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Sample records for charpy v-notch impact

  1. Computer simulation of the Charpy V-notch toughness test

    International Nuclear Information System (INIS)

    Norris, D.M. Jr.

    1977-01-01

    The dynamic Charpy V-notch test was simulated on a computer. The calculational models (for A-533 Grade B class 1 steel) used both a rounded and a flat-tipped striker. The notch stress/strain state was found to be independent of the three-point loading type and was most strongly correlated with notch-opening displacement. The dynamic stress/strain state at the time of fracture initiation was obtained by comparing the calculated deformed shape with that obtained in interrupted Charpy V-notch tests where cracking had started. The calculation was also compared with stress/strain states calculated in other geometries at failure. The distribution and partition of specimen energy was calculated and adiabatic heating and strain rate are discussed

  2. Material inertia and size effects in the Charpy V-notch test

    DEFF Research Database (Denmark)

    Desandre, D. A.; Benzerga, A. A.; Tvergaard, Viggo

    2004-01-01

    The effect of material inertia on the size dependence of the absorbed energy in the Charpy V-notch test is investigated. The material response is characterized by an elastic-viscoplastic constitutive relation for a porous plastic solid, with adiabatic heating due to plastic dissipation and the re......The effect of material inertia on the size dependence of the absorbed energy in the Charpy V-notch test is investigated. The material response is characterized by an elastic-viscoplastic constitutive relation for a porous plastic solid, with adiabatic heating due to plastic dissipation...

  3. Weld investigations by 3D analyses of Charpy V-notch specimens

    DEFF Research Database (Denmark)

    Tvergaard, Viggo; Needleman, Allan

    2005-01-01

    The Charpy impact test is a standard procedure for determining the ductile-brittle transition in welds. The predictions of such tests have been investigated by full three dimensional transient analyses of Charpy V-notch specimens. The material response is characterised by an elastic...... parameters in the weld material differ from those in the base material, and the heat a®ected zone (HAZ) tends to be more brittle than the other material regions. The effect of weld strength undermatch or overmatch is an important issue. Some specimens, for which the notched surface is rotated relative...... to the surface of the test piece, have so complex geometry that only a full 3D analysis is able to account for the interaction of failure in the three different material regions, whereas ther specimens can be approximated in terms of a planar analysis....

  4. Determination of the toughness of a low alloy steel from the Charpy V-notch impact testing

    International Nuclear Information System (INIS)

    Rossoll, A.

    1998-12-01

    Charpy V-notch (CVN) impact testing is widely used to characterize the resistance of a material to brittle fracture, by measuring the energy consumed by a specimen during impact. Notably materials undergoing a ductile-to-brittle transition, e.g. ferritic steels, are quality controlled by means of CVN testing, and their ductile-to-brittle transition temperature can be determined. Charpy testing is also widely used in the toughness assessment of large forged components, e.g. pressure vessels for pressurised water reactors (PWR). However, currently no satisfactory link between the Charpy impact energy CVN and the fracture toughness KIc exists. This study aims to establish a non-empirical relationship between the Charpy V-notch energy CVN, and the fracture toughness KIc, on the lower shelf of fracture toughness and the onset of the ductile-to-brittle transition of a A508 Cl.3 steel. The methodology employed is based on the so-called 'local approach'. Brittle cleavage fracture is modelled in terms of the Beremin (1983) model based on 'weakest link' statistics, whereas ductile crack advance preceding cleavage in the transition region is accounted for with the GTN model (Gurson, 1977; Tvergaard, 1982; Tvergaard and Needleman, 1984). Mechanical testing at different strain rates allowed for the establishment of the constitutive equations of the material in an elastic-viscoplastic formulation. Fracture tests on different specimen geometries provided the large data set necessary for statistical evaluation. All specimen types have been modelled with finite element analysis. However, the dynamic nature of the Charpy test requires special consideration. The origin of these dynamic effects was studied, as well as their implications on interpretation of experimental results and on modeling. After a proper modeling procedure had been defined, the local approach was employed for studying fracture. It is found that the fracture toughness can be predicted from the Charpy impact test

  5. Ductile crack initiation in the Charpy V-notch test

    International Nuclear Information System (INIS)

    Server, W.L.; Norris, D.M. Jr.; Prado, M.E.

    1978-01-01

    Initiation and growth of a crack in the Charpy V-notch test was investigated by performing both static and impact controlled deflection tests. Test specimens were deformed to various deflections, heat-tinted to mark crack extension and broken apart at low temperature to allow extension measurements. Measurement of the crack extension provided an estimate of crack initiation as defined by different criteria. Crack initiation starts well before maximum load, and is dependent on the definition of ''initiation''. Using a definition of first micro-initiation away from the ductile blunting, computer model predictions agreed favorably with the experimental results

  6. Charpy Impact Test on Polymeric Molded Parts

    Directory of Open Access Journals (Sweden)

    Alexandra Raicu

    2012-09-01

    Full Text Available The paper presents the Charpy impact tests on the AcrylonitrileButadiene-Styrene (ABS polymeric material parts. The Charpy impact test, also known as the Charpy V-notch test, is a standardized strain rate test which determines the amount of energy absorbed by a material during fracture. This is a typical method described in ASTM Standard D 6110. We use for testing an Instron - Dynatup equipment which have a fully integrated hardware and software package that let us capture load information at very high speed from the impact tests.

  7. Analysis of the Charpy V-notch test for welds

    DEFF Research Database (Denmark)

    Tvergaard, Viggo; Needleman, A.

    2000-01-01

    The ductile-brittle transition for a weld is investigated by numerical analyses of Charpy impact specimens. The material response is characterized by an elastic-viscoplastic constitutive relation for a porous plastic solid, with adiabatic heating due to plastic dissipation and the resulting thermal...... softening accounted for. The onset of cleavage is taken to occur when a critical value of the maximum principal stress is attained. The effect of weld strength undermatch or overmatch is investigated for a comparison material, and analyses are also carried out based on experimentally determined flow...... strength variations in a weldment in a HY100 steel. The predicted work to fracture shows a strong sensitivity to the location of the notch relative to the weld, with the most brittle behavior for a notch close to the narrow heat affected zone. The analyses illustrate the strong dependence of the transition...

  8. On impact testing of subsize Charpy V-notch type specimens

    International Nuclear Information System (INIS)

    Mikhail, A.S.; Nanstad, R.K.

    1994-01-01

    The potential for using subsize specimens to determine the actual properties of reactor pressure vessel steels is receiving increasing attention for improved vessel condition monitoring that could be beneficial for light-water reactor plant-life extension. This potential is made conditional upon, on the one hand, by the possibility of cutting samples of small volume from the internal surface of the pressure vessel for determination of actual properties of the operating pressure vessel. The plant-life extension will require supplemental surveillance data that cannot be provided by the existing surveillance programs. Testing of subsize specimens manufactured from broken halves of previously tested surveillance Charpy V-notch (CVN) specimens offers an attractive means of extending existing surveillance programs. Using subsize CVN type specimens requires the establishment of a specimen geometry that is adequate to obtain a ductile-to-brittle transition curve similar to that obtained from full-size specimens. This requires the development of a correlation of transition temperature and upper-shelf toughness between subsize and full-size specimens. The present study was conducted under the Heavy-Section Steel Irradiation Program. Different published approaches to the use of subsize specimens were analyzed and five different geometries of subsize specimens were selected for testing and evaluation. The specimens were made from several types of pressure vessel steels with a wide range of yield strengths, transition temperatures, and upper-shelf energies (USEs). Effects of specimen dimensions, including depth, angle, and radius of notch have been studied. The correlation of transition temperature determined from different types of subsize specimens and the full-size specimen is presented. A new procedure for transforming data from subsize specimens was developed and is presented

  9. Modeling and simulation of Charpy impact test of maraging steel 300 using Abaqus

    Science.gov (United States)

    Madhusudhan, D.; Chand, Suresh; Ganesh, S.; Saibhargavi, U.

    2018-03-01

    This work emphasizes the modeling and simulation of Charpy impact test to evaluate fracture energy at different pendulum velocities of armor maraging steel 300 using ABAQUS. To evaluate the fracture energy, V-notch specimen is fractured using the Johnson and Cook Damage model. The Charpy impact tests are of great importance related to fracture properties of steels. The objective of this work is to present absorbed energy variation at pendulum velocities of 5 m/sec, 6 m/sec, 7 m/sec and 9 m/sec in addition to stress distribution at v-notch. Finite Element Method of modeling for three dimensional specimens is used for simulation in commercial software of ABAQUS.

  10. Computer simulation of plastic deformation in the Charpy V-notch impact test

    International Nuclear Information System (INIS)

    Norris, D.M. Jr.; Quinones, D.F.; Moran, B.

    1978-01-01

    Calculations describe the dynamic stress and strain states in the standard Charpy specimen from impact to the start of cracking. We model A533 Grade B Class 1 nuclear-pressure-vessel steel at 100 0 C with an elastic-plastic constitutive law. Large deformation and rotation of the material are accounted for. The specimen velocity field during the impact transient is presented and how the early wave effects cause separation of the specimen from the striker is shown. The calculations show why correlations between Charpy fracture energy and fracture toughness have been largely unsuccessful and suggest methods to improve these correlations using the same specimen geometry

  11. Investigation of Ductile-to-Brittle Transition of RPV Materials by using the Pre-cracked Charpy Impact Data

    International Nuclear Information System (INIS)

    Lee, Ho Jin; Lee, Bong Sang; Hong, Jun Hwa

    2005-01-01

    Much recent work in the field of elastic-plastic fracture mechanics has been directed to developing a mechanics-based relationship between the onset of cleavage fracture in structural components and that of Charpy V-notch specimens. The assessing processes of the cracks located in the reactor pressure vessel (RPV) is described in the ASME code Sec. III, App. G and Sec. XI, App. A. The RTNDT obtained from the impact test using standard Charpy V-notch (CVN) specimens is used as a reference temperature to assess the integrity of RPV materials. The initial RTNDT, for the Linde 80 weld, was determined by the 67.8J Charpy impact energy instead of drop weight test. Generally, Linde 80 weld has low upper-shelf energy. The initial RTNDT obtained from the Charpy impact energy curve has been considered overly conservative. Recently, master curve method has been investigated to assess the integrity of RPV materials directly. The initial RTT0 obtained from the master curve method is considered more realistic than the initial RTNDT obtained from impact test for low upper-shelf fracture toughness RPV materials. In this research, the correlation of transition regions between the master curves and the Charpy impact energy curves was investigated using the dynamic fracture toughness curve and the impact energy curve obtained from the impact test of pre-cracked Charpy (PCC) specimens. For the low toughness RPV material the ductile-to-brittle transition corresponding to the static master curve was anticipated using the invested correlation

  12. Application of computer techniques to charpy impact testing of irradiated pressure vessel steels

    International Nuclear Information System (INIS)

    Landow, M.P.; Fromm, E.O.; Perrin, J.S.

    1982-01-01

    A Rockwell AIM 65 microcomputer has been modified to control a remote Charpy V-notch impact test machine. It controls not only handling and testing of the specimen but also transference and storage of instrumented Charpy test data. A system of electrical solenoid activated pneumatic cylinders and switches provides the interface between the computer and the test apparatus. A command language has been designated that allows the operator to command checkout, test procedure, and data storage via the computer. Automatic compliance with ASTM test procedures is built into the program

  13. Laser weld reconstitution of conventional Charpy and Miniaturized Notch Test (MNT) specimens

    International Nuclear Information System (INIS)

    Manahan, M.P.; Williams, J.; Martukanitz, R.P.

    1993-01-01

    As nuclear power plants approach end-of-license (EOL) and consideration is given to license renewal, there is an ever increasing need to expand the amount of data obtainable from the original surveillance specimens. A laser welding technique to reconstitute broken Charpy specimens is being developed to produce both conventional and miniaturized Charpy specimens. This paper reports on early laser welding development efforts and summarizes previous proof-of-principle experiments on a 1/16 scale miniaturized Charpy test. In order to benchmark the laser welding procedure, the laser-reconstituted specimen data have been compared with the original specimen data. In addition, the microstructure after welding has been examined to ensure that the material in the vicinity of the notch is essentially unchanged after the welding process. Data which characterize the thermal transient during welding are obtained by attaching thermocouples to the specimens. Other important considerations include perturbation of the stress field near the notch, dynamic stress waves, and contact of the weld region with the tup. Precise control of welding parameters has been demonstrated, heat-affected zones as small as 0.25 mm can be achieved, and sufficient penetration depth can be obtained to enable welding thick sections (1T or greater) to yield conventional Charpy specimens or fracture toughness specimens and thin sections (∼5 mm) to yield Miniaturized Notch Test (MNT) specimens

  14. Effects of annealing time on the recovery of Charpy V-notch properties of irradiated high-copper weld metal

    International Nuclear Information System (INIS)

    Iskander, S.K.; Sokolov, M.A.; Nanstad, R.K.

    1994-01-01

    One of the options to mitigate the effects of irradiation on reactor pressure vessels is to thermally anneal them to restore the toughness properties that have been degraded by neutron irradiation. An important issue to be resolved is the effect on the toughness properties of reirradiating a vessel that has been annealed. This paper describes the annealing response of irradiated high-copper submerged-arc weld HSSI 73W. For this study, the weld has been annealed at 454 C (850 F) for lengths of time varying between 1 and 14 days. The Charpy V-notch 41-J (30-ft-lb) transition temperature (TT 41J ) almost fully recovered for the longest period studied, but recovered to a lesser degree for the shorter periods. No significant recovery of the TT 41J was observed for a 7-day anneal at 343 C (650 F). At 454 C for the durations studied, the values of the upper-shelf impact energy of irradiated and annealed weld metal exceeded the values in the unirradiated condition. Similar behavior was observed after aging the unirradiated weld metal at 460 and 490 C for 1 week

  15. Analysis of impact energy to fracture un-notched charpy specimens made from railroad tank car steel

    Science.gov (United States)

    2007-09-11

    This paper describes a nonlinear finite element analysis : (FEA) framework that examines the impact energy to fracture : unnotched Charpy specimens by an oversized, nonstandard : pendulum impactor called the Bulk Fracture Charpy Machine : (BFCM). The...

  16. Charpy V, an application in Mat lab; Charpy V, una aplicacion en Matlab

    Energy Technology Data Exchange (ETDEWEB)

    Castillo M, J.A.; Torres V, M. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2003-07-01

    The obtained results with the system Charpy V{sub V}1 designed in Mat lab for the estimate of parameters of three mathematical models are shown. The adjustment of data is used to determine the fracture energy, the lateral expansion and the percentage of ductility of steels coming from the reactor vessels of Laguna Verde, Veracruz. The data come from test tubes type Charpy V of irradiated material and not irradiated. To verify our results they were compared with those obtained by General Electric of data coming from the Laguna Verde nuclear power plant. (Author)

  17. Use of forces from instrumented Charpy V-notch testing to determine crack-arrest toughness

    International Nuclear Information System (INIS)

    Iskander, S.K.; Nanstad, R.K.; Sokolov, M.A.; McCabe, D.E.; Hutton, J.T.

    1996-06-01

    The objective of this investigation is an estimation of the crack-arrest toughness, particularly of irradiated materials, from voltage versus time output of an instrumented setup during a test on a Charpy V-notch (CVN) specimen. This voltage versus time trace (which can be converted to force versus displacement) displays events during fracture of the specimen. Various stages of the fracture process can be identified on the trace, including an arrest point indicating arrest of brittle fracture. The force at arrest, F a , versus test temperature, T, relationship is examined to explore possible relationships to other experimental measures of crack-arrest toughness such as the drop-weight nil-ductility temperature (NDT), or crack-arrest toughness, K a . For a wide range of weld and plate materials, the temperature at which F a = 2.45 kN correlates with NDT with a standard deviation, sigma, of about 11 K. Excluding the so-called low upper-shelf energy (USE) welds from the analysis resulted in F a = 4.12 kN and σ = 6.6 K. The estimates of the correlation of the temperature for F a = 7.4 kN with the temperature at 100-MPa√m level for a mean American Society of Mechanical Engineers (ASME) type K Ia curve through crack-arrest toughness values show that prediction of conservative values of K a are possible

  18. Results of charpy V-notch impact testing of structural steel specimens irradiated at ∼30 degrees C to 1 x 1016 neutrons/cm2 in a commercial reactor cavity

    International Nuclear Information System (INIS)

    Iskander, S.K.; Stoller, R.E.

    1997-04-01

    A capsule containing Charpy V-notch (CVN) and mini-tensile specimens was irradiated at ∼ 30 degrees C (∼ 85 degrees F) in the cavity of a commercial nuclear power plant to a fluence of 1 x 10 16 neutrons/cm 2 (> 1MeV). The capsule included six CVN impact specimens of archival High Flux Isotope Reactor A212 grade B ferritic steel and five CVN impact specimens of a well-studied A36 structural steel. This irradiation was part of the ongoing study of neutron-induced damage effects at the low temperature and flux experienced by reactor supports. The plant operators shut down the plant before the planned exposure was reached. The exposure of these specimens produced no significant irradiation-induced embrittlement. Of interest were the data on unirradiated specimens in the L-T orientation machined from a single plate of A36 structural steel, which is the same specification for the structural steel used in some reactor supports. The average CVN energy of five unirradiated specimens obtained from one region of the plate and tested at room temperature was ∼ 99 J, while the energy of 11 unirradiated specimens from other locations of the same plate was 45 J, a difference of ∼ 220%. The CVN impact energies for all 18 specimens ranged from a low of 32 J to a high of 111 J. Moreover, it appears that the University of Kansas CVN impact energy data of the unirradiated specimens at the 100-J level are shifted toward higher temperatures by about 20 K. The results were an example of the extent of scatter possible in CVN impact testing. Generic values for the CVN impact energy of A36 should be used with caution in critical applications

  19. Miniaturized Charpy test for reactor pressure vessel embrittlement characterization

    Energy Technology Data Exchange (ETDEWEB)

    Manahan, M.P. Sr. [MPM Research and Consulting, Lemont, PA (United States)

    1999-10-01

    Modifications were made to a conventional Charpy machine to accommodate the miniaturized Charpy V-Notch (MCVN) specimens which were fabricated from an archived reactor pressure vessel (RPV) steel. Over 100 dynamic MCVN tests were performed and compared to the results from conventional Charpy V-Notch (CVN) tests to demonstrate the efficacy of the miniature specimen test. The optimized sidegrooved MCVN specimens exhibit transitional fracture behavior over essentially the same temperature range as the CVN specimens which indicates that the stress fields in the MCVN specimens reasonably simulate those of the CVN specimens and this fact has been observed in finite element calculations. This result demonstrates a significant breakthrough since it is now possible to measure the ductile-brittle transition temperature (DBTT) using miniature specimens with only small correction factors, and for some materials as in the present study, without the need for any correction factor at all. This development simplifies data interpretation and will facilitate future regulatory acceptance. The non-sidegrooved specimens yield energy-temperature data which is significantly shifted downward in temperature (non-conservative) as a result of the loss of constraint which accompanies size reduction.

  20. Charpy V, an application in Mat lab

    International Nuclear Information System (INIS)

    Castillo M, J.A.; Torres V, M.

    2003-01-01

    The obtained results with the system Charpy V V 1 designed in Mat lab for the estimate of parameters of three mathematical models are shown. The adjustment of data is used to determine the fracture energy, the lateral expansion and the percentage of ductility of steels coming from the reactor vessels of Laguna Verde, Veracruz. The data come from test tubes type Charpy V of irradiated material and not irradiated. To verify our results they were compared with those obtained by General Electric of data coming from the Laguna Verde nuclear power plant. (Author)

  1. Charpy impact test of oxidized and hydrogenated zircaloy using a thin strip specimen

    International Nuclear Information System (INIS)

    Otsuka, Teppei; Hashizume, Kenichi; Sugisaki, Masayasu

    2004-01-01

    The impact properties of an oxidized and a hydrogenated Zircaloy have been studied with an instrumented Charpy machine by using a strip Charpy V-notch specimen (1 mm thick by 4mm wide). Fracture processes such as crack initiation and propagation were examined using load-displacement curves obtained in this study. In the case of the hydrogenated specimen containing preferentially oriented hydrides, an appreciable decrease in the absorbed energy was observed in the crack propagation rather than in the crack initiation. From results of fractographs of the specimen, it was suggested that the reduction of the crack propagation energy of hydrogenated specimen could be attributed to the change of the stress state in the Zircaloy matrix, which was caused by the fracture of hydride in the inner part of specimen. In the case of the specimen oxidized at 973k for 60 min, on which an oxide layer (4 μm in thickness) and oxygen incursion layer (4μm) were formed, the surface layers affected the crack initiation process. The growing oxygen incursion layer, in particular, resulted in the constraint of plastic deformation of the Zircaloy matrix not only in the crack initiation but also in the crack propagation as its thickness increased. (author)

  2. Instrumented impact testing as a way to obtain further information on the behaviour of steel in welded constructions

    International Nuclear Information System (INIS)

    Nielsen, A.

    1976-05-01

    Based on experience gained from instrumented impact testing of ten different mild steels using test pieces of different geometrical shape (Charpy V-notch, Charpy knife-notch, DVM, Schnadt K 0 , Ksub(0.5), K 1 and K 2 ), some general features of the fracture process during impact testing are discussed. Steels can be divided into two main groups that are significantly different with respect to the behaviour during Charpy V-notch testing. The difference vanishes when a crack-like notch is used, and other properties of steel are revealed. It is evident that, even when modified impact testing bears little resemblance to what is happening in an actual steel construction. For the purpose of investigating the fracture conditions in welds, it seems more significant to relate the dynamic aspects to the speed of propagation of the crack when it starts to penetrate the volume considered at a certain stress level. (author)

  3. Ultrahigh Charpy impact toughness (~450J) achieved in high strength ferrite/martensite laminated steels

    Science.gov (United States)

    Cao, Wenquan; Zhang, Mingda; Huang, Chongxiang; Xiao, Shuyang; Dong, Han; Weng, Yuqing

    2017-02-01

    Strength and toughness are a couple of paradox as similar as strength-ductility trade-off in homogenous materials, body-centered-cubic steels in particular. Here we report a simple way to get ultrahigh toughness without sacrificing strength. By simple alloying design and hot rolling the 5Mn3Al steels in ferrite/austenite dual phase temperature region, we obtain a series of ferrite/martensite laminated steels that show up-to 400-450J Charpy V-notch impact energy combined with a tensile strength as high as 1.0-1.2 GPa at room temperature, which is nearly 3-5 times higher than that of conventional low alloy steels at similar strength level. This remarkably enhanced toughness is mainly attributed to the delamination between ferrite and martensite lamellae. The current finding gives us a promising way to produce high strength steel with ultrahigh impact toughness by simple alloying design and hot rolling in industry.

  4. Dynamic Toughness Testing of Pre-Cracked Charpy V-Notch Specimens. Convention ELECTRABEL - SCK-CEN

    Energy Technology Data Exchange (ETDEWEB)

    Lucon, E

    1999-04-01

    This document describes the experimental and analytical procedures which have been adopted at the laboratories of the Belgian Nuclear Research Centre SCK-CEN for performing dynamic toughness tests on pre-cracked Charpy-V specimens. Such procedures were chosen on the basis of the existing literature on the subject, with several updates in the data analysis stages which reflect more recent developments in fracture toughness testing. Qualification tests have been carried out on PCCv specimens of JRQ steel, in order to assess the reliability of the results obtained; straightforward comparisons with reference data have been performed, as well as more advanced analyses using the Master Curve approach. Aspects related to machine compliance and dynamic tup calibration have also been addressed.

  5. Tensile and charpy impact properties of irradiated reduced-activation ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Klueh, R.L.; Alexander, D.J. [Oak Ridge National Lab., TN (United States)

    1996-10-01

    Tensile tests were conducted on eight reduced-activation Cr-W steels after irradiation to 15-17 and 26-29 dpa, and Charpy impact tests were conducted on the steels irradiated to 26-29 dpa. Irradiation was in the Fast Flux Test Facility at 365{degrees}C on steels containing 2.25-12% Cr, varying amounts of W, V, and Ta, and 0.1%C. Previously, tensile specimens were irradiated to 6-8 dpa and Charpy specimens to 6-8, 15-17, and 20-24 dpa. Tensile and Charpy specimens were also thermally aged to 20000 h at 365{degrees}C. Thermal aging had little effect on the tensile behavior or the ductile-brittle transition temperature (DBTT), but several steels showed a slight increase in the upper-shelf energy (USE). After {approx}7 dpa, the strength of the steels increased and then remained relatively unchanged through 26-29 dpa (i.e., the strength saturated with fluence). Post-irradiation Charpy impact tests after 26-29 dpa showed that the loss of impact toughness, as measured by an increase in DBTT and a decrease in the USE, remained relatively unchanged from the values after 20-24 dpa, which had been relatively unchanged from the earlier irradiations. As before, the two 9Cr steels were the most irradiation resistant.

  6. A study on the Charpy-V impact energy and impact properties of stainless steel

    International Nuclear Information System (INIS)

    Han, Gill Young

    1988-01-01

    It has been thought that by analyzing and considering the shock strength and fracture of impact load. We can accurtely determine strength and thus it will be helpful in optimum design. In this experimental study the following results were obtained by using the instrumented impact test for SUS 316 1) The total charpy impact energy is progressively decreased by increasing the shock pressure. 2) The dynamic yield strength is increased by increasing the shock pressure for all test temperatures. 3) The ratio of dynamic yield to static yield strength was found to decrease with increasing shock pressure. (Author)

  7. Microstructural characterization of Charpy-impact-tested nanostructured bainite

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Y.T.; Chang, H.T.; Huang, B.M. [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan, ROC (China); Huang, C.Y. [Iron and Steel R& D Department, China Steel Corporation, Kaohsiung, Taiwan, ROC (China); Yang, J.R., E-mail: jryang@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan, ROC (China)

    2015-09-15

    In this work, a possible cause of the extraordinary low impact toughness of nanostructured bainite has been investigated. The microstructure of nanostructured bainite consisted chiefly of carbide-free bainitic ferrite with retained austenite films. X-ray diffractometry (XRD) measurement indicated that no retained austenite existed in the fractured surface of the Charpy-impact-tested specimens. Fractographs showed that cracks propagated mainly along bainitic ferrite platelet boundaries. The change in microstructure after impact loading was verified by transmission electron microscopy (TEM) observations, confirming that retained austenite was completely transformed to strain-induced martensite during the Charpy impact test. However, the zone affected by strained-induced martensite was found to be extremely shallow, only to a depth of several micrometers from the fracture surface. It is appropriately concluded that upon impact, as the crack forms and propagates, strain-induced martensitic transformation immediately occurs ahead of the advancing crack tip. The successive martensitic transformation profoundly facilitates the crack propagation, resulting in the extremely low impact toughness of nanostructured bainite. Retained austenite, in contrast to its well-known beneficial role, has a deteriorating effect on toughness during the course of Charpy impact. - Highlights: • The microstructure of nanostructured bainite consisted of nano-sized bainitic ferrite subunits with retained austenite films. • Special sample preparations for SEM, XRD and TEM were made, and the strain-affected structures have been explored. • Retained austenite films were found to transform into martensite after impact loading, as evidenced by XRD and TEM results. • The zone of strain-induced martensite was found to extend to only several micrometers from the fracture surface. • The poor Charpy impact toughness is associated with the fracture of martensite at a high strain rate during

  8. Influence of thermal conditioning media on Charpy specimen test temperature

    International Nuclear Information System (INIS)

    Nanstad, R.K.; Swain, R.L.; Berggren, R.G.

    1989-01-01

    The Charpy V-notch (CVN) impact test is used extensively for determining the toughness of structural materials. Research programs in many technologies concerned with structural integrity perform such testing to obtain Charpy energy vs temperature curves. American Society for Testing and Materials Method E 23 includes rather strict requirements regarding determination and control of specimen test temperature. It specifies minimum soaking times dependent on the use of liquids or gases as the medium for thermally conditioning the specimen. The method also requires that impact of the specimen occur within 5 s removal from the conditioning medium. It does not, however, provide guidance regarding choice of conditioning media. This investigation was primarily conducted to investigate the changes in specimen temperature which occur when water is used for thermal conditioning. A standard CVN impact specimen of low-alloy steel was instrumented with surface-mounted and embedded thermocouples. Dependent on the media used, the specimen was heated or cooled to selected temperatures in the range -100 to 100 degree C using cold nitrogen gas, heated air, acetone and dry ice, methanol and dry ice, heated oil, or heated water. After temperature stabilization, the specimen was removed from the conditioning medium while the temperatures were recorded four times per second from all thermocouples using a data acquisition system and a computer. The results show that evaporative cooling causes significant changes in the specimen temperatures when water is used for conditioning. Conditioning in the other media did not result in such significant changes. The results demonstrate that, even within the guidelines of E 23, significant test temperature changes can occur which may substantially affect the Charpy impact test results if water is used for temperature conditioning. 7 refs., 11 figs

  9. Validation Study of Unnotched Charpy and Taylor-Anvil Impact Experiments using Kayenta

    Energy Technology Data Exchange (ETDEWEB)

    Kamojjala, Krishna [Idaho National Lab. (INL), Idaho Falls, ID (United States); Lacy, Jeffrey [Idaho National Lab. (INL), Idaho Falls, ID (United States); Chu, Henry S. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Brannon, Rebecca [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-03-01

    Validation of a single computational model with multiple available strain-to-failure fracture theories is presented through experimental tests and numerical simulations of the standardized unnotched Charpy and Taylor-anvil impact tests, both run using the same material model (Kayenta). Unnotched Charpy tests are performed on rolled homogeneous armor steel. The fracture patterns using Kayenta’s various failure options that include aleatory uncertainty and scale effects are compared against the experiments. Other quantities of interest include the average value of the absorbed energy and bend angle of the specimen. Taylor-anvil impact tests are performed on Ti6Al4V titanium alloy. The impact speeds of the specimen are 321 m/s and 393 m/s. The goal of the numerical work is to reproduce the damage patterns observed in the laboratory. For the numerical study, the Johnson-Cook failure model is used as the ductile fracture criterion, and aleatory uncertainty is applied to rate-dependence parameters to explore its effect on the fracture patterns.

  10. Numerical modelling of Charpy-V notch test by local approach to fracture. Application to an A508 steel in the ductile-brittle transition range

    International Nuclear Information System (INIS)

    Tanguy, B.

    2001-07-01

    Ferritic steels present a transition of the rupture mode which goes progressively of a brittle rupture (cleavage) to a ductile rupture when the temperature increases. The following of the difference of the transition temperature of the PWR vessel steel by the establishment of toughness curves makes of the Charpy test an integrating part of the monitoring of the French PWR reactors. In spite of the advantages which are adapted to it in particular its cost, the Charpy test does not allow to obtain directly a variable which characterizes a crack propagation resistance as for instance the toughness used for qualifying the mechanical integrity of a structure. This work deals with the establishment of the through impact strength-toughness in the transition range of the vessel steel: 16MND5 from a non-empirical approach based on the local approach of the rupture. The brittle rupture is described by the Beremin model (1983), which allows to describe the dispersion inherent in this rupture mode. The description of the brittle fissure is carried out by the GTN model (1984) and by the Rousselier model (1986). This last model has been modified in order to obtain a realistic description of the brittle damage in the case of fast solicitations and of local heating. The method proposed to determine the parameters of the damage models depends only of tests on notched specimens and of the inclusion data of the material. The behaviour is described by an original formulation parametrized in temperature which allows to describe all the tests carried out in this study. Before using this methodology, an experimental study of the behaviour and of the rupture modes of the steel 16MND5 has been carried out. From the toughness tests carried out in quasi-static and dynamical conditions, it has been revealed that this steel does not present important unwedging of its toughness curve due to the velocity effect. In the transition range, local heating of about 150 C have been measured in the root

  11. Effect of notch dimension on the fatigue life of V-notched structure

    International Nuclear Information System (INIS)

    Cheng Changzheng; Naman, Recho; Niu Zhongrong; Zhou Huanlin

    2011-01-01

    Highlights: → A novel method is proposed to calculate the SIFs of crack at notch tip. → Effect of notch opening angle on the crack extension and propagation is studied. → Influence of notch depth on the crack extension and propagation is analyzed. → The fatigue life of a welded joint is analyzed by the present method. - Abstract: The stress singularity degree associated to a V-notch has a great influence on the fatigue life of V-notched structure. The growth rate of the crack initiated at the tip of a V-notch depends on the stress singularity of the V-notch. The fatigue life accompanying with this small crack will represent a large amount of the total fatigue life. In this work, boundary element method (BEM) is used to study the propagation of the crack emanating from a V-notch tip under fatigue loading. A comparison of the fatigue life between the crack initiated from V-notch tip and a lateral crack is done by a crack propagation law until these two cracks have the same stress intensity factors (SIFs). The effect of initial crack length, notch opening angle and notch depth on the crack extension and propagation is analyzed. As an example of engineering application, the fatigue life of a welded joint is investigated by the present method. The influence of weld toe angle and initial crack length on the fatigue life of the welded structure is studied. Some suggestions are given as an attempt to improve the fatigue life of welded structures at the end.

  12. Charpy impact test results on five materials and NIST verification specimens using instrumented 2-mm and 8-mm strikers

    International Nuclear Information System (INIS)

    Nanstad, R.K.; Sokolov, M.A.

    1995-01-01

    The Heavy-Section Steel Irradiation Program at Oak Ridge National Laboratory is involved in two cooperative projects, with international participants, both of which involve Charpy V-notch impact tests with instrumented strikers of 2mm and 8mm radii. Two heats of A 533 grade B class I pressure vessel steel and a low upper-shelf (LUS) submerged-arc (SA) weld were tested on the same Charpy machine, while one heat of a Russian Cr-Mo-V forging steel and a high upper-shelf (HUS) SA weld were tested on two different machines. The number of replicate tests at any one temperature ranged from 2 to 46 specimens. Prior to testing with each striker, verification specimens at the low, high, and super high energy levels from the National Institute of Standards and Technology (NIST) were tested. In the two series of verification tests, the tests with the 2mm striker met the requirements at the low and high energy levels but not at the super high energy. For one plate, the 2mm striker showed somewhat higher average absorbed energies than those for the 8-mm striker at all three test temperatures. For the second plate and the LUS weld, however, the 2mm striker showed somewhat lower energies at both test temperatures. For the Russian forging steel and the HUS weld, tests were conducted over a range of temperatures with tests at one laboratory using the 8mm striker and tests at a second laboratory using the 2mm striker. Lateral expansion was measured for all specimens and the results are compared with the absorbed energy results. The overall results showed generally good agreement (within one standard deviation) in energy measurements by the two strikers. Load-time traces from the instrumented strikers were also compared and used to estimate shear fracture percentage. Four different formulas from the European Structural Integrity Society draft standard for instrumented Charpy test are compared and a new formula is proposed for estimation of percent shear from the force-time trace

  13. ASK Procedure for Instrumented Pre-cracked Charpy-Type Tests

    International Nuclear Information System (INIS)

    Varga, T.; Njo, D.H.; Prantl, G.

    1981-01-01

    The essential technical content of the ASK procedure originated from development work in Switzerland since 1963, and practical experiences gained since 1972. The remainder of the content and the format of the procedure are based on the ASTM E 24.03.03. (Tentative Draft Copy) 'Proposed Method for Pre-cracked Charpy Impact and Slow-Bend Testing of Metallic Materials' by C. E. Harbower, 1973. Two different velocities, 5 m/s and 0.1 m/s were used with a Schnadt-type machine of rigid construction. The stiffness of the machine proved to be very suitable for instrumented testing. The instrumented Schnadt-Type machine was equipped with strain gauges both on the top of the pendulum and on the chisel. A static force calibration was followed by energy calibration, comparing potential energy losses with the area under the force-deflection curve. Deflection was measured using a high frequency eddy current method on the pendulum, and for slow testing by means of an inductive gauge on the chisel. Charpy-Type specimens of 1.0 mm max notch depth and 0.12 mm max notch radius were pre-cracked using a resonant fatigue testing machine, or an eccentric drive machine. Crack propagation rate da/dN was measured using 'Russenberger' measuring gauges. In addition a new technique for the detection of dynamic crack initiation, developed at the Institute of Research and Technology (TVFA) in Vienna is discussed and some results presented

  14. Use of precracked Charpy and smaller specimens to establish the master curve

    International Nuclear Information System (INIS)

    Sokolov, M.A.; McCabe, D.E.; Nanstad, R.K.; Davidov, Y.A.

    1997-01-01

    The current provisions used in the U.S. Code of Federal Regulations for the determination of the fracture toughness of reactor pressure vessel steels employs an assumption that there is a direct correlation between K Ic lower-bound toughness and the Charpy V-notch transition curve. Such correlations are subject to scatter from both approaches which weakens the reliability of fracture mechanics-based analyses. In this study, precracked Charpy and smaller size specimens are used in three-point static bend testing to develop fracture mechanics based K k values. The testing is performed under carefully controlled conditions such that the values can be used to predict the fracture toughness performance of large specimens. The concept of a universal transition curve (master curve) is applied. Data scatter that is characteristic of commercial grade steels and their weldments is handled by Weibull statistical modeling. The master curve is developed to describe the median K Jc fracture toughness for 1T size compact specimens. Size effects are modeled using weakest-link theory and are studied for different specimen geometries. It is shown that precracked Charpy specimens when tested within their confined validity limits follow the weakest-link size-adjustment trend and predict the fracture toughness of larger specimens. Specimens of smaller than Charpy sizes (5 mm thick) exhibit some disparities in results relative to weakest-link size adjustment prediction suggesting that application of such adjustment to very small specimens may have some limitations

  15. On the Effectiveness of the Dynamic Force Adjustment for Reducing the Scatter of Instrumented Charpy Results

    International Nuclear Information System (INIS)

    Lucon, E.

    2008-01-01

    One of the key factors for obtaining reliable instrumented Charpy results is the calibration of the instrumented striker. An interesting alternative to the conventional static calibration recommended by the standards is the Dynamic Force Adjustment (DFA), in which forces and displacements are iteratively adjusted until equality is achieved between absorbed energies calculated under the test record (Wt) and measured by the machine encoder (KV). In this study, this procedure has been applied to the instrumented data obtained by 10 international laboratories using notched and precracked Charpy specimens, in the framework of a Coordinated Research Project (CRP8) of IAEA. DFA is extremely effective in reducing the between-laboratory scatter for both general yield and maximum forces. The effect is less significant for dynamic reference temperatures measured from precracked Charpy specimens using the Master Curve procedure, but a moderate reduction of the standard deviation is anyway observed. It is shown that striker calibration is a prominent contribution to the interlaboratory variability of instrumented impact forces, particularly in the case of maximum forces.

  16. On the Effectiveness of the Dynamic Force Adjustment for Reducing the Scatter of Instrumented Charpy Results

    Energy Technology Data Exchange (ETDEWEB)

    Lucon, E.

    2008-09-15

    One of the key factors for obtaining reliable instrumented Charpy results is the calibration of the instrumented striker. An interesting alternative to the conventional static calibration recommended by the standards is the Dynamic Force Adjustment (DFA), in which forces and displacements are iteratively adjusted until equality is achieved between absorbed energies calculated under the test record (Wt) and measured by the machine encoder (KV). In this study, this procedure has been applied to the instrumented data obtained by 10 international laboratories using notched and precracked Charpy specimens, in the framework of a Coordinated Research Project (CRP8) of IAEA. DFA is extremely effective in reducing the between-laboratory scatter for both general yield and maximum forces. The effect is less significant for dynamic reference temperatures measured from precracked Charpy specimens using the Master Curve procedure, but a moderate reduction of the standard deviation is anyway observed. It is shown that striker calibration is a prominent contribution to the interlaboratory variability of instrumented impact forces, particularly in the case of maximum forces.

  17. Evaluation of toughness deterioration by an electrochemical method in an isothermally-aged N-containing austenitic stainless steel

    International Nuclear Information System (INIS)

    Saucedo-Munoz, Maribel L.; Lopez-Hirata, Victor M.; Avila-Davila, Erika O.; Melo-Maximo, Dulce V.

    2009-01-01

    This work presents the results of an evaluation of the deterioration of cryogenic toughness by means of an electrochemical method in a N-containing austenitic stainless steel (JK2) aged at temperatures of 700, 800 and 900 deg. C for times from 10 to 1000 min. The aging process at 700 and 800 deg. C caused the decrease in the Charpy V-Notch impact energy at - 196 deg. C because of the intergranular precipitation of carbides. Scanning electron micrographs of the Charpy V-Notch test specimens showed the presence of intergranular brittle fracture. The degree of sensitization was determined by the ratio of the maximum current density generated by the reactivation scan to that of the anodic scan, I r /I a , using the double-loop electrochemical potentiokinetic reactivation test. The Charpy V-Notch impact energy decreased with increase in the I r /I a ratio. This relation permits an estimate of the deterioration of cryogenic toughness due to thermal aging in this type of steel

  18. Correlations between Standard and Miniaturised Charpy-V Specimens

    International Nuclear Information System (INIS)

    Lucon, E.; Van Walle, E.; Fabry, A.; Puzzolante, J.-L.; Verstrepen, A.; Vosch, R.; Van de Velde, L.

    1998-12-01

    A total of 565 instrumented impact tests (232 performed on full-size and 333 on sub-size Charpy-V specimens) have been analysed in order to derive meaningful assumptions on the correlations existing between test results obtained on specimens of different size. Nine materials (pressure vessel steels) have been considered, in both as-received and irradiated state, for a total of 19 conditions examined. For the analysis of data, conventional as well novel approaches have been investigated; former ones, based on a review of the existing literature, include predictions of USE values by the use of normalization factors (NF), shifts of index temperatures related to energy/lateral expansion/shear fracture levels, and a combination of both approaches (scaling and shifting of energy curves). More original and recent proposals have also been verified, available in the literature but also proposed by SCK-CEN in the frame of enhanced surveillance of nuclear reactor pressure vessels. Conclusions have been drawn regarding the applicability and reliability of these methodologies, and recommendations have been given for future developments of the activities on this topic

  19. Prediction of fracture toughness K/sub Ic/ of steel from Charpy impact test results

    Energy Technology Data Exchange (ETDEWEB)

    Iwadate, Tadao; Tanaka, Yasuhiko; Takemata, Hiroyuki; Terashima, Shuhei

    1986-08-01

    This paper presents a method to predict the fracture toughness K/sub Ic/ and/or K/sub Id/ of steels using their Charpy impact test results and tensile properties. The fracture toughness, Charpy impact and tensile properties of 2 1/4 Cr-1Mo, ASTM A508 Cl.1, A508 Cl.2 A508 Cl.3 and A533 Gr.B Cl.1 steels were measured and analysed on the basis of the excess temperature (test temperature minus FATT) and Rolfe-Novak correlation. The relationship between K/sub Ic//K/sub Ic-us/ and the excess temperature, where K/sub Ic-us/ is the upper-shelf fracture toughness K/sub Ic/ predicted by Rolfe-Novak correlation, discloses that the K/sub Ic/ transition curves of several steels are representable by only one trend curve of K/sub Ic//K/sub Ic-us/ or K/sub Id//K/sub Id-us/ versus excess temperature relation. This curve is denoted as a ''master curve''. By using this curve, the fracture toughness of steel can be predicted using Charpy impact and tensile test results. By taking account of the scattering of both the fracture toughness and Charpy impact test results, the confidence limits of the master curve were also determined. Another approach to develop more general procedure of predicting the fracture toughness K/sub Ic/ is also discussed.

  20. Application of subsize specimens in nuclear plant life extension

    International Nuclear Information System (INIS)

    Rosinski, S.T.; Kumar, A.S.; Cannon, N.S.; Hamilton, M.L.

    1993-01-01

    The US Department of Energy is sponsoring a research effort through Sandia National Laboratories and the University of Missouri-Rolla to test a correlation for the upper shelf energy (USE) values obtained from the impact testing of subsize Charpy V-notch specimens to those obtained from the testing of full-size samples. The program involves the impact testing of unirradiated and irradiated full-, half-, and third-size Charpy V-notch specimens. To verify the applicability of the correlation on LWR materials, unirradiated and irradiated full-, half-, and third-size Charpy V-notch specimens of a commercial pressure vessel steel (ASTM A533 Grade B) will be tested. The correlation methodology is based on the partitioning of the USE into crack initiation and crack propagation energies. To accomplish this partition, both precracked and notched-only specimens will be used. Whereas the USE of notched-only specimens is the sum of both crack initiation and crack propagation energies, the USE of precracked specimens reflects only the crack propagation component. The difference in the USE of the two types of specimens represents a measure of the crack initiation energy. Normalizing the values of the crack initiation energy to the fracture volume of the sample produces similar values for the full-, half-, and third-size specimens. In addition, the ratios of the USE and the crack propagation energy are also in agreement for full-, half-, and third-size specimens. These two observations will be used to predict the USE of full-size specimens based on subsize USE data. This paper provides details of the program and presents results obtained from the application of the developed correlation methodology to the impact testing of the unirradiated full-, half-, and third-size A533 Grade B Charpy V-notch specimens

  1. Application of Instrumented Charpy Method in Characterisation of Materials

    Directory of Open Access Journals (Sweden)

    Željko Alar

    2015-07-01

    Full Text Available Testing of absorbed impact energy according to the Charpy method is carried out to determine the behaviour of a material under the impact load. Instrumented Charpy method allows getting the force displacement curve through the entire test, That curve can be related to force-displacement curve which is obtained by the static tensile test. The purpose of this study was to compare the results of forces obtained by the static tensile test with the forces obtained by the instrumented Charpy method. Experimental part of the work contains testing of the mechanical properties of S275J0 steel by the static tensile test and Impact test on instrumented Charpy pendulum.

  2. Evaluation and uncertainty estimates of Charpy-impact data

    International Nuclear Information System (INIS)

    Stallman, F.W.

    1982-01-01

    Shifts in transition temperature and upper-shelf energy from Charpy tests are used to determine the extent of radiation embrittlement in steels. In order to determine these parameters reliably and to obtain uncertainty estimates, curve fitting procedures need to be used. The hyperbolic tangent or similar models have been proposed to fit the temperature-impact-energy curve. These models are not based on the actual fracture mechanics and are indeed poorly suited in many applications. The results may be falsified by forcing an inflexible curve through too many data points. The nonlinearity of the fit poses additional problems. In this paper, a simple linear fit is proposed. By eliminating data which are irrelevant for the determination of a given parameter, better reliability and accuracy can be achieved. Additional input parameters like fluence and irradiation temperature can be included. This is important if there is a large variation of fluence and temperature in different test specimens. The method has been tested with Charpy specimens from the NRC-HSST experiments

  3. Experimental study on variations in Charpy impact energies of low carbon steel, depending on welding and specimen cutting method

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhaorui; Kang, Hansaem; Lee, Young Seog [Chung-Ang University, Seoul (Korea, Republic of)

    2016-05-15

    This paper presents an experimental study that examines variations of Charpy impact energy of a welded steel plate, depending upon the welding method and the method for obtaining the Charpy specimens. Flux cored arc welding (FCAW) and Gas tungsten arc welding (GTAW) were employed to weld an SA516 Gr. 70 steel plate. The methods of wire cutting and water-jet cutting were adopted to take samples from the welded plate. The samples were machined according to the recommendations of ASTM SEC. II SA370, in order to fit the specimen dimension that the Charpy impact test requires. An X-ray diffraction (XRD) method was used to measure the as-weld residual stress and its redistribution after the samples were cut. The Charpy impact energy of specimens was considerably dependent on the cutting methods and locations in the welded plate where the specimens were taken. The specimens that were cut by water jet followed by FCAW have the greatest resistance-to-fracture (Charpy impact energy). Regardless of which welding method was used, redistributed transverse residual stress becomes compressive when the specimens are prepared using water-jet cutting. Meanwhile, redistributed transverse residual stress becomes tensile when the specimens are prepared using wire cutting.

  4. Application of Instrumented Charpy Method in Characterisation of Materials

    OpenAIRE

    Alar, Željko; Mandić, Davor; Dugorepec, Andrija; Sakoman, Matija

    2015-01-01

    Testing of absorbed impact energy according to the Charpy method is carried out to determine the behaviour of a material under the impact load. Instrumented Charpy method allows getting the force displacement curve through the entire test, That curve can be related to force-displacement curve which is obtained by the static tensile test. The purpose of this study was to compare the results of forces obtained by the static tensile test with the forces obtained by the instrumented Charpy method...

  5. The interpretation of Charpy impact test data using hyper-logistic fitting functions

    International Nuclear Information System (INIS)

    Helm, J.L.

    1996-01-01

    The hyperbolic tangent function is used almost exclusively for computer assisted curve fitting of Charpy impact test data. Unfortunately, there is no physical basis to justify the use of this function and it cannot be generalized to test data that exhibits asymmetry. Using simple physical arguments, a semi-empirical model is derived and identified as a special case of the so called hyper-logistic equation. Although one solution of this equation is the hyperbolic tangent, other more physically interpretable solutions are provided. From the mathematics of the family of functions derived from the hyper-logistic equation, several useful generalizations are made such that asymmetric and wavy Charpy data can be physically interpreted

  6. Numerical modelling of Charpy-V notch test by local approach to fracture. Application to an A508 steel in the ductile-brittle transition range; Modelisation de l'essai Charpy par l'approche locale de la rupture. Application au cas de l'acier 16MND5 dans le domaine de transition

    Energy Technology Data Exchange (ETDEWEB)

    Tanguy, B

    2001-07-15

    Ferritic steels present a transition of the rupture mode which goes progressively of a brittle rupture (cleavage) to a ductile rupture when the temperature increases. The following of the difference of the transition temperature of the PWR vessel steel by the establishment of toughness curves makes of the Charpy test an integrating part of the monitoring of the French PWR reactors. In spite of the advantages which are adapted to it in particular its cost, the Charpy test does not allow to obtain directly a variable which characterizes a crack propagation resistance as for instance the toughness used for qualifying the mechanical integrity of a structure. This work deals with the establishment of the through impact strength-toughness in the transition range of the vessel steel: 16MND5 from a non-empirical approach based on the local approach of the rupture. The brittle rupture is described by the Beremin model (1983), which allows to describe the dispersion inherent in this rupture mode. The description of the brittle fissure is carried out by the GTN model (1984) and by the Rousselier model (1986). This last model has been modified in order to obtain a realistic description of the brittle damage in the case of fast solicitations and of local heating. The method proposed to determine the parameters of the damage models depends only of tests on notched specimens and of the inclusion data of the material. The behaviour is described by an original formulation parametrized in temperature which allows to describe all the tests carried out in this study. Before using this methodology, an experimental study of the behaviour and of the rupture modes of the steel 16MND5 has been carried out. From the toughness tests carried out in quasi-static and dynamical conditions, it has been revealed that this steel does not present important unwedging of its toughness curve due to the velocity effect. In the transition range, local heating of about 150 C have been measured in the root

  7. Charpy impact test pada kampas rem hybrid komposit phenolic resin matrik dengan penguat serbuk basalt-Alumina-kulit kerang

    Directory of Open Access Journals (Sweden)

    I N. G. Suma Wijaya

    2017-03-01

    Full Text Available Abstrak: Penelitian ini adalah difokuskan untuk mengamati ketahanan impact dari material kampas rem kendaraan bermotor. Kampasrem yang diujikan adalah kampas yang terbuat dari material hybrid komposit dengan penguat serbuk basalt – serbuk kulitkerang dan alumina dan pengikat phenolic resin. Material kampas rem hibrid komposit diproses melalui proses sinteringdengan penekanan 2 ton, temperatur 150ºC selama 30 menit. Tujuan penelitian adalah menginvestigasi kekuatan impact daripada bahan hybrid komposit untuk masing – masing variasi terhadap perlakuan impact charpy yang didasarkan pada standarASTM D6110–04. Pengujian dilakukan dengan menganalisa nilai energy yang mampu diserap oleh bahan akibat bebanimpact, selanjutnya patahan impact charpy dianalisa dengan SEM. Diperoleh hasil pengujian charpy impact untuk masing –masing variasi hybrid komposit adalah nilai kekuatan yang tinggi terjadi pada hibrid komposit variasi 2 (HK2 dengan nilai0,000339547 J/mm2, ini disebabkan karena mempunyai ikatan antara metrik dan basalt yang lebih kuat dan sempurnadibandingkan dengan hibrid komposit lainnya. Untuk nilai hibrid komposit variasi 1 (HK1 adalah 0,000304851 J/mm², hibridkomposit variasi 3 (HK3 adalah 0,000334516 J/mm², hibrid komposit variasi 4 (HK4 adalah 0,000325059 J/mm², hibridkomposit variasi 5 (HK5 adalah 0,0003327 J/mm². (2 Dari perbandingan antara kampas rem dipasaran dengan kampas remhibrid komposit maka didapat nilai kekuatannya berbeda pada hibrid komposit variasi 2 (HK2 dengan kampas pembanding(KP yang memiliki nilai kekuatannya lebih besar yaitu, 0,000374867 J/mm².Kata kunci : Kampas rem, Impact charpy, Hibrid komposit, Basalt, Aluminium, Kulit Kerang Abstract: This research is focused to observe the impact resistance of motor vehicles brake lining material. Brake tested are canvasmade of hybrid composite materials with basalt powder reinforced – seashells, alumina powder, and a phenolic resin matrix.Hybrid composite brake

  8. Critical applied stresses for a crack initiation from a sharp V-notch

    Directory of Open Access Journals (Sweden)

    L. Náhlík

    2014-10-01

    Full Text Available The aim of the paper is to estimate a value of the critical applied stress for a crack initiation from a sharp V-notch tip. The classical approach of the linear elastic fracture mechanics (LELM was generalized, because the stress singularity exponent differs from 0.5 in the studied case. The value of the stress singularity exponent depends on the V-notch opening angle. The finite element method was used for a determination of stress distribution in the vicinity of the sharp V-notch tip and for the estimation of the generalized stress intensity factor depending on the V-notch opening angle. Critical value of the generalized stress intensity factor was obtained using stability criteria based on the opening stress component averaged over a critical distance d from the V-notch tip and generalized strain energy density factor. Calculated values of the critical applied stresses were compared with experimental data from the literature and applicability of the LEFM concept is discussed.

  9. The Evolution of the Maine Lobster V-Notch Practice: Cooperation in a Prisoner's Dilemma Game

    Directory of Open Access Journals (Sweden)

    James Acheson

    2011-03-01

    Full Text Available The Maine lobster industry is experiencing record high catches because, in all probability, of an effective management program. One of the most important conservation measures is the V-notch program that allows fishermen to conserve proven breeding females by notching the tails of egg-bearing lobsters. Such marked lobsters may never be taken. Although thousands of lobster fishermen participate, it is a voluntary practice. The genesis of this practice is not easily explained, because V-notching poses a prisoner's dilemma problem that gives fishermen an incentive to avoid the practice. The most common explanations for ways to overcome prisoner's dilemma problems will not work in the case of the V-notch. An unusual combination of factors explains the V-notch program: (1 a strong belief among those in the industry that the V-notch is effective in conserving the lobster stock; (2 a low discount rate because the long-term gains from V-notching are higher than the one-time gain from defection; (3 a gain in reputation for those who V-notch. At the start of the 20th century, fishermen did not V-notch; by the end of the century, V-notching was common. We explain the change in strategies using a three-parameter evolutionary model that emphasizes the importance of culture change.

  10. Numerical modelling of Charpy-V notch test by local approach to fracture. Application to an A508 steel in the ductile-brittle transition range; Modelisation de l'essai Charpy par l'approche locale de la rupture. Application au cas de l'acier 16MND5 dans le domaine de transition

    Energy Technology Data Exchange (ETDEWEB)

    Tanguy, B

    2001-07-15

    Ferritic steels present a transition of the rupture mode which goes progressively of a brittle rupture (cleavage) to a ductile rupture when the temperature increases. The following of the difference of the transition temperature of the PWR vessel steel by the establishment of toughness curves makes of the Charpy test an integrating part of the monitoring of the French PWR reactors. In spite of the advantages which are adapted to it in particular its cost, the Charpy test does not allow to obtain directly a variable which characterizes a crack propagation resistance as for instance the toughness used for qualifying the mechanical integrity of a structure. This work deals with the establishment of the through impact strength-toughness in the transition range of the vessel steel: 16MND5 from a non-empirical approach based on the local approach of the rupture. The brittle rupture is described by the Beremin model (1983), which allows to describe the dispersion inherent in this rupture mode. The description of the brittle fissure is carried out by the GTN model (1984) and by the Rousselier model (1986). This last model has been modified in order to obtain a realistic description of the brittle damage in the case of fast solicitations and of local heating. The method proposed to determine the parameters of the damage models depends only of tests on notched specimens and of the inclusion data of the material. The behaviour is described by an original formulation parametrized in temperature which allows to describe all the tests carried out in this study. Before using this methodology, an experimental study of the behaviour and of the rupture modes of the steel 16MND5 has been carried out. From the toughness tests carried out in quasi-static and dynamical conditions, it has been revealed that this steel does not present important unwedging of its toughness curve due to the velocity effect. In the transition range, local heating of about 150 C have been measured in the root

  11. Impact strength of the uranium-6 weight percent niobium alloy between -1980 and +2000C

    International Nuclear Information System (INIS)

    Anderson, R.C.

