ferromagnetic Nanoparticle Formation in Cu-Al-Mn Alloy with Induced Martensite Transformation.

    Science.gov (United States)

    Titenko, Anatoliy; Demchenko, Lesya

    2016-12-01

    The paper considers the influence of aging of high-temperature phase on subsequent martensitic transformation in Cu-Al-Mn alloy. The morphology of behavior of martensitic transformation as a result of alloy aging under annealing in a constant magnetic field with different sample orientation relatively to the field direction and without field was studied for direct control of the processes of martensite induction at cooling. Temperature dependences of electrical resistance, magnetic susceptibility, and magnetization, as well as field dependences of magnetization, and phase composition were found. The tendency to the oriented growth of precipitated ferromagnetic phase nanoparticles in a direction of applied field and to an increase of their volume fraction under thermal magnetic treatment of material that favors a reversibility of induced martensitic transformation is observed.

  14. Effect of mechanical properties on erosion resistance of ductile materials

    Science.gov (United States)

    Levin, Boris Feliksovih

    Solid particle erosion (SPE) resistance of ductile Fe, Ni, and Co-based alloys as well as commercially pure Ni and Cu was studied. A model for SPE behavior of ductile materials is presented. The model incorporates the mechanical properties of the materials at the deformation conditions associated with SPE process, as well as the evolution of these properties during the erosion induced deformation. An erosion parameter was formulated based on consideration of the energy loss during erosion, and incorporates the material's hardness and toughness at high strain rates. The erosion model predicts that materials combining high hardness and toughness can exhibit good erosion resistance. To measure mechanical properties of materials, high strain rate compression tests using Hopkinson bar technique were conducted at strain rates similar to those during erosion. From these tests, failure strength and strain during erosion were estimated and used to calculate toughness of the materials. The proposed erosion parameter shows good correlation with experimentally measured erosion rates for all tested materials. To analyze subsurface deformation during erosion, microhardness and nanoindentation tests were performed on the cross-sections of the eroded materials and the size of the plastically deformed zone and the increase in materials hardness due to erosion were determined. A nanoindentation method was developed to estimate the restitution coefficient within plastically deformed regions of the eroded samples which provides a measure of the rebounding ability of a material during particle impact. An increase in hardness near the eroded surface led to an increase in restitution coefficient. Also, the stress rates imposed below the eroded surface were comparable to those measured during high strain-rate compression tests (10sp3-10sp4 ssp{-1}). A new parameter, "area under the microhardness curve" was developed that represents the ability of a material to absorb impact energy. By

  15. Enhanced ductility of surface nano-crystallized materials by modulating grain size gradient

    International Nuclear Information System (INIS)

    Li, Jianjun; Soh, A K

    2012-01-01

    Surface nano-crystallized (SNC) materials with a graded grain size distribution on their surfaces have been attracting increasing scientific interest over the past few decades due to their good synergy of high strength and high ductility. However, to date most of the existing studies have focused on the individual contribution of three different aspects, i.e. grain size gradient (GSG), work-hardened region and surface compressive residual stresses, which were induced by surface severe plastic deformation processes, to the improved strength of SNC materials as compared with that of their coarse grained (CG) counterparts. And the ductility of these materials has hardly been studied. In this study, a combination of theoretical analysis and finite element simulations was used to investigate the role of GSG in tuning the ductility of SNC materials. It was found that the ductility of an SNC material can be comparable to that of its CG counterpart, while it simultaneously possessed a much higher strength than its CG core if the optimal GSG thickness and grain size of the topmost phase were adopted. A design map that can be used as a guideline for fabrication of SNC materials was also plotted. Our predictions were also compared with the corresponding experimental results. (paper)

  16. An investigation of ductile and brittle reinforcement on the fracture behavior of molybdenum disilicide composites

    International Nuclear Information System (INIS)

    Brooks, D.; Soboyejo, W.O.

    1994-01-01

    The results of an ongoing study of the effects of ductile and brittle reinforcement on the fracture toughness of particulate reinforced molybdenum disilicide matrix composites are presented. MoSi 2 composites reinforced with ductile Nb, Mo, and W particles are compared with MoSi 2 composites reinforced with SiC, TiB 2 , and partially stabilized zirconia (PSZ) particles. The effects of different degrees of yttria stabilization on zirconia reinforced composites will also be examined, as well as the effect of solid solution alloying with WSi 2 . The effects of multiple reinforcement of MoSi 2 with 20 vol.% Nb and 20 vol.% unstabilized zirconia (TZ-0) are discussed. The toughening is rationalized using micromechanical models for crack bridging, transformation toughening, and crack deflection

  17. Thermal Stability of Austempered Ductile Iron Evaluated in a Temperature Range of 20-300K

    Directory of Open Access Journals (Sweden)

    Dawid MYSZKA

    2016-05-01

    Full Text Available The aim of this article was to determine through changes in magnetic properties the stability of the austempered ductile iron (ADI microstructure during temperature changes in a range of 20 – 300 K. The measurements were taken in a vibrating sample magnetometer (VSM using Fe27Ni2TiMoAlNb austenitic stainless steel and four types of austempered ductile iron obtained under various heat treatment conditions. The plotted curves showing changes in the magnetisation degree as a function of temperature had a number of characteristic points illustrating changes taking place in the microstructure. For each of the materials examined, the martensite start temperature Ms and the temperature range within which the martensitic transformation takes place were identified.

  18. Dynamic behaviour and shock-induced martensite transformation in near-beta Ti-5553 alloy under high strain rate loading

    Directory of Open Access Journals (Sweden)

    Wang Lin

    2015-01-01

    Full Text Available Ti-5553 alloy is a near-beta titanium alloy with high strength and high fracture toughness. In this paper, the dynamic behaviour and shock-induced martensite phase transformation of Ti-5553 alloy with alpha/beta phases were investigated. Split Hopkinson Pressure Bar was employed to investigate the dynamic properties. Microstructure evolutions were characterized by Scanning Electronic Microscopy and Transmission Electron Microscope. The experimental results have demonstrated that Ti-5553 alloy with alpha/beta phases exhibits various strain rate hardening effects, both failure through adiabatic shear band. Ti-5553 alloy with Widmannstatten microstructure exhibit more obvious strain rate hardening effect, lower critical strain rate for ASB nucleation, compared with the alloy with Bimodal microstructures. Under dynamic compression, shock-induced beta to alpha” martensite transformation occurs.

  19. Dynamic behaviour and shock-induced martensite transformation in near-beta Ti-5553 alloy under high strain rate loading

    OpenAIRE

    Wang Lin; Wang Yangwei; Xu Xin; Liu Chengze

    2015-01-01

    Ti-5553 alloy is a near-beta titanium alloy with high strength and high fracture toughness. In this paper, the dynamic behaviour and shock-induced martensite phase transformation of Ti-5553 alloy with alpha/beta phases were investigated. Split Hopkinson Pressure Bar was employed to investigate the dynamic properties. Microstructure evolutions were characterized by Scanning Electronic Microscopy and Transmission Electron Microscope. The experimental results have demonstrated that Ti-5553 alloy...

  20. Symmetry-induced deformation and reconstructive phase transformation in metal-oxide interface: the Fe (001) example

    International Nuclear Information System (INIS)

    Lahoche, L.; Universite de Technologie de Compiegne; Lorman, V.; Roelandt, J.M.; Rochal, S.B.

    1996-01-01

    A model is proposed for the structural transformation and corresponding induced deformation in physical three-dimensional interface of the metal-oxide system. The thermodynamical and elastic state of the system is described by the Landau-Ginzbourg free energy. Calculated theoretical phase diagram shows several different types of isothermal growth processes. The model is applied to the case of the oxidation of the (001) Fe surface. (orig.)

  1. Ductile Damage and Fatigue Behavior of Semi-Finished Tailored Blanks for Sheet-Bulk Metal Forming Processes

    Science.gov (United States)

    Besserer, Hans-Bernward; Hildenbrand, Philipp; Gerstein, Gregory; Rodman, Dmytro; Nürnberger, Florian; Merklein, Marion; Maier, Hans Jürgen

    2016-03-01

    To produce parts from sheet metal with thickened functional elements, bulk forming operations can be employed. For this new process class, the term sheet-bulk metal forming has been established recently. Since sheet-bulk metal forming processes such as orbital forming generates triaxial stress and strain states, ductile damage is induced in the form of voids in the microstructure. Typical parts will experience cyclic loads during service, and thus, the influence of ductile damage on the fatigue life of parts manufactured by orbital forming is of interest. Both the formation and growth of voids were characterized following this forming process and then compared to the as-received condition of the ferritic deep drawing steel DC04 chosen for this study. Subsequent to the forming operation, the specimens were fatigued and the evolution of ductile damage and the rearrangement of the dislocation networks occurring during cyclic loading were determined. It was shown, that despite an increased ductile damage due to the forming process, the induced strain hardening has a positive effect on the fatigue life of the material. However, by analyzing the fatigued specimens a development of the ductile damage by an increasing number of voids and a change in the void shape were detected.

  2. Adaptive self-assembly and induced-fit transformations of anion-binding metal-organic macrocycles

    Science.gov (United States)

    Zhang, Ting; Zhou, Li-Peng; Guo, Xiao-Qing; Cai, Li-Xuan; Sun, Qing-Fu

    2017-06-01

    Container-molecules are attractive to chemists due to their unique structural characteristics comparable to enzymes and receptors in nature. We report here a family of artificial self-assembled macrocyclic containers that feature induced-fit transformations in response to different anionic guests. Five metal-organic macrocycles with empirical formula of MnL2n (M=Metal L=Ligand n=3, 4, 5, 6, 7) are selectively obtained starting from one simple benzimidazole-based ligand and square-planar palladium(II) ions, either by direct anion-adaptive self-assembly or induced-fit transformations. Hydrogen-bonding interactions between the inner surface of the macrocycles and the anionic guests dictate the shape and size of the product. A comprehensive induced-fit transformation map across all the MnL2n species is drawn, with a representative reconstitution process from Pd7L14 to Pd3L6 traced in detail, revealing a gradual ring-shrinking mechanism. We envisage that these macrocyclic molecules with adjustable well-defined hydrogen-bonding pockets will find wide applications in molecular sensing or catalysis.

  3. Precipitate-induced R-phase in martensitic transformation of as-spun and annealed Ti51Ni49 ribbons

    International Nuclear Information System (INIS)

    Wu, Ling-Mei; Chang, Shih-Hang; Wu, Shyi-Kaan

    2010-01-01

    Differential scanning calorimetry (DSC) results indicate that a two-step B2 → R → B19' martensitic transformation and a one-step B19' → B2 transformation exhibit in as-spun and in 200-600 o C annealed Ti 51 Ni 49 ribbons. Guinier-Preston (GP) zones and Ti 2 Ni precipitates are formed in ribbons annealed at ≤300 o C and ≥400 o C, respectively, and a conspicuous increase of DSC transformation peak temperature occurs in between 300 o C and 400 o C. The sizes of GP zones and Ti 2 Ni precipitates increase with increased annealing temperature. Transmission electron microscope (TEM) observations show that GP zones can induce the R-phase and both of them are formed along B2 directions. DSC and TEM tests show that Ti 2 Ni precipitates can induce the R-phase more than GP zones and the induced R-phase plates are also found along B2 directions. Experimental results show that the growing direction of R-phase plates is strongly confined by that of GP zones and Ti 2 Ni precipitates. The length of R-phase plates can reach about 2 μm in 300 o C annealed ribbon.

  4. Enhancement of alpha particles-induced cell transformation by oxygen free radicals and tumor necrosis factor released from phagocytes

    International Nuclear Information System (INIS)

    Gong Yifen; Guo Renfeng; Zhu Maoxiang; Shou Jiang; Ge Guixiu; Yang Zhihua; Hieber, L.; Peters, K.; Schippel, C.

    1997-01-01

    To illustrate the role of several endogenous factors released from phagocytes under chronic inflammation in radiation-induced cancer. C 3 T 10 T 1/2 and SHE cells were used as targets, and 238 Pu alpha source was used in alpha irradiation. The enhancement of TF in alpha particles-induced cell transformation by PMA-stimulated human blood and zymosan-stimulated U-937 cells was studied using formation of transformed foci. Transformation frequency (TF) of C 3 H 10 T 1/2 cells exposed to alpha particles of 0.5 Gy increased 2.1 and 2.8 fold by PMA-and PMA-stimulated neutrophils, respectively. TF of irradiated SHE cells at a dose of 0.5 Gy increased 12 fold by the addition of the supernatant of macrophage-like U-937 cell line. It was shown that TF of irradiated SHE cells at above dose increased 8 fold by the supernatant treated with anti-TNF-α could be subcultured continuously in vitro. The cells at 40 th passage and two lines of monoclone cells have the ability to develop malignant tumors in nude mice. The overdose of free radicals and TNF-α released from neutrophils and macrophages have played an important role in low dose radiation-induced cancer

  5. STUDY REGARDING EFFICIENCY OF INDUCED GENETIC TRANSFORMATION IN BACILLUS LICHENIFORMIS WITH PLASMID DNA

    Directory of Open Access Journals (Sweden)

    VINTILĂ T.

    2007-01-01

    Full Text Available A strain of Bacillus licheniformis was subject to genetic transformation with plasmidvectors (pLC1 and pNC61, using electroporation technique, protoplasttransformation and bivalent cations (CaCl2 mediated transformation. In the case oftransformation by electroporation of Bacillus licheniformis B40, the highest numberof transformed colonies (3 were obtained only after a 1,79 KV electric shock, for 2,2milliseconds. Using this transformation technique we have obtained six kanamycinresistant transformants. The frequency of Bacillus licheniformis B40 protoplaststransformation using pLC1 and pNC61 plasmid vectors is approximately 10% (TF =10%. As a result of pLC1 plasmid integration in Bacillus licheniformis protoplasts,six kanamycin resistant transformants were obtained. The pNC61 plasmid, whichconfers trimethoprim resistance, does not integrate in receiver cells by protoplasttransformation. The direct genetic transformation in the presence of bivalent cations(CaCl2, mediated by pLC1 and pNC61 plasmid vectors, produce a lowtransformation frequency. Using this technique, we have obtained three trimethoprimresistant colonies and four kanamycin resistant colonies. The chemical way oftransformation is the only technique, which realizes the integration of pNC61 in B.licheniformis B40 cells.

  6. Climate change induced transformations of agricultural systems: insights from a global model

    Science.gov (United States)

    Leclère, D.; Havlík, P.; Fuss, S.; Schmid, E.; Mosnier, A.; Walsh, B.; Valin, H.; Herrero, M.; Khabarov, N.; Obersteiner, M.

    2014-12-01

    Climate change might impact crop yields considerably and anticipated transformations of agricultural systems are needed in the coming decades to sustain affordable food provision. However, decision-making on transformational shifts in agricultural systems is plagued by uncertainties concerning the nature and geography of climate change, its impacts, and adequate responses. Locking agricultural systems into inadequate transformations costly to adjust is a significant risk and this acts as an incentive to delay action. It is crucial to gain insight into how much transformation is required from agricultural systems, how robust such strategies are, and how we can defuse the associated challenge for decision-making. While implementing a definition related to large changes in resource use into a global impact assessment modelling framework, we find transformational adaptations to be required of agricultural systems in most regions by 2050s in order to cope with climate change. However, these transformations widely differ across climate change scenarios: uncertainties in large-scale development of irrigation span in all continents from 2030s on, and affect two-thirds of regions by 2050s. Meanwhile, significant but uncertain reduction of major agricultural areas affects the Northern Hemisphere’s temperate latitudes, while increases to non-agricultural zones could be large but uncertain in one-third of regions. To help reducing the associated challenge for decision-making, we propose a methodology exploring which, when, where and why transformations could be required and uncertain, by means of scenario analysis.

  7. Climate change induced transformations of agricultural systems: insights from a global model

    International Nuclear Information System (INIS)

    Leclère, D; Havlík, P; Mosnier, A; Walsh, B; Valin, H; Khabarov, N; Obersteiner, M; Fuss, S; Schmid, E; Herrero, M

    2014-01-01

    Climate change might impact crop yields considerably and anticipated transformations of agricultural systems are needed in the coming decades to sustain affordable food provision. However, decision-making on transformational shifts in agricultural systems is plagued by uncertainties concerning the nature and geography of climate change, its impacts, and adequate responses. Locking agricultural systems into inadequate transformations costly to adjust is a significant risk and this acts as an incentive to delay action. It is crucial to gain insight into how much transformation is required from agricultural systems, how robust such strategies are, and how we can defuse the associated challenge for decision-making. While implementing a definition related to large changes in resource use into a global impact assessment modelling framework, we find transformational adaptations to be required of agricultural systems in most regions by 2050s in order to cope with climate change. However, these transformations widely differ across climate change scenarios: uncertainties in large-scale development of irrigation span in all continents from 2030s on, and affect two-thirds of regions by 2050s. Meanwhile, significant but uncertain reduction of major agricultural areas affects the Northern Hemisphere’s temperate latitudes, while increases to non-agricultural zones could be large but uncertain in one-third of regions. To help reducing the associated challenge for decision-making, we propose a methodology exploring which, when, where and why transformations could be required and uncertain, by means of scenario analysis. (letter)

  8. Constitutive modelling and identification of parameters of the plastic strain-induced martensitic transformation in 316L stainless steel at cryogenic temperatures

    CERN Document Server

    Garion, C; Sgobba, Stefano

    2006-01-01

    The present paper is focused on constitutive modelling and identification of parameters of the relevant model of plastic strain- induced martensitic transformation in austenitic stainless steels at low temperatures. The model used to describe the FCCrightward arrow BCC phase transformation in austenitic stainless steels is based on the assumption of linearization of the most intensive part of the transformation curve. The kinetics of phase transformation is described by three parameters: transformation threshold (p/sub xi/), slope (A) and saturation level (xi/sub L/). It is assumed that the phase transformation is driven by the accumulated plastic strain p. In addition, the intensity of plastic deformation is strongly coupled to the phase transformation via the description of mixed kinematic /isotropic linear plastic hardening based on the Mori-Tanaka homogenization. The theory of small strains is applied. Small strain fields, corresponding to phase transformation, are decomposed into the volumic and the shea...

  9. Suppression of alkylating agent induced cell transformation and gastric ulceration by low-dose alkylating agent pretreatment

    International Nuclear Information System (INIS)

    Onodera, Akira; Kawai, Yuichi; Kashimura, Asako; Ogita, Fumiya; Tsutsumi, Yasuo; Itoh, Norio

    2013-01-01

    Highlights: •Low-dose MNNG pretreatment suppresses high-dose MNNG induced in vitro transformation. •Gastric ulcers induced by high-dose MNNG decreased after low-dose MNNG pretreatment. •Efficacy of low-dose MNNG related to resistance of mutation and oxidative stress. -- Abstract: Exposure to mild stress by chemicals and radiation causes DNA damage and leads to acquired stress resistance. Although the linear no-threshold (LNT) model of safety assessment assumes risk from any dose, evidence from radiological research demonstrates a conflicting hormetic phenomenon known as the hormesis effect. However, the mechanisms underlying radiation hormesis have not yet been clarified, and little is known about the effects of low doses of chemical carcinogens. We analyzed the efficacy of pretreatment with low doses of the alkylating agent N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) on the subsequent induction of cell transformation and gastric ulceration by high-dose MNNG. We used an in vitro Balb/3T3 A31-1-1 cell transformation test and monitored the formation of gastric ulcers in 5-week-old male ICR mice that were administered MNNG in drinking water. The treatment concentrations of MNNG were determined by the cell survival rate and past reports. For low-dose in vitro and in vivo experiments, MNNG was used at 0.028 μM, and 2.8 μg/mL, respectively. The frequency of cell transformation induced by 10 μm MNNG was decreased by low-dose MNNG pretreatment to levels similar to that of spontaneous transformation. In addition, reactive oxygen species (ROS) and mutation frequencies induced by 10 μm MNNG were decreased by low-dose MNNG pretreatment. Importantly, low-dose MNNG pretreatment had no effect on cell proliferation. In vivo studies showed that the number of gastric ulcers induced by 1 mg/mL MNNG decreased after low-dose MNNG pretreatment. These data indicate that low-dose pretreatment with carcinogens may play a beneficial role in the prevention of chemical toxicity

  10. Suppression of alkylating agent induced cell transformation and gastric ulceration by low-dose alkylating agent pretreatment

    Energy Technology Data Exchange (ETDEWEB)

    Onodera, Akira, E-mail: onodera@pharm.kobegakuin.ac.jp [Department of Toxicology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Department of Pharmaceutical Sciences, Kobegakuin University, 1-1-3 Minatojima, Chuo-ku, Kobe 650-8586 (Japan); Kawai, Yuichi [Department of Pharmaceutical Sciences, Kobegakuin University, 1-1-3 Minatojima, Chuo-ku, Kobe 650-8586 (Japan); Kashimura, Asako; Ogita, Fumiya; Tsutsumi, Yasuo; Itoh, Norio [Department of Toxicology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871 (Japan)

    2013-06-14

    Highlights: •Low-dose MNNG pretreatment suppresses high-dose MNNG induced in vitro transformation. •Gastric ulcers induced by high-dose MNNG decreased after low-dose MNNG pretreatment. •Efficacy of low-dose MNNG related to resistance of mutation and oxidative stress. -- Abstract: Exposure to mild stress by chemicals and radiation causes DNA damage and leads to acquired stress resistance. Although the linear no-threshold (LNT) model of safety assessment assumes risk from any dose, evidence from radiological research demonstrates a conflicting hormetic phenomenon known as the hormesis effect. However, the mechanisms underlying radiation hormesis have not yet been clarified, and little is known about the effects of low doses of chemical carcinogens. We analyzed the efficacy of pretreatment with low doses of the alkylating agent N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) on the subsequent induction of cell transformation and gastric ulceration by high-dose MNNG. We used an in vitro Balb/3T3 A31-1-1 cell transformation test and monitored the formation of gastric ulcers in 5-week-old male ICR mice that were administered MNNG in drinking water. The treatment concentrations of MNNG were determined by the cell survival rate and past reports. For low-dose in vitro and in vivo experiments, MNNG was used at 0.028 μM, and 2.8 μg/mL, respectively. The frequency of cell transformation induced by 10 μm MNNG was decreased by low-dose MNNG pretreatment to levels similar to that of spontaneous transformation. In addition, reactive oxygen species (ROS) and mutation frequencies induced by 10 μm MNNG were decreased by low-dose MNNG pretreatment. Importantly, low-dose MNNG pretreatment had no effect on cell proliferation. In vivo studies showed that the number of gastric ulcers induced by 1 mg/mL MNNG decreased after low-dose MNNG pretreatment. These data indicate that low-dose pretreatment with carcinogens may play a beneficial role in the prevention of chemical toxicity

  11. Sunlight-induced Transformations of Graphene-based Nanomaterials in Aquatic Environments

    Science.gov (United States)

    Graphene-based nanomaterials and other related carbon nanomaterials (CNMs) can be released from products during their life cycles. Upon entry into aquatic environments, they are potentially transformed by photochemical reactions, oxidation reactions and biological processes, all ...

  12. Using Fourier transform infrared spectroscopy to evaluate biological effects induced by photodynamic therapy.

    Science.gov (United States)

    Lima, Cassio A; Goulart, Viviane P; Correa, Luciana; Zezell, Denise M

    2016-07-01

    Vibrational spectroscopic methods associated with multivariate statistical techniques have been succeeded in discriminating skin lesions from normal tissues. However, there is no study exploring the potential of these techniques to assess the alterations promoted by photodynamic effect in tissue. The present study aims to demonstrate the ability of Fourier Transform Infrared (FTIR) spectroscopy on Attenuated total reflection (ATR) sampling mode associated with principal component-linear discriminant analysis (PC-LDA) to evaluate the biochemical changes caused by photodynamic therapy (PDT) in skin neoplastic tissue. Cutaneous neoplastic lesions, precursors of squamous cell carcinoma (SCC), were chemically induced in Swiss mice and submitted to a single session of 5-aminolevulinic acid (ALA)-mediated PDT. Tissue sections with 5 μm thickness were obtained from formalin-fixed paraffin-embedded (FFPE) and processed prior to the histopathological analysis and spectroscopic measurements. Spectra were collected in mid-infrared region using a FTIR spectrometer on ATR sampling mode. Principal Component-Linear Discriminant Analysis (PC-LDA) was applied on preprocessed second derivatives spectra. Biochemical changes were assessed using PCA-loadings and accuracy of classification was obtained from PC-LDA . Sub-bands of Amide I (1,624 and 1,650 cm(-1) ) and Amide II (1,517 cm(-1) ) indicated a protein overexpression in non-treated and post-PDT neoplastic tissue compared with healthy skin, as well as a decrease in collagen fibers (1,204, 1,236, 1,282, and 1,338 cm(-1) ) and glycogen (1,028, 1,082, and 1,151 cm(-1) ) content. Photosensitized neoplastic tissue revealed shifted peak position and decreased β-sheet secondary structure of proteins (1,624 cm(-1) ) amount in comparison to non-treated neoplastic lesions. PC-LDA score plots discriminated non-treated neoplastic skin spectra from post-PDT cutaneous lesions with accuracy of 92.8%, whereas non-treated neoplastic

  13. Ring ductility of irradiated Inconel 706 and Nimonic PE16

    International Nuclear Information System (INIS)

    Huang, F.H.; Fish, R.L.

    1984-01-01

    The tensile ductility of fast neutron-irradiated, precipitation-hardened alloys Inconel 706 and Nimonic PE16 has been observed to be very low for certain test conditions. Explanations for the low ductility behavior have been sought by examination of broken tensile specimens with microscopy and other similar techniques. A ring compression test provides a method of evaluating the ductility of irradiated cladding specimens. Unlike the conventional uniaxial tensile testing in which the tensile specimen is deformed uniformly, the ring specimen is subjected to localized bending where the crack is initiated. The ductility can be estimated through an analysis of the bending of a ring in terms of strain hardening. Ring sections from irradiated, solution-treated Inconel 706 and Nimonic PE16 were compressed in the diametral direction to provide load-deflection records over a wide range of irradiation and test temperatures. Results showed that ductility in both alloys decreased with increasing test temperatures. The poorest ductility was exhibited at different irradiation temperatures in the two alloys - near 550 0 C for PE16 and 460 to 520 0 C for Inconel 706. The ring ductility data indicate that the grain boundary strength is a major factor in controlling the ductility of the PE16 alloy

  14. X-ray-induced in vitro neoplastic transformation of human diploid cells

    International Nuclear Information System (INIS)

    Borek, C.

    1980-01-01

    Techniques have recently been developed to identify and score quantitatively neoplastic transformation caused by x-rays in cultured cells derived from rodents. The present report describes for the first time the neoplastic transformation in vitro of human diploid cells by x-ray irradiation into cells which can progress in vitro into advanced stages of neoplastic development, namely, to form colonies in agar and give rise to tumors when injected into nude mice

  15. Langevin dynamics of conformational transformations induced by the charge-curvature interaction

    DEFF Research Database (Denmark)

    Gaididei, Yuri Borisovich; Gorria, C.; Christiansen, Peter Leth

    2009-01-01

    The role of thermal fluctuations in the conformational dynamics of a single closed filament is studied. It is shown that, due to the interaction between charges and bending degrees of freedom, initially circular chains may undergo transformation to polygonal shape.......The role of thermal fluctuations in the conformational dynamics of a single closed filament is studied. It is shown that, due to the interaction between charges and bending degrees of freedom, initially circular chains may undergo transformation to polygonal shape....

  16. 'Water Structure' versus 'Radical Scavenger' theories as explanations for the suppressive effects of DMSO and related compounds on radiation-induced transformation in vitro

    International Nuclear Information System (INIS)

    Kennedy, A.R.; Symons, M.C.R.

    1987-01-01

    We report here that dimethylsulfoxide (DMSO): (i) suppresses radiation-induced transformation in vitro, even when DMSO treatments begin as late as 10 days post-irradiation; (ii) inhibits the 12-O-tetradecanoylphorbol-13-acetate (TPA) enhancement of radiation-induced transformation in vitro; (iii) does not affect the expression of transformed cells as foci (when surrounded by non-transformed cells); and (iv) may be affecting radiation-induced transformation through its solvent properties (i.e. the 'Water Structure' theory), while its effects on the TPA enhancement of radiation transformation may be mediated by its free radical scavenging abilities. DMSO, dimethylformamide (DMF) and dimethylacetamide (DMA) are similar solvents which are all very effective in their ability to suppress radiation-induced transformation in vitro. As DMSO is known to be an extremely effective OH free-radical scavenging agent, while DMF and DMA are not as efficient at scavenging free radicals, our results suggest that properties other than free-radical scavenging ability may be important in the suppressive effects of these compounds on radiation-induced transformation in vitro. (author)

  17. Differential gene expression and clonal selection during cellular transformation induced by adhesion deprivation

    Directory of Open Access Journals (Sweden)

    Kumar Mahesh J

    2010-12-01

    Full Text Available Abstract Background Anchorage independent growth is an important hallmark of oncogenic transformation. Previous studies have shown that when adhesion dependent fibroblasts were prevented from adhering to a substrate they underwent anoikis. In the present study we have demonstrated how anoikis resistant cells gain the transformation related properties with sequential selection of genes. We have proposed this process as a model system for selection of transformed cells from normal cells. Results This report demonstrates that some fibroblasts can survive during late stages of anoikis, at which time they exhibit transformation-associated properties such as in vitro colony formation in soft agar and in vivo subcutaneous tumour formation in nude mice. Cytogenetic characterisation of these cells revealed that they contained a t (2; 2 derivative chromosome and they have a selective survival advantage in non adherent conditions. Gene expression profile indicated that these cells over expressed genes related to hypoxia, glycolysis and tumor suppression/metastasis which could be helpful in their retaining a transformed phenotype. Conclusion Our results reveal some new links between anoikis and cell transformation and they provide a reproducible model system which can potentially be useful to study multistage cancer and to identify new targets for drug development.