    1981-09-01

    A study was conducted to determine if a ductile-to-brittle transition wxisted for the uranium-6 wt % niobium (U-6Nb) alloy. Standard V-notched Charpy bars were made from both solution-quenched and solution-quenched and aged U-6Nb alloy and were tested between -198 0 and +200 0 C. It was found that a sharp ductile-brittle transition does not exist for the alloy. A linear relationship existed between test temperature and impact strength, and the alloy retained a significant amount of impact strength even at very low temperatures. 9 figures

  12. Degradation of impact fracture during accelerated aging of weld metal on microalloyed steel

    International Nuclear Information System (INIS)

    Vargas-Arista, B.; Hallen, J. M.; Albiter, A.; Angeles-Chavez, C.

    2008-01-01

    The effect of accelerated aging on the toughness and fracture of the longitudinal weld metal on an API5L-X52 line pipe steel was evaluated by Charpy V-notch impact test, fracture analysis and transmission electron microscopy. Aging was performed at 250 degree centigrade for 100 to 1000 h. The impact results indicated a significant reduction in the fracture energy and impact toughness as a function of aging time, which were achieved by the scanning electron microscope fractography that showed a decrease in the vol fraction of microvoids by Charpy ductile failure with the aging time, which favored the brittle fracture by transgranular cleavage. The minimum vol fraction of microvoids was reached at 500 h due to the peak aged. The microstructural analysis indicated the precipitation of transgranular iron nano carbides in the aged specimens, which was related to the deterioration of toughness and change in the ductile to brittle behavior. (Author) 15 refs

  13. Dependence of hardness and impact energy on cooling time Δt8/5and temperature for S960QL

    OpenAIRE

    Samardžić, I.; Dunđer, M.; Vuherer, T.

    2015-01-01

    The paper deals with research into dependence of hardness and impact energy of thermal cycle simulated specimens of fine-grained structural steel S960QL on cooling time from 800 to 500 °C and on tested temperature. Results were obtained by measuring hardness of HV 10 and by experimental testing of Charpy notched tubes on instrumented Charpy hammer. Total impact energy, initiation energy and fracture propagation energy needed for occurrence of fracture is also elaborated. Key words:

  14. Three-dimensional vibrations of cylindrical elastic solids with V-notches and sharp radial cracks

    Science.gov (United States)

    McGee, O. G.; Kim, J. W.

    2010-02-01

    This paper provides free vibration data for cylindrical elastic solids, specifically thick circular plates and cylinders with V-notches and sharp radial cracks, for which no extensive previously published database is known to exist. Bending moment and shear force singularities are known to exist at the sharp reentrant corner of a thick V-notched plate under transverse vibratory motion, and three-dimensional (3-D) normal and transverse shear stresses are known to exist at the sharp reentrant terminus edge of a V-notched cylindrical elastic solid under 3-D free vibration. A theoretical analysis is done in this work utilizing a variational Ritz procedure including these essential singularity effects. The procedure incorporates a complete set of admissible algebraic-trigonometric polynomials in conjunction with an admissible set of " edge functions" that explicitly model the 3-D stress singularities which exist along a reentrant terminus edge (i.e., α>180°) of the V-notch. The first set of polynomials guarantees convergence to exact frequencies, as sufficient terms are retained. The second set of edge functions—in addition to representing the corner stress singularities—substantially accelerates the convergence of frequency solutions. This is demonstrated through extensive convergence studies that have been carried out by the investigators. Numerical analysis has been carried out and the results have been given for cylindrical elastic solids with various V-notch angles and depths. The relative depth of the V-notch is defined as (1- c/ a), and the notch angle is defined as (360°- α). For a very small notch angle (1° or less), the notch may be regarded as a "sharp radial crack." Accurate (four significant figure) frequencies are presented for a wide spectrum of notch angles (360°- α), depths (1- c/ a), and thickness ratios ( a/ h for plates and h/ a for cylinders). An extended database of frequencies for completely free thick sectorial, semi-circular, and

  15. Effects of Range of Stress and of Special Notches on Fatigue Properties of Aluminum Alloys Suitable for Airplane Propellers

    Science.gov (United States)

    Dolan, Thomas J

    1942-01-01

    Laboratory tests were made to obtain information on the load-resisting properties of X76S-T aluminum alloy when subjected to static, impact, and repeated loads. Results are presented from static-load test of unnotched specimens in tension and in torsion and of notched specimens in tension. Charpy impact values obtained from bend tests on notched specimens and tension impact values for both notched and unnotched specimens tested at several different temperatures are included. The endurance limits obtained from repeated bending fatigue tests made on three different types of testing machine are given for unnotched polished specimens, and the endurance limits of notched specimens subjected to six different ranges of bending stress are also reported. The results indicated that: (a) polished rectangular specimens had an endurance limit about 30 percent less than that obtained for round specimens; (b) a comparison of endurance limits obtained from tests on three different types of machine indicated that there was no apparent effect of speed of testing on the endurance limit for the range of speeds used (1,750 to 13,000 rpm). (c) the fatigue strength (endurance limit) of the X76S-T alloy was greatly decreased by the presence of a notch in the specimens; (d) no complete fractures of the entire specimens occurred in notched fatigue specimens when subjected to stress cycles for which the mean stress at the notch during the cycle was a compressive stress; for this test condition a microscopic cracking occurred near the root of the notch and was used as a criterion of failure of the specimen. (e) as the mean stress at the notch was decreased from a tensile (+) stress to a compressive (-) stress, it was found that the alternating stress that could be superimposed on the mean stress in the cycle without causing failure of the specimens was increased.

  16. Instrumented impact testing machine with reduced specimen oscillation effects

    International Nuclear Information System (INIS)

    Rintamaa, R.; Rahka, K.; Wallin, K.

    1984-07-01

    Owing to small and inexpensive specimens the Charpy impact test is widely used in quality control and alloy development. Limitations in power reactor survellance capsules it is also widely used for safety analysis purposes. Instrumenting the tup and computerizing data acquisition, makes dynamic fracture mechanics data measurement possible and convenient. However, the dynamic effects (inertia forces, specimen oscillations) in the impact test cause inaccuracies in the recorded load-time diagram and hence diminish the reliability of the calculated dynamic fracture mechanics parameters. To decrease inaccuracies a new pendulum type of instrumented impact test apparatus has been developed and constructed in the Metals Laboratory of the Technical Research Centre of Finland. This tester is based on a new principle involving inverted test geometry. The purpose of the geometry inversion is to reduce inertia load and specimen oscillation effects. Further, the new impact tester has some other novel features: e.g. the available initia impact energy is about double compared to the conventional standard (300 J) impact tester allowing the use of larger (10 x 20 x 110 mm) bend specimens than normal Charpy specimens. Also, the rotation asix in the three point bending is nearly stationary making COD-measurements possible. An experimental test series is described in which the inertia effects and specimen oscillations are compared in the conventional and new impact tester utilizing Charpy V-notch specimens. Comparison of the two test geometries is also made with the aid of an analytical model using finite element method (FEM) analysis. (author)

  17. Investigation on the Crack Initiation of V-Shaped Notch Tip in Precision Cropping

    Directory of Open Access Journals (Sweden)

    Lijun Zhang

    2014-01-01

    Full Text Available The crack initiation of V-shaped notch tip has a very important influence on the cross-section quality and the cropping time for every segment of metal bar in course of low stress precision cropping. By the finite element method, the influence of machining precision of V-shaped notch bottom corner on the crack initiation location is analyzed and it is pointed out that the crack initiation point locates in the place at the maximal equivalent stress change rate on V-shaped notch surface. The judgment criterion of the crack initiation direction is presented and the corresponding crack initiation angle can be calculated by means of the displacement extrapolation method. The factual crack initiation angle of the metal bar has been measured by using the microscopic measurement system. The formula of the crack initiation life of V-shaped notch tip is built, which mainly includes the stress concentration factor of V-shaped notch, the tensile properties of metal material, and the cyclic loading conditions. The experimental results show that the obtained theoretical analyses about the crack initiation location, the crack initiation direction, and the crack initiation time in this paper are correct. It is also shown that the crack initiation time accounts for about 80% of the cropping time for every segment of the metal bar.

  18. Rupture Predictions of Notched Ti-6Al-4V Using Local Approaches

    Directory of Open Access Journals (Sweden)

    Mirco Peron

    2018-04-01

    Full Text Available Ti-6Al-4V has been extensively used in structural applications in various engineering fields, from naval to automotive and from aerospace to biomedical. Structural applications are characterized by geometrical discontinuities such as notches, which are widely known to harmfully affect their tensile strength. In recent years, many attempts have been done to define solid criteria with which to reliably predict the tensile strength of materials. Among these criteria, two local approaches are worth mentioning due to the accuracy of their predictions, i.e., the strain energy density (SED approach and the theory of critical distance (TCD method. In this manuscript, the robustness of these two methods in predicting the tensile behavior of notched Ti-6Al-4V specimens has been compared. To this aim, two very dissimilar notch geometries have been tested, i.e., semi-circular and blunt V-notch with a notch root radius equal to 1 mm, and the experimental results have been compared with those predicted by the two models. The experimental values have been estimated with low discrepancies by either the SED approach and the TCD method, but the former results in better predictions. The deviations for the SED are in fact lower than 1.3%, while the TCD provides predictions with errors almost up to 8.5%. Finally, the weaknesses and the strengths of the two models have been reported.

  19. Statistical evaluation of fracture characteristics of RPV steels in the ductile-brittle transition temperature region

    International Nuclear Information System (INIS)

    Kang, Sung Sik; Chi, Se Hwan; Hong, Jun Hwa

    1998-01-01

    The statistical analysis method was applied to the evaluation of fracture toughness in the ductile-brittle transition temperature region. Because cleavage fracture in steel is of a statistical nature, fracture toughness data or values show a similar statistical trend. Using the three-parameter Weibull distribution, a fracture toughness vs. temperature curve (K-curve) was directly generated from a set of fracture toughness data at a selected temperature. Charpy V-notch impact energy was also used to obtain the K-curve by a K IC -CVN (Charpy V-notch energy) correlation. Furthermore, this method was applied to evaluate the neutron irradiation embrittlement of reactor pressure vessel(RPV) steel. Most of the fracture toughness data were within the 95 percent confidence limits. The prediction of a transition temperature shift by statistical analysis was compared with that from the experimental data. (author)

  20. Effect of aging on impact properties of ASTM A890 Grade 1C super duplex stainless steel

    International Nuclear Information System (INIS)

    Martins, Marcelo; Forti, Leonardo Rodrigues Nogueira

    2008-01-01

    Super duplex stainless steels in the solution annealed condition are thermodynamically metastable systems which, when exposed to heat, present a strong tendency to 'seek' the most favorable thermodynamic condition. The main purpose of this study was to characterize the microstructure of a super duplex stainless steel in the as cast and solution annealed conditions, and to determine the influence of aging heat treatments on its impact strength, based on Charpy impact tests applied to V-notched test specimens. The sigma phase was found to begin precipitating at heat treatment temperatures above 760 deg. C and to dissolve completely only above 1040 deg. C, with the highest peak concentration of this phase appearing at close to 850 deg. C. Heat treatments conducted at temperatures of 580 deg. C to 740 deg. C led to a reduction of the energy absorbed in the Charpy impact test in response to the precipitation of a particulate phase with particle sizes ranging from 0.5 μm to 1.0 μm, with a chromium and iron-rich chemical composition

  1. Degradation of impact fracture during accelerated aging of weld metal on microalloyed steel; Degradacion de la tenacidad al impacto durante el envejecimiento acelerado de soldadura en acero microaleado

    Energy Technology Data Exchange (ETDEWEB)

    Vargas-Arista, B.; Hallen, J. M.; Albiter, A.; Angeles-Chavez, C.

    2008-07-01

    The effect of accelerated aging on the toughness and fracture of the longitudinal weld metal on an API5L-X52 line pipe steel was evaluated by Charpy V-notch impact test, fracture analysis and transmission electron microscopy. Aging was performed at 250 degree centigrade for 100 to 1000 h. The impact results indicated a significant reduction in the fracture energy and impact toughness as a function of aging time, which were achieved by the scanning electron microscope fractography that showed a decrease in the vol fraction of microvoids by Charpy ductile failure with the aging time, which favored the brittle fracture by transgranular cleavage. The minimum vol fraction of microvoids was reached at 500 h due to the peak aged. The microstructural analysis indicated the precipitation of transgranular iron nano carbides in the aged specimens, which was related to the deterioration of toughness and change in the ductile to brittle behavior. (Author) 15 refs.

  2. Fracture Toughness Evaluation of Kori-1 RPV Beltline Weld for a Long-Term Operation

    International Nuclear Information System (INIS)

    Lee, Bong-Sang; Kim, Min-Chul; Ahn, Sang-Bok; Kim, Byung-Chul; Hong, Jun-Hwa

    2007-01-01

    Irradiation embrittlement of RPV (reactor pressure vessel) material is the most important aging issue for a long-term operation of nuclear power plants. KORI unit 1, which is the first PWR in Korea, is approaching its initial licensing life of 30 years. In order to operate the reactor for another 10 years and more, it should be demonstrated that the irradiation embrittlement of the reactor will be adequately managed by ensuring that the fracture toughness properties have a certain level of the safety margin. The current regulation requires Charpy V-notch impact data through conventional surveillance tests. It is based on the assumption that Charpy impact test results are well correlated with the fracture toughness properties of many engineering steels. However, Charpy V-notch impact data may not be adequate to estimate the fracture toughness of certain materials, such as Linde 80 welds. During the last decade, a tremendous number of fracture toughness data on many RPV steels have been produced in accordance with the new standard test method, the so-called master curve method. ASTM E1921 represents a revolutionary advance in characterizing fracture toughness of RPV steels, since it permits establishing the ductile to brittle transition portion of the fracture toughness curve with direct measurements on a relatively small number of relatively small specimens, such as pre-cracked Charpy specimens. Actual fracture toughness data from many different RPV steels revealed that the Charpy test estimations are generally conservative with the exception of a few cases. Recent regulation codes in USA permit the master curve fracture toughness methodology in evaluating an irradiation embrittlement of commercial nuclear reactor vessels

  3. Fundamental study of crack initiation and propagation

    International Nuclear Information System (INIS)

    Norris, D.M. Jr.; Reaugh, J.E.; Moran, B.; Quinones, D.F.; Wilkins, M.L.

    1977-01-01

    Objective is to determine the fracture toughness of A533B-1 steel by computer modeling Charpy V-notch tests. A computer model of ductile fracture was developed that predicts fracture initiation. The model contains a set of material-dependent parameters obtained by computer simulations of small specimen tests. The computer calculations give detailed stress and strain histories up to the time of fracture, which are used to determine the model parameter values. The calibrated fracture model, that correctly predicts fracture initiation (and initiation energy) in the Charpy specimen, may then be used to simulate tests of accepted fracture-toughness specimens and hence obtain fracture toughness. The model parameters were calibrated to predict fracture in four different test specimens: two different notched-tension specimens, a simple tension specimen, and a precracked compact-tension specimen. The model was then used in a computer simulation of the Charpy V-notch specimen to initiate and advance a flat fracture. Results were compared with interrupted Charpy tests. Calibration of the model for two additional heat treatments of A533B-1 steel is in progress

  4. Computer aided instrumented Charpy test applied dynamic fracture toughness evaluation system

    International Nuclear Information System (INIS)

    Kobayashi, Toshiro; Niinomi, Mitsuo

    1986-01-01

    Micro computer aided data treatment system and personal computer aided data analysis system were applied to the traditional instrumented Charpy impact test system. The analysis of Charpy absorbed energy (E i , E p , E t ) and load (P y , P m ), and the evaluation of dynamic toughness through whole fracture process, i.e. J Id , J R curve and T mat was examined using newly developed computer aided instrumented Charpy impact test system. E i , E p , E t , P y and P m were effectively analyzed using moving average method and printed out automatically by micro computer aided data treatment system. J Id , J R curve and T mat could be measured by stop block test method. Then, J Id , J R curve and T mat were effectively estimated using compliance changing rate method and key curve method on the load-load point displacement curve of single fatigue cracked specimen by personal computer aided data analysis system. (author)

  5. Fundamental study of crack initiation and propagation. Annual progress report, March 1976--March 1977

    International Nuclear Information System (INIS)

    Norris, D.M. Jr.

    1977-01-01

    Ductile fracture in nuclear pressure vessel steel was characterized using a computer model of material damage. The model predicts crack initiation and growth and contains constants that are set by computer simulation of the following fracture tests: the simple tension test, the circumferentially notched round tension test, the blunt-notched compact tension test, and the Charpy V-notch test. The simulations provide the stress and strain states of these tests at fracture. The major goal of our characterization program is to determine the correlation between Charpy toughness and fracture toughness

  6. Comparative study on Charpy specimen reconstitution techniques

    International Nuclear Information System (INIS)

    Bourdiliau, B.; Decroix, G.-M.; Averty, X.; Wident, P.; Bienvenu, Y.

    2011-01-01

    Highlights: → Welding processes are used to reconstitute previously tested Charpy specimens. → Stud welding is preferred for a quick installation, almost immediately operational. → Friction welding produces better quality welds, but requires a development effort. - Abstract: Reconstitution techniques are often used to allow material from previously fractured Charpy-V specimens to be reused for additional experiments. This paper presents a comparative experimental study of various reconstitution techniques and evaluates the feasibility of these methods for future use in shielded cells. The following techniques were investigated: arc stud welding, 6.0 kW CO 2 continuous wave laser welding, 4.5 kW YAG continuous wave laser welding and friction welding. Subsize Charpy specimens were reconstituted using a 400 W YAG pulsed wave laser. The best result was obtained with arc stud welding; the resilience of the reconstituted specimens and the load-displacement curves agreed well with the reference specimens, and the temperature elevation caused by the welding process was limited to the vicinity of the weld. Good results were also obtained with friction welding; this process led to the best quality welds. Laser welding seems to have affected the central part of the specimens, thus leading to different resilience values and load-displacement curves.

  7. Observations of the severity of notch-root radius in initiation of subcritical crack growth

    International Nuclear Information System (INIS)

    Reuter, W.G.; Eiholzer, C.R.; Tupper, M.A.

    1981-01-01

    Slow bend tests were conducted on Charpy specimens containing precracks or machined notches of 0.10 or 0.25 mm radius. The test specimens were fabricated from three heats of annealed Type 304 stainless steel. The purpose of these tests was to examine the effects of notch root radius, in very ductile materials, on initiation of subcritical crack growth. In addition, it was intended to establish the critical values of J, COD, etc. for the single-edge notch specimen for comparison with results obtained from specimens containing surface flaws. This paper will briefly describe only those results of the calculation for J. The tests were monitored by acoustic emission to identify the load corresponding to initiation of subcritical crack growth, by a crack-opening displacement gage (COD), by cross-head displacement, and by stop-action photography

  8. Recent advances on Charpy specimen reconstitution techniques

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Arnaldo H.P.; Lobo, Raquel M.; Miranda, Carlos Alexandre J., E-mail: aandrade@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2017-07-01

    Charpy specimen reconstitution is widely used around the world as a tool to enhance or supplement surveillance programs of nuclear reactor pressure vessels. The reconstitution technique consists in the incorporation of a small piece from a previously tested specimen into a compound specimen, allowing to increase the number of tests. This is especially important if the available materials is restricted and fracture mechanics parameter have to be determined. The reconstitution technique must fulfill some demands, among them tests results like the original standard specimens and the loaded material of the insert must not be influenced by the welding and machining procedure. It is known that reconstitution of Charpy specimens may affect the impact energy in a consequence of the constraint of plastic deformation by the hardened weldment and HAZ. This paper reviews some recent advances of the reconstitution technique and its applications. (author)

  9. Recent advances on Charpy specimen reconstitution techniques

    International Nuclear Information System (INIS)

    Andrade, Arnaldo H.P.; Lobo, Raquel M.; Miranda, Carlos Alexandre J.

    2017-01-01

    Charpy specimen reconstitution is widely used around the world as a tool to enhance or supplement surveillance programs of nuclear reactor pressure vessels. The reconstitution technique consists in the incorporation of a small piece from a previously tested specimen into a compound specimen, allowing to increase the number of tests. This is especially important if the available materials is restricted and fracture mechanics parameter have to be determined. The reconstitution technique must fulfill some demands, among them tests results like the original standard specimens and the loaded material of the insert must not be influenced by the welding and machining procedure. It is known that reconstitution of Charpy specimens may affect the impact energy in a consequence of the constraint of plastic deformation by the hardened weldment and HAZ. This paper reviews some recent advances of the reconstitution technique and its applications. (author)

  10. 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

  11. Influence of phase transformations on the asymptotic residual stress distribution arising near a sharp V-notch tip

    International Nuclear Information System (INIS)

    Ferro, P

    2012-01-01

    In this work, the residual stress distribution induced by the solidification and cooling of a fusion zone in the vicinity of a sharp V-notch tip is investigated. The intensity of the residual asymptotic stress fields, quantified by the notch stress intensity factors, was studied for two different V-notch specimen geometries under generalized plane-strain conditions. In order to analyze the influence of phase transformations on the obtained results, simulations with and without the effects of phase transformation were carried out on ASTM SA 516 steel plates. Thanks to the possibilities of numerical modelling, additional analyses were performed without taking into account the transformation plasticity phenomenon. It was found that phase transformation effects (both volume change and transformation plasticity) have a great influence on the intensity and sign of the asymptotic stress fields at the sharp V-notch tips. This result is believed to be very important for the correct numerical determination (and future applications) of notch stress intensity factors resulting from asymptotic residual stress distributions induced by transient thermal loads. The analyses were performed with the finite element code SYSWELD. (paper)

  12. Study of crack propagation mechanisms during Charpy impact toughness tests on both equiaxed and lamellar microstructures of Ti–6Al–4V titanium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Buirette, Christophe, E-mail: christophe.buirette@ensiacet.fr [Institut Carnot CIRIMAT, ENSIACET, 4 allée Emile Monso, 31030 Toulouse (France); Huez, Julitte, E-mail: julitte.huez@ensiacet.fr [Institut Carnot CIRIMAT, ENSIACET, 4 allée Emile Monso, 31030 Toulouse (France); Gey, Nathalie, E-mail: Nathalie.gey@univ-lorraine.fr [Laboratoire d’Etude des Microstructures et de Mécanique des Matériaux (LEM3), UMR CNRS 7239, Université de Lorraine, Île du Saulcy, 57045 METZ Cedex 1 (France); DAMAS, Laboratory of Excellence on Design of Alloy Metals for Low-Mass Structures, Université de Lorraine (France); Vassel, Alain, E-mail: alain.vassel@titane.asso.fr [Association Française du Titane, 16 quai Ernest Renaud, BP 70515, 44105 Nantes Cedex 4 (France); Andrieu, Eric, E-mail: eric.andrieu@ensiacet.fr [Institut Carnot CIRIMAT, ENSIACET, 4 allée Emile Monso, 31030 Toulouse (France)

    2014-11-17

    The impact toughness of two highly textured rolled plates of Ti–6Al–4V alloy with an α equiaxed and an α lamellar microstructures has been investigated. The results show a strong anisotropy of the fracture energy for both materials and underline that a coincidence of the prismatic planes with the shear bands at the notch tip is favorable for higher fracture energies. Moreover, it is pointed out, as it was already done by previous studies, that the α lamellar microstructure presents higher fracture energy than the α equiaxed one. Thanks to electron back scattering diffraction, and tensile tests, local microstructure heterogeneities, called macrozones, have been observed and characterized. Their size depends on microstructure element and is larger for α lamellar microstructure than for the α equiaxed. High strain is localized on the macrozones favorably oriented for prismatic slip with respect to the direction of impact and leads to a particular dimple free zone on the fracture surface. The contribution of these macrozones in the fracture behavior, and more precisely on the crack propagation rate was evaluated; thus the effects of the macroscopic texture and of the microstructure element on the impact toughness are discussed separately.

  13. Precipitation and impact toughness of Nb–V stabilised 18Cr–2Mo ferritic stainless steel during isothermal aging

    International Nuclear Information System (INIS)

    Han, Jian; Li, Huijun; Barbaro, Frank; Jiang, Laizhu; Zhu, Zhixiong; Xu, Haigang; Ma, Li

    2014-01-01

    The effect of isothermal aging on precipitation behaviour and Charpy impact toughness of Nb–V stabilised 18Cr–2Mo ferritic stainless steel was investigated by means of Thermo-Calc prediction, scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Charpy impact toughness testing. The results show that, niobium, vanadium carbides and nitrides, Fe 2 Nb (Laves phase) and Cr 23 C 6 formed after 2 h aging at 800 °C, and the equilibrium solvus temperature of Fe 2 Nb phase increases to above 750 °C, higher than the calculated temperature (730 °C) using Thermo-Calc. After isothermal aging at 750–950 °C, 2 h aging resulted in a decrease in toughness due to the formation of precipitation, especially (Nb,V)(C,N) and Fe 2 Nb. When isothermally aged at 800 °C for up to 24 h, the coarsening rate of Fe 2 Nb particle is much higher than that of (Nb,V)(C,N), and the impact toughness of the steel is dependent on quantity and sizes of (Nb,V)(C,N) and Fe 2 Nb particles

  14. Precipitation and impact toughness of Nb–V stabilised 18Cr–2Mo ferritic stainless steel during isothermal aging

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jian, E-mail: jh595@uowmail.edu.au [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Li, Huijun [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Barbaro, Frank [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); CBMM Technology Suisse, 14, Rue du Rhone, Geneve 1204 (Switzerland); Jiang, Laizhu [Baoshan Iron and Steel Co., Ltd., Shanghai 200431 (China); Zhu, Zhixiong [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Xu, Haigang; Ma, Li [Baoshan Iron and Steel Co., Ltd., Shanghai 200431 (China)

    2014-08-26

    The effect of isothermal aging on precipitation behaviour and Charpy impact toughness of Nb–V stabilised 18Cr–2Mo ferritic stainless steel was investigated by means of Thermo-Calc prediction, scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Charpy impact toughness testing. The results show that, niobium, vanadium carbides and nitrides, Fe{sub 2}Nb (Laves phase) and Cr{sub 23}C{sub 6} formed after 2 h aging at 800 °C, and the equilibrium solvus temperature of Fe{sub 2}Nb phase increases to above 750 °C, higher than the calculated temperature (730 °C) using Thermo-Calc. After isothermal aging at 750–950 °C, 2 h aging resulted in a decrease in toughness due to the formation of precipitation, especially (Nb,V)(C,N) and Fe{sub 2}Nb. When isothermally aged at 800 °C for up to 24 h, the coarsening rate of Fe{sub 2}Nb particle is much higher than that of (Nb,V)(C,N), and the impact toughness of the steel is dependent on quantity and sizes of (Nb,V)(C,N) and Fe{sub 2}Nb particles.

  15. Relationships between Charpy impact shelf energies and upper shelf Ksub(IC) values for reactor pressure vessel steels

    International Nuclear Information System (INIS)

    Witt, F.J.

    1983-01-01

    Charpy shelf data and lower bound estimates of Ksub(IC) shelf data for the same steels and test temperatures are given. Included are some typical reactor pressure vessel steels as well as some less tough or degraded steels. The data were evaluated with shelf estimates of Ksub(IC) up to and exceeding 550 MPa√m. It is shown that the high shelf fracture toughness representative of tough reactor pressure vessel steels may be obtained from a knowledge of the Charpy shelf energies. The toughness transition may be obtained either by testing small fracture toughness specimens or by Charpy energy indexing. (U.K.)

  16. The effect of microstructural change on the Charpy impact properties of the high-strength ferritic/martensitic steel (PNC-FMS) irradiated in JOYO/MARICO-1

    International Nuclear Information System (INIS)

    Yano, Yasuhide; Akasaka, Naoaki; Yoshitake, Tsunemitsu; Abe, Yasuhiro

    2004-03-01

    It is well known that the irradiation embrittlement is one of the most important issues to apply ferritic steels for FBR core materials, although ferritic steels have been considered to be candidate core materials of the commercialized FBR core material because of their superior swelling resistance. In order to evaluate the effects of microstructural changes during irradiation on the Charpy impact properties of the high-strength ferritic/martensitic steel (PNC-FMS), microstructural observations were performed with transmission electron microscopy on ruptured halves of the half-sized Charpy specimens of PNC-FMS irradiated in the JOYO/MARICO-1. The results obtained in this study are as follows: (1) There was remarkable disappearance of the lath of martensite in the samples irradiated at 650degC, although there was no significant change in microstructures, especially the lath of martensite between the samples irradiated at 500degC and unirradiated. The disappearance of martensitic lath in the samples irradiated at 650degC was larger than that of the samples thermally aged at 650degC. (2) The ductile-brittle transition temperature (DBTT) of irradiated PNC-FMS is judged to increase with the disappearance of martensitic lath and to decrease with the recovery in dislocations. (3) The decrease in the upper shelf energy (USE) of irradiated PNC-FMS is significantly accompanied by the change of precipitation behavior. (4) The Charpy impact properties and microstructures of PNC-FMS irradiated at 500degC were superior under these irradiation conditions. In future, it is necessary to establish how to evaluate Charpy impact properties in a high fluence region, based on theoretical methods introduced from the data gained in low fluence experiments, in addition to expanding the data area widely. (author)

  17. Grain size and temperature influence on the toughness of a CuAlBe shape memory alloy

    International Nuclear Information System (INIS)

    Albuquerque, Victor Hugo C. de; Melo, Tadeu Antonio de A; Gomes, Rodinei M.; Lima, Severino Jackson G. de; Tavares, Joao Manuel R.S.

    2010-01-01

    Research highlights: → This work evaluated the capacity of a CuAlBe alloy to absorb energy until rupture. → The V-notch Charpy test was adopted at -150, -100, -50, 0, 50, 100 and 150 deg. C. → Charpy tests were complemented by DSC, DSC with optical microscope and by SEM. → First work to analyze the toughness of a CuAlBe alloy based on the Charpy test. → The results are of relevant value to enhance the understanding of the CuAlBe alloy. - Abstract: This work is a study of the influence of grain size and temperature on the toughness of CuAlBe shape memory alloys with (CuAlBeNbNi) and without NbNi (CuAlBe) grain refiner elements. The toughness analysis was based on the V-notch Charpy impact test under temperatures of -150, -100, -50, 0, 50, 100 and 150 deg. C. A statistical analysis of the results led to the conclusion that the toughness of both alloys was influenced by temperature and grain size. The CuAlBeNbNi alloy absorbed higher impact energy than the CuAlBe alloy showing that the refining elements improved the toughness of the alloy. To confirm and complement these findings, the fracture surfaces were evaluated by stereomicroscopy. Smooth homogeneous surfaces and rough heterogonous surfaces were detected for the CuAlBeNbNi and CuAlBe alloys, respectively. Predominately brittle zones were confirmed by scanning electron microscopy in both alloys. Furthermore, to determine the phase transformation temperatures and the associated microstructures, the alloys were assessed by conventional differential scanning calorimetry (DSC) and DSC with optical microscopy.

  18. Grain size and temperature influence on the toughness of a CuAlBe shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Albuquerque, Victor Hugo C. de, E-mail: victor.albuquerque@fe.up.pt [Universidade Federal da Paraiba (UFPB), Departamento de Engenharia Mecanica (DEM), Laboratorio de Solidificacao Rapida LSR, Cidade Universitaria, S/N 58059-900 Joao Pessoa, PB (Brazil); Melo, Tadeu Antonio de A, E-mail: tadeu@lsr.ct.ufpb.br [Universidade Federal da Paraiba (UFPB), Departamento de Engenharia Mecanica (DEM), Laboratorio de Solidificacao Rapida LSR, Cidade Universitaria, S/N 58059-900 Joao Pessoa, PB (Brazil); Gomes, Rodinei M., E-mail: gomes@lsr.ct.ufpb.br [Universidade Federal da Paraiba (UFPB), Departamento de Engenharia Mecanica (DEM), Laboratorio de Solidificacao Rapida LSR, Cidade Universitaria, S/N 58059-900 Joao Pessoa, PB (Brazil); Lima, Severino Jackson G. de, E-mail: jackson@lsr.ct.ufpb.br [Universidade Federal da Paraiba (UFPB), Departamento de Engenharia Mecanica (DEM), Laboratorio de Solidificacao Rapida LSR, Cidade Universitaria, S/N 58059-900 Joao Pessoa, PB (Brazil); Tavares, Joao Manuel R.S., E-mail: tavares@fe.up.pt [Faculdade de Engenharia da Universidade do Porto (FEUP), Departamento de Engenharia Mecanica (DEMec)/Instituto de Engenharia Mecanica e Gestao Industrial INEGI, Rua Dr. Roberto Frias, S/N 4200-465 Porto (Portugal)

    2010-11-25

    Research highlights: {yields} This work evaluated the capacity of a CuAlBe alloy to absorb energy until rupture. {yields} The V-notch Charpy test was adopted at -150, -100, -50, 0, 50, 100 and 150 deg. C. {yields} Charpy tests were complemented by DSC, DSC with optical microscope and by SEM. {yields} First work to analyze the toughness of a CuAlBe alloy based on the Charpy test. {yields} The results are of relevant value to enhance the understanding of the CuAlBe alloy. - Abstract: This work is a study of the influence of grain size and temperature on the toughness of CuAlBe shape memory alloys with (CuAlBeNbNi) and without NbNi (CuAlBe) grain refiner elements. The toughness analysis was based on the V-notch Charpy impact test under temperatures of -150, -100, -50, 0, 50, 100 and 150 deg. C. A statistical analysis of the results led to the conclusion that the toughness of both alloys was influenced by temperature and grain size. The CuAlBeNbNi alloy absorbed higher impact energy than the CuAlBe alloy showing that the refining elements improved the toughness of the alloy. To confirm and complement these findings, the fracture surfaces were evaluated by stereomicroscopy. Smooth homogeneous surfaces and rough heterogonous surfaces were detected for the CuAlBeNbNi and CuAlBe alloys, respectively. Predominately brittle zones were confirmed by scanning electron microscopy in both alloys. Furthermore, to determine the phase transformation temperatures and the associated microstructures, the alloys were assessed by conventional differential scanning calorimetry (DSC) and DSC with optical microscopy.

  19. Detection of ductile crack initiation by acoustic emission testing

    International Nuclear Information System (INIS)

    Richter, H.; Boehmert, J.; Viehrig, H.W.

    1998-08-01

    A Charpy impact test equipment is described permitting simultaneous measurement of impact force, crack tip opening, acoustic emissions and magnetic emissions. The core of the equipment is an inverted pendulum ram impact testing machine and the tests have been performed with laterally notched, pre-fatigue ISO-V specimens made of steels of various strength and toughness properties. The tests are intended to ascertain whether the acoustic emission method is suitable for detecting steady crack initiation in highly ductile steels. (orig./CB) [de

  20. Effect of delaminations on improvement of notch toughness at low temperatures

    International Nuclear Information System (INIS)

    Zhou, W.; Loh, N.L.

    1996-01-01

    The notched-bar impact test is often used to assess the notch toughness of engineering materials. The principle of the test is that a material absorbs a certain amount of energy when it breaks; the energy thus absorbed is an indication of the material's resistance to impact fracture. If the material is brittle, it breaks easily with a small amount of absorbed energy. If it is tough, it will absorb more energy to fracture. It has been well recognized that most engineering materials undergo a transition from notch tough to notch brittle behavior when the temperature is reduced. In the present study, however, an abnormal trend in the transition behavior was found for an austenitic stainless steel. V-notched specimens of the steel were tested under impact loading in a wide temperature range from -196 C to room temperature. Contrary to expectation, the impact energy values obtained at low temperatures were found to be much higher than those obtained at room temperature, indicating that the steel became tougher rather than more brittle when the test temperature was lowered. This intriguing phenomenon cannot be explained simply according to the tensile stress fracture criterion. Strong evidence has been obtained in the present study to show that the improvement of notch toughness at low temperatures is caused by delaminations

  1. Irradiation Effects at 160-240 deg C in Some Swedish Pressure Vessel Steels

    Energy Technology Data Exchange (ETDEWEB)

    Grounes, M [AB Atomenergi, Nykoeping (Sweden); Myers, H P [Chalmers Institute of Technology, Goeteborg (Sweden); Hannerz, N E [Motala Verkstads AB, Motala (Sweden)

    1967-09-15

    Tensile specimens, Charpy impact specimens and miniature impact specimens of six steels in different conditions were irradiated to 2.8 x 10{sup 18} and 5.6 x 10{sup 18} n/cm{sup 2} (> 1 MeV) at 160-240 deg C. The steels investigated were SIS 142103, 2103/R3, NO 345, Fortiweld, Fortiweld HS and OK 54 P. There is no correlation between the increase in transition temperature and initial transition temperature. However, changes in strength and ductility can be correlated to the initial yield strength. The increases in transition temperature due to strain aging and irradiation are approximately additive. The irradiation-induced changes in 2103/R3 and Fortiweld HS steels do not vary with position in the thickness of the plate. Different tempering treatments in Fortiweld HS steel do not change the extent of irradiation effects. Normal Charpy V-notch impact specimens and miniature specimens give the same irradiation-induced increase in transition temperature.

  2. Irradiation Effects at 160-240 deg C in Some Swedish Pressure Vessel Steels

    International Nuclear Information System (INIS)

    Grounes, M.; Myers, H.P.; Hannerz, N.E.

    1967-09-01

    Tensile specimens, Charpy impact specimens and miniature impact specimens of six steels in different conditions were irradiated to 2.8 x 10 18 and 5.6 x 10 18 n/cm 2 (> 1 MeV) at 160-240 deg C. The steels investigated were SIS 142103, 2103/R3, NO 345, Fortiweld, Fortiweld HS and OK 54 P. There is no correlation between the increase in transition temperature and initial transition temperature. However, changes in strength and ductility can be correlated to the initial yield strength. The increases in transition temperature due to strain aging and irradiation are approximately additive. The irradiation-induced changes in 2103/R3 and Fortiweld HS steels do not vary with position in the thickness of the plate. Different tempering treatments in Fortiweld HS steel do not change the extent of irradiation effects. Normal Charpy V-notch impact specimens and miniature specimens give the same irradiation-induced increase in transition temperature

  3. Notching on cancer’s door: Notch signaling in brain tumors

    Directory of Open Access Journals (Sweden)

    Marcin eTeodorczyk

    2015-01-01

    Full Text Available Notch receptors play an essential role in the regulation of central cellular processes during embryonic and postnatal development. The mammalian genome encodes for four Notch paralogs (Notch 1-4, which are activated by three Delta-like (Dll1/3/4 and two Serrate-like (Jagged1/2 ligands. Further, non-canonical Notch ligands such as EGFL7 have been identified and serve mostly as antagonists of Notch signaling. The Notch pathway prevents neuronal differentiation in the central nervous system by driving neural stem cell maintenance and commitment of neural progenitor cells into the glial lineage. Notch is therefore often implicated in the development of brain tumors, as tumor cells share various characteristics with neural stem and progenitor cells. Notch receptors are overexpressed in gliomas and their oncogenicity has been confirmed by gain- and loss-of-function studies in vitro and in vivo. To this end, special attention is paid to the impact of Notch signaling on stem-like brain tumor-propagating cells as these cells contribute to growth, survival, invasion and recurrence of brain tumors. Based on the outcome of ongoing studies in vivo, Notch-directed therapies such as γ secretase inhibitors and blocking antibodies have entered and completed various clinical trials. This review summarizes the current knowledge on Notch signaling in brain tumor formation and therapy.

  4. Influence of Mo addition on the tempered properties of 13Cr martensitic stainless steel

    International Nuclear Information System (INIS)

    Jung, Byong Ho; Ahn, Yong Sik

    1998-01-01

    In order to investigate the effect of Mo addition on the mechanical properties of 13Cr-0.2C martensitic stainless steel, tensile test and Charpy V-notch test were performed after tempering at the temperature range of 200∼700 .deg. C following austenitizing at 1100 .deg. C. The yield strength and hardness of the steel were increased with the increase of Mo content at all tempering conditions, because Mo causes retardation of precipitation and coarsening of carbides and solid solution strengthening of matrix. Except 500 .deg. C of tempering temperature, the Charpy impact energy was significantly increased with Mo content and showed the highest value at 1.5 wt% addition. The increase of impact energy of the steel containing Mo is thought to be caused by δ-ferrite formed in the tempered martensitic matrix. At 500 .deg. C tempering, Charpy impact energy was decreased drastically due to temper embrittlement and it was not possible to prevent it even though Mo was added up to 1.5 wt%

  5. Effect of neutron irradiation on the impact properties of A533B steel

    International Nuclear Information System (INIS)

    Schubert, L.E.; Kumar, A.S.; Rosinski, S.T.; Hamilton, M.L.

    1994-01-01

    A new methodology is proposed to correlate the upper shelf energy (USE) of full size and subsize Charpy specimens of a nuclear reactor pressure vessel plate material, ASTM type A 533 Grade B (A533B) having a low USE (USE 19 n/cm 2 (E > 1 MeV) by 78 degree, 83 degree, and 70 degree C for full, half, and third size specimens, respectively. These shifts in DBTT appeared to be independent of specimen size and notch geometry

  6. Charpy impact behavior of manganese-stabilized martensitic steels

    International Nuclear Information System (INIS)

    Hu, W.L.; Gelles, D.S.

    1986-05-01

    Tests were conducted to evaluate the irradiation-induced shift in ductile-to-brittle transition behavior of two manganese stabilized martensitic steels. Miniature Charpy specimens were fabricated from two heats of steel similar in composition to HT-9 but with 0.1% C and Mn contents ranging from 3.3 to 6.6.%. The 3.3% Mn steel showed a transition temperature similar to that of HT-9 in both the unirradiated condition and in specimens irradiated to 11.3 dpa. The steel containing 6.6% Mn exhibited a higher transition temperature after irradiation than the steel containing 3.3% Mn. The upper shelf energy (USE) after irradiation for the manganese stabilized alloys was much higher than for HT-9. 6 refs., 3 figs., 2 tabs

  7. Fracture toughness evaluation of small notched specimen in consideration of notch effect and loading rate

    International Nuclear Information System (INIS)

    Lee, Baik Woo; Kwon, Dong Il; Jang, Jae Il

    2000-01-01

    Notch effect and loading rate dependency on fracture toughness were considered when evaluating fracture toughness of small notched specimens using the instrumented impact test. Notch effect was analyzed into stress redistribution effect and stress relaxation with a viewpoint of stress triaxiality. Stress redistribution effect was corrected by introducing effective crack length, which was the sum of actual crack length and plastic zone size. Stress relaxation effect was also corrected using elastic stress concentration factor, which would decrease if plastic deformation occurred. As a result, corrected fracture toughness of the notched specimen was very consistent with the reference fracture toughness obtained using precracked specimen. In addition, limiting notch root radius, below which fracture toughness was independent of notch radius, was observed and discussed. Loading rate dependency on fracture toughness, which was obtained from the static three point bending test and the instrumented impact test, was also discussed with stress field in plastic zone ahead of a notch and fracture based on stress control mechanism. (author)

  8. On the use of the instrumented Charpy-V impact signal for assessment of RPVS embrittlement

    Energy Technology Data Exchange (ETDEWEB)

    Fabry, A.; Van Walle, E.; Van de Velde, J.; Chauoadi, R.; Puzzolante, J.L.; Van Ransbeeck, Th.; Verstrepen, A.

    1995-12-01

    In the context of LWR pressure vessel surveillance, the significance of the Cv notch impact test instrumented by strain gages has been revised. The load diagram (general yield, maximum, brittle fracture and arrest loads versus temperature ) is the most fundamental feature of the test. It is directly correlated to the appearance (percentage shear) of the fracture surface and also constitutes a straightforward experimental expression of the Davidenkov diagram, by which ductile-brittle transition temperature shifts are linked to irradiation damage mechanisms. In combination with static uniaxial tensile tests, it allows quantification of strain rate effects on the yielding and work hardening capacity of the steel. By contrast, the bulk of the absorbed energy and lateral expansion stems from ductile stable crack growth associated with plastic deformation under conditions, unrepresentative of the constraints and stress-strain field near the tip of a sharp crack in a pressure vessel. It is shown that the temperature at which fixed energy is absorbed in the test (41 or 68 Joules) cannot always trace to acceptable accuracy the effect of steel service exposure on the ductile - brittle transition temperature and on cleavage fracture toughness. It is contented that this can be done more reliably by using characteristic temperatures of the load diagram. An attempt to determine the engineering and regulatory implications of this physically-grounded fracture toughness approach is made.

  9. On the use of the instrumented Charpy-V impact signal for assessment of RPVS embrittlement

    International Nuclear Information System (INIS)

    Fabry, A.; Van Walle, E.; Van de Velde, J.; Chauoadi, R.; Puzzolante, J.L.; Van Ransbeeck, Th.; Verstrepen, A.

    1995-12-01

    In the context of LWR pressure vessel surveillance, the significance of the Cv notch impact test instrumented by strain gages has been revised. The load diagram (general yield, maximum, brittle fracture and arrest loads versus temperature ) is the most fundamental feature of the test. It is directly correlated to the appearance (percentage shear) of the fracture surface and also constitutes a straightforward experimental expression of the Davidenkov diagram, by which ductile-brittle transition temperature shifts are linked to irradiation damage mechanisms. In combination with static uniaxial tensile tests, it allows quantification of strain rate effects on the yielding and work hardening capacity of the steel. By contrast, the bulk of the absorbed energy and lateral expansion stems from ductile stable crack growth associated with plastic deformation under conditions, unrepresentative of the constraints and stress-strain field near the tip of a sharp crack in a pressure vessel. It is shown that the temperature at which fixed energy is absorbed in the test (41 or 68 Joules) cannot always trace to acceptable accuracy the effect of steel service exposure on the ductile - brittle transition temperature and on cleavage fracture toughness. It is contented that this can be done more reliably by using characteristic temperatures of the load diagram. An attempt to determine the engineering and regulatory implications of this physically-grounded fracture toughness approach is made

  10. Phase transformation and impact properties in the experimentally simulated weld heat-affected zone of a reduced activation ferritic/martensitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Joonoh, E-mail: mjo99@kims.re.kr [Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Lee, Chang-Hoon; Lee, Tae-Ho [Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Jang, Min-Ho [Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Division of Materials Science and Engineering, Hanyang University, Seongdong-ku, Seoul 133-791 (Korea, Republic of); Park, Min-Gu [Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Department of Material Science and Engineering, Pusan National University, 30 Jangjeon-Dong, Geumjeong-gu, Pusan 609-735 (Korea, Republic of); Han, Heung Nam [Department of Materials Science and Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742 (Korea, Republic of)

    2014-12-15

    In this work, the phase transformation and impact properties in the weld heat-affected zone (HAZ) of a reduced activation ferritic/martensitic (RAFM) steel are investigated. The HAZs were experimentally simulated using a Gleeble simulator. The base steel consisted of tempered martensite through normalizing at 1000 °C and tempering at 750 °C, while the HAZs consisted of martensite, δ-ferrite and a small volume of autotempered martensite. The impact properties using a Charpy V-notch impact test revealed that the HAZs showed poor impact properties due to the formation of martensite and δ-ferrite as compared with the base steel. In addition, the impact properties of the HAZs further deteriorated with an increase in the δ-ferrite fraction caused by increasing the peak temperature. The impact properties of the HAZs could be improved through the formation of tempered martensite after post weld heat treatment (PWHT), but they remained lower than that of the base steel because the δ-ferrite remained in the tempered HAZs.

  11. Synchrotron analysis of toughness anomalies in nanostructured bainite

    International Nuclear Information System (INIS)

    Fielding, L.C.D.; Jones, N.G.; Walsh, J.; Van Boxel, S.; Blackmur, M.S.; Lee, P.D.; Withers, P.J.; Stone, H.J.; Bhadeshia, H.K.D.H.

    2016-01-01

    High-resolution synchrotron X-ray diffraction has been used to characterise the notch root regions of Charpy impact test specimens of a superbainitic steel, both before and after loading. The changes in the volume fraction of austenite induced by the application of a three-point-bending load were quantified. Analysis of diffraction peak shifts revealed the extent of residual tensile and compressive strains present due to both machining and an applied load. The results lend support to the hypothesis that the comparatively low energies absorbed during Charpy impact testing of superbainitic steels, <7 J, are due to the formation of stress-induced martensite at the notch root, prior to crack initiation.

  12. Specimen size effects in Charpy impact testing

    International Nuclear Information System (INIS)

    Alexander, D.J.; Klueh, R.L.

    1989-01-01

    Full-size , half-size, and third-size specimens from several different steels have been tested as part of an ongoing alloy development program. The smaller specimens permit more specimens to be made from small trail heats and are much more efficient for irradiation experiments. The results of several comparisons between the different specimen sizes have shown that the smaller specimens show qualitatively similar behavior to large specimens, although the upper-shelf energy level and ductile-to-ductile transition temperature are reduced. The upper-shelf energy levels from different specimen sizes can be compared by using a simple volume normalization method. The effect of specimen size and geometry on the ductile-to-ductile transition temperature is more difficult to predict, although the available data suggest a simple shift in the transition temperature due to specimen size changes.The relatively shallower notch used in smaller specimens alters the deformation pattern, and permits yielding to spread back to the notched surface as well as through to the back. This reduces the constraint and the peak stresses, and thus the initiation of cleavage is more difficult. A better understanding of the stress and strain distributions is needed. 19 refs., 3 figs., 3 tabs

  13. Postirradiation notch ductility tests of ESR alloy HT-9 and modified 9Cr-1Mo alloy from UBR reactor experiments

    International Nuclear Information System (INIS)

    Hawthorne, J.R.

    1984-01-01

    During this period, irradiation exposures at 300 0 C and 150 0 C to approx. 8 x 10 19 n/cm 2 , E > 0.1 MeV, were completed for the Alloy HT-9 plate and the modified Alloy 9Cr-1Mo plates, respectively. Postirradiation tests of Charpy-V (C/sub v/) specimens were completed for both alloys; other specimen types included in the reactor assemblies were fatigue precracked Charpy-V (PCC/sub v/), half-size Charpy-V, and in the case of the modified 9Cr-1Mo, 2.54 mm thick compact tension specimens

  14. Fractography evaluation of impact and tensile specimens from the HFBR [High Flux Beam Reactor

    International Nuclear Information System (INIS)

    Czajkowski, C.J.

    1989-10-01

    The Materials Technology Group of the Department of Nuclear Energy (DNE) at Brookhaven National Laboratory (BNL) has performed a fractographic examination of neutron irradiated and unirradiated tensile and Charpy ''V'' notch specimens. The evaluation was carried out using a scanning electron microscope (SEM) to evaluate the fracture mode. Photomicrographs were then evaluated to determine the extent of ductility present on the fracture surfaces of the unirradiated specimens. Ductility area measurements ranged from 4.6--9.5% on typical photomicrographs examined. 12 figs

  15. V-notch tip subjected to in-plane mixed mode loading: overview of recent results and possible future outcomes

    Directory of Open Access Journals (Sweden)

    F. Berto

    2017-07-01

    Full Text Available . The fictitious notch rounding concept is applied for the first time to V-notches with root hole subjected to in-plane mixed mode loading. Outof-bisector crack propagation is taken into account. The fictitious notch radius is determined as a function of the real notch radius, the microstructural support length and the notch opening angle. Due to the complexity of the problem, a method based on the simple normal stress failure criterion has been used. It is combined with the maximum tangential stress criterion to determine the crack propagation angle. An analytical method based on Neuber's procedure has been developed. The method provides the values of the microstructural support factor as a function of the mode ratio and the notch opening angle. The support factor is considered to be independent of the microstructural support length. Finally, for comparison, the support factor is determined on a purely numerical basis by iterative analysis of FE models.

  16. Material properties characterization of low carbon steel using TBW and PWHT techniques in smooth-contoured and U-shaped geometries

    International Nuclear Information System (INIS)

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

    2013-01-01

    This paper investigates the effects of the temper bead welding (TBW) technique and post weld heat treatment (PWHT) on mechanical properties of multi-layer welding on low carbon steel specimens using Charpy V-notch impact testing and tensile testing. Several samples of two different weld geometries, viz. (i) smooth-contoured, and (ii) U-shaped were made with multiple bead layers using both TBW and PWHT techniques. Impact testing showed that at room temperature and below, TBW gave an impact toughness in the Heat Affected Zone (HAZ) better than both PWHT and the parent material. At temperatures higher than the room temperature but below 60 °C, PWHT gave better impact toughness in the HAZ. Above 60 °C, both TBW and PWHT showed impact toughness lower than that of the parent material. In tensile testing, both TBW and PWHT weld metal specimens produced acceptable results; however, TBW gave yield and tensile strengths closer to that of the actual material than PWHT. -- Highlights: • Effects of post weld heat treatment (PWHT) and temper bead welding (TBW) on properties are tested. • Charpy V-notch impact and tensile testing was performed on multi-layer welding of low carbon steel. • At room temperature and below, TBW gave better impact toughness than both PWHT and parent material. • Above room temperature but below 60 °C, PWHT gave better impact toughness than TBW. • Above 60 °C, both TBW and PWHT showed impact toughness lower than that of parent material

  17. Assessment of the effects of neutron fluence on Swedish nuclear pressure vessels

    International Nuclear Information System (INIS)

    Rao, S.

    1980-11-01

    Nuclear pressure vessels are subject to neutron irradiation during service causing embrittlement. This is one important factor in the overall problem of reactor vessel integrity. At present the irradiation effects are mainly assessed by the Charpy V-notch test. Two measures of embrittlement are defined: the increase of the ductile/brittle transition temperature and the decrease in the upper-shelf energy. The object of the present work is to assess these changes for the Swedish nuclear pressure vessels. On the basis of data from irradiations carried out in other countries and Swedish surveillance programmes, the expected end of life embrittlement is estimated for Swedish vessels. The results show that the embrittlement of most reactor vessels is expected to be quite small. Oskarshamn 1 and PWR-vessels, however, will probably show moderate changes, the former due to the higher copper content, and the latter due to the high end of life fluences. Some of the vessel materials which exhibit marginal properties in the upper-shelf energy, as measured by the Charpy V-notch impact test, are identified. It is recommended that fracture mechanics analyses be applied in these cases. (author)

  18. Effects of Notch Misalignment and Tip Radius on Displacement Field in V-Notch Rail Shear Test as Determined by Photogrammetry

    Science.gov (United States)

    Hill, Charles S.; Oliveras, Ovidio M.

    2011-01-01

    Evolution of the 3D strain field during ASTM-D-7078 v-notch rail shear tests on 8-ply quasi-isotropic carbon fiber/epoxy laminates was determined by optical photogrammetry using an ARAMIS system. Specimens having non-optimal geometry and minor discrepancies in dimensional tolerances were shown to display non-symmetry and/or stress concentration in the vicinity of the notch relative to a specimen meeting the requirements of the standard, but resulting shear strength and modulus values remained within acceptable bounds of standard deviation. Based on these results, and reported difficulty machining specimens to the required tolerances using available methods, it is suggested that a parametric study combining analytical methods and experiment may provide rationale to increase the tolerances on some specimen dimensions, reducing machining costs, increasing the proportion of acceptable results, and enabling a wider adoption of the test method.

  19. Postirradiation fracture toughness tests of ESR alloy HT-9 and modified 9Cr-1Mo alloy from UBR reactor experiments

    International Nuclear Information System (INIS)

    Hawthorne, J.R.; Reed, J.R.; Sprague, J.A.