  18. Swift heavy ion irradiation induced phase transformation in undoped and niobium doped titanium dioxide composite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gautam, Subodh K., E-mail: subodhkgtm@gmail.com [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India); Chettah, Abdelhak [LGMM Laboratory, Université 20 Août 1955-Skikda, BP 26, 21000 Skikda (Algeria); Singh, R.G. [Department of Physics, Bhagini Nivedita College, Delhi University, Delhi 110043 (India); Ojha, Sunil; Singh, Fouran [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India)

    2016-07-15

    Study reports the effect of swift heavy ion (SHI) irradiation induced phase transformation in undoped and Niobium doped anatase TiO{sub 2} composite thin films. Investigations were carried out at different densities of electronic excitations (EEs) using 120 MeV Ag and 130 MeV Ni ions irradiations. Films were initially annealed at 900 °C and results revealed that undoped films were highly stable in anatase phase, while the Nb doped films showed the composite nature with the weak presence of Niobium penta-oxide (Nb{sub 2}O{sub 5}) phase. The effect at low density of EEs in undoped film show partial anatase to rutile phase transformation; however doped film shows only further growth of Nb{sub 2}O{sub 5} phase beside the anatase to rutile phase transformation. At higher density of EEs induced by Ag ions, registered continuous ion track of ∼3 nm in lattice which leads to nano-crystallization followed by decomposition/amorphization of rutile TiO{sub 2} and Nb{sub 2}O{sub 5} phases in undoped and doped films, respectively. However, Ni ions are only induced discontinuous sequence of ion tracks with creation of damage and disorder and do not show amorphization in the lattice. The in-elastic thermal spike calculations were carried out for anatase TiO{sub 2} phase to understand the effect of EEs on anatase to rutile phase transformation followed by amorphization in NTO films in terms of continuous and discontinuous track formation by SHI irradiation.

  19. Suberoylanilide hydroxamic acid (SAHA) inhibits EGF-induced cell transformation via reduction of cyclin D1 mRNA stability

    International Nuclear Information System (INIS)

    Zhang, Jingjie; Ouyang, Weiming; Li, Jingxia; Zhang, Dongyun; Yu, Yonghui; Wang, York; Li, Xuejun; Huang, Chuanshu

    2012-01-01

    Suberoylanilide hydroxamic acid (SAHA) inhibiting cancer cell growth has been associated with its downregulation of cyclin D1 protein expression at transcription level or translation level. Here, we have demonstrated that SAHA inhibited EGF-induced Cl41 cell transformation via the decrease of cyclin D1 mRNA stability and induction of G0/G1 growth arrest. We found that SAHA treatment resulted in the dramatic inhibition of EGF-induced cell transformation, cyclin D1 protein expression and induction of G0/G1 growth arrest. Further studies showed that SAHA downregulation of cyclin D1 was only observed with endogenous cyclin D1, but not with reconstitutionally expressed cyclin D1 in the same cells, excluding the possibility of SAHA regulating cyclin D1 at level of protein degradation. Moreover, SAHA inhibited EGF-induced cyclin d1 mRNA level, whereas it did not show any inhibitory effect on cyclin D1 promoter-driven luciferase reporter activity under the same experimental conditions, suggesting that SAHA may decrease cyclin D1 mRNA stability. This notion was supported by the results that treatment of cells with SAHA decreased the half-life of cyclin D1 mRNA from 6.95 h to 2.57 h. Consistent with downregulation of cyclin D1 mRNA stability, SAHA treatment also attenuated HuR expression, which has been well-characterized as a positive regulator of cyclin D1 mRNA stability. Thus, our study identifies a novel mechanism responsible for SAHA inhibiting cell transformation via decreasing cyclin D1 mRNA stability and induction of G0/G1 growth arrest in Cl41 cells. -- Highlights: ► SAHA inhibits cell transformation in Cl41 cells. ► SAHA suppresses Cyclin D1 protein expression. ► SAHA decreases cyclin D1 mRNA stability.

  20. The nucleation of austenite in ferritic ductile cast iron

    International Nuclear Information System (INIS)

    Chou, J.M.; Hon, M.H.; Lee, J.L.

    1992-01-01

    Austempered ductile cast iron has recently been receiving increasing attention because of its excellent combination of strength and ductility. Since the austenitization process has a significant influence on the mechanical properties of austempered ductile cast iron, several investigations on the nucleation sites of austenite and diffusion paths of carbon from spheroidal graphite have been reported in ferritic ductile cast iron. However, agreement on this subject has not ben reached. The purpose of this paper is to study the preferential nucleation sites of austenite during austenitization at two austenitizing temperatures in ferritic ductile cast iron. An attempt was made to understand the reasons which give rise to preferential austenite nucleation sites. The carbon diffusion paths from spheroidal graphite were also investigated

  1. Estimation scheme for unstable ductile fracture of pressure vessel

    International Nuclear Information System (INIS)

    Takahashi, Jun; Okamura, Hiroyuki; Sakai, Shinsuke

    1990-01-01

    This paper presents a new scheme for the estimation of unstable ductile fracture using the J-integral. The proposed method uses a load-versus-displacement diagram which is generated using fully plastic solutions. By this method, the phenomena of the ductile fracture can be grasped visually. Thus, the parametrical survey can be executed far more easily than before. Then, using the proposed method, unstable ductile fracture is analyzed for single-edge cracked plates under both uniform tension and pure bending. In addition, several parametrical surveys are performed concerning (1) J-controlled crack growth, (2) compliance of the structure, (3) ductility of the material (i.e., J-resistance curve), and (4) scale of the structure (i.e., screening criterion). As a result, it is shown that the proposed method is especially effective for the paramtrical study of unstable ductile fracture. (author)

  2. Fracture of longitudinally cracked ductile tubes

    International Nuclear Information System (INIS)

    Larsson, H.; Bernard, J.

    1978-01-01

    Various bulging factor and plasticity correction factor formulations are discussed and a new plasticity correction factor leading to a simple failure law is proposed. Failure stresses predicted by the usual Linear Elastic Fracture Mechanics formula corrected for plasticity are shown to be identical with the Dowling and Townley two-criteria approach if the relevant parameters are chosen in a suitable manner. Burst tests on AISI 304 stainless steel tubes performed at the Joint Research Centre, Ispra are described. The strengthening effect of the sealing patch was taken into account by replacing the Folias bulging factor by a smaller empirical factor determined by Bernard and Henry from fatigue crack growth tests. A flow stress sigma and a toughness Ksub(c) were derived which apply to the prediction of the onset of stable crack growth in 304 stainless steel tubes at room temperature. For other ductile materials and temperatures tentative formulae are proposed. (author)

  3. A highly ductile magnesium alloy system

    International Nuclear Information System (INIS)

    Gao, W; Liu, H

    2009-01-01

    Magnesium (Mg) alloys are finding increasing applications in industry mainly due to their high strength-to-weight ratio. However, they have intrinsically poor plastic deformation ability at room temperature. Therefore, the vast majority of Mg alloys are used only in cast state, severely limiting the development of their applications. We have recently discovered a new Mg alloy system that possesses exceptionally high ductility as well as good mechanical strength. The superior plasticity allows this alloy system to be mechanically deformed at room temperature, directly from an as-cast alloy plate, sheet or ingot into working parts. This type of cold mechanical forming properties has never been reported with any other Mg alloy systems.

  4. Hot ductility testing and weld simulation tests

    International Nuclear Information System (INIS)

    Weber, G.; Schick, M.

    1999-01-01

    The objective of the project was to enhance the insight into the causes of intergranular cracks detected in austenitic circumferential welds at BWR pipes. The susceptibility of a variety of austenitic pipe materials to hot cracking during welding and in-service intergranular crack corrosion was examined. The assumption was cracking in the root area of the HAZ of a multiple-layer weld. Hot-ductility tests and weld simulation tests specifically designed for the project were performed with the austenitic LWR pipe materials 1.4553 (X6 CrNiNb 18 10 S), 1.4550 (X10 CrNiNb 18 9), 1.4533 (X6 CrNiTi 18 9, two weld pools), and a non-stabilized TP 304 (X5 CrNi 18 10). (orig./CB) [de

  5. Quantifying Damage Accumulation During Ductile Plastic Deformation Using Synchrotron Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Suter, Robert M. [Carnegie Mellon Univ., Pittsburgh, PA (United States); Rollett, Anthony D. [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    2015-08-15

    Under this grant, we have developed and demonstrated the ability of near-field High Energy Diffraction Microscopy (nf-HEDM) to map crystal orientation fields over three dimensions in deformed polycrystalline materials. Experimental work was performed at the Advanced Photon Source (APS) at beamline 1-ID. Applications of this new capability to ductile deformation of copper and zirconium samples were demonstrated as was the comparison of the experimental observations to computational plasticity models using a fast Fourier transform based algorithm that is able to handle the large experimental data sets. No such spatially resolved, direct comparison between measured and computed microstructure evolutions had previously been possible. The impact of this work is reflected in numerous publications and presentations as well as in the investments by DOE and DOD laboratories of millions of dollars in applying the technique, developing sophisticated new hardware that allows the technique to be applied to a wide variety of materials and materials problems, and in the use of the technique by other researchers. In essence, the grant facilitated the development of a new form of three dimensional microscopy and its application to technologically critical states of polycrystalline materials that are used throughout the U.S. and world economies. On-going collaborative work is further optimizing experimental and computational facilities at the APS and is pursuing expanded facilities.

  6. A diffraction based study of the deformation mechanisms in anomalously ductile B2 intermetallics

    Science.gov (United States)

    Mulay, Rupalee Prashant

    For many decades, the brittle nature of most intermetallic compounds (e.g. NiAl) has been the limiting factor in their practical application. Many B2 (CsCl prototypical structure) intermetallics are known to exhibit slip on the {110} slip mode, which provides only 3 independent slip systems and, hence, is unable to satisfy the von Mises (a.k.a. Taylor) criterion for polycrystalline ductility. As a result, inherent polycrystalline ductility is unexpected. Recent discovery of a number of ductile B2 intermetallics has raised questions about possible violation of the von Mises criterion by these alloys. These ductile intermetallic compounds are MR (metal (M) combined with a rare earth metal or group IV refractory metal (R)) alloys and are stoichiometric, ordered compounds. Single crystal slip trace analyses have only identified the presence of {011} or {010} slip systems. More than 100 other B2 MR compounds are known to exist and many of them have already been shown to be ductile (e.g., CuY, AgY, CuDy, CoZr, CoTi, etc.). Furthermore, these alloys exhibit a large Bauschinger effect. The present work uses several diffraction based techniques including electron back scattered diffraction (EBSD), X-ray diffraction (XRD) and in-situ neutron diffraction; in conjunction with scanning electron microscopy (SEM), transmission electron microscopy (TEM), mechanical testing, and crystal plasticity modeling, to elucidate the reason for ductility in select B2 alloys, explore the spread of this ductility over the B2 family, and understand the Bauschinger effect in these alloys. Several possible explanations (e.g., slip of dislocations, strong texture, phase transformations and twinning) for the anomalous ductility were explored. An X-ray diffraction based analysis ruled out texture, phase purity and departure from order as explanations for the anomalous ductility in MR alloys. In-situ neutron diffraction and post deformation SEM, EBSD, and TEM were unable to detect any evidence for

  7. Epithelial–mesenchymal transition during oncogenic transformation induced by hexavalent chromium involves reactive oxygen species-dependent mechanism in lung epithelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Song-Ze, E-mail: dingsongze@hotmail.com [Department of Internal Medicine, Henan Provincial People’s Hospital, Zhengzhou University, Wei-Wu Road, Zhengzhou, Henan 450000 (China); Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536 (United States); Yang, Yu-Xiu; Li, Xiu-Ling [Department of Internal Medicine, Henan Provincial People’s Hospital, Zhengzhou University, Wei-Wu Road, Zhengzhou, Henan 450000 (China); Michelli-Rivera, Audrey [Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536 (United States); Han, Shuang-Yin [Department of Internal Medicine, Henan Provincial People’s Hospital, Zhengzhou University, Wei-Wu Road, Zhengzhou, Henan 450000 (China); Wang, Lei; Pratheeshkumar, Poyil; Wang, Xin; Lu, Jian; Yin, Yuan-Qin; Budhraja, Amit; Hitron, Andrew J. [Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536 (United States)

    2013-05-15

    Hexavalent chromium [Cr(VI)] is an important human carcinogen associated with pulmonary diseases and lung cancer. Exposure to Cr(VI) induces DNA damage, cell morphological change and malignant transformation in human lung epithelial cells. Despite extensive studies, the molecular mechanisms remain elusive, it is also not known if Cr(VI)-induced transformation might accompany with invasive properties to facilitate metastasis. We aimed to study Cr(VI)-induced epithelial–mesenchymal transition (EMT) and invasion during oncogenic transformation in lung epithelial cells. The results showed that Cr(VI) at low doses represses E-cadherin mRNA and protein expression, enhances mesenchymal marker vimentin expression and transforms the epithelial cell into fibroblastoid morphology. Cr(VI) also increases cell invasion and promotes colony formation. Further studies indicated that Cr(VI) uses multiple mechanisms to repress E-cadherin expression, including activation of E-cadherin repressors such as Slug, ZEB1, KLF8 and enhancement the binding of HDAC1 in E-cadherin gene promoter, but DNA methylation is not responsible for the loss of E-cadherin. Catalase reduces Cr(VI)-induced E-cadherin and vimentin protein expression, attenuates cell invasion in matrigel and colony formation on soft agar. These results demonstrate that exposure to a common human carcinogen, Cr(VI), induces EMT and invasion during oncogenic transformation in lung epithelial cells and implicate in cancer metastasis and prevention. - Graphical abstract: Epithelial–mesenchymal transition during oncogenic transformation induced by hexavalent chromium involves reactive oxygen species-dependent mechanisms in lung epithelial cells. - Highlights: • We study if Cr(VI) might induce EMT and invasion in epithelial cells. • Cr(VI) induces EMT by altering E-cadherin and vimentin expression. • It also increases cell invasion and promotes oncogenic transformation. • Catalase reduces Cr(VI)-induced EMT, invasion and

  8. Influence of strain-induced martensitic transformation on fatigue short crack behaviour in an austenitic stainless steel

    International Nuclear Information System (INIS)

    Baffie, N.; Stolarz, J.; Magnin, Th.

    2000-01-01

    The influence of martensitic transformation induced by cyclic straining on the mechanisms of low cycle fatigue damage in a metastable austenitic stainless steel with different grain sizes has been investigated using macroscopic measurements and microscopic observations of short crack evolutions. The amount of martensite formed during cyclic straining increases with increasing plastic strain amplitude and cumulative plastic strain but the dominant parameter is the grain size of austenite. The fine microstructure (D = 10 μm) with maximum martensite fraction of about 20% is characterised by a better fatigue resistance than the coarse one (D 40μm and only 2% of martensite) for the same plastic strain amplitude. Martensitic transformation is found to radically modify the cyclic response of the alloy and consequently the damage mechanisms. Indeed, both short crack nucleation and growth take place exclusively in the transformed regions. A mechanism of short crack propagation based on the γ→ α' transformation assisted by stress concentration at the crack tip is proposed. The indirect influence of grain boundaries in the austenite on crack propagation in the martensite is demonstrated. The better fatigue resistance of metastable alloys with fine granular structure can thus be understood. (authors)

  9. Misoprostol-induced radioprotection of Syrian hamster embryo cells in utero from cell death and oncogenic transformation

    International Nuclear Information System (INIS)

    Miller, R.C.; LaNasa, P.; Hanson, W.R.

    1994-01-01

    Misoprostol, a PGE analog, is an effective radioprotector of murine intestine and hematopoietic and hair cell renewal systems. The radioprotective nature of misoprostol was extended to examine its ability to influence clonogenic cell survival and induction of oncogenic transformation in Syrian hamster embryo cells exposed to X rays in utero and assayed in vitro. Hamsters in their 12th day of pregnancy were injected subcutaneously with misoprostal, and 2 h later the pregnant hamsters were exposed to graded doses of X rays. Immediately after irradiation, hamsters were euthanized and embryonic tissue was explanted into culture dishes containing complete growth medium. After a 2-week incubation period, clongenic cell survival and morphologically transformed foci were determined. Survival of misoprostol-treated SHE cells was increased and yielded a dose reduction factor of 1.5 compared to SHE cells treated with X rays alone. In contrast, radiation-induced oncogenic transformation of misoprostol-treated cells was reduced by a factor of 20 compared to cells treated with X rays alone. These studies suggest that misoprostol not only protects normal tissues in vivo from acute radiation injury, but also protects cells, to a large extent, from injury leading to transforming events. 26 refs., 6 figs., 2 tabs

  10. Analysis of neutron diffraction spectra acquired in situ during stress-induced transformations in superelastic NiTi

    International Nuclear Information System (INIS)

    Vaidyanathan, R.; Bourke, M.A.; Dunand, D.C.

    1999-01-01

    Neutron diffraction spectra were obtained during various stages of a reversible stress-induced austenite to martensite phase transformation in superelastic NiTi. This was accomplished by neutron diffraction measurements on bulk polycrystalline NiTi samples simultaneously subjected to mechanical loading. Analysis of the data was carried out using individual lattice plane (hkl) reflections as well as by Rietveld refinement. In the Rietveld procedure, strains in austenite were described in terms of an isotropic (hkl independent) and an anisotropic (hkl dependent) component. At higher stresses, austenite lattice plane reflections exhibited nonlinear and dissimilar elastic responses which may be attributed to the transformation. The texture evolution is significant in both austenite and martensite phases during the transformation and two approaches were used to describe this evolving texture, i.e., an ellipsoidal model due to March - Dollase and a generalized spherical-harmonic approach. The respective predictions of the phase fraction evolution as a function of applied stress were compared. A methodology is thus established to quantify the discrete phase strains, phase volume fractions, and texture during such transformations. copyright 1999 American Institute of Physics

  11. Chromosome alterations in the X-ray-induced transformants of cultured mouse cell line

    International Nuclear Information System (INIS)

    Kodama, Seiji; Komatsu, Kenshi; Okumura, Yutaka; Sasaki, M.S.

    1989-01-01

    Mouse m5S cells were subjected to soft X-ray irradiation. Twenty-four transformants were separated as indicators of focus formation. Two clones, cl.4103 and cl.6310, were chosen for the analysis of chromosome alterations in transformants. A parent strain, m5S/1M, served as the control. Anchorage independence (AG) was not detected in the control strain, irrespective of culture conditions and population doubling number (PDN). In the case of transformants, the frequency of AG was increased with increasing PDN for cl.4103, and was constant for cl.6310, irrespective of PDN. Karyotype of m5S/1M was 42, X, -Y, +der (6) t(6;13), t(8;8), +8, +15. In addition, -13, der(10) and -der(6)t(6;13), der(5), +mar occurred as karyotype alterations for cl.4103 and cl. 6310, respectively. The present experiment indicated that chromosome alterations secondary to primary alterations occur in a high frequency in the transforming process of X-ray irradiated cells, and that the secondary chromosome alterations result in selective proliferation of transformed clones. (Namekawa, K)

  12. Nature of gallium focused ion beam induced phase transformation in 316L austenitic stainless steel

    International Nuclear Information System (INIS)

    Babu, R. Prasath; Irukuvarghula, S.; Harte, A.; Preuss, M.

    2016-01-01

    The microstructural evolution and chemistry of the ferrite phase (α), which transforms from the parent austenite phase (γ) of 316L stainless steel during gallium (Ga) ion beam implantation in Focused Ion Beam (FIB) instrument was systematically studied as a function of Ga"+ ion dose and γ grain orientations. The propensity for initiation of γ → α phase transformation was observed to be strongly dependent on the orientation of the γ grain with respect to the ion beam direction and correlates well with the ion channelling differences in the γ orientations studied. Several α variants formed within a single γ orientation and the sputtering rate of the material, after the γ → α transformation, is governed by the orientation of α variants. With increased ion dose, there is an evolution of orientation of the α variants towards a variant of higher Ga"+ channelling. Unique topographical features were observed within each specific γ orientation that can be attributed to the orientation of defects formed during the ion implantation. In most cases, γ and α were related by either Kurdjumov-Sachs (KS) or Nishiyama-Wassermann (NW) orientation relationship (OR) while in few, no known OR's were identified. While our results are consistent with gallium enrichment being the cause for the γ → α phase transformation, some observations also suggest that the strain associated with the presence of gallium atoms in the lattice has a far field stress effect that promotes the phase transformation ahead of gallium penetration.

  13. Effects of chloride ions on corrosion of ductile iron and carbon steel in soil environments.

    Science.gov (United States)

    Song, Yarong; Jiang, Guangming; Chen, Ying; Zhao, Peng; Tian, Yimei

    2017-07-31

    Chloride is reported to play a significant role in corrosion reactions, products and kinetics of ferrous metals. To enhance the understanding of the effects of soil environments, especially the saline soils with high levels of chloride, on the corrosion of ductile iron and carbon steel, a 3-month corrosion test was carried out by exposing ferrous metals to soils of six chloride concentrations. The surface morphology, rust compositions and corrosion kinetics were comprehensively studied by visual observation, scanning electron microscopy (SEM), X-Ray diffraction (XRD), weight loss, pit depth measurement, linear polarization and electrochemical impedance spectroscopy (EIS) measurements. It showed that chloride ions influenced the characteristics and compositions of rust layers by diverting and participating in corrosion reactions. α-FeOOH, γ-FeOOH and iron oxides were major corrosion products, while β-Fe 8 O 8 (OH) 8 Cl 1.35 rather than β-FeOOH was formed when high chloride concentrations were provided. Chloride also suppressed the decreasing of corrosion rates, whereas increased the difficulty in the diffusion process by thickening the rust layers and transforming the rust compositions. Carbon steel is more susceptible to chloride attacks than ductile iron. The corrosion kinetics of ductile iron and carbon steel corresponded with the probabilistic and bilinear model respectively.

  14. Raman studies of pressure and temperature induced phase transformations in calcite

    International Nuclear Information System (INIS)

    Exarhos, G.J.; Hess, N.J.

    1992-01-01

    This patent describes phase stability in the calcium carbonate system investigated as a simultaneous function of pressure and temperature up to 40 kbar and several hundred degrees Kelvin. Micro-Raman techniques were used to interrogate samples constrained within a resistively heated diamond anvil cell. Measured spectra allow unequivocal identification of crystalline phases and are used to refine the P,T phase diagram. Calcium carbonate was found to exhibit both reversible and irreversible transformation phenomena among the four known phases which exist under these conditions. Time-dependent Raman intensity variations as the material is perturbed from its equilibrium state allow real-time kinetics measurements to be performed. Evidence suggests that the order of certain observed transformations may be pressure dependent. The utility of Raman spectroscopy to follow transformation phenomena and to estimate fundamental thermophysical properties from the stress dependence of vibrational mode frequencies is demonstrated

  15. pH-Induced transformation of ligated Au25 to brighter Au23 nanoclusters.

    Science.gov (United States)

    Waszkielewicz, Magdalena; Olesiak-Banska, Joanna; Comby-Zerbino, Clothilde; Bertorelle, Franck; Dagany, Xavier; Bansal, Ashu K; Sajjad, Muhammad T; Samuel, Ifor D W; Sanader, Zeljka; Rozycka, Miroslawa; Wojtas, Magdalena; Matczyszyn, Katarzyna; Bonacic-Koutecky, Vlasta; Antoine, Rodolphe; Ozyhar, Andrzej; Samoc, Marek

    2018-05-01

    Thiolate-protected gold nanoclusters have recently attracted considerable attention due to their size-dependent luminescence characterized by a long lifetime and large Stokes shift. However, the optimization of nanocluster properties such as the luminescence quantum yield is still a challenge. We report here the transformation of Au25Capt18 (Capt labels captopril) nanoclusters occurring at low pH and yielding a product with a much increased luminescence quantum yield which we have identified as Au23Capt17. We applied a simple method of treatment with HCl to accomplish this transformation and we characterized the absorption and emission of the newly created ligated nanoclusters as well as their morphology. Based on DFT calculations we show which Au nanocluster size transformations can lead to highly luminescent species such as Au23Capt17.

  16. Cellular shear stiffness reflects progression of arsenic-induced transformation during G1

    DEFF Research Database (Denmark)

    Muñoz, Alexandra; Eldridge, Will J; Jakobsen, Nina Munkholt

    2017-01-01

    epithelial cells were exposed to sodium arsenite to initiate early stages of transformation. Exposed cells were cultured in soft agar to further transformation and select for clonal populations exhibiting anchorage independent growth. Shear stiffness of various cell populations in G1 was assessed using...... reduced stiffness relative to control clonal lines, which were cultured in soft agar but did not receive arsenic treatment. The relative standard deviation of the stiffness of Arsenic clones was reduced compared to control clones, as well as to the arsenic exposed cell population. Cell stiffness...

  17. Nucleobase-Based Barbiturates: Their Protective Effect against DNA Damage Induced by Bleomycin-Iron, Antioxidant, and Lymphocyte Transformation Assay

    Directory of Open Access Journals (Sweden)

    Bhaveshkumar D. Dhorajiya

    2014-01-01

    Full Text Available A number of nucleobase-based barbiturates have been synthesized by combination of nucleic acid bases and heterocyclic amines and barbituric acid derivatives through green and efficient multicomponent route and one pot reaction. This approach was accomplished efficiently using aqueous medium to give the corresponding products in high yield. The newly synthesized compounds were characterized by spectral analysis (FT-IR, 1H NMR, 13C NMR, HMBC, and UV spectroscopy and elemental analysis. Representative of all synthesized compounds was tested and evaluated for antioxidant, bleomycin-dependent DNA damage, and Lymphocyte Transformation studies. Compounds TBC > TBA > TBG showed highest lymphocyte transformation assay, TBC > TBA > BG showed inhibitory antioxidant activity using ABTS methods, and TBC > BPA > BAMT > TBA > 1, 3-TBA manifested the best protective effect against DNA damage induced by bleomycin.

  18. Determination of Trace Available Heavy Metals in Soil Using Laser-Induced Breakdown Spectroscopy Assisted with Phase Transformation Method.

    Science.gov (United States)

    Yi, Rongxing; Yang, Xinyan; Zhou, Ran; Li, Jiaming; Yu, Huiwu; Hao, Zhongqi; Guo, Lianbo; Li, Xiangyou; Lu, Yongfeng; Zeng, Xiaoyan

    2018-05-18

    To detect available heavy metals in soil using laser-induced breakdown spectroscopy (LIBS) and improve its poor detection sensitivity, a simple and low cost sample pretreatment method named solid-liquid-solid transformation was proposed. By this method, available heavy metals were extracted from soil through ultrasonic vibration and centrifuging and then deposited on a glass slide. Utilization of this solid-liquid-solid transformation method, available Cd and Pb elements in soil were detected successfully. The results show that the regression coefficients of calibration curves for soil analyses reach to more than 0.98. The limits of detection could reach to 0.067 and 0.94 ppm for available Cd and Pb elements in soil under optimized conditions, respectively, which are much better than those obtained by conventional LIBS.

  19. Shock wave induced martensitic transformations and morphology changes in Fe-Pd ferromagnetic shape memory alloy thin films

    International Nuclear Information System (INIS)

    Bischoff, A. J.; Arabi-Hashemi, A.; Ehrhardt, M.; Lorenz, P.; Zimmer, K.; Mayr, S. G.

    2016-01-01

    Combining experimental methods and classical molecular dynamics (MD) computer simulations, we explore the martensitic transformation in Fe_7_0Pd_3_0 ferromagnetic shape memory alloy thin films induced by laser shock peening. X-ray diffraction and scanning electron microscope measurements at shock wave pressures of up to 2.5 GPa reveal formation of martensitic variants with preferred orientation of the shorter c-axis of the tetragonal unit cell perpendicular to the surface plane. Moreover, consequential merging of growth islands on the film surface is observed. MD simulations unveil the underlying physics that are characterized by an austenite-martensite transformation with a preferential alignment of the c-axis along the propagation direction of the shock wave, resulting in flattening and in-plane expansion of surface features.

  20. Ductility and microstructure of precipitation-strengthened alloys irradiated in HFIR

    International Nuclear Information System (INIS)

    Yang, W.J.S.; Hamilton, M.L.