    1984-01-01

    Alloy HT-9 and Modified 9Cr-1Mo are being evaluated for potential applications as first wall materials in magnetic fusion reactors. Objectives of the current research task were to test fatigue-precracked Charpy-V (PCC/sub v/) specimens from representative plates irradiated in the UBR reactor at 149 0 C or 300 0 C, and, to compare the results against postirradiation notch ductility data developed previously for the materials. Both plates represent electroslag refined (ESR) melt processing. PCC/sub v/ specimens of Alloy HT-9 and Modified 9Cr-1Mo alloy were irradiated at 300 0 C and 149 0 C, respectively, to approx.0.8 X 10 20 n/cm 2 , E > 0.1 MeV. During this period, postirradiation tests for fracture toughness were completed and results compared to notch ductility determinations from standard Charpy-V (C/sub v/) specimens irradiated in the same reactor experiments. Fracture surface examinations by SEM are also reported

  20. On the Use of the Instrumented Charpy-V Impact Signal for Assessment of RPVS Embrittlement

    Energy Technology Data Exchange (ETDEWEB)

    Fabry, A; van Walle, E; Van de Velde, J; Chaouadi, R; Puzzolante, J L; Van Ransbeeck, Th; Verstrepen, A

    1994-04-01

    In the context of LWR pressure vessel surveillance, the significance of the Cv notch impact test, instrumented by strain gages, has been revisited. The load diagram - general yield, maximum, brittle fracture and arrest loads versus temperature - is the most fundamental feature of the test. It is directly correlated to the appearance (percentage shear) of the fracture surface, and also constitutes a straightforward expression of the davidenkov diagram, by which DBTT shifts are linked to damage mechanisms. In combination with static uniaxial tensile tests, it allows to quantify strain rate effects on the yielding and work hardening capability of the steel. By contrast, the bulk of the absorbed energy and lateral expansion stems from plastic deformation, associated to ductile stable crack growth under conditions unrepresentative of the constraints and stress-strain field near the tip of a sharp crack in a pressure vessel. It has been shown that the temperature at which a fixed energy is absorbed in the test (41 or 68 J) cannot always trace, to acceptable accuracy, the effect of steel service exposure on the ductile-brittle transition temperature DBTT and on cleavage fracture toughness. It is contented that this can be done more reliably by using characteristic temperatures of the load diagram. The engineering and regulatory implications of this physically- grounded dynamic fracture toughness indexation approach are reported. Some related findings relative to damage mechanisms and strain ageing effects are outlined.

  1. On the Use of the Instrumented Charpy-V Impact Signal for Assessment of RPVS Embrittlement

    International Nuclear Information System (INIS)

    Fabry, A.; van Walle, E.; Van de Velde, J.; Chaouadi, R.; Puzzolante, J.L.; Van Ransbeeck, Th.; Verstrepen, A.

    1994-04-01

    In the context of LWR pressure vessel surveillance, the significance of the Cv notch impact test, instrumented by strain gages, has been revisited. The load diagram - general yield, maximum, brittle fracture and arrest loads versus temperature - is the most fundamental feature of the test. It is directly correlated to the appearance (percentage shear) of the fracture surface, and also constitutes a straightforward expression of the davidenkov diagram, by which DBTT shifts are linked to damage mechanisms. In combination with static uniaxial tensile tests, it allows to quantify strain rate effects on the yielding and work hardening capability of the steel. By contrast, the bulk of the absorbed energy and lateral expansion stems from plastic deformation, associated to ductile stable crack growth under conditions unrepresentative of the constraints and stress-strain field near the tip of a sharp crack in a pressure vessel. It has been shown that the temperature at which a fixed energy is absorbed in the test (41 or 68 J) cannot always trace, to acceptable accuracy, the effect of steel service exposure on the ductile-brittle transition temperature DBTT and on cleavage fracture toughness. It is contented that this can be done more reliably by using characteristic temperatures of the load diagram. The engineering and regulatory implications of this physically- grounded dynamic fracture toughness indexation approach are reported. Some related findings relative to damage mechanisms and strain ageing effects are outlined

  2. Change of Charpy impact fracture behavior of precracked ferritic specimens due to thermal aging in sodium

    International Nuclear Information System (INIS)

    Hu, W.L.

    1985-12-01

    A series of tests were conducted to evaluate the effect of sodium on the impact fracture behavior of precracked Charpy specimens made of HT-9 weldment. One set of samples was precracked prior to sodium aging and the other set was precracked after aging in sodium. Both set of specimens exhibited the same DBTT. Samples precracked prior to sodium exposure, however, showed a 40% reduction in the upper shelf energy (USE) as compared to the set precracked after aging. The results suggest that the fracture toughness of the material may be reduced if an existing crack was soaked in sodium at elevated temperature for a period of time

  3. Notch2 Signaling Maintains NSC Quiescence in the Murine Ventricular-Subventricular Zone

    Directory of Open Access Journals (Sweden)

    Anna Engler

    2018-01-01

    Full Text Available Neurogenesis continues in the ventricular-subventricular zone (V-SVZ of the adult forebrain from quiescent neural stem cells (NSCs. V-SVZ NSCs are a reservoir for new olfactory bulb (OB neurons that migrate through the rostral migratory stream (RMS. To generate neurons, V-SVZ NSCs need to activate and enter the cell cycle. The mechanisms underlying NSC transition from quiescence to activity are poorly understood. We show that Notch2, but not Notch1, signaling conveys quiescence to V-SVZ NSCs by repressing cell-cycle-related genes and neurogenesis. Loss of Notch2 activates quiescent NSCs, which proliferate and generate new neurons of the OB lineage. Notch2 deficiency results in accelerated V-SVZ NSC exhaustion and an aging-like phenotype. Simultaneous loss of Notch1 and Notch2 resembled the total loss of Rbpj-mediated canonical Notch signaling; thus, Notch2 functions are not compensated in NSCs, and Notch2 is indispensable for the maintenance of NSC quiescence in the adult V-SVZ.

  4. Effect of tempering temperature on the microstructure and mechanical properties of a reactor pressure vessel steel

    Energy Technology Data Exchange (ETDEWEB)

    Li, C.W.; Han, L.Z.; Luo, X.M.; Liu, Q.D.; Gu, J.F., E-mail: gujf@sjtu.edu.cn

    2016-08-15

    The microstructure and mechanical properties of reactor pressure vessel (RPV) steel were investigated after tempering at different temperatures ranging from 580 to 700 °C for 5 h. With increasing tempering temperature, the impact toughness, which is qualified by Charpy V-notch total absorbed energy, initially increases from 142 to 252 J, and then decreases to 47 J, with a maximum value at 650 °C, while the ultimate tensile strength varies in exactly the opposite direction. Comparing the microstructure and fracture surfaces of different specimens, the variations in toughness and strength with the tempering temperature were generally attributed to the softening of the bainitic ferrite, the agminated Fe{sub 3}C carbides that resulted from decomposition of martensite/austenite (M/A) constituents, the precipitation of Mo{sub 2}C carbides, and the newly formed M/A constituents at the grain boundaries. Finally, the correlation between the impact toughness and the volume fraction of the M/A constituents was established, and the fracture mechanisms for the different tempering conditions are explained. - Highlights: • The dependence of the deterioration of impact toughness on tempering temperature has been analysed. • The instrumented Charpy V-notch impact test has been employed to study the fracture mechanism. • The influence of M/A constituents on different fracture mechanisms based on the hinge model has been demonstrated. • A correlation between the mechanical properties and the amount of M/A constituents has been established.

  5. Irradiation effects in strain aged pressure vessel steel

    Energy Technology Data Exchange (ETDEWEB)

    Grounes, M; Myers, H P

    1962-02-15

    Tensile specimens, Charpy-V notch and subsize impact specimens of an aluminium killed carbon manganese steel, have been irradiated at 160 - 190 deg C in the reactor G1. The total neutron dose received was 2.4 x 10{sup 18} n/cm{sup 2} (> 1 MeV). Specimens were prepared from normalized plate and from strain aged material from the same plate. It was found that the changes in brittle ductile transition temperature due to neutron irradiation and those due to strain ageing must be considered additive.

  6. Investigation of the effects on Charpy impact characteristics by shape of pendulum striking edge

    International Nuclear Information System (INIS)

    Kawai, Toshihiko; Etoh, Mikio; Hanawa, Namio; Shibaike, Masayuki; Inoue, Kazuo.

    1983-01-01

    Charpy impact test is used versatilely and practically as the method of evaluating the toughness of metals. In Japan, usually the JIS type testing machines are used, but recently, the test with ASTM type testing machines has been often demanded for steel materials for export or for nuclear use. Accordingly, the testing machines of both types must be installed, the testing works become troublesome, and the costs of initial investment, maintenance, management and so on increase. When the standards in various countries were investigated, the stipulation on the various particulars of the testing machines was almost similar except the shape of striking edges, which are 8mm radius in ASTM and 2mm radius in other standards. Recently it was clarified that there was some difference between the impact values of high toughness steel using JIS and ASTM machines. In order to clarify the cause of this difference and to unify the shape of edges, the investigation was carried out by the working group. The investigation of the effect of the difference of edge shapes on impact values, the analysis of fracture phenomena in impact test and the consideration on the results are reported. ASTM type testing machines should not be used for mild steel when absorbed energy exceeds 10kgf-m. (Kako, I.)

  7. A Metallurgical Evaluation of the Powder-Bed Laser Additive Manufactured 4140 Steel Material

    Science.gov (United States)

    Wang, Wesley; Kelly, Shawn

    2016-03-01

    Using laser powder bed fusion (PBF-L) additive manufacturing (AM) process for steel or iron powder has been attempted for decades. This work used a medium carbon steel (AISI 4140) powder to explore the feasibility of AM. The high carbon equivalent of 4140 steel (CEIIW ≈ 0.83) has a strong tendency toward cold cracking. As such, the process parameters must be carefully controlled to ensure the AM build quality. Through an orthogonally designed experimental matrix, a laser-welding procedure was successfully developed to produce 4140 steel AM builds with no welding defects. In addition, the microstructure and micro-cleanliness of the as-welded PBF-L AM builds were also examined. The results showed an ultra-fine martensite lath structure and an ultra-clean internal quality with minimal oxide inclusion distribution. After optimizing the PBF-L AM process parameters, including the laser power and scan speed, the as-welded AM builds yielded an average tensile strength higher than 1482 MPa and an average 33 J Charpy V-notch impact toughness at -18°C. The surface quality, tensile strength, and Charpy V-notch impact toughness of AM builds were comparable to the wrought 4140 steel. The excellent mechanical properties of 4140 steel builds created by the PBF-L AM AM process make industrial production more feasible, which shows great potential for application in the aerospace, automobile, and machinery industries.

  8. A Study on the Low Temperature Brittleness by Cyclic Cooling-Heating of Low Carbon Hot Rolled Steel Plate

    International Nuclear Information System (INIS)

    Lee, Hyo Bok

    1979-01-01

    The ductile-brittle transition phenomenon of low carbon steel has been investigated using the standard Charpy V-notch specimen. Dry ice and acetone were used as refrigerants. Notched specimens were cut from the hot rolled plate produced at POSCO for the Olsen impact test. The effect of cyclic cooling and heating of 0.14% carbon steel on the embrittlement was extensively examined. The ductile-brittle transition temperature was found to be approximately-30 .deg. C. The transition temperature was gradually increased as the number of cooling-heating cycles increased. On a typical V-notch fracture surface it was found that the ductile fracture surface showed a thick and fibrous structure, while the brittle fracture surface a small and light grain with irregular disposition. As expected, the transition temperature was also increased as the carbon content of steel increased. Compared with the case of 0.14% carbon steel, the transition temperature of 0.17% carbon steel was found to be increased about 12 .deg. C

  9. Metallographic study of reconstitution welding in inserts of 1 cm3

    International Nuclear Information System (INIS)

    Romero C, J.; Garcia R, R.; Fernandez T, F.; Perez R, N.; Rocamontes A, M.

    2007-01-01

    In this article, the welding metallographic study carried out in Charpy test tubes reconstituted with notch in 'V', used in the surveillance programs of the vessel in nucleo electric plants is described. Inserts of 1 cm 3 are used, where the inserts are usually rectangular of minimum 18 millimeters of length. The importance of using inserts of 1 cm 3 is that the mechanical properties can be measured in another direction of the vessel steel, when changing the direction or sense of the notch in 'V' or the face where this notch is made in the insert. (Author)

  10. Influence of Striking Edge Radius (2 mm versus 8 mm) on Instrumented Charpy Data and Absorbed Energies

    Energy Technology Data Exchange (ETDEWEB)

    Lucon, E.

    2008-08-15

    The most commonly used test standards for performing Charpy impact tests (ISO 148 and ASTM E 23) envisage the use of strikers having different radii of the striking edge, i.e. 2 mm (ISO) and 8 mm (ASTM). The effect of striker geometry on Charpy results was extensively studied in the past in terms of absorbed energy measured by the machine encoder, but few investigations are available on the influence of striker configuration on the results of instrumented Charpy tests (characteristic forces, displacements and integrated energy). In this paper, these effects are investigated based on the analysis of published results from three interlaboratory studies and some unpublished Charpy data obtained at SCK-CEN. The instrumented variables which are the most sensitive to the radius of the striking edge are the maximum force and its corresponding displacement, with 8mm-strikers providing systematically higher values. Absorbed energies, obtained both from the instrumented trace and from the pendulum encoder, are almost insensitive to the type of striker up to 200 J. For higher energy levels, the values obtained from 8mm strikers become progressively larger. Data scatter is generally higher for 2mm-strikers.

  11. Progress Report on Alloy 617 Notched Specimen Testing

    Energy Technology Data Exchange (ETDEWEB)

    McMurtrey, Michael David [Idaho National Lab. (INL), Idaho Falls, ID (United States); Wright, Richard Neil [Idaho National Lab. (INL), Idaho Falls, ID (United States); Lillo, Thomas Martin [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-08-01

    Creep behavior of Alloy 617 has been extensively characterized to support the development of a draft Code Case to qualify Alloy 617 in Section III division 5 of the ASME Boiler and Pressure Vessel Code. This will allow use of Alloy 617 in construction of nuclear reactor components at elevated temperatures and longer periods of time (up to 950°C and 100,000 hours). Prior to actual use, additional concerns not considered in the ASME code need to be addressed. Code Cases are based largely on uniaxial testing of smooth gage specimens. In service conditions, components will generally be under multi axial loading. There is also the concern of the behavior at discontinuities, such as threaded components. To address the concerns of multi axial creep behavior and at geometric discontinuities, notched specimens have been designed to create conditions representative of the states that service components experience. Two general notch geometries have been used for these series of tests: U notch and V notch specimens. The notches produce a tri axial stress state, though not uniform across the specimen. Characterization of the creep behavior of the U notch specimens and the creep rupture behavior of the V notch specimens provides a good approximation of the behavior expected of actual components. Preliminary testing and analysis have been completed and are reported in this document. This includes results from V notch specimens tested at 900°C and 800°C. Failure occurred in the smooth gage section of the specimen rather than at the root of the notch, though some damage was present at the root of the notch, where initial stress was highest. This indicates notch strengthening behavior in this material at these temperatures.

  12. Effect of mechanical alloying atmosphere on the microstructure and Charpy impact properties of an ODS ferritic steel

    International Nuclear Information System (INIS)

    Oksiuta, Z.; Baluc, N.

    2009-01-01

    Two types of oxide dispersion strengthened (ODS) ferritic steels, with the composition of Fe-14Cr-2W-0.3Ti-0.3Y 2 O 3 (in weight percent), have been produced by mechanically alloying elemental powders of Fe, Cr, W, and Ti with Y 2 O 3 particles either in argon atmosphere or in hydrogen atmosphere, degassing at various temperatures, and compacting the mechanically alloyed powders by hot isostatic pressing. It was found in particular that mechanical alloying in hydrogen yields a significant reduction in oxygen content in the materials, a lower dislocation density, and a strong improvement in the fast fracture properties of the ODS ferritic steels, as measured by Charpy impact tests.

  13. Microstructure, Composition, and Impact Toughness Across the Fusion Line of High-Strength Bainitic Steel Weldments

    Science.gov (United States)

    Lan, Liangyun; Kong, Xiangwei; Chang, Zhiyuan; Qiu, Chunlin; Zhao, Dewen

    2017-09-01

    This paper analyzed the evolution of microstructure, composition, and impact toughness across the fusion line of high-strength bainitic steel weldments with different heat inputs. The main purpose was to develop a convenient method to evaluate the HAZ toughness quickly. The compositions of HAZ were insensitive to higher contents of alloy elements ( e.g., Ni, Mo) in the weld metal because their diffusion distance is very short into the HAZ. The weld metal contained predominantly acicular ferrite at any a heat input, whereas the main microstructures in the HAZ changed from lath martensite/bainite to upper bainite with the increasing heat input. The evolution of HAZ toughness in relation to microstructural changes can be revealed clearly combined with the impact load curve and fracture morphology, although the results of impact tests do not show an obvious change with heat input because the position of Charpy V notch contains the weld metal, HAZ as well as a part of base metal. As a result, based on the bead-on-plate welding tests, the welding parameter affecting the HAZ toughness can be evaluated rapidly.

  14. Fracture toughness of Charpy-size compound specimens and its application in engineering

    International Nuclear Information System (INIS)

    Zhang, X.P.; Shi, Y.W.

    1994-01-01

    The use of a pre-cracked Charpy-size specimen with a side-groove to evaluate the fracture toughness of materials has been researched and considered. This method not only satisfies the demand for small-size specimens in surveillance tests of fracture toughness but also avoids using complicated physical methods to monitor the initial conditions of crack propagation. For most materials this method has solved the problem in which the small-size specimen did not satisfy the valid conditions of a fracture toughness measurement. In order to obtain more information from neutron-irradiated sample specimens and raise the reliability of fracture toughness surveillance tests, it has been considered more important to repeatedly exploit the broken Charpy-size specimen tested in the surveillance test, and to make it renewable. In this work, on the renewing design and utilization of Charpy-size specimens, nine data on fracture toughness can be obtained from one pre-cracked side-grooved Charpy-size specimen, while at present usually only one to three data on fracture toughness can be obtained from one Charpy-size specimen. Thus, it is found that the new method would improve the reliability of fracture toughness surveillance testing and evaluation. In addition, some factors that affect the optimum design of pre-cracked deep side-groove Charpy-size compound specimens have also been discussed. (author)

  15. Structural integrity of water reactor pressure boundary components. Progress report ending 29 February 1976

    International Nuclear Information System (INIS)

    Loss, F.J.

    1976-01-01

    The report describes progress in the following areas: (a) fatigue crack propagation in reactor pressure vessel steels in an air environment, (b) dynamic fracture toughness of 1-in. (25-mm) and precracked Charpy-V bend specimens under impact loading, (c) postirradiation notch ductility and properties recovery in reactor vessel steels, (d) factors contributing to variable resistance of structural steels to radiation embrittlement, and (e) the initial program plan to investigate the phenomena of warm prestress and plastic net ligament in support of thermal shock studies

  16. Analysis of the irradiation data for A302B and A533B correlation monitor materials

    International Nuclear Information System (INIS)

    Wang, J.A.

    1996-04-01

    The results of Charpy V-notch impact tests for A302B and A533B-1 Correlation Monitor Materials (CMM) listed in the surveillance power reactor data base (PR-EDB) and material test reactor data base (TR-EDB) are analyzed. The shift of the transition temperature at 30 ft-lb (T 30 ) is considered as the primary measure of radiation embrittlement in this report. The hyperbolic tangent fitting model and uncertainty of the fitting parameters for Charpy impact tests are presented in this report. For the surveillance CMM data, the transition temperature shifts at 30 ft-lb (ΔT 30 ) generally follow the predictions provided by Revision 2 of Regulatory Guide 1.99 (R.G. 1.99). Difference in capsule temperatures is a likely explanation for large deviations from R.G. 1.99 predictions. Deviations from the R.G. 1.99 predictions are correlated to similar deviations for the accompanying materials in the same capsules, but large random fluctuations prevent precise quantitative determination. Significant scatter is noted in the surveillance data, some of which may be attributed to variations from one specimen set to another, or inherent in Charpy V-notch testing. The major contributions to the uncertainty of the R.G. 1.99 prediction model, and the overall data scatter are from mechanical test results, chemical analysis, irradiation environments, fluence evaluation, and inhomogeneous material properties. Thus in order to improve the prediction model, control of the above-mentioned error sources needs to be improved. In general the embrittlement behavior of both the A302B and A533B-1 plate materials is similar. There is evidence for a fluence-rate effect in the CMM data irradiated in test reactors; thus its implication on power reactor surveillance programs deserves special attention

  17. Miniature Precracked Charpy Specimens for Measuring the Master Curve Reference Temperature of RPV Steels at Impact Loading Rates

    Energy Technology Data Exchange (ETDEWEB)

    Lucon, E.; Scibetta, M.; Puzzolante, L.

    2008-10-15

    In the framework of the 2006 Convention, we investigated the applicability of fatigue precracked miniature Charpy specimens of KLST type (MPCC - B = 3 mm, W = 4 mm and L = 27 mm) for impact toughness measurements, using the well-characterized JRQ RPV steel. In the ductile to-brittle transition region, MPCC tests analyzed using the Master Curve approach and compared to data previously obtained from PCC specimens had shown a more ductile behavior and therefore un conservative results. In the investigation presented in this report, two additional RPV steels have been used to compare the performance of impact-tested MPCC and PCC specimens in the transition regime: the low-toughness JSPS steel and the high-toughness 20MnMoNi55 steel. The results obtained (excellent agreement for 20MnMoNi55 and considerable differences between T0 values for JSPS) are contradictory and do not presently allow qualifying the MPCC specimens as a reliable alternative to PCC samples for impact toughness measurements.

  18. Metallographic study of reconstitution welding in inserts of 1 cm{sup 3}; Estudio metalografico de soldaduras de reconstitucion en insertos de 1 cm{sup 3}

    Energy Technology Data Exchange (ETDEWEB)

    Romero C, J.; Garcia R, R.; Fernandez T, F.; Perez R, N.; Rocamontes A, M. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico)

    2007-07-01

    In this article, the welding metallographic study carried out in Charpy test tubes reconstituted with notch in 'V', used in the surveillance programs of the vessel in nucleo electric plants is described. Inserts of 1 cm{sup 3} are used, where the inserts are usually rectangular of minimum 18 millimeters of length. The importance of using inserts of 1 cm{sup 3} is that the mechanical properties can be measured in another direction of the vessel steel, when changing the direction or sense of the notch in 'V' or the face where this notch is made in the insert. (Author)

  19. Characterization by notched and precracked Charpy tests of the in-service degradation of RPV steel fracture toughness

    International Nuclear Information System (INIS)

    Fabry, A.

    1997-01-01

    The current engineering and regulatory practice to estimate fracture toughness safety margins for nuclear reactor pressure vessels (RPVs) relies heavily on the CVN impact test. Techniques to estimate in-service toughness degradation directly using a variety of precracked specimens are under development worldwide. Emphasis is on their miniaturization. In the nuclear context, it is essential to address many issues such as representativity of the surveillance programs with respect to the vessel in terms of materials and environment, transferability of test results to the structure (constraint and size effects), lower bound toughness certification, creadibility relative to trends of exising databases. An enhanced RPV surveillance strategy in under development in Belgium. It combines state-of-the-art micromechanical and damage modelling to the evaluation of CVN load-deflection signals, tensile stress-strain curves and slow-bend tests of reconstituted precracked Charpy specimens. A probabilistic micromechanical model has been established for static and dynamic transgranular cleavage initiation fracture toughness in the ductile-brittle transition temperature range. This model allows to project toughness bounds for any steel embrittlement condition from the corresponding CVN and static tensile properties, using a single scaling factor defined by imposing agreement with toughness tests in a single condition. The outstanding finding incorporated by this toughness transfer model is that the microcleavage fracture stress is affected by temperature in the ductile-brittle transition and that this influence is strongly correlated to the flow stress: this explains the shape of the K Ic n K Id temperature curves as well as the actual magnitude of the strain rate and irradiation effects. Furthermore, CVN crack arrest loads and fracture appearance are also taken advantage of in order to estimate K Ia degradation. Finally, the CVN-tensile load-temperature diagram provides substantial

  20. A mechanical property and stress corrosion evaluation of VIM-ESR-VAR work strengthened and direct double aged Inconel 718 bar material

    Science.gov (United States)

    Montano, J. W.

    1986-01-01

    Presented are the mechanical properties and the stress corrosion resistance of triple melted vacuum induction melted (VIM), electro-slag remelted (ESR), and vacuum arc remelted (VAR), solution treated, work strengthened and direct double aged Inconel 718 alloy bars 4.00 in. (10.16) and 5.75 in. (14.60 cm) diameter. Tensile, charpy v-notched impact, and compact tension specimens were tested at ambient temperature in both the longitudinal and transverse directions. Longitudinal tensile and yield strengths in excess of 220 ksi (1516.85 MPa) and 200 ksi (1378.00 MPa) respectively, were realized at ambient temperature. Additional charpy impact and compact tension tests were performed at -100 F (-73 C). Longitudinal charpy impact strength equalled or exceeded 12.0 ft-lbs (16.3 Joules) at ambient and at -100 F(-73 C) while longitudinal compact (LC) tension fracture toughness strength remained above 79 ksi (86.80 MPa) at ambient and at -100 F(-73 C) temperatures. No failures occurred in the longitudinal or transverse tensile specimens stressed to 75 and 100 percent of their respective yield strengths and exposed to a salt fog environment for 180 days. Tensile tests performed after the stress corrosion test indicated no mechanical property degradation.

  1. Effect of weld metal toughness on fracture behavior under ultra-low cycle fatigue loading (earthquake)

    Energy Technology Data Exchange (ETDEWEB)

    Kermajani, M. [School of Materials Engineering, College of Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Ghaini, F. Malek, E-mail: Fmalek@modares.ac.ir [School of Materials Engineering, College of Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Miresmaeili, R. [School of Materials Engineering, College of Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Aghakouchak, A.A. [School of Civil Engineering, College of Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Shadmand, M. [Department of Research and Development, MAPNA Electric and Control (MECO) Company, Karaj (Iran, Islamic Republic of)

    2016-06-21

    Results from 12 ultra-low cycle fatigue tests performed on the weld metals of both toughness and non-toughness rated grades are presented. Fracture resistance under these loadings seemed to be dependent on materials' toughness, displacement amplitude, and stress state triaxiality, while the toughness effect was more highlighted at high stress levels and concentrations. To study the effect of microstructures on these failures, supporting ancillary tests including all-weld tension coupons, Charpy V-notched impact tests, and optical and scanning electron microscope analyses were performed. The favored microstructures appeared to be those which absorbed energy by plastic deformation and, hence, hindered void formation and/or could avoid crack propagation by deflection. Considering the response of the tested materials to cyclic loadings and the requirements of the materials specified in AISC341 Provisions could question the adequacy of these requirements for weld metals. However, the role of microstructural features like inclusions would be the same in both the Charpy impact tests and ultra-low cycle loadings.

  2. Crack initiation life in notched Ti-6Al-4V titanium bars under uniaxial and multiaxial fatigue: synthesis based on the averaged strain energy density approach

    Directory of Open Access Journals (Sweden)

    Giovanni Meneghetti

    2017-07-01

    Full Text Available The fatigue behaviour of circumferentially notched specimens made of titanium alloy, Ti-6Al-4V, has been analysed. To investigate the notch effect on the fatigue strength, pure bending, pure torsion and multiaxial bending-torsion fatigue tests have been carried out on specimens characterized by two different root radii, namely 0.1 and 4 mm. Crack nucleation and subsequent propagation have been accurately monitored by using the direct current potential drop (DCPD technique. Based on the results obtained from the potential drop technique, the crack initiation life has been defined in correspondence of a relative potential drop increase V/V0 equal to 1%, and it has been used as failure criterion. Doing so, the effect of extrinsic mechanisms operating during crack propagation phase, such as sliding contact, friction and meshing between fracture surfaces, is expected to be reduced. The experimental fatigue test results have been re-analysed by using the local strain energy density (SED averaged over a structural volume having radius R0 and surrounding the notch tip. Finally, the use of the local strain energy density parameter allowed us to properly correlate the crack initiation life of Ti-6Al-4V notched specimens, despite the different notch geometries and loading conditions involved in the tests

  3. Characterisation of weldment hardness, impact energy and microstructure in API X65 steel

    International Nuclear Information System (INIS)

    Hashemi, S.H.; Mohammadyani, D.

    2012-01-01

    The variation of microstructure and mechanical properties in various sub-zones of double submerged arc welded line pipe steel of grade API X65 was investigated. Instrumented Charpy V-notch tests and Vickers hardness experiments were conducted on the fusion zone, base metal and heat affected zone of the weld joint in 14.3 mm thick, 1219 mm outside diameter spiral pipeline. The lowest impact energy and the highest hardness level (160J and 218 HV, respectively) were recorded in the fusion zone. The low energy and high hardness characteristics of the seam weld can be attributed to its cast microstructure and the presence of grain boundary phases (such as proeutectoid ferrite), confirmed by standard metallographic observation. Despite this, service requirements set by the API 5L industry code (minimum impact energy of 73J, maximum hard spots of 350 HV) were fulfilled by the tested steel. Highlights: ► Experimental study of API X65 steel microstructure. ► Analysis of the relationship between X65 steel microstructure and hardness. ► Analysis of the relationship between X65 steel microstructure and impact energy. ► Presentation of detailed technical information on DSA welding in spiral pipes.

  4. Fractographic examination of HT-9 and 9Cr-1Mo Charpy specimens irradiated in the AD-2 test

    International Nuclear Information System (INIS)

    Gelles, D.S.; Hu, W.L.

    1983-01-01

    Fracture surface topologies have been examined using scanning electron microscopy for 20 selected half sized Charpy impact specimens of HT-9 and Modified 9Cr-1Mo in order to provide improved understanding of fracture toughness degradation as a result of irradiation for Path E alloys. The specimen matrix included unirradiated specimens and specimens irradiated in EBR-II in the AD-2 experiment. Also, hardness measurements have been made on selected irradiated Charpy specimens. The results of examinations indicate that irradiation hardening due to G-phase formation at 390 0 C is responsible for the large shift in ductile-to-brittle transition temperature (DBTT) found in HT-9. Toughness degradation in HT-9 observed following higher temperature irradiations is attributed to precipitation at delta ferrite stringers. Reductions in toughness as a consequence of irradiation in Modified 9Cr-1Mo are attributed to in-reactor precipitation of (V,Nb)C and M 23 C 6 . It is shown that crack propagation rates for ductile and brittle failure modes can be measured, that they differ by over an order of magnitude and that unexpected multiple shifts in fracture mode from ductile to brittle failure can be attributed to the effect of delta ferrite stringers on crack propagation rates

  5. Effect of effective grain size on Charpy impact properties of high-strength bainitic steels

    International Nuclear Information System (INIS)

    Shin, Sang Yong; Han, Seung Youb; Lee, Sung Hak; Hwang, Byoung Chul; Lee, Chang Gil

    2008-01-01

    This study is concerned with the effect of Cu and B addition on microstructure and mechanical properties of high-strength bainitic steels. Six kinds of steels were fabricated by varying alloying elements and hot-rolling conditions, and their microstructures and tensile and Charpy impact properties were investigated. Their effective grain sizes were also characterized by the electron back-scatter diffraction analysis. The tensile test results indicated that the B- or Cu-containing steels had the higher yield and tensile strengths than the B- or Cu-free steels because their volume fractions of bainitic ferrite and martensite were quite high. The B- or Cu-free steels had the higher upper shelf energy than the B- or Cu-containing steels because of their higher volume fraction of granular bainite. In the steel containing 10 ppm B without Cu, the best combination of high strengths, high upper shelf energy, and low energy transition temperature could be obtained by the decrease in the overall effective grain size due to the presence of bainitic ferrite having smaller effective grain size

  6. Characterization by notched and precracked Charpy tests of the in-service degradation of RPV steel fracture toughness

    Energy Technology Data Exchange (ETDEWEB)

    Fabry, A.

    1997-01-01

    The current engineering and regulatory practice to estimate fracture toughness safety margins for nuclear reactor pressure vessels (RPVs) relies heavily on the CVN impact test. Techniques to estimate in-service toughness degradation directly using a variety of precracked specimens are under development worldwide. Emphasis is on their miniaturization. In the nuclear context, it is essential to address many issues such as representativity of the surveillance programs with respect to the vessel in terms of materials and environment, transferability of test results to the structure (constraint and size effects), lower bound toughness certification, creadibility relative to trends of exising databases. An enhanced RPV surveillance strategy in under development in Belgium. It combines state-of-the-art micromechanical and damage modelling to the evaluation of CVN load-deflection signals, tensile stress-strain curves and slow-bend tests of reconstituted precracked Charpy specimens. A probabilistic micromechanical model has been established for static and dynamic transgranular cleavage initiation fracture toughness in the ductile-brittle transition temperature range. This model allows to project toughness bounds for any steel embrittlement condition from the corresponding CVN and static tensile properties, using a single scaling factor defined by imposing agreement with toughness tests in a single condition. The outstanding finding incorporated by this toughness transfer model is that the microcleavage fracture stress is affected by temperature in the ductile-brittle transition and that this influence is strongly correlated to the flow stress: this explains the shape of the K{sub Ic}n K{sub Id} temperature curves as well as the actual magnitude of the strain rate and irradiation effects. Furthermore, CVN crack arrest loads and fracture appearance are also taken advantage of in order to estimate K{sub Ia} degradation. Finally, the CVN-tensile load-temperature diagram

  7. Nuclear reactor pressure vessel surveillance capsule examinations. Application of American Society for Testing and Materials Standards

    International Nuclear Information System (INIS)

    Perrin, J.S.

    1978-01-01

    A series of pressure vessel surveillance capsules is installed in each commercial nuclear power plant in the United States. A capsule typically contains neutron dose meters, thermal monitors, tensile specimens, and Charpy V-notch impact specimens. In order to determine property changes of the pressure vessel resulting from irradiation, surveillance capsules are periodically removed during the life of a reactor and examined. There are numerous standards, regulations, and codes governing US pressure vessel surveillance capsule programmes. These are put out by the US Nuclear Regulatory Commission, the Boiler and Pressure Vessel Committee of the American Society of Mechanical Engineers, and the American Society for Testing and Materials (ASTM). A majority of the pertinent ASTM standards are under the jurisdiction of ASTM Committee E-10 on Nuclear Applications and Measurements of Radiation Effects. The standards, regulations, and codes pertaining to pressure vessel surveillance play an important role in ensuring reliability of the nuclear pressure vessels. ASTM E 185-73 is the Standard Recommended Practice for Surveillance Tests for Nuclear Reactors. This standard recommends procedures for both the irradiation and subsequent testing of surveillance capsules. ASTM E 185-73 references many additional specialized ASTM standards to be followed in specific areas of a surveillance capsule examination. A key element of surveillance capsule programmes is the Charpy V-notch impact test, used to define curves of fracture behaviour over a range of temperatures. The data from these tests are used to define the adjusted reference temperature used in determining pressure-temperature operating curves for a nuclear power plant. (author)

  8. Vía de señalización Notch y nuevas estrategias para el tratamiento de cáncer Notch signaling pathway and new strategies in cancer treatment

    Directory of Open Access Journals (Sweden)

    Leticia Santos

    2006-04-01

    Full Text Available La vía de señalización Notch desempeña un papel fundamental en las diferentes etapas del desarrollo celular como la proliferación, crecimiento, diferenciación y apoptosis. Estudios recientes han demostrado que, dependiendo del nivel de expresión y del contexto celular, los receptores de membrana Notch contribuyen en la resistencia a apoptosis en células tumorales. Estos descubrimientos sugieren que componentes de la vía de señalización Notch son un blanco potencial para el desarrollo de terapias más efectivas contra el cáncer. Esta revisión describe la función de la vía Notch y nuevas estrategias utilizadas en la modulación de su señal.The Notch signaling pathway plays a crucial role at different stages of cell development, such as proliferation, growth, differentiation, and apoptosis. Recent studies demonstrate that depending on the expression level and cellular context, the Notch receptors play a role in apoptosis resistance in malignant cells. These findings suggest that Notch signaling components may be a potential target in the development of new cancer therapies. This review describes the function of the Notch pathway and new strategies in the modulation of its signal.

  9. Change of notch impact strength depending on radiation dose and test temperature

    Directory of Open Access Journals (Sweden)

    Martin Bednarik

    2017-01-01

    Full Text Available The main purpose of this paper has been determine the effect of radiation crosslinking on the notch impact strength of polyamides filled with fiberglass. These properties were examined in dependence on the dosage of the ionizing beta radiation (non-irradiated samples and those irradiated by dosage 66 and 132 kGy were compared and on the test temperature (23–150 °C.

  10. Impact of Spectral Notch Width on Neurophysiological Plasticity and Clinical Effectiveness of the Tailor-Made Notched Music Training.

    Directory of Open Access Journals (Sweden)

    Robert Wunderlich

    Full Text Available Tinnitus, the ringing in the ears that is unrelated to any external source, causes a significant loss in quality of life, involving sleep disturbance and depression for 1 to 3% of the general population. While in the first place tinnitus may be triggered by damage to the inner ear cells, the neural generators of subjective tinnitus are located in central regions of the nervous system. A loss of lateral inhibition, tonotopical reorganization and a gain-increase in response to the sensory deprivation result in hypersensitivity and hyperactivity in certain regions of the auditory cortex. In the tailor-made notched music training (TMNMT patients listen to music from which the frequency spectrum of the tinnitus has been removed. This evokes strong lateral inhibition from neurons tuned to adjacent frequencies onto the neurons involved in the tinnitus percept. A reduction of tinnitus loudness and tinnitus-related neural activity was achieved with TMNMT in previous studies. As the effect of lateral inhibition depends on the bandwidth of the notch, in the current study we altered the notch width to find the most effective notch width for TMNMT. We compared 1-octave notch width with ½-octave and ¼-octave. Participants chose their favorite music for the training that included three month of two hours daily listening. The outcome was measured by means of standardized questionnaires and magnetoencephalography. We found a general reduction of tinnitus distress in all administered tinnitus questionnaires after the training. Additionally, tinnitus-related neural activity was reduced after the training. Nevertheless, notch width did not have an influence on the behavioral or neural effects of TMNMT. This could be due to a non-linear resolution of lateral inhibition in high frequencies.

  11. Feasibility of correlating V-Cr-Ti alloy weld strength with weld chemistry. CRADA final report

    International Nuclear Information System (INIS)

    Grossbeck, M.L.; Odom, R.W.

    1998-06-01

    The mechanical properties of refractory metals such as vanadium are determined to a large extent by the interstitial impurities in the alloy. In the case of welding, interstitial impurities are introduced in the welding process from the atmosphere and by dissolution of existing precipitates in the alloy itself. Because of the necessity of having an ultra-pure atmosphere, a vacuum chamber or a glove box is necessary. In the V-Cr-Ti system, the titanium serves as a getter to control the concentration of oxygen and nitrogen in solid solution in the alloy. In this project the secondary ion mass spectrometry (SIMS) technique was used to detect, measure, and map the spacial distribution of impurity elements in welds in the alloy V-4Cr-4Ti. An attempt was then made to correlate the concentrations and distributions of the impurities with mechanical properties of the welds. Mechanical integrity of the welds was determined by Charpy V-notch testing. Welds were prepared by the gas-tungsten-arc (GTA) method. Charpy testing established a correlation between weld impurity concentration and the ductile to brittle transition temperature (DBTT). Higher concentrations of oxygen resulted in a higher DBTT. An exception was noted in the case of a low-oxygen weld which had a high hydrogen concentration resulting in a brittle weld. The concentrations and distributions of the impurities determined by SIMS could not be correlated with the mechanical properties of the welds. This research supports efforts to develop fusion reactor first wall and blanket structural materials

  12. 46 CFR 154.605 - Toughness test.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Toughness test. 154.605 Section 154.605 Shipping COAST....605 Toughness test. (a) Each toughness test under §§ 154.610 through 154.625 must meet Subpart 54.05 of this chapter. (b) If subsize test specimens are used for the Charpy V-notch toughness test, the...

  13. Effects of anisotropic properties on bursting behavior of rectangular cup with a V-notch

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeong Tai [R and D Center, TERA Co. Ltd., Seoul (Korea, Republic of); Kim, Sang Mok [R and D Center, Hyosung Power and Industrial Systems PG, Changwon (Korea, Republic of); Kang, Beom Soo [Dept. of Aerospace Engineering, Pusan National University, Busan (Korea, Republic of); Ku, Tae Wan [Engineering Research Center of Innovative Technology on Advanced Forming, Pusan National University, Busan (Korea, Republic of)

    2016-09-15

    Effects of mechanical anisotropic properties on bursting failure and its pressure of rectangular deep-drawn cup fabricated by using AA3005-H14 thin sheet are investigated to utilize for electrolyte container of lithium-ion secondary batteries. The V-notch shape with a depth of 0.1 mm and an angle of 20.0 degrees is defined on the rectangular cup, which has a thickness of 0.20 mm on the major surface and that of 0.30 mm on the minor surface. With the measured mechanical properties by uni-axial tensile tests and the defined V-notch geometry, a series of numerical prediction models considering isotropic, planar and normal anisotropic characteristics, are built-up and the bursting simulations are performed. Thereafter, the bursting fracture behavior is investigated by adopting ductile fracture criterion proposed by Cockcroft and Latham. The results predicted for the planar and the normal anisotropic models show that the bursting fracture pressure is well matched to 0.400 MPa, and the isotropic and the planar anisotropic models present a bursting fracture height of about 4.95 mm and 4.92 mm, respectively. A series of experimental investigations are undertaken to verify the bursting deformation that had been predicted. The bursting pressure and its height during experimental verifications are shown to be in good agreement with each variation of about 5.88% and roughly 0.20% with respect to the numerical results obtained using the planar anisotropic model.

  14. Estimation of quasi-static J–R curves from Charpy energy and adaptation to ASTM E 1921 reference temperature estimation of ferritic steels

    International Nuclear Information System (INIS)

    Sreenivasan, P.R.

    2014-01-01

    Many researchers had suggested a sort of scaling procedure for predicting the quasi-static J–R curves from dynamic J–R curves obtained from instrumented Charpy V-notch (CVN) impact tests using key-curve, compliance or other procedures. Chaouadi, based on extensive tests and literature data, had quantitatively formalized the method and suggested general applicability of his method for a class of steels. In this paper, first, the Chauoadi-procedure is tried on some selected data from the literature (including the data used by Chaouadi and other workers) and an adaptation of the method is suggested using Wallin's as well as Landes's lower bound methods for upper-shelf J–R curve estimation from CVN energy. Using Chaouadi and other data as the benchmark, suitable scaling factors have been determined that enable estimation of quasi-static J–R curves from CVN energy alone, without the need for dynamic CVN J–R curves. The final formulae are given. This new method can be called modified Wallin–Landes procedure. Then this method is applied to fracture toughness and reference temperature (T 0 – ASTM E-1921) estimation from the full Charpy-transition data. The results are compared with those from the author's IGC-procedure, and modifications, if any, are suggested. Based on the new results, it is suggested that the IGC-procedure may be modified as: final T Q-est = T Q-IGC for T Q-Sch dy ≤ 20 °C (in the IGC-procedure the dividing temperature was 60 °C); and for T Q-Sch dy > 20 °C, T Q-IGC = T Q-WLm (different from the IGC-procedre and subscript WLm indicating modified Wallin–Landes procedure). For the 59 or more steels examined (including highly irradiated steels), the T Q-WL estimates at higher temperatures are consistent and conservative; a few non-conservative values are acceptably less than 20 °C, whereas other predictions show non-conservatism of up to 40–50 °C. At lower temperatures, T Q-IGC is consistently conservative and not over

  15. Estimation of quasi-static J–R curves from Charpy energy and adaptation to ASTM E 1921 reference temperature estimation of ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Sreenivasan, P.R., E-mail: sreeprs@yahoo.co.in

    2014-04-01

    Many researchers had suggested a sort of scaling procedure for predicting the quasi-static J–R curves from dynamic J–R curves obtained from instrumented Charpy V-notch (CVN) impact tests using key-curve, compliance or other procedures. Chaouadi, based on extensive tests and literature data, had quantitatively formalized the method and suggested general applicability of his method for a class of steels. In this paper, first, the Chauoadi-procedure is tried on some selected data from the literature (including the data used by Chaouadi and other workers) and an adaptation of the method is suggested using Wallin's as well as Landes's lower bound methods for upper-shelf J–R curve estimation from CVN energy. Using Chaouadi and other data as the benchmark, suitable scaling factors have been determined that enable estimation of quasi-static J–R curves from CVN energy alone, without the need for dynamic CVN J–R curves. The final formulae are given. This new method can be called modified Wallin–Landes procedure. Then this method is applied to fracture toughness and reference temperature (T{sub 0} – ASTM E-1921) estimation from the full Charpy-transition data. The results are compared with those from the author's IGC-procedure, and modifications, if any, are suggested. Based on the new results, it is suggested that the IGC-procedure may be modified as: final T{sub Q-est} = T{sub Q-IGC} for T{sub Q-Sch}{sup dy} ≤ 20 °C (in the IGC-procedure the dividing temperature was 60 °C); and for T{sub Q-Sch}{sup dy} > 20 °C, T{sub Q-IGC} = T{sub Q-WLm} (different from the IGC-procedre and subscript WLm indicating modified Wallin–Landes procedure). For the 59 or more steels examined (including highly irradiated steels), the T{sub Q-WL} estimates at higher temperatures are consistent and conservative; a few non-conservative values are acceptably less than 20 °C, whereas other predictions show non-conservatism of up to 40–50 °C. At lower temperatures

  16. Conclusions regarding fracture mechanics testing and evaluation of small specimens - As evidenced by the finnish contribution to the IAEA CRP3 programme

    Energy Technology Data Exchange (ETDEWEB)

    Wallin, K; Valo, M; Rintamaa, R; Torronen, K [Technical Research Centre of Finland, Espoo (Finland); Ahlstrand, R [Imatran Voima Oy (IVO), Helsinki (Finland)

    1994-12-31

    An extensive mechanical property evaluation has been carried out on various specimens (a Japanese steel plate (JRQ), a French forging material (FFA) and a Japanese forging material (JFL)) in the as-received and irradiated conditions. The mechanical properties measured at different temperatures include Charpy-V notch and instrumented pre-cracked Charpy data and static and dynamic elastic-plastic fracture toughness based on the J-integral, with various specimen size and geometry. Test analysis lead to conclusions regarding the use of small specimen fracture mechanical tests for investigating irradiation effects: CVN{sub pc} and RCT type specimens are suitable for determining the materials fracture toughness even in the ductile/brittle transition region provided the elastic-plastic parameter K{sub JC} is applied together with a statistical size correction. These two specimen types yield equivalent results for the fracture toughness transition shift. Charpy-V appears not to be suitable for estimating the static fracture toughness transition shift. 8 refs., 11 figs.

  17. Effect of multiple repairs in girth welds of pipelines on the mechanical properties

    International Nuclear Information System (INIS)

    Vega, O.E.; Hallen, J.M.; Villagomez, A.; Contreras, A.

    2008-01-01

    This work presents the results of multiple weld repairs in the same area in seamless API X-52 microalloyed steel pipe. Four conditions of shielded metal arc welding repairs and one as-welded specimen of the girth weld were characterized to determine changes in the microstructure, grain size in the heat affected zone, and to evaluate their effect on the mechanical properties of the weld joints. The mechanical properties by means of tension tests, Charpy-V impact resistance and Vickers hardness of the welds were analyzed. The results indicate that significant changes are not generated in the microstructural constituents of the heat affected zone. Grain growth in the heat affected zone at the specimen mid-thickness with the number of repairs was observed. Tensile strength of the weld joints meets the requirement of the API 1104 standard even after the fourth weld repair. Significant reduction in Charpy-V impact resistance with the number of weld repairs was found when the notch location was in the intersection of the fusion line with the specimen mid-thickness. A significant increase in the Vickers hardness of the heat affected zone occurred after the first repair and a gradual decrease in the Vickers hardness occurred as the number of repairs increases

  18. Effects of irradiation on strength and toughness of commercial LWR vessel cladding

    International Nuclear Information System (INIS)

    Haggag, F.M.; Corwin, W.R.; Alexander, D.J.; Nanstad, R.K.

    1987-01-01

    The potential for stainless steel cladding to improve the fracture behavior of an operating nuclear reactor pressure vessel, particularly during certain overcooling transients, may depend greatly on the properties of the irradiated cladding. Therefore, weld overlay cladding irradiated at temperatures and to fluences relevant to power reactor operation was examined. The cladding was applied to a pressure vessel steel plate by the three-wire series-arc commercial method. Cladding was applied in three layers to provide adequate thickness for the fabrication of test specimens. The three-wire series-arc procedure, developed by Combustion Engineering, Inc., Chattanooga, Tennessee, produced a highly controlled weld chemistry, microstructure, and fracture properties in all three layers of the weld. Charpy V-notch and tensile specimens were irradiated at 288 0 C to fluence levels of 2 and 5 x 10 19 neutrons/cm 2 (>1 MeV). Postirradiation testing results show that, in the test temperature range from -125 to 288 0 C, the yield strength increased by 8 to 30%, ductility insignificantly increased, while there was almost no change in ultimate tensile strength. All cladding exhibited ductile-to-brittle transition behavior during Charpy impact testing, due to the dominance of delta-ferrite failures at low temperatures. On the upper shelf, energy was reduced, due to irradiation exposure, 15 and 20%, while the lateral expansion was reduced 43 and 41%, at 2 and 5 x 10 19 neutrons/cm 2 (>1 MeV), respectively. In addition, radiation damage resulted in 13 and 28 0 C shifts of the Charpy impact transition temperature at the 41-J level for the low and high fluences, respectively

  19. Mechanical properties and examination of cracking in TMI-2 pressure vessel lower head material

    International Nuclear Information System (INIS)

    Diercks, D.R.; Neimark, L.A.

    1993-09-01

    Mechanical tests have been conducted on material from 15 samples removed from the lower head of the Three Mile Island unit 2 nuclear reactor pressure vessel. Measured properties include tensile properties and hardness profiles at room temperature, tensile and creep properties at temperatures of 600 to 1200 degrees C, and Charpy V-notch impact properties at -20 to +300 degrees C. These data, which were used in the subsequent analyses of the margin-to-failure of the lower head during the accident, are presented here. In addition, the results of metallographic and scanning electron microscope examinations of cladding cracking in three of the lower head samples are discussed

  20. Liability and lifetime of metallic components and structures

    International Nuclear Information System (INIS)

    Tanguy, B.

    2009-12-01

    In this overview of his research activity, the author describes the ductile damage process in structures subjected to high rate loadings, notably for tank steels and gas pipeline high resistance steels. Then, he describes the cleavage fracture process in bainitic steels by means of a local fracture approach. He proposes a modelling of the Charpy v-notch impact test of the resilience-to-toughness transition during the ductile-brittle transition for bainitic steels, the developed method being used to interpret resilience and toughness tests performed on an irradiated material. He finally discusses these works, describes the current ones, and discusses research perspectives within his Nuclear Material Department

  1. The adhesion force of Notch with Delta and the rate of Notch signaling.

    Science.gov (United States)

    Ahimou, Francois; Mok, Lee-Peng; Bardot, Boris; Wesley, Cedric

    2004-12-20

    Notch signaling is repeatedly used during animal development to specify cell fates. Using atomic force microscopy on live cells, chemical inhibitors, and conventional analyses, we show that the rate of Notch signaling is linked to the adhesion force between cells expressing Notch receptors and Delta ligand. Both the Notch extracellular and intracellular domains are required for the high adhesion force with Delta. This high adhesion force is lost within minutes, primarily due to the action of Presenilin on Notch. Reduced turnover or Delta pulling accelerate this loss. These data suggest that strong adhesion between Notch and Delta might serve as a booster for initiating Notch signaling at a high rate.

  2. Multivariable modeling of pressure vessel and piping J-R data

    International Nuclear Information System (INIS)

    Eason, E.D.; Wright, J.E.; Nelson, E.E.

    1991-05-01

    Multivariable models were developed for predicting J-R curves from available data, such as material chemistry, radiation exposure, temperature, and Charpy V-notch energy. The present work involved collection of public test data, application of advanced pattern recognition tools, and calibration of improved multivariable models. Separate models were fitted for different material groups, including RPV welds, Linde 80 welds, RPV base metals, piping welds, piping base metals, and the combined database. Three different types of models were developed, involving different combinations of variables that might be available for applications: a Charpy model, a preirradiation Charpy model, and a copper-fluence model. In general, the best results were obtained with the preirradiation Charpy model. The copper-fluence model is recommended only if Charpy data are unavailable, and then only for Linde 80 welds. Relatively good fits were obtained, capable of predicting the values of J for pressure vessel steels to with a standard deviation of 13--18% over the range of test data. The models were qualified for predictive purposes by demonstrating their ability to predict validation data not used for fitting. 20 refs., 45 figs., 16 tabs

  3. Weldability investigation steel P 91 by weld thermal cycle simulation

    Directory of Open Access Journals (Sweden)

    M. Dunđer

    2015-07-01

    Full Text Available This paper elaborates results of hardness and impact energy of thermal cycle simulated specimens of high-alloy steel P 91 and their dependence on cooling time from 800 to 500 °C. Results were obtained by measuring hardness HV 1 and by experimental testing of Charpy notched specimens. Metallographic analysis of samples was performed on scanning electronic microscope.

  4. Effect of Heat Treatment on Microstructure and Impact Toughness of Ti-6Al-4V Manufactured by Selective Laser Melting Process

    Directory of Open Access Journals (Sweden)

    Lee K.-A.

    2017-06-01

    Full Text Available This study manufactured Ti-6Al-4V alloy using one of the powder bed fusion 3D-printing processes, selective laser melting, and investigated the effect of heat treatment (650°C/3hrs on microstructure and impact toughness of the material. Initial microstructural observation identified prior-β grain along the building direction before and after heat treatment. In addition, the material formed a fully martensite structure before heat treatment, and after heat treatment, α and β phase were formed simultaneously. Charpy impact tests were conducted. The average impact energy measured as 6.0 J before heat treatment, and after heat treatment, the average impact energy increased by approximately 20% to 7.3 J. Fracture surface observation after the impact test showed that both alloys had brittle characteristics on macro levels, but showed ductile fracture characteristics and dimples at micro levels.

  5. Effects of boron addition on tensile and Charpy impact properties in high-phosphorous steels

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Seokmin; Lee, Junghoon [Center for Advanced Aerospace Materials, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Park, Kyong Su [Next Generation Products Research Group, Technical Research Laboratories, POSCO, Pohang 790-785 (Korea, Republic of); Lee, Sunghak, E-mail: shlee@postech.ac.kr [Center for Advanced Aerospace Materials, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

    2014-01-01

    In order to provide a new possibility for improving the steel-making productivity by fabricating plain carbon steels containing high phosphorous (P), effects of microstructures on tensile and Charpy impact properties were investigated in this study. Nine plain carbon steels were fabricated by controlling the addition of P and boron (B), and isothermal or quench heat-treatments were conducted on these steels to make ferrite–bainite-based or martensite-based microstructures. The addition of B positively influenced the grain refinement and the formation of bainites, thereby leading to the increase in strength. The upper shelf energy (USE) decreased with increasing P content, while the energy transition temperature (ETT) increased, in all the steels. The B addition beneficially affected both the USE and ETT as the dimpled ductile fracture mode prevailed in the B-added steels. This was because B preferentially covered grain boundaries, which reduced the grain boundary segregation of P. Thus, it effectively suppressed the intergranular fracture due to the segregation of P. According to the fractographic results, the increased tendency of intergranular fracture mode was observable in the 20-ppm-B-added steels rather than in the 10-ppm-B-added steels. When an excess amount of B, e.g., 20 ppm of B, was added, the severe segregation of B on grain boundaries occurred, and led to the precipitation of boro-carbides, which could act as intergranular crack initiation sites.

  6. Mechanical properties of 1950's vintage 304 stainless steel weldment components after low temperature neutron irradiation

    International Nuclear Information System (INIS)

    Sindelar, R.L.; Caskey, G.R. Jr.; Thomas, J.K.; Hawthorne, J.R.; Hiser, A.L.; Lott, R.A.; Begley, J.A.; Shogan, R.P.