    1983-08-01

    Six γ' and γ'/γ'' strengthened Ni-base alloys have shown near-zero ductility after irradiation at 300 to 600 0 C in HFIR to a peak exposure of 9 dpa. Microstructural examination of the irradiated specimens showed that the loss of ductility in these alloys arises from the simultaneous existence of a strong matrix and weak grain boundaries. The strong matrix is attributed to the irradiation-induced γ' and γ'/γ'' precipitates, the faulted loops and a high density of fine helium bubbles. The weak grain boundaries are attributed to the formation of an unfavorable precipitate, such as eta-plates, recrystallized grains, a thin layer of γ' and helium bubbles

  1. Unstable ductile fracture conditions in upper shelf region

    International Nuclear Information System (INIS)

    Nakano, Yoshifumi; Kubo, Takahiro

    1985-01-01

    The phenomenon of unstability of ductile fracture in the upper shelf region of a forged steel for nuclear reactor pressure vessels A508 Cl. 3 was studied with a large compliance apparatus, whose spring constants were 100, 170 and 230 kgf/mm, at the test temperatures of 100, 200 and 300 0 C and at the loading rates of 2, 20 and 200 mm/min in the crosshead speed. The main results obtained are as follows: (1) The fracture modes of the specimens consisted of (a) stable fracture, (b) unstable fracture which leads to a complete fracture rapidly and (c) quasiunstable fracture which does not lead to a complete fracture though a rapid extension of ductile crack takes place. (2) Side groove, high temperature or small spring constant made a ductile crack more unstable. (3) High temperature or large spring constant made the occurrence of quasiunstable fracture easier. (4) Quasiunstable ductile fracture took place before the maximum load, that is, at the J integral value of about 10 kgf/mm. The initiation of a microscopic ductile crack, therefore, seems to lead to quasiunstable fracture. (5) The concept that unstable ductile fracture takes place when Tsub(app) exceeds Tsub(mat) seems applicable only to the case in which unstable ductile fracture takes place after the maximum load has been exceeded. (author)

  2. Effects of dead load on ductility of a floor system

    International Nuclear Information System (INIS)

    Fujisaki, E.; Sarkar, B.E.; Ho, H.; Reed, J.W.

    1993-01-01

    In seismic margin or seismic fragility calculations, the ductility scale factor F μ is often used to quantify the effect of inelastic energy absorption on structural capacity. In concept, the ductility scale factor can be thought of as a response spectrum reduction factor. For a given ductile structural element and input response spectrum, the product of F μ and the factor of safety against yield (F s ) provides a measure of the total factor of safety against failure (F). Testing and analytical studies by others have shown that structures such as shear walls and building frames (mounted vertically) subjected to horizontal input motions are capable of absorbing earthquake energy through inelastic behavior. Kennedy, 1984, Riddell, 1979, and Reed, 1991 studied the ductility scale factor and developed simplified procedures through the use of nonlinear analyses. For floor systems (mounted horizontally), we are mainly interested in the response to vertical input motions. Because of the constant downward pull of gravity, the nonlinear displacement of a floor structure is biased downward. This ratcheting phenomenon reduces the ductility scale factor for a horizontal element compared to the case where the same element is mounted vertically and is subjected to horizontal input motion. Through the use of nonlinear time history analyses, we investigated the effects of dead loads on the ductility scale factor of floor systems. We also developed a simple modification to the Riddell-Newmark procedure (Riddell, 1979), which is used to calculate the ductility scale factor for vertically mounted elements, to determine F μ for horizontally mounted elements

  3. Hot Ductility Behavior of a Peritectic Steel during Continuous Casting

    Directory of Open Access Journals (Sweden)

    Mustafa Merih Arıkan

    2015-06-01

    Full Text Available Hot ductility properties of a peritectic steel for welded gas cylinders during continuous casting were studied by performing hot tensile tests at certain temperatures ranging from 1200 to 700 °C for some cooling rates by using Gleeble-3500 thermo-mechanical test and simulation machine in this study. The effects of cooling rate and strain rate on hot ductility were investigated and continuous casting process map (time-temperature-ductility were plotted for this material. Reduction of area (RA decreases and cracking susceptibility increases during cooling from solidification between certain temperatures depending on the cooling rate. Although the temperatures which fracture behavior change upon cooling during continuous casting may vary for different materials, it was found that the type of fracture was ductile at 1100 and 1050 °C; semi-ductile at 1000 °C, and brittle at 800 °C for the steel P245NB. There is a ductility trough between 1000 and 725 °C. The ductility trough gets slightly narrower as the cooling rate decreases.

  4. FeII induced mineralogical transformations of ferric oxyhydroxides into magnetite of variable stoichiometry and morphology

    International Nuclear Information System (INIS)

    Usman, M.; Abdelmoula, M.; Hanna, K.

    2012-01-01

    The Mössbauer spectroscopy was used to monitor the mineralogical transformations of ferrihydrite (F), lepidocrocite (L) and goethite (G) into magnetite as a function of aging time. Ferric oxyhydroxides were reacted with soluble Fe II and OH – in stoichiometric amounts to form magnetite at an initial pH of ∼9.7. Observed transformation extent into magnetite followed the order: F>L>G with almost 30% of untransformed G after 1 month. The departure from stoichiometry, δ, of magnetite (Fe 3−δ O 4 ) generated from F (δ∼0.04) and L (δ∼0.05) was relatively low as compared to that in magnetite from G (δ∼0.08). The analysis by transmission electron microscopy and BET revealed that generated magnetite was also different in terms of morphology, particle size and surface area depending on the nature of initial ferric oxyhydroxide. This method of preparation is a possible way to form nano-sized magnetite. - Graphical abstract: Mössbauer spectrum of the early stage of magnetite formation formed from the interaction of adsorbed Fe II species with goethite. Highlights: ► Ferric oxides were reacted with hydroxylated Fe II to form magnetite. ► Magnetite formation was quantified as a function of aging time. ► Complete transformation of ferrihydrite and lepidocrocite was achieved. ► Almost 70% of initial goethite was transformed. ► Resulting magnetites have differences in stoichiometry and morphological properties.

  5. Stress induced martensitic transformations in tension/torsion of CuAlNi single crystal tube

    Czech Academy of Sciences Publication Activity Database

    Šittner, Petr; Hashimoto, K.; Kato, M.; Tokuda, M.

    2003-01-01

    Roč. 48, - (2003), s. 1153-1159 ISSN 1359-6462 R&D Projects: GA AV ČR IAA1048107 Institutional research plan: CEZ:AV0Z1010914 Keywords : shape memory alloys(SMAs) * martensitic phase transformation * single crystal tube * tension test * torsion Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.633, year: 2003

  6. Pressure-induced structural transformations in the molybdate Sc-2(MoO4)(3)

    DEFF Research Database (Denmark)

    Paraguassu, W.; Maczka, M.; Filho, A. G. Sonza

    2004-01-01

    High pressure Raman scattering and x-ray diffraction studies of the molybdate Sc-2(MoO4)(3) are presented. A sequence of changing symmetry effects is observed through two structural phase transitions ending up with an amorphous state. The observed two structural phase transformations are reversible...

  7. X-ray-induced in vitro neoplastic transformation of human diploid cells

    International Nuclear Information System (INIS)

    Borek, C.

    1980-01-01

    The neoplastic transformation, in vitro, of human diploid cells by x-ray irradiation into cells which can progress, in vitro, into advanced stages of neoplastic development is described. The cells are shown to form colonies in agar and to give rise to tumours when injected into nude mice. (U.K.)

  8. Pressure-induced phase transformations in the Ba8Si46 clathrate

    DEFF Research Database (Denmark)

    Yang, Lirong; Ma, Y.M.; Iitaka, T.

    2006-01-01

    The nature of isostructural transformations of a type-I Ba8Si46 clathrate has been studied by in situ high-pressure angle-dispersive x-ray powder diffraction using liquid He as pressure transmitting medium. The good quality of the diffraction data permitted refinement of structural and thermal...

  9. Surface modification-induced phase transformation of hexagonal close-packed gold square sheets

    KAUST Repository

    Fan, Zhanxi

    2015-03-13

    Conventionally, the phase transformation of inorganic nanocrystals is realized under extreme conditions (for example, high temperature or high pressure). Here we report the complete phase transformation of Au square sheets (AuSSs) from hexagonal close-packed (hcp) to face-centered cubic (fcc) structures at ambient conditions via surface ligand exchange, resulting in the formation of (100)f-oriented fcc AuSSs. Importantly, the phase transformation can also be realized through the coating of a thin metal film (for example, Ag) on hcp AuSSs. Depending on the surfactants used during the metal coating process, two transformation pathways are observed, leading to the formation of (100)f-oriented fcc Au@Ag core-shell square sheets and (110)h/(101)f-oriented hcp/fcc mixed Au@Ag nanosheets. Furthermore, monochromated electron energy loss spectroscopy reveals the strong surface plasmon resonance absorption of fcc AuSS and Au@Ag square sheet in the infrared region. Our findings may offer a new route for the crystal-phase and shape-controlled synthesis of inorganic nanocrystals. © 2015 Macmillan Publishers Limited. All rights reserved.

  10. Grain size effects in multiphase steels assisted by transformation-induced plasticity

    NARCIS (Netherlands)

    Turteltaub, S.R.; Suiker, A.S.J.

    2006-01-01

    The influence of the austenitic grain size on the overall stress-strain behavior in a multiphase carbon steel is analyzed through three-dimensional finite element simulations. A recently developed multiscale martensitic transformation model is combined with a plasticity model to simulate the

  11. Ab initio study of pressure stabilized NiTi allotropes: Pressure-induced transformations

    Czech Academy of Sciences Publication Activity Database

    Holec, D.; Friák, M.; Dlouhý, Antonín; Neugebauer, J.

    2011-01-01

    Roč. 84, č. 22 (2011), 224119/1-224119/8 ISSN 1098-0121 Institutional research plan: CEZ:AV0Z20410507 Keywords : shape - memory alloys * martensitic transformations * local stability Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.691, year: 2011

  12. Surface modification-induced phase transformation of hexagonal close-packed gold square sheets

    KAUST Repository

    Fan, Zhanxi; Huang, Xiao; Han, Yu; Bosman, Michel; Wang, Qingxiao; Zhu, Yihan; Liu, Qing; Li, Bing; Zeng, Zhiyuan; Wu, Jumiati; Shi, Wenxiong; Li, Shuzhou; Gan, Chee Lip; Zhang, Hua

    2015-01-01

    Conventionally, the phase transformation of inorganic nanocrystals is realized under extreme conditions (for example, high temperature or high pressure). Here we report the complete phase transformation of Au square sheets (AuSSs) from hexagonal close-packed (hcp) to face-centered cubic (fcc) structures at ambient conditions via surface ligand exchange, resulting in the formation of (100)f-oriented fcc AuSSs. Importantly, the phase transformation can also be realized through the coating of a thin metal film (for example, Ag) on hcp AuSSs. Depending on the surfactants used during the metal coating process, two transformation pathways are observed, leading to the formation of (100)f-oriented fcc Au@Ag core-shell square sheets and (110)h/(101)f-oriented hcp/fcc mixed Au@Ag nanosheets. Furthermore, monochromated electron energy loss spectroscopy reveals the strong surface plasmon resonance absorption of fcc AuSS and Au@Ag square sheet in the infrared region. Our findings may offer a new route for the crystal-phase and shape-controlled synthesis of inorganic nanocrystals. © 2015 Macmillan Publishers Limited. All rights reserved.

  13. Conformational transformations induced by the charge-curvature interaction at finite temperature

    DEFF Research Database (Denmark)

    Gaididei, Yuri Borisovich; Gorria, Carlos; Christiansen, Peter Leth

    2008-01-01

    The role of thermal fluctuations on the conformational dynamics of a single closed filament is studied. It is shown that, due to the interaction between charges and bending degrees of freedom, initially circular aggregates may undergo transformation to polygonal shape. The transition occurs both...

  14. Mechanism of Process-Induced Salt-to-Free Base Transformation of Pharmaceutical Products

    DEFF Research Database (Denmark)

    Bruun Hansen, Thomas; Qu, Haiyan

    2014-01-01

    pH-solubility profiles of a model drug in salt form was established and the mechanism of salt-to-free base form transformation was investigated by increasing pH of the system. Wet massing experiments along with suspension experiments were used to investigate the effects of excipients on the stabi...

  15. Higher incidence of Epstein-Barr virus-induced lymphocyte transformation in multiple sclerosis

    DEFF Research Database (Denmark)

    Tørring, Caroline Winther; Andreasen, Charlotte; Gehr, Nikolaj

    2014-01-01

    Objectives Epstein–Barr virus (EBV) infection is associated with multiple sclerosis (MS), and EBV may transform lymphoblastoid cell lines more frequently in MS patients than controls, but it is not clear whether this reflects a higher viral load or an enhanced ability to reactivate EBV. Material...

  16. Pressure-induced transformations in glassy water: A computer simulation study using the TIP4P/2005 model

    Science.gov (United States)

    Wong, Jessina; Jahn, David A.; Giovambattista, Nicolas

    2015-08-01

    We study the pressure-induced transformations between low-density amorphous (LDA) and high-density amorphous (HDA) ice by performing out-of-equilibrium molecular dynamics (MD) simulations. We employ the TIP4P/2005 water model and show that this model reproduces qualitatively the LDA-HDA transformations observed experimentally. Specifically, the TIP4P/2005 model reproduces remarkably well the (i) structure (OO, OH, and HH radial distribution functions) and (ii) densities of LDA and HDA at P = 0.1 MPa and T = 80 K, as well as (iii) the qualitative behavior of ρ(P) during compression-induced LDA-to-HDA and decompression-induced HDA-to-LDA transformations. At the rates explored, the HDA-to-LDA transformation is less pronounced than in experiments. By studying the LDA-HDA transformations for a broad range of compression/decompression temperatures, we construct a "P-T phase diagram" for glassy water that is consistent with experiments and remarkably similar to that reported previously for ST2 water. This phase diagram is not inconsistent with the possibility of TIP4P/2005 water exhibiting a liquid-liquid phase transition at low temperatures. A comparison with previous MD simulation studies of SPC/E and ST2 water as well as experiments indicates that, overall, the TIP4P/2005 model performs better than the SPC/E and ST2 models. The effects of cooling and compression rates as well as aging on our MD simulations results are also discussed. The MD results are qualitatively robust under variations of cooling/compression rates (accessible in simulations) and are not affected by aging the hyperquenched glass for at least 1 μs. A byproduct of this work is the calculation of TIP4P/2005 water's diffusion coefficient D(T) at P = 0.1 MPa. It is found that, for T ≥ 210 K, D(T) ≈ (T - TMCT)-γ as predicted by mode coupling theory and in agreement with experiments. For TIP4P/2005 water, TMCT = 209 K and γ = 2.14, very close to the corresponding experimental values TMCT = 221 K

  17. X-ray diffraction study of thermally and stress-induced phase transformations in single crystalline Ni-Mn-Ga alloys

    International Nuclear Information System (INIS)

    Martynov, V.V.

    1995-01-01

    Using in-situ single crystal X-ray diffraction methods, thermally- and stress-induced crystal structure evolution was investigated in two Ni-Mn-Ga Heusler-type alloys. For the 51at.%Ni-24at.%Mn-25at.%Ga alloy it was found that application of external stress in a temperature range ∼20 C above the M s at first causes intensity changes of X-ray diffuse scattering peaks in β-phase. Further stressing results in stress-induced phase transformations and under the appropriate conditions three successive martensitic transformations (one is parent-to-martensite and two are martensite-to-martensite transformations) can be stress induced. Of these only the parent-to-martensite transformation can be thermally-induced. Two successive structural transformations (thermally-induced parent-to-martensite and stress-induced martensite-to-martensite transformations) were found in 52at.%Ni-25at.%Mn-23at.%Ga alloy. Crystal structure, lattice parameters, type of modulation, and the length of modulation period for all martensites were identified. (orig.)

  18. Heating-induced glass-glass and glass-liquid transformations in computer simulations of water

    Science.gov (United States)

    Chiu, Janet; Starr, Francis W.; Giovambattista, Nicolas

    2014-03-01

    Water exists in at least two families of glassy states, broadly categorized as the low-density (LDA) and high-density amorphous ice (HDA). Remarkably, LDA and HDA can be reversibly interconverted via appropriate thermodynamic paths, such as isothermal compression and isobaric heating, exhibiting first-order-like phase transitions. We perform out-of-equilibrium molecular dynamics simulations of glassy water using the ST2 model to study the evolution of LDA and HDA upon isobaric heating. Depending on pressure, glass-to-glass, glass-to-crystal, glass-to-vapor, as well as glass-to-liquid transformations are found. Specifically, heating LDA results in the following transformations, with increasing heating pressures: (i) LDA-to-vapor (sublimation), (ii) LDA-to-liquid (glass transition), (iii) LDA-to-HDA-to-liquid, (iv) LDA-to-HDA-to-liquid-to-crystal, and (v) LDA-to-HDA-to-crystal. Similarly, heating HDA results in the following transformations, with decreasing heating pressures: (a) HDA-to-crystal, (b) HDA-to-liquid-to-crystal, (c) HDA-to-liquid (glass transition), (d) HDA-to-LDA-to-liquid, and (e) HDA-to-LDA-to-vapor. A more complex sequence may be possible using lower heating rates. For each of these transformations, we determine the corresponding transformation temperature as function of pressure, and provide a P-T "phase diagram" for glassy water based on isobaric heating. Our results for isobaric heating dovetail with the LDA-HDA transformations reported for ST2 glassy water based on isothermal compression/decompression processes [Chiu et al., J. Chem. Phys. 139, 184504 (2013)]. The resulting phase diagram is consistent with the liquid-liquid phase transition hypothesis. At the same time, the glass phase diagram is sensitive to sample preparation, such as heating or compression rates. Interestingly, at least for the rates explored, our results suggest that the LDA-to-liquid (HDA-to-liquid) and LDA-to-HDA (HDA-to-LDA) transformation lines on heating are related

  19. Heating-induced glass-glass and glass-liquid transformations in computer simulations of water

    International Nuclear Information System (INIS)

    Chiu, Janet; Giovambattista, Nicolas; Starr, Francis W.

    2014-01-01

    Water exists in at least two families of glassy states, broadly categorized as the low-density (LDA) and high-density amorphous ice (HDA). Remarkably, LDA and HDA can be reversibly interconverted via appropriate thermodynamic paths, such as isothermal compression and isobaric heating, exhibiting first-order-like phase transitions. We perform out-of-equilibrium molecular dynamics simulations of glassy water using the ST2 model to study the evolution of LDA and HDA upon isobaric heating. Depending on pressure, glass-to-glass, glass-to-crystal, glass-to-vapor, as well as glass-to-liquid transformations are found. Specifically, heating LDA results in the following transformations, with increasing heating pressures: (i) LDA-to-vapor (sublimation), (ii) LDA-to-liquid (glass transition), (iii) LDA-to-HDA-to-liquid, (iv) LDA-to-HDA-to-liquid-to-crystal, and (v) LDA-to-HDA-to-crystal. Similarly, heating HDA results in the following transformations, with decreasing heating pressures: (a) HDA-to-crystal, (b) HDA-to-liquid-to-crystal, (c) HDA-to-liquid (glass transition), (d) HDA-to-LDA-to-liquid, and (e) HDA-to-LDA-to-vapor. A more complex sequence may be possible using lower heating rates. For each of these transformations, we determine the corresponding transformation temperature as function of pressure, and provide a P-T “phase diagram” for glassy water based on isobaric heating. Our results for isobaric heating dovetail with the LDA-HDA transformations reported for ST2 glassy water based on isothermal compression/decompression processes [Chiu et al., J. Chem. Phys. 139, 184504 (2013)]. The resulting phase diagram is consistent with the liquid-liquid phase transition hypothesis. At the same time, the glass phase diagram is sensitive to sample preparation, such as heating or compression rates. Interestingly, at least for the rates explored, our results suggest that the LDA-to-liquid (HDA-to-liquid) and LDA-to-HDA (HDA-to-LDA) transformation lines on heating are related

  20. Heating-induced glass-glass and glass-liquid transformations in computer simulations of water

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, Janet; Giovambattista, Nicolas [Department of Physics, Brooklyn College of the City University of New York, Brooklyn, New York 11210 (United States); Starr, Francis W. [Department of Physics, Wesleyan University, Middletown, Connecticut 06459 (United States)

    2014-03-21

    Water exists in at least two families of glassy states, broadly categorized as the low-density (LDA) and high-density amorphous ice (HDA). Remarkably, LDA and HDA can be reversibly interconverted via appropriate thermodynamic paths, such as isothermal compression and isobaric heating, exhibiting first-order-like phase transitions. We perform out-of-equilibrium molecular dynamics simulations of glassy water using the ST2 model to study the evolution of LDA and HDA upon isobaric heating. Depending on pressure, glass-to-glass, glass-to-crystal, glass-to-vapor, as well as glass-to-liquid transformations are found. Specifically, heating LDA results in the following transformations, with increasing heating pressures: (i) LDA-to-vapor (sublimation), (ii) LDA-to-liquid (glass transition), (iii) LDA-to-HDA-to-liquid, (iv) LDA-to-HDA-to-liquid-to-crystal, and (v) LDA-to-HDA-to-crystal. Similarly, heating HDA results in the following transformations, with decreasing heating pressures: (a) HDA-to-crystal, (b) HDA-to-liquid-to-crystal, (c) HDA-to-liquid (glass transition), (d) HDA-to-LDA-to-liquid, and (e) HDA-to-LDA-to-vapor. A more complex sequence may be possible using lower heating rates. For each of these transformations, we determine the corresponding transformation temperature as function of pressure, and provide a P-T “phase diagram” for glassy water based on isobaric heating. Our results for isobaric heating dovetail with the LDA-HDA transformations reported for ST2 glassy water based on isothermal compression/decompression processes [Chiu et al., J. Chem. Phys. 139, 184504 (2013)]. The resulting phase diagram is consistent with the liquid-liquid phase transition hypothesis. At the same time, the glass phase diagram is sensitive to sample preparation, such as heating or compression rates. Interestingly, at least for the rates explored, our results suggest that the LDA-to-liquid (HDA-to-liquid) and LDA-to-HDA (HDA-to-LDA) transformation lines on heating are related

  1. High velocity properties of the dynamic frictional force between ductile metals

    International Nuclear Information System (INIS)

    Hammerberg, James Edward; Hollan, Brad L.; Germann, Timothy C.; Ravelo, Ramon J.

    2010-01-01

    The high velocity properties of the tangential frictional force between ductile metal interfaces seen in large-scale NonEquilibrium Molecular Dynamics (NEMD) simulations are characterized by interesting scaling behavior. In many cases a power law decrease in the frictional force with increasing velocity is observed at high velocities. We discuss the velocity dependence of the high velocity branch of the tangential force in terms of structural transformation and ultimate transition, at the highest velocities, to confined fluid behavior characterized by a critical strain rate. The particular case of an Al/Al interface is discussed.

  2. Microstructure tailoring to enhance strength and ductility in Ti–13Nb–13Zr for biomedical applications

    International Nuclear Information System (INIS)

    Lee, Taekyung; Heo, Yoon-Uk; Lee, Chong Soo

    2013-01-01

    New microstructures were developed by strong grain refinement and phase control in a Ti–13Nb–13Zr alloy. Ultrafine-grained multiphase alloys were fabricated using a multipass caliber-rolling process at the (α + β) region. Transmission electron microscopy analysis revealed that different types of martensitic transformations occurred depending on the cooling rate. The developed alloys exhibited improved strength and ductility compared with a conventional material, and this enhancement of properties is discussed in terms of microstructural effects on the strain-hardening behavior

  3. Water structure versus radical scavenger theories as explanations for the suppressive effects of DMSO and related compounds on radiation-induced transformation in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, A.R.; Symons, M.C.

    1987-05-01

    We report here that dimethylsulfoxide (DMSO): suppresses radiation-induced transformation in vitro, even when DMSO treatments begin as late as 10 days post-irradiation (when cells are in the confluent, stationary phase of growth); inhibits the 12-O-tetradecanoylphorbol-13-acetate (TPA) enhancement of radiation-induced transformation in vitro; does not affect the expression of transformed cells as foci (when surrounded by non-transformed cells); and may be affecting radiation-induced transformation through its solvent properties (i.e. the Water Structure theory), while its effects on the TPA enhancement of radiation transformation may be mediated by its free radical scavenging abilities. DMSO, dimethylformamide (DMF) and dimethylacetamide (DMA) are similar solvents which are all very effective in their ability to suppress radiation-induced transformation in vitro (at concentrations in the cellular media down to 0.01%). As DMSO is known to be an extremely effective OH. free-radical scavenging agent, while DMF and DMA are not as efficient at scavenging free radicals, our results suggest that properties other than free-radical scavenging ability may be important in the suppressive effects of these compounds on radiation-induced transformation in vitro. It is known that low concentrations of such basic aprotic solvents modify water structure so as to suppress the protic (H-bond donor) reactivity of water and enhance its basic (H-bond receptor) reactivity. These reactivity changes may well be responsible for the effects noted above. DMSO, DMF and DMA are also capable of suppressing the TPA enhancement of radiation transformation (at concentrations of the compounds of 0.1% or higher). For this effect, the ability of these compounds to scavenge OH. shows a general correlation with their ability to suppress the TPA enhancement of transformation, suggesting that the Radical Scavenger theory may explain the ability of DMSO to suppress promotion in vitro.

  4. Sesquiterpene lactones isolated from indigenous Middle Eastern plants inhibit tumor promoter-induced transformation of JB6 cells

    Directory of Open Access Journals (Sweden)

    Saikali Melody

    2012-07-01

    Full Text Available Abstract Background Sesquiterpene lactones (SL are plant secondary metabolites that are known for their anti-fungal, anti-bacterial, anti-inflammatory, and anti-tumor properties. Considering that several SL-derived drugs are currently in cancer clinical trials, we have tested two SL molecules, 3-β-methoxy-iso-seco-tanapartholide (β-tan isolated from Achillea falcata and salograviolide A (Sal A isolated from Centaurea ainetensis, for their anti-tumor properties. We used the mouse epidermal JB6P + cells as a model for tumor promotion and cellular transformation. Key players that are involved in cellular transformation and tumorigenesis are the AP-1 and NF-κB transcription factors; therefore, we assessed how β-tan and Sal A modulate their signaling pathways in JB6P + cells. Methods The effects of β-tan and Sal A on the growth of normal and neoplastic keratinocytes and on the tumor promotion-responsive JB6P + cells were determined using the MTT assay. Anchorage-independent cell growth transformation assays were used to evaluate the anti-tumor promoting properties of these SL molecules in JB6P + cells and dual luciferase reporter assays and western blot analysis were used to investigate their effects on tumor promoter-induced AP-1 and NF-κB activities and protein levels of key AP-1 and NF-кB target genes. Results β-tan and Sal A selectively inhibited tumor promoter-induced cell growth and transformation of JB6P + cells at concentrations that do not affect JB6P + and primary keratinocytes basal cell growth. In addition, both molecules reduced basal and tumor promoter-induced NF-κB transcriptional activities, differentially regulated basal and tumor promoter-induced AP-1 transcriptional activities, and modulated key players of the AP-1 and NF-κB signaling pathways. Conclusions These results highlight the anti-tumor promoting properties of β-tan and Sal A. These SL molecules isolated from two plant species native to

  5. Sesquiterpene lactones isolated from indigenous Middle Eastern plants inhibit tumor promoter-induced transformation of JB6 cells.

    Science.gov (United States)

    Saikali, Melody; Ghantous, Akram; Halawi, Racha; Talhouk, Salma N; Saliba, Najat A; Darwiche, Nadine

    2012-07-09

    Sesquiterpene lactones (SL) are plant secondary metabolites that are known for their anti-fungal, anti-bacterial, anti-inflammatory, and anti-tumor properties. Considering that several SL-derived drugs are currently in cancer clinical trials, we have tested two SL molecules, 3-β-methoxy-iso-seco-tanapartholide (β-tan) isolated from Achillea falcata and salograviolide A (Sal A) isolated from Centaurea ainetensis, for their anti-tumor properties. We used the mouse epidermal JB6P + cells as a model for tumor promotion and cellular transformation. Key players that are involved in cellular transformation and tumorigenesis are the AP-1 and NF-κB transcription factors; therefore, we assessed how β-tan and Sal A modulate their signaling pathways in JB6P + cells. The effects of β-tan and Sal A on the growth of normal and neoplastic keratinocytes and on the tumor promotion-responsive JB6P + cells were determined using the MTT assay. Anchorage-independent cell growth transformation assays were used to evaluate the anti-tumor promoting properties of these SL molecules in JB6P + cells and dual luciferase reporter assays and western blot analysis were used to investigate their effects on tumor promoter-induced AP-1 and NF-κB activities and protein levels of key AP-1 and NF-кB target genes. β-tan and Sal A selectively inhibited tumor promoter-induced cell growth and transformation of JB6P + cells at concentrations that do not affect JB6P + and primary keratinocytes basal cell growth. In addition, both molecules reduced basal and tumor promoter-induced NF-κB transcriptional activities, differentially regulated basal and tumor promoter-induced AP-1 transcriptional activities, and modulated key players of the AP-1 and NF-κB signaling pathways. These results highlight the anti-tumor promoting properties of β-tan and Sal A. These SL molecules isolated from two plant species native to the Middle East may provide opportunities for complementary

  6. Identification Damage Model for Thermomechanical Degradation of Ductile Heterogeneous Materials

    Science.gov (United States)

    Amri, A. El; Yakhloufi, M. H. El; Khamlichi, A.