    1991-01-01

    The reactor vessels of the nuclear production reactors at the Savannah River Site (SRS) were constructed in the 1950's from Type 304 stainless steel plates welded with Type 308 stainless steel filler using the multipass metal inert gas process. An irradiated mechanical properties database has been developed for the vessel with materials from archival primary coolant system piping irradiated at low temperatures (75 to 150 degrees C) in the State University of New York at Buffalo reactor (UBR) and the High Flux Isotope Reactor (HFIR) to doses of 0.065 to 2.1 dpa. Fracture toughness, tensile, and Charpy-V impact properties of the weldment components (base, weld, and weld heat-affected-zone (HAZ)) have been measured at temperatures of 25 degrees C and 125 degrees C in the L-C and C-L orientations for materials in both the irradiated and unirradiated conditions for companion specimens. Fracture toughness and tensile properties of specimens cut from an SRS reactor vessel sidewall with doses of 0.1 and 0.5 dpa were also measured at temperatures of 25 and 125 degrees C. The irradiated materials exhibit hardening with loss of work hardenability and a reduction in toughness relative to the unirradiated materials. The HFIR-irradiated materials show an increase in yield strength between about 20% and 190% with a concomitant tensile strength increase between about 15% to 30%. The elastic-plastic fracture toughness parameters and Charpy-V energy absorption both decrease and show only a slight sensitivity to dose. The irradiation-induced decrease in the elastic-plastic fracture toughness (J def at 1 mm crack extension) is between 20% to 65%; the range of J 1C values are 72.8 to 366 kJ/m 2 for the irradiated materials. Similarly, Charpy V-notch results show a 40% to 60% decrease in impact energies

  7. Characteristics of the IAEA correlation monitor material for surveillance programmes

    International Nuclear Information System (INIS)

    Wallin, K.; Valo, M.; Rintamaa, R.; Toerroenen, K.

    1989-08-01

    Within the IAEA Coordinated Research Programme on optimizing of reactor pressure vessel surveillance programmes and their analysis, phase 3, a specially tailored 'radiation sensitive' correlation monitor material has been fabricated. This material will serve as a reference to the IAEA programme for future vessel surveillance programmes throughout the world. An extensive evaluation of the correlation monitor material in the as-received condition has been carried out in Finland and the results are presented here. The mechanical properties measured at different temperatures include Charpy V notch and instrumented precracked Charpy data, and elastic-plastic fracture toughness (J). The specimen size and geometry have been varied in the tests. Correlation between different fracture properties are evaluated and discussed

  8. Verification of the effect of surface preparation on Hot Isostatic Pressing diffusion bonding joints of CLAM steel

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yanyun [University of Science and Technology of China, Hefei, Anhui 230027 (China); Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Li, Chunjing, E-mail: chunjing.li@fds.org.cn [Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Huang, Bo; Liu, Shaojun [Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Huang, Qunying [University of Science and Technology of China, Hefei, Anhui 230027 (China); Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China)

    2014-12-15

    Hot Isostatic Pressing (HIP) diffusion bonding with CLAM steel is the primary candidate fabrication technique for the first wall (FW) of DFLL-TBM. Surface state is one of the key factors for the joints quality. The effect of surface state prepared with grinder and miller on HIP diffusion bonding joints of CLAM steel was investigated. HIP diffusion bonding was performed at 140 MPa and 1373 K within 3 h. The mechanical properties of the joints were investigated with instrumented Charpy V-notch impact tests and the microstructures of the joints were analyzed with scanning electron microscopy (SEM). The results showed that the milled samples with fine surface roughness were more suitable for CLAM steel HIP diffusion bonding.

  9. Review of in-service thermal annealing of nuclear reactor pressure vessels

    International Nuclear Information System (INIS)

    Server, W.L.

    1984-01-01

    Radiation embrittlement of ferritic pressure vessel steels increases the ductile-brittle transition temperature and decreases the upper-shelf level of toughness as measured by Charpy impact tests. A thermal anneal cycle well above the normal operating temperature of the vessel can restore most of the original Charpy V-notch energy properties. A test reactor pressure vessel has been wet annealed at less than 343 0 C (650 0 F), and annealing of the Belgian BR-3 reactor vessel has recently taken place. An industry survey indicates that dry annealing a reactor vessel in-place is feasible, but solvable engineering problems do exist. The materials with highest radiation sensitivity in the older reactor vessels are submerged-arc weld metals with high copper and nickel concentrations. The limited Charpy V-notch and fracture toughness data available for five such welds were reviewed. The review suggested that significant recovery results from annealing at 454 0 C (850 0 F) for one week. Two of the main concerns with a localized heat treatment at 454 0 C (850 0 F) are the degree of distortion that may occur after the annealing cycle and the extent of residual stresses. A thermal and structural analysis of a reactor vessel for distortions and residual stresses found no problems with the reactor vessel itself but did indicate a rotation at the nozzle region of the vessel that would plastically deform the attached primary piping. Further analytical studies are needed. An American Society for Testing and Materials (ASTM) task group is upgrading and revising the ASTM Recommended Guide for In-Service Annealing of WaterCooled Nuclear Reactor Vessels (E 509-74) with emphasis on the materials and surveillance aspects of annealing rather than system engineering problems. System safety issues are the province of organizations other than ASTM (for example, the American Society of Mechanical Engineers Boiler and Pressure Vessel Code body)

  10. Effect on fast neutron irradiation to 4 dpa at 400{degrees}C on the properties of V-(4-5)Cr-(4-5)Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J.; Alexander, D.J.; Robertson, J.P. [Oak Ridge National Lab., TN (United States)] [and others

    1997-04-01

    Tensile, Charpy impact and electrical resistivity measurements have been performed at ORNL on V-4Cr-4Ti and V-5Cr-5Ti specimens that were prepared at ANL and irradiated in the lithium-bonded X530 experiment in the EBR-II fast reactor. All of the specimens were irradiated to a damage level of about 4 dpa at a temperature of {approximately}400{degrees}C. A significant amount of radiation hardening was evident in both the tensile and Charpy impact tests. The irradiated V-4Cr-4Ti yield strength measured at {approximately}390{degrees}C was >800 MPa, which is more than three times as high as the unirradiated value. The uniform elongations of the irradiated tensile specimens were typically {approximately}1%, with corresponding total elongations of 4-6%. The ductile to brittle transition temperature of the irradiated specimens was less than the unirradiated resistivity, which suggests that hardening associated with interstitial solute pickup was minimal.

  11. A reassessment of the effects of helium on Charpy impact properties of ferritic/martensitic steels

    International Nuclear Information System (INIS)

    Gelles, D.S.; Hamilton, M.L.; Hankin, G.L.

    1998-01-01

    To test the effect of helium on Charpy impact properties of ferritic/martensitic steels, two approaches are reviewed: quantification of results of tests performed on specimens irradiated in reactors with very different neutron spectra, and isotopic tailoring experiments. Data analysis can show that if the differences in reactor response are indeed due to helium effects, then irradiation in a fusion machine at 400 C to 100 dpa and 1000 appm He will result in a ductile to brittle transition temperature shift of over 500 C. However, the response as a function of dose and helium level is unlikely to be simply due to helium based on physical reasoning. Shear punch tests and microstructural examinations also support this conclusion based on irradiated samples of a series of alloys made by adding various isotopes of nickel in order to vary the production of helium during irradiation in HFIR. The addition of nickel at any isotopic balance to the Fe-12Cr base alloy significantly increased the shear yield and maximum strengths of the alloys. However, helium itself, up to 75 appm at over 7 dpa appears to have little effect on the mechanical properties of the alloys. This behavior is instead understood to result from complex precipitation response. The database for effects of helium on embrittlement based on nickel additions is therefore probably misleading and experiments should be redesigned to avoid nickel precipitation

  12. A perspective on thermal annealing of reactor pressure vessel materials from the viewpoint of experimental results

    International Nuclear Information System (INIS)

    Iskander, S.K.; Sokolov, M.A.; Nanstad, R.K.

    1996-01-01

    It is believed that in the next decade or so, several nuclear reactor pressure vessels (RPVs) may exceed the reference temperature limits set by the pressurized thermal shock screening criteria. One of the options to mitigate the effects of irradiation on RPVs is to thermally anneal them to restore the toughness properties that have been degraded by neutron irradiation. This paper summarizes recent experimental results from work performed at the Oak Ridge National Laboratory to study the annealing response, or ''recovery'' of several irradiated RPV steels. The fracture toughness is one of the important properties used in the evaluation of the integrity of RPVs. Optimally, the fracture toughness is measured directly by fracture toughness specimens, such as compact tension or precracked Charpy specimens, but is often inferred from the results of Charpy V-notch impact specimens. The experimental results are compared to the predictions of models for embrittlement recovery which have been developed by Eason et al. Some of the issues in annealing that still need to be resolved are discussed

  13. 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.

  14. The common oncogenomic program of NOTCH1 and NOTCH3 signaling in T-cell acute lymphoblastic leukemia.

    Directory of Open Access Journals (Sweden)

    Sung Hee Choi

    Full Text Available Notch is a major oncogenic driver in T cell acute lymphoblastic leukemia (T-ALL, in part because it binds to an enhancer that increases expression of MYC. Here, we exploit the capacity of activated NOTCH1 and NOTCH3 to induce T-ALL, despite substantial divergence in their intracellular regions, as a means to elucidate a broad, common Notch-dependent oncogenomic program through systematic comparison of the transcriptomes and Notch-bound genomic regulatory elements of NOTCH1- and NOTCH3-dependent T-ALL cells. ChIP-seq studies show a high concordance of functional NOTCH1 and NOTCH3 genomic binding sites that are enriched in binding motifs for RBPJ, the transcription factor that recruits activated Notch to DNA. The interchangeability of NOTCH1 and NOTCH3 was confirmed by rescue of NOTCH1-dependent T-ALL cells with activated NOTCH3 and vice versa. Despite remarkable overall similarity, there are nuanced differences in chromatin landscapes near critical common Notch target genes, most notably at a Notch-dependent enhancer that regulates MYC, which correlates with responsiveness to Notch pathway inhibitors. Overall, a common oncogenomic program driven by binding of either Notch is sufficient to maintain T-ALL cell growth, whereas cell-context specific differences appear to influence the response of T-ALL cells to Notch inhibition.

  15. Toughness testing and high-temperature oxidation evaluations of advanced alloys for core internals

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Lizhen [ORNL; Pint, Bruce A [ORNL; Chen, Xiang [ORNL

    2016-09-16

    Alloy X-750 was procured from Carpenter Technology and Bodycote in this year. An appropriate TMT was developed on Alloy 439 to obtain materials with refined grain size for property screening tests. Charpy V-notch impact tests were completed for the three ferritic steels Grade 92, Alloy 439, and 14YWT. Fracture toughness tests at elevated temperatures were completed for 14YWT. The tests will be completed for the other alloys in next fiscal year. Steam oxidation tests of the three ferritic steels, 316L, and Zr–2.5Nb have been completed. The steam tests of the Ni-based superalloys and the other austenitic stainless steels will be continued and finished in next fiscal year. Performance ranking in terms of steam oxidation resistance and impact/fracture toughness of the alloys will be deduced.

  16. Significance of Charpy and COD tests in the determination of fracture toughness of welds

    International Nuclear Information System (INIS)

    Caminha Junior, H.M.; Bastian, F.L.

    1983-01-01

    A comparison is made between the Charpy and crack opening displacement (COD) tests used to acess the fracture toughness of metallic materials. The main problems inherent in these tests are discussed, such as scatter of results and their advantages and limitations. The chief experimental difficulties when they are applied to welds are indicated and the various methods available for calculating the COD from a test graph are described. Comments are made on the use of the Charpy test and the methods of calculating the COD in determing critical defect sizes in welded structures. (Author) [pt

  17. Effect of He implantation on fracture behavior and microstructural evolution in F82H

    Energy Technology Data Exchange (ETDEWEB)

    Yabuuchi, Kiyohiro, E-mail: kiyohiro.yabuuchi@qse.tohoku.ac.jp [Department of Quantum Science and Energy Engineering, Tohoku University, 6-6-01-2, Aramaki-Aza-Aoba, Aobaku, Sendai, Miyagi 980-8579 (Japan); Sato, Kiminori; Nogami, Shuhei; Hasegawa, Akira [Department of Quantum Science and Energy Engineering, Tohoku University, 6-6-01-2, Aramaki-Aza-Aoba, Aobaku, Sendai, Miyagi 980-8579 (Japan); Ando, Masami; Tanigawa, Hiroyasu [Japan Atomic Energy Agency, 2-166, Oaza-Obuchi-Aza-Omotedate, Rokkasho-mura, Kamikita-gun, Aomori 039-3212 (Japan)

    2014-12-15

    Reduced-activation ferritic/martensitic steels (RAFMs) are the primary candidate structural materials for fusion reactor blanket components. He bubbles, which formed under 14 MeV neutron irradiation, is considered to cause some mechanical property changes. In a previous study, Hasegawa et al. investigated the fracture behavior using Charpy impact test of He implanted F82H by 50 MeV α-particles with cyclotron accelerator, and the ductile brittle transition temperature (DBTT) was increased and intergranular fracture (IGF) was observed. However, the cause of the IGF was not shown in the previous study. To clarify the cause of the IGF of the He implanted F82H by 50 MeV α-particles with cyclotron accelerator, the microstructure of the He implanted F82H was investigated. After Charpy impact test at 233 K, the brittle fracture surface of the He implanted specimen was observed by SEM and TEM. By SEM observation, grain boundary surface was clearly observed from the bottom of the notch to a depth of about 400 μm. This area correspond to the He implanted region. On the other hand, at unimplanted region, river pattern was observed and transgranular fracture occurred. TEM observation revealed the He bubbles agglomeration at dislocations, lath boundaries, and grain boundaries, and the coarsening of precipitates on grain boundaries. IGF of the He implanted F82H was caused by both He bubbles and coarsening precipitates.

  18. Perivascular delivery of Notch 1 siRNA inhibits injury-induced arterial remodeling.

    Directory of Open Access Journals (Sweden)

    Eileen M Redmond

    Full Text Available To determine the efficacy of perivascular delivery of Notch 1 siRNA in preventing injury-induced arterial remodeling.Carotid artery ligation was performed to induce arterial remodeling. After 14 days, morphometric analysis confirmed increased vSMC growth and subsequent media thickening and neointimal formation. Laser capture microdissection, quantitative qRT-PCR and immunoblot analysis of medial tissue revealed a significant increase in Notch1 receptor and notch target gene, Hrt 1 and 2 expression in the injured vessels. Perivascular delivery of Notch 1 siRNA by pluronic gel inhibited the injury-induced increase in Notch 1 receptor and target gene expression when compared to scrambled siRNA controls while concomitantly reducing media thickening and neointimal formation to pre-injury, sham-operated levels. Selective Notch 1 knockdown also reversed the injury-induced inhibition of pro-apoptotic Bax expression while decreasing injury-induced anti-apoptotic Bcl-XL expression to sham-operated control levels. In parallel experiments, proliferative cyclin levels, as measured by PCNA expression, were reversed to sham-operated control levels following selective Notch 1 knockdown.These results suggest that injury-induced arterial remodeling can be successfully inhibited by localized perivascular delivery of Notch 1 siRNA.

  19. Frequency and distribution of Notch mutations in tumor cell lines

    International Nuclear Information System (INIS)

    Mutvei, Anders Peter; Fredlund, Erik; Lendahl, Urban

    2015-01-01

    Deregulated Notch signaling is linked to a variety of tumors and it is therefore important to learn more about the frequency and distribution of Notch mutations in a tumor context. In this report, we use data from the recently developed Cancer Cell Line Encyclopedia to assess the frequency and distribution of Notch mutations in a large panel of cancer cell lines in silico. Our results show that the mutation frequency of Notch receptor and ligand genes is at par with that for established oncogenes and higher than for a set of house-keeping genes. Mutations were found across all four Notch receptor genes, but with notable differences between protein domains, mutations were for example more prevalent in the regions encoding the LNR and PEST domains in the Notch intracellular domain. Furthermore, an in silico estimation of functional impact showed that deleterious mutations cluster to the ligand-binding and the intracellular domains of NOTCH1. For most cell line groups, the mutation frequency of Notch genes is higher than in associated primary tumors. Our results shed new light on the spectrum of Notch mutations after in vitro culturing of tumor cells. The higher mutation frequency in tumor cell lines indicates that Notch mutations are associated with a growth advantage in vitro, and thus may be considered to be driver mutations in a tumor cell line context. The online version of this article (doi:10.1186/s12885-015-1278-x) contains supplementary material, which is available to authorized users

  20. Characterization and analysis of surface notches on Ti-alloy plates fabricated by additive manufacturing techniques

    Science.gov (United States)

    Chan, Kwai S.

    2015-12-01

    Rectangular plates of Ti-6Al-4V with extra low interstitial (ELI) were fabricated by layer-by-layer deposition techniques that included electron beam melting (EBM) and laser beam melting (LBM). The surface conditions of these plates were characterized using x-ray micro-computed tomography. The depth and radius of surface notch-like features on the LBM and EBM plates were measured from sectional images of individual virtual slices of the rectangular plates. The stress concentration factors of individual surface notches were computed and analyzed statistically to determine the appropriate distributions for the notch depth, notch radius, and stress concentration factor. These results were correlated with the fatigue life of the Ti-6Al-4V ELI alloys from an earlier investigation. A surface notch analysis was performed to assess the debit in the fatigue strength due to the surface notches. The assessment revealed that the fatigue lives of the additively manufactured plates with rough surface topographies and notch-like features are dominated by the fatigue crack growth of large cracks for both the LBM and EBM materials. The fatigue strength reduction due to the surface notches can be as large as 60%-75%. It is concluded that for better fatigue performance, the surface notches on EBM and LBM materials need to be removed by machining and the surface roughness be improved to a surface finish of about 1 μm.

  1. Characterization and analysis of surface notches on Ti-alloy plates fabricated by additive manufacturing techniques

    International Nuclear Information System (INIS)

    Chan, Kwai S.

    2015-01-01

    Rectangular plates of Ti–6Al–4V with extra low interstitial (ELI) were fabricated by layer-by-layer deposition techniques that included electron beam melting (EBM) and laser beam melting (LBM). The surface conditions of these plates were characterized using x-ray micro-computed tomography. The depth and radius of surface notch-like features on the LBM and EBM plates were measured from sectional images of individual virtual slices of the rectangular plates. The stress concentration factors of individual surface notches were computed and analyzed statistically to determine the appropriate distributions for the notch depth, notch radius, and stress concentration factor. These results were correlated with the fatigue life of the Ti–6Al–4V ELI alloys from an earlier investigation. A surface notch analysis was performed to assess the debit in the fatigue strength due to the surface notches. The assessment revealed that the fatigue lives of the additively manufactured plates with rough surface topographies and notch-like features are dominated by the fatigue crack growth of large cracks for both the LBM and EBM materials. The fatigue strength reduction due to the surface notches can be as large as 60%–75%. It is concluded that for better fatigue performance, the surface notches on EBM and LBM materials need to be removed by machining and the surface roughness be improved to a surface finish of about 1 μm. (paper)

  2. Effect of groove design on mechanical and metallurgical properties of quenched and tempered low alloy abrasion resistant steel welded joints

    International Nuclear Information System (INIS)

    Sharma, Varun; Shahi, A.S.

    2014-01-01

    Highlights: • Effect of weld groove design on Q and T steel welded joints is investigated. • Groove design influences heat dissipation characteristics of welded joints. • Double-V groove joint possesses maximum yield strength and UTS. • C-groove joint possesses highest impact energy, both at room temperature and 0 °C. • A wide variation in microhardness exists across different zone of the weldments. - Abstract: Experimental investigations were carried out to study the influence of three different groove designs on mechanical and metallurgical properties of 15 mm thick Q and T (quenched and tempered) steel welded joints. Welding heat input variation corresponding to each joint configuration was kept to a minimal such that the objective of investigating, exclusively, the effect of varied weld volume on the mechanical and metallurgical performance of these joints could be accomplished. Mechanical performance of these joints was evaluated by subjecting them to transverse tensile testing, and Charpy V-notch impact testing of the weld zones at room temperature and 0 °C. The results of this study reveal that among all types of groove formations used for welding, double-V groove joint possessed maximum YS (yield strength) and UTS (ultimate tensile strength), besides maximum strength ratio (YS/UTS) that was followed by U-groove joint and C-groove joint, respectively. However, weld zone tested individually, for the cover as well as the root pass of the C-groove joint possessed highest CVN (Charpy V-notch) values, both at room temperature and 0 °C. Extensive microhardness studies of these weldments showed a wide variation in the microhardness values of the weld zone and the HAZ (heat affected zone). It was concluded that each groove formation/design exerted a significant influence on the heat dissipation characteristics of these joints, which is evident from different morphological features as revealed through optical microscopy. Scanning electron microscopic

  3. Methods and devices for small specimen testing at the Japan Atomic Energy Research Institute

    International Nuclear Information System (INIS)

    Jitsukawa, Shiro; Kizaki, Minoru; Umino, Akira; Shiba, Kiyoyuki; Hishinuma, Akimichi

    1993-01-01

    Devices for a punch test on annular notched specimens, small punch (SP) tests, and miniaturized tension tests in hot cells were developed. A micro-manipulator to handle small specimens and an electro-discharge machine (EDM) to extract miniaturized tension specimens and annular notched specimens from transmission electron microscopy (TEM) disks were also fabricated. These devices were designed and made for remote operation in hot cells. Preliminary tests to evaluate the applicability of test methods were carried out. Correlation between SP test results and tensile properties was not strong. Miniaturized tensile results were reasonably similar to the results with larger specimens. The ductile-brittle transition temperature (DBTT) by the punch test on annular notched specimens was higher than that obtained from the SP test. However, materials dependence of the DBTT was different from that measured by standard Charpy V-notch (CVN) tests. This may be due to a specimen size effect

  4. Conditions for crack initiation in an orthotropic bi-material notch

    Czech Academy of Sciences Publication Activity Database

    Klusák, Jan; Profant, T.; Kotoul, M.

    2012-01-01

    Roč. 19, č. 4 (2012), s. 302-307 ISSN 1537-6494 R&D Projects: GA ČR GA101/08/0994; GA ČR GAP108/10/2049 Institutional support: RVO:68081723 Keywords : General singular stress concentrators * Fracture mechanics * Notch es * Bi-material notch es * Fracture mechanics Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 0.701, year: 2012

  5. Endosomal sorting of Notch receptors through COMMD9-dependent pathways modulates Notch signaling

    NARCIS (Netherlands)

    Li, Haiying; Koo, Yeon; Mao, Xicheng; Sifuentes-Dominguez, Luis; Morris, Lindsey L.; Jia, Da; Miyata, Naoteru; Faulkner, Rebecca A.; van Deursen, Jan M.; Vooijs, Marc; Billadeau, Daniel D.; van de Sluis, Bart; Cleaver, Orane; Burstein, Ezra

    2015-01-01

    Notch family members are transmembrane receptors that mediate essential developmental programs. Upon ligand binding, a proteolytic event releases the intracellular domain of Notch, which translocates to the nucleus to regulate gene transcription. In addition, Notch trafficking across the

  6. SCK-CEN Contribution to the''Relation between different measures of exposure-induced shifts in ductile-brittle transition temperatures'' (REFEREE). Progress Report

    International Nuclear Information System (INIS)

    Chaouadi, R.; Van Walle, E.; Fabry, A.; Puzzolante, J.L.

    1998-08-01

    The relationship between Charpy-V (CVN) impact, fracture toughness and tensile properties for selected reactor pressure -vessel steels in the transition temperature range are investigated. Data on the testing of unirradiated material are reported. The applied methods include chemical analysis, Charpy-V impact testing, tensile testing and fracture toughness determination

  7. The adhesion force of Notch with Delta and the rate of Notch signaling

    OpenAIRE

    Ahimou, Francois; Mok, Lee-Peng; Bardot, Boris; Wesley, Cedric

    2004-01-01

    Notch signaling is repeatedly used during animal development to specify cell fates. Using atomic force microscopy on live cells, chemical inhibitors, and conventional analyses, we show that the rate of Notch signaling is linked to the adhesion force between cells expressing Notch receptors and Delta ligand. Both the Notch extracellular and intracellular domains are required for the high adhesion force with Delta. This high adhesion force is lost within minutes, primarily due to the action of ...

  8. Illegitimate V(D)J recombination-mediated deletions in Notch1 and Bcl11b are not sufficient for extensive clonal expansion and show minimal age or sex bias in frequency or junctional processing

    Energy Technology Data Exchange (ETDEWEB)

    Champagne, Devin P., E-mail: devin.champagne@uvm.edu; Shockett, Penny E., E-mail: pshockett@selu.edu

    2014-03-15

    Highlights: • Examines illegitimate V(D)J deletion junctions in Notch1 and Bcl11b. • Suggests little influence of deletions alone on clonal outgrowth in wild-type mice. • No age or sex biases in frequency, clonality, or junctional processing observed. • Contrasts with previous results at TCRβ and HPRT1 loci. • Deletions in Bcl11b may be tolerated more easily than those in Notch1. - Abstract: Illegitimate V(D)J recombination at oncogenes and tumor suppressor genes is implicated in formation of several T cell malignancies. Notch1 and Bcl11b, genes involved in developing T cell specification, selection, proliferation, and survival, were previously shown to contain hotspots for deletional illegitimate V(D)J recombination associated with radiation-induced thymic lymphoma. Interestingly, these deletions were also observed in wild-type animals. In this study, we conducted frequency, clonality, and junctional processing analyses of Notch1 and Bcl11b deletions during mouse development and compared results to published analyses of authentic V(D)J rearrangements at the T cell receptor beta (TCRβ) locus and illegitimate V(D)J deletions observed at the human, nonimmune HPRT1 locus not involved in T cell malignancies. We detect deletions in Notch1 and Bcl11b in thymic and splenic T cell populations, consistent with cells bearing deletions in the circulating lymphocyte pool. Deletions in thymus can occur in utero, increase in frequency between fetal and postnatal stages, are detected at all ages examined between fetal and 7 months, exhibit only limited clonality (contrasting with previous results in radiation-sensitive mouse strains), and consistent with previous reports are more frequent in Bcl11b, partially explained by relatively high Recombination Signal Information Content (RIC) scores. Deletion junctions in Bcl11b exhibit greater germline nucleotide loss, while in Notch1 palindromic (P) nucleotides are more abundant, although average P nucleotide length is

  9. Notch constraint effects on the dynamic fracture toughness of an unaged beta titanium alloy

    International Nuclear Information System (INIS)

    Rack, H.J.

    1975-01-01

    The influence of notch included angle and root radius on the apparent dynamic fracture toughness of an unaged metastable beta titanium alloy, Ti--3Al--8V--6Cr--4Zr--4Mo, has been examined. The apparent fracture toughness, K/sub Id/(rho), increases with both notch radius, rho and included angle, ω. These results have been compared with the theoretical predictions of Tetelman, et al. and Smith. The comparisons show that neither theory accurately describes the effect of varying notch constraint on the apparent dynamic fracture toughness. Although preliminary considerations indicate that qualitative descriptions of notch acuity effects may be given by recent finite element analysis of the stress and strain distributions below a notch root, there is presently no quantitative basis for determining the true dynamic fracture toughness of materials from the results of blunt notch experiments. (auth)

  10. SISTEMA DE AQUISIÇÃO DE DADOS PARA A MÁQUINA DE IMPACTO CHARPY

    Directory of Open Access Journals (Sweden)

    Jermana Lopes Moraes

    2014-08-01

    Full Text Available Este trabalho tem o objetivo de implementar e desenvolver um sistema de aquisição de dados para a máquina de impacto Charpy. Assim, é realizado um estudo da máquina de impacto Charpy, do ensaio de impacto e das ferramentas necessárias para desenvolvimento do projeto. Utiliza-se um acelerômetro para determinar a aceleração nos eixos x e y do pêndulo Charpy durante a realização do ensaio. Para leitura e interpretação dos dados enviados pelo acelerômetro utiliza-se a plataforma de hardware Arduino UNO com software específico. Os dados enviados ao Arduino são apresentados em uma interface gráfica desenvolvida no Matlab. Nesta interface é possível inserir os dados iniciais de ensaio Charpy e apresentar ao usuário final os resultados finais de ensaio, como a energia de impacto, a resistência de impacto e a força necessária para romper o corpo de prova. Além disso, é apresentado ao usuário um gráfico da aceleração ao longo da realização do ensaio e o gráfico de força ao longo do tempo. Desta forma, registram-se os dados em um arquivo específico para análise e estudo posterior. A porcentagem de erro entre o valor medidor no mostrador da máquina e o resultado automatizado não ultrapassa o limite de 8 %.

  11. Characterization of Notch1 antibodies that inhibit signaling of both normal and mutated Notch1 receptors.

    Directory of Open Access Journals (Sweden)

    Miguel Aste-Amézaga

    2010-02-01

    Full Text Available Notch receptors normally play a key role in guiding a variety of cell fate decisions during development and differentiation of metazoan organisms. On the other hand, dysregulation of Notch1 signaling is associated with many different types of cancer as well as tumor angiogenesis, making Notch1 a potential therapeutic target.Here we report the in vitro activities of inhibitory Notch1 monoclonal antibodies derived from cell-based and solid-phase screening of a phage display library. Two classes of antibodies were found, one directed against the EGF-repeat region that encompasses the ligand-binding domain (LBD, and the second directed against the activation switch of the receptor, the Notch negative regulatory region (NRR. The antibodies are selective for Notch1, inhibiting Jag2-dependent signaling by Notch1 but not by Notch 2 and 3 in reporter gene assays, with EC(50 values as low as 5+/-3 nM and 0.13+/-0.09 nM for the LBD and NRR antibodies, respectively, and fail to recognize Notch4. While more potent, NRR antibodies are incomplete antagonists of Notch1 signaling. The antagonistic activity of LBD, but not NRR, antibodies is strongly dependent on the activating ligand. Both LBD and NRR antibodies bind to Notch1 on human tumor cell lines and inhibit the expression of sentinel Notch target genes, including HES1, HES5, and DTX1. NRR antibodies also strongly inhibit ligand-independent signaling in heterologous cells transiently expressing Notch1 receptors with diverse NRR "class I" point mutations, the most common type of mutation found in human T-cell acute lymphoblastic leukemia (T-ALL. In contrast, NRR antibodies failed to antagonize Notch1 receptors bearing rare "class II" or "class III" mutations, in which amino acid insertions generate a duplicated or constitutively sensitive metalloprotease cleavage site. Signaling in T-ALL cell lines bearing class I mutations is partially refractory to inhibitory antibodies as compared to cell

  12. Visual interface for the automation of the instrumented pendulum of Charpy tests used in the surveillance program of reactors vessel of nuclear power plants; Interfase visual para la automatizacion del pendulo instrumentado de pruebas Charpy utilizado en el programa de vigilancia de la vasija de reactores de centrales nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Rojas S, A.S.; Sainz M, E.; Ruiz E, J.A. [ININ, Carretera Mexico-Toluca Km.36.5, Mpio. de Ocoyoacac, Estado de Mexico (Mexico)]. E-mail: asrs@nuclear.inin.mx; esm@nuclear.inin.mx; jare@nuclear.inin.mx

    2004-07-01

    Inside the Programs of Surveillance of the nuclear power stations periodic information is required on the state that keep the materials with those that builds the vessel of the reactor. This information is obtained through some samples or test tubes that are introduced inside the core of the reactor and it is observed if its physical characteristics remain after having been subjected to the radiation changes and temperature. The rehearsal with the instrumented Charpy pendulum offers information on the behavior of fracture dynamics of a material. In the National Institute of Nuclear Research (ININ) it has an instrumented Charpy pendulum. The operation of this instrument is manual, having inconveniences to carry out rehearsals with radioactive material, handling of high and low temperatures, to fulfill the normative ones for the realization of the rehearsals, etc. In this work the development of a computational program is presented (virtual instrument), for the automation of the instrumented pendulum. The system has modules like: Card of data acquisition, signal processing, positioning system, tempered system, pneumatic system, compute programs like it is the visual interface for the operation of the instrumented Charpy pendulum and the acquisition of impact signals. This system shows that given the characteristics of the nuclear industry with radioactive environments, the virtual instrumentation and the automation of processes can contribute to diminish the risks to the personnel occupationally exposed. (Author)

  13. A survey of tests for protection against non-ductile failure

    International Nuclear Information System (INIS)

    Girotra, C.C.

    1975-01-01

    A study of the various tests available to test susceptibility to brittle fracture - their advantages, limitations has been made and the present status of data available to engineers has been surveyed. Due to the limitations of the charpy V-notch impact testing method - LEFM based Ksub(Ic) test and GYFM based COD test have been receiving recognition. ASME Section III has recently recommended Ksub(Ic) test as an alternative test for the selection of (ferritic) materials for class 1 pressure vessels. COD test proposed by British research workers, however, is yet to gain recognition for pressure vessel code particles, although it has existed as a tentative specification for more than 2 years and is more relevant to the materials with average strength. (author)

  14. Fractographic examination of reduced activation ferritic/martensitic steel charpy specimens irradiated to 30 dpa at 370{degrees}C

    Energy Technology Data Exchange (ETDEWEB)

    Gelles, D.S.; Hamilton, M.L. [Pacific Northwest National Lab., Richland, WA (United States); Schubert, L.E. [Univ. of Missouri, Rolla, MO (United States)

    1996-10-01

    Fractographic examinations are reported for a series of reduced activation ferritic/Martensitic steel Charpy impact specimens tested following irradiation to 30 dpa at 370{degrees}C in FFTF. One-third size specimens of six low activation steels developed for potential application as structural materials in fusion reactors were examined. A shift in brittle fracture appearance from cleavage to grain boundary failure was noted with increasing manganese content. The results are interpreted in light of transmutation induced composition changes in a fusion environment.

  15. Influence of Loading Rate on the Calibration of Instrumented Charpy Strikers

    Energy Technology Data Exchange (ETDEWEB)

    Lucon, E.; Scibetta, M.; McColskey, D.; McCowan, C.

    2009-01-15

    One of the key factors for obtaining reliable instrumented Charpy results is the calibration of the instrumented striker. The conventional approach for establishing an analytical relationship between strain gage output and force applied to the transducer is the static calibration, which is preferably performed with the striker installed in the pendulum assembly. However, the response of an instrumented striker under static force application may sometimes differ significantly from its dynamic performance during an actual Charpy test. This is typically reflected in a large difference between absorbed energy returned by the pendulum encoder (KV) and calculated under the instrumented force/displacement test record (Wt). Such difference can be either minimized by optimizing the striker design or analytically removed by adjusting forces and displacements until KV = Wt (the so-called 'Dynamic Force Adjustment'). This study investigates the influence of increasing force application rates on the force/voltage characteristics of two instrumented strikers, one at NIST in Boulder, CO and one at SCK-CEN in Mol, Belgium.

  16. Analysis of mechanical property data obtained from nuclear pressure vessel surveillance capsules

    International Nuclear Information System (INIS)

    Perrin, J.S.

    1977-01-01

    A typical pressure vessel surveillance capsule examination program provides mechanical property data from tensile, Charpy V-notch impact, and, in some cases, fracture mechanics specimens. This data must be analyzed in conjunction with the unirradiated baseline mechanical property data to determine the effect of irradiation on the mechanical properties. In the case of Charpy impact specimens, for example, irradiation typically causes an increase in the transition temperature, and a decrease in the upper shelf energy level. The results of the Charpy impact and other mechanical specimen tests must be evaluated to determine if property changes are occurring in the manner expected when the reactor was put into service. The large amount of data obtained from surveillance capsule examinations in recent years enables one to make fairly good predictions. After the changes in the mechanical properties of specimens from a particular surveillance capsule have been experimentally determined and evaluated, they must be related to the reactor pressure vessel. This requires a knowledge of the neutron fluence of the surveillance capsule, and the ratio of the surveillance capsule fluence to the pressure vessel wall fluence. This ratio is frequently specified by the reactor manufacturer, or can be calculated from a knowledge of the geometry and materials of the reactor components inside the pressure vessel. A knowledge of the exact neutron fluence of the capsule specimens and the capsule to vessel wall neutron fluence ratio is of great importance, since inaccuracies in these numbers cause just as serious a problem as inaccuracies in the mechanical property determinations. A further area causing analysis difficulties is problems encountered in recent capsule programs relating to capsule design, construction, operation, and dismantling. (author)

  17. Irradiation and annealing behavior of 15Kh2MFA reactor pressure vessel steel

    International Nuclear Information System (INIS)

    Popp, K.; Bergmann, U.; Bergner, F.; Hampe, E.; Leonhardt, W.D.; Schuetzler, H.P.; Viehrig, H.W.

    1992-01-01

    This work deals with the mechanical properties of RPV steels used WWER-440. The materials under investigation were a forging (base metal 15Kh2MFA) and the corresponding weld. Charpy V-notch specimens and tensile test specimens were irradiated in the WWER-2 Rheinsberg at about 270 C up to the two neutron fluence levels of 4 x 10 18 and 5 x 10 19 n/cm 2 (E>1MeV). Post-irradiation annealing heat treatments were performed, among others a 475 C/152 h treatment of technical interest. (orig.)

  18. Why does necking ignore notches in dynamic tension?

    Directory of Open Access Journals (Sweden)

    Rotbaum Y.

    2015-01-01

    Full Text Available Recent experimental work has revealed that necking of tensile specimens, subjected to dynamic loading, is a deterministic phenomenon, governed by the applied boundary conditions. Furthermore it was shown that the potential sited, dictated by the boundary conditions, may prevail even in the presence of a notch, thus necking may occur away of the notched region. The present paper combines experimental and numerical work to address this issue. Specifically, it is shown that the dynamic tensile failure locus is dictated by both the applied velocity boundary condition and the material mechanical properties, specifically strain-rate sensitivity and strain-rate hardening. It is shown that at sufficiently high impact velocities, the flows stress in the notch vicinity becomes quite higher than in the rest of the specimen, so that while the former resists deformation, it transfers the load to the latter, resulting in the formation of a local neck and failure away from the notch. Small local perturbations in the material properties are shown to be sufficient to stabilize the structure under local failure until a neck forms elsewhere. While the physical observations are quite counterintuitive with respect to the engineering views of stress concentrator's effect, the present work rationalizes those observations and also provides information for the designers of dynamically tensioned structures that may contain notches or similar flaws.

  19. Tensile and Charpy impact properties of an ODS ferritic/martensitic steel 9Cr–1.8W–0.5Ti–0.35Y{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guangming; Zhou, Zhangjian, E-mail: zhouzhj@mater.ustb.edu.cn; Wang, Man; Li, Shaofu; Zou, Lei; Zhang, Liwei

    2014-04-15

    Highlights: • The tensile property and Charpy impact were tested. • Both strength and plasticity in LT direction are better than that of TL direction. • The LSE was more than 65% of the USE from absorbed energy curve. • The initiation and propagation energy at different temperatures were calculated. • High LSE and dimples on the fracture surface indicated good toughness at −60 °C. - Abstract: A 9Cr-ODS ferritic/martensitic steel with a composition of 9Cr–1.8W–0.5Ti–0.35Y{sub 2}O{sub 3} was fabricated by mechanical alloying and hot isostatic pressing, followed by hot rolling. Tensile properties were measured at room temperature (23 °C) and 700 °C in the rolling direction (LT) and the transverse direction (TL). The ultimate tensile strength (UTS) of the as-rolled samples in both directions reached 990 MPa at 23 °C, and still maintained at 260 MPa at 700 °C. The tensile strength and elongation of the rolling direction was greater than that of the transverse direction. The Charpy impact was tested from −100 to 100 °C in the LT direction. The lower shelf energy (LSE) was more than 65% of the upper shelf energy (USE). The total absorbed energy was separated into the energies for crack initiation and propagation. The propagation energy was always higher than the initiation energy in the range of temperatures tested. The ductile-to-brittle transition temperature (DBTT) of the rolled 9Cr ODS evaluated by an absorbed energy curve was about 0 °C. However, the high LSE and the fracture surface that still contained dimples at lower shelf indicated good toughness of the as-rolled 9Cr ODS steels at temperature of −60 °C.

  20. Development of a reconstitution system of Charpy probes for the surveillance of vessels in nucleo electric plants

    International Nuclear Information System (INIS)

    Romero C, J.; Hernandez, R.; Fernandez, F.; Gonzalez M, A.

    2007-01-01

    This work describes the development of a welding system, for the rebuilding of halves of Charpy test tubes, the rebuilding consists on welding two implants in those ends of these halves of test tubes, in these welding the main requirement is not to alter the mechanical properties in a minimum volume of 1 cm 3 , the rebuilding is medullary in the surveillance programs of the reactor vessel. In these programs, the mechanical state of the vessel is evaluated, for it there are surveillance capsules with a Charpy witness test tubes series, subjected to a neutron flow similar or bigger to that of the vessel. The objective is to evaluate in advance on the vessel fragilization grade its life design. However the number of capsules with the witness test tubes it is only for the plant design life and at the moment the nucleo electric, negotiates an extension of life of these, until for 20 more years, of there the importance of this material witness's that stores the information of the damage accumulated by the neutron flow. This material requires to be taken advantage it after being rehearsed and the normative one settles down as obligatory to qualify the rebuilding process with all the requirements settled down in the ASTM Designation: E 1253-99 'Standard Guide for Reconstitution of irradiated Charpy-Sized Specimens', to obtain other reconstituted Charpy test tubes that are again introduced in the reactor. When being reconstituted the halves of the original test tubes it is obtained double reconstituted Charpy test tubes. Half of the test tubes they are used in the surveillance program of the vessel, with the surpluses test tubes, it can determine the fracture toughness, property of the material used in the extension methodology of life of vessel. (Author)

  1. Effect of rhenium and osmium on mechanical properties of a 9Cr-2W-0.25V-0.07Ta-0.1C steel

    International Nuclear Information System (INIS)

    Klueh, R.L.; Alexander, D.J.; Sokolov, M.A.

    2000-01-01

    The nuclear transmutation of tungsten to rhenium and osmium in a tungsten-containing steel irradiated in a fission or fusion reactor will change the chemical composition of the steel. To determine the possible consequences of such compositional changes on the mechanical properties, tensile and Charpy impact properties were measured on five 9Cr-2W-0.25V-0.07Ta-0.1C steels that contained different amounts of rhenium, osmium, and tungsten. The mechanical properties changes caused by these changes in composition were minor. Observations were also made on the effect of carbon concentration. The effect of carbon on tensile behavior was minor, but there was a large effect on Charpy properties. Several of the steels showed little effect of tempering temperature on the Charpy transition temperature, a behavior that was tentatively attributed to the low silicon and/or manganese concentration of the experimental steels

  2. Recent progress on gas tungsten arc welding of vanadium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Grossbeck, M.L.; King, J.F.; Alexander, D.J. [Oak Ridge National Lab., TN (United States)] [and others

    1997-08-01

    Emphasis has been placed on welding 6.4 mm plate, primarily by gas tungsten arc (GTA) welding. The weld properties were tested using blunt notch Charpy testing to determine the ductile to brittle transition temperature (DBTT). Erratic results were attributed to hydrogen and oxygen contamination of the welds. An improved gas clean-up system was installed on the welding glove box and the resulting high purity welds had Charpy impact properties similar to those of electron beam welds with similar grain size. A post-weld heat treatment (PWHT) of 950{degrees}C for two hours did not improve the properties of the weld in cases where low concentrations of impurities were attained. Further improvements in the gas clean-up system are needed to control hydrogen contamination.

  3. Clinical impact of de-regulated Notch-1 and Notch-3 in the development and progression of HPV-associated different histological subtypes of precancerous and cancerous lesions of human uterine cervix.

    Directory of Open Access Journals (Sweden)

    Richa Tripathi

    Full Text Available Cervical cancer is the leading cause of cancer related deaths among women in India. Limited reports are available for Notch-1 and Notch-3 protein in cervical carcinoma, which play crucial role in cell proliferation, differentiation, and apoptosis.This study was designed to evaluate the role of Notch-1 and Notch-3 with context to HPV infection in cervical carcinoma. A total of 168 tissue biopsy samples comprising of tumor specimens (n = 98, precancer (n = 30 and non-neoplastic cervical tissues (n = 40 were screened for HPV infection by PCR and expression of Notch-1 and Notch-3 protein by Immunohistochemistry and Immunoblotting.80% (24/30 were found to be positive for HPV in precancer and 86.7% (85/98 in cancer patients. Notch-1 expression of precancer and cancer cases was found to be significantly down-regulated with severity of disease in nuclear (3.43±0.29; 2.04±0.19, p = 0.0001, p = 0.0001 and cytoplasm (3.07±0.29; 2.29±0.17, p = 0.0001, p = 0.0001 obtained from different stages as compared to normal cervix tissue (5.40±0.19, 4.97±0.15; p<0.001; p<0.001. However, Notch-3 expression of above cases was significantly up-regulated with severity of disease and showed intense nuclear (4.17±0.39; 4.74±0.18, p = 0.0001, p = 0.0001 and cytoplasm (3.67±0.36; 4.48±0.18, p = 0.0001, p = 0.0001 of different stages as compared to normal cervix tissue (0.95±0.20, 0.70±0.20; p<0.001; p<0.001 respectively.These findings suggest that Notch-1 and Notch-3 may play an important role with synergistic effect of HPV in regulating development and proliferation of cervical cancer through the deregulation of Notch signalling. This study also shows the clinical utility of both proteins which may be used as predictable biomarkers in diagnosing different histological sub-types of HPV associated cervical cancer. Nevertheless, abnormal activation of this pathway may provide legitimate targets for cervical cancer therapy.

  4. Radiation embrittlement in pressure vessels of power reactors

    International Nuclear Information System (INIS)

    Kempf, Rodolfo; Fortis, Ana M.

    2007-01-01

    It is presented the project to study the effect of lead factors on the mechanical behavior of Reactor Pressure Vessel steels. It is described the facility designed to irradiate Charpy specimens with V notch of SA-508 type 3 steel at power reactor temperature, installed in the RA-1 reactor. The objective is to obtain the fracture behavior of irradiated specimens with different lead factors and to know their dependence with the diffusion of alloy elements. (author) [es

  5. Assessment of correlation between knee notch width index and the three-dimensional notch volume

    NARCIS (Netherlands)

    van Eck, C.F.; Martins, C.A.Q.; Lorenz, S.G.F.; Fu, F.H.; Smolinski, P.

    2010-01-01

    This study was done to determine whether there is a correlation between the notch volume and the notch width index (NWI) as measured on the three most frequently used radiographic views: the Holmblad 45A degrees, Holmblad 70A degrees, and Rosenberg view. The notch volume of 20 cadaveric knees was

  6. Coastal dune dynamics in response to excavated foredune notches

    Science.gov (United States)

    Ruessink, B. G.; Arens, S. M.; Kuipers, M.; Donker, J. J. A.

    2018-04-01

    Dune management along developed coasts has traditionally focussed on the suppression of the geomorphic dynamics of the foredune to improve its role in sea defence. Because a stabilized foredune acts as an almost total barrier to aeolian transport from the beach, the habitat diversity in the more landward dunes has degraded. With the overarching objective to mitigate this undesirable loss in biodiversity, dune management projects nowadays increasingly intend to restore aeolian dynamics by reconnecting the beach-dune system with notches excavated through the foredune. Here, we use repeat topographic survey data to examine the geomorphic response of a coastal dune system in the Dutch National Park Zuid-Kennemerland to five notches excavated in 2012-2013 within an 850-m stretch of the 20-m high established foredune. The notches were dug in a V-shape (viewed onshore), with a width between approximately 50 and 100 m at the top, a (cross-dune) length between 100 and 200 m, and excavation depths between 9 and 12.5 m. The 1 × 1 m digital terrain models, acquired with airborne Lidar and UAV photogrammetry, illustrate that during the 3-year survey period the notches developed into a U-shape because of wall deflation, and that up to 8-m thick and 150-m long depositional lobes formed landward of the notches. Sand budget computations showed that the sand volume of the entire study area increased by about 22,750 m3/year, which, given the 850-m width of the study area, corresponds to an aeolian input from the beach of approximately 26.5 m3/m/year. Between 2006 and 2012 all wind-blown beach sand deposited on the seaward side of the foredune; since 2013, the notches have caused 75% of the sand to be deposited landward of the foredune. This highlights that the notches are highly effective conduits for aeolian transport into the back dunes. Future monitoring is required to determine for how long the notches will stimulate aeolian dynamics and if (and when) vegetation eventually

  7. Quantification of the toughness distribution in a heavy section submerged arc multilayer reactor pressure vessel weldment

    International Nuclear Information System (INIS)

    Cerjak, H.; Prader, R.

    1999-01-01

    In a working procedure qualification test weld representing a heavy section circumferential reactor pressure vessel (RPV) weld tested in 1968, lower toughness values were observed in the top layer region compared to those found in the filler region. Gleeble simulation, extensive microscopic evaluation, diligent Charpy V-notch testing and modelling of the bead sequence and distribution of alloying elements was applied to explain this effect. It could be revealed that the microstructure of the weld metal is the most important factor influencing the toughness. When an 'as welded' microstructure is partly or fully reaustenitised by the adjacent multilayer beads, the microstructure transforms and the toughness increases. In the filler region, 85% of the cross-section consists from transformed microstructure, whereas in the top layer only 20% are transformed. It is quite evident that, accidentally, the notch tip of Charpy samples in 1968 were placed in untransformed microstructures. When the top layer on the inner surface of the RPV is weld cladded by austenitic stainless steel, full transformation occurs and the toughness representing the filler region can be taken into account for safety evaluations. (orig.)

  8. Experimental study on the resistance to hydrogen embrittlement of NIFS-V4Cr4Ti alloy

    International Nuclear Information System (INIS)

    Chen Jiming; Xu Zengyu; Den Ying; Muroga, T.

    2002-01-01

    SWIP (Southwestern Institute of Physics) has joined an international collaboration on the hydrogen embrittlement resistance evaluation of the vanadium alloy. This paper presents some experiments on the tensile properties and Charpy impact properties of the NIFS-V4Cr4Ti alloy with high-level hydrogen concentration. The experiment results show different properties against hydrogen embrittlement in static tension and impact load. The critical hydrogen concentration required to embrittle the alloy was about 215 - 310 mg·kg -1 on static tension load, but less than 130 mg·kg -1 on impact loading

  9. Re-utilization by '' Stud Welding'' of capsules charpy-V belonged to surveillance programs

    International Nuclear Information System (INIS)

    Lapena, J.; Perosanz, F. J.; Gachuz, M.

    1998-01-01

    The perspectives of nuclear plants life extension that are approximating to their end of design life compels to make new surveillance programs. The re-utilization of specimens belonging to surveillance capsules already tested in these new surveillance programs seems be a solution worldwide accepted. The two possible re-utilization processes of this irradiated material are: Subsized specimens and Reconstitution. While the first alternative (Subsized specimens) outlines serious problems for apply the results, the reconstitution eliminates this problem, since the resulting specimens after of the reconstruction procedure would be of the same dimensions that the original. The reconstruction process involves welds, and therefore it has associated the specific problems of this type of joints. Furthermore, by be tried to material irradiated with certain degree of internal damage, that is the variable to evaluate, requires that the heat contribution to the piece not originate local thermal treatments that alter its mechanical qualities. In this work has been followed the evolution by the variables of the weld process and their influence on the quality by the union from metallographic al point of view as well as mechanical for a weld procedure by Stud Welding. The principal objective is to optimize said parameters to assure a good mechanical continuity, without detriment of the microstructural characteristics of the original material. To verify this last have been accomplished with metallographical tests, temperature profile, hardness and will be carried out also Charpy tests. (Author)

  10. Notch sensitivity of aliphatic polyketone terpolymers

    NARCIS (Netherlands)

    Zuiderduin, W.C.J.; Huetink, Han; Gaymans, R.J.

    2004-01-01

    The notch sensitivity of aliphatic polyketone (PK) terpolymers was investigated in this article. The notch-tip radius was varied between the size of an actual propagating crack tip of 1-2 m and the largest notch tip of 1000 m radius. The larger notch-tip radii (1000-15 m) were milled into the

  11. Study of the ultrasonic technique of elapsed time of notch

    International Nuclear Information System (INIS)

    Gomes, L.C.F.L.; Rebello, J.M.A.

    1989-01-01

    The study of the ultrasonic technique of elapsed time in the dimensionment of notch inclined of 15 and 30 degree and of depth of 5 and 10 mm using the superficial Rayleigh wave and the mode conversion, with a headstock transmitter and other receiver. The dimensionment of notch and of the binding of the piece were made with headstock in different positions. Between the various results obtained can be mentioned the increase of the dimensionment, by two techniques, with the increase of the angle and/or of the depth. (V.R.B.)

  12. Comparisons of irradiation-induced shifts in fracture toughness, crack arrest toughness, and Charpy impact energy in high-copper welds

    International Nuclear Information System (INIS)

    Corwin, W.R.; Nanstad, R.K.; Iskander, S.K.

    1991-01-01

    The Heavy-Section Steel Irradiation (HSSI) Program is examining relative shifts and changes in shape of fracture and crack-arrest toughness versus temperature behavior for two high-copper welds. Fracture toughness 100-MPa√m temperature shifts are greater than Charpy 41-J shifts for both welds. Mean curve fits to the fracture toughness data provide mixed results regarding curve shape changes, but curves constructed as lower boundaries indicate lower slopes. Preliminary crack-arrest toughness results indicate that shifts of lower-bound curves are approximately the same as CVN 41-J shifts with no shape changes

  13. Clinical impact of de-regulated Notch-1 and Notch-3 in the development and progression of HPV-associated different histological subtypes of precancerous and cancerous lesions of human uterine cervix.

    Science.gov (United States)

    Tripathi, Richa; Rath, Gayatri; Jawanjal, Poonam; Sharma, Shweta; Singhal, Pallavi; Bhambhani, Suresh; Hussain, Showket; Bharadwaj, Mausumi

    2014-01-01

    Cervical cancer is the leading cause of cancer related deaths among women in India. Limited reports are available for Notch-1 and Notch-3 protein in cervical carcinoma, which play crucial role in cell proliferation, differentiation, and apoptosis. This study was designed to evaluate the role of Notch-1 and Notch-3 with context to HPV infection in cervical carcinoma. A total of 168 tissue biopsy samples comprising of tumor specimens (n = 98), precancer (n = 30) and non-neoplastic cervical tissues (n = 40) were screened for HPV infection by PCR and expression of Notch-1 and Notch-3 protein by Immunohistochemistry and Immunoblotting. 80% (24/30) were found to be positive for HPV in precancer and 86.7% (85/98) in cancer patients. Notch-1 expression of precancer and cancer cases was found to be significantly down-regulated with severity of disease in nuclear (3.43±0.29; 2.04±0.19, p = 0.0001, p = 0.0001) and cytoplasm (3.07±0.29; 2.29±0.17, p = 0.0001, p = 0.0001) obtained from different stages as compared to normal cervix tissue (5.40±0.19, 4.97±0.15; pcervix tissue (0.95±0.20, 0.70±0.20; pcancer through the deregulation of Notch signalling. This study also shows the clinical utility of both proteins which may be used as predictable biomarkers in diagnosing different histological sub-types of HPV associated cervical cancer. Nevertheless, abnormal activation of this pathway may provide legitimate targets for cervical cancer therapy.

  14. Tyrosine phosphorylation and proteolytic cleavage of Notch are required for non-canonical Notch/Abl signaling in Drosophila axon guidance.

    Science.gov (United States)

    Kannan, Ramakrishnan; Cox, Eric; Wang, Lei; Kuzina, Irina; Gu, Qun; Giniger, Edward

    2018-01-17

    Notch signaling is required for the development and physiology of nearly every tissue in metazoans. Much of Notch signaling is mediated by transcriptional regulation of downstream target genes, but Notch controls axon patterning in Drosophila by local modulation of Abl tyrosine kinase signaling, via direct interactions with the Abl co-factors Disabled and Trio. Here, we show that Notch-Abl axonal signaling requires both of the proteolytic cleavage events that initiate canonical Notch signaling. We further show that some Notch protein is tyrosine phosphorylated in Drosophila , that this form of the protein is selectively associated with Disabled and Trio, and that relevant tyrosines are essential for Notch-dependent axon patterning but not for canonical Notch-dependent regulation of cell fate. Based on these data, we propose a model for the molecular mechanism by which Notch controls Abl signaling in Drosophila axons. © 2018. Published by The Company of Biologists Ltd.

  15. Band-notched spiral antenna

    Science.gov (United States)

    Jeon, Jae; Chang, John

    2018-03-13

    A band-notched spiral antenna having one or more spiral arms extending from a radially inner end to a radially outer end for transmitting or receiving electromagnetic radiation over a frequency range, and one or more resonance structures positioned adjacent one or more segments of the spiral arm associated with a notch frequency band or bands of the frequency range so as to resonate and suppress the transmission or reception of electromagnetic radiation over said notch frequency band or bands.

  16. Visual interface for the automation of the instrumented pendulum of Charpy tests used in the surveillance program of reactors vessel of nuclear power plants

    International Nuclear Information System (INIS)

    Rojas S, A.S.; Sainz M, E.; Ruiz E, J.A.

    2004-01-01

    Inside the Programs of Surveillance of the nuclear power stations periodic information is required on the state that keep the materials with those that builds the vessel of the reactor. This information is obtained through some samples or test tubes that are introduced inside the core of the reactor and it is observed if its physical characteristics remain after having been subjected to the radiation changes and temperature. The rehearsal with the instrumented Charpy pendulum offers information on the behavior of fracture dynamics of a material. In the National Institute of Nuclear Research (ININ) it has an instrumented Charpy pendulum. The operation of this instrument is manual, having inconveniences to carry out rehearsals with radioactive material, handling of high and low temperatures, to fulfill the normative ones for the realization of the rehearsals, etc. In this work the development of a computational program is presented (virtual instrument), for the automation of the instrumented pendulum. The system has modules like: Card of data acquisition, signal processing, positioning system, tempered system, pneumatic system, compute programs like it is the visual interface for the operation of the instrumented Charpy pendulum and the acquisition of impact signals. This system shows that given the characteristics of the nuclear industry with radioactive environments, the virtual instrumentation and the automation of processes can contribute to diminish the risks to the personnel occupationally exposed. (Author)

  17. Ultra low carbon bainitic (ULCB) steels after quenching and tempering

    International Nuclear Information System (INIS)

    Lis, A.K.; Lis, J.; Kolan, C.; Jeziorski, L.

    1998-01-01

    The mechanical and Charpy V impact strength properties of new advanced ultra low carbon bainitic (ULBC) steels after water quenching and tempering (WQT) have been investigated. Their chemical compositions are given. The nine continuous cooling transformation diagrams (CCT) of the new ULCB steel grades have been established. The CCT diagrams for ULCB N i steels containing 9% Ni - grade 10N9 and 5% Ni - grade HN5MVNb are given. The comparison between CCT diagrams of 3.5%Ni + 1.5%Cu containing steels grade HSLA 100 and HN3MCu is shown. The effect of the increase in carbon and titanium contents in the chemical composition of ULCB M n steels 04G3Ti, 06G3Ti and 09G3Ti on the kinetics of phase transformations during continuous cooling is presented by the shifting CCT diagrams. The Charpy V impact strength and brittle fracture occurence curves are shown. The effect of tempering temperature on tensile properties of WQT HN3MCu steel is shown and Charpy V impact strength curves after different tempering conditions are shown. The optimum tempering temperatures region of HN3MCu steel for high Charpy V impact toughness at law temperatures - 80 o C(193 K) and -120 o C(153 K) is estimated. The effect of tempering temperature on mechanical properties of HN5MVNb steel is given. The low temperature impact Charpy V toughness of HN5MVNb steel is shown. The optimum range of tempering temperature during 1 hour for high toughness of WQT HN5MVNb steel is given. HN3MCu and HN5MVNb steels after WQT have high yield strength YS≥690 MPa and high Charpy V impact toughness KV≥80 J at -100 o C (173K) and KCV≥50 J/cm 2 at - 120 o C (153K) so they may be used for cryogenic applications

  18. Characterization of metallurgical and mechanical properties on the multi-pass welding of Inconel 625 and AISI 316L

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, K. Gokul; Ramkumar, K. Devendranath; Arivazhagan, N. [VIT University, Vellore (India)

    2015-03-15

    This article investigated the weldability, metallurgical and mechanical properties of Inconel 625 and AISI 316L stainless steel weldments obtained by continuous current (CC) and pulsed current (PC) gas tungsten arc welding (GTAW) processes employing ERNiCr-3 and ER2209 fillers. Microstructure studies showed the migrated grain boundaries at the weld zone of ERNiCr-3 weldments and multidirectional grain growth for ER2209 weldments. It was inferred from the tension tests that the fracture occurred at the parent metal of AISI 316L in all the cases. Charpy V-notch impact tests accentuated that the CCGTA weldments employing ERNiCr-3 filler offered better impact toughness of 77 J at room temperature. Further a detailed study has been carried out to analyze the structure - property relationships of these weldments using the combined techniques of scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis.

  19. Evaluations of the criterion for lateral expansion of steels for nuclear components

    International Nuclear Information System (INIS)

    Susukida, H.; Satoh, M.; Fukuhara, A.

    1980-01-01

    The Charpy V notch impact tests were performed on Japanese made ferritic steels for nuclear components and their lateral expansions were investigated. The correlations of lateral expansion and absorbed energy with yield strength, and the correlation between lateral expansion and fracture toughness were also studied. The correlation at each lateral expansion level between absorbed energy and yield strength almost agreed with that published by the US PVRC. It was confirmed that lateral expansion could be used as a criterion for the toughness of the steels corresponding to changes in their yield strength, and that the lateral expansion criterion adopted in the ASME Code Section III was appropriate. Further, the correlation between fracture toughness and lateral expansion and that between fracture toughness and absorbed energy, were evaluated, and respective equations of correlation were proposed. (author)

  20. Charpy impact test results of ferritic alloys from the HFIR[High Flux Isotope Reactor]-MFE-RB2 test

    International Nuclear Information System (INIS)

    Hu, W.L.; Gelles, D.S.

    1987-03-01

    Miniature Charpy specimens of HT-9 in base metal, weld metal and heat affected zone (HAZ) metal conditions, and 9Cr-1Mo in base metal and weld metal conditions have been tested following irradiation in HFIR-MFE-RB2 at 55 0 C to ≅10 dpa. All specimen conditions have degraded properties (both DBTT and USE) in comparison with specimens irradiated to lower dose. 9Cr-Mo degraded more than HT-9 and weld metal performed worse than base metal which performed worse than HAZ material. Property degradation was approximately linear as a function of dose, indicating that degradation response had not saturated by 10 dpa

  1. Neutron embrittlement of the reactor vessel in Borssele as determined from Charpy specimens

    International Nuclear Information System (INIS)

    Oosterkamp, W.J.; Dufour, L.B.

    1983-01-01

    Two sets of Charpy specimens have been retrieved from the reactor in the nuclear power plant at Borssele after two and four cycles of operation, respectively. The neutron fluxes at the sample positions and at the vessel wall have been calculated with a point-kernel method and S 2 calculations. The calculated fluxes at the two specimen positions are in fair agreement with fluences measured by threshold detectors. The Reference Temperature of Nil Ductility has been determined from the Charpy tests by a tan-h fit procedure. An extrapolation to a 40-year vessel life has been made on the basis of a square-root dependence of the change in the reference temperature with effective full-power years. Under these assumptions the heat-affected zone material will reach 296 K. The other materials will remain below 280 K. The vessel life therefore is not limited by embrittlement. (orig.)

  2. Abaca fibre reinforced PP composites and comparison with jute and flax fibre PP composites

    Directory of Open Access Journals (Sweden)

    2007-11-01

    Full Text Available Abaca fibre reinforced PP composites were fabricated with different fibre loadings (20, 30, 40, 50wt% and in some cases 35 and 45 wt%. Flax and jute fibre reinforced PP composites were also fabricated with 30 wt% fibre loading. The mechanical properties, odour emission and structure properties were investigated for those composites. Tensile, flexural and Charpy impact strengths were found to increase for fibre loadings up to 40 wt% and then decreased. Falling weight impact tests were also carried out and the same tendency was observed. Owing to the addition of coupling agent (maleated polypropylene -MAH-PP, the tensile, flexural and falling weight impact properties were found to increase in between 30 to 80% for different fibre loadings. When comparing jute and flax fibre composites with abaca fibre composites, jute fibre composites provided best tensile properties but abaca fibre polypropylene composites were shown to provide best notch Charpy and falling weight impact properties. Odours released by flax fibre composites were smaller than jute and abaca fibre composites.

  3. Notch Inhibits Osteoblast Differentiation and Causes Osteopenia

    Science.gov (United States)

    Zanotti, Stefano; Smerdel-Ramoya, Anna; Stadmeyer, Lisa; Durant, Deena; Radtke, Freddy; Canalis, Ernesto

    2008-01-01

    Notch receptors are determinants of cell fate decisions. To define the role of Notch in the adult skeleton, we created transgenic mice overexpressing the Notch intracellular domain (NICD) under the control of the type I collagen promoter. First-generation transgenics were small and osteopenic. Bone histomorphometry revealed that NICD caused a decrease in bone volume, secondary to a reduction in trabecular number; osteoblast and osteoclast number were decreased. Low fertility of founder mice and lethality of young pups did not allow the complete establishment of transgenic lines. To characterize the effect of Notch overexpression in vitro, NICD was induced in osteoblasts and stromal cells from Rosanotch mice, in which a STOP cassette flanked by loxP sites is upstream of NICD, by transduction with an adenoviral vector expressing Cre recombinase (Cre) under the control of the cytomegalovirus (CMV) promoter (Ad-CMV-Cre). NICD impaired osteoblastogenesis and inhibited Wnt/β-catenin signaling. To determine the effects of notch1 deletion in vivo, mice in which notch1 was flanked by loxP sequences (notch1loxP/loxP) were mated with mice expressing Cre recombinase under the control of the osteocalcin promoter. Conditional null notch1 mice had no obvious skeletal phenotype, possibly because of rescue by notch2; however, 1-month-old females exhibited a modest increase in osteoclast surface and eroded surface. Osteoblasts from notch1loxP/loxP mice, transduced with Ad-CMV-Cre and transfected with Notch2 small interfering RNA, displayed increased alkaline phosphatase activity. In conclusion, Notch signaling in osteoblasts causes osteopenia and impairs osteo-blastogenesis by inhibiting the Wnt/β-catenin pathway. PMID:18420737

  4. Notch-strengthening in two-dimensional foams

    NARCIS (Netherlands)

    Onck, P.R.

    Metallic foams show notch-strengthening behavior when analyzing double-edge notched specimen in compression and tension. A discrete microstructural model has been used to simulate the effect of notch depth and specimen size on the net-section-strength. The non-uniform deformation behavior is

  5. A Novel Notch-YAP Circuit Drives Stemness and Tumorigenesis in Embryonal Rhabdomyosarcoma.

    Science.gov (United States)

    Slemmons, Katherine K; Crose, Lisa E S; Riedel, Stefan; Sushnitha, Manuela; Belyea, Brian; Linardic, Corinne M

    2017-12-01

    Rhabdomyosarcoma (RMS), a cancer characterized by skeletal muscle features, is the most common soft-tissue sarcoma of childhood. While low- and intermediate-risk groups have seen improved outcomes, high-risk patients still face a 5-year survival rate of statistic that has not changed in over 40 years. Understanding the biologic underpinnings of RMS is critical. The developmental pathways of Notch and YAP have been identified as potent but independent oncogenic signals that support the embryonal variant of RMS (eRMS). Here, the cross-talk between these pathways and the impact on eRMS tumorigenesis is reported. Using human eRMS cells grown as three-dimensional (3D) rhabdospheres, which enriches in stem cells, it was found that Notch signaling transcriptionally upregulates YAP1 gene expression and YAP activity. Reciprocally, YAP transcriptionally upregulates the Notch ligand genes JAG1 and DLL1 and the core Notch transcription factor RBPJ This bidirectional circuit boosts expression of key stem cell genes, including SOX2 , which is functionally required for eRMS spheres. Silencing this circuit for therapeutic purposes may be challenging, because the inhibition of one node (e.g., pharmacologic Notch blockade) can be rescued by upregulation of another (constitutive YAP expression). Instead, dual inhibition of Notch and YAP is necessary. Finally, supporting the existence of this circuit beyond a model system, nuclear Notch and YAP protein expression are correlated in human eRMS tumors, and YAP suppression in vivo decreases Notch signaling and SOX2 expression. Implications: This study identifies a novel oncogenic signaling circuit driving eRMS stemness and tumorigenesis, and provides evidence and rationale for combination therapies co-targeting Notch and YAP. Mol Cancer Res; 15(12); 1777-91. ©2017 AACR . ©2017 American Association for Cancer Research.

  6. PKCζ regulates Notch receptor routing and activity in a Notch signaling-dependent manner

    NARCIS (Netherlands)

    Sjöqvist, M.; Antfolk, D.; Ferraris, S.; Rraklli, V.; Haga, C.; Antila, C.; Mutvei, A.; Imanishi, S.Y.; Holmberg, J.; Jin, S.; Eriksson, J.E.; Lendahl, U.; Sahlgren, C.M.

    Activation of Notch signaling requires intracellular routing of the receptor, but the mechanisms controlling the distinct steps in the routing process is poorly understood. We identify PKCζ as a key regulator of Notch receptor intracellular routing. When PKCζ was inhibited in the developing chick

  7. Notch filters for port-Hamiltonian systems

    NARCIS (Netherlands)

    Dirksz, D.A.; Scherpen, J.M.A.; van der Schaft, A.J.; Steinbuch, M.

    2012-01-01

    In this paper a standard notch filter is modeled in the port-Hamiltonian framework. By having such a port-Hamiltonian description it is proven that the notch filter is a passive system. The notch filter can then be interconnected with another (nonlinear) port-Hamiltonian system, while preserving the

  8. Heterogeneity of breast cancer stem cells as evidenced with Notch-dependent and Notch-independent populations

    International Nuclear Information System (INIS)

    Wong, Nelson K Y; Fuller, Megan; Sung, Sandy; Wong, Fred; Karsan, Aly

    2012-01-01

    Studies have suggested the potential importance of Notch signaling to the cancer stem cell population in some tumors, but it is not known whether all cells in the cancer stem cell fraction require Notch activity. To address this issue, we blocked Notch activity in MCF-7 cells by expressing a dominant-negative MAML-GFP (dnMAML) construct, which inhibits signaling through all Notch receptors, and quantified the effect on tumor-initiating activity. Inhibition of Notch signaling reduced primary tumor sphere formation and side population. Functional quantification of tumor-initiating cell numbers in vivo showed a significant decrease, but not a complete abrogation, of these cells in dnMAML-expressing cells. Interestingly, when assessed in secondary assays in vitro or in vivo, there was no difference in tumor-initiating activity between the dnMAML-expressing cells and control cells. The fact that a subpopulation of dnMAML-expressing cells was capable of forming primary and secondary tumors indicates that there are Notch-independent tumor-initiating cells in the breast cancer cell line MCF-7. Our findings thus provide direct evidence for a heterogeneous cancer stem cell pool, which will require combination therapies against multiple oncogenic pathways to eliminate the tumor-initiating cell population

  9. Instrumentation of a Charpy-pendulum. Additional data obtained from it and its application to nuclear reactor pressure vessels surveillance programs; Instrumentacion de un pendulo Charpy. Datos adicionales obtenidos a partir de la misma y su aplicacion a programas de vigilancia de centrales nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Chomik, Enrique P; Dhers, Horacio; Iorio, Antonio F [Comision Nacional de Energia Atomica, General San Martin (Argentina). Dept. de Materiales; Ciriani, Dario F [Comision Nacional de Energia Atomica, General San Martin (Argentina). Dept. de Combustibles Nucleares

    1999-07-01

    Charpy test gives information about a material dynamic fracture behavior. In a plain Charpy test, this information is the absorbed energy during fracture of the specimen, lateral deformation and the percentage of ductile fracture of the specimen. These parameters can then be used for the determination of the material response to a dynamic applied load, and are used at present to determine the brittle-ductile transition temperature of a material. However, there is a lot of additional information that can be obtained from a Charpy test, which is vital for the case of surveillance programs of nuclear power plants, where it is necessary to get the most available information from the specimens to be tested, because each one of them was irradiated for many years under temperature and neutronic flux conditions similar to that of the internal surface of the reactor pressure vessel, which converts these specimens in unique and very expensive ones. This additional information can be obtained from the curve that determines the evolution of the applied force to the specimen throughout the time involved in its fracture. It was possible to instrument a Charpy pendulum at a fraction of the cost necessary to buy an instrumentation package like the ones available in the market, and since the instrumentation equipment obtained is easy to transport. It has the additional advantage that can be used to instrument any other pendulum replacing only the hammer of the pendulum with a instrumented one for that pendulum. (author)

  10. Eddy current standards - Cracks versus notches

    Science.gov (United States)

    Hagemaier, D. J.; Collingwood, M. R.; Nguyen, K. H.

    1992-10-01

    Eddy current tests aimed at evaluating cracks and electron-discharge machined (EDM) notches in 7075-T6 aluminum specimens are described. A comparison of the shape and amplitude of recordings made from both transverse and longitudinal scans of small EDM notches and fatigue cracks showd almost identical results. The signal amplitude and phase angle increased with an increase of EDM notch and crak size. It is concluded that equivalent eddy current results obtained from similar-size surface cracks and notches in aluminum can be used to establish a desired sensitivity level for inspection.

  11. Effects of irradiation on crack-arrest toughness of two high-copper welds

    International Nuclear Information System (INIS)

    Iskander, S.K.; Corwin, W.R.; Nanstad, R.K.

    1990-01-01

    The objective of this study is to determine the effect of neutron irradiation on the shift and shape of the lower-bound curve to crack-arrest data. Two submerged-arc welds with copper contents of 0.23 and 0.31 wt % were commercially fabricated in 220-mm-thick plate. Crack-arrest specimens fabricated from these welds were irradiated at a nominal temperature of 288 degree C to an average fluence of 1.9 x 10 19 neutrons/cm 2 (>1 MeV). A preliminary evaluation of the results shows that the neutron-irradiation induced crack-arrest toughness temperature shift is about the same as the Charpy V-notch impact temperature shift at the 41-J energy level. The shape of the lower-bound curves, (for the range of test temperatures covered), compared to those of the ASME K Ia -curve did not seem to have been altered by irradiation. 10 refs., 9 figs., 7 tabs

  12. Results of crack-arrest tests on two irradiated high-copper welds

    International Nuclear Information System (INIS)

    Iskander, S.K.; Corwin, W.R.; Nanstead, R.K.

    1990-12-01

    The objective of this study was to determine the effect of neutron irradiation on the shift and shape of the lower-bound curve to crack-arrest data. Two submerged-arc welds with copper contents of 0.23 and 0.31 wt % were commercially fabricated in 220-mm-thick plate. Crack-arrest specimens fabricated from these welds were irradiated at a nominal temperature of 288 degree C to an average fluence of 1.9 x 10 19 neutrons/cm 2 (>1 MeV). Evaluation of the results shows that the neutron-irradiation-induced crack-arrest toughness temperature shift is about the same as the Charpy V-notch impact temperature shift at the 41-J energy level. The shape of the lower-bound curves (for the range of test temperatures covered) did not seem to have been altered by irradiation compared to those of the ASME K Ia curve. 9 refs., 21 figs., 10 tabs

  13. Characterization of activating mutations of NOTCH3 in T-cell acute lymphoblastic leukemia and anti-leukemic activity of NOTCH3 inhibitory antibodies.

    Science.gov (United States)

    Bernasconi-Elias, P; Hu, T; Jenkins, D; Firestone, B; Gans, S; Kurth, E; Capodieci, P; Deplazes-Lauber, J; Petropoulos, K; Thiel, P; Ponsel, D; Hee Choi, S; LeMotte, P; London, A; Goetcshkes, M; Nolin, E; Jones, M D; Slocum, K; Kluk, M J; Weinstock, D M; Christodoulou, A; Weinberg, O; Jaehrling, J; Ettenberg, S A; Buckler, A; Blacklow, S C; Aster, J C; Fryer, C J

    2016-11-24

    Notch receptors have been implicated as oncogenic drivers in several cancers, the most notable example being NOTCH1 in T-cell acute lymphoblastic leukemia (T-ALL). To characterize the role of activated NOTCH3 in cancer, we generated an antibody that detects the neo-epitope created upon gamma-secretase cleavage of NOTCH3 to release its intracellular domain (ICD3), and sequenced the negative regulatory region (NRR) and PEST (proline, glutamate, serine, threonine) domain coding regions of NOTCH3 in a panel of cell lines. We also characterize NOTCH3 tumor-associated mutations that result in activation of signaling and report new inhibitory antibodies. We determined the structural basis for receptor inhibition by obtaining the first co-crystal structure of a NOTCH3 antibody with the NRR protein and defined two distinct epitopes for NRR antibodies. The antibodies exhibit potent anti-leukemic activity in cell lines and tumor xenografts harboring NOTCH3 activating mutations. Screening of primary T-ALL samples reveals that 2 of 40 tumors examined show active NOTCH3 signaling. We also identified evidence of NOTCH3 activation in 12 of 24 patient-derived orthotopic xenograft models, 2 of which exhibit activation of NOTCH3 without activation of NOTCH1. Our studies provide additional insights into NOTCH3 activation and offer a path forward for identification of cancers that are likely to respond to therapy with NOTCH3 selective inhibitory antibodies.

  14. Effects of Thermal Aging on Microstructure and Impact Properties of 316LN Stainless Steel Weld

    Directory of Open Access Journals (Sweden)

    LUO Qiang

    2017-12-01

    Full Text Available To study the thermal aging of nuclear primary pipe material 316LN stainless steel weld, accelerated thermal aging experiment was performed at 400℃ for 15000h. Microstructure evolution of weld after aging was investigated by TEM and HREM. Impact properties of weld thermally aged at different time was measured by Charpy impact test. Meanwhile, taking Charpy impact energy as the standard of thermal aging embrittlement, the thermal kinetics formula was obtained by the fitting method. Finally, the Charpy impact properties of the weld during 60 years of service at the actual operation temperature were estimated by the thermal kinetics formula. The results indicate that the spinodal decomposition occurs in the ferrite of the weld after thermal aging at 400℃ for 1000h, results in α (Fe-rich and α'(Cr-rich phases, and meanwhile, the G-phase is precipitated in the ferrite; the spinodal decomposition and the G-phase precipitation lead to the decrease in the impact energy of weld as time prolongs; the prediction results show that the Charpy impact energy of weld decreases quickly in the early 25 years, and then undergoes a slow decrease during the subsequent operation process.

  15. Charpy impact test results of ferritic alloys at a fluence of 6 x 1022n/cm2

    International Nuclear Information System (INIS)

    Hu, W.L.

    1985-01-01

    Charpy impact tests on specimens in the AD-2 reconstitution experiment were completed. One hundred ten specimens made of HT-9 base metal, 9Cr-1Mo base metal and 9Cr-1Mo weldment at various heat treatment conditions were tested in temperature range from -73 0 C to 260 0 C. The specimens were irradiated from 390 0 C to 550 0 C and the fluence of the specimens reached 6 x 10 22 n/cm 2 . This is the first time that the transition behavior of ferritic alloys at high fluence was obtained. This is also the first time that comprehensive results on the irradiated 9Cr-1Mo weldment are available. The test results show a small additional shift in transition temperature for HT-9 base metal irradiated at 390 0 C and 450 0 C as the fluence was raised to 6 x 10 22 n/cm 2 . At higher irradiation temperatures, however, the shift in transition temperature is less conclusive. Further reduction in USE was observed at higher fluence for all the irradiation temperatures. There is no apparent fluence effect for 9Cr-1Mo base metal at all the irradiation temperatures studied. Contrary to the previous finding on HT-9 base metal and weldment, the 9Cr-1Mo weldment shows a higher transition temperature ( + 60 0 C) and a higher USE ( + 100%) as compared to the 9Cr-1MO base metal for the same irradiation conditions. 6 references, 7 figures, 7 tables

  16. DOL behaviour of end-notched beams

    DEFF Research Database (Denmark)

    Gustafsson, P.J.; Hoffmeyer, Preben; Valentin, G.

    1998-01-01

    The long-term loading strength of end-notched beams made of glulam and LVL was tested. The beams were of various sizes, with and without a moisture sealing at the notch. Tests were conducted in open shelter climates, and at constant and cyclic relative humidity. The short-term strength was tested...... beams with a moisture sealing at the notch...

  17. The Effect of Constant and Pulsed Current Gas Tungsten Arc Welding on Joint Properties of 2205 Duplex Stainless Steel to 316L Austenitic Stainless Steel

    Science.gov (United States)

    Neissi, R.; Shamanian, M.; Hajihashemi, M.

    2016-05-01

    In this study, dissimilar 316L austenitic stainless steel/2205 duplex stainless steel (DSS) joints were fabricated by constant and pulsed current gas tungsten arc welding process using ER2209 DSS as a filler metal. Microstructures and joint properties were characterized using optical and electron scanning microscopy, tensile, Charpy V-notch impact and micro-hardness tests, and cyclic polarization measurements. Microstructural observations confirmed the presence of chromium nitride and delta ferrite in the heat-affected zone of DSS and 316L, respectively. In addition, there was some deviation in the austenite/ferrite ratio of the surface welding pass in comparison to the root welding pass. Besides having lower pitting potential, welded joints produced by constant current gas tungsten arc welding process, consisted of some brittle sigma phase precipitates, which resulted in some impact energy reduction. The tensile tests showed high tensile strength for the weld joints in which all the specimens were broken in 316L base metal.

  18. Properties of Free-Machining Aluminum Alloys at Elevated Temperatures

    Science.gov (United States)

    Faltus, Jiří; Karlík, Miroslav; Haušild, Petr

    In areas close to the cutting tool the workpieces being dry machined could be heated up to 350°C and they may be impact loaded. Therefore it is of interest to study mechanical properties of corresponding materials at elevated temperatures. Free-machining alloys of Al-Cu and Al-Mg-Si systems containing Pb, Bi and Sn additions (AA2011, AA2111B, AA6262, and AA6023) were subjected to Charpy U notch impact test at the temperatures ranging from 20 to 350°C. The tested alloys show a sharp drop in notch impact strength KU at different temperatures. This drop of KU is caused by liquid metal embrittlement due to the melting of low-melting point dispersed phases which is documented by differential scanning calorimetry. Fracture surfaces of the specimens were observed using a scanning electron microscope. At room temperature, the fractures of all studied alloys exhibited similar ductile dimple fracture micromorphology, at elevated temperatures, numerous secondary intergranular cracks were observed.

  19. In-place thermal annealing of nuclear reactor pressure vessels

    International Nuclear Information System (INIS)

    Server, W.L.

    1985-04-01

    Radiation embrittlement of ferritic pressure vessel steels increases the ductile-brittle transition temperature and decreases the upper shelf level of toughness as measured by Charpy impact tests. A thermal anneal cycle well above the normal operating temperature of the vessel can restore most of the original Charpy V-notch energy properties. The Amry SM-1A test reactor vessel was wet annealed in 1967 at less than 343 0 C (650 0 F), and wet annealing of the Belgian BR-3 reactor vessel at 343 0 C (650 0 F) has recently taken place. An industry survey indicates that dry annealing a reactor vessel in-place at temperatures as high as 454 0 C (850 0 F) is feasible, but solvable engineering problems do exist. Economic considerations have not been totally evaluated in assessing the cost-effectiveness of in-place annealing of commercial nuclear vessels. An American Society for Testing and Materials (ASTM) task group is upgrading and revising guide ASTM E 509-74 with emphasis on the materials and surveillance aspects of annealing rather than system engineering problems. System safety issues are the province of organizations other than ASTM (e.g., the American Society of Mechanical Engineers Boiler and Pressure Vessel Code body)

  20. Belgian Contribution to the IAEA CRP-IV Programme on Assuring Structural Integrity of Reactor Pressure Vessel

    International Nuclear Information System (INIS)

    Van Walle, E.; Chaouadi, R.; Scibetta, M.; Puzzolante, J.L.; Fabry, A.; Van de Velde, J.

    1997-10-01

    This report contains the actual status of the Belgian contribution to the IAEA CRP-IV program. Besides Charpy-V impact tests on as-received CRP-IV JRQ-specimens, fracture toughness tests were performed on two geometries: PCCV-specimens and CRB-specimens. The Charpy-V impact results correspond very well with the as-received CRP-III results. The fracture toughness data are also very consistent with identical tests recently performed on remaining as-received CRP-III material. Irradiated broken Charpy-V samples were reconstituted and tested in PCCV-mode. This was done in order to investigate the evolution of the ASME-curve versus the evolution of the mastercurve with irradiation. Initial results were reported. A new CHIVAS-irradiation in the CALLISTO-loop of the BR-2-reactor to support this investigation, is under preparation

  1. Standard Guide for In-Service Annealing of Light-Water Moderated Nuclear Reactor Vessels

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2003-01-01

    1.1 This guide covers the general procedures to be considered for conducting an in-service thermal anneal of a light-water moderated nuclear reactor vessel and demonstrating the effectiveness of the procedure. The purpose of this in-service annealing (heat treatment) is to improve the mechanical properties, especially fracture toughness, of the reactor vessel materials previously degraded by neutron embrittlement. The improvement in mechanical properties generally is assessed using Charpy V-notch impact test results, or alternatively, fracture toughness test results or inferred toughness property changes from tensile, hardness, indentation, or other miniature specimen testing (1). 1.2 This guide is designed to accommodate the variable response of reactor-vessel materials in post-irradiation annealing at various temperatures and different time periods. Certain inherent limiting factors must be considered in developing an annealing procedure. These factors include system-design limitations; physical constrain...

  2. Plastic fracture toughness of austenitic welding connection for Ver-1000 nuclear reactor piping of 300-350 mm diameter

    International Nuclear Information System (INIS)

    Vasil'chenko, G.S.; Dragunov, Yu.G.; Kabelevskij, M.G.; Kazantsev, A.G.; Kunavin, S.A.; Merinov, G.N.; Sokov, L.M.

    2000-01-01

    The outside welding technology for circular welds in a pearlitic tube using austenitic welding wire materials is developed and applied in manufacturing pipelines of CPP and ECC. Mechanical properties and fracture toughness of austenitic welded joints in pearlitic tubes are determined to substantiate by calculation the practicality of the leakage prior to failure concept. The work is accomplished on experimental tube manufactured by hand arc welding. When manufactured the tube is cut into 5 rings. From the rings the tensile specimens are cut for testing at 20 and 350 deg C as well as Charpy V-notch impact specimens and compact specimens ST-1T. It is shown that the materials of the experimental tube meet the standard requirements. Only axial specimens cut across the weld are not in conformity with the requirements for specific elongation [ru

  3. Biochemical characterization and cellular effects of CADASIL mutants of NOTCH3.

    Directory of Open Access Journals (Sweden)

    He Meng

    Full Text Available Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL is the best understood cause of dominantly inherited stroke and results from NOTCH3 mutations that lead to NOTCH3 protein accumulation and selective arterial smooth muscle degeneration. Previous studies show that NOTCH3 protein forms multimers. Here, we investigate protein interactions between NOTCH3 and other vascular Notch isoforms and characterize the effects of elevated NOTCH3 on smooth muscle gene regulation. We demonstrate that NOTCH3 forms heterodimers with NOTCH1, NOTCH3, and NOTCH4. R90C and C49Y mutant NOTCH3 form complexes which are more resistant to detergents than wild type NOTCH3 complexes. Using quantitative NOTCH3-luciferase clearance assays, we found significant inhibition of mutant NOTCH3 clearance. In coculture assays of NOTCH function, overexpressed wild type and mutant NOTCH3 significantly repressed NOTCH-regulated smooth muscle transcripts and potently impaired the activity of three independent smooth muscle promoters. Wildtype and R90C recombinant NOTCH3 proteins applied to cell cultures also blocked canonical Notch fuction. We conclude that CADASIL mutants of NOTCH3 complex with NOTCH1, 3, and 4, slow NOTCH3 clearance, and that overexpressed wild type and mutant NOTCH3 protein interfere with key NOTCH-mediated functions in smooth muscle cells.

  4. Analysis list: NOTCH1 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available NOTCH1 Blood + hg19 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/NOTCH1.1....tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/NOTCH1.5.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/NOTC...H1.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/NOTCH1.Blood.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/Blood.gml ...

  5. Developmental exposure to 2,3,7,8 tetrachlorodibenzo-p-dioxin attenuates later-life Notch1-mediated T cell development and leukemogenesis

    International Nuclear Information System (INIS)

    Ahrenhoerster, Lori S.; Leuthner, Tess C.; Tate, Everett R.; Lakatos, Peter A.; Laiosa, Michael D.

    2015-01-01

    Over half of T cell acute lymphoblastic leukemia (T-ALL) patients have activating mutations in the Notch gene. Moreover, the contaminant 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD) is a known carcinogen that mediates its toxicity through the aryl hydrocarbon receptor (AHR), and crosstalk between activated AHR and Notch signaling pathways has previously been observed. Given the importance of Notch signaling in thymocyte development and T-ALL disease progression, we hypothesized that the activated AHR potentiates disease initiation and progression in an in vivo model of Notch1-induced thymoma. This hypothesis was tested utilizing adult and developmental exposure paradigms to TCDD in mice expressing a constitutively active Notch1 transgene (Notch ICN-TG ). Following exposure of adult Notch ICN-TG mice to a single high dose of TCDD, we observed a significant increase in the efficiency of CD8 thymocyte generation. We next exposed pregnant mice to 3 μg/kg of TCDD throughout gestation and lactation to elucidate effects of developmental AHR activation on later-life T cell development and T-ALL-like thymoma susceptibility induced by Notch1. We found that the vehicle-exposed Notch ICN-TG offspring have a peripheral T cell pool heavily biased toward the CD4 lineage, while TCDD-exposed Notch ICN-TG offspring were biased toward the CD8 lineage. Furthermore, while the vehicle-exposed NotchICN-TG mice showed increased splenomegaly and B to T cell ratios indicative of disease, mice developmentally exposed to TCDD were largely protected from disease. These studies support a model where developmental AHR activation attenuates later-life Notch1-dependent impacts on thymocyte development and disease progression. - Highlights: • Adult mice exposed to 30 μg/kg TCDD have higher efficiency of CD8 thymocyte generation. • Mice carrying a constitutively active Notch transgene were exposed to 3 μg/kg TCDD throughout development. • Progression of Notch-induced thymoma was different in

  6. Developmental exposure to 2,3,7,8 tetrachlorodibenzo-p-dioxin attenuates later-life Notch1-mediated T cell development and leukemogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Ahrenhoerster, Lori S.; Leuthner, Tess C.; Tate, Everett R.; Lakatos, Peter A.; Laiosa, Michael D., E-mail: laiosa@uwm.edu

    2015-03-01

    Over half of T cell acute lymphoblastic leukemia (T-ALL) patients have activating mutations in the Notch gene. Moreover, the contaminant 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD) is a known carcinogen that mediates its toxicity through the aryl hydrocarbon receptor (AHR), and crosstalk between activated AHR and Notch signaling pathways has previously been observed. Given the importance of Notch signaling in thymocyte development and T-ALL disease progression, we hypothesized that the activated AHR potentiates disease initiation and progression in an in vivo model of Notch1-induced thymoma. This hypothesis was tested utilizing adult and developmental exposure paradigms to TCDD in mice expressing a constitutively active Notch1 transgene (Notch{sup ICN-TG}). Following exposure of adult Notch{sup ICN-TG} mice to a single high dose of TCDD, we observed a significant increase in the efficiency of CD8 thymocyte generation. We next exposed pregnant mice to 3 μg/kg of TCDD throughout gestation and lactation to elucidate effects of developmental AHR activation on later-life T cell development and T-ALL-like thymoma susceptibility induced by Notch1. We found that the vehicle-exposed Notch{sup ICN-TG} offspring have a peripheral T cell pool heavily biased toward the CD4 lineage, while TCDD-exposed Notch{sup ICN-TG} offspring were biased toward the CD8 lineage. Furthermore, while the vehicle-exposed NotchICN-TG mice showed increased splenomegaly and B to T cell ratios indicative of disease, mice developmentally exposed to TCDD were largely protected from disease. These studies support a model where developmental AHR activation attenuates later-life Notch1-dependent impacts on thymocyte development and disease progression. - Highlights: • Adult mice exposed to 30 μg/kg TCDD have higher efficiency of CD8 thymocyte generation. • Mice carrying a constitutively active Notch transgene were exposed to 3 μg/kg TCDD throughout development. • Progression of Notch

  7. Evaluation of fracture toughness in dental ceramics using indentation and SEVNB (Single Edge V-Notched Beam)-method; Avaliacao da tenacidade a fratura de ceramicas dentarias atraves do metodo de entalhe - SEVNB (Single Edge V-Notched Beam)

    Energy Technology Data Exchange (ETDEWEB)

    Santos, L.A.; Santos, C.; Souza, R.C.; Ribeiro, S. [Universidade de Sao Paulo (DEMAR/EEL/USP), Lorena, SP (Brazil). Escola de Engenharia de Lorena. Dept. de Engenharia de Materiais. Polo Urbo-Industrial; Strecker, K. [Universidade Federal de Sao Joao del-Rei (DME/UFSJ), MG (Brazil). Dept. de Materiais Eletricos; Oberacker, R. [Karlsruhe Univ. (Germany)

    2009-07-01

    In this work, the fracture toughness of different ceramics based on Al{sub 2}O{sub 3} and ZrO{sub 2} were evaluated using, comparatively two methods, Vickers indentation and SEVNB (Single Edge V-Notched Beam) method. Al{sub 2}O{sub 3}, ZrO{sub 2}(3%Y{sub 2}O{sub 3}) micro-particled and ZrO{sub 2}(3%Y{sub 2}O{sub 3}) nanometric, ZrO{sub 2}-Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}-ZrO{sub 2} composites were sintered at different temperatures. Samples were characterized by relative density, X-ray diffraction, SEM, and mechanical evaluation by hardness, bending strength and fracture toughness obtained by ickers indentation and SEVNB-method. The results were presented comparing the densification and microstructural results. Furthermore, the advantages and limitations of each method were discussed. (author)

  8. Survey of postirradiation heat treatment as a means to mitigate radiation embrittlement of reactor vessel steels

    International Nuclear Information System (INIS)

    Hawthorne, J.R.

    1979-01-01

    Nuclear-radiation service typically produces a progressive reduction in the notch ductility of low-alloy steels. The reduction is manifested by a decrease in Charpy-V (Csub(v)) upper-shelf energy level and by an elevation in temperature of the ductile-to-brittle transition. Post irradiation heat treatment (annealing) is being investigated as a method for the reversal of these detrimental radiation effects for reactor-vessel steels. This study was undertaken to analyze factors which could affect annealing response, report data available to qualify suspected influences on annealing, and summarize experimental results generated for many commercially produced reactor materials and companion materials produced in the laboratory

  9. Loss of PTB or negative regulation of Notch mRNA reveals distinct zones of Notch and actin protein accumulation in Drosophila embryo.

    Directory of Open Access Journals (Sweden)

    Cedric S Wesley

    Full Text Available Polypyrimidine Tract Binding (PTB protein is a regulator of mRNA processing and translation. Genetic screens and studies of wing and bristle development during the post-embryonic stages of Drosophila suggest that it is a negative regulator of the Notch pathway. How PTB regulates the Notch pathway is unknown. Our studies of Drosophila embryogenesis indicate that (1 the Notch mRNA is a potential target of PTB, (2 PTB and Notch functions in the dorso-lateral regions of the Drosophila embryo are linked to actin regulation but not their functions in the ventral region, and (3 the actin-related Notch activity in the dorso-lateral regions might require a Notch activity at or near the cell surface that is different from the nuclear Notch activity involved in cell fate specification in the ventral region. These data raise the possibility that the Drosophila embryo is divided into zones of different PTB and Notch activities based on whether or not they are linked to actin regulation. They also provide clues to the almost forgotten role of Notch in cell adhesion and reveal a role for the Notch pathway in cell fusions.

  10. Loss of PTB or Negative Regulation of Notch mRNA Reveals Distinct Zones of Notch and Actin Protein Accumulation in Drosophila Embryo

    Science.gov (United States)

    Wesley, Cedric S.; Guo, Heng; Chaudhry, Kanita A.; Thali, Markus J.; Yin, Jerry C.; Clason, Todd; Wesley, Umadevi V.

    2011-01-01

    Polypyrimidine Tract Binding (PTB) protein is a regulator of mRNA processing and translation. Genetic screens and studies of wing and bristle development during the post-embryonic stages of Drosophila suggest that it is a negative regulator of the Notch pathway. How PTB regulates the Notch pathway is unknown. Our studies of Drosophila embryogenesis indicate that (1) the Notch mRNA is a potential target of PTB, (2) PTB and Notch functions in the dorso-lateral regions of the Drosophila embryo are linked to actin regulation but not their functions in the ventral region, and (3) the actin-related Notch activity in the dorso-lateral regions might require a Notch activity at or near the cell surface that is different from the nuclear Notch activity involved in cell fate specification in the ventral region. These data raise the possibility that the Drosophila embryo is divided into zones of different PTB and Notch activities based on whether or not they are linked to actin regulation. They also provide clues to the almost forgotten role of Notch in cell adhesion and reveal a role for the Notch pathway in cell fusions. PMID:21750738

  11. Evaluation of fracture toughness in dental ceramics using indentation and SEVNB (Single Edge V-Notched Beam)-method

    International Nuclear Information System (INIS)

    Santos, L.A.; Santos, C.; Souza, R.C.; Ribeiro, S.

    2009-01-01

    In this work, the fracture toughness of different ceramics based on Al 2 O 3 and ZrO 2 were evaluated using, comparatively two methods, Vickers indentation and SEVNB (Single Edge V-Notched Beam) method. Al 2 O 3 , ZrO 2 (3%Y 2 O 3 ) micro-particled and ZrO 2 (3%Y 2 O 3 ) nanometric, ZrO 2 -Al 2 O 3 and Al 2 O 3 -ZrO 2 composites were sintered at different temperatures. Samples were characterized by relative density, X-ray diffraction, SEM, and mechanical evaluation by hardness, bending strength and fracture toughness obtained by ickers indentation and SEVNB-method. The results were presented comparing the densification and microstructural results. Furthermore, the advantages and limitations of each method were discussed. (author)

  12. Notch Signaling: Piercing a Harness of Simplicity

    NARCIS (Netherlands)

    Helbig, Christina; Amsen, Derk

    2015-01-01

    The Notch pathway is an attractive therapeutic target for treatment of cancer and T cell-mediated pathology, but Notch inhibition leads to many side effects. Pinnell et al. (2015) demonstrate that oncogenic functions can be separated biochemically from other functions of Notch, opening new options

  13. Instrumentation of a Charpy-pendulum. Additional data obtained from it and its application to nuclear reactor pressure vessels surveillance programs

    International Nuclear Information System (INIS)

    Chomik, Enrique P.; Dhers, Horacio; Iorio, Antonio F.; Ciriani, Dario F.

    1999-01-01

    Charpy test gives information about a material dynamic fracture behavior. In a plain Charpy test, this information is the absorbed energy during fracture of the specimen, lateral deformation and the percentage of ductile fracture of the specimen. These parameters can then be used for the determination of the material response to a dynamic applied load, and are used at present to determine the brittle-ductile transition temperature of a material. However, there is a lot of additional information that can be obtained from a Charpy test, which is vital for the case of surveillance programs of nuclear power plants, where it is necessary to get the most available information from the specimens to be tested, because each one of them was irradiated for many years under temperature and neutronic flux conditions similar to that of the internal surface of the reactor pressure vessel, which converts these specimens in unique and very expensive ones. This additional information can be obtained from the curve that determines the evolution of the applied force to the specimen throughout the time involved in its fracture. It was possible to instrument a Charpy pendulum at a fraction of the cost necessary to buy an instrumentation package like the ones available in the market, and since the instrumentation equipment obtained is easy to transport. It has the additional advantage that can be used to instrument any other pendulum replacing only the hammer of the pendulum with a instrumented one for that pendulum. (author)

  14. Notch3 signalling promotes tumour growth in colorectal cancer.

    Science.gov (United States)

    Serafin, Valentina; Persano, Luca; Moserle, Lidia; Esposito, Giovanni; Ghisi, Margherita; Curtarello, Matteo; Bonanno, Laura; Masiero, Massimo; Ribatti, Domenico; Stürzl, Michael; Naschberger, Elisabeth; Croner, Roland S; Jubb, Adrian M; Harris, Adrian L; Koeppen, Hartmut; Amadori, Alberto; Indraccolo, Stefano

    2011-08-01

    Increased Notch1 activity has been observed in intestinal tumours, partially accomplished by β-catenin-mediated up-regulation of the Notch ligand Jagged-1. Whether further mechanisms of Notch activation exist and other Notch receptors might be involved is unclear. Microarray data indicated that Notch3 transcript levels are significantly up-regulated in primary and metastatic CRC samples compared to normal mucosa. Moreover, Notch3 protein was expressed at strong/moderate levels by 19.7% of 158 CRC samples analysed, and at weak levels by 51.2% of the samples. Intrigued by these findings, we sought to investigate whether Notch3 modulates oncogenic features of CRC cells. By exploiting xenografts of CRC cells with different tumourigenic properties in mice, we found that the aggressive phenotype was associated with altered expression of components of the Notch pathway, including Notch3, Delta-like 4 (DLL4), and Jagged-1 ligands. Stimulation with immobilized recombinant DLL4 or transduction with DLL4-expressing vectors dramatically increased Notch3 expression in CRC cells, associated with accelerated tumour growth. Forced expression of an active form of Notch3 mirrored the effects of DLL4 stimulation and increased tumour formation. Conversely, attenuation of Notch3 levels by shRNA resulted in perturbation of the cell cycle followed by reduction in cell proliferation, clonogenic capacity, and inhibition of tumour growth. Altogether, these findings indicate that Notch3 can modulate the tumourigenic properties of CRC cells and contributes to sustained Notch activity in DLL4-expressing tumours. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

  15. A potentiometric biosensor for the detection of notch 3 using functionalized ZnO nanorods.

    Science.gov (United States)

    Ibupoto, Z H; Khun, K; Liu, X; Willander, M

    2014-09-01

    The notch signalling plays a vital and radical role for the activity of cellular proliferation, differentiation and apoptosis. In this study, for the first time a particular biosensor is developed for the detection of notch 3. ZnO nanorods were fabricated on the gold coated glass substrate by hydrothermal method and afterwards were decorated with the gold nanoparticles by electrodepositing technique. Scanning electron microscopy (SEM) has shown the perpendicular to the substrate growth pattern of ZnO nanorods. X-ray diffraction (XRD) studies showed the c-axis oriented growth direction with wurtzite crystal structure of ZnO nanorods. X-ray Photoelectron Spectroscopy (XPS) and energy dispersive X-ray (EDX) techniques have shown the presence of Zn, O and Au atoms in the prepared functional material. Furthermore, the anti-notch 3 was physically adsorbed on the gold nanoparticles functionalized ZnO nanorods. The developed potentiometric immunosensor has shown response to the wide range of notch 3 molecules. The detected range included 1.00 x 10(-5)-1.50 x 10(0 ) μg/mL with a sensitivity of 23.15 ± 0.31 mV/decade. The analytical parameters including reproducibility, stability, and selectivity were also investigated and the observed results indicate the acceptable performance of the notch 3 biosensor. Moreover, the proposed notch 3 biosensor exhibited a fast response time of 10 s.

  16. Metallurgical interpretation of the change of notched bar impact strength in the heat-affected zone of weldable structural steels

    International Nuclear Information System (INIS)

    Forch, K.; Forch, U.; Piehl, K.H.

    1978-01-01

    Notched bar impact energy in the heat-affected zone of joint welds of the steels StE 36, StE 51 and 20 MnMoNi55. Manual arc welding and submerged arc welding with heat input between 10,000 and 35,000 J/cm, stress relieving between 530 and 600 0 C. Significance of the structure in the heat-affected zone, the effect of heat treatment, the precipitation processes and of temper embrittlement. (orig.) [de

  17. Excessive Anteversion Leads to Failure at 3 Years Due to Impingement as Evidenced by Twin Notches in Ti6A4V Stem

    Directory of Open Access Journals (Sweden)

    Thomas Donaldson

    2015-08-01

    Full Text Available A 63-year old female with bilateral hip replacements was referred to our clinic for pain and elevated metal ions. Her left hip had been revised earlier. The right hip had an SROM Ti6Al4V stem implanted with a 28mm head, a 28mm CoCr liner and Pinnacle Ti6Al4V shell. The patient reported pain, numbness, tingling, and repeated clicking and popping sensations with gait. She specifically noted that her hip would freeze while walking and could pop rising from a chair. Repeated metal ion levels showed Co (blood17ppb, Cr (serum 21ppb, and Ti (blood at 69ppb. CT-images of right hip revealed femoral stem anteversion was 43° and cup anteversion was 40°, for a combined anteversion of 83°. The right hip was revised 3.5 years postoperatively for persistent pain and elevated metal ions. At surgery, large twin notches were evident on her posterior femoral neck and 10mm-wide scalloped damage was evident in the rim of the Ti6A4V shell. SEM-imaging revealed contaminating layers on CoCr head containing elements Al, V and Ti. These indicated that titanium-alloy particles liberated by cup-to-neck impingements had transferred to the CoCr bearings. Our intent in this case was not to document that a MOM bearing produced impingement damage, because this case clearly implicated adverse surgical positioning. Rather, the intent was to document sequelae likely in a THA case that has a metal cup impinging on a metal femoral neck. In particular, twin notches on the femoral neck indicated that this patient was routinely impinging her Ti6Al4V shell against the Ti6Al4V neck and also subluxing her femoral head out of the cup. These signs are a clear indication that one or both components must be revised, as opposed to simply replacing the CoCr liner with a revision polyethylene liner.

  18. Notch signaling and progenitor/ductular reaction in steatohepatitis.

    Directory of Open Access Journals (Sweden)

    Carola M Morell

    Full Text Available Persistent hepatic progenitor cells (HPC activation resulting in ductular reaction (DR is responsible for pathologic liver repair in cholangiopathies. Also, HPC/DR expansion correlates with fibrosis in several chronic liver diseases, including steatohepatitis. Increasing evidence indicates Notch signaling as a key regulator of HPC/DR response in biliary and more in general liver injuries. Therefore, we aimed to investigate the role of Notch during HPC/DR activation in a mouse model of steatohepatitis.Steatohepatitis was generated using methionine-choline deficient (MCD diet. For hepatocyte lineage tracing, R26R-YFP mice were infected with AAV8-TBG-Cre.MCD diet promoted a strong HPC/DR response that progressively diffused in the lobule, and correlated with increased fibrosis and TGF-β1 expression. Notch signaling was unchanged in laser-capture microdissected HPC/DR, whereas Notch receptors were down regulated in hepatocytes. However, in-vivo lineage tracing experiments identified discrete hepatocytes showing Notch-1 activation and expressing (the Notch-dependent Sox9. Stimulation of AML-12 hepatocyte-cell line with immobilized Jag1 induced Sox9 and down-regulated albumin and BSEP expression. TGF-β1 treatment in primary hepatic stellate cells (HSC induced Jag1 expression. In MCD diet-fed mice, αSMA-positive HSC were localized around Sox9 expressing hepatocytes, suggesting that Notch activation in hepatocytes was promoted by TGF-β1 stimulated HSC. In-vivo Notch inhibition reduced HPC response and fibrosis progression.Our data suggest that Notch signaling is an important regulator of DR and that in steatohepatitis, hepatocytes exposed to Jag1-positive HSC, contribute to pathologic DR by undergoing Notch-mediated differentiation towards an HPC-like phenotype. Given the roles of Notch in fibrosis and liver cancer, these data suggest mesenchymal expression of Jag1 as an alternative therapeutic target.

  19. Oncogenic Notch signaling in T-cell and B-cell lymphoproliferative disorders.

    Science.gov (United States)

    Chiang, Mark Y; Radojcic, Vedran; Maillard, Ivan

    2016-07-01

    This article highlights recent discoveries about Notch activation and its oncogenic functions in lymphoid malignancies, and discusses the therapeutic potential of Notch inhibition. NOTCH mutations arise in a broad spectrum of lymphoid malignancies and are increasingly scrutinized as putative therapeutic targets. In T-cell acute lymphoblastic leukemia (T-ALL), NOTCH1 mutations affect the extracellular negative regulatory region and lead to constitutive Notch activation, although mutated receptors remain sensitive to Notch ligands. Other NOTCH1 mutations in T-ALL and NOTCH1/2 mutations in multiple B-cell malignancies truncate the C-terminal proline (P), glutamic acid (E), serine (S), threonine (T)-rich (PEST) domain, leading to decreased Notch degradation after ligand-mediated activation. Thus, targeting Notch ligand-receptor interactions could provide therapeutic benefits. In addition, we discuss recent reports on clinical testing of Notch inhibitors in T-ALL that influenced contemporary thinking on the challenges of targeting Notch in cancer. We review advances in the laboratory to address these challenges in regards to drug targets, the Notch-driven metabolome, and the sophisticated protein-protein interactions at Notch-dependent superenhancers that underlie oncogenic Notch functions. Notch signaling is a recurrent oncogenic pathway in multiple T- and B-cell lymphoproliferative disorders. Understanding the complexity and consequences of Notch activation is critical to define optimal therapeutic strategies targeting the Notch pathway.

  20. Role of Notch signaling in the mammalian heart

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, X.L.; Liu, J.C. [Department of Cardiac Surgery, The First Affiliated Hospital, Nanchang University, Donghu District, Nanchang, Jiangxi (China)

    2013-12-12

    Notch signaling is an evolutionarily ancient, highly conserved pathway important for deciding cell fate, cellular development, differentiation, proliferation, apoptosis, adhesion, and epithelial-to-mesenchymal transition. Notch signaling is also critical in mammalian cardiogenesis, as mutations in this signaling pathway are linked to human congenital heart disease. Furthermore, Notch signaling can repair myocardial injury by promoting myocardial regeneration, protecting ischemic myocardium, inducing angiogenesis, and negatively regulating cardiac fibroblast-myofibroblast transformation. This review provides an update on the known roles of Notch signaling in the mammalian heart. The goal is to assist in developing strategies to influence Notch signaling and optimize myocardial injury repair.

  1. Rapid measurement of auditory filter shape in mice using the auditory brainstem response and notched noise.

    Science.gov (United States)

    Lina, Ioan A; Lauer, Amanda M

    2013-04-01

    The notched noise method is an effective procedure for measuring frequency resolution and auditory filter shapes in both human and animal models of hearing. Briefly, auditory filter shape and bandwidth estimates are derived from masked thresholds for tones presented in noise containing widening spectral notches. As the spectral notch widens, increasingly less of the noise falls within the auditory filter and the tone becomes more detectible until the notch width exceeds the filter bandwidth. Behavioral procedures have been used for the derivation of notched noise auditory filter shapes in mice; however, the time and effort needed to train and test animals on these tasks renders a constraint on the widespread application of this testing method. As an alternative procedure, we combined relatively non-invasive auditory brainstem response (ABR) measurements and the notched noise method to estimate auditory filters in normal-hearing mice at center frequencies of 8, 11.2, and 16 kHz. A complete set of simultaneous masked thresholds for a particular tone frequency were obtained in about an hour. ABR-derived filter bandwidths broadened with increasing frequency, consistent with previous studies. The ABR notched noise procedure provides a fast alternative to estimating frequency selectivity in mice that is well-suited to high through-put or time-sensitive screening. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. An energetic criterion for a micro-crack of finite length initiated in orthotropic bi-material notches

    Czech Academy of Sciences Publication Activity Database

    Profant, T.; Klusák, Jan; Ševeček, O.; Hrstka, M.; Kotoul, M.

    2013-01-01

    Roč. 110, SEP (2013), s. 396-409 ISSN 0013-7944 R&D Projects: GA ČR(CZ) GAP108/10/2049; GA ČR(CZ) GA101/09/1821 Institutional support: RVO:68081723 Keywords : crack initiation * bi-material notch * orthotropic bi-material notch * singular stress concentrator Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.662, year: 2013

  3. Mechanical properties of as-cast microalloyed steels produced via investment casting

    International Nuclear Information System (INIS)

    Najafi, H.; Rassizadehghani, J.; Norouzi, S.

    2011-01-01

    Tensile and room temperature Charpy V-notch impact tests were used to evaluate the variations in the as-cast mechanical properties of a low-carbon steel produced via shell mould investment casting and containing combinations of vanadium, niobium and titanium. Tensile results indicate that the yield strength and ultimate tensile strength (UTS) have increased up to respectively 615 MPa and 770 MPa due to the fine-scale microalloy precipitates in the microalloyed samples. Room temperature impact test results show that while addition of vanadium individually has not changed the impact energy, Nb has decreased it considerably. However, examination of fracture surfaces reveals that all microalloyed samples have failed by transgranular cleavage. Based on the transmission electron microscope (TEM) studies, it seems that carbonitrides being greater than 50 nm in size and formed along prior austenite grain boundaries before γ transformation are responsible for the observed reduction in impact energies and brittle fracture. In comparison to sand mould casting, the yield and UTS obtained from investment casting are superior. Furthermore, although the impact energies of Nb-containing alloys are approximately the same as those obtained from sand moulds, the impact energy of the alloy containing only vanadium has improved considerably.