    2017-05-01

    The failure of ductile materials subject to high thermal and mechanical loading rates is notably affected by material inertia. The mechanisms of fatigue-crack propagation are examined with particular emphasis on the similarities and differences between cyclic crack growth in ductile materials, such as metals, and corresponding behavior in brittle materials, such as intermetallic and ceramics. Numerical simulations of crack propagation in a cylindrical specimen demonstrate that the proposed method provides an effective means to simulate ductile fracture in large scale cylindrical structures with engineering accuracy. The influence of damage on the intensity of the destruction of materials is studied as well.

  7. System Reliability of Timber Structures with Ductile Behaviour

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard; Čizmar, Dean

    2011-01-01

    The present paper considers the evaluation of timber structures with the focus on robustness due to connection ductility. The robustness analysis is based on the structural reliability framework applied to a simplified mechanical system. The structural timber system is depicted as a parallel system....... An evaluation method of the ductile behaviour is introduced. For different ductile behaviours, the system reliability is estimated based on Monte Carlo simulation. A correlation between the strength of the structural elements is introduced. The results indicate that the reliability of a structural timber system...

  8. High-temperature ductility of electro-deposited nickel

    Science.gov (United States)

    Dini, J. W.; Johnson, H. R.

    1977-01-01

    Work done during the past several months on high temperature ductility of electrodeposited nickel is summarized. Data are presented which show that earlier measurements made at NASA-Langley erred on the low side, that strain rate has a marked influence on high temperature ductility, and that codeposition of a small amount of manganese helps to improve high temperature ductility. Influences of a number of other factors on nickel properties were also investigated. They included plating solution temperature, current density, agitation, and elimination of the wetting agent from the plating solution. Repair of a large nozzle section by nickel plating is described.

  9. Modulation of cisplatin-induced reactive oxygen species production by fullerene C(60 in normal and transformed lymphoid cells

    Directory of Open Access Journals (Sweden)

    D. V. Franskevych

    2016-02-01

    Full Text Available The early response of normal (Wistar rat thymocytes and transformed (mice lymphoid leukemia L1210 cells to treatment with anticancer drug cisplatin or to combined treatment with cisplatin and carbon nanostructure fullerene C60 was studied. We demonstrated with fluorescent probes DCFH-DA and TMRE that cisplatin at concentration 1 μg/ml induced reactive oxygen species (ROS production and decreased the value of mitochondrial membrane potential in both cell types. The combined treatment with cisplatin (1 μg/ml and fullerene C60 (7.2 μg/ml was shown to be followed by oppositely directed modulation of ROS production in thymocytes and L1210 cells. Cisplatin-induced ROS production was intensified in L1210 cells, while in thymocytes it was decreased. It is supposed that the different effects of combined treatment are associated with peculiarities of fullerene C60 accumulation and localization in normal and cancer cells.

  10. Deformation-induced martensitic transformation in a 201 austenitic steel: The synergy of stacking fault energy and chemical driving force

    Energy Technology Data Exchange (ETDEWEB)

    Moallemi, M., E-mail: m.moallemi@ma.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Kermanpur, A. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Najafizadeh, A. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Fould Institute of Technology, Fouladshahr, Isfahan, 8491663763 (Iran, Islamic Republic of); Rezaee, A.; Baghbadorani, H. Samaei; Nezhadfar, P. Dastranjy [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2016-01-20

    The present study deals with the correlation of stacking fault energy's synergy and driving force in the formation of deformation-induced martensitic transformation in a 201 austenitic stainless steel. The fraction of deformation-induced martensite was characterized by means of X-ray diffraction and magnetic induction techniques. The kinetics of the martensite formation versus applied strain was evaluated through the sigmoidal model. It was shown that the volume fraction of ά-martensite is closely related to the driving force/SFE ratio of the alloy. The results also showed that the martensite content is similar in both XRD and magnetic methods and the applied sigmoidal model was consistent with the obtained experimental data.

  11. Anneal-induced transformations in the transport and magnetic properties of CoCu granulars

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, M.G.M. E-mail: mari@if.ufrgs.br; Antunes, A.B.; Bracho Rodriguez, G.J.; Baibich, M.N

    2001-05-01

    The electrical and magnetic properties of granular Co{sub 5}Cu{sub 95}, Co{sub 10}Cu{sub 90} and Co{sub 15}Cu{sub 85} ribbons treated with different annealing procedures were measured from helium to room temperatures. The isochronous anneals had fixed heating rate and the transformations were followed by 'in situ' resistivity measurements. We found that the transformation occurs at nearly the same region of temperature for the three compositions. Besides, our results for magnetoresistance on Co{sub 10}Cu{sub 90} could be understood in the light of the re-dissolution of Co into the Cu matrix, as suggested in previous works (Miranda et al., J. Magn. Magn. Mater. 185 (1998) 331; da Silva et al., IEEE Trans. Mag., to appear)

  12. Anneal-induced transformations in the transport and magnetic properties of CoCu granulars

    International Nuclear Information System (INIS)

    Miranda, M.G.M.; Antunes, A.B.; Bracho Rodriguez, G.J.; Baibich, M.N.

    2001-01-01

    The electrical and magnetic properties of granular Co 5 Cu 95 , Co 10 Cu 90 and Co 15 Cu 85 ribbons treated with different annealing procedures were measured from helium to room temperatures. The isochronous anneals had fixed heating rate and the transformations were followed by 'in situ' resistivity measurements. We found that the transformation occurs at nearly the same region of temperature for the three compositions. Besides, our results for magnetoresistance on Co 10 Cu 90 could be understood in the light of the re-dissolution of Co into the Cu matrix, as suggested in previous works (Miranda et al., J. Magn. Magn. Mater. 185 (1998) 331; da Silva et al., IEEE Trans. Mag., to appear)

  13. Laser- and gamma-induced transformations of optical spectra of indium-doped sodium borate glass

    CERN Document Server

    Kopyshinsky, O V; Zelensky, S E; Danilchenko, B A; Shakhov, O P

    2003-01-01

    The optical absorption and luminescence properties of indium-doped sodium borate glass irradiated by gamma-rays and by powerful UV lasers within the impurity-related absorption band are investigated experimentally. It is demonstrated that both the laser- and gamma-irradiation cause similar transformations of optical spectra in the UV and visible regions. The changes of the spectra observed are described with the use of a model which includes three types of impurity centres formed by differently charged indium ions.

  14. Acoustic recognition of stress induced martensitic transformations in Cu-based shape memory alloys

    Czech Academy of Sciences Publication Activity Database

    Novák, Václav; Landa, Michal; Šittner, Petr

    2003-01-01

    Roč. 112, - (2003), s. 593-596 ISSN 1155-4339 R&D Projects: GA AV ČR IAA1048107; GA ČR GA106/01/0396 Institutional research plan: CEZ:AV0Z1010914 Keywords : shape memory alloys(SMA) * Cu-based SMA * Martensitic phase transformation * acoustic emission Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.319, year: 2003

  15. Structural transformations in austenitic stainless steel induced by deuterium implantation: irradiation at 100 K.

    Science.gov (United States)

    Morozov, Oleksandr; Zhurba, Volodymyr; Neklyudov, Ivan; Mats, Oleksandr; Rud, Aleksandr; Chernyak, Nikolay; Progolaieva, Viktoria

    2015-01-01

    Deuterium thermal desorption spectra were investigated on the samples of austenitic stainless steel 18Cr10NiTi preimplanted at 100 K with deuterium ions in the dose range from 3 × 10(15) to 5 × 10(18) D/cm(2). The kinetics of structural transformation development in the implantation steel layer was traced from deuterium thermodesorption spectra as a function of implanted deuterium concentration. At saturation of austenitic stainless steel 18Cr10NiTi with deuterium by means of ion implantation, structural-phase changes take place, depending on the dose of implanted deuterium. The maximum attainable concentration of deuterium in steel is C = 1 (at.D/at.met. = 1/1). The increase in the implanted dose of deuterium is accompanied by the increase in the retained deuterium content, and as soon as the deuterium concentration attains C ≈ 0.5 the process of shear martensitic structural transformation in steel takes place. It includes the formation of bands, body-centered cubic (bcc) crystal structure, and the ferromagnetic phase. Upon reaching the deuterium concentration C > 0.5, the presence of these molecules causes shear martensitic structural transformations in the steel, which include the formation of characteristic bands, bcc crystal structure, and the ferromagnetic phase. At C ≥ 0.5, two hydride phases are formed in the steel, the decay temperatures of which are 240 and 275 K. The hydride phases are formed in the bcc structure resulting from the martensitic structural transformation in steel.

  16. Modulating effects of the protease inhibitor Antipain on x-ray induced transformations

    International Nuclear Information System (INIS)

    Borek, C.; Miller, R.C.

    1979-01-01

    Protease inhibitors have been shown to inhibit the expression of mutations in bacteria and to inhibit the tumor-promoting effect of phorbol esters in mice. We have investigated the effect of the protease inhibitor Antipain on cell transformation by x-irradiation in two in vitro systems; namely short-term cultures of freshly explanted hamster embryo cells and in the 10T1/2 cell line derived and cloned from C3H mouse embryo

  17. Possible error-prone repair of neoplastic transformation induced by fission-spectrum neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Hill, C K; Han, A; Elkind, M M

    1948-01-01

    An examination was made of the effect of fission-spectrum neutrons from the JANUS reactor at Argonne National Laboratory, delivered either as acute or protracted irradiation, on the incidence of neoplastic transformation in the C3H 10T1/2 mouse embryo cell line. Acute exposures were delivered at 10-38 cGy min/sup -1/, protracted exposures at 0.086 or 0.43 cGy min/sup -1/. The total doses for both ranged from 2.4 to 350 cGy. In the low dose region (2.4-80 cGy), there was a large enhancement in transformation frequency when the neutrons were delivered at the low dose rates compared with the high dose rates, but the survival of the cells was not significantly different between the two exposures conditions. Analysis of the intial parts of the curves shows that the regression line for protracted doses is about 9 times steeper than that for single acute exposures. Finally, the possibility is discussed that an ''error-prone'' repair process may be causing the enhanced transformation frequency by protracted neutron exposures.

  18. In vitro cellular transformation induced by charged particles of defined LET

    International Nuclear Information System (INIS)

    Hei, T.K.; Hall, E.J.; Komatsu, K.; Goldhagen, P.

    1985-01-01

    Cytotoxicity and neoplastic transformation were scored in the C/sub 3/H 10T1/2 cell system following irradiation with protons, deuterons and helium-3 ions of defined LET in the track segment mode. The charged particles were accelerated at the Radiological Research Accelerator Facility at the Nevis Laboratories of Columbia University and provided a range of LET values from 10 to 175 keV/μm. Exponential phase cultures of C3H 10T1/2 cells, growing on a thin mylar surface were irradiated with charged particles of various LET values and subsequently replated onto commercial plastic petri dishes. The cultures were incubated for six weeks at which time they were fixed, stained and type II and III scored as transformants. Over the range of LET values studied thus far, it was found that as the LET of the charged particles increased, the shoulder of the survival curves decreased and approached an exponential function of dose at LET values of 100 keV/μm and above. The transformation incidence, likewise, showed a direct correlation with LET over the dose ranges examined

  19. Fracture toughness for materials of low ductility

    International Nuclear Information System (INIS)

    Barzilay, S.; Karp, B.; Perl, M.

    1998-05-01

    The results of a survey of methods for evaluating fracture toughness characteristics for semi-brittle and brittle materials are presented in this report. These methods differ considerably from those used for ductile materials by the specimen configurations, the methodology of the experiments and by the problems occurring while using these methods. The survey yields several important findings A. It is possible to create steady state crack growth by cyclic loading in several semi-brittle materials. B. The need for pre-cracking is not yet clear, nevertheless it is recommended to evaluate fracture toughens with pre-cracked specimen. C. As crack length and ligament size may effect fracture toughness results it is necessary to define minimum specimen dimensions to avoid this effect. D. The specimen thickness hardly affects the fracture toughens. E. Loading rate for the test is not well defined. It is commonly accepted to end the test in one minute. F. The main mechanism that causes inelastic deformation in semi-brittle materials is related to the generation of micro-cracks

  20. The crystallography of carbide-free bainites in thermo-mechanically processed low Si transformation-induced plasticity steels

    Energy Technology Data Exchange (ETDEWEB)

    Pereloma, Elena V. [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, New South Wales 2522 (Australia); Electron Microscopy Centre, University of Wollongong, New South Wales 2500 (Australia); Al-Harbi, Fayez [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, New South Wales 2522 (Australia); Gazder, Azdiar A., E-mail: azdiar@uow.edu.au [Electron Microscopy Centre, University of Wollongong, New South Wales 2500 (Australia)

    2014-12-05

    Highlights: • First EBSD study comparing ferrite in granular bainite and bainitic laths in two TRIP steels. • Both TRIP steels (base and with Nb–Ti additions) subjected to the same TMP schedule. • Crystallography of the ferrite in the 2 bainites studied using the K–S orientation relationship. • Variants in GB associated with self-accommodation. • BF variant selection linked to RA plastic accommodation and limited volume. - Abstract: Carbide-free bainites are important microstructural constituents in bainitic, nanobainitic and transformation-induced plasticity (TRIP) steels. A comparison of the crystallography of ferrite in granular bainite and bainitic ferrite lath morphologies, both of which were simultaneously present in a base and a Nb–Ti containing TRIP steel, has been carried out using electron back-scattering diffraction. Ferrite in granular bainite was characterised by the realisation of nearly all 24 variants of the Kurdjumov–Sachs orientation relationship; which in turn was associated with the self-accommodation of the transformation strain. On the other hand, bainitic ferrite comprised a mostly parallel lath structure between thick interlayers of retained austenite and exhibited variant selection such that one or more crystallographic packets are not realised and sometimes only 1–2 variants formed in a crystallographic packet. The variant selection in bainitic ferrite laths was associated with: (i) the plastic accommodation of transformation strain by retained austenite and, (ii) the limited available volume for its formation.

  1. Magnetic-field-induced martensitic transformation of off-stoichiometric single-crystal Ni2MnGa

    International Nuclear Information System (INIS)

    Inoue, Kazuko; Yamaguchi, Yasuo; Shishido, Toetsu; Ishii, Yoshinobu; Yamauchi, Hiroki

    2009-01-01

    The effect of a magnetic field on the martensitic transformation of an off-stoichiometric Heusler type Ni 2.16 Mn 0.78 Ga 1.06 single crystal has been revealed by neutron diffraction. The alloy undergoes a martensitic transformation at room temperature, which is nearly coincident with its Curie temperature. Splitting of the cubic (020) peak on the reciprocal lattice cubic c * -plane was traced at 293 K by a triple-axis neutron spectrometer under an increasing magnetic field of up to 10 T. It was found that the magnetic field causes the martensitic transformation from the cubic structure to the orthorhombic structure, which is the same as that caused by decreasing the temperature without a magnetic field. The increase in the magnetic field to 10 T appears to correspond to a decrease in temperature of nearly 12 K, i.e., from 293 to 281 K. The present experiment suggests the possibility of realizing a magnetic-field-induced shape memory alloy. (author)

  2. The crystallography of carbide-free bainites in thermo-mechanically processed low Si transformation-induced plasticity steels

    International Nuclear Information System (INIS)

    Pereloma, Elena V.; Al-Harbi, Fayez; Gazder, Azdiar A.

    2014-01-01

    Highlights: • First EBSD study comparing ferrite in granular bainite and bainitic laths in two TRIP steels. • Both TRIP steels (base and with Nb–Ti additions) subjected to the same TMP schedule. • Crystallography of the ferrite in the 2 bainites studied using the K–S orientation relationship. • Variants in GB associated with self-accommodation. • BF variant selection linked to RA plastic accommodation and limited volume. - Abstract: Carbide-free bainites are important microstructural constituents in bainitic, nanobainitic and transformation-induced plasticity (TRIP) steels. A comparison of the crystallography of ferrite in granular bainite and bainitic ferrite lath morphologies, both of which were simultaneously present in a base and a Nb–Ti containing TRIP steel, has been carried out using electron back-scattering diffraction. Ferrite in granular bainite was characterised by the realisation of nearly all 24 variants of the Kurdjumov–Sachs orientation relationship; which in turn was associated with the self-accommodation of the transformation strain. On the other hand, bainitic ferrite comprised a mostly parallel lath structure between thick interlayers of retained austenite and exhibited variant selection such that one or more crystallographic packets are not realised and sometimes only 1–2 variants formed in a crystallographic packet. The variant selection in bainitic ferrite laths was associated with: (i) the plastic accommodation of transformation strain by retained austenite and, (ii) the limited available volume for its formation

  3. Ductile fracture behavior of cast structure containing voids

    International Nuclear Information System (INIS)

    Gilles, Ph.; Migne, C.; Chapuliot, S.

    2001-01-01

    In pressurized water reactors, the primary loop contains cast-piping components made of duplex stainless steel. Due to the presence of ferrite, such steels are susceptible to thermal aging embrittlement, which decrease their fracture resistance. The cast process induces shrinkage cavities, therefore all these components are submitted to liquid penetrant examination and all surface defects are repaired. EDF, CEA and Framatome have conducted experimental and analytical analysis of fatigue and fracture behavior of aged cast stainless steel structures containing shrinkage cavities. The present study considers only ductile tearing and is based on specimen test results and a fracture mechanics model of the interaction between shrinkage cavities. The experimental results presented here show that large groups of shrinkage cavities have almost no influence on the global behavior of the structure. Only for the specimen with the largest reduction of area, a significant reduction of strength has been registered. Using elementary fracture mechanics models, it has been evidenced that failure mechanism of structures containing shrinkage cavities consists in 3 phases: local initiation, macro-crack formation by coalescence and failure by crack instability or collapse depending if J resistance is low or not. No significant changes in global behavior appear in the first phase. (A.C.)

  4. Ductile fracture behavior of cast structure containing voids

    Energy Technology Data Exchange (ETDEWEB)

    Gilles, Ph.; Migne, C. [FRAMATOME ANP, 92 - Paris-La-Defence (France); Chapuliot, S. [CEA Saclay, 91 - Gif-sur-Yvette (France). Dept. de Mecanique et de Technologie

    2001-07-01

    In pressurized water reactors, the primary loop contains cast-piping components made of duplex stainless steel. Due to the presence of ferrite, such steels are susceptible to thermal aging embrittlement, which decrease their fracture resistance. The cast process induces shrinkage cavities, therefore all these components are submitted to liquid penetrant examination and all surface defects are repaired. EDF, CEA and Framatome have conducted experimental and analytical analysis of fatigue and fracture behavior of aged cast stainless steel structures containing shrinkage cavities. The present study considers only ductile tearing and is based on specimen test results and a fracture mechanics model of the interaction between shrinkage cavities. The experimental results presented here show that large groups of shrinkage cavities have almost no influence on the global behavior of the structure. Only for the specimen with the largest reduction of area, a significant reduction of strength has been registered. Using elementary fracture mechanics models, it has been evidenced that failure mechanism of structures containing shrinkage cavities consists in 3 phases: local initiation, macro-crack formation by coalescence and failure by crack instability or collapse depending if J resistance is low or not. No significant changes in global behavior appear in the first phase. (A.C.)

  5. Thermomechanical Fatigue of Ductile Cast Iron and Its Life Prediction

    Science.gov (United States)

    Wu, Xijia; Quan, Guangchun; MacNeil, Ryan; Zhang, Zhong; Liu, Xiaoyang; Sloss, Clayton

    2015-06-01

    Thermomechanical fatigue (TMF) behaviors of ductile cast iron (DCI) were investigated under out-of-phase (OP), in-phase (IP), and constrained strain-control conditions with temperature hold in various temperature ranges: 573 K to 1073 K, 723 K to 1073 K, and 433 K to 873 K (300 °C to 800 °C, 450 °C to 800 °C, and 160 °C to 600 °C). The integrated creep-fatigue theory (ICFT) model was incorporated into the finite element method to simulate the hysteresis behavior and predict the TMF life of DCI under those test conditions. With the consideration of four deformation/damage mechanisms: (i) plasticity-induced fatigue, (ii) intergranular embrittlement, (iii) creep, and (iv) oxidation, as revealed from the previous study on low cycle fatigue of the material, the model delineates the contributions of these physical mechanisms in the asymmetrical hysteresis behavior and the damage accumulation process leading to final TMF failure. This study shows that the ICFT model can simulate the stress-strain response and life of DCI under complex TMF loading profiles (OP and IP, and constrained with temperature hold).

  6. Aspirin induces morphological transformation to the secretory state in isolated rabbit parietal cells.

    Science.gov (United States)

    Murthy, U K; Levine, R A

    1991-08-01

    The morphological response of rabbit parietal cells to aspirin was evaluated by grading several ultra-structural features including the extent of the tubulovesicular system, intracellular secretory canaliculi, and microvilli. After exposure of isolated parietal cells and gastric glands to aspirin or histamine, there was an approximately twofold increase in the ratio of secretory to nonsecretory parietal cells, and depletion of extracellular Ca2+ abolished the aspirin-induced morphological changes. Morphometry in parietal cells showed that aspirin induced a sixfold increase in secretory canalicular membrane elaboration. Aspirin potentiated histamine-induced parietal cell respiration and aminopyrine uptake ratio but did not increase basal respiration or aminopyrine uptake, suggesting an apparent dissociation from aspirin-induced morphological changes.

  7. Ductile alloy and process for preparing composite superconducting wire

    Science.gov (United States)

    Verhoeven, J.D.; Finnemore, D.K.; Gibson, E.D.; Ostenson, J.E.

    An alloy for the commercial production of ductile superconducting wire is prepared by melting together copper and at least 15 weight percent niobium under non-oxygen-contaminating conditions, and rapidly cooling the melt to form a ductile composite consisting of discrete, randomly distributed and oriented dendritic-shaped particles of niobium in a copper matrix. As the wire is worked, the dendritic particles are realigned parallel to the longitudinal axis and when drawn form a plurality of very fine ductile superconductors in a ductile copper matrix. The drawn wire may be tin coated and wound into magnets or the like before diffusing the tin into the wire to react with the niobium. Impurities such as aluminum or gallium may be added to improve upper critical field characteristics.

  8. Ductility in hot isostatically pressed 250-grade maraging steel

    International Nuclear Information System (INIS)

    German, R.M.; Smugeresky, J.E.

    1978-01-01

    Prealloyed 250-grade maraging steel powder produced by the rotating electrode process was fully consolidated by hot isostatic pressing (HIP) at 1100 and 1200 0 C. The strength following aging (3 h at 480 0 C) equalled that of wrought material; however, ductility was negligible. This lack of ductility in the powder metallurgy product was traced to titanium segregation which occurred at the powder surface during power production. The formation of a titanium intermetallic at the prior particle boundaries during aging caused failure at low plastic strains. Altered aging treatments successfully broke up the embrittling film and resulted in a significant ductility recovery for the HIP material. Analysis of the fracture process indicates that further ductility gains are possible by reducing the titanium content, refining the particle size, and optimizing the thermal cycles

  9. High temperature ductility of austenitic alloys exposed to thermal neutrons

    International Nuclear Information System (INIS)

    Watanabe, K.; Kondo, T.; Ogawa, Y.

    1982-01-01

    Loss of high temperature ductility due to thermal neutron irradiation was examined by slow strain rate test in vacuum up to 1000 0 C. The results on two heats of Hastelloy alloy X with different boron contents were analyzed with respect to the influence of the temperatures of irradiation and tensile tests, neutron fluence and the associated helium production due to nuclear transmutation reaction. The loss of ductility was enhanced by increasing either temperature or neutron fluence. Simple extrapolations yielded the estimated threshold fluence and the end-of-life ductility values at 900 and 1000 0 C in case where the materials were used in near-core regions of VHTR. The observed relationship between Ni content and the ductility loss has suggested a potential utilization of Fe-based alloys for seathing of the neutron absorber materials

  10. Ductility loss of ion-irradiated zircaloy-2 in iodine

    International Nuclear Information System (INIS)

    Shimada, M.; Terasawa, M.; Yamamoto, S.; Kamei, H.; Koizumi, K.

    1981-01-01

    An ion bombardment simulation technique for neutron irradiation was applied to 'thick' materials to study the effect of radiation damage on the ductility change in Zircaloy-2 in an iodine environment. Specimens were prepared from actual cladding tubes and, prior to the irradiation, they were heat-treated in vacuo at 450, 580, and 700/degree/C for 2 h. Irradiation was performed by 52-MeV alpha particles up to the 0.32 displacements per atom (dpa) at 340/degree/C. Ductility loss begins to appear after 0.03 dpa irradiation, both in iodine and argon gas environments. The iodine presence resulted in ductility reduction, compared with the argon result in all irradiation dose ranges examined. The stress applied during irradiation caused ductility loss to commence at lower dosage than in the case of stress-free irradiation. These results are discussed in relation to the existing stress corrosion cracking models

  11. Initial stages of ion beam-induced phase transformations in Gd2O3 and Lu2O3

    Science.gov (United States)

    Chen, Chien-Hung; Tracy, Cameron L.; Wang, Chenxu; Lang, Maik; Ewing, Rodney C.

    2018-02-01

    The atomic-scale evolution of lanthanide sesquioxides Gd2O3 and Lu2O3 irradiated with 1 MeV Kr ions at room temperature and 120 K, up to fluences of 1 × 1016 ions/cm2 (˜20 dpa), has been characterized by in situ transmission electron microscopy. At room temperature, both oxides exhibited high radiation tolerance. Irradiation did not cause any observable structural change in either material, likely due to the mobility of irradiation-induced point defects, causing efficient defect annihilation. For Gd2O3, having the larger cation ionic radius of the two materials, an irradiation-induced stacking fault structure appeared at low fluences in the low temperature irradiation. As compared with the cubic-to-monoclinic phase transformations known to result from higher energy (˜GeV) ion irradiation, Kr ions of lower energies (˜MeV) yield much lower rates of damage accumulation and thus less extensive structural modification. At a fluence of 2.5 × 1015 ions/cm2, only the initial stages of the cubic-to-monoclinic (C to B) phase transformation process, consisting of the formation and aggregation of defects, have been observed.

  12. Loss of cellular transformation efficiency induced by DNA irradiation with low-energy (10 eV) electrons.

    Science.gov (United States)

    Kouass Sahbani, Saloua; Sanche, Leon; Cloutier, Pierre; Bass, Andrew D; Hunting, Darel J

    2014-11-20

    Low energy electrons (LEEs) of energies less than 20 eV are generated in large quantities by ionizing radiation in biological matter. While LEEs are known to induce single (SSBs) and double strand breaks (DSBs) in DNA, their ability to inactivate cells by inducing nonreparable lethal damage has not yet been demonstrated. Here we observe the effect of LEEs on the functionality of DNA, by measuring the efficiency of transforming Escherichia coli with a [pGEM-3Zf (-)] plasmid irradiated with 10 eV electrons. Highly ordered DNA films were prepared on pyrolitic graphite by molecular self-assembly using 1,3-diaminopropane ions (Dap(2+)). The uniformity of these films permits the inactivation of approximately 50% of the plasmids compared to transforming cluster damage into DSBs by digestion with repair enzymes, also occurred relatively infrequently. The exact nature of the lethal damage remains unknown, but it is probably a form of compact cluster damage in which the lesions are too close to be revealed by purified repair enzymes. In addition, this damage is either not repaired or is misrepaired by E. coli, since it results in plasmid inactivation, when they contain an average of three lesions. Comparison with previous results from a similar experiment performed with γ-irradiated plasmids indicates that the type of clustered DNA lesions, created directly on cellular DNA by LEEs, may be more difficult to repair than those produced by other species from radiolysis.

  13. Effects of tryptophan derivatives and β-carboline alkaloids on radiation- and peroxide-induced transformations of ethanol

    International Nuclear Information System (INIS)

    Sverdlov, R.L.; Brinkevich, S.D.; Shadyro, O.I.

    2014-01-01

    The subject of this study was investigation of interactions of tryptophan and its derivatives, including structurally related β-carboline alkaloids with oxygen- and carbon-centered radicals being formed during radiation- and peroxide-induced transformations of ethanol. It was shown that the above named compounds suppressed recombination and disproportionation reactions of α-hydroxyethyl radicals. The inhibitory effects of tryptophan, 5-hydroxytryptophan and serotonin were mainly realized by means of reduction and addition reactions, while those of β-carboline alkaloids – harmine, harmane and harmaline – were due to oxidation reactions. Melatonin displayed low reactivity towards α-hydroxyethyl radicals. Tryptophan derivatives and β-carboline alkaloids were found to inhibit radiation-induced oxidation of ethanol while being virtually not used up. The low transformation yields of tryptophan, 5-hydroxytryptophan and serotonin, as well as β-carboline alkaloids, indicate their capability of regeneration, which could occur on interaction of tryptophan with O ·− 2 and HO · 2 , or on oxidation of α-hydroxyethyl radicals by β-carboline alkaloids. - Highlights: • Tryptophan, 5-hydroxytryptophane and serotonin can reduce or add α-HER. • β-Carboline alkaloids – harmane, harmine, harmaline – can oxidize α-HER. • Tryptophan and its derivatives can reduce oxygen-centered radicals

  14. Formation of Shc-Grb2 complexes is necessary to induce neoplastic transformation by overexpression of Shc proteins

    DEFF Research Database (Denmark)

    Salcini, A E; McGlade, J; Pelicci, G

    1994-01-01

    The mammalian SHC gene encodes three overlapping proteins which all contain a carboxy-terminal SH2 domain. Shc proteins are phosphorylated on tyrosine by a variety of receptor and cytoplasmic tyrosine kinases. Phosphorylated Shc proteins form a complex with the SH2-SH3 containing Grb2 protein which...... of Grb2 to Shc proteins requires phosphorylation of Shc at Tyr317, which lies within the high affinity binding motif for the Grb2 SH2 domain, pYVNV, where Asn at the +2 position is crucial for complex formation. In vivo, Tyr317 is the major, but not the only, site for Shc phosphorylation, and is the sole...... aminoterminal deletion, but retain the Tyr317 site and the SH2 domain conserve the capacity to be phosphorylated, to bind to Grb2 and to induce cell transformation. These data indicate that the formation of the Shc-Grb2 complex is a crucial event in the transformation induced by overexpression of Shc...