  4. Common nonmutational NOTCH1 activation in chronic lymphocytic leukemia.

    Science.gov (United States)

    Fabbri, Giulia; Holmes, Antony B; Viganotti, Mara; Scuoppo, Claudio; Belver, Laura; Herranz, Daniel; Yan, Xiao-Jie; Kieso, Yasmine; Rossi, Davide; Gaidano, Gianluca; Chiorazzi, Nicholas; Ferrando, Adolfo A; Dalla-Favera, Riccardo

    2017-04-04

    Activating mutations of NOTCH1 (a well-known oncogene in T-cell acute lymphoblastic leukemia) are present in ∼4-13% of chronic lymphocytic leukemia (CLL) cases, where they are associated with disease progression and chemorefractoriness. However, the specific role of NOTCH1 in leukemogenesis remains to be established. Here, we report that the active intracellular portion of NOTCH1 (ICN1) is detectable in ∼50% of peripheral blood CLL cases lacking gene mutations. We identify a "NOTCH1 gene-expression signature" in CLL cells, and show that this signature is significantly enriched in primary CLL cases expressing ICN1, independent of NOTCH1 mutation. NOTCH1 target genes include key regulators of B-cell proliferation, survival, and signal transduction. In particular, we show that NOTCH1 transactivates MYC via binding to B-cell-specific regulatory elements, thus implicating this oncogene in CLL development. These results significantly extend the role of NOTCH1 in CLL pathogenesis, and have direct implications for specific therapeutic targeting.

  5. Essential Role of Endothelial Notch1 in Angiogenesis

    Science.gov (United States)

    Limbourg, Florian P.; Takeshita, Kyosuke; Radtke, Freddy; Bronson, Roderick T.; Chin, Michael T.; Liao, James K.

    2009-01-01

    Background Notch signaling influences binary cell fate decisions in a variety of tissues. The Notch1 receptor is widely expressed during embryogenesis and is essential for embryonic development. Loss of global Notch1 function results in early embryonic lethality, but the cell type responsible for this defect is not known. Here, we identify the endothelium as the primary target tissue affected by Notch1 signaling. Methods and Results We generated an endothelium-specific deletion of Notch1 using Tie2Cre and conditional Notch1flox/flox mice. Mutant embryos lacking endothelial Notch1 died at approximately embryonic day 10.5 with profound vascular defects in placenta, yolk sac, and embryo proper, whereas heterozygous deletion had no effect. In yolk sacs of mutant embryos, endothelial cells formed a primary vascular plexus indicative of intact vasculogenesis but failed to induce the secondary vascular remodeling required to form a mature network of well-organized large and small blood vessels, which demonstrates a defect in angiogenesis. These vascular defects were also evident in the placenta, where blood vessels failed to invade the placental labyrinth, and in the embryo proper, where defective blood vessel maturation led to pericardial and intersomitic hemorrhage. Enhanced activation of caspase-3 was detected in endothelial and neural cells of mutant mice, which resulted in enhanced apoptotic degeneration of somites and the neural tube. Conclusions These findings recapitulate the vascular phenotype of global Notch1-/- mutants and indicate an essential cell-autonomous role of Notch1 signaling in the endothelium during vascular development. These results may have important clinical implications with regard to Notch1 signaling in adult angiogenesis. PMID:15809373

  6. Void coalescence and fracture behavior of notched and un-notched tensile tested specimens in fine grain dual phase steel

    Energy Technology Data Exchange (ETDEWEB)

    Saeidi, N., E-mail: navidsae@gmail.com [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Ashrafizadeh, F.; Niroumand, B. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Forouzan, M.R.; Mohseni mofidi, S. [Department of Mechanical Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Barlat, F. [Materials Mechanics Laboratory (MML), Graduate Institute of Ferrous Technology (GIFT), Pohang University of Science and Technology POSTECH, San 31 Hyoja-dong, Nam-gu, Pohang, Gyeongbuk 790-784 (Korea, Republic of)

    2015-09-17

    Due to growing global concern about the environmental issues, steel developers have been forced by automobile makers to produce more efficient steel grades with high strength to weight ratios along with high crashworthiness performance. In order to find deficiencies of the existing steels and develop superior steel products, detailed understanding of deformation and damage behavior in the existing steels is needed. In the present research, deformation and damage evolution during room temperature uniaxial tensile test of a modern high strength Dual Phase Steel, i.e. DP780, were studied. Detailed scanning electron microscopy (SEM) examination of the microstructures of notched and un-notched tensile fractured specimens revealed that in notched specimen, plastic deformation was concentrated more within the notched region. Therefore, much higher reduction in thickness with a high reduction gradient occurred in this region, In the un-notched specimen, however, plastic deformation was more uniformly distributed in larger parts of the gauge length, and therefore, thickness reduction happened with a lower gradient. Although geometric notch on the specimen did not change the void nucleation and growth mechanisms, the kinetics of these phenomena was influenced. On the other hand, voids linkage mechanism tended to change from void coalescence in the un-notched specimen to void sheeting in the notched specimen. Moreover, three different models developed by Brown & Embury (BM), Thomason and Pardoen were employed to predict the final fracture strain. It was revealed that, BM model showed much more accurate predictions for the studied DP steel in comparison with those of Thomason and Pardoens’ models.

  7. Void coalescence and fracture behavior of notched and un-notched tensile tested specimens in fine grain dual phase steel

    International Nuclear Information System (INIS)

    Saeidi, N.; Ashrafizadeh, F.; Niroumand, B.; Forouzan, M.R.; Mohseni mofidi, S.; Barlat, F.

    2015-01-01

    Due to growing global concern about the environmental issues, steel developers have been forced by automobile makers to produce more efficient steel grades with high strength to weight ratios along with high crashworthiness performance. In order to find deficiencies of the existing steels and develop superior steel products, detailed understanding of deformation and damage behavior in the existing steels is needed. In the present research, deformation and damage evolution during room temperature uniaxial tensile test of a modern high strength Dual Phase Steel, i.e. DP780, were studied. Detailed scanning electron microscopy (SEM) examination of the microstructures of notched and un-notched tensile fractured specimens revealed that in notched specimen, plastic deformation was concentrated more within the notched region. Therefore, much higher reduction in thickness with a high reduction gradient occurred in this region, In the un-notched specimen, however, plastic deformation was more uniformly distributed in larger parts of the gauge length, and therefore, thickness reduction happened with a lower gradient. Although geometric notch on the specimen did not change the void nucleation and growth mechanisms, the kinetics of these phenomena was influenced. On the other hand, voids linkage mechanism tended to change from void coalescence in the un-notched specimen to void sheeting in the notched specimen. Moreover, three different models developed by Brown & Embury (BM), Thomason and Pardoen were employed to predict the final fracture strain. It was revealed that, BM model showed much more accurate predictions for the studied DP steel in comparison with those of Thomason and Pardoens’ models

  8. Effects of irradiation on initiation and crack-arrest toughness of two high-copper welds and on stainless steel cladding

    International Nuclear Information System (INIS)

    Nanstad, R.K.; Iskander, S.K.; Haggag, F.M.

    1990-01-01

    The objective of the study on the high-copper welds is to determine the effect of neutron irradiation on the shift and shape of the ASME K Ic and K Ia toughness curves. Two submerged-arc welds with copper contents of 0.23 and 0.31 wt % were commercially fabricated in 220-mm-thick plate. Compact specimens fabricated from these welds were irradiated at a nominal temperature of 288 degree C to fluences from 1.5 to 1.9 x 10 19 neutrons/cm 2 (>1 MeV). The fracture toughness test results show that the irradiation-induced shifts at 100 MPa/m were greater than the Charpy 41-J shifts by about 11 and 18 degree C. Mean curve fits indicate mixed results regarding curve shape changes, but curves constructed as lower boundaries to the data do indicate curves of lower slopes. A preliminary evaluation of the crack-arrest results shows that the neutron-irradiation induced crack-arrest toughness temperature shift is about the same as the Charpy V-notch impact temperature shift at the 41-J energy level. The shape of the lower bound curves (for the range of test temperatures covered), compared to those of the ASME K Ia curve did not appear to have been altered by the irradiation. Three-wire stainless steel weld overlay cladding was irradiated at 288 degree C to fluences of 2 and 5 x 10 19 neutrons/cm 2 (>1 MeV). Charpy 41-J temperature shifts of 13 and 28 degree C were observed, respectively. For the lower fluence only, 12.7-mm thick compact specimens showed decreases in both J Ic and the tearing modulus. Comparison of the fracture toughness results with typical plate and a low upper-shelf weld reveals that the irradiated stainless steel cladding possesses low ductile initiation fracture toughness comparable to the low upper-shelf weld. 8 refs., 12 figs., 2 tabs

  9. Notch effects in uniaxial tension specimens

    International Nuclear Information System (INIS)

    Delph, T.J.

    1979-03-01

    Results of a literature survey on the effect of notches on the time-dependent failure of uniaxial tension specimens at elevated temperatures are presented. Particular attention is paid to the failure of notched specimens containing weldments

  10. Stress concentration at notches

    CERN Document Server

    Savruk, Mykhaylo P

    2017-01-01

    This book compiles solutions of linear theory of elasticity problems for isotropic and anisotropic bodies with sharp and rounded notches. It contains an overview of established and recent achievements, and presents the authors’ original solutions in the field considered with extensive discussion. The volume demonstrates through numerous, useful examples the effectiveness of singular integral equations for obtaining exact solutions of boundary problems of the theory of elasticity for bodies with cracks and notches. Incorporating analytical and numerical solutions of the problems of stress concentrations in solid bodies with crack-like defects, this volume is ideal for scientists and PhD students dealing with the problems of theory of elasticity and fracture mechanics. Stands as a modern and extensive compendium of solutions to the problems of linear theory of elasticity of isotropic and anisotropic bodies with sharp and rounded notches; Adopts a highly reader-friendly layout of tables, charts, approximation ...

  11. Present status of mechanical testing technology at the Research Hot Laboratory

    International Nuclear Information System (INIS)

    Kizaki, M.; Tobita, T.; Koya, T.; Kikuchi, T.

    1993-01-01

    Mechanical tests of irradiated metallic materials at the Research Hot Laboratory(RHL) have been carried out for 30 years to support material research in JAERI and to evaluate the irradiation integrity of pressure vessel steel in commercial power plant. Two tensile testing machines and one Charpy impact testing machine are available for the examinations. One of the tensile testing machines has 1000 kgf load capacity under the vacuum of ∼ 10 -7 torr at the temperature of 1300degC max.. The other one has 10 tonf load capacity, and is utilized for the multi-purpose tests such as tensile and compressive tests in air atmosphere at the temperature between -160 and 900degC. Examinations cover tensile test, bending test, J ic fracture toughness test, low cycle fatigue test and so on. Charpy impact testing machine with notched-bar specimen is instrumented with 30 kgf-m capacity in the temperature range of -140 - 240 degC. To support these mechanical tests in RHL, special jigs, devices and instruments have been developed. (author)

  12. Charpy trend-curve development based on PWR surveillance date

    International Nuclear Information System (INIS)

    Guthrie, G.L.

    1983-01-01

    The formulas given in the text provide a useful method of predicting the irradiation induced increase in the 41 joule Charpy transition temperature for plate and weld material. The standard deviations for the least squares fits are 26.4 0 F for the weld equation and 15.6 0 F for the plat relationship. The current method of derivation produces an unbiased estimate of the fluence exponent, resulting in increased reliability for fluence extrapolations. The method given for error estimation provides a relatively rigorous procedure for calculating uncertainties and takes proper account of the effects of uncertainties in the independent variables in any given application of the formulas. 11 refs., 4 figs., 4 tabs

  13. Oxide formation and precipitation behaviors on interface of F82H steel joints during HIPing and hot pressing

    International Nuclear Information System (INIS)

    Kishimoto, H.; Ono, T.; Sakasegawa, H.; Tanigawa, H.; Ando, M.; Shibayama, T.; Kohno, Y.; Kohyama, A.

    2013-01-01

    Joining technologies for F82H steels are important issues for the development of fusion energy. The hot isostatic pressing (HIP) method is appropriate for consolidating the first wall of the blanket because of the flexibility of the shape of HIPed products. The HIP method is planned for fabricating a complex-shaped first wall component with built-in cooling channels; thus, accumulation of studies of microstructural and mechanical property changes, especially lower toughness of the HIPed joints, is essential. Present research aims to reveal the microstructural evolution of F82H joints fabricated by the HIP method compared with joints fabricated by hot pressing, focusing on the formation of oxides on the interface. F82H joints were characterized using 1/3-scale Charpy V-notch impact test, transmission electron microscope, scanning electron microscope, and electron probe analysis to survey the microstructural characteristics of the interface

  14. Thermal aging evaluation of cast austenitic stainless steel pipe

    International Nuclear Information System (INIS)

    Song, T. H.; Jung, I. S.

    2002-01-01

    24 years have been passed since Kori Unit 1 began its commercial operation, and 19 years have been passed since Kori Unit 2 began its commercial operation. As the end point of design life become closer, plant life extension and periodic safety assessment is paid more and more attention to by utility company. In this paper, the methodologies and results of cast austenitic stainless steel pipe thermal aging evaluations of both units have been presented in association with aging time of 10, 20, and 30 years and operating temperature, respectively. Life extension cases respectively. As a result of this, at the operating temperature of 280 .deg. C, thermal aging was not a problem as long as Charpy V-notch room temperature minimum impact energy is concerned. However, more than 300 .deg. C and 30 years of operating condition, we should perform detailed fracture mechanics analysis with CMTR of NPP pipe

  15. Comparison between instrumented precracked Charpy and compact specimen tests of carbon steels

    International Nuclear Information System (INIS)

    Nanstad, R.K.

    1980-01-01

    The General Atomic Company High Temperature Gas-Cooled Reactor (HTGR) is housed within a prestressed concrete reactor vessel (PCRV). Various carbon steel structural members serve as closures at penetrations in the vessel. A program of testing and evaluation is underway to determine the need for reference fracture toughness (K/sub IR/) and indexing procedures for these materials as described in Appendix G to Section III, ASME Code for light water reactor steels. The materials of interest are carbon steel forgings (SA508, Class 1) and plates (SA537, Classes 1 and 2) as well as weldments of these steels. The fracture toughness behavior is characterized with instrumented precracked Charpy V-votch specimens (PCVN) - slow-bend and dynamic - and compact specimens (10-mm and 25-mm thicknesses) using both linear elastic (ASTM E399) and elastic-plastic (equivalent Energy and J-Integral) analytical procedures. For the dynamic PCVN tests, force-time traces are analyzed according to the procedures of the Pressure Vessel Research Council (PVRC)/Metal Properties Council (MPC). Testing and analytical procedures are discussed and PCVN results are compared to those obtained with compact specimens

  16. The flow effect in the irradiation embrittlement in pressure vessel steels of nuclear power plants

    International Nuclear Information System (INIS)

    Kempf, Rodolfo A.; Cativa Tolosa, Sebastian; Fortis, Ana M.

    2009-01-01

    This paper deals with the advances in the study of the mechanical behavior of the Reactor Pressure Vessel steels under accelerate irradiations. The objective is to study the effect of lead factors on the interpretation of the mechanisms that induced the embrittlement of the RPV, like those of the reactors Atucha II and CAREM. It is described a device designed to irradiate Charpy specimens with V notch of SA-508 type 3 steel at power reactor temperature, installed in the RA-1 reactor. It is presented also an automatic digital image processing technique for partitioning Charpy fracture surface into regions with a clear physical meaning and appropriate for the work in hot cells. The aim is to obtain the fracture behavior of irradiated specimens with different lead factors in the range of high fluencies and to know the dependence with the composition of the alloy and with the diffusion of other alloy elements. (author)

  17. Correlation of irradiation-induced transition temperature increases from C sub v and K sub Jc /K sub Ic data

    Energy Technology Data Exchange (ETDEWEB)

    Hiser, A.L. (Materials Engineering Associates, Inc., Lanham, MD (USA))

    1990-03-01

    Reactor pressure vessel (RPV) surveillance capsules contain Charpy-V (C{sub v}) specimens, but many do not contain fracture toughness specimens; accordingly, the radiation-induced shift (increase) in the brittle-to-ductile transition region ({Delta}T) is based upon the {Delta}T determined from notch ductility (C{sub v}) tests. Since the ASME K{sub Ic} and K{sub IR} reference fracture toughness curves are shifted by the {Delta}T from C{sub v}, assurance that this {Delta}T does not underestimate {Delta}T associated with the actual irradiated fracture toughness is required to provide confidence that safety margins do not fall below assumed levels. To assess this behavior, comparisons of {Delta}T's defined by elastic-plastic fracture toughness and C{sub v} tests have been made using data from RPV base and weld metals in which irradiations were made under test reactor conditions. Using as-measure'' fracture toughness values (K{sub Jc}), average comparisons between {Delta}T(C{sub v}) and {Delta}T(K{sub Jc}) are: (a) All data: {Delta}T(K{sub Jc} 100 MPa{radical}{bar m}) = {Delta}T(C{sub v} 41 J) +10{degree}C; (b) Plates only: {Delta}T(K{sub Jc} 100 MPa{radical}{bar m}) = {Delta}T(C{sub v} 41 J) +15{degree}C; and (c) Welds only: {Delta}T(K{sub Jc} 100 MPa{radical}{bar m}) = {Delta}T(C{sub v} 41 J) {minus}1{degree}C. Fluence rate is found to have no significant effect on the relationship between {Delta}T(C{sub v}) and {Delta}T(K{sub Jc}). 12 refs., 12 figs., 5 tabs.

  18. Prediction of the brittle fracture toughness value of a RPV steel from the analysis of a limited set of Charpy results

    International Nuclear Information System (INIS)

    Forget, P.; Marini, B.; Verdiere, N.

    2001-01-01

    Our objective is to establish a method to be able to determine fracture toughness of a reactor pressure vessel (RPV) by using the small number of Charpy specimens used in the reactor surveillance program. Previous studies have shown that it is possible to determine fracture toughness from Charpy tests. Another point is to determine if statistical effects are compatible with a restricted number of specimens, this paper deals with this point and presents a methodology that is applicable to the case of irradiated materials from the surveillance program. Several conclusions can be drawn from this study: -) When determining failure parameters, we gain most accuracy by increasing the number of samples from 3 to about 6; -) it is possible to evaluate brittle fracture toughness using local approach, either by using Beremin or Renevey model; -) The effect of using a small number of Charpy specimens to determine fracture toughness in brittle fracture is evaluated. The error in the evaluation of fracture toughness is much smaller than the experimental dispersion itself. (A.C.)

  19. Effect of Reheating Temperature and Cooling Treatment on the Microstructure, Texture, and Impact Transition Behavior of Heat-Treated Naval Grade HSLA Steel

    Science.gov (United States)

    Sk, Md. Basiruddin; Ghosh, A.; Rarhi, N.; Balamuralikrishnan, R.; Chakrabarti, D.

    2017-07-01

    In order to achieve the desired mechanical properties [YS > 390 MPa, total elongation >16 pct and Charpy impact toughness of 78 J at 213 K (-60 °C)] for naval application, samples from a low-carbon microalloyed steel have been subjected to different austenitization (1223 K to 1523 K) (950 °C to 1250 °C) and cooling treatments (furnace, air, or water cooling). The as-rolled steel and the sample air cooled from 1223 K (950 °C) could only achieve the required tensile properties, while the sample furnace cooled from 1223 K (950 °C) showed the best Charpy impact properties. Water quenching from 1223 K (950 °C) certainly contributed to the strength but affected the impact toughness. Overall, predominantly ferrite matrix with fine effective grain size and intense gamma-fiber texture was found to be beneficial for impact toughness as well as impact transition behavior. Small size and fraction of precipitates (like TiN, Nb, and V carbonitrides) eliminated the possibility of particle-controlled crack propagation and grain size-controlled crack propagation led to cleavage fracture. A simplified analytical approach has been used to explain the difference in impact transition behavior of the investigated samples.

  20. Deep lateral notch sign and double notch sign in complete tears of the anterior cruciate ligament: MR imaging evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Grimberg, Alexandre [University of California, San Diego School of Medicine, Division of Musculoskeletal Radiology, Department of Radiology, San Diego, CA (United States); Universidade Federal de Sao Paulo, Department of Diagnostic Imaging, Sao Paulo, SP (Brazil); Shirazian, Hoda; Torshizy, Hamid; Smitaman, Edward; Resnick, Donald L. [University of California, San Diego School of Medicine, Division of Musculoskeletal Radiology, Department of Radiology, San Diego, CA (United States); Chang, Eric Y. [Veterans Administrations San Diego Healthcare Systems, Osteoradiology Section, Department of Radiology, San Diego, CA (United States); University of California, San Diego School of Medicine, Division of Musculoskeletal Radiology, Department of Radiology, San Diego, CA (United States)

    2014-11-20

    To systematically compare the notches of the lateral femoral condyle (LFC) in patients with and without complete tears of the anterior cruciate ligament (ACL) in MR studies by (1) evaluating the dimensions of the lateral condylopatellar sulcus; (2) evaluating the presence and appearance of an extra or a double notch and its association with such tears. This retrospective study was approved by our institutional review board, and informed written patient consent was waived. In 58 cases of complete ACL tears and 37 control cases with intact ACL, the number of notches on the LFC was determined, and the depth and anteroposterior (AP) length of each notch were measured in each third of the LFC. The chi-square test, t-test, and logistic regression model were used to analyze demographic data and image findings, as appropriate. Presence of more than one notch demonstrated a sensitivity of 17.2 %, specificity of 100 %, positive predictive value of 100 %, and negative predictive value of 43.5 % for detecting a complete ACL tear. Lateral third depth measurement (p = 0.028) was a significant associated finding with a complete ACL tear. A deep notch in the lateral third of the LFC is a significant associated finding with a complete ACL tear when compared with an ACL-intact control group, and the presence of more than one notch is a specific but insensitive sign of such a tear. (orig.)

  1. SOX1 links the function of neural patterning and Notch signalling in the ventral spinal cord during the neuron-glial fate switch

    Energy Technology Data Exchange (ETDEWEB)

    Genethliou, Nicholas; Panayiotou, Elena [The Cyprus Institute of Neurology and Genetics, Airport Avenue, No. 6, Agios Dometios, 2370 Nicosia (Cyprus); Department of Biological Sciences, University of Cyprus, P.O. Box 20537, 1678 Nicosia (Cyprus); Panayi, Helen; Orford, Michael; Mean, Richard; Lapathitis, George; Gill, Herman; Raoof, Sahir [The Cyprus Institute of Neurology and Genetics, Airport Avenue, No. 6, Agios Dometios, 2370 Nicosia (Cyprus); Gasperi, Rita De; Elder, Gregory [James J. Peters VA Medical Center, Research and Development (3F22), 130 West Kingsbridge Road, Bronx, NY 10468 (United States); Kessaris, Nicoletta; Richardson, William D. [Wolfson Institute for Biomedical Research and Research Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT (United Kingdom); Malas, Stavros, E-mail: smalas@cing.ac.cy [The Cyprus Institute of Neurology and Genetics, Airport Avenue, No. 6, Agios Dometios, 2370 Nicosia (Cyprus); Department of Biological Sciences, University of Cyprus, P.O. Box 20537, 1678 Nicosia (Cyprus)

    2009-12-25

    During neural development the transition from neurogenesis to gliogenesis, known as the neuron-glial ({Nu}/G) fate switch, requires the coordinated function of patterning factors, pro-glial factors and Notch signalling. How this process is coordinated in the embryonic spinal cord is poorly understood. Here, we demonstrate that during the N/G fate switch in the ventral spinal cord (vSC) SOX1 links the function of neural patterning and Notch signalling. We show that, SOX1 expression in the vSC is regulated by PAX6, NKX2.2 and Notch signalling in a domain-specific manner. We further show that SOX1 regulates the expression of Hes1 and that loss of Sox1 leads to enhanced production of oligodendrocyte precursors from the pMN. Finally, we show that Notch signalling functions upstream of SOX1 during this fate switch and is independently required for the acquisition of the glial fate perse by regulating Nuclear Factor I A expression in a PAX6/SOX1/HES1/HES5-independent manner. These data integrate functional roles of neural patterning factors, Notch signalling and SOX1 during gliogenesis.

  2. Magnetoresistance effect in permalloy nanowires with various types of notches

    Science.gov (United States)

    Gao, Y.; You, B.; Wang, J.; Yuan, Y.; Wei, L. J.; Tu, H. Q.; Zhang, W.; Du, J.

    2018-05-01

    Suppressing the stochastic domain wall (DW) motion in magnetic nanowires is of great importance for designing DW-related spintronic devices. In this work, we have investigated the pinning/depinning processes of DWs in permalloy nanowires with three different types of notches by using longitudinal magnetoresistance (MR) measurement. The averaged MR curves demonstrate that the stochastic DW depinning is suppressed partly or even completely by a transversely asymmetric notch. The single-shot MR curves show that how the resistance changes with the applied field also depends strongly on the notch type while the DW is pinned around the notch. In the case of two depinning fields, larger (smaller) change of resistance always corresponds to larger (smaller) depinning field, regardless of the notch type. These phenomena can be understood by that the spin structure around the notch changes differently with the notch type when the DW is traveling through the notch.

  3. Gauging NOTCH1 Activation in Cancer Using Immunohistochemistry.

    Directory of Open Access Journals (Sweden)

    Michael J Kluk

    Full Text Available Fixed, paraffin-embedded (FPE tissues are a potentially rich resource for studying the role of NOTCH1 in cancer and other pathologies, but tests that reliably detect activated NOTCH1 (NICD1 in FPE samples have been lacking. Here, we bridge this gap by developing an immunohistochemical (IHC stain that detects a neoepitope created by the proteolytic cleavage event that activates NOTCH1. Following validation using xenografted cancers and normal tissues with known patterns of NOTCH1 activation, we applied this test to tumors linked to dysregulated Notch signaling by mutational studies. As expected, frequent NICD1 staining was observed in T lymphoblastic leukemia/lymphoma, a tumor in which activating NOTCH1 mutations are common. However, when IHC was used to gauge NOTCH1 activation in other human cancers, several unexpected findings emerged. Among B cell tumors, NICD1 staining was much more frequent in chronic lymphocytic leukemia than would be predicted based on the frequency of NOTCH1 mutations, while mantle cell lymphoma and diffuse large B cell lymphoma showed no evidence of NOTCH1 activation. NICD1 was also detected in 38% of peripheral T cell lymphomas. Of interest, NICD1 staining in chronic lymphocytic leukemia cells and in angioimmunoblastic lymphoma was consistently more pronounced in lymph nodes than in surrounding soft tissues, implicating factors in the nodal microenvironment in NOTCH1 activation in these diseases. Among carcinomas, diffuse strong NICD1 staining was observed in 3.8% of cases of triple negative breast cancer (3 of 78 tumors, but was absent from 151 non-small cell lung carcinomas and 147 ovarian carcinomas. Frequent staining of normal endothelium was also observed; in line with this observation, strong NICD1 staining was also seen in 77% of angiosarcomas. These findings complement insights from genomic sequencing studies and suggest that IHC staining is a valuable experimental tool that may be useful in selection of

  4. Notch1 and 4 Signaling Responds to an Increasing Vascular Wall Shear Stress in a Rat Model of Arteriovenous Malformations

    Directory of Open Access Journals (Sweden)

    Jian Tu

    2014-01-01

    Full Text Available Notch signaling is suggested to promote the development and maintenance of cerebral arteriovenous malformations (AVMs, and an increasing wall shear stress (WSS contributes to AVM rupture. Little is known about whether WSS impacts Notch signaling, which is important for understanding the angiogenesis of AVMs. WSS was measured in arteriovenous fistulas (AVF surgically created in 96 rats at different time points over a period of 84 days. The expression of Notch receptors 1 and 4 and their ligands, Delta1 and 4, Jagged1, and Notch downstream gene target Hes1 was quantified in “nidus” vessels. The interaction events between Notch receptors and their ligands were quantified using proximity ligation assay. There was a positive correlation between WSS and time (r=0.97; P<0.001. The expression of Notch receptors and their ligands was upregulated following AVF formation. There was a positive correlation between time and the number of interactions between Notch receptors and their ligands aftre AVF formation (r=0.62, P<0.05 and a positive correlation between WSS and the number of interactions between Notch receptors and their ligands (r=0.87, P<0.005. In conclusion, an increasing WSS may contribute to the angiogenesis of AVMs by activation of Notch signaling.

  5. Dynamic plastic behaviour of a notched free-free beam subjected to step-loading at one end

    International Nuclear Information System (INIS)

    Zhang, Y.; Yang, J.L.

    2002-01-01

    A rigid perfectly plastic model is developed to study the initial, small deflection response of a free-free beam with an initial notch along its span under a concentrated step-loading suddenly applied at one end of the beam. Complete solutions are obtained for various combinations of the magnitude of the load, the location of the notch and its defect-severity. The partitioning of the initial energy dissipation rates is discussed for some typical situations. It is concluded that: (i) the different initial deformation mechanisms and the initial energy dissipation rate of the beam depend not only on the magnitude of the load but also on the defect-severity and location of the notch; (ii) because of the influence of the notch, the structural response of the beam is far more complicated than that of the un-notched free-free beam; and (iii) for some cases the maximum rate of energy dissipation in plastic hinges will be more than 1/3 of the total input energy rate, while for an un-notched free-free beam, it has been demonstrated that the plastic dissipated energy is always less than 1/3 of the input energy [Int. J. Impact Engng 21 (1998) 165

  6. Notch receptor expression in neurogenic regions of the adult zebrafish brain.

    Directory of Open Access Journals (Sweden)

    Vanessa de Oliveira-Carlos

    Full Text Available The adult zebrash brain has a remarkable constitutive neurogenic capacity. The regulation and maintenance of its adult neurogenic niches are poorly understood. In mammals, Notch signaling is involved in stem cell maintenance both in embryonic and adult CNS. To better understand how Notch signaling is involved in stem cell maintenance during adult neurogenesis in zebrafish we analysed Notch receptor expression in five neurogenic zones of the adult zebrafish brain. Combining proliferation and glial markers we identified several subsets of Notch receptor expressing cells. We found that 90 [Formula: see text] of proliferating radial glia express notch1a, notch1b and notch3. In contrast, the proliferating non-glial populations of the dorsal telencephalon and hypothalamus rarely express notch3 and about half express notch1a/1b. In the non-proliferating radial glia notch3 is the predominant receptor throughout the brain. In the ventral telencephalon and in the mitotic area of the optic tectum, where cells have neuroepithelial properties, notch1a/1b/3 are expressed in most proliferating cells. However, in the cerebellar niche, although progenitors also have neuroepithelial properties, only notch1a/1b are expressed in a high number of PCNA [Formula: see text] cells. In this region notch3 expression is mostly in Bergmann glia and at low levels in few PCNA [Formula: see text] cells. Additionally, we found that in the proliferation zone of the ventral telencephalon, Notch receptors display an apical high to basal low gradient of expression. Notch receptors are also expressed in subpopulations of oligodendrocytes, neurons and endothelial cells. We suggest that the partial regional heterogeneity observed for Notch expression in progenitor cells might be related to the cellular diversity present in each of these neurogenic niches.

  7. Identification of epidermal Pdx1 expression discloses different roles of Notch1 and Notch2 in murine Kras(G12D-induced skin carcinogenesis in vivo.

    Directory of Open Access Journals (Sweden)

    Pawel K Mazur

    Full Text Available BACKGROUND: The Ras and Notch signaling pathways are frequently activated during development to control many diverse cellular processes and are often dysregulated during tumorigenesis. To study the role of Notch and oncogenic Kras signaling in a progenitor cell population, Pdx1-Cre mice were utilized to generate conditional oncogenic Kras(G12D mice with ablation of Notch1 and/or Notch2. METHODOLOGY/PRINCIPAL FINDINGS: Surprisingly, mice with activated Kras(G12D and Notch1 but not Notch2 ablation developed skin papillomas progressing to squamous cell carcinoma providing evidence for Pdx1 expression in the skin. Immunostaining and lineage tracing experiments indicate that PDX1 is present predominantly in the suprabasal layers of the epidermis and rarely in the basal layer. Further analysis of keratinocytes in vitro revealed differentiation-dependent expression of PDX1 in terminally differentiated keratinocytes. PDX1 expression was also increased during wound healing. Further analysis revealed that loss of Notch1 but not Notch2 is critical for skin tumor development. Reasons for this include distinct Notch expression with Notch1 in all layers and Notch2 in the suprabasal layer as well as distinctive p21 and β-catenin signaling inhibition capabilities. CONCLUSIONS/SIGNIFICANCE: Our results provide strong evidence for epidermal expression of Pdx1 as of yet not identified function. In addition, this finding may be relevant for research using Pdx1-Cre transgenic strains. Additionally, our study confirms distinctive expression and functions of Notch1 and Notch2 in the skin supporting the importance of careful dissection of the contribution of individual Notch receptors.

  8. High levels of Notch signaling down-regulate Numb and Numblike

    NARCIS (Netherlands)

    Chapman, G.; Liu, L.; Sahlgren, C.; Dahlqvist, C.; Lendahl, U.

    2006-01-01

    Inhibition of Notch signaling by Numb is critical for many cell fate decisions. In this study, we demonstrate a more complex relationship between Notch and the two vertebrate Numb homologues Numb and Numblike. Although Numb and Numblike at low levels of Notch signaling negatively regulated Notch,

  9. Magnetoresistance effect in permalloy nanowires with various types of notches

    Directory of Open Access Journals (Sweden)

    Y. Gao

    2018-05-01

    Full Text Available Suppressing the stochastic domain wall (DW motion in magnetic nanowires is of great importance for designing DW-related spintronic devices. In this work, we have investigated the pinning/depinning processes of DWs in permalloy nanowires with three different types of notches by using longitudinal magnetoresistance (MR measurement. The averaged MR curves demonstrate that the stochastic DW depinning is suppressed partly or even completely by a transversely asymmetric notch. The single-shot MR curves show that how the resistance changes with the applied field also depends strongly on the notch type while the DW is pinned around the notch. In the case of two depinning fields, larger (smaller change of resistance always corresponds to larger (smaller depinning field, regardless of the notch type. These phenomena can be understood by that the spin structure around the notch changes differently with the notch type when the DW is traveling through the notch.

  10. Inhibitory role of Notch1 in calcific aortic valve disease.

    Directory of Open Access Journals (Sweden)

    Asha Acharya

    Full Text Available Aortic valve calcification is the most common form of valvular heart disease, but the mechanisms of calcific aortic valve disease (CAVD are unknown. NOTCH1 mutations are associated with aortic valve malformations and adult-onset calcification in families with inherited disease. The Notch signaling pathway is critical for multiple cell differentiation processes, but its role in the development of CAVD is not well understood. The aim of this study was to investigate the molecular changes that occur with inhibition of Notch signaling in the aortic valve. Notch signaling pathway members are expressed in adult aortic valve cusps, and examination of diseased human aortic valves revealed decreased expression of NOTCH1 in areas of calcium deposition. To identify downstream mediators of Notch1, we examined gene expression changes that occur with chemical inhibition of Notch signaling in rat aortic valve interstitial cells (AVICs. We found significant downregulation of Sox9 along with several cartilage-specific genes that were direct targets of the transcription factor, Sox9. Loss of Sox9 expression has been published to be associated with aortic valve calcification. Utilizing an in vitro porcine aortic valve calcification model system, inhibition of Notch activity resulted in accelerated calcification while stimulation of Notch signaling attenuated the calcific process. Finally, the addition of Sox9 was able to prevent the calcification of porcine AVICs that occurs with Notch inhibition. In conclusion, loss of Notch signaling contributes to aortic valve calcification via a Sox9-dependent mechanism.

  11. The pathological significance of Notch1 in oral squamous cell carcinoma.

    Science.gov (United States)

    Yoshida, Ryoji; Nagata, Masashi; Nakayama, Hideki; Niimori-Kita, Kanako; Hassan, Wael; Tanaka, Takuji; Shinohara, Masanori; Ito, Takaaki

    2013-10-01

    Notch signaling has been reported to be involved in several types of malignant tumors; however, the role and activation mechanism of Notch signaling in oral squamous cell carcinoma (OSCC) remains poorly characterized. The purpose of this study was to elucidate the pathological significance of Notch signaling and its activation mechanism in the development and progression of OSCC. In this study, we showed that the expression of Notch1 and intracellular Notch domain (NICD) are upregulated in OSCCs. In addition, Notch1 and NICD were found to be characteristically localized at the invasive tumor front. TNF-α, a major inflammatory cytokine, significantly activated Notch signaling in vitro. In a clinicopathological analysis, Notch1 expression correlated with both the T-stage and the clinical stage. Furthermore, loss of Notch1 expression correlated with the inhibition of cell proliferation and TNF-α-dependent invasiveness in an OSCC cell line. In addition, γ-secretase inhibitor (GSI) prevented cell proliferation and TNF-α-dependent invasion of OSCC cells in vitro. These results indicate that altered expression of Notch1 is associated with increased cancer progression and that Notch1 regulates the steps involved in cell metastasis in OSCC. Moreover, inactivating Notch signaling with GSI could therefore be a useful approach for treating patients with OSCC.

  12. Development of small punch tests for ductile-brittle transition temperature measurement of temper embrittled Ni-Cr steels

    International Nuclear Information System (INIS)

    Baik, J.M.; Kameda, J.; Buck, O.

    1983-01-01

    Small punch tests were developed to determine the ductile-brittle transition temperature of nickel-chromium (Ni-Cr) steels having various degrees of temper embrittlement and various microstructures. It was found that the small punch test clearly shows the ductile-brittle transition behavior of the temper-embrittled steels. The measured values were compared with those obtained from Charpy impact and uniaxial tensile tests. The effects of punch tip shape, a notch, and the strain rate on the ductile-brittle transition behavior were examined. It was found that the combined use of a notch, high strain rates, and a small punch tip strongly affects the ductile-brittle transition behavior. Considerable variations in the data were observed when the small punch tests were performed on coarse-grained steels. Several factors controlling embrittlement measurements of steels are discussed in terms of brittle fracture mechanisms

  13. Testing of irradiated and annealed 15H2MFA materials

    International Nuclear Information System (INIS)

    Gillemot, F.; Uri, G.

    1994-01-01

    A set of surveillance samples made from 15H2MFA material has been studied in the laboratory of AEKI. Miniature notched tensile specimens were cut from some remnants of irradiated and broke surveillance charpy remnants. The Absorbed Specific Fracture Energy (ASFE) was measured on the specimens. A cutting machine and testing technique were elaborated for the measurements. The second part of the Charpy remnants was annealed at 460 deg. C and 490 deg. C for 6-8 hours. The specimens were tested similarity and the results were compared. (author). 5 refs, 9 figs

  14. Temperature dependence of the dynamic fracture toughness of the alloy Incoloy 800 after cold work

    International Nuclear Information System (INIS)

    Krompholz, K.; Ullrich, G.

    1991-02-01

    Precracked charpy-V-notch specimens of the iron-nickel base alloy Incoloy 800 in the as-received condition and after cold work have been tested using an instrumented impact tester (hammer) in the temperature range 293 ≤ T/K ≤ 1223. The specific impact energies were determined by dial readings, from the integration of the load versus time and the load versus load point displacement diagrams; in all cases the agreement was excellent. The specific impact energies and the impulses are correlated with the test temperature and with the degree of cold work, respectively. The dynamic fracture toughness values were determined following the equivalent energy approach. In all cases a distinct decrease of the mechanical properties in the range between the as-received state and after 5 % cold work was found. The temperature behaviour of the impact energies clearly reveals an increase of its value between room temperature and 673 K. This increase is distinctly reduced after cold work. The dynamic fracture toughness decreases with increasing temperature. The fracture surfaces clearly show elasto-plastic fracture behaviour of the material in the temperature regime investigated. (author) 19 figs., 3 tabs., 7 refs

  15. Molecular Characterization of Notch1 Positive Progenitor Cells in the Developing Retina.

    Directory of Open Access Journals (Sweden)

    Galina Dvoriantchikova

    Full Text Available The oscillatory expression of Notch signaling in neural progenitors suggests that both repressors and activators of neural fate specification are expressed in the same progenitors. Since Notch1 regulates photoreceptor differentiation and contributes (together with Notch3 to ganglion cell fate specification, we hypothesized that genes encoding photoreceptor and ganglion cell fate activators would be highly expressed in Notch1 receptor-bearing (Notch1+ progenitors, directing these cells to differentiate into photoreceptors or into ganglion cells when Notch1 activity is diminished. To identify these genes, we used microarray analysis to study expression profiles of whole retinas and isolated from them Notch1+ cells at embryonic day 14 (E14 and postnatal day 0 (P0. To isolate Notch1+ cells, we utilized immunomagnetic cell separation. We also used Notch3 knockout (Notch3KO animals to evaluate the contribution of Notch3 signaling in ganglion cell differentiation. Hierarchical clustering of 6,301 differentially expressed genes showed that Notch1+ cells grouped near the same developmental stage retina cluster. At E14, we found higher expression of repressors (Notch1, Hes5 and activators (Dll3, Atoh7, Otx2 of neuronal differentiation in Notch1+ cells compared to whole retinal cell populations. At P0, Notch1, Hes5, and Dll1 expression was significantly higher in Notch1+ cells than in whole retinas. Otx2 expression was more than thirty times higher than Atoh7 expression in Notch1+ cells at P0. We also observed that retinas of wild type animals had only 14% (P < 0.05 more ganglion cells compared to Notch3KO mice. Since this number is relatively small and Notch1 has been shown to contribute to ganglion cell fate specification, we suggested that Notch1 signaling may play a more significant role in RGC development than the Notch3 signaling cascade. Finally, our findings suggest that Notch1+ progenitors--since they heavily express both pro-ganglion cell (Atoh7

  16. Notch-1 mediates hypoxia-induced angiogenesis in rheumatoid arthritis.

    Science.gov (United States)

    Gao, Wei; Sweeney, Catherine; Connolly, Mary; Kennedy, Aisling; Ng, Chin Teck; McCormick, Jennifer; Veale, Douglas J; Fearon, Ursula

    2012-07-01

    To examine the effect of hypoxia on Notch-1 signaling pathway components and angiogenesis in inflammatory arthritis. The expression and regulation of Notch-1, its ligand delta-like protein 4 (DLL-4) and downstream signaling components (hairy-related transcription factor 1 [HRT-1], HRT-2), and hypoxia-inducible factor 1α (HIF-1α) under normoxic and hypoxic conditions (1-3%) were assessed in synovial tissue specimens from patients with inflammatory arthritis and controls and in human dermal microvascular endothelial cells (HDMECs) by immunohistology, dual immunofluorescence staining (Notch-1/factor VIII), Western blotting, and real-time polymerase chain reaction. In vivo synovial tissue oxygen levels (tissue PO2) were measured under direct visualization at arthroscopy. HDMEC activation under hypoxic conditions in the presence of Notch-1 small interfering RNA (siRNA), the γ-secretase inhibitor DAPT, or dimethyloxalylglycine (DMOG) was assessed by Matrigel tube formation assay, migration assay, invasion assay, and matrix metalloproteinase 2 (MMP-2)/MMP-9 zymography. Expression of Notch-1, its ligand DLL-4, and HRT-1 was demonstrated in synovial tissue, with the strongest expression localized to perivascular/vascular regions. Localization of Notch-1 to synovial endothelium was confirmed by dual immunofluorescence staining. Notch-1 intracellular domain (NICD) expression was significantly higher in synovial tissue from patients with tissue PO2 of PO2 of >20 mm Hg (>3% O2). Exposure of HDMECs to 3% hypoxia induced HIF-1α and NICD protein expression and DLL-4, HRT-1, and HRT-2 messenger RNA expression. DMOG directly induced NICD expression, while Notch-1 siRNA inhibited hypoxia-induced HIF-1α expression, suggesting that Notch-1/HIF-1α signaling is bidirectional. Finally, 3% hypoxia-induced angiogenesis, endothelial cell migration, endothelial cell invasion, and proMMP-2 and proMMP-9 activities were inhibited by Notch-1 siRNA and/or the γ-secretase inhibitor DAPT. Our

  17. Evidence of non-canonical NOTCH signaling

    DEFF Research Database (Denmark)

    Traustadóttir, Gunnhildur Ásta; Jensen, Charlotte H; Thomassen, Mads

    2016-01-01

    Dlk1(+/+) and Dlk1(-/-) mouse tissues at E16.5, we demonstrated that several NOTCH signaling pathways indeed are affected by DLK1 during tissue development, and this was supported by a lower activation of NOTCH1 protein in Dlk1(+/+) embryos. Likewise, but using a distinct Dlk1-manipulated (si...

  18. Expresión de los genes Serrate1 y Notch1 durante el desarrollo del tercio medio facial del embrión de pollo.

    Directory of Open Access Journals (Sweden)

    Daniel Mauricio Meza Lasso

    2016-01-01

    Full Text Available La vía de señalización Notch se caracteriza por mediar la comunicación célula-célula, regulando diferentes procesos celulares como proliferación, apoptosis y definición del destino celular. Esta vía ha sido implicada en el desarrollo de estructuras craneofaciales como paladar, diente y bóveda craneal. El objetivo de esta investigación fue identificar los patrones de expresión de los genes componentes de la vía Notch, Serrate1 y Notch1, durante el desarrollo del tercio medio facial. Se utilizaron embriones de pollo (Gallus gallus seleccionados de acuerdo a los criterios de Hamilton y Hamburger y sobre los cuales se realizó hibridación in situ con ribosondas marcadas con Digoxigenina (DIG, para luego ser detectadas con anticuerpos Anti-Dig. Los resultados mostraron expresión de los genes evaluados, en las prominencias maxilares (pmx y frontonasal (pfn durante el desarrollo del tercio medio facial. Estos resultados sugieren una probable participación de la vía Notch a través de estos genes, en los diferentes procesos celulares que determinan la morfogénesis y el desarrollo del tercio medio facial.

  19. Notch and the awesome power of genetics.

    Science.gov (United States)

    Greenwald, Iva

    2012-07-01

    Notch is a receptor that mediates cell-cell interactions in animal development, and aberrations in Notch signal transduction can cause cancer and other human diseases. Here, I describe the major advances in the Notch field from the identification of the first mutant in Drosophila almost a century ago through the elucidation of the unusual mechanism of signal transduction a little over a decade ago. As an essay for the GENETICS Perspectives series, it is my personal and critical commentary as well as an historical account of discovery.

  20. Plane-stress fields for sharp notches in pressure-sensitive materials

    International Nuclear Information System (INIS)

    Al-Abduljabbar, Abdulhamid

    2003-01-01

    The effect of pressure sensitive yield on materials toughness can be determined by investigating stress fields around cracks and notches. In this work, fully-developed plastic stress fields around sharp wedge-shaped notches of perfectly-plastic pressure-sensitive materials are investigated for plane-stress case and Mode 1 loading condition. The pressure-sensitive yielding behavior is represented using the Drucker-Prager criterion. Using equilibrium equations, boundary conditions, and the yield criterion, closed-form expressions for stress fields are derived. The analysis covers the gradual change in the notch angle and compares it with the limiting case of a pure horizontal crack. Effects of notch geometry and pressure sensitivity on stress fields are examined by considering different specimen geometries, as well as different levels of pressure sensitivity. Results indicate that while the stress values directly ahead of the notch-tip are not affected, the extent of stress sector at notch front is reduced, thereby causing increase in the radial stress value around the notch. As the pressure sensitivity increases the reduction of the stress sector directly ahead of the notch tip is more evident. Also, for high pressure sensitivity values, introduction of the notch angle reduces the variation of the stress levels. Results are useful for design of structural components. (author)

  1. 3D analyses of the effect of weld orientation in Charpy specimens

    DEFF Research Database (Denmark)

    Tvergaard, Viggo; Needleman, A.

    2004-01-01

    . The onset of cleavage is taken to occur when the average of the maximum principal stress over a specified volume attains a critical value. The weld analyzed here is overmatched, so that the yield strength for the weld is larger than that of the base material. Analyses are carried out for specimens where...... the notch is cut parallel to the surface of the test piece, as well as more complex geometries where the notched surface of the specimen is rotated relative to the surface of the test piece. It is found that even for a homogeneous material the brittle-ductile transition can be much affected by three...... dimensional effects; for example, curvature of the deformed free surface gives rise to a stress increase that promotes cleavage. Furthermore, for the rotated specimens the weld geometry relative to the notched specimen surface is so complex that only a full 3D analysis is able to account for the interaction...

  2. Mechanical Properties of Laser Weldment of V-4Cr-4Ti Alloy

    International Nuclear Information System (INIS)

    Heo, Nam-Jin; Nagasaka, Takuya; Muroga, Takeo; Nishimura, Arata; Shinozaki, Kenji; Watanabe, Hideo

    2003-01-01

    The effect of the laser welding condition on properties of the weldment, such as bending, tensile and charpy impact properties were investigated in a V-4Cr-4Ti alloy (NIFS-HEAT- 2). The microstructural and microchemical development in the weldment was also investigated for mechanistic study of the impurity behavior during the welding. Increase in hardness occurred in the weld zone. The hardening was due to the dissolution of the large and small precipitates existed in the base metal before welding. The degree of hardening varied with a distance from the bead center. The absorption energy by the impact test increased with the decrease in the input power density during the laser welding. The impact absorption energy of the weld, which is similar to that of the base metal, was obtained by optimizing the welding condition

  3. Modifiers of notch transcriptional activity identified by genome-wide RNAi

    Directory of Open Access Journals (Sweden)

    Firnhaber Christopher B

    2010-10-01

    Full Text Available Abstract Background The Notch signaling pathway regulates a diverse array of developmental processes, and aberrant Notch signaling can lead to diseases, including cancer. To obtain a more comprehensive understanding of the genetic network that integrates into Notch signaling, we performed a genome-wide RNAi screen in Drosophila cell culture to identify genes that modify Notch-dependent transcription. Results Employing complementary data analyses, we found 399 putative modifiers: 189 promoting and 210 antagonizing Notch activated transcription. These modifiers included several known Notch interactors, validating the robustness of the assay. Many novel modifiers were also identified, covering a range of cellular localizations from the extracellular matrix to the nucleus, as well as a large number of proteins with unknown function. Chromatin-modifying proteins represent a major class of genes identified, including histone deacetylase and demethylase complex components and other chromatin modifying, remodeling and replacement factors. A protein-protein interaction map of the Notch-dependent transcription modifiers revealed that a large number of the identified proteins interact physically with these core chromatin components. Conclusions The genome-wide RNAi screen identified many genes that can modulate Notch transcriptional output. A protein interaction map of the identified genes highlighted a network of chromatin-modifying enzymes and remodelers that regulate Notch transcription. Our results open new avenues to explore the mechanisms of Notch signal regulation and the integration of this pathway into diverse cellular processes.

  4. On short cracks that depart from elastoplastic notch tips

    Directory of Open Access Journals (Sweden)

    Verônica Miquelin Machado

    2017-07-01

    Full Text Available The behavior of short cracks that depart from elastoplastic notch tips is modeled to estimate the stresses required to initiate and to propagate cracks in notched structural components, and to evaluate the size of tolerable crack-like defects under general loading conditions. This analysis can model both fatigue and environmentally assisted cracking problems; can evaluate notch sensitivity in both cases; and can as well be used to establish design or acceptance criteria for tolerable non-propagating crack-like defects in such cases. The growth of short cracks is assumed driven by the applied stresses and by the stress gradient ahead the notch tip, and supported by the material resistances to crack initiation and to long crack propagation by fatigue or EAC. In the elastoplastic case, the stress gradient ahead of the notch tip is quantified by a J-field to consider the short crack behavior. The tolerable short crack predictions made by this model are evaluated by suitable fatigue and EAC tests of notched specimens specially designed to start nonpropagating cracks from the notch tips, both under elastic and elastoplastic conditions.

  5. A new tensile impact test for the toughness characterization of sheet material

    Science.gov (United States)

    Könemann, Markus; Lenz, David; Brinnel, Victoria; Münstermann, Sebastian

    2018-05-01

    In the past, the selection of suitable steels has been carried out primarily based on the mechanical properties of different steels. One of these properties is the resistance against crack propagation. For many constructions, this value plays an important role, because it can compare the impact toughness of different steel grades easily and gives information about the loading capacity of the specific materials. For thin sheets, impact toughness properties were usually not considered. One of the reasons for this is that the Charpy-impact test is not applicable for sheets with thicknesses below 2 mm. For a long time, this was not relevant because conventional steels had a sufficient impact toughness in a wide temperature range. However, since new multiphase steel grades with improved mechanical property exploitations are available, it turned out that impact toughness properties need to be considered during the component design phase, as the activation of the cleavage fracture mechanism is observed under challenging loading conditions. Therefore, this work aims to provide a new and practical testing procedure for sheet material or thin walled structures. The new testing procedure is based on tensile tests conducted in an impact pendulum similar to the Charpy impact hammer. A new standard geometry is provided, which enables a comparison between different steels or steel grades. A connection to the conventional Charpy test is presented using a damage mechanics model, which predicts material failure with consideration of to the stress state at various temperatures. Different specimen geometries are analysed to cover manifold stress states. A special advantage of the damage mechanics model is also the possibility to predict the materials behaviour in the transition area. To verify the method a conventional steel was tested in Charpy tests as well as in the new tensile impact test.

  6. Aberrant Regulation of Notch3 Signaling Pathway in Polycystic Kidney Disease.

    Science.gov (United States)

    Idowu, Jessica; Home, Trisha; Patel, Nisha; Magenheimer, Brenda; Tran, Pamela V; Maser, Robin L; Ward, Christopher J; Calvet, James P; Wallace, Darren P; Sharma, Madhulika

    2018-02-20

    Polycystic kidney disease (PKD) is a genetic disorder characterized by fluid-filled cysts in the kidney and liver that ultimately leads to end-stage renal disease. Currently there is no globally approved therapy for PKD. The Notch signaling pathway regulates cellular processes such as proliferation and de-differentiation, which are cellular hallmarks of PKD. Thus we hypothesized that the Notch pathway plays a critical role in PKD. Evaluation of protein expression of Notch signaling components in kidneys of Autosomal Recessive PKD (ARPKD) and Autosomal Dominant PKD (ADPKD) mouse models and of ADPKD patients revealed that Notch pathway members, particularly Notch3, were consistently upregulated or activated in cyst-lining epithelial cells. Notch3 expression correlated with rapidly growing cysts and co-localized with the proliferation marker, PCNA. Importantly, Notch inhibition significantly decreased forskolin-induced Notch3 activation and proliferation of primary human ADPKD cells, and significantly reduced cyst formation and growth of human ADPKD cells cultured in collagen gels. Thus our data indicate that Notch3 is aberrantly activated and facilitates epithelial cell proliferation in PKD, and that inhibition of Notch signaling may prevent cyst formation and growth.

  7. Proteolytic regulation of Notch1 receptor activity in cancer

    NARCIS (Netherlands)

    van Tetering, Geert

    2011-01-01

    The Notch receptor is part of a highly conserved signaling pathway essential in development and disease in embryos and adults. Notch proteins coordinate cell-cell communication through receptor-ligand interactions between adjacent cells. First Notch is cleaved in the Golgi by furin at Site-1 (S1)

  8. Significance of a notch in the otoacoustic emission stimulus spectrum.

    Science.gov (United States)

    Grenner, J

    2012-09-01

    To explain a clinical observation: a notch in the stimulus spectrum during transient evoked otoacoustic emission measurement in ears with secretory otitis media. The effects of tympanic under-pressure were investigated using a pressure chamber. A model of the ear canal was also studied. Tympanic membrane reflectance increased as a consequence of increased stiffness, causing a notch in the stimulus spectrum. In an adult, the notch could be clearly distinguished at an under-pressure of approximately -185 daPa. The sound frequency of the notch corresponded to a wavelength four times the ear canal length. The ear canal of infants was too short to cause a notch within the displayed frequency range. The notch was demonstrated using both Otodynamics and Madsen equipment. A notch in the otoacoustic emission stimulus spectrum can be caused by increased stiffness of the tympanic membrane, raising suspicion of low middle-ear pressure or secretory otitis media. This finding is not applicable to infants.