  15. Electrochemically induced transformation of NiS nanoparticles into Ni(OH)2 in KOH aqueous solution toward electrochemical capacitors

    International Nuclear Information System (INIS)

    Hou Linrui; Yuan Changzhou; Li Diankai; Yang Long; Shen Laifa; Zhang Fang; Zhang Xiaogang

    2011-01-01

    Highlights: → NiS is synthesized by means of the H 2 O/CS 2 interface under hydrothermal treatment. → NiS itself owns poor electrochemical capacitance in 2 M KOH solution. → NiS is electrochemically induced and transformed into electroactive Ni(OH) 2 . → Ni(OH) 2 is responsible for good energy storage of the NiS in the KOH solution. → The new formed Ni(OH) 2 delivers large energy density at high rates. - Abstract: Nickel sulfide nanoparticles (NPs) are first synthesized by virtue of a unique H 2 O/CS 2 interface under mild hydrothermal treatment. Electrochemical data reveals that the as-synthesized NiS NPs themselves own poor supercapacitive behavior at initial cyclic voltammetry (CV) cycles in 2 M KOH solution, while a specific capacitance of 893 F g -1 can be surprisingly obtained at a current density of 5 A g -1 just after continuous 320 CV cycles. X-ray diffraction and Fourier transform infrared techniques demonstrate that what is really responsible for the good electrochemical capacitance in the KOH aqueous solution is the new electrochemically formed Ni(OH) 2 phase, rather than NiS NPs themselves. The Ni(OH) 2 is slowly formed during the continuous CV cycling process, in which the electrochemically induced phase transformation from NiS to Ni(OH) 2 phase takes place. Furthermore, the new Ni(OH) 2 phase demonstrates the great ability of delivering large specific capacitance at high rates.

  16. Mechanistic origin and prediction of enhanced ductility in magnesium alloys

    Science.gov (United States)

    Wu, Zhaoxuan; Ahmad, Rasool; Yin, Binglun; Sandlöbes, Stefanie; Curtin, W. A.

    2018-01-01

    Development of ductile magnesium alloys is key to their use in reducing the weight of vehicles and other applications. Wu et al. tackle this issue by determining the underlying mechanisms in unprocessed magnesium alloys. Dilute amounts of solutes enhanced certain ductility-improving mechanisms over ones that cause brittle fracture. From this, the authors developed a theory that may be helpful for screening the large number of potential magnesium alloy compositions.

  17. Study of austempering reaction in austempered ductile iron

    International Nuclear Information System (INIS)

    Ja'far Farhan Al-Sharab; Sharma, D.G.R.; Samsul Bahar Sadli

    1996-01-01

    Austempered Ductile Iron (ADI) is an important engineering material which is gaining popularity. The conventional belief that austempered ductile iron, when heat treated satisfactorily, contains bainite, is now disproved by recent experiments. Our present work on the study of the reaction products of heat treated ADI by x-ray diffraction confirms the recent view. The results of x-ray diffraction studies on the structural constituents od ADI for various durations of austempering are presented and discussed

  18. 49 CFR 192.373 - Service lines: Cast iron and ductile iron.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Service lines: Cast iron and ductile iron. 192.373... Regulators, and Service Lines § 192.373 Service lines: Cast iron and ductile iron. (a) Cast or ductile iron... cast iron pipe or ductile iron pipe is installed for use as a service line, the part of the service...

  19. Electrochemically induced dual reactive barriers for transformation of TCE and mixture of contaminants in groundwater.

    Science.gov (United States)

    Mao, Xuhui; Yuan, Songhu; Fallahpour, Noushin; Ciblak, Ali; Howard, Joniqua; Padilla, Ingrid; Loch-Caruso, Rita; Alshawabkeh, Akram N

    2012-11-06

    A novel reactive electrochemical flow system consisting of an iron anode and a porous cathode is proposed for the remediation of mixture of contaminants in groundwater. The system consists of a series of sequentially arranged electrodes, a perforated iron anode, a porous copper cathode followed by a mesh-type mixed metal oxide anode. The iron anode generates ferrous species and a chemically reducing environment, the porous cathode provides a reactive electrochemically reducing barrier, and the inert anode provides protons and oxygen to neutralize the system. The redox conditions of the electrolyte flowing through this system can be regulated by controlling the distribution of the electric current. Column experiments are conducted to evaluate the process and study the variables. The electrochemical reduction on a copper foam cathode produced an electrode-based reductive potential capable of reducing TCE and nitrate. Rational electrodes arrangement, longer residence time of electrolytes and higher surface area of the foam electrode improve the reductive transformation of TCE. More than 82.2% TCE removal efficiency is achieved for the case of low influent concentration (45 mA). The ferrous species produced from the iron anode not only enhance the transformation of TCE on the cathode, but also facilitates transformation of other contaminants including dichromate, selenate and arsenite. Removal efficiencies greater than 80% are achieved for these contaminants in flowing contaminated water. The overall system, comprising the electrode-based and electrolyte-based barriers, can be engineered as a versatile and integrated remedial method for a relatively wide spectrum of contaminants and their mixtures.

  20. DC heating induced shape transformation of Ge structures on ultraclean Si(5 5 12) surfaces.

    Science.gov (United States)

    Dash, J K; Rath, A; Juluri, R R; Raman, P Santhana; Müller, K; Rosenauer, A; Satyam, P V

    2011-04-06

    We report the growth of Ge nanostructures and microstructures on ultraclean, high vicinal angle silicon surfaces and show that self-assembled growth at optimum thickness of the overlayer leads to interesting shape transformations, namely from nanoparticle to trapezoidal structures, at higher thickness values. Thin films of Ge of varying thickness from 3 to 12 ML were grown under ultrahigh vacuum conditions on a Si(5 5 12) substrate while keeping the substrate at a temperature of 600 °C. The substrate heating was achieved by two methods: (i) by heating a filament under the substrate (radiative heating, RH) and (ii) by passing direct current through the samples in three directions (perpendicular, parallel and at 45° to the (110) direction of the substrate). We find irregular, more spherical-like island structures under RH conditions. The shape transformations have been found under DC heating conditions and for Ge deposition more than 8 ML thick. The longer sides of the trapezoid structures are found to be along (110) irrespective of the DC current direction. We also show the absence of such a shape transformation in the case of Ge deposition on Si(111) substrates. Scanning transmission electron microscopy measurements suggested the mixing of Ge and Si. This has been confirmed with a quantitative estimation of the intermixing using Rutherford backscattering spectrometry (RBS) measurements. The role of DC heating in the formation of aligned structures is discussed. Although the RBS simulations show the presence of a possible SiO(x) layer, under the experimental conditions of the present study, the oxide layer would not play a role in determining the formation of the various structures that were reported here.

  1. Graphene as a nanocarrier for tamoxifen induces apoptosis in transformed cancer cell lines of different origins.

    Science.gov (United States)

    Misra, Santosh K; Kondaiah, Paturu; Bhattacharya, Santanu; Rao, C N R

    2012-01-09

    A cationic amphiphile, cholest-5en-3β-oxyethyl pyridinium bromide (PY(+) -Chol), is able to efficiently disperse exfoliated graphene (GR) in water by the physical adsorption of PY(+) -Chol on the surface of GR to form stable, dark aqueous suspensions at room temperature. The GR-PY(+) -Chol suspension can then be used to solubilize Tamoxifen Citrate (TmC), a breast cancer drug, in water. The resulting TmC-GR-PY(+) -Chol is stable for a long time without any precipitation. Fluorescence emission and UV absorption spectra indicate the existence of noncovalent interactions between TmC, GR, and PY(+) -Chol in these suspensions. Electron microscopy shows the existence of segregated GR sheets and TmC 'ribbons' in the composite suspensions. Atomic force microscopy indicates the presence of 'extended' structures of GR-PY(+) -Chol, which grows wider in the presence of TmC. The slow time-dependent release of TmC is noticed in a reconstituted cell culture medium, a property useful as a drug carrier. TmC-GR-PY(+) -Chol selectively enhanced the cell death (apoptosis) of the transformed cancer cells compared to normal cells. This potency is found to be true for a wide range of transformed cancer cells viz. HeLa, A549, ras oncogene-transformed NIH3T3, HepG2, MDA-MB231, MCF-7, and HEK293T compared to the normal cell HEK293 in vitro. Confocal microscopy confirmed the high efficiency of TmC-GR-PY(+) -Chol in delivering the drug to the cells, compared to the suspensions devoid of GR. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Prox1-Heterozygosis Sensitizes the Pancreas to Oncogenic Kras-Induced Neoplastic Transformation

    Directory of Open Access Journals (Sweden)

    Yiannis Drosos

    2016-03-01

    Full Text Available The current paradigm of pancreatic neoplastic transformation proposes an initial step whereby acinar cells convert into acinar-to-ductal metaplasias, followed by progression of these lesions into neoplasias under sustained oncogenic activity and inflammation. Understanding the molecular mechanisms driving these processes is crucial to the early diagnostic and prevention of pancreatic cancer. Emerging evidence indicates that transcription factors that control exocrine pancreatic development could have either, protective or facilitating roles in the formation of preneoplasias and neoplasias in the pancreas. We previously identified that the homeodomain transcription factor Prox1 is a novel regulator of mouse exocrine pancreas development. Here we investigated whether Prox1 function participates in early neoplastic transformation using in vivo, in vitro and in silico approaches. We found that Prox1 expression is transiently re-activated in acinar cells undergoing dedifferentiation and acinar-to-ductal metaplastic conversion. In contrast, Prox1 expression is largely absent in neoplasias and tumors in the pancreas of mice and humans. We also uncovered that Prox1-heterozygosis markedly increases the formation of acinar-to-ductal-metaplasias and early neoplasias, and enhances features associated with inflammation, in mouse pancreatic tissues expressing oncogenic Kras. Furthermore, we discovered that Prox1-heterozygosis increases tissue damage and delays recovery from inflammation in pancreata of mice injected with caerulein. These results are the first demonstration that Prox1 activity protects pancreatic cells from acute tissue damage and early neoplastic transformation. Additional data in our study indicate that this novel role of Prox1 involves suppression of pathways associated with inflammatory responses and cell invasiveness.

  3. Influence of phosphorus on the creep ductility of copper

    International Nuclear Information System (INIS)

    Sandström, Rolf; Wu, Rui

    2013-01-01

    Around 1990 it was discovered that pure copper could have extra low creep ductility in the temperature interval 180–250 °C. The material was intended for use in canisters for nuclear waste disposal. Although extra low creep ductility was not observed much below 180 °C and the temperature in the canister will never exceed 100 °C, it was feared that the creep ductility could reach low values at lower temperatures after long term exposure. If 50 ppm phosphorus was added to the copper the low creep ductility disappeared. A creep cavitation model is presented that can quantitatively describe the cavitation behaviour in uniaxial and multiaxial creep tests as well as the observed creep ductility for copper with and without phosphorus. A so-called double ledge model has been introduced that demonstrates why the nucleation rate of creep cavities is often proportional to the creep rate. The phosphorus agglomerates at the grain boundaries and limits their local deformation and thereby reduces the formation and growth of cavities. This explains why extra low creep ductility does not occur in phosphorus alloyed copper

  4. Ductility of Ni3Al doped with substitutional elements

    International Nuclear Information System (INIS)

    Hanada, S.; Chiba, A.; Guo, H.Z.; Watanabe, S.

    1993-01-01

    This paper reports on ductility of B-free Ni 3 Al alloys. Recrystallized Ni 3 Al binary alloys with Ni-rich compositions show appreciable ductility when an environmental effect is eliminated, while the alloys with stoichiometric and Al-rich compositions remain brittle. The ductility in the Ni-rich Ni 3 Al alloys is associated with low ordering energy. The additions of ternary elements, which are classified as γ formers, ductilize ternary Ni 3 Al alloys(Ni-23 at% Al-2 at% X, X = Pd, Pt, Cu and Co), whereas the additions of γ' formers embrittle ternary Ni 3 Al alloys(Ni-23 at% Al-2 at% X, X = Ta, Mo, Nb, Zr, Hf, V, Ti and Si). The additions of small amounts (less than 1 at%) of γ' formers such as Zr and Hf also ductilize as-cast ternary Ni 3 Al alloys. Ductility of Ni 3 Al alloys doped with substitutional elements is discussed in terms of ordering energy and microstructure

  5. Simulation of the ductile damage under the metal forming

    International Nuclear Information System (INIS)

    Bogatov, A. A.

    2003-01-01

    Potentiality of metal forming is limited by ductile damage. The damage degree is estimated by the scalar value ω, that is equal to 0(ω=0) before plastic strain and is equal to 1(ω=1) at the macro cracks moment. There are two criteria that describe micro damage. The value ω=ω * corresponds to the generation of micro voids that couldn't be recovered by recrystallization but do not reduce the metal strength. The value ω=ω ** corresponds to the generation of micro voids that reduce the metal strength and material long life. The models of metal damage accumulation under pure and alternate strain also the model of metal damage recovery under the recrystallization are developed. The specimen testing at high loading parameters gives the basic equations of the ductile damage mechanics. All of that gives the method to study ductile damage under the metal forming. The methodology damage nucleation and growing is shown on various examples: the void and crack development in the areas ductile damage and unlimited ductility; mathematical simulation of the metal damage under the sheet and wire drawing and others. The problems of physical simulating at the ductile damage under metal forming are shown too in this paper. The method and equipment of metal damage physical simulation are proposed. (Original)

  6. Athermal brittle-to-ductile transition in amorphous solids.

    Science.gov (United States)

    Dauchot, Olivier; Karmakar, Smarajit; Procaccia, Itamar; Zylberg, Jacques

    2011-10-01

    Brittle materials exhibit sharp dynamical fractures when meeting Griffith's criterion, whereas ductile materials blunt a sharp crack by plastic responses. Upon continuous pulling, ductile materials exhibit a necking instability that is dominated by a plastic flow. Usually one discusses the brittle to ductile transition as a function of increasing temperature. We introduce an athermal brittle to ductile transition as a function of the cutoff length of the interparticle potential. On the basis of extensive numerical simulations of the response to pulling the material boundaries at a constant speed we offer an explanation of the onset of ductility via the increase in the density of plastic modes as a function of the potential cutoff length. Finally we can resolve an old riddle: In experiments brittle materials can be strained under grip boundary conditions and exhibit a dynamic crack when cut with a sufficiently long initial slot. Mysteriously, in molecular dynamics simulations it appeared that cracks refused to propagate dynamically under grip boundary conditions, and continuous pulling was necessary to achieve fracture. We argue that this mystery is removed when one understands the distinction between brittle and ductile athermal amorphous materials.

  7. Determination of Ductile Tearing Resistance Curve in Weld Joints

    International Nuclear Information System (INIS)

    Marie, S.; Gilles, P.; Ould, P.

    2010-01-01

    Steels present in the ductile domain a tearing resistance which increase with the crack propagation up to the failure. This ductile tearing resistance is in general characterised with curves giving the variation of a global parameter (opening displacement at the crack tip delta, integral J) versus the crack extension Delta a. These global approaches depend more or less on the specimen geometry and on the type of the imposed loading. Local approaches based on the description of the ductile tearing mechanisms provide reliable solution to the transferability problem (from the lab specimen to the component) but are complex and costly to use and are not codified. These problems get worse in the case of a weld joint where no standard is available for the measurement of their ductile tearing resistance. But the welded joints are often the weak point of the structure because of greater risk of defects, the heterogeneity of the microstructure of the weld, deformation along the interface between two materials with different yield stress (mismatch).... After briefly recalling the problems of transferability of the ductile tearing resistance curves obtained on lab specimen to the case of components, this article identifies the factors complicating the determination of the toughness in the welded joints and gives recommendations for the experimental determination of ductile tearing resistance curves of welded joints

  8. Molecular Dynamics Simulation of Nanoindentation-induced Mechanical Deformation and Phase Transformation in Monocrystalline Silicon

    Directory of Open Access Journals (Sweden)

    Jian Sheng-Rui

    2008-01-01

    Full Text Available AbstractThis work presents the molecular dynamics approach toward mechanical deformation and phase transformation mechanisms of monocrystalline Si(100 subjected to nanoindentation. We demonstrate phase distributions during loading and unloading stages of both spherical and Berkovich nanoindentations. By searching the presence of the fifth neighboring atom within a non-bonding length, Si-III and Si-XII have been successfully distinguished from Si-I. Crystallinity of this mixed-phase was further identified by radial distribution functions.

  9. Fatigue performance of superelastic NiTi near stress-induced martensitic transformation

    Czech Academy of Sciences Publication Activity Database

    Alarcón Tarquino, Eduardo; Heller, Luděk; Chirani, S.A.; Šittner, Petr; Kopeček, Jaromír; Saint-Sulpice, L.; Calloch, S.

    2017-01-01

    Roč. 95, Feb (2017), s. 76-89 ISSN 0142-1123 R&D Projects: GA ČR GB14-36566G; GA MŠk LO1409; GA MŠk LM2015088; GA ČR GA16-20264S; GA ČR GA14-15264S Grant - others:FUNBIO(XE) CZ.2.16/3.1.00/21568 Institutional support: RVO:68378271 Keywords : shape-memory alloys * Nitinol * superelasticity * martensitic transformation * shape memory alloys * fatigue Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.899, year: 2016

  10. Reversible pressure-induced crystal-amorphous structural transformation in ice Ih

    Science.gov (United States)

    English, Niall J.; Tse, John S.

    2014-08-01

    Molecular dynamics (MD) simulation of depressurised high-density amorphous ice (HDA) at 80 K and at negative pressures has been performed. Over several attempts, HDA recrystallised to a form close to hexagonal ice Ih, albeit with some defects. The results support the hypothesis that compression of ice-Ih to HDA is a reversible first-order phase transition, with a large hysteresis. Therefore, it would appear that LDA is not truly amorphous. The elastic energy estimated from the area of the hysteresis loop is ca. 4.5 kJ/mol, in some way consistent with experimentally-determined accumulated successive heats of transformations from recovered HDA → ice Ih.

  11. Effect of fully and semi austempering treatment on the fatigue properties of ductile cast iron

    International Nuclear Information System (INIS)

    Kim, Min Gun; Lim, Bok Kyu; Hwang, Jung Gak; Kim, Dong Youl

    2005-01-01

    Single phase bainite structure which is obtained by the conventional austempering treatment reduces the ductility of ductile cast iron. Because of the reduction of ductility it is possible to worsen the fatigue properties. Therefore, semi austempered ductile iron which is treated from α+γ is prepared to investigate the static strength and fatigue properties in comparison with fully austempered ductile iron (is treated from γ). In spite of semi austempered ductile iron shows the 86% increase of ductility. Also, semi austempered ductile iron shows the higher fatigue limit and lower fatigue crack growth rate as compared with fully austempered ductile iron. By the fractographical analysis, it is revealed that the ferrite obtained by semi austempering process brings about the plastic deformation (ductile striation) of crack tip and gives the prior path of crack propagation. The relatively low crack growth rate in semi austempered specimen is caused by above fractographical reasons

  12. New measurement technique of ductility curve for ductility-dip cracking susceptibility in Alloy 690 welds

    Energy Technology Data Exchange (ETDEWEB)

    Kadoi, Kota, E-mail: kadoi@hiroshima-u.ac.jp [Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527 (Japan); Uegaki, Takanori; Shinozaki, Kenji; Yamamoto, Motomichi [Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527 (Japan)

    2016-08-30

    The coupling of a hot tensile test with a novel in situ observation technique using a high-speed camera was investigated as a high-accuracy quantitative evaluation method for ductility-dip cracking (DDC) susceptibility. Several types of Alloy 690 filler wire were tested in this study owing to its susceptibility to DDC. The developed test method was used to directly measure the critical strain for DDC and high temperature ductility curves with a gauge length of 0.5 mm. Minimum critical strains of 1.3%, 4.0%, and 3.9% were obtained for ERNiCrFe-7, ERNiCrFe-13, and ERNiCrFe-15, respectively. The DDC susceptibilities of ERNiCrFe-13 and ERNiCrFe-15 were nearly the same and quite low compared with that of ERNiCrFe-7. This was likely caused by the tortuosity of the grain boundaries arising from the niobium content of around 2.5% in the former samples. Besides, ERNiCrFe-13 and ERNiCrFe-15 indicated higher minimum critical strains even though these specimens include higher content of sulfur and phosphorus than ERNiCrFe-7. Thus, containing niobium must be more effective to improve the susceptibility compared to sulfur and phosphorous in the alloy system.

  13. New measurement technique of ductility curve for ductility-dip cracking susceptibility in Alloy 690 welds

    International Nuclear Information System (INIS)

    Kadoi, Kota; Uegaki, Takanori; Shinozaki, Kenji; Yamamoto, Motomichi

    2016-01-01

    The coupling of a hot tensile test with a novel in situ observation technique using a high-speed camera was investigated as a high-accuracy quantitative evaluation method for ductility-dip cracking (DDC) susceptibility. Several types of Alloy 690 filler wire were tested in this study owing to its susceptibility to DDC. The developed test method was used to directly measure the critical strain for DDC and high temperature ductility curves with a gauge length of 0.5 mm. Minimum critical strains of 1.3%, 4.0%, and 3.9% were obtained for ERNiCrFe-7, ERNiCrFe-13, and ERNiCrFe-15, respectively. The DDC susceptibilities of ERNiCrFe-13 and ERNiCrFe-15 were nearly the same and quite low compared with that of ERNiCrFe-7. This was likely caused by the tortuosity of the grain boundaries arising from the niobium content of around 2.5% in the former samples. Besides, ERNiCrFe-13 and ERNiCrFe-15 indicated higher minimum critical strains even though these specimens include higher content of sulfur and phosphorus than ERNiCrFe-7. Thus, containing niobium must be more effective to improve the susceptibility compared to sulfur and phosphorous in the alloy system.

  14. Evolution of dislocations and twins in a strong and ductile nanotwinned steel

    International Nuclear Information System (INIS)

    Zhou, P.; Liang, Z.Y.; Liu, R.D.; Huang, M.X.

    2016-01-01

    A twinning-induced plasticity (TWIP) steel was subjected to a simple processing route (i.e. cold rolling followed by a recovery heat treatment) suitable for large-scale industrial production, resulting in the production of a strong and ductile nanotwinned steel. This nanotwinned steel combines high yield strength (1450 MPa), high ultimate tensile strength (1600 MPa) and good ductility (25% total elongation). Detailed transmission electron microscopy observation reveals that the twin volume fraction of the nanotwinned steel remains constant during tensile deformation. This is different to the deformation behaviour of recrystallized TWIP steels whose twin volume fraction increase continuously with strain during tensile deformation. The constant twin volume fraction indicates that a maximum twin volume fraction has been reached during the cold rolling process. In contrast, the dislocation density of the nanotwinned steel increases with strain as measured by the synchrotron X-ray diffraction experiments. In other words, the plastic deformation of the nanotwinned steel is mainly accommodated by glide and multiplication of dislocations. Based on the experimental results, an analytical model was developed to capture the respective effects of dislocations and twins on the strength and ductility of the present nanotwinned steel. The modelling results indicate that the strength is contributed by both twins and dislocations while the ductility is mainly attributed to dislocation multiplication. -- Graphical abstract: (a) TEM bright field image showing intensive nanotwins in the nanotwinned steel. Selected area diffraction pattern obtained within the red circle. (b) The engineering stress–stain curve of the nanotwinned steel. Display Omitted

  15. Modelling the tearing crack growth in a ductile ferritic steel using X-FEM elements

    International Nuclear Information System (INIS)

    Simatos, A.; Prabel, B.; Marie, S.; Nedelec, M.; Combescure, A.

    2012-01-01

    Extended Finite Element Method (X-FEM) is used to model a cracked structure without meshing explicitly the crack. Indeed, the crack is represented by a discontinuity of the displacement field through additional degrees of freedom using Heaviside type function or derived from the Irwin's singular fields. Initially, the stress integration in the XFEM framework supposed to divide the cut elements into sub-triangles that are conform to the crack. This was motivated in order to integrate the behaviour accurately on both sides of the crack in particular at proximity of the crack tip where singular enrichments are present. This strategy induces field projections from the usual Gauss point configuration to a variable new one that depends on the crack position in the element. For ductile fracture modelization, this approach is not applicable, because in presence of large scale yield, the projection of internal variable fields is not conservative, in particular at proximity of the crack tip. In order to circumvent this problem, a new integration strategy was proposed by B. Prabel. It consists in using 64 Gauss points that are placed without regards to the crack position. This simple integration scheme permits to take implicitly into account the crack position and the fields in the element in an accurate and consistent way. This strategy was used in problem calculation for which the plastic radius remained small. It allowed introducing the over integrated elements in the probable propagation zone, just before plastification. In the case of ductile tearing, the plasticity is not confined near the crack tip and an improvement of the proposed strategy is made. This is then used to model large ductile crack growth in a ductile ferritic steel. To validate the predictions, the modelization is compared to a second F.E. calculation using the node release technique for the crack propagation. It is then shown that the two predictions are strictly equivalents. (authors)

  16. Rhenium Alloys as Ductile Substrates for Diamond Thin-Film Electrodes.

    Science.gov (United States)

    Halpern, Jeffrey M; Martin, Heidi B

    2014-02-01

    Molybdenum-rhenium (Mo/Re) and tungsten-rhenium (W/Re) alloys were investigated as substrates for thin-film, polycrystalline boron-doped diamond electrodes. Traditional, carbide-forming metal substrates adhere strongly to diamond but lose their ductility during exposure to the high-temperature (1000°C) diamond, chemical vapor deposition environment. Boron-doped semi-metallic diamond was selectively deposited for up to 20 hours on one end of Mo/Re (47.5/52.5 wt.%) and W/Re (75/25 wt.%) alloy wires. Conformal diamond films on the alloys displayed grain sizes and Raman signatures similar to films grown on tungsten; in all cases, the morphology and Raman spectra were consistent with well-faceted, microcrystalline diamond with minimal sp 2 carbon content. Cyclic voltammograms of dopamine in phosphate-buffered saline (PBS) showed the wide window and low baseline current of high-quality diamond electrodes. In addition, the films showed consistently well-defined, dopamine electrochemical redox activity. The Mo/Re substrate regions that were uncoated but still exposed to the diamond-growth environment remained substantially more flexible than tungsten in a bend-to-fracture rotation test, bending to the test maximum of 90° and not fracturing. The W/Re substrates fractured after a 27° bend, and the tungsten fractured after a 21° bend. Brittle, transgranular cleavage fracture surfaces were observed for tungsten and W/Re. A tension-induced fracture of the Mo/Re after the prior bend test showed a dimple fracture with a visible ductile core. Overall, the Mo/Re and W/Re alloys were suitable substrates for diamond growth. The Mo/Re alloy remained significantly more ductile than traditional tungsten substrates after diamond growth, and thus may be an attractive metal substrate for more ductile, thin-film diamond electrodes.

  17. Martensitic transformation in Cu-2be alloys induced by explosive cladding

    Science.gov (United States)

    Ganin, E.; Weiss, B. Z.; Komem, Y.

    1986-11-01

    Formation of a lath-type structure was observed at a distance greater than 100 ώm from the bond interface created by explosive cladding. The laths were found to have a strong deviation from cubic symmetry and to contain numerous internal faults. The electron diffraction patterns do not fit any equilibrium or metastable phase known to exist in a Cu-2Be alloy. Crystallographic analysis based on electron diffraction showed that the laths have an orthorhombic structure. It is postulated that the orthorhombic phase results from a shear (martensitic) transformation which takes place in the a (fcc) phase during cladding. The proposed model assumes that shear occurs on the (111) plane in the [112] direction, and the orientation relationship is suggested to be [100]ORTH(M)∥[110]α and (001)ORTH(M) II (111)α, which is consistent with electron diffraction results. The transformation causes a volume decrease of 1.1 pct. Formation of the new phase was observed only in the solution-treated specimens of Cu-2Be and not in those aged prior to cladding. It is suggested that this may be a result of different stacking fault energies.