  9. Notch3 marks clonogenic mammary luminal progenitor cells in vivo.

    Science.gov (United States)

    Lafkas, Daniel; Rodilla, Veronica; Huyghe, Mathilde; Mourao, Larissa; Kiaris, Hippokratis; Fre, Silvia

    2013-10-14

    The identity of mammary stem and progenitor cells remains poorly understood, mainly as a result of the lack of robust markers. The Notch signaling pathway has been implicated in mammary gland development as well as in tumorigenesis in this tissue. Elevated expression of the Notch3 receptor has been correlated to the highly aggressive "triple negative" human breast cancer. However, the specific cells expressing this Notch paralogue in the mammary gland remain unknown. Using a conditionally inducible Notch3-CreERT2(SAT) transgenic mouse, we genetically marked Notch3-expressing cells throughout mammary gland development and followed their lineage in vivo. We demonstrate that Notch3 is expressed in a highly clonogenic and transiently quiescent luminal progenitor population that gives rise to a ductal lineage. These cells are capable of surviving multiple successive pregnancies, suggesting a capacity to self-renew. Our results also uncover a role for the Notch3 receptor in restricting the proliferation and consequent clonal expansion of these cells.

  10. Effect of microstructure on the susceptibility of a 533 steel to temper embrittlement

    International Nuclear Information System (INIS)

    Raoul, S.; Marini, B.; Pineau, A.

    1998-01-01

    In ferritic steels, brittle fracture usually occurs at low temperature by cleavage. However the segregation of impurities (P, As, Sn etc..) along prior γ grain boundaries can change the brittle fracture mode from transgranular to intergranular. In quenched and tempered steels, this segregation is associated with what is called the temper-embrittlement phenomenon. The main objective of the present study is to investigate the influence of the as-quenched microstructure (lower bainite or martensite) on the susceptibility of a low alloy steel (A533 cl.1) to temper-embrittlement. Dilatometric tests were performed to determine the continous-cooling-transformation (CCT) diagram of the material and to measure the critical cooling rate (V c ) for a martensitic quench. Then subsized Charpy V-notched specimens were given various cooling rates from the austenitization temperature to obtain a wide range of as-quenched microstructures, including martensite and bainite. These specimens were subsequently given a heat treatment to develop temper embrittlement and tested to measure the V-notch fracture toughness at -50 C. The fracture surfaces were examined by SEM. It is shown that martensitic microstructures are more susceptible to intergranular embrittlement than bainitic microstructures. These observed microstructural influences are briefly discussed. (orig.)

  11. Analysis of Intergranular Precipitation in Isothermally Aged Nitrogen-Containing Austenitic Stainless Steels by an Electrochemical Method and Its Relation to Cryogenic Toughness

    Directory of Open Access Journals (Sweden)

    Maribel L. Saucedo-Muñoz

    2011-01-01

    Full Text Available The precipitation process in two N-containing austenitic stainless steels, aged at temperatures between 873 and 1173 K for times from 10 to 1000 min, was analyzed by an electrochemical method based on the anodic polarization test with an electrolyte of 1 N KOH solution. The anodic polarization curves showed the following intergranular precipitation sequence: austenite → austenite + Cr23C6→ austenite + Cr23C6 + Cr2N. Besides, the fastest precipitation kinetics was detected in the aged steel with the highest content of nitrogen and carbon due to its higher driving force for precipitation. The higher the aging temperature, the higher volume fraction of precipitates. The precipitation fraction can be associated with the current density of the dissolution peaks of each phase. The Charpy-V-Notch impact energy of the aged specimens decreased with the increase in the volume fraction of precipitates.

  12. Study on aging embrittlement of 17-4PH martensite stainless steel at 350 degree C

    International Nuclear Information System (INIS)

    Wang Jun; Shen Baoluo

    2005-01-01

    The transformation of microstructure and hardness with the extension of aging time on the 17-4PH Martensite stainless steel at 350 degree C is studied, and the change of dynamic fracture toughness and fractography of the stainless steel for various holding time at this temperature are also studied by instrumental impact test and scanning electron microscope. The results indicate that the crack initiation energy (E i ), crack propagation energy (E p ), absorbed-in-fracture energy (E t ) and dynamic fracture toughness (K 1d ) of this type of alloy Charpy v-notch sample is decreased with the continuation of time at 350 degree C. It means that the toughness of the alloy is degraded, and the hardness of the steel is ascended when aging time is expanded and reaches the maximum at 9000 h. The fractography of this steel changes from dimple fracture into cleavage fracture and inter-granular rapture. (authors)

  13. Resistance spot weldability of 11Cr–ferritic/martensitic steel sheets

    International Nuclear Information System (INIS)

    Uwaba, Tomoyuki; Yano, Yasuhide; Ito, Masahiro

    2012-01-01

    Resistance spot welding of 11Cr–0.4Mo–2W, V, Nb ferritic/martensitic steel sheets with different thicknesses was examined to develop a manufacturing technology for a fast reactor fuel subassembly with an inner duct structure. In the spot welding, welding current, electrode force, welding time and holding time were varied as welding parameters to investigate the appropriate welding conditions. Welding conditions under which spot weld joints did not have either crack or void defects in the nugget could be found when the electrode force was increased to 9.8 kN. It was also found that the electrode cap with a longer tip end length was effective for preventing weld defect formations. Strength of the spot welded joint was characterized from micro hardness and shear tension tests. In addition, the ductile-to-brittle transition temperature of the spot welded joint was measured by Charpy impact tests with specimens that had notches in the welded zone.

  14. Advanced-gas-cooled-nuclear-reactor materials evaluation and development program. Volume 1.Final report, September 23, 1976-September 30, 1982

    International Nuclear Information System (INIS)

    Kimball, O.F.

    1983-01-01

    Included in this report is a discussion of the materials selected for the screening phase and more intensive screening phase test programs and the systems and components for which they are candidate materials. Thirty-one (31) commercially available alloy and alloy/coating materials and ten (10) experimental alloys were evaluated in the program. The experimental test facilities developed as part of this program are discussed and experimental testing procedures are summarized. The results of the initial screening test programs are presented. This includes creep testing results and metallographic analyses of candidate materials exposed to simulated HTGR helium and air under stress at temperatures of 750 0 , 850 0 , 950 0 , or 1050 0 C (1382 0 , 1562 0 , 1742 0 , or 1922 0 F) for exposure times to 10,000 hours. Metallographic analyses, weight change and carbon analyses results, and post exposure room temperature tensile and Charpy V-notch impact test results are presented for candidate materials exposed unstressed under the conditions stated above

  15. Evaluating mechanical properties of hybrid laser arc girth welds

    Energy Technology Data Exchange (ETDEWEB)

    Pussegoda, L. N.; Begg, D.; Holdstock, R.; Jodoin, A. [BMT Fleet Technology Ltd Techonology, Kanata, ON, (Canada); Ligh, K.; Rondeau, D. [Appliead Thermal Sciences Inc., Sanford, ME, (United States); Hansen, E. [ESAB, Florence, SC, (United States)

    2010-07-01

    Hybrid laser arc welding (HLAW) is a promising new process for making girth welds on steel pipelines. This study investigated the mechanical properties of overmatched X80 and X100 pipeline steel girth welds made using the HLAW process. The testing of this process was conducted on NPS36 pipes of 10.4 mm and 14.3 mm thickness, respectively. Various weld positions were produced on X80 and X100 pipes. Laser inspection data were collected during the whole welding process. Also standard tests for girth welds, Charpy V-notch impact tests, CTOD tests, all weld metal (AWM) tension tests, were carried out. The results showed that the fracture transition temperature is higher at the 3 and 9 o'clock positions than at the 9 and 12 o'clock positions. The effect of clock position on fracture toughness is currently being explored; a modified CTOD has been developed to reduce the possibility of crack deviation.

  16. The importance of Notch signaling in peripheral T-cell lymphomas

    DEFF Research Database (Denmark)

    Kamstrup, Maria Rørbæk; Biskup, Edyta; Gjerdrum, Lise Mette Rahbek

    2014-01-01

    Peripheral T-cell lymphomas (PTLs) represent an area of high medical need. Previously, we demonstrated high expression of Notch, a known oncogene, in primary cutaneous anaplastic large cell lymphoma (ALCL). In this study, we performed immunohistochemical staining for Notch1 in lymph nodes from PTL...... cases) (p > 0.05). In the ALK+ ALCL cell line, Karpas-299, pharmacological inhibition of Notch with γ-secretase inhibitor (GSI) I was far more potent than with GSI IX, XX and XXI with regard to cell viability and apoptosis. In conclusion, PTL tumor cells have prominent Notch1 expression and treatment...... with Notch inhibitors has cytotoxic effects....

  17. High NOTCH activity induces radiation resistance in non small cell lung cancer

    International Nuclear Information System (INIS)

    Theys, Jan; Yahyanejad, Sanaz; Habets, Roger; Span, Paul; Dubois, Ludwig; Paesmans, Kim; Kattenbeld, Bo; Cleutjens, Jack; Groot, Arjan J.; Schuurbiers, Olga C.J.; Lambin, Philippe; Bussink, Jan; Vooijs, Marc

    2013-01-01

    Background and purpose: Patients with advanced NSCLC have survival rates <15%. The NOTCH pathway plays an important role during lung development and physiology but is often deregulated in lung cancer, making it a potential therapeutic target. We investigated NOTCH signaling in NSCLC and hypothesized that high NOTCH activity contributes to radiation resistance. Materials and methods: NOTCH signaling in NSCLC patient samples was investigated using quantitative RT-PCR. H460 NSCLC cells with either high or blocked NOTCH activity were generated and their radiation sensitivity monitored using clonogenic assays. In vivo, xenograft tumors were irradiated and response assessed using growth delay. Microenvironmental parameters were analyzed by immunohistochemistry. Results: Patients with high NOTCH activity in tumors showed significantly worse disease-free survival. In vitro, NOTCH activity did not affect the proliferation or intrinsic radiosensitivity of NSCLC cells. In contrast, xenografts with blocked NOTCH activity grew slower than wild type tumors. Tumors with high NOTCH activity grew significantly faster, were more hypoxic and showed a radioresistant phenotype. Conclusions: We demonstrate an important role for NOTCH in tumor growth and correlate high NOTCH activity with poor prognosis and radioresistance. Blocking NOTCH activity in NSCLC might be a promising intervention to improve outcome after radiotherapy

  18. Notched audiograms and noise exposure history in older adults.

    Science.gov (United States)

    Nondahl, David M; Shi, Xiaoyu; Cruickshanks, Karen J; Dalton, Dayna S; Tweed, Ted S; Wiley, Terry L; Carmichael, Lakeesha L

    2009-12-01

    Using data from a population-based cohort study, we compared four published algorithms for identifying notched audiograms and compared their resulting classifications with noise exposure history. Four algorithms: (1) , (2) , (3) , and (4) were used to identify notched audiograms. Audiometric evaluations were collected as a part of the 10-yr follow-up examinations of the Epidemiology of Hearing Loss Study, in Beaver Dam, WI (2003-2005, N = 2395). Detailed noise exposure histories were collected by interview at the baseline examination (1993-1995) and updated at subsequent visits. An extensive history of occupational noise exposure, participation in noisy hobbies, and firearm usage was used to evaluate consistency of the notch classifications with the history of noise exposure. The prevalence of notched audiograms varied greatly by definition (31.7, 25.9, 47.2, and 11.7% for methods 1, 2, 3, and 4, respectively). In this cohort, a history of noise exposure was common (56.2% for occupational noise, 71.7% for noisy hobbies, 13.4% for firearms, and 81.2% for any of these three sources). Among participants with a notched audiogram, almost one-third did not have a history of occupational noise exposure (31.4, 33.0, 32.5, and 28.1% for methods 1, 2, 3, and 4, respectively), and approximately 11% did not have a history of exposure to any of the three sources of noise (11.5, 13.6, 10.3, and 7.6%). Discordance was greater in women than in men. These results suggest that there is a poor agreement across existing algorithms for audiometric notches. In addition, notches can occur in the absence of a positive noise history. In the absence of an objective consensus definition of a notched audiogram and in light of the degree of discordance in women between noise history and notches by each of these algorithms, researchers should be cautious about classifying noise-induced hearing loss by notched audiograms.

  19. Inhibition of Notch1 increases paclitaxel sensitivity to human breast cancer

    Institute of Scientific and Technical Information of China (English)

    Zhao Li; Ma Yongjie; Gu Feng; Fu Li

    2014-01-01

    Background Paclitaxel (PAC) is the first-line chemotherapy drug for most breast cancer patients,but clinical studies showed that some breast cancer patients were insensitive to PAC,which led to chemotherapy failure.It was reported that Notch1 signaling participated in drug resistance of breast cancer.Here,we show whether Notch1 expression is related to PAC sensitivity of breast cancer.Methods We employed Notch1 siRNA and Notch1 inhibitor,N-[N-(3,5-difluorophenacetyl)-1-alanyl]-S-phenylglycine t-butylester (DAPT),to down regulate Notch1 expression in human breast cancer cells MDA-MB-231,and detected the inhibition effect by Western blotting and reverse trans cription-polymerase chain reaction,respectively.After 24 hours exposure to different concentration of PAC (0,1,5,10,15,20,and 25 μg/ml),the viability of the control group and experimental group cells was tested by MTT.We also examined the expression of Notch1 in PAC sensitive and nonsensitive breast cancer patients,respectively by immunohistochemistry (IHC).The PAC sensitivity of breast cancer patients were identified by collagen gel droplet embedded culture-drug sensitivity test (CD-DST).Results Down regulation of Notch1 expression by Notch1siRNA interference or Notch1 inhibitor increased the PAC sensitivity in MDA-MB-231 cells (P <0.05).Also,the expression of Notch1 in PAC sensitive patients was much lower than that of PAC non-sensitive patients (P <0.01).Conclusion Notch1 expression has an effect on PAC sensitivity in breast cancer patients,and the inhibition of Notch1 increases paclitaxel sensitivity to human breast cancer.

  20. NOTCH1 Is Aberrantly Activated in Chronic Lymphocytic Leukemia Hematopoietic Stem Cells

    Directory of Open Access Journals (Sweden)

    Mauro Di Ianni

    2018-04-01

    Full Text Available To investigate chronic lymphocytic leukemia (CLL-initiating cells, we assessed NOTCH1 mutation/expression in hematopoietic stem cells (HSCs. In NOTCH1-mutated CLL, we detected subclonal mutations in 57% CD34+/CD38− HSCs. NOTCH1 mutation was present in 66% CD34+/CD38+ progenitor cells displaying an increased mutational burden compared to HSCs. Flow cytometric analysis revealed significantly higher NOTCH1 activation in CD34+/CD38− and CD34+/CD38+ cells from CLL patients, regardless NOTCH1 mutation compared to healthy donors. Activated NOTCH1 resulted in overexpression of the NOTCH1 target c-MYC. We conclude that activated NOTCH1 is an early event in CLL that may contribute to aberrant HSCs in this disease.

  1. NOTCH1 Is Aberrantly Activated in Chronic Lymphocytic Leukemia Hematopoietic Stem Cells.

    Science.gov (United States)

    Di Ianni, Mauro; Baldoni, Stefano; Del Papa, Beatrice; Aureli, Patrizia; Dorillo, Erica; De Falco, Filomena; Albi, Elisa; Varasano, Emanuela; Di Tommaso, Ambra; Giancola, Raffaella; Accorsi, Patrizia; Rotta, Gianluca; Rompietti, Chiara; Silva Barcelos, Estevão Carlos; Campese, Antonio Francesco; Di Bartolomeo, Paolo; Screpanti, Isabella; Rosati, Emanuela; Falzetti, Franca; Sportoletti, Paolo

    2018-01-01

    To investigate chronic lymphocytic leukemia (CLL)-initiating cells, we assessed NOTCH1 mutation/expression in hematopoietic stem cells (HSCs). In NOTCH1- mutated CLL, we detected subclonal mutations in 57% CD34+/CD38- HSCs. NOTCH1 mutation was present in 66% CD34+/CD38+ progenitor cells displaying an increased mutational burden compared to HSCs. Flow cytometric analysis revealed significantly higher NOTCH1 activation in CD34+/CD38- and CD34+/CD38+ cells from CLL patients, regardless NOTCH1 mutation compared to healthy donors. Activated NOTCH1 resulted in overexpression of the NOTCH1 target c-MYC. We conclude that activated NOTCH1 is an early event in CLL that may contribute to aberrant HSCs in this disease.

  2. Static and Fatigue Behavior Investigation of Artificial Notched Steel Reinforcement

    Directory of Open Access Journals (Sweden)

    Yafei Ma

    2017-05-01

    Full Text Available Pitting corrosion is one of the most common forms of localized corrosion. Corrosion pit results in a stress concentration and fatigue cracks usually initiate and propagate from these corrosion pits. Aging structures may fracture when the fatigue crack reaches a critical size. This paper experimentally simulates the effects of pitting morphologies on the static and fatigue behavior of steel bars. Four artificial notch shapes are considered: radial ellipse, axial ellipse, triangle and length-variable triangle. Each shape notch includes six sizes to simulate a variety of pitting corrosion morphologies. The stress-strain curves of steel bars with different notch shape and depth are obtained based on static tensile testing, and the stress concentration coefficients for various conditions are determined. It was determined that the triangular notch has the highest stress concentration coefficient, followed by length-variable triangle, radial ellipse and axial ellipse shaped notches. Subsequently, the effects of notch depth and notch aspect ratios on the fatigue life under three stress levels are investigated by fatigue testing, and the equations for stress range-fatigue life-notch depth are obtained. Several conclusions are drawn based on the proposed study. The established relationships provide an experimental reference for evaluating the fatigue life of concrete bridges.

  3. Identification of a Paralog-Specific Notch1 Intracellular Domain Degron

    Directory of Open Access Journals (Sweden)

    Matthew R. Broadus

    2016-05-01

    Full Text Available Upon Notch pathway activation, the receptor is cleaved to release the Notch intracellular domain (NICD, which translocates to the nucleus to activate gene transcription. Using Xenopus egg extracts, we have identified a Notch1-specific destruction signal (N1-Box. We show that mutations in the N1-Box inhibit NICD1 degradation and that the N1-Box is transferable for the promotion of degradation of heterologous proteins in Xenopus egg extracts and in cultured human cells. Mutation of the N1-Box enhances Notch1 activity in cultured human cells and zebrafish embryos. Human cancer mutations within the N1-Box enhance Notch1 signaling in transgenic zebrafish, highlighting the physiological relevance of this destruction signal. We find that binding of the Notch nuclear factor, CSL, to the N1-Box blocks NICD1 turnover. Our studies reveal a mechanism by which degradation of NICD1 is regulated by the N1-Box to minimize stochastic flux and to establish a threshold for Notch1 pathway activation.

  4. NOTCH2 signaling confers immature morphology and aggressiveness in human hepatocellular carcinoma cells.

    Science.gov (United States)

    Hayashi, Yoshihiro; Osanai, Makoto; Lee, Gang-Hong

    2015-10-01

    The NOTCH family of membranous receptors plays key roles during development and carcinogenesis. Since NOTCH2, yet not NOTCH1 has been shown essential for murine hepatogenesis, NOTCH2 rather than NOTCH1 may be more relevant to human hepatocarcinogenesis; however, no previous studies have supported this hypothesis. We therefore assessed the role of NOTCH2 in human hepatocellular carcinoma (HCC) by immunohistochemistry and cell culture. Immunohistochemically, 19% of primary HCCs showed nuclear staining for NOTCH2, indicating activated NOTCH2 signaling. NOTCH2-positive HCCs were on average in more advanced clinical stages, and exhibited more immature cellular morphology, i.e. higher nuclear-cytoplasmic ratios and nuclear densities. Such features were not evident in NOTCH1‑positive HCCs. In human HCC cell lines, abundant NOTCH2 expression was associated with anaplasia, represented by loss of E-cadherin. When NOTCH2 signaling was stably downregulated in HLF cells, an anaplastic HCC cell line, the cells were attenuated in potential for in vitro invasiveness and migration, as well as in vivo tumorigenicity accompanied by histological maturation. Generally, inverse results were obtained for a differentiated HCC cell line, Huh7, manipulated to overexpress activated NOTCH2. These findings suggested that the NOTCH2 signaling may confer aggressive behavior and immature morphology in human HCC cells.

  5. In vivo analysis of the Notch receptor S1 cleavage.

    Directory of Open Access Journals (Sweden)

    Robert J Lake

    2009-08-01

    Full Text Available A ligand-independent cleavage (S1 in the extracellular domain of the mammalian Notch receptor results in what is considered to be the canonical heterodimeric form of Notch on the cell surface. The in vivo consequences and significance of this cleavage on Drosophila Notch signaling remain unclear and contradictory. We determined the cleavage site in Drosophila and examined its in vivo function by a transgenic analysis of receptors that cannot be cleaved. Our results demonstrate a correlation between loss of cleavage and loss of in vivo function of the Notch receptor, supporting the notion that S1 cleavage is an in vivo mechanism of Notch signal control.

  6. The functional role of Notch signaling in human gliomas

    DEFF Research Database (Denmark)

    Stockhausen, Marie-Thérése; Kristoffersen, Karina; Poulsen, Hans Skovgaard

    2010-01-01

    have been referred to as brain cancer stem cells (bCSC), as they share similarities to normal neural stem cells in the brain. The Notch signaling pathway is involved in cell fate decisions throughout normal development and in stem cell proliferation and maintenance. The role of Notch in cancer is now...... firmly established, and recent data implicate a role for Notch signaling also in gliomas and bCSC. In this review, we explore the role of the Notch signaling pathway in gliomas with emphasis on its role in normal brain development and its interplay with pathways and processes that are characteristic...

  7. Hyper-activation of Notch3 amplifies the proliferative potential of rhabdomyosarcoma cells.

    Directory of Open Access Journals (Sweden)

    Maria De Salvo

    Full Text Available Rhabdomyosarcoma (RMS is a pediatric myogenic-derived soft tissue sarcoma that includes two major histopathological subtypes: embryonal and alveolar. The majority of alveolar RMS expresses PAX3-FOXO1 fusion oncoprotein, associated with the worst prognosis. RMS cells show myogenic markers expression but are unable to terminally differentiate. The Notch signaling pathway is a master player during myogenesis, with Notch1 activation sustaining myoblast expansion and Notch3 activation inhibiting myoblast fusion and differentiation. Accordingly, Notch1 signaling is up-regulated and activated in embryonal RMS samples and supports the proliferation of tumor cells. However, it is unable to control their differentiation properties. We previously reported that Notch3 is activated in RMS cell lines, of both alveolar and embryonal subtype, and acts by inhibiting differentiation. Moreover, Notch3 depletion reduces PAX3-FOXO1 alveolar RMS tumor growth in vivo. However, whether Notch3 activation also sustains the proliferation of RMS cells remained unclear. To address this question, we forced the expression of the activated form of Notch3, Notch3IC, in the RH30 and RH41 PAX3-FOXO1-positive alveolar and in the RD embryonal RMS cell lines and studied the proliferation of these cells. We show that, in all three cell lines tested, Notch3IC over-expression stimulates in vitro cell proliferation and prevents the effects of pharmacological Notch inhibition. Furthermore, Notch3IC further increases RH30 cell growth in vivo. Interestingly, knockdown of Notch canonical ligands JAG1 or DLL1 in RMS cell lines decreases Notch3 activity and reduces cell proliferation. Finally, the expression of Notch3IC and its target gene HES1 correlates with that of the proliferative marker Ki67 in a small cohort of primary PAX-FOXO1 alveolar RMS samples. These results strongly suggest that high levels of Notch3 activation increase the proliferative potential of RMS cells.

  8. Oncogenic programmes and Notch activity: an 'organized crime'?

    Science.gov (United States)

    Dominguez, Maria

    2014-04-01

    The inappropriate Notch signalling can influence virtually all aspect of cancer, including tumour-cell growth, survival, apoptosis, angiogenesis, invasion and metastasis, although it does not do this alone. Hence, elucidating the partners of Notch that are active in cancer is now the focus of much intense research activity. The genetic toolkits available, coupled to the small size and short life of the fruit fly Drosophila melanogaster, makes this an inexpensive and effective animal model, suited to large-scale cancer gene discovery studies. The fly eye is not only a non-vital organ but its stereotyped size and disposition also means it is easy to screen for mutations that cause tumours and metastases and provides ample opportunities to test cancer theories and to unravel unanticipated nexus between Notch and other cancer genes, or to discover unforeseen Notch's partners in cancer. These studies suggest that Notch's oncogenic capacity is brought about not simply by increasing signal strength but through partnerships, whereby oncogenes gain more by cooperating than acting individually, as in a ring 'organized crime'. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. PI3K/AKT signaling inhibits NOTCH1 lysosome-mediated degradation.

    Science.gov (United States)

    Platonova, Natalia; Manzo, Teresa; Mirandola, Leonardo; Colombo, Michela; Calzavara, Elisabetta; Vigolo, Emilia; Cermisoni, Greta Chiara; De Simone, Daria; Garavelli, Silvia; Cecchinato, Valentina; Lazzari, Elisa; Neri, Antonino; Chiaramonte, Raffaella

    2015-06-06

    The pathways of NOTCH and PI3K/AKT are dysregulated in about 60% and 48% of T-cell acute lymphoblastic leukemia (T-ALL) patients, respectively. In this context, they interact and cooperate in controlling tumor cell biology. Here, we propose a novel mechanism by which the PI3K/AKT pathway regulates NOTCH1 in T-ALL, starting from the evidence that the inhibition of PI3K/AKT signaling induced by treatment with LY294002 or transient transfection with a dominant negative AKT mutant downregulates NOTCH1 protein levels and activity, without affecting NOTCH1 transcription. We showed that the withdrawal of PI3K/AKT signaling was associated to NOTCH1 phosphorylation in tyrosine residues and monoubiquitination of NOTCH1 detected by Ubiquitin capture assay. Co-immunoprecipitation assay and colocalization analysis further showed that the E3 ubiquitin ligase c-Cbl interacts and monoubiquitinates NOTCH1, activating its lysosomal degradation. These results suggest that the degradation of NOTCH1 could represent a mechanism of control by which NOTCH1 receptors are actively removed from the cell surface. This mechanism is finely regulated by the PI3K/AKT pathway in physiological conditions. In pathological conditions characterized by PI3K/AKT hyperactivation, such as T-ALL, the excessive AKT signaling could lead to NOTCH1 signaling dysregulation. Therefore, a therapeutic strategy directed to PI3K/AKT in T-ALL could contemporaneously inhibit the dysregulated NOTCH1 signaling. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  10. The histone deacetylase HDAC1 positively regulates Notch signaling during Drosophila wing development

    Directory of Open Access Journals (Sweden)

    Zehua Wang

    2018-02-01

    Full Text Available The Notch signaling pathway is highly conserved across different animal species and plays crucial roles in development and physiology. Regulation of Notch signaling occurs at multiple levels in different tissues and cell types. Here, we show that the histone deacetylase HDAC1 acts as a positive regulator of Notch signaling during Drosophila wing development. Depletion of HDAC1 causes wing notches on the margin of adult wing. Consistently, the expression of Notch target genes is reduced in the absence of HDAC1 during wing margin formation. We further provide evidence that HDAC1 acts upstream of Notch activation. Mechanistically, we show that HDAC1 regulates Notch protein levels by promoting Notch transcription. Consistent with this, the HDAC1-associated transcriptional co-repressor Atrophin (Atro is also required for transcriptional activation of Notch in the wing disc. In summary, our results demonstrate that HDAC1 positively regulates Notch signaling and reveal a previously unidentified function of HDAC1 in Notch signaling.

  11. A three-dimensional analysis of the sigmoid notch

    Directory of Open Access Journals (Sweden)

    Evan D. Collins

    2011-12-01

    Full Text Available Fractures of the distal radius are among the most common injuries of the upper extremity, though treatment has traditionally focused on restoration of the radiocarpal joint and late sequelae may persist. X-ray imaging underestimates sigmoid notch involvement following distal radius fractures. No classification system exists for disruption patterns of the sigmoid notch of the radius associated with distal radius fractures. This study quantifies the anatomy of the sigmoid notch and identifies the landmarks of the articular surface and proximal boundaries of the distal radioulnar joint (DRUJ capsule. Computed tomography scans of freshly frozen cadaveric hands were used - followed by dissection, and three-dimensional reconstruction of the distal radius and sigmoid notch. The sigmoid notch surface was divided into two surfaces and measured. The Anterior Posterior (AP and Proximal Distal (PD widths of the articulating surface were reviewed, along with the radius of curvature, version angle and depth. The study showed that the sigmoid notch is flatter than previously believed - and only the distal 69% of its surface is covered by cartilage. On average, it has about nine degrees of retroversion, and its average inclination is almost parallel to the anatomical axis of the radius. Clinical implications exist for evaluation of the DRUJ involvement in distal radius fractures or degenerative diseases and for future development and evaluation of hemiarthroplasty replacement of the distal radius.

  12. Far infrared promotes wound healing through activation of Notch1 signaling.

    Science.gov (United States)

    Hsu, Yung-Ho; Lin, Yuan-Feng; Chen, Cheng-Hsien; Chiu, Yu-Jhe; Chiu, Hui-Wen

    2017-11-01

    The Notch signaling pathway is critically involved in cell proliferation, differentiation, development, and homeostasis. Far infrared (FIR) has an effect that promotes wound healing. However, the underlying molecular mechanisms are unclear. In the present study, we employed in vivo and HaCaT (a human skin keratinocyte cell line) models to elucidate the role of Notch1 signaling in FIR-promoted wound healing. We found that FIR enhanced keratinocyte migration and proliferation. FIR induced the Notch1 signaling pathway in HaCaT cells and in a microarray dataset from the Gene Expression Omnibus database. We next determined the mRNA levels of NOTCH1 in paired normal and wound skin tissues derived from clinical patients using the microarray dataset and Ingenuity Pathway Analysis software. The result indicated that the Notch1/Twist1 axis plays important roles in wound healing and tissue repair. In addition, inhibiting Notch1 signaling decreased the FIR-enhanced proliferation and migration. In a full-thickness wound model in rats, the wounds healed more rapidly and the scar size was smaller in the FIR group than in the light group. Moreover, FIR could increase Notch1 and Delta1 in skin tissues. The activation of Notch1 signaling may be considered as a possible mechanism for the promoting effect of FIR on wound healing. FIR stimulates keratinocyte migration and proliferation. Notch1 in keratinocytes has an essential role in FIR-induced migration and proliferation. NOTCH1 promotes TWIST1-mediated gene expression to assist wound healing. FIR might promote skin wound healing in a rat model. FIR stimulates keratinocyte migration and proliferation. Notch1 in keratinocytes has an essential role in FIR-induced migration and proliferation. NOTCH1 promotes TWIST1-mediated gene expression to assist wound healing. FIR might promote skin wound healing in a rat model.

  13. Mandibular Ramus Notching As a Tool for Sexual Dimorphism

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    Bibhuti Bhusana Panda

    2016-02-01

    Full Text Available Sex determination from a single or a part of bone is always difficult in absence of other bones of the same individual. The current study is an attempt to know the sex of an individual from the study of posterior ramus of mandible. The study was done from December, 2014 to August, 2015 in various Medical Colleges of the state of Odisha, India with the use of morbid anatomical specimen of mandibles and simple measuring instruments. The posterior ramus of adult mandibles were studied for presence or absence of any notching and if present its position in relation to occlusal plane. The study resulted, that there was a role of notch position in sex determination. The presence or absence of the notch though was not a consistent finding of all the mandibles. Males had frequent notching at the level of occlusal plane (P< 0.01 and females had frequent notching above the occlusal plane (P < 0.01. Notch present below the occlusal plane had no relation with sex. Accuracy of sexing mandible from the posterior ramus notch position was 61%, which was more for males (68.57% as compared to females (43.33%. So the posterior ramus of mandible could be considered for determination of sex of mandible but this should not be the sole criteria and should be correlated with the other standard criteria.

  14. Notch signaling inhibitor DAPT provides protection against acute craniocerebral injury.

    Directory of Open Access Journals (Sweden)

    Hong-Mei Zhang

    Full Text Available Notch signaling pathway is involved in many physiological and pathological processes. The γ-secretase inhibitor DAPT inhibits Notch signaling pathway and promotes nerve regeneration after cerebral ischemia. However, neuroprotective effects of DAPT against acute craniocerebral injury remain unclear. In this study, we established rat model of acute craniocerebral injury, and found that with the increase of damage grade, the expression of Notch and downstream protein Hes1 and Hes5 expression gradually increased. After the administration of DAPT, the expression of Notch, Hes1 and Hes5 was inhibited, apoptosis and oxidative stress decreased, neurological function and cognitive function improved. These results suggest that Notch signaling can be used as an indicator to assess the severity of post-traumatic brain injury. Notch inhibitor DAPT can reduce oxidative stress and apoptosis after acute craniocerebral injury, and is a potential drug for the treatment of acute craniocerebral injury.

  15. Ductile growth of crack like flawing during hydrotest; Propagacao dutil de defeitos planares durante teste hidrostatico

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, Jose C; Donato, Guilherme V [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES); Silva, Marcinei S. da; Bastian, Fernando L [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE); Lima, Romulo S. de [PETROBRAS/AB-RE, Rio de Janeiro, RJ (Brazil)

    2003-07-01

    In this paper effects of hydrostatic testing on ductile propagation of crack like flaw defects were evaluated in API X-60 steel. The model used was based on the J-tearing theory, supported by elastic - plastic fracture mechanics. The J-initiation resistance values (JIc) were determined by fracture mechanic tests using potential drop technique and compact test specimen. The JIc values were also determined from flow stress and Charpy V-notch at plateau, which are both usually available in mill-test data. Despite of being based on small database it seems it could be extended and it will be useful for future analysis. (author)

  16. Weldability of thermally grain-refined Fe-12Ni-0.25Ti for cryogenic structural applications

    International Nuclear Information System (INIS)

    Williams, D.E.

    1980-02-01

    The weldability of a research alloy designed for structural use in liquid helium temperature, cryogenic environments was investigated. Plates of iron-12 weight percent nickel-0.25 weight percent titanium were grain refined by the four-step, grain refining thermal treatment developed for this alloy and welded with Inconel Number 92 weld wire using the Gas Metal Arc (GMA) welding process with argon-15% helium gas shielding. Both a single pass and a double-sided, 2 pass electron beam (EB) weld were also made without filler metal addition. Weldments were radiographed and sectioned and the charpy V-notch specimens removed were tested at liquid nitrogen and helium temperatures

  17. Half bead welding technique

    International Nuclear Information System (INIS)

    Canonico, D.A.; Holz, P.P.

    1978-05-01

    The ORNL has employed the Section XI half-bead procedure for six repair welds. Table 2 identifies the repairs and the components upon which they were accomplished. The weld repairs were performed to permit us to evaluate material properties, residual stresses, weld repair procedures, and structural behavior of repaired pressure vessels. As a consequence of our study we concluded that when the half bead procedure is correctly applied: (1) there is no metallurgical degradation of the base material, (2) residual stresses of yield point magnitude will be present, and (3) the structural integrity of the pressure vessel is not impaired at Charpy V-notch upper shelf temperatures

  18. Redundant Notch1 and Notch2 signaling is necessary for IFNγ secretion by T helper 1 cells during infection with Leishmania major.

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    Floriane Auderset

    Full Text Available The protective immune response to intracellular parasites involves in most cases the differentiation of IFNγ-secreting CD4(+ T helper (Th 1 cells. Notch receptors regulate cell differentiation during development but their implication in the polarization of peripheral CD4(+ T helper 1 cells is not well understood. Of the four Notch receptors, only Notch1 (N1 and Notch2 (N2 are expressed on activated CD4(+ T cells. To investigate the role of Notch in Th1 cell differentiation following parasite infection, mice with T cell-specific gene ablation of N1, N2 or both (N1N2(ΔCD4Cre were infected with the protozoan parasite Leishmania major. N1N2(ΔCD4Cre mice, on the C57BL/6 L. major-resistant genetic background, developed unhealing lesions and uncontrolled parasitemia. Susceptibility correlated with impaired secretion of IFNγ by draining lymph node CD4(+ T cells and increased secretion of the IL-5 and IL-13 Th2 cytokines. Mice with single inactivation of N1 or N2 in their T cells were resistant to infection and developed a protective Th1 immune response, showing that CD4(+ T cell expression of N1 or N2 is redundant in driving Th1 differentiation. Furthermore, we show that Notch signaling is required for the secretion of IFNγ by Th1 cells. This effect is independent of CSL/RBP-Jκ, the major effector of Notch receptors, since L. major-infected mice with a RBP-Jκ deletion in their T cells were able to develop IFNγ-secreting Th1 cells, kill parasites and heal their lesions. Collectively, we demonstrate here a crucial role for RBP-Jκ-independent Notch signaling in the differentiation of a functional Th1 immune response following L. major infection.

  19. Complete Absence of Suprascapular Notch: A Case Report

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    Rohini Mohan Pawar

    2015-10-01

    Full Text Available Suprascapular Nerve Entrapment (SSNE is an acquired neuropathy secondary to compression of suprascapular nerve in the Suprascapular Notch (SSN. Complete ossification of superior transverse scapular ligament may be a cause for suprascapular nerve entrapment. The absence of suprascapular notch is not very common condition, though its prevalence was quoted by Indian authors to be varying from 1.36% to 32.46% in different parts of the country. It is considered to be a predisposing factor for suprascapular nerve entrapment neuropathy. We noticed a male scapula without suprascapular notch in osteology section of Forensic Medicine department. In this case we observed costal and dorsal surfaces of the left scapula of a male without suprascapular notch at its superior border. The details of the said scapula are discussed in this report.

  20. Femoral intercondylar notch shape and dimensions in ACL-injured patients

    NARCIS (Netherlands)

    van Eck, Carola F.; Martins, Cesar A. Q.; Vyas, Shail M.; Celentano, Umberto; van Dijk, C. Niek; Fu, Freddie H.

    2010-01-01

    The femoral intercondylar notch has been an anatomic site of interest as it houses the anterior cruciate ligament (ACL). The objective of this study was to arthroscopically evaluate the femoral notch in patients with known ACL injury. This evaluation included establishing a classification for notch

  1. Irradiation damage behavior of low alloy steel wrought and weld materials

    International Nuclear Information System (INIS)

    Stofanak, R.J.; Poskie, T.J.; Li, Y.Y.; Wire, G.L.

    1993-01-01

    A study was undertaken to evaluate the irradiation damage response of several different types of low alloy steel: vintage type ASTM A302 Grade B (A302B) plates and welds containing different Ni and Cu concentrations, 3.5% Ni steels similar to ASTM A508 Class 4, welds containing about 1% Ni (similar to type 105S), and 3.5% Ni steels with ''superclean'' composition. All materials were irradiated at several different irradiation damage levels ranging from 0.0003 to 0.06 dpa at 232C (450F). Complete Charpy V-notch impact energy transition temperature curves were generated for all materials before and after irradiation to determine transition temperature at 4IJ (30 ft-lb) or 47J (35 ft-lb) and the upper shelf energy. Irradiation damage behavior was measured by shift in Charpy 41J or 47J transition temperature (ΔTT4 41J or ΔTT 47J ) and lowering of upper shelf Charpy energy at a given irradiation damage level. It was found that chemical composition greatly influenced irradiation damage behavior; highest irradiation damage (greatest ΔTT) was found in an A302B type weld containing 1.28% Ni and 0.20% Cu while the least damage was found in 3.5% Ni, 0.05% Cu, superclean wrought materials. Combination of Ni and Cu was found to affect irradiation damage behavior at higher irradiation damage levels in the A302B welds where the 1.28% Ni, 0.20% Cu weld showed more damage than a 0.60% Ni, 0.31% Cu weld. For the 3.5% Ni steels, fabrication influenced irradiation behavior in that a silicon (Si) killed material showed greater irradiation damage than a low silicon material. In general, the 3.5% Ni materials with low copper showed less irradiation damage than the A302B materials

  2. Propriedades mecânicas e resistência à corrosão da liga Ti-4Al-4V obtida da reciclagem da liga Ti-6Al-4V

    Directory of Open Access Journals (Sweden)

    Jesuíno G.A.

    2001-01-01

    Full Text Available The present work aimed to study the transformation from as-cast structure of the Ti4Al-4V alloy, as a result of the Ti-6Al-4V recycling, after some rapid heat treatments based on martensitic reactions. The effects on mechanical properties were evaluated by Vickers hardness measurements, Charpy and monotonic tensile tests. The corrosion strength was tested by immersion during 4 months in artificial physiological solutions, to evaluate its possible use as a biomaterial. The data pointed to: a a reduction on corrosion strength for quenching above beta transus; b significant increasing on hardness and mechanical strength; c a maintenance of impact toughness; d the corrosion strength for immersion in a NaCl 1%+ NaF 0,1% (m/m was lower in all conditions, specially for those including heating to 900 °C.

  3. Determination of ASTM 1016 structural welded joints fracture toughness through J integral

    International Nuclear Information System (INIS)

    Martins, Geraldo de Paula; Villela, Jefferson Jose; Terra, Jose Lucio; Rabello, Emerson Giovani; Martins, Geraldo Antonio Scoralick; Carneiro, Jose Rubens Goncalves

    2009-01-01

    Fracture toughness is an important parameter for studies of materials behavior in nuclear and conventional industry. Crack propagation resistance is, in general, evaluate using one of the fracture mechanics parameters K IC , for the case of the materials that exhibits a linear elastic behavior, the CTOD (crack tip opening displacement) and J IC , the critical value of J Integral, for the case of materials with elastic-plastic behavior. On this work the fracture mechanics parameters of the ASTM 1016 structural steel welded joints were obtained, using the J Integral. Charpy V tests at several temperatures were also obtained, with the purpose to obtain the curves of ductile-brittle of the regions of the welded joints: Base Metal, (MB), and Melted Zone (MZ). The joints were welded by Gas Metal Arc Welding (GMAW) with V bevel for evaluation the MZ toughness properties. The tests were accomplished at temperatures varying from -100 deg C to 100 deg C using the technical of compliance variation for J IC determination, the critical value that defines the initial stable crack growth, that applies to brittle and ductile materials. The J Integral alternative specimens has square cross section 10mmX10mm, according ASTM E 1820, with notch localized respectively at the BM and MZ. After the tests, the specimens fractured were analyzed in a scanning microscopic electronic (SME) for verification of the fracture surface. The fractography of the specimens at elevated temperatures presented dimples at the region of stable crack growth, characteristic of ductile fracture. The results of J Integral and Charpy V presented a good correlation between these two parameters. From these correlations it can be concluded that in some applications, the use Charpy V energy to infer fracture toughness can be substitute the Integral J tests. (author)

  4. Expression of Notch1 Correlates with Breast Cancer Progression and Prognosis.

    Directory of Open Access Journals (Sweden)

    Xun Yuan

    Full Text Available Various studies have evaluated the significance of Notch1 expression in breast cancer, but the results have ever been disputed. By using 21 studies involving 3867 patients, this meta-analysis revealed that the expression of Notch1 was significantly higher in breast cancer than in normal tissues (OR=7.21; 95%CI, 4.7-11.07 and that higher Notch1 expression was associated with transition from ductal carcinoma in situ (DCIS to invasive cancer (OR=3.75; 95% CI, 1.8-7.78. Higher Notch1 activity was observed in the basal subtype of breast cancer (OR=2.53; 95% CI, 1.18-5.43. Moreover, patients with Notch1 overexpression exhibited significantly worse overall and recurrence-free survival. Our meta-analysis suggests that Notch inhibitors may be useful in blocking the early progression of DCIS and that the outcomes of clinical trials for Notch1-targeting therapeutics could be improved by the molecular stratification of breast cancer patients.

  5. Functional studies on the role of Notch signaling in Hydractinia development.

    Science.gov (United States)

    Gahan, James M; Schnitzler, Christine E; DuBuc, Timothy Q; Doonan, Liam B; Kanska, Justyna; Gornik, Sebastian G; Barreira, Sofia; Thompson, Kerry; Schiffer, Philipp; Baxevanis, Andreas D; Frank, Uri

    2017-08-01

    The function of Notch signaling was previously studied in two cnidarians, Hydra and Nematostella, representing the lineages Hydrozoa and Anthozoa, respectively. Using pharmacological inhibition in Hydra and a combination of pharmacological and genetic approaches in Nematostella, it was shown in both animals that Notch is required for tentacle morphogenesis and for late stages of stinging cell maturation. Surprisingly, a role for Notch in neural development, which is well documented in bilaterians, was evident in embryonic Nematostella but not in adult Hydra. Adult neurogenesis in the latter seemed to be unaffected by DAPT, a drug that inhibits Notch signaling. To address this apparent discrepancy, we studied the role of Notch in Hydractinia echinata, an additional hydrozoan, in all life stages. Using CRISPR-Cas9 mediated mutagenesis, transgenesis, and pharmacological interference we show that Notch is dispensable for Hydractinia normal neurogenesis in all life stages but is required for the maturation of stinging cells and for tentacle morphogenesis. Our results are consistent with a conserved role for Notch in morphogenesis and nematogenesis across Cnidaria, and a lineage-specific loss of Notch dependence in neurogenesis in hydrozoans. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. A Compact Printed Quadruple Band-Notched UWB Antenna

    Directory of Open Access Journals (Sweden)

    Xiaoyin Li

    2013-01-01

    Full Text Available A novel compact coplanar waveguide- (CPW- fed ultrawideband (UWB printed planar volcano-smoke antenna (PVSA with four band-notches for various wireless applications is proposed and demonstrated. The low-profile antenna consists of a C-shaped parasitic strip to generate a notched band at 8.01~8.55 GHz for the ITU band, two C-shaped slots, and an inverted U-shaped slot etched in the radiator patch to create three notched bands at 5.15~5.35 GHz, 5.75~5.85 GHz, and 7.25~7.75 GHz for filtering the WLAN and X-band satellite signals. Simulated and measured results both confirm that the proposed antenna has a broad bandwidth of 3.1~12 GHz with VSWR < 2 and good omnidirectional radiation patterns with four notched-bands.

  7. Cell proliferation control by Notch signalling during imaginal discs development in Drosophila

    Directory of Open Access Journals (Sweden)

    Carlos Estella

    2015-02-01

    Full Text Available The Notch signalling pathway is evolutionary conserved and participates in numerous developmental processes, including the control of cell proliferation. However, Notch signalling can promote or restrain cell division depending on the developmental context, as has been observed in human cancer where Notch can function as a tumor suppressor or an oncogene. Thus, the outcome of Notch signalling can be influenced by the cross-talk between Notch and other signalling pathways. The use of model organisms such as Drosophila has been proven to be very valuable to understand the developmental role of the Notch pathway in different tissues and its relationship with other signalling pathways during cell proliferation control. Here we review recent studies in Drosophila that shed light in the developmental control of cell proliferation by the Notch pathway in different contexts such as the eye, wing and leg imaginal discs. We also discuss the autonomous and non-autonomous effects of the Notch pathway on cell proliferation and its interactions with different signalling pathways.

  8. Optical stress investigations of notched bars with superimposed types of loads

    International Nuclear Information System (INIS)

    Richard, H.A.; Theis, W.

    1982-01-01

    Starting from the notch effect for various types of load, notch stresses are determined by optical methods for superimposed tensile and shearing stress and for superimposed tensile and bending stress. The superimposed stresses are induced by a device developed at the Technical Mechanics Department of Kaiserslautern University; only tensile stress needs to be applied to this testing device. The investigations have shown that in notched bars subject to superimposed tensile and shearing stress, stress increases will be higher than the maximum values of the two types of stress. For superimposed tensile and bending stress, notches on the outer side of the test piece and eccentric notches on the inner side may lead to a considerable stress increase. However, the stress distribution can be improved by an optimum arrangement of notches. (orig.) [de

  9. Stress intensity factors and weight functions for cracks in front of notches

    International Nuclear Information System (INIS)

    Fett, T.

    1993-12-01

    The knowledge of stress intensity factors for cracks at notch roots is important for the fracture mechanical treatment of real components. Stress intensity factor solutions are available only for special notches and externally applied loads. For the treatment of more complex loadings as thermal stresses near the notch root the weight function is needed in addition. In the first part of this report weight functions for cracks in front of internal notches are derived from stress intensity factor solutions under external loading available in the literature. The second part deals with cracks in front of edge notches. Limit cases of stress intensity factors are derived which allow to estimate stress intensity factors for cracks in front of internal elliptical notches with arbitrary aspect ratio of the ellipse and for external notches. (orig.) [de

  10. Notched K-wire for low thermal damage bone drilling.

    Science.gov (United States)

    Liu, Yao; Belmont, Barry; Wang, Yiwen; Tai, Bruce; Holmes, James; Shih, Albert

    2017-07-01

    The Kirschner wire (K-wire) is a common bone drilling tool in orthopedic surgery to affix fractured bone. Significant heat is produced due to both the cutting and the friction between the K-wire and the bone debris during drilling. Such heat can result in high temperatures, leading to osteonecrosis and other secondary injuries. To reduce thermal injury and other high-temperature associated complications, a new K-wire design with three notches along the three-plane trocar tip fabricated using a thin micro-saw tool is studied. These notches evacuate bone debris and reduce the clogging and heat generation during bone drilling. A set of four K-wires, one without notches and three notched, with depths of 0.5, 0.75, and 1mm, are evaluated. Bone drilling experiments conducted on bovine cortical bone show that notched K-wires could effectively decrease the temperature, thrust force, and torque during bone drilling. K-wires with notches 1mm deep reduced the thrust force and torque by approximately 30%, reduced peak temperatures by 43%, and eliminated blackened burn marks in bone. This study demonstrates that a simple modification of the tip of K-wires can effectively reduce bone temperatures during drilling. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  11. Evaluation of ductile-brittle transition behavior with neutron irradiation in nuclear reactor pressure vessel steels using small punch test

    International Nuclear Information System (INIS)

    Kim, M. C.; Lee, B. S.; Oh, Y. J.

    2003-01-01

    A Small Punch (SP) test was performed to evaluate the ductile-brittle transition temperature before and after neutron irradiation in Reactor Pressure Vessel (RPV) steels produced by different manufacturing (refining) processes. The results were compared to the standard transition temperature shifts from the Charpy test and Master Curve fracture toughness test in accordance with the ASTM standard E1921. The samples were taken from 1/4t location of the vessel thickness and machined into a 10x10x0.5mm dimension. Irradiation of the samples was carried out in the research reactor at KAERI (HANARO) at about 290 .deg. C of the different fluence levels respectively. SP tests were performed in the temperature range of RT to -196 .deg. C using a 2.4mm diameter ball. For the materials before and after irradiation, SP transition temperatures (T sp ), which are determined at the middle of the upper and lower SP energies, showed a linear correlation with the Charpy index temperature, T 41J . T sp from the irradiated samples was increased as the fluence level increased and was well within the deviation range of the unirradiated data. The TSP had a correlation with the reference temperature (T 0 ) from the master curve method using a pre-cracked Charpy V-notched (PCVN) specimen

  12. Role of Notch Signaling in Human Breast Cancer Pathogenesis

    Science.gov (United States)

    2006-11-01

    transform HMLE cells. Similarly, overexpression of ErbB2, a receptor tyrosine kinase upstream of Ras normally found overexpressed in many breast cancers ...Assess Notch-Ras cooperation in breast cancers in vivo: Since the major observation in this project has been the cooperation of Notch and Ras in HMLE ...metastasis. The in vitro cooperation between Notch and Ras in HMLE cells is mimicked in naturally arising breast cancers in vivo. Further dissection of the

  13. Notch signaling and ghost cell fate in the calcifying cystig odontogenic tumor

    Directory of Open Access Journals (Sweden)

    Siar CH

    2011-11-01

    Full Text Available Abstract Notch signaling is an evolutionarily conserved mechanism that enables adjacent cells to adopt different fates. Ghost cells (GCs are anucleate cells with homogeneous pale eosinophilic cytoplasm and very pale to clear central areas (previous nucleus sites. Although GCs are present in a variety of odontogenic lesions notably the calcifying cystic odontogenic tumor (GCOT, their nature and process of formation remains elusive. The aim of this study was to investigate the role of Notch signaling in the cell fate specification of GCs in CCOT. Immunohistochemical staining for four Notch receptors (Notch1, Notch2, Notch3 and Notch4 and three ligands (Jagged1, Jagged2 and Delta1 was performed on archival tissues of five CCOT cases. Level of positivity was quantified as negative (0, mild (+, moderate (2+ and strong (3+. Results revealed that GCs demonstrated overexpression for Notch1 and Jagged1 suggesting that Notch1Jagged1 signaling might serve as the main transduction mechanism in cell fate decision for GCs in CCOT. Protein localizations were largely membranous and/or cytoplasmic. Mineralized GCs also stained positive implicating that the calcification process might be associated with upregulation of these molecules. The other Notch receptors and ligands were weak to absent in GCs and tumoral epithelium. Stromal endothelium and fibroblasts were stained variably positive.

  14. In-situ tensile testing of notched poly- and oligocrystalline 316L wires

    Energy Technology Data Exchange (ETDEWEB)

    Mitevski, Bojan [Materials Science and Engineering (ITM), Duisburg (Germany); Weiss, Sabine [Brandenburg Technical Univ., Cottbus-Senftenberg (Germany). Chair of Physical Metallurgy and Materials Science.; Fischer, Alfons [Duisburg-Essen Univ. (Germany). Materials Science and Engineering; Rush Univ. Medical Center, Chicago, IL (United States). Dept. of Orthopedics

    2017-03-01

    In-situ testing inside a scanning electron microscope is a helpful tool for detailed analyses of small sized specimens with respect to their mechanical properties and the correlated microstructural alterations. Thus, this test method is used to analyze the tensional properties of thin 316L (1.4441) wires used for microscale components, e.g., like coronary artery stents. Tensile tests were conducted on unnotched and circularly notched 316L wires (oe 0.95 mm) with a special focus on the number of grains within the cross section as well as the notch geometry. Four combinations of notch width (2 and 4 mm) and notch depth (diameter at notch root: 0.5 and 0.75 mm) were chosen. Notch depth and notch shape were adjusted by means of electrochemical polishing. Previous investigations showed, that oligocrystalline structures exhibit a different mechanical behavior compared to polycrystalline ones or single crystals. There are only a few data available on mechanical testing of oligocrystalline structures with respect to varying notch geometries. Depending on the notch geometry, grain size and, therefore, the number of grains within the notch cross section widely scattering yield- and tensile strength as well as failure elongation values were measured. However, the transition criterion between poly- and oligocrystalline behavior could be quantified to be 6 to 7 grains within the cross section.

  15. Notch Signaling Mediates Skeletal Muscle Atrophy in Cancer Cachexia Caused by Osteosarcoma

    Directory of Open Access Journals (Sweden)

    Xiaodong Mu

    2016-01-01

    Full Text Available Skeletal muscle atrophy in cancer cachexia is mediated by the interaction between muscle stem cells and various tumor factors. Although Notch signaling has been known as a key regulator of both cancer development and muscle stem cell activity, the potential involvement of Notch signaling in cancer cachexia and concomitant muscle atrophy has yet to be elucidated. The murine K7M2 osteosarcoma cell line was used to generate an orthotopic model of sarcoma-associated cachexia, and the role of Notch signaling was evaluated. Skeletal muscle atrophy was observed in the sarcoma-bearing mice, and Notch signaling was highly active in both tumor tissues and the atrophic skeletal muscles. Systemic inhibition of Notch signaling reduced muscle atrophy. In vitro coculture of osteosarcoma cells with muscle-derived stem cells (MDSCs isolated from normal mice resulted in decreased myogenic potential of MDSCs, while the application of Notch inhibitor was able to rescue this repressed myogenic potential. We further observed that Notch-activating factors reside in the exosomes of osteosarcoma cells, which activate Notch signaling in MDSCs and subsequently repress myogenesis. Our results revealed that signaling between tumor and muscle via the Notch pathway may play an important role in mediating the skeletal muscle atrophy seen in cancer cachexia.

  16. Notch inhibition counteracts Paneth cell death in absence of caspase-8.

    Science.gov (United States)

    Jeon, M K; Kaemmerer, E; Schneider, U; Schiffer, M; Klaus, C; Hennings, J; Clahsen, T; Ackerstaff, T; Niggemann, M; Schippers, A; Longerich, T; Sellge, G; Trautwein, C; Wagner, N; Liedtke, C; Gassler, N

    2018-05-16

    Opposing activities of Notch and Wnt signaling regulate mucosal barrier homeostasis and differentiation of intestinal epithelial cells. Specifically, Wnt activity is essential for differentiation of secretory cells including Wnt3-producing Paneth cells, whereas Notch signaling strongly promotes generation of absorptive cells. Loss of caspase-8 in intestinal epithelium (casp8 ∆int ) is associated with fulminant epithelial necroptosis, severe Paneth cell death, secondary intestinal inflammation, and an increase in Notch activity. Here, we found that pharmacological Notch inhibition with dibenzazepine (DBZ) is able to essentially rescue the loss of Paneth cells, deescalate the inflammatory phenotype, and reduce intestinal permeability in casp8 ∆int mice. The secretory cell metaplasia in DBZ-treated casp8 ∆int animals is proliferative, indicating for Notch activities partially insensitive to gamma-secretase inhibition in a casp8 ∆int background. Our data suggest that casp8 acts in the intestinal Notch network.