  18. Mechanically Induced Graphite-Nanodiamonds-Phase Transformations During High-Energy Ball Milling

    Science.gov (United States)

    El-Eskandarany, M. Sherif

    2017-05-01

    Due to their unusual mechanical, chemical, physical, optical, and biological properties, nearly spherical-like nanodiamonds have received much attention as desirable advanced nanomaterials for use in a wide spectrum of applications. Although, nanodiamonds can be successfully synthesized by several approaches, applications of high temperature and/or high pressure may restrict the real applications of such strategic nanomaterials. Distinct from the current preparation approaches used for nanodiamonds preparation, here we show a new process for preparing ultrafine nanodiamonds (3-5 nm) embedded in a homogeneous amorphous-carbon matrix. Our process started from high-energy ball milling of commercial graphite powders at ambient temperature under normal atmospheric helium gas pressure. The results have demonstrated graphite-single wall carbon nanotubes-amorphous-carbon-nanodiamonds phase transformations carried out through three subsequent stages of ball milling. Based on XRD and RAMAN analyses, the percentage of nanodiamond phase + C60 (crystalline phase) produced by ball milling was approximately 81%, while the amorphous phase amount was 19%. The pressure generated on the powder together the with temperature increase upon the ball-powder-ball collision is responsible for the phase transformations occurring in graphite powders.

  19. Human Papillomavirus Induced Transformation in Cervical and Head and Neck Cancers

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Allie K. [Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229 (United States); Wise-Draper, Trisha M. [Division of Hematology/Oncology, University of Cincinnati Medical Center, University of Cincinnati, Cincinnati, OH 45229 (United States); Wells, Susanne I., E-mail: Susanne.Wells@cchmc.org [Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229 (United States)

    2014-09-15

    Human papillomavirus (HPV) is one of the most widely publicized and researched pathogenic DNA viruses. For decades, HPV research has focused on transforming viral activities in cervical cancer. During the past 15 years, however, HPV has also emerged as a major etiological agent in cancers of the head and neck, in particular squamous cell carcinoma. Even with significant strides achieved towards the screening and treatment of cervical cancer, and preventive vaccines, cervical cancer remains the leading cause of cancer-associated deaths for women in developing countries. Furthermore, routine screens are not available for those at risk of head and neck cancer. The current expectation is that HPV vaccination will prevent not only cervical, but also head and neck cancers. In order to determine if previous cervical cancer models for HPV infection and transformation are directly applicable to head and neck cancer, clinical and molecular disease aspects must be carefully compared. In this review, we briefly discuss the cervical and head and neck cancer literature to highlight clinical and genomic commonalities. Differences in prognosis, staging and treatment, as well as comparisons of mutational profiles, viral integration patterns, and alterations in gene expression will be addressed.

  20. Hydrothermal syntheses and anion-induced structural transformation of three Cadmium phosphonates

    Science.gov (United States)

    Hu, Han; Zhai, Fupeng; Liu, Xiaofeng; Ling, Yun; Chen, Zhenxia; Zhou, Yaming

    2018-05-01

    Three cadmium phosphonate coordinated polymers, namely as [Cd5(ptz)3(SO4)2(5H2O)]·6H2O (Cdptz-1), [Cd3(ptz)2(Cl)2(4H2O)]·2H2O (Cdptz-2) and [Cd4(ptz)2(SO4)(Cl)(OH)H2O]·H2O (Cdptz-3) have been hydrothermally synthesized using 4-(1,2,4-triazol-4-yl)phenylphosphonic acid (H2ptz) as ligand. Single crystal X-ray analyses revealed Cdptz-2 as layered structure and Cdptz-1,3 as pillar-layered structures with Cl- or SO42- as bridging anions. Due to the weak bonding between metal and anions, Cdptz-1 and 2 can reversibly convert into each other by simple immersing in the corresponding solution at room temperature. While the transformations between Cdptz-1,2 and Cdptz-3 can only happen under hydrothermal condition. The causes for the transformation involve the metal-ligand bond breaking/formation, replacement of anions and enhancement/decrement of the network dimensionality.

  1. Human Papillomavirus Induced Transformation in Cervical and Head and Neck Cancers

    International Nuclear Information System (INIS)

    Adams, Allie K.; Wise-Draper, Trisha M.; Wells, Susanne I.

    2014-01-01

    Human papillomavirus (HPV) is one of the most widely publicized and researched pathogenic DNA viruses. For decades, HPV research has focused on transforming viral activities in cervical cancer. During the past 15 years, however, HPV has also emerged as a major etiological agent in cancers of the head and neck, in particular squamous cell carcinoma. Even with significant strides achieved towards the screening and treatment of cervical cancer, and preventive vaccines, cervical cancer remains the leading cause of cancer-associated deaths for women in developing countries. Furthermore, routine screens are not available for those at risk of head and neck cancer. The current expectation is that HPV vaccination will prevent not only cervical, but also head and neck cancers. In order to determine if previous cervical cancer models for HPV infection and transformation are directly applicable to head and neck cancer, clinical and molecular disease aspects must be carefully compared. In this review, we briefly discuss the cervical and head and neck cancer literature to highlight clinical and genomic commonalities. Differences in prognosis, staging and treatment, as well as comparisons of mutational profiles, viral integration patterns, and alterations in gene expression will be addressed

  2. Ion induced transformation of polymer films into diamond-like carbon incorporating silver nano particles

    International Nuclear Information System (INIS)

    Schwarz, Florian P.

    2010-01-01

    Silver containing diamond-like carbon (DLC) is an interesting material for medical engineering from several points of view. On the one hand DLC provides high mechanical robustness. It can be used as biocompatible and wear resistant coating for joint replacing implants. On the other hand silver has antimicrobial properties, which could reduce post-operative inflammations. However conventional production of Ag-DLC by co-deposition of silver and carbon in a plasma process is problematic since it does not allow for a separate control of nano particle morphology and matrix properties. In this work an alternative production method has been developed to circumvent this problem. In metall-DLC-production by ion implantation into a nano composite, silver nano particles are initially formed in solution and then incorporated within a polymer matrix. Finally the polymer is transformed into DLC by ion implantation. The aspects and single steps of this method were investigated with regard to the resulting material's properties. The goal was to design an economically relevant deposition method. Based on experimental results a model of the transformation process has been established, which has also been implemented in a computer simulation. Finally the antibacterial properties of the material have been checked in a biomedical test. Here a bacterial killing rate of 90% could be achieved. (orig.)

  3. Structural and morphological transformations of TiO2 nanotube arrays induced by excimer laser treatment

    International Nuclear Information System (INIS)

    Hsu, Ming-Yi; Thang, Nguyen Van; Wang Chih; Leu Jihperng

    2012-01-01

    The structural and morphological transformations of TiO 2 nanotube arrays (TNAs) treated by excimer laser annealing (ELA) were investigated as a function of the laser fluence using parallel and tilted modes. Results showed that the crystallinity of the ELA-treated TNAs reached only about 50% relative to that of TNAs treated by furnace anneal at 400 °C for 1 h. The phase transformation starts from the top surface of the TNAs with surface damage resulting from short penetration depth and limited one-dimensional heat transport from the surface to the bottom under extremely short pulse duration (25 ns) of the excimer laser. When a tilted mode was used, the crystallinity of TNAs treated by ELA at 85° was increased to 90% relative to that by the furnace anneal. This can be attributed to the increased area of the laser energy interaction zone and better heat conduction to both ends of the TNAs. - Highlights: ► We examined the morphology and microstructure of TNAs treated by ELA. ► Crystallinity of parallel ELA-treated TNAs reached ∼50% of furnace anneal. ► Tilted ELA at 85o enhanced the degree of crystallization in TNAs to 90%.

  4. Ductile flow by water-assisted cataclasis

    Science.gov (United States)

    den Brok, Bas

    2003-04-01

    In the presence of water otherwise brittle materials may deform macroscopically ductile by water-assisted cataclastic creep. This is possible as long as (i) solubility is high enough, so that stress-corrosion can occur, and (ii) local stress is low enough, to that fracturing remains subcritical. Water-assisted cataclastic creep (WACC) may play an important role in the middle and lower continental crust where mineral solubilities are high and stresses low. WACC is a poorly understood deformation process. Experiments were performed on very soluble brittle salts (Na-chlorate; K-alum) to study microstructure development by WACC. The experiments were carried out at room temperature and atmospheric pressure in a small see-through vessel. In this way the cataclastic deformation process could be studied "in-situ" under the microscope. Crystals were loaded in the presence of saturated salt solution. It appeared that originally straight mineral surfaces were instable when kept under stress. Grooves (or channels) slowly developed in the surface by local dissolution. These grooves behave like so-called Grinfeld instabilities. They develop because the energy of a grooved surface under stress is lower than the energy of a straight surface under stress. The grooves may deepen and turn into subcritical cracks when local stress further increases. These cracks propagate slowly. They propagate parallel to sigma1 but also at an angle and even perpendicular to sigma1, often following crystallographically controlled directions. The fractures mostly change direction while propagating, locally making turns of more than 180 degrees. Irregular fracture fragments thus develop. The fractures may migrate sideways (as with grain bounday migration) probably by solution-redeposition driven by differences in stress between both sides of the fracture. Thus the shape of the fragments changes. The size of the fracture fragments seems to be controlled by the distance of the grooves, which decreases

  5. Arsenic transformation predisposes human skin keratinocytes to UV-induced DNA damage yet enhances their survival apparently by diminishing oxidant response

    International Nuclear Information System (INIS)

    Sun Yang; Kojima, Chikara; Chignell, Colin; Mason, Ronald; Waalkes, Michael P.

    2011-01-01

    Inorganic arsenic and UV, both human skin carcinogens, may act together as skin co-carcinogens. We find human skin keratinocytes (HaCaT cells) are malignantly transformed by low-level arsenite (100 nM, 30 weeks; termed As-TM cells) and with transformation concurrently undergo full adaptation to arsenic toxicity involving reduced apoptosis and oxidative stress response to high arsenite concentrations. Oxidative DNA damage (ODD) is a possible mechanism in arsenic carcinogenesis and a hallmark of UV-induced skin cancer. In the current work, inorganic arsenite exposure (100 nM) did not induce ODD during the 30 weeks required for malignant transformation. Although acute UV-treatment (UVA, 25 J/cm 2 ) increased ODD in passage-matched control cells, once transformed by arsenic to As-TM cells, acute UV actually further increased ODD (> 50%). Despite enhanced ODD, As-TM cells were resistant to UV-induced apoptosis. The response of apoptotic factors and oxidative stress genes was strongly mitigated in As-TM cells after UV exposure including increased Bcl2/Bax ratio and reduced Caspase-3, Nrf2, and Keap1 expression. Several Nrf2-related genes (HO-1, GCLs, SOD) showed diminished responses in As-TM cells after UV exposure consistent with reduced oxidant stress response. UV-exposed As-TM cells showed increased expression of cyclin D1 (proliferation gene) and decreased p16 (tumor suppressor). UV exposure enhanced the malignant phenotype of As-TM cells. Thus, the co-carcinogenicity between UV and arsenic in skin cancer might involve adaptation to chronic arsenic exposure generally mitigating the oxidative stress response, allowing apoptotic by-pass after UV and enhanced cell survival even in the face of increased UV-induced oxidative stress and increased ODD. - Highlights: → Arsenic transformation adapted to UV-induced apoptosis. → Arsenic transformation diminished oxidant response. → Arsenic transformation enhanced UV-induced DNA damage.

  6. c-Jun/AP-1 pathway-mediated cyclin D1 expression participates in low dose arsenite-induced transformation in mouse epidermal JB6 Cl41 cells

    International Nuclear Information System (INIS)

    Zhang Dongyun; Li Jingxia; Gao Jimin; Huang Chuanshu

    2009-01-01

    Arsenic is a well-documented human carcinogen associated with skin carcinogenesis. Our previous work reveals that arsenite exposure is able to induce cell transformation in mouse epidermal cell JB6 Cl41 through the activation of ERK, rather than JNK pathway. Our current studies further evaluate downstream pathway in low dose arsenite-induced cell transformation in JB6 Cl41 cells. Our results showed that treatment of cells with low dose arsenite induced activation of c-Jun/AP-1 pathway, and ectopic expression of dominant negative mutant of c-Jun (TAM67) blocked arsenite-induced transformation. Furthermore, our data indicated that cyclin D1 was an important downstream molecule involved in c-Jun/AP-1-mediated cell transformation upon low dose arsenite exposure, because inhibition of cyclin D1 expression by its specific siRNA in the JB6 Cl41 cells resulted in impairment of anchorage-independent growth of cells induced by low dose arsenite. Collectively, our results demonstrate that c-Jun/AP-1-mediated cyclin D1 expression is at least one of the key events implicated in cell transformation upon low dose arsenite exposure

  7. Transforming growth factor β1 induces the expression of collagen type I by DNA methylation in cardiac fibroblasts.

    Directory of Open Access Journals (Sweden)

    Xiaodong Pan

    Full Text Available Transforming growth factor-beta (TGF-β, a key mediator of cardiac fibroblast activation, has a major influence on collagen type I production. However, the epigenetic mechanisms by which TGF-β induces collagen type I alpha 1 (COL1A1 expression are not fully understood. This study was designed to examine whether or not DNA methylation is involved in TGF-β-induced COL1A1 expression in cardiac fibroblasts. Cells isolated from neonatal Sprague-Dawley rats were cultured and stimulated with TGF-β1. The mRNA levels of COL1A1 and DNA methyltransferases (DNMTs were determined via quantitative polymerase chain reaction and the protein levels of collagen type I were determined via Western blot as well as enzyme-linked immunosorbent assay. The quantitative methylation of the COL1A1 promoter region was analyzed using the MassARRAY platform of Sequenom. Results showed that TGF-β1 upregulated the mRNA expression of COL1A1 and induced the synthesis of cell-associated and secreted collagen type I in cardiac fibroblasts. DNMT1 and DNMT3a expressions were significantly downregulated and the global DNMT activity was inhibited when treated with 10 ng/mL of TGF-β1 for 48 h. TGF-β1 treatment resulted in a significant reduction of the DNA methylation percentage across multiple CpG sites in the rat COL1A1 promoter. Thus, TGF-β1 can induce collagen type I expression through the inhibition of DNMT1 and DNMT3a expressions as well as global DNMT activity, thereby resulting in DNA demethylation of the COL1A1 promoter. These findings suggested that the DNMT-mediated DNA methylation is an important mechanism in regulating the TGF-β1-induced COL1A1 gene expression.

  8. Dynamic Monitoring of Cellular Remodeling Induced by the Transforming Growth Factor-β1

    Directory of Open Access Journals (Sweden)

    Kubala Lukáš

    2009-01-01

    Full Text Available Abstract The plasticity of differentiated adult cells could have a great therapeutic potential, but at the same time, it is characteristic of progression of serious pathological states such as cancer and fibrosis. In this study, we report on the application of a real-time noninvasive system for dynamic monitoring of cellular plasticity. Analysis of the cell impedance profile recorded as cell index using a real-time cell analyzer revealed its significant increase after the treatment of prostate epithelial cells with the transforming growth factor-β1. Changes in the cell index profile were paralleled with cytoskeleton rebuilding and induction of epithelial–mesenchymal transition and negatively correlated with cell proliferation. This novel application of such approach demonstrated a great potential of the impedance-based system for noninvasive and real-time monitoring of cellular fate.

  9. Numerical Study of the Plasticity-Induced Stabilization Effect on Martensitic Transformations in Shape Memory Alloys

    Science.gov (United States)

    Junker, Philipp; Hempel, Philipp

    2017-12-01

    It is well known that plastic deformations in shape memory alloys stabilize the martensitic phase. Furthermore, the knowledge concerning the plastic state is crucial for a reliable sustainability analysis of construction parts. Numerical simulations serve as a tool for the realistic investigation of the complex interactions between phase transformations and plastic deformations. To account also for irreversible deformations, we expand an energy-based material model by including a non-linear isotropic hardening plasticity model. An implementation of this material model into commercial finite element programs, e.g., Abaqus, offers the opportunity to analyze entire structural components at low costs and fast computation times. Along with the theoretical derivation and expansion of the model, several simulation results for various boundary value problems are presented and interpreted for improved construction designing.

  10. UV-induced photochemical transformations of citrate-capped silver nanoparticle suspensions

    International Nuclear Information System (INIS)

    Gorham, Justin M.; MacCuspie, Robert I.; Klein, Kate L.; Fairbrother, D. Howard; Holbrook, R. David

    2012-01-01

    Due to the increasing use of silver nanoparticles (AgNPs) in consumer products, it is essential to understand how variables, such as light exposure, may change the physical and chemical characteristics of AgNP suspensions. To this end, the effect of 300 nm ultraviolet (UV) light on (20, 40, 60 and 80) nm citrate-capped AgNP suspensions has been investigated. As a consequence of irradiation, the initial yellow hue of the AgNP suspensions is transformed towards a near colorless solution due to the loss of the surface plasmon resonance (SPR) absorbance. The decrease in SPR absorbance followed a first-order decay process for all particle sizes with a rate constant that increased linearly with the AgNP specific surface area and non-linearly with light intensity. The rate of loss of the SPR absorbance decreased with increasing citrate concentration, suggesting a surface-mediated transformation. Absorbance, atomic force microscopy, and dynamic light scattering results all indicated that AgNP photolysis was accompanied by a diameter decrease and occasional aggregation. Furthermore, in situ transmission electron microscopy imaging using a specialized liquid cell also showed a decrease in the particle size and the formation of a core–shell structure in UV-exposed AgNPs. X-ray photoelectron spectroscopy analysis suggested that this shell consisted of oxidized silver. The SPR in UV-exposed AgNP suspensions could be regenerated by addition of a strong reducing agent (NaBH 4 ), supporting the idea that oxidized silver is present after photolysis. Evidence for UV-enhanced dissolution and the production of silver ions was obtained with the Donnan membrane technique. This study reveals that the physico-chemical properties of aqueous AgNP suspensions will change significantly upon exposure to UV light, with implications for environmental health and safety risk assessments.

  11. Ayahuasca-Induced Interiority Transformation in 3 Middle-Aged Educated Women

    Directory of Open Access Journals (Sweden)

    Ron Reminick

    2014-02-01

    Full Text Available This study focuses upon 3 women whose lives had become conflictful, emotionally painful and anomic. The consequences of pain crosses gender and culture lines, especially if one is not aware of their afflictions or knows no way to a fulfilling life. Through the life histories of these 3 women I trace their struggle out of past life experience into an “ayahuasca world” of unlimited possibilities and transformative experience. They came to know themselves more clearly. Many women, usually educated and literate, have the resources and ability to change their lives by cultivating new relationships, assuming new occupations, or adopting more fulfilling social roles. A greater number who are not well-educated or who live by tradition may not find their way to successful adaptation. Many ethnographic studies describe tradition in change, or the effects of globalization on indigenous societies. Some record the use of ayahuasca, but do not study the outcome. We need to nurture the genius that has moved humans into higher levels of consciousness since time immemorial; the gifts of the few who have transcended normal consciousness, nurtured their own spirituality, and who have become leaders and teachers. Rites of passage are universal in human society and suggest the need for identity development and cultural sustenance. They propel the human mind into deeper levels of consciousness and conscience. This study is about 3 women’s spiritual quest for a transformative experience they can share with others. It describes the possibility of a new consciousness through guided shamanic ritual.

  12. Studies on adaptive response of lymphocyte transformation induced by low-dose irradiation

    International Nuclear Information System (INIS)

    Du Zeji; Su Liaoyuan; Tian Hailin; Zou Huawei

    1995-10-01

    Human peripheral blood lymphocytes stimulated by mitogen in vitro for 24 h were exposed to low-dose γ-ray irradiation (0.5∼4.0 cGy, adaptive dose). They showed an adaptive response to the inhibition of 3 H-TdR incorporation by subsequent higher acute doses of γ-ray (challenge dose). At the interval of 24 h between adaptive dose and challenge dose, the strongest adaptive response induced by low-dose irradiation was found. It is also found that the response induced by 1.0 cGy of adaptive dose was more obvious than that by other doses and that 3.0 Gy of challenge dose produced the strongest adaptive response. As the challenge doses increased, the adaptive response reduced. (2 figs., 2 tabs.)

  13. Friction welding of ductile cast iron using interlayers

    International Nuclear Information System (INIS)

    Winiczenko, Radoslaw; Kaczorowski, Mieczyslaw

    2012-01-01

    Highlights: → The results of the study of the friction welding of ductile cast iron using interlayers are presented. → The results of the analysis shows that the joint has the tensile strength compared to that of basic material. → In case of ductile cast iron, it is possible to reach the tensile strength equals even 700 MPa. → The process of friction welding was accompanied with diffusion of Cr, Ni and C atoms across the interface. -- Abstract: In this paper, ductile cast iron-austenitic stainless steel, ductile cast iron-pure Armco iron and ductile cast iron-low carbon steel interlayers were welded, using the friction welding method. The tensile strength of the joints was determined, using a conventional tensile test machine. Moreover, the hardness across the interface of materials was measured on metallographic specimens. The fracture surface and microstructure of the joints was examined using either light stereoscope microscopy as well as electron microscopy. In this case, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were applied. The results of the analysis shows that the joint has the tensile strength compared to that of basic material. In case of ductile cast iron, it is possible to reach the tensile strength equals even 700 MPa. It was concluded that the process of friction welding was accompanied with diffusion of Cr, Ni and C atoms across the ductile cast iron-stainless steel interface. This leads to increase in carbon concentration in stainless steel where chromium carbides were formed, the size and distribution of which was dependent on the distance from the interface.

  14. Influence of grain structure on the deformation mechanism in martensitic shear reversion-induced Fe-16Cr-10Ni model austenitic alloy with low interstitial content: Coarse-grained versus nano-grained/ultrafine-grained structure

    Energy Technology Data Exchange (ETDEWEB)

    Challa, V.S.A. [Laboratory for Excellence in Advanced Steel Research, Department of Metallurgical, Materials Engineering, and Biomedical Engineering, University of Texas at El Paso, El Paso, TX 79968 (United States); Misra, R.D.K., E-mail: dmisra2@utep.edu [Laboratory for Excellence in Advanced Steel Research, Department of Metallurgical, Materials Engineering, and Biomedical Engineering, University of Texas at El Paso, El Paso, TX 79968 (United States); Somani, M.C. [Center for Advanced Steels Research, The University of Oulu, P.O. Box 4200, 90014 Oulu (Finland); Wang, Z.D. [State Key Laboratory for Rolling and Automation, Northeastern University, 3-11 Wenhua Road, Shenyang 110819 (China)

    2016-04-20

    Nanograined/ultrafine-grained (NG/UFG) materials characterized by high strength-high ductility combination are excellent vehicles to obtain an unambiguous understanding of deformation mechanisms vis-à-vis their coarse-grained counterparts. In this context, the innovative concept of phase reversion-induced NG/UFG structure enabled achieving high strength besides comparable ductility, for instance, in metastable austenitic stainless steels. In the phase reversion process, severe deformation of austenite at room temperature (typically ~60–80%) transforms face-centered cubic austenite (γ) to body centered cubic martensite (α′). Upon annealing, martensite reverts to austenite leading to extensive grain refinement. The objective of the present study to fundamentally understand the deformation mechanisms in NG/UFG structure in relation to that of the coarse-grained (CG) structure was accomplished by combining depth-sensing nanoscale experiments on an Fe-16Cr-10Ni model austenitic alloy conducted at different strain rates, followed by the study of structural evolution in the deformed zone using transmission electron microscopy (TEM). In the high strength NG/UFG steel (YS~585 MPa), stacking faults and nanotwins contributed to the enhanced ductility (El~35%), while in the case of low strength (YS~260 MPa) coarse-grained (CG) counterpart, ductility was also high (El~40%), but chiefly due to strain-induced martensite, which points to a clear case of grain size effect (and the corresponding level of strength). The distinct change in the deformation mechanism from stacking faults and twinning-induced plasticity (TWIP) in the NG structure to transformation-induced plasticity (TRIP) in the CG structure is elucidated in terms of austenite stability-strain energy relationship. The insights on the relationship between grain structure (and strength) and deformation mechanisms are envisaged to be important in providing a new direction for the futuristic design of high strength

  15. Magmatism and crustal extension: Constraining activation of the ductile shearing along the Gediz detachment, Menderes Massif (western Turkey)

    Science.gov (United States)

    Rossetti, Federico; Asti, Riccardo; Faccenna, Claudio; Gerdes, Axel; Lucci, Federico; Theye, Thomas

    2017-06-01

    The Menderes Massif of western Turkey is a key area to study feedback relationships between magma generation/emplacement and activation of extensional detachment tectonics. Here, we present new textural analysis and in situ U-(Th)-Pb titanite dating from selected samples collected in the transition from the undeformed to the mylonitized zones of the Salihli granodiorite at the footwall of the Neogene, ductile-to-brittle, top-to-the-NNE Gediz-Alaşheir (GDF) detachment fault. Ductile shearing was accompanied by the fluid-mediated sub-solidus transformation of the granodiorite to orthogneiss, which occurred at shallower crustal levels and temperatures compatible with the upper greenschist-to-amphibolite facies metamorphic conditions (530-580 °C and P system ages during fluid-assisted syn-tectonic re-crystallisation in the transition from magma crystallization and emplacement (at 16-17 Ma) to the syn-tectonic, solid-state shearing (at 14-15 Ma). A minimum time lapse of ca. 1-2 Ma is then inferred between the crustal emplacement of the Salihli granodiorite and nucleation of the ductile extensional shearing along the Gediz detachment. The reconstruction of the cooling history of the Salihli granodiorite documents a punctuated evolution dominated by two episodes of rapid cooling, between 14 Ma and 12 Ma ( 100 °C/Ma) and between 3 and 2 Ma ( 105 °C/Ma). We relate the first episode to nucleation and development of post-emplacement of ductile shearing along the GDF and the second to brittle high-angle faulting, respectively. Our dataset suggests that in the Menderes Massif the activation of ductile extension was a consequence, rather than the cause, of magma emplacement in the extending crust.

  16. Partial transformation from fast to slow muscle fibers induced by deafferentation of capsaicin-sensitive muscle afferents.

    Science.gov (United States)

    Brunetti, O; Barazzoni, A M; Della Torre, G; Clavenzani, P; Pettorossi, V E; Bortolami, R

    1997-11-01

    Mechanical and histochemical characteristics of the lateral gastrocnemius (LG) muscle of the rat were examined 21 days after capsaicin injection into the LG muscle. The capsaicin caused a decrease in generation rate of twitch and tetanic tension and an increase in fatigue resistance of LG muscle. The histochemical muscle fiber profile evaluated by myosin adenosine triphosphatase and reduced nicotinamide adenine dinucleotide tetrazolium reductase methods showed an increase of type I and IIC fibers and a decrease of the type IIB in whole muscle, and a decrease of the IIA, IIX fibers in the red part accompanied by their increase in the white part. Therefore the capsaicin treatment, which selectively eliminated fibers belonging to the III and IV groups of muscle afferents, induced muscle fiber transformation from fast contracting fatiguing fibers to slowly contracting nonfatiguing ones.

  17. Measurement of lattice rotations and internal stresses in over one hundred individual grains during a stress-induced martensitic transformation

    Directory of Open Access Journals (Sweden)

    Hachi Younes El

    2015-01-01

    Full Text Available To better understand the properties of polycrystals at a microscopic scale during cyclic mechanical loading we have measured the relationship between grain orientations, their positions inside the sample and their internal stresses. In this work, in-situ 3DXRD technique was performed on over hundred grains during the stress-induced martensitic transformation in a Cu-Al-Be shape memory alloy. Information about the position, orientation, and stress field was obtained for each austenitic grain. These results have been used to develop a procedure that allows automatic processing for a large number of grains, matching them during loading and leads to a quantitative stress field. A strong heterogeneity of stress state between the grains at the surface and in the volume is evident.

  18. Transforming growth factor β (CiTGF-β) gene expression is induced in the inflammatory reaction of Ciona intestinalis.

    Science.gov (United States)

    Vizzini, Aiti; Di Falco, Felicia; Parrinello, Daniela; Sanfratello, Maria Antonietta; Cammarata, Matteo

    2016-02-01

    Transforming growth factor (TGF-β) is a well-known component of a regulatory cytokines superfamily that has pleiotropic functions in a broad range of cell types and is involved, in vertebrates, in numerous physiological and pathological processes. In the current study, we report on Ciona intestinalis molecular characterisation and expression of a transforming growth factor β homologue (CiTGF-β). The gene organisation, phylogenetic tree and modelling supported the close relationship with the mammalian TGF suggesting that the C. intestinalis TGF-β gene shares a common ancestor in the chordate lineages. Functionally, real-time PCR analysis showed that CiTGF-β was transcriptionally upregulated in the inflammatory process induced by LPS inoculation, suggesting that is involved in the first phase and significant in the secondary phase of the inflammatory response in which cell differentiation occurs. In situ hybridisation assays revealed that the genes transcription was upregulated in the pharynx, the main organ of the ascidian immune system, and expressed by cluster of hemocytes inside the pharynx vessels. These data supported the view that CiTGF-β is a potential molecule in immune defence systems against bacterial infection. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. [Detection of fps tumor antigen with mono-specific anti-fps serum in tumors induced by acute transforming ALV].

    Science.gov (United States)

    Wang, Yixin; Chen, Hao; Zhao, Peng; Li, Jianliang; Cui, Zhizhong

    2013-03-04

    To prepare anti-fps mono-specific serum, and detect the fps antigen in tumors induced by acute transforming avian leukosis/sarcoma virus containing v-fps oncogene. Two part of v-fps gene was amplified by RT-PCR using the Fu-J viral RNA as the template. Mono-specific serum was prepared by immuning Kunming white mouse with both two recombinant infusion proteins expressed by the prokaryotic expression system. Indirect immunofluorescent assay was used to detect fps antigen in tumor tissue suspension cells and CEF infected by sarcoma supernatant. Immunohistochemical method was used to detect fps antigen in tumor tissue. The mouse mono-specific serum was specific as it had no cross reaction with classical ALV-J strains. The result reveals that the tumor tissue suspension cells, the CEF infected by sarcoma supernatant, and the slice immunohistochemistry of the sarcoma showed positive results. The anti-fps mono-specific serum was prepared, and the detection method was established, which laid the foundation for the study of viral biological characteristics and mechanism of tumourgenesis of acute transforming avian leukosis/sarcoma virus containing v-fps oncogene.

  20. Trapping induced Neff and electrical field transformation at different temperatures in neutron irradiated high resistivity silicon detectors

    International Nuclear Information System (INIS)

    Eremin, V.; Li, Z.; Iljashenko, I.

    1994-02-01

    The trapping of both non-equilibrium electrons and holes by neutron induced deep levels in high resistivity silicon planar detectors have been observed. In the experiments Transient Current and Charge Techniques, with short laser light pulse excitation have been applied at temperature ranges of 77--300 k. Light pulse illumination of the front (p + ) and back (n + ) contacts of the detectors showed effective trapping and detrapping, especially for electrons. At temperatures lower than 150 k, the detrapping becomes non-efficient, and the additional negative charge of trapped electrons in the space charge region (SCR) of the detectors leads to dramatic transformations of the electric field due to the distortion of the effective space charge concentration N eff . The current and charge pulses transformation data can be explained in terms of extraction of electric field to the central part of the detector from the regions near both contacts. The initial field distribution may be recovered immediately by dropping reverse bias, which injects both electrons and holes into the space charge region. In the paper, the degree of the N eff distortions among various detectors irradiated by different neutron fluences are compared

  1. The Investigation on Strain Strengthening Induced Martensitic Phase Transformation of Austenitic Stainless Steel: A Fundamental Research for the Quality Evaluation of Strain Strengthened Pressure Vessel

    Science.gov (United States)

    Li, Bo; Cai Ren, Fa; Tang, Xiao Ying

    2018-03-01

    The manufacture of pressure vessels with austenitic stainless steel strain strengthening technology has become an important technical means for the light weight of cryogenic pressure vessels. In the process of increasing the strength of austenitic stainless steel, strain can induce the martensitic phase transformation in austenite phase. There is a quantitative relationship between the transformation quantity of martensitic phase and the basic mechanical properties. Then, the martensitic phase variables can be obtained by means of detection, and the mechanical properties and safety performance are evaluated and calculated. Based on this, the quantitative relationship between strain hardening and deformation induced martensite phase content is studied in this paper, and the mechanism of deformation induced martensitic transformation of austenitic stainless steel is detailed.

  2. Low-pH-induced transformation of bilayer membrane into bicontinuous cubic phase in dioleoylphosphatidylserine/monoolein membranes.

    Science.gov (United States)

    Okamoto, Yoshihide; Masum, Shah Md; Miyazawa, Haruna; Yamazaki, Masahito

    2008-04-01

    Cubic biomembranes, nonbilayer membranes with connections in three-dimensional space that have a cubic symmetry, have been observed in various cells. Interconversion between the bilayer liquid-crystalline (L(alpha)) phase and cubic phases attracted much attention in terms of both biological and physicochemical aspects. Herein we report the pH effect on the phase and structure of dioleoylphosphatidylserine (DOPS)/monoolein (MO) membranes under a physiological ion concentration condition, which was revealed by small-angle X-ray scattering (SAXS) measurement. At neutral pH, DOPS/MO membranes containing high concentrations of DOPS were in the L(alpha) phase. First, the pH effect on the phase and structure of the multilamellar vesicles (MLVs) of the DOPS/MO membranes preformed at neutral pH was investigated by adding various low-pH buffers into the MLV suspension. For 20%-DOPS/80%-MO MLVs, at and below pH 2.9, a transition from the L(alpha) to cubic (Q(224)) phase occurred within 1 h. This phase transition was reversible; a subsequent increase in pH to a neutral one in the membrane suspension transformed the cubic phase into the original L(alpha) phase. Second, we found that a decrease in pH transformed large unilamellar vesicles of DOPS/MO membranes into the cubic phase under similar conditions. We have proposed the mechanism of the low-pH-induced phase transition and also made a quantitative analysis on the critical pH of the phase transition. This finding is the first demonstration that a change in pH can induce a reversible phase transition between the L(alpha) and cubic phases of lipid membranes within 1 h.

  3. Increased radiation-induced transformation in C3H/10T1/2 cells after transfer of an exogenous c-myc gene

    International Nuclear Information System (INIS)

    Sorrentino, V.; Drozdoff, V.; Zeitz, L.; Fleissner, E.

    1987-01-01

    C3H/10T 1/2 cells were infected with a retroviral vector expressing a mouse c-myc oncogene and a drug-selection marker. The resulting cells, morphologically indistinguishable from C3H/10T l/1, displayed a greatly enhanced sensitivity to neoplastic transformation by ionizing radiation or by a chemical carcinogen. Constitutive expression of myc therefore appears to synergize with an initial carcinogenic event, providing a function analogous to a subsequent event that apparently is required for the neoplastic transformation of these cells. This cell system should prove useful in exploring early stages in radiation-induced transformation

  4. Microelectrode array-induced neuronal alignment directs neurite outgrowth: analysis using a fast Fourier transform (FFT).

    Science.gov (United States)

    Radotić, Viktorija; Braeken, Dries; Kovačić, Damir

    2017-12-01

    Many studies have shown that the topography of the substrate on which neurons are cultured can promote neuronal adhesion and guide neurite outgrowth in the same direction as the underlying topography. To investigate this effect, isotropic substrate-complementary metal-oxide-semiconductor (CMOS) chips were used as one example of microelectrode arrays (MEAs) for directing neurite growth of spiral ganglion neurons. Neurons were isolated from 5 to 7-day-old rat pups, cultured 1 day in vitro (DIV) and 4 DIV, and then fixed with 4% paraformaldehyde. For analysis of neurite alignment and orientation, fast Fourier transformation (FFT) was used. Results revealed that on the micro-patterned surface of a CMOS chip, neurons orient their neurites along three directional axes at 30, 90, and 150° and that neurites aligned in straight lines between adjacent pillars and mostly followed a single direction while occasionally branching perpendicularly. We conclude that the CMOS substrate guides neurites towards electrodes by means of their structured pillar organization and can produce electrical stimulation of aligned neurons as well as monitoring their neural activities once neurites are in the vicinity of electrodes. These findings are of particular interest for neural tissue engineering with the ultimate goal of developing a new generation of MEA essential for improved electrical stimulation of auditory neurons.

  5. Online analytical investigations on solvent-, temperature- and water vapour-induced phase transformations of citric acid

    Energy Technology Data Exchange (ETDEWEB)

    Helmdach, L.; Ulrich, J. [Martin-Luther-Universitaet Halle-Wittenberg, Zentrum fuer Ingenieurwissenschaft, Verfahrenstechnik/TVT, Halle (Saale) (Germany); Feth, M.P. [Sanofi-Aventis Deutschland GmbH, Chemical and Process Development Frankfurt Chemistry, Frankfurt (Germany)

    2012-09-15

    It was demonstrated exemplarily for the crystallization of citric acid that the usage of an ultrasound device as well as Raman spectroscopy enables the inline measurement and the control of phase transitions. The influence of different solvent compositions (water and ethanol-water) on the crystallization of citric acid was investigated. By increasing the ethanol content the transformation point was shifted towards higher temperatures. In addition, a strong impact on the nucleation point as well as on the crystal habit was detected in ethanol-water mixtures. The results lead to the assumption that a citric acid solvate exists, which is, however, highly unstable upon isolation from mother liquor and converts fast into the known anhydrate or monohydrate forms of citric acid. The presence of such a solvate, however, could not be proven during this study. Furthermore, factors such as temperature and humidity which might influence the phase transition of the solid product were analyzed by Hotstage-Raman Spectroscopy and Water Vapor Sorption Gravimetry-Dispersive Raman Spectroscopy. Both, temperature as well as humidity show a strong influence on the behaviour of CAM. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Man-induced transformation of mountain meadow soils of Aragats mountain massif (Armenia)

    Science.gov (United States)

    Avetisyan, M. H.

    2018-01-01

    The article considers issues of degradation of mountain meadow soils of the Aragats mountain massif of the Republic of Armenia and provides the averaged research results obtained for 2013 and 2014. The present research was initiated in the frames of long-term complex investigations of agroecosystems of Armenia’s mountain massifs and covered sod soils of high mountain meadow pasturelands and meadow steppe grasslands lying on southern slope of Mt. Aragats. With a purpose of studying the peculiarities of migration and transformation of flows of major nutrients namely carbon, nitrogen, phosphorus in study mountain meadow and meadow steppe belts of the Aragats massif we investigated water migration of chemical elements and regularities of their leaching depending on different belts. Field measurement data have indicated that organic carbon and humus in a heavily grazed plot are almost twice as low as on a control site. Lysimetric data analysis has demonstrated that heavy grazing and illegal deforestation have brought to an increase in intrasoil water acidity. The results generated from this research support a conclusion that a man’s intervention has brought to disturbance of structure and nutrient and water regimes of soils and loss of significant amounts of soil nutrients throughout the studied region.

  7. Endoglin negatively regulates transforming growth factor beta1-induced profibrotic responses in intestinal fibroblasts.

    LENUS (Irish Health Repository)

    Burke, J P

    2012-02-01

    BACKGROUND: Fibroblasts isolated from strictures in Crohn\\'s disease (CD) exhibit reduced responsiveness to stimulation with transforming growth factor (TGF) beta1. TGF-beta1, acting through the smad pathway, is critical to fibroblast-mediated intestinal fibrosis. The membrane glycoprotein, endoglin, is a negative regulator of TGF-beta1. METHODS: Intestinal fibroblasts were cultured from seromuscular biopsies of patients undergoing intestinal resection for CD strictures or from control patients. Endoglin expression was assessed using confocal microscopy, flow cytometry and western blot. The effect of small interfering (si) RNA-mediated knockdown and plasmid-mediated overexpression of endoglin on fibroblast responsiveness to TGF-beta1 was assessed by examining smad phosphorylation, smad binding element (SBE) promoter activity, connective tissue growth factor (CTGF) expression and ability to contract collagen. RESULTS: Crohn\\'s stricture fibroblasts expressed increased constitutive cell-surface and whole-cell endoglin relative to control cells. Endoglin co-localized with filamentous actin. Fibroblasts treated with siRNA directed against endoglin exhibited enhanced TGF-beta1-mediated smad-3 phosphorylation, and collagen contraction. Cells transfected with an endoglin plasmid did not respond to TGF-beta1 by exhibiting SBE promoter activity or producing CTGF. CONCLUSION: Fibroblasts from strictures in CD express increased constitutive endoglin. Endoglin is a negative regulator of TGF-beta1 signalling in the intestinal fibroblast, modulating smad-3 phosphorylation, SBE promoter activity, CTGF production and collagen contraction.

  8. A novel Nrf2 activator from microbial transformation inhibits radiation-induced dermatitis in mice

    International Nuclear Information System (INIS)

    Nakagami, Yasuhiro; Masuda, Kayoko

    2016-01-01

    Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcriptional factor that regulates many antioxidants, and we have recently succeeded in obtaining a novel Nrf2 activator, RS9, from microbial transformation. RS9 is categorized as a triterpenoid, and well-known triterpenoids such as RTA 402 (bardoxolone methyl) and RTA 408 have been tested in clinical trials. RTA 408 lotion is currently being tested in patients at risk for radiation dermatitis. This prompted us to study the profiles of RS9 in the skin. All the above triterpenoids increased the level of an Nrf2-targeted gene, NADPH:quinone oxidoreductase-1, in normal human epidermal keratinocytes. Among them, the activity of RS9 was prominent; furthermore, the cellular toxicity was less compared with RTA compounds. BALB/c mice were irradiated with 30 Gy/day on Day 0, and compounds were topically applied on the back once daily from Day 1 to Day 30. Dermatitis scores peaked on Day 18, with a score of 2.6 in vehicle-treated mice, and topical applications of 0.1% RTA 402, RTA 408 and RS9 reduced the scores to 1.8, 2.0 and 1.4, respectively. Moreover, the percentage of animals with scores ≥2 was analyzed, and 0.1% RS9 suppressed the percentage from 100% to 47%. These results imply that RS9 has potential efficacy for treating radiation dermatitis.

  9. Positron lifetime studies of the hcp to fcc transformation induced by mechanical attrition of elemental titanium

    International Nuclear Information System (INIS)

    Manna, I.; Chattopadhyay, P.P.; Nandi, P.; Nambissan, P.M.G.

    2004-01-01

    Nanocrystallisation by planetary ball-milling of high purity elemental titanium (Ti) revealed a polymorphic transformation from its normal hexagonal close packed (hcp) structure to a face-centered cubic (fcc) phase. Positron lifetime measurements were carried out on samples collected after different hours of milling to characterize the defect structures at grain surfaces. With increasing hours of milling, the nanocrystalline grain size decreased and the positron lifetimes--one related to the annihilation at the grain surfaces and the other to that at the intergranular open volume domains--increased significantly due to the increased free volume at the trapping vacancy sites. However, between 5 to 10 hours of milling, the two lifetimes decreased before resuming increasing once again. This marked deviation from an otherwise expected continuous increase of positron lifetime coincided with structural rearrangement within the system bringing in an enhancement in the density of electrons. The repacking of atoms along the [0001] crystallographic direction could be a possibility for this observation. Positron radiation effects on the migration and agglomeration of nanoparticles are also discussed

  10. Visible Light Induced Green Transformation of Primary Amines to Imines Using a Silicate Supported Anatase Photocatalyst

    Directory of Open Access Journals (Sweden)

    Sifani Zavahir

    2015-01-01

    Full Text Available Catalytic oxidation of amine to imine is of intense present interest since imines are important intermediates for the synthesis of fine chemicals, pharmaceuticals, and agricultural chemicals. However, considerable efforts have been made to develop efficient methods for the oxidation of secondary amines to imines, while little attention has until recently been given to the oxidation of primary amines, presumably owing to the high reactivity of generated imines of primary amines that are easily dehydrogenated to nitriles. Herein, we report the oxidative coupling of a series of primary benzylic amines into corresponding imines with dioxygen as the benign oxidant over composite catalysts of TiO2 (anatase-silicate under visible light irradiation of λ > 460 nm. Visible light response of this system is believed to be as a result of high population of defects and contacts between silicate and anatase crystals in the composite and the strong interaction between benzylic amine and the catalyst. It is found that tuning the intensity and wavelength of the light irradiation and the reaction temperature can remarkably enhance the reaction activity. Water can also act as a green medium for the reaction with an excellent selectivity. This report contributes to the use of readily synthesized, environmentally benign, TiO2 based composite photocatalyst and solar energy to realize the transformation of primary amines to imine compounds.

  11. Visible light induced green transformation of primary amines to imines using a silicate supported anatase photocatalyst.

    Science.gov (United States)

    Zavahir, Sifani; Zhu, Huaiyong

    2015-01-26

    Catalytic oxidation of amine to imine is of intense present interest since imines are important intermediates for the synthesis of fine chemicals, pharmaceuticals, and agricultural chemicals. However, considerable efforts have been made to develop efficient methods for the oxidation of secondary amines to imines, while little attention has until recently been given to the oxidation of primary amines, presumably owing to the high reactivity of generated imines of primary amines that are easily dehydrogenated to nitriles. Herein, we report the oxidative coupling of a series of primary benzylic amines into corresponding imines with dioxygen as the benign oxidant over composite catalysts of TiO2 (anatase)-silicate under visible light irradiation of λ > 460 nm. Visible light response of this system is believed to be as a result of high population of defects and contacts between silicate and anatase crystals in the composite and the strong interaction between benzylic amine and the catalyst. It is found that tuning the intensity and wavelength of the light irradiation and the reaction temperature can remarkably enhance the reaction activity. Water can also act as a green medium for the reaction with an excellent selectivity. This report contributes to the use of readily synthesized, environmentally benign, TiO2 based composite photocatalyst and solar energy to realize the transformation of primary amines to imine compounds.

  12. Ca2+ transport in plant cells and mechanisms of transformation of phytochrome-induced photosignals

    Science.gov (United States)

    Volotovski, Igor D.

    1995-01-01

    The recent data on the influence of phytochrome on the efficiency of Ca2+ translocation across the membranes of oat protoplasts are given. Ca2+ uptake in the protoplasts was shown to be influenced by the red light (R) illumination. This effect was reverted by the following far-red light (FR) illumination. To elucidate the sensitivity to phytochrome-controlling action the screening between the mechanisms of Ca2+ transport across the plasma membranes of oat protoplasts, Na+/Ca2+ and Ca2+/H+ exchangers, Ca2+-pump and Ca2+-channel was done. It was established that phytochrome modulated the activity of Na+/Ca2+-exchanger and Ca2+-pump. The light-mediated oscillations of cytoplasmic Ca2+ concentration in the oat protoplasts were demonstrated using fluorescence probe quin2 loaded into the cells and laser monitoring of fluorescence signal. The evidences were obtained that the oscillations were not the result of the elevation of cytoplasmic Ca2+ concentration and had no connection with Ca2+ pool of mitochondria. The possibility of the relation between the Ca2+ oscillations and phosphoinositide metabolism in plant cell membranes is analyzed. The mechanisms of transformation of primary phytochrome signal into biological effects were discussed.

  13. Inspection of arterial-induced skin vibration by Moire fringe with two-dimensional continuous wavelet transform

    Science.gov (United States)

    Wang, Chun-Hsiung; Chiu, Shih-Yung; Hsu, Yu-Hsiang; Lee, Shu-Sheng; Lee, Chih-Kung

    2017-06-01

    A non-contact arterial-induced skin vibration inspection system is implemented. This optical metrology system is constructed with shadow Moiré configuration and the fringe analysis algorithm. Developed with the Region of Interested (ROI) capturing technique and the Two-dimensional Wavelet Transform (2D-CWT) method, this algorithm is able to retrieve the height-correlated phase information from the shadow Moiré fringe patterns. Using a commercial video camera or a CMOS image sensor, this system could monitor the skin-vibration induced by the cyclic deformation of inner layered artery. The cross-sectional variation and the rhythm of heart cycle could be continuously measured for health monitoring purposes. The average vibration amplitude of the artery at the wrist ranges between 20 μm and 50 μm, which is quite subtle comparing with the skin surface structure. Having the non-stationary motion of human body, the traditional phase shifting (PS) technique can be very unstable due to the requirement of several frames of images, especially for case that artery is continuously pumping. To bypass this fundamental issue, the shadow Moiré technique is introduced to enhance the surface deformation characteristic. And the phase information is retrieved by the means of spectrum filtering instead of PS technique, which the phase is calculated from intensity maps of multiple images. The instantaneous surface can therefore be reconstructed individually from each frame, enabling the subtle arterial-induced skin vibration measurement. The comparative results of phase reconstruction between different fringe analysis algorithms will be demonstrated numerically and experimentally. And the electrocardiography (ECG) results will used as the reference for the validity of health monitoring potential of the non-contact arterial-induced skin vibration inspection system.

  14. Energetic approach for ductile tearing; Approche energetique de la dechirure ductile

    Energy Technology Data Exchange (ETDEWEB)

    Marie, St

    1999-07-01

    This study focuses on ductile crack initiation and propagation. It aims to propose an approach for the engineer allowing the prediction of the evolution of cracks in large scale components, from parameters determined on laboratory specimens. A crack initiation criterion, defining a J{sub i} tenacity related to crack tip blunting proposed in the literature is validated in the study. This criterion is shown to be transferable from laboratory specimens to structures. The literature review shows that an approach based on the dissipated energy in the fracture process during propagation offers an economical and simple solution to simulate large crack growth. A numerical method is proposed to estimate this fracture energy. The existence of an energy parameter G{sub fr} is shown, by simulating the propagation by the simultaneous release of several elements and by the use of the Rice integral with an original integration path. This parameter represents the needed energy for a unit crack extension and appears to be intrinsic to the material. A global energy statement allows to relate this parameter to a variation of the plastic part of J integral. It offers a second numerical method to simulate the propagation just from stationary numerical calculations, as well as the elaboration of a simplified method. This approach, using two parameters J{sub i} and G{sub fr}, intrinsic to the material and experimentally measurable on specimens, is validated on many tests such as crack pipes subjected to four points bending and cracked rings in compression. For example, this approach allows to model up to 90 mm ductile tearing in a pipe with a circumferential through-wall crack in ferritic steel, or to anticipate the evolution of a semi-elliptical crack in an aged austenitic ferritic steel plate subjected to bending. (author)

  15. Involvement of p53 Mutation and Mismatch Repair Proteins Dysregulation in NNK-Induced Malignant Transformation of Human Bronchial Epithelial Cells

    Directory of Open Access Journals (Sweden)

    Ying Shen

    2014-01-01

    Full Text Available Genome integrity is essential for normal cellular functions and cell survival. Its instability can cause genetic aberrations and is considered as a hallmark of most cancers. To investigate the carcinogenesis process induced by tobacco-specific carcinogen NNK, we studied the dynamic changes of two important protectors of genome integrity, p53 and MMR system, in malignant transformation of human bronchial epithelial cells after NNK exposure. Our results showed that the expression of MLH1, one of the important MMR proteins, was decreased early and maintained the downregulation during the transformation in a histone modification involved and DNA methylation-independent manner. Another MMR protein PMS2 also displayed a declined expression while being in a later stage of transformation. Moreover, we conducted p53 mutation analysis and revealed a mutation at codon 273 which led to the replacement of arginine by histidine. With the mutation, DNA damage-induced activation of p53 was significantly impaired. We further reintroduced the wild-type p53 into the transformed cells, and the malignant proliferation can be abrogated by inducing cell cycle arrest and apoptosis. These findings indicate that p53 and MMR system play an important role in the initiation and progression of NNK-induced transformation, and p53 could be a potential therapeutic target for tobacco-related cancers.

  16. Numerical modeling of ductile tearing effects on cleavage fracture toughness

    International Nuclear Information System (INIS)

    Dodds, R.H. Jr.; Tang, M.; Anderson, T.L.

    1994-05-01

    Experimental studies demonstrate a significant effect of specimen size, a/W ratio and prior ductile tearing on cleavage fracture toughness values (J c ) measured in the ductile-to-brittle transition region of ferritic materials. In the lower-transition region, cleavage fracture often occurs under conditions of large-scale yielding but without prior ductile crack extension. The increased toughness develops when plastic zones formed at the crack tip interact with nearby specimen surfaces which relaxes crack-tip constraint (stress triaxiality). In the mid-to-upper transition region, small amounts of ductile crack extension (often c -values. Previous work by the authors described a micromechanics fracture model to correct measured J c -values for the mechanistic effects of large-scale yielding. This new work extends the model to also include the influence of ductile crack extension prior to cleavage. The paper explores development of the new model, provides necessary graphs and procedures for its application and demonstrates the effects of the model on fracture data sets for two pressure vessel steels (A533B and A515)

  17. Ductile electroactive biodegradable hyperbranched polylactide copolymers enhancing myoblast differentiation.

    Science.gov (United States)

    Xie, Meihua; Wang, Ling; Guo, Baolin; Wang, Zhong; Chen, Y Eugene; Ma, Peter X

    2015-12-01

    Myotube formation is crucial to restoring muscular functions, and biomaterials that enhance the myoblast differentiation into myotubes are highly desirable for muscular repair. Here, we report the synthesis of electroactive, ductile, and degradable copolymers and their application in enhancing the differentiation of myoblasts to myotubes. A hyperbranched ductile polylactide (HPLA) was synthesized and then copolymerized with aniline tetramer (AT) to produce a series of electroactive, ductile and degradable copolymers (HPLAAT). The HPLA and HPLAAT showed excellent ductility with strain to failure from 158.9% to 42.7% and modulus from 265.2 to 758.2 MPa. The high electroactivity of the HPLAAT was confirmed by UV spectrometer and cyclic voltammogram measurements. These HPLAAT polymers also showed improved thermal stability and controlled biodegradation rate compared to HPLA. Importantly, when applying these polymers for myotube formation, the HPLAAT significantly improved the proliferation of C2C12 myoblasts in vitro compared to HPLA. Furthermore, these polymers greatly promoted myogenic differentiation of C2C12 cells as measured by quantitative analysis of myotube number, length, diameter, maturation index, and gene expression of MyoD and TNNT. Together, our study shows that these electroactive, ductile and degradable HPLAAT copolymers represent significantly improved biomaterials for muscle tissue engineering compared to HPLA. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Impact of ductility on hydraulic fracturing in shales

    Science.gov (United States)

    MacMinn, Chris; Auton, Lucy

    2016-04-01

    Hydraulic fracturing is a method for extracting natural gas and oil from low-permeability rocks such as shale via the high-pressure injection of fluid into the bulk of the rock. The goal is to initiate and propagate fractures that will provide hydraulic access deeper into the reservoir, enabling gas or oil to be collected from a larger region of the rock. Fracture is the tensile failure of a brittle material upon reaching a threshold tensile stress, but some shales have a high clay content and may yield plastically before fracturing. Plastic deformation is the shear failure of a ductile material, during which stress relaxes through irreversible rearrangements of the particles of the material. Here, we investigate the impact of the ductility of shales on hydraulic fracturing. We first consider a simple, axisymmetric model for radially outward fluid injection from a wellbore into a ductile porous rock. We use this model to show that plastic deformation greatly reduces the maximum tensile stress, and that this maximum stress does not always occur at the wellbore. We then complement these results with laboratory experiments in an analogue system, and with numerical simulations based on the discrete element method (DEM), both of which suggest that ductile failure can indeed dramatically change the resulting deformation pattern. These results imply that hydraulic fracturing may fail in ductile rocks, or that the required injection rate for fracking may be much larger than the rate predicted from models that assume purely elastic mechanical behavior.

  19. Revealing the extra-high ductility and toughness of micro+duplex medium+Mn steel in a large temperature range from 200 ℃ to -196 ℃

    DEFF Research Database (Denmark)

    Cao, Wenquan; Hu, Jun; Dong, Han

    2014-01-01

    A medium-Mn steel (0.2C5Mn) was processed by intercritical annealing at different temperature (625℃ and 650℃) after forging and hot rolling. The microstructures were characterized by transmission electron microscopy and the mechanical properties were measured by tensile tests and impact tests...... at different temperatures. It was found that an ultrafine grained micro-duplex structure existed with austenite and ferrite laths formed by means of an austenite reverse transformation during intercritical annealing (shortly called ART-annealing). Ultrahigh ductility (total elongation larger than 30%) could...... be obtained in the temperature range from 200℃ to -196℃. And significantly delayed transition from ductile to brittle and no less than 200J impact toughness at -40℃ could be obtained in the ART-annealed medium-Mn steel. Based on the analysis of microstructure and mechanical properties, the enhanced ductility...

  20. Microstructure feature of friction stir butt-welded ferritic ductile iron

    International Nuclear Information System (INIS)

    Chang, Hung-Tu; Wang, Chaur-Jeng; Cheng, Chin-Pao

    2014-01-01

    Highlights: • Defect-free ferritic ductile iron joints is fabricated by FSW. • The welding nugget is composed of graphite, martensite, and recrystallized ferrite. • The graphite displays a striped pattern in the surface and advancing side. • The ferritic matrix transforms into martensite structure during welding. • High degree of plastic deformation is found on the advancing side. - Abstract: This study conducted friction stir welding (FSW) by using the butt welding process to join ferritic ductile iron plates and investigated the variations of microsturcture in the joined region formed after welding. No defects appeared in the resulting experimental weld, which was formed using a 3-mm thick ductile iron plate and tungsten carbide alloy stir rod to conduct FSW at a rotational speed of 982 rpm and traveling speed of 72 mm/min. The welding region was composed of deformed graphite, martensite phase, and dynamically recrystallized ferrite structures. In the surface region and on the advancing side (AS), the graphite displayed a striped configuration and the ferritic matrix transformed into martensite. On the retreating side (RS), the graphite surrounded by martensite remained as individual granules and the matrix primarily comprised dynamically recrystallized ferrite. After welding, diffusion increased the carbon content of the austenite around the deformed graphite nodules, which transformed into martensite during the subsequent cooling process. A micro Vickers hardness test showed that the maximum hardness value of the martensite structures in the weld was approximately 800 HV. An analysis using an electron probe X-ray microanalyzer (EPMA) indicated that its carbon content was approximately 0.7–1.4%. The peak temperature on the RS, 8 mm from the center of the weld, measured 630 °C by the thermocouple. Overall, increased severity of plastic deformation and process temperature near the upper stir zone (SZ) resulted in distinct phase transformation

  1. Simultaneously enhanced strength and ductility for 3D-printed stainless steel 316L by selective laser melting

    Science.gov (United States)

    Sun, Zhongji; Tan, Xipeng; Tor, Shu Beng; Chua, Chee Kai

    2018-04-01

    Laser-based powder-bed fusion additive manufacturing or three-dimensional printing technology has gained tremendous attention due to its controllable, digital, and automated manufacturing process, which can afford a refined microstructure and superior strength. However, it is a major challenge to additively manufacture metal parts with satisfactory ductility and toughness. Here we report a novel selective laser melting process to simultaneously enhance the strength and ductility of stainless steel 316L by in-process engineering its microstructure into a crystallographic texture. We find that the tensile strength and ductility of SLM-built stainless steel 316L samples could be enhanced by 16% and 40% respectively, with the engineered textured microstructure compared to the common textured microstructure. This is because the favorable nano-twinning mechanism was significantly more activated in the textured stainless steel 316L samples during plastic deformation. In addition, kinetic simulations were performed to unveil the relationship between the melt pool geometry and crystallographic texture. The new additive manufacturing strategy of engineering the crystallographic texture can be applied to other metals and alloys with twinning-induced plasticity. This work paves the way to additively manufacture metal parts with high strength and high ductility.

  2. Alteration hydrothermale et deformation ductile des roches volcaniques acides associees au gisement sulfure de draa sfar (Jebilet Centrales, Maroc

    Directory of Open Access Journals (Sweden)

    Zinbi, Y.

    2005-12-01

    Full Text Available The volcanics and volcanoclastic rocks of Draa Sfar (Central Jebilet, Moroccan hercynian belt are affected by ductile stress and hydrothermal alteration accompanied by a weak degree of metamorphism (greenschist facies. Some N-S oriented shearing zones, affect locally these formations while being the site of an important hydrothermal activity. The consequences of these transformations from a non to slightly- deformed rhyodacite, show that through these ductile shearing zones: (1 the mineralogical assemblage of hydrothermal alteration is essentially formed by chlorite, sericite, quartz and magnetite; (2 the gradual increase of the alteration indexes is accompanied by the destruction of the phenocrists and the recrystallization of the matrix by phyllosilicates and quartz; (3 the progressive transfer of material is more intense in the more deformed zones where the values of Ti, Al and Zr remain constant. These shearing zones played a very important role in the circulation of fluids and the transformation of the rhyodacite of Draa Sfar.Les roches volcaniques et volcanoclastiques de Draa Sfar (Jebilet centrales, Maroc hercynien sont affectées par une déformation ductile accompagnée d’un métamorphisme de faible degré (faciès schistes verts et d’une altération hydrothermale. Des zones de cisaillement de direction N-S, ont affecté localement ces formations tout en étant vecteurs d’une importante activité hydrothermale. Le suivi de ces transformations à partir de la rhyodacite non ou peu déformée, montre qu’à travers ces zones de cisaillements ductiles : (1 l’assemblage minéralogique d’altération hydrothermale est formé essentiellement de chlorite, de séricite, de quartz et de magnétite ; (2 l’augmentation graduelle des indices d’altération s’exprime par la destruction des phénocristaux au profit d’une matrice recristallisée en phyllosilicates et quartz ; (3 le transfert progressif de la matière est plus intense

  3. Transformation of bone marrow stem-cells and radiation-induced myeloid leukemia in mice

    International Nuclear Information System (INIS)

    Hirashima, K.; Bessho, M.; Hayata, I.; Nara, N.; Kawase, Y.; Ohtani, M.

    1982-01-01

    After a single whole-body X-irradiation of 300R to male RFM/MsNrs strain mice, the occurrence of myeloid leukemia initiated since four months and ceased at eleven months after irradiation. The cumulative incidence reached 24.5%. A time course study on the kinetics of pluripotential stem-cells (CFU-S) and granuloid committed stem-cells (CFU-C) in the marrow after 300R was also performed. The repopulation of CFU-S was accomplished within one month whereas that of CFU-C needed 210 days after irradiation. The incidence of leukemia was very rare after the complete repopulation of CFU-C. Simultaneously, collected spleen cells from the irradiated mice without overt leukemia were transplanted into 300-600R irradiated recipients of another sex. Three months thereafter, recipients were sacrificed to detect leukemic changes and the origin of leukemic cells by chromosome analysis. The results revealed that leukemic cell transformation of donor cells began 18 days after irradiation and on an average, 37.1% of the irradiated mice carried potentially leukemic cells for seven months after exposure, whereas none of the unirradiated mice carried leukemic cells at 7 months after irradiation. To investigate host factor(s) contributing to the proliferation of leukemic cells, the suppression of cellular immunity after 300R was measured by GVH mortality assay. However, the recovery of cellular immunity was observed until three months after irradiation and the role of cellular immunity to proliferation of leukemic cells after three months was negligible. (author)

  4. Photo-induced transformations of mercury(II) species in the presence of algae, Chlorella vulgaris

    Energy Technology Data Exchange (ETDEWEB)

    Deng Lin, E-mail: dlwhu@163.com [Department of Municipal Engineering, Southeast University, Nanjing 210096 (China); Fu Dafang [Department of Municipal Engineering, Southeast University, Nanjing 210096 (China); Deng Nansheng [School of Resources and Environmental Science, Wuhan University, Wuhan 430072 (China)

    2009-05-30

    The effects of algae (i.e., Chlorella vulgaris), Fe(III), humic substances, and pH on the photoreduction of Hg(II) under the irradiation of metal halide lamps ({lambda} {>=} 365 nm, 250 W) were investigated in this paper. The photoreduction rate of Hg(II) was found to increase with the increasing concentration of algae, Fe(III), and humic substances. The cooperation action of Fe(III) and humic substances accelerated the photoreduction of Hg(II). When the initial concentration of Hg(II) was in the range of 0.0-200.0 {mu}g L{sup -1} with initial algae concentrations 7.0 x 10{sup 9} cells L{sup -1} at pH 7.0, the initial photoreduction rate of Hg(II) could be expressed by the equation: -dC{sub Hg(II)}/dt = 0.65 x [C{sub Hg(II)}]{sup 0.39} with a correlation coefficient of R = 0.9912. The study on the photochemical process in terms of total mercury mass balance revealed that more than 40.86% of Hg(II) from the algal suspension was reduced to volatile metallic mercury. This paper discussed the photoreduction mechanism of Hg(II) in the presence of algae. This research will provide information for predicting the photoreduction of Hg(II) in the real environment. It will be helpful for understanding the photochemical transformation of Hg(II) and the formation of DGM in natural water in the presence of algae complexes. It will also be helpful for providing new methods to deal with heavy metal pollution.

  5. Photo-induced transformations of mercury(II) species in the presence of algae, Chlorella vulgaris

    International Nuclear Information System (INIS)

    Deng Lin; Fu Dafang; Deng Nansheng

    2009-01-01

    The effects of algae (i.e., Chlorella vulgaris), Fe(III), humic substances, and pH on the photoreduction of Hg(II) under the irradiation of metal halide lamps (λ ≥ 365 nm, 250 W) were investigated in this paper. The photoreduction rate of Hg(II) was found to increase with the increasing concentration of algae, Fe(III), and humic substances. The cooperation action of Fe(III) and humic substances accelerated the photoreduction of Hg(II). When the initial concentration of Hg(II) was in the range of 0.0-200.0 μg L -1 with initial algae concentrations 7.0 x 10 9 cells L -1 at pH 7.0, the initial photoreduction rate of Hg(II) could be expressed by the equation: -dC Hg(II) /dt = 0.65 x [C Hg(II) ] 0.39 with a correlation coefficient of R = 0.9912. The study on the photochemical process in terms of total mercury mass balance revealed that more than 40.86% of Hg(II) from the algal suspension was reduced to volatile metallic mercury. This paper discussed the photoreduction mechanism of Hg(II) in the presence of algae. This research will provide information for predicting the photoreduction of Hg(II) in the real environment. It will be helpful for understanding the photochemical transformation of Hg(II) and the formation of DGM in natural water in the presence of algae complexes. It will also be helpful for providing new methods to deal with heavy metal pollution.

  6. Surface modification induced phase transformation and structure variation on the rapidly solidified recast layer of titanium

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Ming-Hung [Department of Mechanical Engineering and Graduate Institute of Mechanical and Precision Engineering, National Kaoshiung University of Applied Sciences, Kaoshiung 807, Taiwan (China); School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Haung, Chiung-Fang [School of Dental Technology, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Division of Family and Operative Dentistry, Department of Dentistry, Taipei Medical University Hospital, Taipei 110, Taiwan (China); Research Center for Biomedical Devices and Prototyping Production, Taipei Medical University, Taipei 110, Taiwan (China); Shyu, Shih-Shiun [Department of Dentistry, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei City 231, Taiwan (China); Chou, Yen-Ru [Research Center for Biomedical Devices and Prototyping Production, Taipei Medical University, Taipei 110, Taiwan (China); Graduate Institute of Biomedical Materials and Tissue Engineering, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Research Center for Biomedical Implants and Microsurgery Devices, Taipei Medical University, Taipei 110, Taiwan (China); Lin, Ming-Hong [Department of Mechanical Engineering and Graduate Institute of Mechanical and Precision Engineering, National Kaoshiung University of Applied Sciences, Kaoshiung 807, Taiwan (China); Peng, Pei-Wen, E-mail: apon@tmu.edu.tw [School of Dental Technology, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); and others

    2015-08-15

    In this study, neodymium-doped yttrium orthovanadate (Nd:YVO{sub 4}) as a laser source with different scanning speeds was used on biomedical Ti surface. The microstructural and biological properties of laser-modified samples were investigated by means of optical microscope, electron microscope, X-ray diffraction, surface roughness instrument, contact angle and cell cytotoxicity assay. After laser modification, the rough volcano-like recast layer with micro-/nanoporous structure and wave-like recast layer with nanoporous structure were generated on the surfaces of laser-modified samples, respectively. It was also found out that, an α → (α + rutile-TiO{sub 2}) phase transition occurred on the recast layers of laser-modified samples. The Ti surface becomes hydrophilic at a high speed laser scanning. Moreover, the cell cytotoxicity assay demonstrated that laser-modified samples did not influence the cell adhesion and proliferation behaviors of osteoblast (MG-63) cell. The laser with 50 mm/s scanning speed induced formation of rough volcano-like recast layer accompanied with micro-/nanoporous structure, which can promote cell adhesion and proliferation of MG-63 cell on Ti surface. The results indicated that the laser treatment was a potential technology to enhance the biocompatibility for titanium. - Highlights: • Laser induced the formation of recast layer with micro-/nanoporous structure on Ti. • An α → (α + rutile-TiO{sub 2}) phase transition was observed within the recast layer. • The Ti surface becomes hydrophilic at a high speed laser scanning. • Laser-modified samples exhibit good biocompatibility to osteoblast (MG-63) cell.

  7. Effect of Tin, Copper and Boron on the Hot Ductility of 20CrMnTi Steel between 650 °C and 1100 °C

    Science.gov (United States)

    Peng, Hong-bing; Chen, Wei-qing; Chen, Lie; Guo, Dong

    2015-02-01

    The hot ductility of 20CrMnTi steel with x% tin, y% copper and z ppm boron (x = 0, 0.02; y = 0, 0.2; z = 0, 60) was investigated. The results show that tin and copper in 20CrMnTi steel are detrimental to its hot ductility while adding boron can eliminate the adverse effect and enhance hot ductility greatly. Tin is found to segregate to the boundaries tested by EPMA in 20CrMnTi steel containing tin and copper and tin-segregation is suppressed by adding boron, moreover, copper was found not to segregate to boundaries, however, fine copper sulfide was found from carbon extraction replicas using TEM. The adverse effect of tin and copper on the hot ductility was due mainly to tin segregation and fine copper sulfide in the steel. The proeutectoid ferrite film precipitating along the austenite grain boundary causes the ductility trough of the three examined steels. Tin and copper in 20CrMnTi steel can retard the occurrence of dynamic recrystallization (DRX) while boron-addition can compensate for that change. The beneficial effect of boron on 20CrMnTi steel containing tin and copper might be ascribed to the fact that boron segregates to grain boundaries, accelerates onset of DRX, retards austenite/ferrite transformation and promotes intragranular nucleation of ferrite.

  8. Suppression of transformed foci, induced by alpha radiation of C3H 10T1/2 cells, by untransformed cells

    International Nuclear Information System (INIS)

    Lloyd, E.L.; Gemmell, M.A.; Henning, C.B.

    1978-01-01

    The C3H 10T1/2 CL8 cell line obtained from a mouse embryo has been widely used for screening chemical carcinogens. Transformed foci are easily distinguishable in this system as crisscrossed, piled-up cells which stain more deeply than the surrounding untransformed cells. When these foci are ringcloned and subcultured, they have been shown to give rise to malignant tumors in C3H immunodepressed mice. Previous work showed that such malignant transformations, which occurred with a dose dependent frequency, could be induced by alpha particle irradiation. The present study, in turn, demonstrates that the expression of these transformations can be completely suppressed by co-cultivating the transformed cells with a large number of untransformed cells. The precise ratio of the number of untransformed cells to transformed cells to give complete suppression was found to vary in different experiments. Maximum effects were seen when a small number of transformed cells in low passage were used. These experiments may provide at least a partial explanation for the greatly increased frequency of transformations per cell irradiated in vitro, compared with the number of tumors observed after irradiation of the same number of cells in vivo. In addition, if conditions could be optimized whereby transformed foci could reproducibly be eliminated by the use of a known number of untransformed cells, this might have important applications in the prevention and treatment of certain human cancers

  9. Expression of transforming growth factor alpha and epidermal growth factor receptor in rat lung neoplasms induced by plutonium-239

    International Nuclear Information System (INIS)

    Stegelmeier, B.L.; Gillett, N.A.; Hahn, F.F.; Kelly, G.; Rebar, A.H.

    1994-01-01

    Ninety-two rat lung proliferative lesions and neoplasms induced by inhaled 239 PuO 2 were evaluated for aberrant expression of transforming growth factor alpha (TGF-α) and epidermal growth factor receptor (EGFR). Expression of TGF-α protein, measured by immunohistochemistry, was higher in 94% of the squamous cell carcinomas and 87% of the foci of alveolar epithelial squamous metaplasia than that exhibited by the normal-appearing, adjacent lung parenchyma. In contrast, only 20% of adenocarcinomas and foci of epithelial hyperplasia expressed elevated levels of TGF-α. Many neoplasms expressing TGF-α also expressed excessive levels of EGFR mRNA. Southern and DNA slot blot analyses showed that the elevated EGFR expression was not due to amplification of the EGFR gene. These data suggest that increased amounts of TGF-α were early alterations in the progression of plutonium-induced squamous cell carcinoma, and these increases may occur in parallel with overexpression of the receptor for this growth factor. Together, these alterations create a potential autocrine loop for sustaining clonal expansion of cells initiated by high-LET radiation. 44 refs., 4 figs., 1 tab

  10. Chondroitin sulfate microparticles modulate transforming growth factor-β1-induced chondrogenesis of human mesenchymal stem cell spheroids.

    Science.gov (United States)

    Goude, Melissa C; McDevitt, Todd C; Temenoff, Johnna S

    2014-01-01

    Mesenchymal stem cells (MSCs) have been previously explored as a part of cell-based therapies for the repair of damaged cartilage. Current MSC chondrogenic differentiation strategies employ large pellets; however, we have developed a technique to form small MSC aggregates (500-1,000 cells) that can reduce transport barriers while maintaining a multicellular structure analogous to cartilaginous condensations. The objective of this study was to examine the effects of incorporating chondroitin sulfate methacrylate (CSMA) microparticles (MPs) within small MSC spheroids cultured in the presence of transforming growth factor (TGF)-β1 on chondrogenesis. Spheroids with MPs induced earlier increases in collagen II and aggrecan gene expression (chondrogenic markers) than spheroids without MPs, although no large differences in immunostaining for these matrix molecules were observed by day 21 between these groups. Collagen I and X were also detected in the extracellular matrix (ECM) of all spheroids by immunostaining. Interestingly, histology revealed that CSMA MPs clustered together near the center of the MSC spheroids and induced circumferential alignment of cells and ECM around the material core. This study demonstrates the use of CSMA materials to further examine the effects of matrix molecules on MSC phenotype as well as potentially direct differentiation in a more spatially controlled manner that better mimics the architecture of specific musculoskeletal tissues. © 2014 S. Karger AG, Basel.

  11. Destruction-polymerization transformations as a source of radiation-induced extended defects in chalcogenide glassy semiconductors

    International Nuclear Information System (INIS)

    Shpotyuk, Oleh; Filipecki, Jacek; Shpotyuk, Mykhaylo

    2013-01-01

    Long-wave shift of the optical transmission spectrum in the region of fundamental optical absorption edge is registered for As 2 S 3 chalcogenide glassy semiconductors after γ-irradiation. This effect is explained in the frameworks of the destruction-polymerization transformations concept by accepting the switching of the heteropolar As-S covalent bonds into homopolar As-As ones. It is assumed that (As 4 + ; S 1 - ) defect pairs are created under such switching. Formula to calculate content of the induced defects in chalcogenide glassy semiconductors is proposed. It is assumed that defects concentration depends on energy of broken covalent bond, bond-switching energy balance, correlation energy, optical band-gap and energy of excitation light. It is shown that theoretically calculated maximally possible content of radiation-induced defects in As 2 S 3 is about 1.6% while concentration of native defects is negligible. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. The γ-ε martensitic transformation: a model for stress induced variant and its interaction with grain boundary

    International Nuclear Information System (INIS)

    Guenin, G.

    1995-01-01

    The γ (f.c.c.) to ε (h.c.p.) martensitic transformation occurs through the Shockley a/6 left angle 211 right angle faulting every second {111} plane of the f.c.c. structure. A stress induced thin single variant corresponds to a single a/6 left angle 211 right angle faulting vector and leads to a large homogeneous shear (0.35) in amplitude. The tip of such a plate is composed of a set of identical Shockley partial dislocations with large mutual interactions. This work is a presentation of a model which describes the martensite morphology of stress induced ε martensite in shape memory Fe-Mn-Si based alloys. The model includes the formation mechanism of the plate (Seeger's like) and its growth inside a limited grain. The mutual interaction of Shockley dislocations and their interaction with the grain boundary is semi quantitatively described; it leads to a lenticular shape of ε martensite thin plates. The model is able to explain the behaviour of this kind of alloys concerning the superelastic effect and the shape memory. (orig.)

  13. Malignant transformation of human fibroblasts by neutrons and by gamma radiation: Relationship of mutations induced. Final report, January 1, 1993--December 31, 1995

    International Nuclear Information System (INIS)

    McCormick, J.J.

    1997-01-01

    The overall purpose of this project was to compare on a quantitative basis, the transforming and mutagenic effect of ionizing radiation ( 60 Co) and neutron radiation on human fibroblasts irradiated at different phases of the cell cycle. These studies were undertaken since mouse fibroblasts (C3H10T1/2) exhibit a window of sensitivity to ionizing radiation-induced transformation in late G2 and perhaps M and to neutron-induced transformation in G1 and in G2. In the 10T1/2 cells, essentially all the induced transformants come from cells that are in the sensitive windows at the time of irradiation. The mechanism responsible for the sensitive windows in the 10T1/2 cells has not yet been elucidated. Because of the aneuploid nature of 10T1/2 cells and the fact that mouse chromosomes are very small and nearly identical in size, some types of experiments that might indicate the mechanism are nearly impossible to carry out in these cells. Regardless of the mechanism, the fact that transformation results from a select subpopulation of cells has important practical implications for persons exposed to radiation. Whether a similar phenomena exists with other DNA damaging agents is not clear. Until this time, there has not been a human cell transformation assay that will allow one to quantitatively compare the transforming ability of radiation with different qualities. The MSU-1.1 cells had the potential to give such an assay. The authors developed this assay demonstrating a dose response and carrying out an extensive characterization of the focus-derived transformed cells including assays for tumorigenicity

  14. Continuous activation of Nrf2 and its target antioxidant enzymes leads to arsenite-induced malignant transformation of human bronchial epithelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xu [Department of Toxicology, School of Public Health, Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, Medical College of Soochow University, Suzhou, Jiangsu (China); Wang, Dapeng [Department of Toxicology, School of Public Health, Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, Medical College of Soochow University, Suzhou, Jiangsu (China); Department of Toxicology, School of Public Health, Guizhou Medical University, Guiyang, Guizhou (China); Ma, Yuan; Xu, Xiguo; Zhu, Zhen; Wang, Xiaojuan; Deng, Hanyi; Li, Chunchun; Chen, Min; Tong, Jian [Department of Toxicology, School of Public Health, Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, Medical College of Soochow University, Suzhou, Jiangsu (China); Yamanaka, Kenzo [Laboratory of Environmental Toxicology and Carcinogenesis, School of Pharmacy, Nihon University, Chiba (Japan); An, Yan, E-mail: dranyan@126.com [Department of Toxicology, School of Public Health, Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, Medical College of Soochow University, Suzhou, Jiangsu (China)

    2015-12-01

    Long-term exposure to arsenite leads to human lung cancer, but the underlying mechanisms of carcinogenesis remain obscure. The transcription factor of nuclear factor-erythroid-2 p45-related factor (Nrf2)-mediated antioxidant response represents a critical cellular defense mechanism and protection against various diseases. Paradoxically, emerging data suggest that the constitutive activation of Nrf2 is associated with cancer development, progression and chemotherapy resistance. However, the role of Nrf2 in the occurrence of cancer induced by long-term arsenite exposure remains to be fully understood. By establishing transformed human bronchial epithelial (HBE) cells via chronic low-dose arsenite treatment, we showed that, in acquiring this malignant phenotype, continuous low level of ROS and sustained enhancement of Nrf2 and its target antioxidant enzyme levels were observed in the later-stage of arsenite-induced cell transformation. The downregulation of Keap1 level may be responsible for the over-activation of Nrf2 and its target enzymes. To validate these observations, Nrf2 was knocked down in arsenite-transformed HBE cells by SiRNA transfection, and the levels of Nrf2 and its target antioxidant enzymes, ROS, cell proliferation, migration, and colony formation were determined following these treatments. Results showed that blocked Nrf2 expression significantly reduced Nrf2 and its target antioxidant enzyme levels, restored ROS levels, and eventually suppressed cell proliferation, migration, and colony formation of the transformed cells. In summary, the results of the study strongly suggested that the continuous activation of Nrf2 and its target antioxidant enzymes led to the over-depletion of intracellular ROS levels, which contributed to arsenite-induced HBE cell transformation. - Highlights: • Low level, long term arsenite exposure induces malignant transformation in vitro. • Long term arsenite exposure reduces ROS and MDA levels. • Long term arsenite

  15. Continuous activation of Nrf2 and its target antioxidant enzymes leads to arsenite-induced malignant transformation of human bronchial epithelial cells

    International Nuclear Information System (INIS)

    Yang, Xu; Wang, Dapeng; Ma, Yuan; Xu, Xiguo; Zhu, Zhen; Wang, Xiaojuan; Deng, Hanyi; Li, Chunchun; Chen, Min; Tong, Jian; Yamanaka, Kenzo; An, Yan

    2015-01-01

    Long-term exposure to arsenite leads to human lung cancer, but the underlying mechanisms of carcinogenesis remain obscure. The transcription factor of nuclear factor-erythroid-2 p45-related factor (Nrf2)-mediated antioxidant response represents a critical cellular defense mechanism and protection against various diseases. Paradoxically, emerging data suggest that the constitutive activation of Nrf2 is associated with cancer development, progression and chemotherapy resistance. However, the role of Nrf2 in the occurrence of cancer induced by long-term arsenite exposure remains to be fully understood. By establishing transformed human bronchial epithelial (HBE) cells via chronic low-dose arsenite treatment, we showed that, in acquiring this malignant phenotype, continuous low level of ROS and sustained enhancement of Nrf2 and its target antioxidant enzyme levels were observed in the later-stage of arsenite-induced cell transformation. The downregulation of Keap1 level may be responsible for the over-activation of Nrf2 and its target enzymes. To validate these observations, Nrf2 was knocked down in arsenite-transformed HBE cells by SiRNA transfection, and the levels of Nrf2 and its target antioxidant enzymes, ROS, cell proliferation, migration, and colony formation were determined following these treatments. Results showed that blocked Nrf2 expression significantly reduced Nrf2 and its target antioxidant enzyme levels, restored ROS levels, and eventually suppressed cell proliferation, migration, and colony formation of the transformed cells. In summary, the results of the study strongly suggested that the continuous activation of Nrf2 and its target antioxidant enzymes led to the over-depletion of intracellular ROS levels, which contributed to arsenite-induced HBE cell transformation. - Highlights: • Low level, long term arsenite exposure induces malignant transformation in vitro. • Long term arsenite exposure reduces ROS and MDA levels. • Long term arsenite

  16. Brittle and ductile friction and the physics of tectonic tremor

    Science.gov (United States)

    Daub, Eric G.; Shelly, David R.; Guyer, Robert A.; Johnson, P.A.

    2011-01-01

    Observations of nonvolcanic tremor provide a unique window into the mechanisms of deformation and failure in the lower crust. At increasing depths, rock deformation gradually transitions from brittle, where earthquakes occur, to ductile, with tremor occurring in the transitional region. The physics of deformation in the transition region remain poorly constrained, limiting our basic understanding of tremor and its relation to earthquakes. We combine field and laboratory observations with a physical friction model comprised of brittle and ductile components, and use the model to provide constraints on the friction and stress state in the lower crust. A phase diagram is constructed that characterizes under what conditions all faulting behaviors occur, including earthquakes, tremor, silent transient slip, and steady sliding. Our results show that tremor occurs over a range of ductile and brittle frictional strengths, and advances our understanding of the physical conditions at which tremor and earthquakes take place.

  17. Fracture toughness of borides formed on boronized ductile iron

    International Nuclear Information System (INIS)

    Sen, Ugur; Sen, Saduman; Koksal, Sakip; Yilmaz, Fevzi

    2005-01-01

    In this study, fracture toughness properties of boronized ductile iron were investigated. Boronizing was realized in a salt bath consisting of borax, boric acid and ferro-silicon. Boronizing heat treatment was carried out between 850 and 950 deg. C under the atmospheric pressure for 2-8 h. Borides e.g. FeB, Fe 2 B formed on ductile iron was verified by X-ray diffraction (XRD) analysis, SEM and optical microscope. Experimental results revealed that longer boronizing time resulted in thicker boride layers. Optical microscope cross-sectional observation of borided layers showed dentricular morphology. Both microhardness and fracture toughness of borided surfaces were measured via Vickers indenter. The harnesses of borides formed on the ductile iron were in the range of 1160-2140 HV 0.1 and fracture toughness were in the range of 2.19-4.47 MPa m 1/2 depending on boronizing time and temperature

  18. Heat treatment effect on ductility of nickel-base alloys

    International Nuclear Information System (INIS)

    Burnakov, K.K.; Khasin, G.A.; Danilov, V.F.; Oshchepkov, B.V.; Listkova, A.I.

    1979-01-01

    Causes of low ductility of the KhN75MBTYu and KhN78T alloys were studied along with the heat treatment effects. Samples were tested at 20, 900, 1100, 1200 deg C. Large amount of inclusions was found in intercrystalline fractures of the above low-ductile alloys. The inclusions of two types took place: (α-Al 2 O 3 , FeO(Cr 2 O 3 xAl 2 O 3 )) dendrite-like ones and large-size laminated SiO 2 , FeO,(CrFe) 2 O 3 inclusions situated as separate colonies. Heat treatment of the alloys does not increase high-temperature impact strength and steel ductility. The heating above 1000 deg C leads to a partial dissolution and coagulation of film inclusions which results in an impact strength increase at room temperature

  19. Ductility of reinforced concrete columns confined with stapled strips

    International Nuclear Information System (INIS)

    Tahir, M.F.; Khan, Q.U.Z.; Shabbir, F.; Sharif, M.B.; Ijaz, N.

    2015-01-01

    Response of three 150x150x450mm short reinforced concrete (RC) columns confined with different types of confining steel was investigated. Standard stirrups, strips and stapled strips, each having same cross-sectional area, were employed as confining steel around four comer column bars. Experimental work was aimed at probing into the affect of stapled strip confinement on post elastic behavior and ductility level under cyclic axial load. Ductility ratios, strength enhancement factor and core concrete strengths were compared to study the affect of confinement. Results indicate that strength enhancement in RC columns due to strip and stapled strip confinement was not remarkable as compared to stirrup confined column. It was found that as compared to stirrup confined column, stapled strip confinement enhanced the ductility of RC column by 183% and observed axial capacity of stapled strip confined columns was 41 % higher than the strip confined columns. (author)

  20. Hot Ductility of the 17-4 PH Stainless Steels

    Science.gov (United States)

    Herrera Lara, V.; Guerra Fuentes, L.; Covarrubias Alvarado, O.; Salinas Rodriguez, A.; Garcia Sanchez, E.

    2016-03-01

    The mechanisms of loss of hot ductility and the mechanical behavior of 17-4 PH alloys were investigated using hot tensile testing at temperatures between 700 and 1100 °C and strain rates of 10-4, 10-2, and 10-1 s-1. Scanning electron microscopy was used in conjunction with the results of the tensile tests to find the temperature region of loss of ductility and correlate it with cracking observed during processing by hot upsetting prior to ring rolling. It is reported that 17-4 PH alloys lose ductility in a temperature range around 900 °C near to the duplex austenite + ferrite phase field. Furthermore, it is found that niobium carbides precipitated at austenite/ferrite interfaces and grain boundaries have a pronounced effect on the mechanical behavior of the alloy during high-temperature deformation.