  17. Notch 1 as a potential therapeutic target in cutaneous T-cell lymphoma

    DEFF Research Database (Denmark)

    Kamstrup, Maria Rørbæk; Gjerdrum, Lise Mette Rahbek; Biskup, Edyta Urszula

    2010-01-01

    Deregulation of Notch signaling has been linked to the development of T-cell leukemias and several solid malignancies. Yet, it is unknown whether Notch signalling is involved in the pathogenesis of mycosis fungoides and Sezary syndrome, the most common subtypes of cutaneous T cell lymphoma....... By immunohistochemistry of 40 biopsies taken from skin lesions of mycosis fungoides and Sezary syndrome we demonstrated prominent expression of Notch1 on tumor cells, especially in the more advanced stages. The gamma-secretase inhibitor I blocked Notch signaling and potently induced apoptosis in cell lines derived from...... mycosis fungoides (MyLa) and Sezary syndrome (SeAx, HuT-78)and in primary leukemic Sézary cells. Specific downregulation of Notch1 (but not Notch2 and Notch3) by siRNA induced apoptosis in SeAx. The mechanism of apoptosis involved the inhibition of NF-kappaB, which is the most important prosurvival...

  18. Evaluation of notch effects in low cycle fatigue of alloy 718 using critical distances

    Directory of Open Access Journals (Sweden)

    Eriksson Robert

    2018-01-01

    Full Text Available Gas turbine disks contain many notch-like features acting as stress raisers. The fatigue life based on the notch root stress may be overly conservative as the steep stress gradient in front of the notch may give rise to so-called notch support. In the current work, the theory of critical distances was applied to the prediction of the total fatigue life of low cycle fatigued, notched specimens made from alloy 718. The fatigue tests were performed at 450 °C and 550 °C. It was found that, for lives shorter than 5000–10000 cycles, the notched specimens had longer lives than would have been expected based on the notch root strain. For lives longer than 5000–10000 cycles, there were no notch support. The life prediction for notched specimens could be significantly improved by basing the prediction on the strain chosen some distance from the notch (the critical distance. An expression for calculating the critical distance based on the notch root strain was suggested.

  19. Cell-Cell Contact Area Affects Notch Signaling and Notch-Dependent Patterning.

    Science.gov (United States)

    Shaya, Oren; Binshtok, Udi; Hersch, Micha; Rivkin, Dmitri; Weinreb, Sheila; Amir-Zilberstein, Liat; Khamaisi, Bassma; Oppenheim, Olya; Desai, Ravi A; Goodyear, Richard J; Richardson, Guy P; Chen, Christopher S; Sprinzak, David

    2017-03-13

    During development, cells undergo dramatic changes in their morphology. By affecting contact geometry, these morphological changes could influence cellular communication. However, it has remained unclear whether and how signaling depends on contact geometry. This question is particularly relevant for Notch signaling, which coordinates neighboring cell fates through direct cell-cell signaling. Using micropatterning with a receptor trans-endocytosis assay, we show that signaling between pairs of cells correlates with their contact area. This relationship extends across contact diameters ranging from micrometers to tens of micrometers. Mathematical modeling predicts that dependence of signaling on contact area can bias cellular differentiation in Notch-mediated lateral inhibition processes, such that smaller cells are more likely to differentiate into signal-producing cells. Consistent with this prediction, analysis of developing chick inner ear revealed that ligand-producing hair cell precursors have smaller apical footprints than non-hair cells. Together, these results highlight the influence of cell morphology on fate determination processes. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Degradación de la tenacidad al impacto durante el envejecimiento acelerado de soldadura en acero microaleado

    Directory of Open Access Journals (Sweden)

    Vargas-Arista, B.

    2008-12-01

    Full Text Available The effect of accelerated aging on the toughness and fracture of the longitudinal weld metal of an API5L-X52 linepipe steel was evaluated by Charpy V-notch impact test, fracture analysis and transmission electron microscopy. Aging was performed at 250 °C for 100 to 1000 h. The impact results indicated a significant reduction in the fracture energy and impact toughness as a function of aging time, which were achieved by the scanning electron microscope fractographs that showed a decrease in the vol fraction of microvoids by Charpy ductile failure with the aging time, which favored the brittle fracture by transgranular cleavage. The minimum vol fraction of microvoids was reached at 500 h due to the peak-aged. The microstructural analysis indicated the precipitation of transgranular iron nanocarbides in the aged specimens, which was related to the deterioration of toughness and change in the ductile to brittle behavior.

    Se evaluó, mediante el ensayo de impacto Charpy, fractografía y microscopia electrónica de transmisión el efecto del envejecimiento acelerado sobre la tenacidad y fractura de la soldadura en tubería de acero API5L-X52. El envejecimiento se realizó a 250 °C por 1.000 h, con control cada 100 h. Los resultados de impacto indicaron una disminución en la energía de fractura y tenacidad al impacto en función del tiempo del envejecimiento, los cuales se evidenciaron mediante fractografía, por la reducción en la fracción volumétrica de microhuecos por fractura dúctil con el tiempo, favoreciendo la fractura frágil por clivaje transgranular. Sin embargo, a 500 h, se observó la fracción volumétrica mínima debido al pico del envejecimiento. El análisis microestructural evidenció la precipitación de nanocarburos de hierro transgranulares en las muestras envejecidas, la cual se relaciono con la pérdida de tenacidad y cambio en el comportamiento dúctil a frágil, confirmado por fractografía.

  1. Partial-Isothermally-Treated Low Alloy Ultrahigh Strength Steel with Martensitic/Bainitic Microstructure

    Science.gov (United States)

    Luo, Quanshun; Kitchen, Matthew; Patel, Vinay; Filleul, Martin; Owens, Dave

    We introduce a new strengthening heat treatment of a Ni-Cr-Mo-V alloyed spring steel by partial isothermal salt-bath and subsequent air-cooling and tempering. Detailed isothermal treatments were made at temperatures below or above the Ms point (230°C). The salt bath time was controlled between 10 and 80 minutes. Through the new treatment, the candidate steel developed ultrahigh tensile strength 2,100 MPa, yield strength 1,800 MPa, elongation 8-10 %, hardness 580-710 HV, and V-notch Charpy toughness 10-12 J. Optical and electron microscopic observations and X-ray diffraction revealed multi-phase microstructures of bainitic/martensitic ferrites, fine carbide precipitates and retained austenite. Carbon partitioning during the bainitic/martensitic transformation was investigated for its remarkable influence on the strengthening mechanism.

  2. Effect of notch and alloying on steel properties during extension

    International Nuclear Information System (INIS)

    Vinokur, B.B.; Pilyushenko, U.L.; Kasatkin, O.G.

    1985-01-01

    A study was made on change of strength and plastic characteristics during extension of notched steel samples of 15 compositions containing often-used alloying elements in various amounts and combinations. The notch causes increase of strength and decrease of plastic properties of structural steels during extension. The most pronounced change of properties takes place for the notched sample with expansion angle close to 180 deg. Reduction of notch expansion angle below 150 deg causes slower decrease of the rate of property change. Nickel alloying and vanadium, titanium microalloying assist the improvement of steel plasticity despite the increase of strength properties. Introduction of these elements in steel compensate partially for the negative notch effect. Alloying by silicon, molybdenum and tungsten results in steel strengthening and chromium alloying causes some loss of strength. Manse, chromium, silicon, molybdenum and tungsten cause decrease of plasticity, which intensifies the negative notch effect. When determining concentration ranges of carbon and alloying elements within the limits of quality composition it is necessary to consider both technology and possibility of sufficient change of properties especially in the case of stress concentrator presence in structures

  3. Notch co-operates with Lozenge/Runx to lock hemocytes into a differentiation programme

    Czech Academy of Sciences Publication Activity Database

    Terriente-Felix, A.; Li, J.; Collins, S.; Mulligan, A.; Reekie, I.; Bernard, F.; Krejčí, Alena; Bray, S.

    2013-01-01

    Roč. 140, č. 4 (2013), s. 926-937 ISSN 0950-1991 R&D Projects: GA ČR(CZ) GAP305/11/0126 Grant - others:MRC programme(GB) G0800034 Institutional support: RVO:60077344 Keywords : Lozenge/Runx * Notch * chromatin immunoprecipitation Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 6.273, year: 2013

  4. Insensible is a novel nuclear inhibitor of Notch activity in Drosophila.

    Directory of Open Access Journals (Sweden)

    Franck Coumailleau

    Full Text Available Notch signalling regulates a wide range of developmental processes. In the Drosophila peripheral nervous system, Notch regulates a series of binary fate decisions that lead to the formation of regularly spaced sensory organs. Each sensory organ is generated by single sensory organ precursor cell (SOP via a series of asymmetric cell divisions. Starting from a SOP-specific Cis-Regulatory Module (CRM, we identified insensible (insb, a.k.a CG6520, as a SOP/neuron-specific gene encoding a nuclear factor that inhibits Notch signalling activity. First, over-expression of Insb led to the transcriptional repression of a Notch reporter and to phenotypes associated with the inhibition of Notch. Second, while the complete loss of insb activity had no significant phenotype, it enhanced the bristle phenotype associated with reduced levels of Hairless, a nuclear protein acting as a co-repressor for Suppressor of Hairless. In conclusion, our work identified Insb as a novel SOP/neuron-specific nuclear inhibitor of Notch activity in Drosophila.

  5. Immunohistochemical analysis of the role and relationship between Notch-1 and Oct-4 expression in urinary bladder carcinoma.

    Science.gov (United States)

    Abdou, Asmaa Gaber; El-Wahed, Moshira Mohammed Abd; Kandil, Mona Abd-Elhalim; Samaka, Rehab Monir; Elkady, Noha

    2013-10-01

    Most tumors contain a minor population of cancer stem cells that are responsible for tumor heterogeneity, resistance to therapy and recurrence. Oct-4 is a transcription factor responsible for self-renewal of stem cells, whereas the Notch family of receptors and ligands may play a pivotal role in the regulation of stem cell maintenance and differentiation. This study aimed at an evaluation of Oct-4 and Notch-1 expression in both carcinoma and stromal cells of 83 cases of primary bladder carcinoma and to study the relationship between them. Notch-1 was expressed in carcinoma and stromal cells of all malignant cases, where expression in both cell types was correlated with parameters indicating differentiation, such as low grade (p bladder carcinoma, such as poor differentiation (p = 0.001), high proliferation (p bladder carcinoma, where they may cooperate in the progression of bladder carcinoma by acquiring aggressive features, such as a liability for recurrence and dissemination. Notch-1 is also expressed in both carcinoma cells and stromal cells of bladder carcinoma. Although they could share in enhancing differentiation, stromal expression of Notch-1 may have a bad impact, possibly through up-regulation of the active nuclear form of Oct-4 in carcinoma cells. © 2013 APMIS Published by Blackwell Publishing Ltd.

  6. Feasibility of and methodology for thermal annealing an embrittled reactor vessel. Volume 2. Detailed technical description of the work. Final report

    International Nuclear Information System (INIS)

    Mager, T.R.

    1982-11-01

    Program materials were three weldments fabricated from A533 Grade B class 1 plate material and Mn Mo Ni weld wire. Specimens fabricated from the three submerged arc weldments included Type A Charpy V-notch impact, small size tensile, and 1/2T compact tension specimens. After encapsulation, the specimens were irradiated at the UVAR to two fluence levels, 8 x 10 18 n/cm 2 and 1.5 x 10 19 n/cm 2 (E > 1 MeV). Specimens were subjected to sequences of irradiation and anneals and then tested. Metallurgial/mechanistic analyses were also performed. It was concluded that excellent recovery of all properties could be achieved by annealing at greater than or equal to 850 0 F (454 0 C) for 168 hours. Such an annealing resulted in ductile-brittle transition temperature shift recovery of 80 to 100%, and reirradiation after this annealing indicated that the ductile-brittle transition temperature shift appears to continue at the expected rate. Several drawbacks were identified for wet thermal annealing. A conceptual dry in-situ thermal annealing procedure was developed for thermal annealing embrittled reactor vessels

  7. Manic fringe inhibits tumor growth by suppressing Notch3 degradation in lung cancer.

    Science.gov (United States)

    Yi, Fuming; Amarasinghe, Baru; Dang, Thao P

    2013-01-01

    Notch signaling plays an essential role in development as well as cancer. We have previously shown that Notch3 is important for lung cancer growth and survival. Notch receptors are activated through the interaction with their ligands, resulting in proteolytic cleavage of the receptors. This interaction is modulated by Fringe, a family of fucose-specific β1,3 N-acetylglucosaminyltransferases that modify the extracellular subunit of Notch receptors. Studies in developmental models showed that Fringe enhances Notch's response to Delta ligands at the expense of Jagged ligands. We observed that Manic Fringe expression is down-regulated in lung cancer. Since Jagged1, a known ligand for Notch3, is often over-expressed in lung cancer, we hypothesized that Fringe negatively regulates Notch3 activation. In this study, we show that re-expression of Manic Fringe down-regulates Notch3 target genes HES1 and HeyL and reduces tumor phenotype in vitro and in vivo. The mechanism for this phenomenon appears to be related to modulation of Notch3 protein stability. Proteasome inhibition reverses Manic Fringe-induced protein turnover. Taken together, our data provide the first evidence that Manic Fringe functions as a tumor suppressor in the lung and that the mechanism of its anti-tumor activity is mediated by inhibition of Notch3 activation.

  8. hCLP46 regulates U937 cell proliferation via Notch signaling pathway

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Wenzhan; Du, Jie; Chu, Qiaoyun [College of Life Science, Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Youxin [School of Public Health and Family Medicine, Capital Medical University, Beijing 100069 (China); Liu, Lixin [College of Life Science, Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Song, Manshu [School of Public Health and Family Medicine, Capital Medical University, Beijing 100069 (China); Wang, Wei, E-mail: wei6014@yahoo.com [College of Life Science, Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); School of Public Health and Family Medicine, Capital Medical University, Beijing 100069 (China)

    2011-04-29

    Highlights: {yields} Knock down of hCLP46 by RNAi impairs mammalian Notch signaling. {yields} hCLP46 affects neither cell surface Notch1 expression nor ligand-receptor binding. {yields} Knock down of hCLP46 inhibits U937 cell-growth by up-regulation of CDKN1B. -- Abstract: Human CAP10-like protein 46 kDa (hCLP46) is the homolog of Rumi, which is the first identified protein O-glucosyltransferase that modifies Notch receptor in Drosophila. Dysregulation of hCLP46 occurs in many hematologic diseases, but the role of hCLP46 remains unclear. Knockdown of hCLP46 by RNA interference resulted in decreased protein levels of endogenous Notch1, Notch intracellular domain (NICD) and Notch target gene Hes-1, suggesting the impairment of the Notch signaling. However, neither cell surface Notch expression nor ligand binding activities were affected. In addition, down-regulated expression of hCLP46 inhibited the proliferation of U937 cells, which was correlated with increased cyclin-dependent kinase inhibitor (CDKI) CDKN1B (p27) and decreased phosphorylation of retinoblastoma (RB) protein. We showed that lack of hCLP46 results in impaired ligand induced Notch activation in mammalian cell, and hCLP46 regulates the proliferation of U937 cell through CDKI-RB signaling pathway, which may be important for the pathogenesis of leukemia.

  9. Fringe proteins modulate Notch-ligand cis and trans interactions to specify signaling states.

    Science.gov (United States)

    LeBon, Lauren; Lee, Tom V; Sprinzak, David; Jafar-Nejad, Hamed; Elowitz, Michael B

    2014-09-25

    The Notch signaling pathway consists of multiple types of receptors and ligands, whose interactions can be tuned by Fringe glycosyltransferases. A major challenge is to determine how these components control the specificity and directionality of Notch signaling in developmental contexts. Here, we analyzed same-cell (cis) Notch-ligand interactions for Notch1, Dll1, and Jag1, and their dependence on Fringe protein expression in mammalian cells. We found that Dll1 and Jag1 can cis-inhibit Notch1, and Fringe proteins modulate these interactions in a way that parallels their effects on trans interactions. Fringe similarly modulated Notch-ligand cis interactions during Drosophila development. Based on these and previously identified interactions, we show how the design of the Notch signaling pathway leads to a restricted repertoire of signaling states that promote heterotypic signaling between distinct cell types, providing insight into the design principles of the Notch signaling system, and the specific developmental process of Drosophila dorsal-ventral boundary formation.

  10. Low temperature impact testing of welded structural wrought iron

    Science.gov (United States)

    Rogers, Zachary

    During the second half of the 19th century, structural wrought iron was commonly used in construction of bridges and other structures. Today, these remaining structures are still actively in use and may fall under the protection of historic preservation agencies. Continued use and protection leads to the need for inspection, maintenance, and repair of the wrought iron within these structures. Welding can be useful to achieve the appropriate repair, rehabilitation, or replacement of wrought iron members. There is currently very little published on modern welding techniques for historic wrought iron. There is also no pre-qualified method for this welding. The demand for welding in the repair of historic structural wrought iron has led to a line of research investigating shielded metal arc welding (SMAW) of historic wrought iron at the University of Colorado Denver. This prior research selected the weld type and other weld specifications to try and achieve a recognized specific welding procedure using modern SMAW technology and techniques. This thesis continues investigating SMAW of historic wrought iron. Specifically, this thesis addresses the toughness of these welds from analysis of the data collected from performing Charpy V-Notch (CVN) Impact Tests. Temperature was varied to observe the material response of the welds at low temperature. The wrought iron used in testing was from a historic vehicle bridge in Minnesota, USA. This area, and many other areas with wrought iron structures, can experience sustained or fluctuating temperatures far below freezing. Investigating the toughness of welds in historic wrought iron at these temperatures is necessary to fully understand material responses of the existing structures in need of maintenance and repair. It was shown that welded wrought iron is tougher and more ductile than non-welded wrought iron. In regards to toughness, welding is an acceptable repair method. Information on wrought iron, low temperature failure

  11. Effect of microstructure on the susceptibility of a 533 steel to temper embrittlement

    Energy Technology Data Exchange (ETDEWEB)

    Raoul, S.; Marini, B. [CEA Centre d`Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France). Service de Recherches Metallurgiques Appliquees; Pineau, A. [CNRS, Evry (France). Centre de Materiaux

    1998-11-01

    In ferritic steels, brittle fracture usually occurs at low temperature by cleavage. However the segregation of impurities (P, As, Sn etc..) along prior {gamma} grain boundaries can change the brittle fracture mode from transgranular to intergranular. In quenched and tempered steels, this segregation is associated with what is called the temper-embrittlement phenomenon. The main objective of the present study is to investigate the influence of the as-quenched microstructure (lower bainite or martensite) on the susceptibility of a low alloy steel (A533 cl.1) to temper-embrittlement. Dilatometric tests were performed to determine the continous-cooling-transformation (CCT) diagram of the material and to measure the critical cooling rate (V{sub c}) for a martensitic quench. Then subsized Charpy V-notched specimens were given various cooling rates from the austenitization temperature to obtain a wide range of as-quenched microstructures, including martensite and bainite. These specimens were subsequently given a heat treatment to develop temper embrittlement and tested to measure the V-notch fracture toughness at -50 C. The fracture surfaces were examined by SEM. It is shown that martensitic microstructures are more susceptible to intergranular embrittlement than bainitic microstructures. These observed microstructural influences are briefly discussed. (orig.) 11 refs.

  12. TLX1 and NOTCH coregulate transcription in T cell acute lymphoblastic leukemia cells

    Directory of Open Access Journals (Sweden)

    Lee Norman H

    2010-07-01

    Full Text Available Abstract Background The homeobox gene TLX1 (for T-cell leukemia homeobox 1, previously known as HOX11 is inappropriately expressed in a major subgroup of T cell acute lymphoblastic leukemia (T-ALL where it is strongly associated with activating NOTCH1 mutations. Despite the recognition that these genetic lesions cooperate in leukemogenesis, there have been no mechanistic studies addressing how TLX1 and NOTCH1 functionally interact to promote the leukemic phenotype. Results Global gene expression profiling after downregulation of TLX1 and inhibition of the NOTCH pathway in ALL-SIL cells revealed that TLX1 synergistically regulated more than 60% of the NOTCH-responsive genes. Structure-function analysis demonstrated that TLX1 binding to Groucho-related TLE corepressors was necessary for maximal transcriptional regulation of the NOTCH-responsive genes tested, implicating TLX1 modulation of the NOTCH-TLE regulatory network. Comparison of the dataset to publicly available biological databases indicated that the TLX1/NOTCH-coregulated genes are frequently targeted by MYC. Gain- and loss-of-function experiments confirmed that MYC was an essential mediator of TLX1/NOTCH transcriptional output and growth promotion in ALL-SIL cells, with TLX1 contributing to the NOTCH-MYC regulatory axis by posttranscriptional enhancement of MYC protein levels. Functional classification of the TLX1/NOTCH-coregulated targets also showed enrichment for genes associated with other human cancers as well as those involved in developmental processes. In particular, we found that TLX1, NOTCH and MYC coregulate CD1B and RAG1, characteristic markers of early cortical thymocytes, and that concerted downregulation of the TLX1 and NOTCH pathways resulted in their irreversible repression. Conclusions We found that TLX1 and NOTCH synergistically regulate transcription in T-ALL, at least in part via the sharing of a TLE corepressor and by augmenting expression of MYC. We conclude that

  13. Reliability assessment of a bi-material notch: Strain energy density factor approach

    Czech Academy of Sciences Publication Activity Database

    Klusák, Jan; Knésl, Zdeněk

    2010-01-01

    Roč. 53, č. 2 (2010), s. 89-93 ISSN 0167-8442 R&D Projects: GA ČR GAP108/10/2049; GA ČR GA101/08/0994 Institutional research plan: CEZ:AV0Z20410507 Keywords : crack initiation * bi-material notch * strain energy density factor Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.073, year: 2010

  14. Generic analyses for evaluation of low Charpy upper-shelf energy effects on safety margins against fracture of reactor pressure vessel materials

    International Nuclear Information System (INIS)

    Dickson, T.L.

    1993-07-01

    Appendix G to 10 CFR Part 50 requires that reactor pressure vessel beltline material maintain Charpy upper-shelf energies of no less than 50 ft-lb during the plant operating life, unless it is demonstrated in a manner approved by the Nuclear Regulatory Commission (NRC), that lower values of Charpy upper-shelf energy provide margins of safety against fracture equivalent to those in Appendix G to Section XI of the ASME Code. Analyses based on acceptance criteria and analysis methods adopted in the ASME Code Case N-512 are described herein. Additional information on material properties was provided by the NRC, Office of Nuclear Regulatory Research, Materials Engineering Branch. These cases, specified by the NRC, represent generic applications to boiling water reactor and pressurized water reactor vessels. This report is designated as HSST Report No. 140

  15. Time-dependent temper embrittlement of reactor pressure vessel steel: Correlation between microstructural evolution and mechanical properties during tempering at 650 °C

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chuanwei; Han, Lizhan; Yan, Guanghua; Liu, Qingdong; Luo, Xiaomeng; Gu, Jianfeng, E-mail: gujf@sjtu.edu.cn

    2016-11-15

    The microstructural evolution of reactor pressure vessel (RPV) steel and its effect on the mechanical properties during tempering at 650 °C were studied to reveal the time-dependent toughness and temper embrittlement. The results show that the toughening of the material should be attributed to the decomposition of the martensite/austenite constituents and uniform distribution of carbides. When the tempering duration was 5 h, the strength of the investigated steel decreased to strike a balance with the material impact toughness that reached a plateau. As the tempering duration was further increased, the material strength was slightly reduced but the material impact toughness deteriorated drastically. This time-dependent temper embrittlement is different from traditional temper embrittlement, and it can be partly attributed to the softening of the matrix and the broadening of the ferrite laths. Moreover, the dimensions and distribution of the grain carbides are the most important factors of the impact toughness. - Highlights: • The fracture mechanism of reactor pressure vessel (RPV) steels under impact load was investigated. • The Charpy V-notch impact test and the hinge model were employed for the study. • Grain boundary carbides play a key role in the impact toughness and fracture toughness. • The dependence of the deterioration of impact toughness on tempering time was analyzed for the first time.

  16. The Role of Notch Signaling Pathway in Breast Cancer Pathogenesis

    Science.gov (United States)

    2005-07-01

    breast cancer cells, I tested whether ErbB2 overexpression will cooperate with Notch in HMLE cells. While overexpression of activated Notch1 failed to...tyrosine kinase upstream of Ras normally found overexpressed in many breast cancers , also failed to transform HMLE cells. These observations suggested...cooperation between Notch1IC and ErbB2 signaling in transforming HMLE cells. Breast cancers typically do not harbor oncogenic Ras mutations; nevertheless

  17. Notch Signaling Pathway Is Activated in Motoneurons of Spinal Muscular Atrophy

    Directory of Open Access Journals (Sweden)

    Gabriel Olmos

    2013-05-01

    Full Text Available Spinal muscular atrophy (SMA is a neurodegenerative disease produced by low levels of Survival Motor Neuron (SMN protein that affects alpha motoneurons in the spinal cord. Notch signaling is a cell-cell communication system well known as a master regulator of neural development, but also with important roles in the adult central nervous system. Aberrant Notch function is associated with several developmental neurological disorders; however, the potential implication of the Notch pathway in SMA pathogenesis has not been studied yet. We report here that SMN deficiency, induced in the astroglioma cell line U87MG after lentiviral transduction with a shSMN construct, was associated with an increase in the expression of the main components of Notch signaling pathway, namely its ligands, Jagged1 and Delta1, the Notch receptor and its active intracellular form (NICD. In the SMNΔ7 mouse model of SMA we also found increased astrocyte processes positive for Jagged1 and Delta1 in intimate contact with lumbar spinal cord motoneurons. In these motoneurons an increased Notch signaling was found, as denoted by increased NICD levels and reduced expression of the proneural gene neurogenin 3, whose transcription is negatively regulated by Notch. Together, these findings may be relevant to understand some pathologic attributes of SMA motoneurons.

  18. Down-regulation of Notch-1 by γ-secretase inhibitor suppress the ...

    African Journals Online (AJOL)

    Notch-1 signaling is crucial for stem cell maintenance and in a variety of tissues. Previous research has demonstrated that Notch-1 activity plays a key role in prostate tumorigenesis. However, the function of Notch-1 signaling in tumorigenesis can be either oncogene or suppressor gene. In our paper, γ- secretase inhibitor ...

  19. Fatigue crack growth from blunt notches

    International Nuclear Information System (INIS)

    Rhodes, D.

    1982-01-01

    A number of methods have been proposed, by which the formation and early growth of fatigue cracks at blunt notches may be predicted. In this report, four methods are compared - i.e. analysis of the crack tip plastic deformation, the cyclic contour integral, δJ, the strain in a critical volume of material, and the notch root plastic strain range. It is shown that these approaches have fundamental elements in common, and that all are compatable with linear elastic fracture mechanics. Early results from a continuing experimental programme are reported. (orig.) [de

  20. Nandrolone reduces activation of Notch signaling in denervated muscle associated with increased Numb expression

    International Nuclear Information System (INIS)

    Liu, Xin-Hua; Yao, Shen; Qiao, Rui-Fang; Levine, Alice C.; Kirschenbaum, Alexander; Pan, Jiangping; Wu, Yong; Qin, Weiping; Bauman, William A.; Cardozo, Christopher P.

    2011-01-01

    Highlights: → Nerve transection increased Notch signaling in paralyzed muscle. → Nandrolone prevented denervation-induced Notch signaling. → Nandrolone induced the expression of an inhibitor of the Notch signaling, Numb. → Reduction of denervation-induced Notch signaling by nandrolone is likely through upregulation of Numb. -- Abstract: Nandrolone, an anabolic steroid, slows denervation-atrophy in rat muscle. The molecular mechanisms responsible for this effect are not well understood. Androgens and anabolic steroids activate Notch signaling in animal models of aging and thereby mitigate sarcopenia. To explore the molecular mechanisms by which nandrolone prevents denervation-atrophy, we investigated the effects of nandrolone on Notch signaling in denervated rat gastrocnemius muscle. Denervation significantly increased Notch activity reflected by elevated levels of nuclear Notch intracellular domain (NICD) and expression of Hey1 (a Notch target gene). Activation was greatest at 7 and 35 days after denervation but remained present at 56 days after denervation. Activation of Notch in denervated muscle was prevented by nandrolone associated with upregulated expression of Numb mRNA and protein. These data demonstrate that denervation activates Notch signaling, and that nandrolone abrogates this response associated with increased expression of Numb, suggesting a potential mechanism by which nandrolone reduces denervation-atrophy.

  1. Nandrolone reduces activation of Notch signaling in denervated muscle associated with increased Numb expression

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xin-Hua [Center of Excellence for the Medical Consequences of Spinal Cord Injury, James J. Peter VA Medical Center, Bronx, NY 10468 (United States); Department of Medicine, Mount Sinai School of Medicine, New York, NY 10029 (United States); Yao, Shen; Qiao, Rui-Fang; Levine, Alice C. [Department of Medicine, Mount Sinai School of Medicine, New York, NY 10029 (United States); Kirschenbaum, Alexander [Department of Urology, Mount Sinai School of Medicine, New York, NY 10029 (United States); Pan, Jiangping; Wu, Yong [Center of Excellence for the Medical Consequences of Spinal Cord Injury, James J. Peter VA Medical Center, Bronx, NY 10468 (United States); Qin, Weiping [Center of Excellence for the Medical Consequences of Spinal Cord Injury, James J. Peter VA Medical Center, Bronx, NY 10468 (United States); Department of Medicine, Mount Sinai School of Medicine, New York, NY 10029 (United States); Bauman, William A. [Center of Excellence for the Medical Consequences of Spinal Cord Injury, James J. Peter VA Medical Center, Bronx, NY 10468 (United States); Department of Medicine, Mount Sinai School of Medicine, New York, NY 10029 (United States); Rehabilitation Medicine, Mount Sinai School of Medicine, New York, NY 10029 (United States); Cardozo, Christopher P., E-mail: chris.cardozo@mssm.edu [Center of Excellence for the Medical Consequences of Spinal Cord Injury, James J. Peter VA Medical Center, Bronx, NY 10468 (United States); Department of Medicine, Mount Sinai School of Medicine, New York, NY 10029 (United States); Rehabilitation Medicine, Mount Sinai School of Medicine, New York, NY 10029 (United States)

    2011-10-14

    Highlights: {yields} Nerve transection increased Notch signaling in paralyzed muscle. {yields} Nandrolone prevented denervation-induced Notch signaling. {yields} Nandrolone induced the expression of an inhibitor of the Notch signaling, Numb. {yields} Reduction of denervation-induced Notch signaling by nandrolone is likely through upregulation of Numb. -- Abstract: Nandrolone, an anabolic steroid, slows denervation-atrophy in rat muscle. The molecular mechanisms responsible for this effect are not well understood. Androgens and anabolic steroids activate Notch signaling in animal models of aging and thereby mitigate sarcopenia. To explore the molecular mechanisms by which nandrolone prevents denervation-atrophy, we investigated the effects of nandrolone on Notch signaling in denervated rat gastrocnemius muscle. Denervation significantly increased Notch activity reflected by elevated levels of nuclear Notch intracellular domain (NICD) and expression of Hey1 (a Notch target gene). Activation was greatest at 7 and 35 days after denervation but remained present at 56 days after denervation. Activation of Notch in denervated muscle was prevented by nandrolone associated with upregulated expression of Numb mRNA and protein. These data demonstrate that denervation activates Notch signaling, and that nandrolone abrogates this response associated with increased expression of Numb, suggesting a potential mechanism by which nandrolone reduces denervation-atrophy.

  2. Exosomal lipids impact notch signaling and induce death of human pancreatic tumoral SOJ-6 cells.

    Directory of Open Access Journals (Sweden)

    Sadia Beloribi

    Full Text Available Exosomes are of increasing interest as alternative mode of cell-to-cell communication. We previously reported that exosomes secreted by human SOJ-6 pancreatic tumor cells induce (glycoprotein ligand-independent cell death and inhibit Notch-1 pathway, this latter being particularly active during carcinogenesis and in cancer stem cells. Therefore, we asked whether exosomal lipids were key-elements for cell death and hypothesized that cholesterol-rich membrane microdomains were privileged sites of exosome interactions with tumor cells. To address these questions and based on the lipid composition of exosomes from SOJ-6 cells (Ristorcelli et al. (2008 FASEB J. 22; 3358-3369 enriched in cholesterol and sphingomyelin (lipids forming liquid-ordered phase, Lo and depleted in phospholipids (lipids forming liquid-disordered phase, Ld, we designed Synthetic Exosome-Like Nanoparticles (SELN with ratios Lo/Ld from 3.0 to 6.0 framing that of SOJ-6 cell exosomes. SELN decreased tumor cell survival, the higher the Lo/Ld ratio, the lower the cell survival. This decreased survival was due to activation of cell death with inhibition of Notch pathway. FRET analyses indicated fusions/exchanges of SELN with cell membranes. Fluorescent SELN co-localized with the ganglioside GM1 then with Rab5A, markers of lipid microdomains and of early endosomes, respectively. These interactions occurred at lipid microdomains of plasma and/or endosome membranes where the Notch-1 pathway matures. We thus demonstrated a major role for lipids in interactions between SELN and tumor cells, and in the ensued cell death. To our knowledge this is the first report on such effects of lipidic nanoparticles on tumor cell behavior. This may have implications in tumor progression.

  3. Role of Notch signaling in cell-fate determination of human mammary stem/progenitor cells

    International Nuclear Information System (INIS)

    Dontu, Gabriela; Jackson, Kyle W; McNicholas, Erin; Kawamura, Mari J; Abdallah, Wissam M; Wicha, Max S

    2004-01-01

    Notch signaling has been implicated in the regulation of cell-fate decisions such as self-renewal of adult stem cells and differentiation of progenitor cells along a particular lineage. Moreover, depending on the cellular and developmental context, the Notch pathway acts as a regulator of cell survival and cell proliferation. Abnormal expression of Notch receptors has been found in different types of epithelial metaplastic lesions and neoplastic lesions, suggesting that Notch may act as a proto-oncogene. The vertebrate Notch1 and Notch4 homologs are involved in normal development of the mammary gland, and mutated forms of these genes are associated with development of mouse mammary tumors. In order to determine the role of Notch signaling in mammary cell-fate determination, we have utilized a newly described in vitro system in which mammary stem/progenitor cells can be cultured in suspension as nonadherent 'mammospheres'. Notch signaling was activated using exogenous ligands, or was inhibited using previously characterized Notch signaling antagonists. Utilizing this system, we demonstrate that Notch signaling can act on mammary stem cells to promote self-renewal and on early progenitor cells to promote their proliferation, as demonstrated by a 10-fold increase in secondary mammosphere formation upon addition of a Notch-activating DSL peptide. In addition to acting on stem cells, Notch signaling is also able to act on multipotent progenitor cells, facilitating myoepithelial lineage-specific commitment and proliferation. Stimulation of this pathway also promotes branching morphogenesis in three-dimensional Matrigel cultures. These effects are completely inhibited by a Notch4 blocking antibody or a gamma secretase inhibitor that blocks Notch processing. In contrast to the effects of Notch signaling on mammary stem/progenitor cells, modulation of this pathway has no discernable effect on fully committed, differentiated, mammary epithelial cells. These studies

  4. Droplet digital PCR analysis of NOTCH1 gene mutations in chronic lymphocytic leukemia.

    Science.gov (United States)

    Minervini, Angela; Francesco Minervini, Crescenzio; Anelli, Luisa; Zagaria, Antonella; Casieri, Paola; Coccaro, Nicoletta; Cumbo, Cosimo; Tota, Giuseppina; Impera, Luciana; Orsini, Paola; Brunetti, Claudia; Giordano, Annamaria; Specchia, Giorgina; Albano, Francesco

    2016-12-27

    In chronic lymphocytic leukemia (CLL), NOTCH1 gene mutations (NOTCH1mut) have been associated with adverse prognostic features but the independence of these as a prognostic factor is still controversial. In our study we validated a c.7541-7542delCT NOTCH1 mutation assay based on droplet digital PCR (ddPCR); we also analyzed the NOTCH1mut allelic burden, expressed as fractional abundance (FA), in 88 CLL patients at diagnosis to assess its prognostic role and made a longitudinal ddPCR analysis in 10 cases harboring NOTCH1mut to verify the FA variation over time. Our data revealed that with the ddPCR approach the incidence of NOTCH1mut in CLL was much higher (53.4%) than expected. However, longitudinal ddPCR analysis of CLL cases showed a statistically significant reduction of the NOTCH1mut FA detected at diagnosis after treatment (median FA 11.67 % vs 0.09 %, respectively, p = 0.01); the same difference, in terms of NOTCH1mut FA, was observed in the relapsed cases compared to the NOTCH1mut allelic fraction observed in patients in complete or partial remission (median FA 4.75% vs 0.43%, respectively, p = 0.007). Our study demonstrated a much higher incidence of NOTCH1mut in CLL than has previously been reported, and showed that the NOTCH1mut allelic burden evaluation by ddPCR might identify patients in need of a closer clinical follow-up during the "watch and wait" interval and after standard chemotherapy.

  5. An Investigation on the Wear Resistance and Fatigue Behaviour of Ti-6Al-4V Notched Members Coated with Hydroxyapatite Coatings

    Directory of Open Access Journals (Sweden)

    Reza H Oskouei

    2016-02-01

    Full Text Available In this study, surface properties of Ti-6Al-4V alloy coated with hydroxyapatite coatings were investigated. Wear resistance and fatigue behaviour of samples with coating thicknesses of 10 and 50 µm as well as uncoated samples were examined. Wear experiments demonstrated that the friction factor of the uncoated titanium decreased from 0.31 to 0.06, through a fluctuating trend, after 50 cycles of wear tests. However, the friction factor of both the coated samples (10 and 50 µm gradually decreased from 0.20 to 0.12 after 50 cycles. At the end of the 50th cycle, the penetration depth of the 10 and 50 µm coated samples were 7.69 and 6.06 µm, respectively. Fatigue tests showed that hydroxyapatite coatings could improve fatigue life of a notched Ti-6Al-4V member in both low and high cycle fatigue zones. It was understood, from fractography of the fracture surfaces, that the fatigue zone of the uncoated specimens was generally smaller in comparison with that of the coated specimens. No significant difference was observed between the fatigue life of coated specimens with 10 and 50 µm thicknesses.

  6. Compact microstrip bandpass filter with tunable notch

    DEFF Research Database (Denmark)

    Christensen, Silas; Zhurbenko, Vitaliy; Johansen, Tom Keinicke

    2014-01-01

    Two different designs combining a bandpass and a notch filter are developed to operate in the receiving band from 350–470 MHz. The bandpass filter is designed from a simple structure, by use of only four short circuited stubs and a half wavelength transmission line connecting the stubs. The tunable...... notch filter ensures an attenuation level of 19.3 dB to 27.3 dB in the frequency range from 360–480 MHz. The measured passband ripple of the combined filter is less than 0.5 dB, while the insertion loss for the simplest design is less than 1.7 dB only 10 MHz from the notch frequency. Even though...... the wavelength on the selected substrate (εr = 3.55) is approximately 45 cm, the outer dimensions of the final filter only measure 10×10 cm2....

  7. ALK1 signaling inhibits angiogenesis by cooperating with the Notch pathway.

    Science.gov (United States)

    Larrivée, Bruno; Prahst, Claudia; Gordon, Emma; del Toro, Raquel; Mathivet, Thomas; Duarte, Antonio; Simons, Michael; Eichmann, Anne

    2012-03-13

    Activin receptor-like kinase 1 (ALK1) is an endothelial-specific member of the TGF-β/BMP receptor family that is inactivated in patients with hereditary hemorrhagic telangiectasia (HHT). How ALK1 signaling regulates angiogenesis remains incompletely understood. Here we show that ALK1 inhibits angiogenesis by cooperating with the Notch pathway. Blocking Alk1 signaling during postnatal development in mice leads to retinal hypervascularization and the appearance of arteriovenous malformations (AVMs). Combined blockade of Alk1 and Notch signaling further exacerbates hypervascularization, whereas activation of Alk1 by its high-affinity ligand BMP9 rescues hypersprouting induced by Notch inhibition. Mechanistically, ALK1-dependent SMAD signaling synergizes with activated Notch in stalk cells to induce expression of the Notch targets HEY1 and HEY2, thereby repressing VEGF signaling, tip cell formation, and endothelial sprouting. Taken together, these results uncover a direct link between ALK1 and Notch signaling during vascular morphogenesis that may be relevant to the pathogenesis of HHT vascular lesions. Copyright © 2012 Elsevier Inc. All rights reserved.

  8. Passive notch circuit for pulsed-off compression fields

    International Nuclear Information System (INIS)

    Nunnally, W.C.

    1976-06-01

    The operation and simulated results of a passive notch circuit used to pulse off the field in a multiturn, fusion-power system, compression coil are presented. The notch circuit permits initial plasma preparation at field zero, adiabatic compression as the field returns to its initial value, and long field decay time for plasma confinement. The major advantages and disadvantages of the notch circuit are compared with those of a standard capacitor power supply system. The major advantages are that: (1) slow-rising fields can be used for adiabatic compression, (2) solid-state switches can be used because of the inherent current and voltage waveforms, and (3) long field decay times are easier to attain than with single-turn coils

  9. The Notch Signaling Pathway Is Balancing Type 1 Innate Lymphoid Cell Immune Functions

    Directory of Open Access Journals (Sweden)

    Thibaut Perchet

    2018-06-01

    Full Text Available The Notch pathway is one of the canonical signaling pathways implicated in the development of various solid tumors. During carcinogenesis, the Notch pathway dysregulation induces tumor expression of Notch receptor ligands participating to escape the immune surveillance. The Notch pathway conditions both the development and the functional regulation of lymphoid subsets. Its importance on T cell subset polarization has been documented contrary to its action on innate lymphoid cells (ILC. We aim to analyze the effect of the Notch pathway on type 1 ILC polarization and functions after disruption of the RBPJk-dependent Notch signaling cascade. Indeed, type 1 ILC comprises conventional NK (cNK cells and type 1 helper innate lymphoid cells (ILC1 that share Notch-related functional characteristics such as the IFNg secretion downstream of T-bet expression. cNK cells have strong antitumor properties. However, data are controversial concerning ILC1 functions during carcinogenesis with models showing antitumoral capacities and others reporting ILC1 inability to control tumor growth. Using various mouse models of Notch signaling pathway depletion, we analyze the effects of its absence on type 1 ILC differentiation and cytotoxic functions. We also provide clues into its role in the maintenance of immune homeostasis in tissues. We show that modulating the Notch pathway is not only acting on tumor-specific T cell activity but also on ILC immune subset functions. Hence, our study uncovers the intrinsic Notch signaling pathway in ILC1/cNK populations and their response in case of abnormal Notch ligand expression. This study help evaluating the possible side effects mediated by immune cells different from T cells, in case of multivalent forms of the Notch receptor ligand delta 1 treatments. In definitive, it should help determining the best novel combination of therapeutic strategies in case of solid tumors.

  10. The heterotaxy gene GALNT11 glycosylates Notch to orchestrate cilia type and laterality

    DEFF Research Database (Denmark)

    Boskovski, Marko T; Yuan, Shiaulou; Pedersen, Nis Borbye

    2013-01-01

    to such determination. We previously identified GALNT11 as a candidate disease gene in a patient with heterotaxy, and now demonstrate, in Xenopus tropicalis, that galnt11 activates Notch signalling. GALNT11 O-glycosylates human NOTCH1 peptides in vitro, thereby supporting a mechanism of Notch activation either...... by increasing ADAM17-mediated ectodomain shedding of the Notch receptor or by modification of specific EGF repeats. We further developed a quantitative live imaging technique for Xenopus left-right organizer cilia and show that Galnt11-mediated Notch1 signalling modulates the spatial distribution and ratio...... of motile and immotile cilia at the left-right organizer. galnt11 or notch1 depletion increases the ratio of motile cilia at the expense of immotile cilia and produces a laterality defect reminiscent of loss of the ciliary sensor Pkd2. By contrast, Notch overexpression decreases this ratio, mimicking...

  11. Jagged1 is the pathological link between Wnt and Notch pathways in colorectal cancer.

    Science.gov (United States)

    Rodilla, Verónica; Villanueva, Alberto; Obrador-Hevia, Antonia; Robert-Moreno, Alex; Fernández-Majada, Vanessa; Grilli, Andrea; López-Bigas, Nuria; Bellora, Nicolás; Albà, M Mar; Torres, Ferran; Duñach, Mireia; Sanjuan, Xavier; Gonzalez, Sara; Gridley, Thomas; Capella, Gabriel; Bigas, Anna; Espinosa, Lluís

    2009-04-14

    Notch has been linked to beta-catenin-dependent tumorigenesis; however, the mechanisms leading to Notch activation and the contribution of the Notch pathway to colorectal cancer is not yet understood. By microarray analysis, we have identified a group of genes downstream of Wnt/beta-catenin (down-regulated when blocking Wnt/beta-catenin) that are directly regulated by Notch (repressed by gamma-secretase inhibitors and up-regulated by active Notch1 in the absence of beta-catenin signaling). We demonstrate that Notch is downstream of Wnt in colorectal cancer cells through beta-catenin-mediated transcriptional activation of the Notch-ligand Jagged1. Consistently, expression of activated Notch1 partially reverts the effects of blocking Wnt/beta-catenin pathway in tumors implanted s.c. in nude mice. Crossing APC(Min/+) with Jagged1(+/Delta) mice is sufficient to significantly reduce the size of the polyps arising in the APC mutant background indicating that Notch is an essential modulator of tumorigenesis induced by nuclear beta-catenin. We show that this mechanism is operating in human tumors from Familial Adenomatous Polyposis patients. We conclude that Notch activation, accomplished by beta-catenin-mediated up-regulation of Jagged1, is required for tumorigenesis in the intestine. The Notch-specific genetic signature is sufficient to block differentiation and promote vasculogenesis in tumors whereas proliferation depends on both pathways.

  12. Effect of Grain Boundary Character Distribution on the Impact Toughness of 410NiMo Weld Metal

    DEFF Research Database (Denmark)

    Divya, M.; Das, Chitta Ranjan; Chowdhury, Sandip Ghosh

    2016-01-01

    Grain boundary character distributions in 410NiMo weld metal were studied in the as-welded, first-stage, and second-stage postweld heat treatment (PWHT) conditions, and these were correlated with the Charpy-V impact toughness values of the material. The high impact toughness values in the weld...... metal in the as-welded and first-stage PWHT conditions compared to that in the second-stage condition are attributed to the higher fraction of low-energy I pound boundaries. A higher volume fraction of retained austenite and coarser martensite after second-stage PWHT accompanied by the formation...... in the impact toughness. In addition to this, grain refinement during 4-hour PWHT in the second stage also increased the toughness of the weld metal....

  13. Effect of chemical composition on irradiation embrittlement and annealing in Ni-Cr-Mo-V reactor pressure vessel steel

    Energy Technology Data Exchange (ETDEWEB)

    Novosad, P [Czech Nuclear Society, Prague (Czech Republic)

    1994-12-31

    Results concerning copper and phosphorus influence on radiation-induced changes in the Ni-Cr-Mo-V steel mechanical properties, are presented. Correlations between different mechanical properties for steels with different chemical composition, are presented. A comparison of transition temperature shifts obtained for static and dynamic fracture toughness tests and Charpy impact tests, is discussed. Recovery of radiation hardening, measured by hardness test after isochronal annealing of steels with different compositions, is also shown. Copper content strongly affects irradiation-induced changes of mechanical properties, but phosphorus content in connection with variable copper content has only a small effect. (author). 4 refs., 4 figs., 4 tabs.

  14. Broadband notch filter design for millimeter-wave plasma diagnostics

    DEFF Research Database (Denmark)

    Furtula, Vedran; Michelsen, Poul; Leipold, Frank

    2010-01-01

    Notch filters are integrated in plasma diagnostic systems to protect millimeter-wave receivers from intensive stray radiation. Here we present a design of a notch filter with a center frequency of 140 GHz, a rejection bandwidth of ∼ 900 MHz, and a typical insertion loss below 2 dB in the passband...... of ±9 GHz. The design is based on a fundamental rectangular waveguide with eight cylindrical cavities coupled by T-junction apertures formed as thin slits. Parameters that affect the notch performance such as physical lengths and conductor materials are discussed. The excited resonance mode...

  15. Notch pathway signaling in the skin antagonizes Merkel cell development.

    Science.gov (United States)

    Logan, Gregory J; Wright, Margaret C; Kubicki, Adam C; Maricich, Stephen M

    2018-02-15

    Merkel cells are mechanosensitive skin cells derived from the epidermal lineage whose development requires expression of the basic helix-loop-helix transcription factor Atoh1. The genes and pathways involved in regulating Merkel cell development during embryogenesis are poorly understood. Notch pathway signaling antagonizes Atoh1 expression in many developing body regions, so we hypothesized that Notch signaling might inhibit Merkel cell development. We found that conditional, constitutive overexpression of the Notch intracellular domain (NICD) in mouse epidermis significantly decreased Merkel cell numbers in whisker follicles and touch domes of hairy skin. Conversely, conditional deletion of the obligate NICD binding partner RBPj in the epidermis significantly increased Merkel cell numbers in whisker follicles, led to the development of ectopic Merkel cells outside of touch domes in hairy skin epidermis, and altered the distribution of Merkel cells in touch domes. Deletion of the downstream Notch effector gene Hes1 also significantly increased Merkel cell numbers in whisker follicles. Together, these data demonstrate that Notch signaling regulates Merkel cell production and patterning. Copyright © 2018 Elsevier Inc. All rights reserved.

  16. Dangerous Liaisons: Deviant Endothelium NOTCHes toward Tumor Metastasis.

    Science.gov (United States)

    Guo, Peipei; Rafii, Shahin

    2017-03-13

    In this issue of Cancer Cell, Wieland et al. uncover a feedback loop in which tumor cells, by augmenting Notch signaling, provoke a senescent and pro-inflammatory state in endothelial cells, promoting neutrophil infiltration, tumor cell adhesion, and metastasis. Interfering with this Notch-dependent crosstalk may be a therapeutic approach to block metastasis. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Experimental analysis of compressive notch strengthening in closed-cell aluminum alloy foam

    NARCIS (Netherlands)

    Antoniou, A; Onck, PR; Bastawros, Ashraf F.

    2004-01-01

    The notch strengthening effect is studied experimentally in closed cell aluminum foams. The limit loads, net section strength were found for a set of double-edge-notched (DEN) and single-edge-notched (SEN) specimens loaded in compression. In addition, the evolution of the deformation is monitored

  18. Notch size effects on high cycle fatigue limit stress of Udimet 720

    International Nuclear Information System (INIS)

    Ren Weiju; Nicholas, Theodore

    2003-01-01

    Notch size effects on the high cycle fatigue (HCF) limit stress of Ni-base superalloy Udimet 720 were investigated on cylindrical specimens with three notch sizes of the same stress concentration factor K t =2.74. The HCF limit stress corresponding to a life of 10 6 cycles was experimentally determined at a stress ratio of 0.1 and a frequency of 25 Hz at room temperature. The stresses were calculated using finite element analysis (FEA) and the specimens analyzed using scanning electron microscopy (SEM). Test results show that at the same K t value, notch size can slightly affect the HCF limit stress of U720 when notch root plasticity occurs. FEA and SEM results reveal that the notch size effects are influenced by a complicated combination of the stress and plastic strain fields at the notch tip, the nominal stress, and the effects of prior plastic deformation on fatigue crack initiation

  19. An Evolutionary-Conserved Function of Mammalian Notch Family Members as Cell Adhesion Molecules

    Science.gov (United States)

    Murata, Akihiko; Yoshino, Miya; Hikosaka, Mari; Okuyama, Kazuki; Zhou, Lan; Sakano, Seiji; Yagita, Hideo; Hayashi, Shin-Ichi

    2014-01-01

    Notch family members were first identified as cell adhesion molecules by cell aggregation assays in Drosophila studies. However, they are generally recognized as signaling molecules, and it was unclear if their adhesion function was restricted to Drosophila. We previously demonstrated that a mouse Notch ligand, Delta-like 1 (Dll1) functioned as a cell adhesion molecule. We here investigated whether this adhesion function was conserved in the diversified mammalian Notch ligands consisted of two families, Delta-like (Dll1, Dll3 and Dll4) and Jagged (Jag1 and Jag2). The forced expression of mouse Dll1, Dll4, Jag1, and Jag2, but not Dll3, on stromal cells induced the rapid and enhanced adhesion of cultured mast cells (MCs). This was attributed to the binding of Notch1 and Notch2 on MCs to each Notch ligand on the stromal cells themselves, and not the activation of Notch signaling. Notch receptor-ligand binding strongly supported the tethering of MCs to stromal cells, the first step of cell adhesion. However, the Jag2-mediated adhesion of MCs was weaker and unlike other ligands appeared to require additional factor(s) in addition to the receptor-ligand binding. Taken together, these results demonstrated that the function of cell adhesion was conserved in mammalian as well as Drosophila Notch family members. Since Notch receptor-ligand interaction plays important roles in a broad spectrum of biological processes ranging from embryogenesis to disorders, our finding will provide a new perspective on these issues from the aspect of cell adhesion. PMID:25255288

  20. The effect of hot strip mill processing parameters and alloy addition on low temperature toughness of API-X70 steel

    Energy Technology Data Exchange (ETDEWEB)

    Ro, Kwang Seop; Al-Shammary, Saad; Al-Butairi, Adel A. [QA and PTS, SAUDI IRON and STEEL COMAPNY, Al-Jubail, (Saudi Arabia); Al-Hajeri, Khaled F. [Saudi Basic Industries Corporation, Jubail, (Saudi Arabia)

    2010-07-01

    The design of high strength steel grade is based on stringent specifications in terms of chemistry, mechanical properties and surface requirements. This study investigated the effect of alloy addition on low temperature toughness of API X70 pipeline steel. Seven different chemical compositions have been selected for experimental testing. Ni, Cr and Cu were added in various quantities to the tested material without deteriorating the phase transformation to acicular ferrite. A tensile test, Charpy impact test, DWTT pressed notch test and microstructural observations using optical microscope and SEM were carried out. Statistical analyses were done to identify the relationship between chemical composition and DWTT shear area. The following equation showed excellent agreement with the experimental test data: Pct Shear aero of DWTT (-10 degrees C) = 954 - 0.3*SRT + 0.5*TBT - 0.4*FRT + 0.04*CT - 306*C - 60*(Mn+Ni+Cu) + 38*(Mo+Cr) - 791*(Ti+Nb+V) - 4*MA. The results showed that it is possible to design high strength API X 70 steel grades with good DWTT toughness by using the statistical equation that was developed.

  1. Nuclear reactor pressure vessel integrity insurance by crack arrestability evaluation using load from CVN tests

    International Nuclear Information System (INIS)

    Fabry, A.

    1997-01-01

    The present work is undertaken in the framework of nuclear reactor pressure vessel (RPV) surveillance and aims at revisiting the crack arrest approach to structural integrity insurance. This approach, performed under normal plant operation conditions, can also offer an attractive alternative to the crack initiation philosophy promoted for accidental analysis. To this end, an accidental conservative, cost effective and robust methodology is forwarded and demonstrated: it makes use of the crack arrest information contained in the instrumented Charpy V-notch impact test and/or in the shear fracture appearance of broken samples. Particular attention is paid to the appraisal of uncertainties and the related safety margin. The resulting capability is placed in perspective with the state-of-the-art crack initiation methodology based on the slow bend testing of recracked specimens, presently under standardization world-wide. The investigation leads to highlight three conceptual weaknesses of current enfgineering and regulatory practices. Improved crack arrestability evaluation emerges as an optimal approach to insure safe PWR operation up to design end-of-life and beyond

  2. Nuclear reactor pressure vessel integrity insurance by crack arrestability evaluation using load from CVN tests

    Energy Technology Data Exchange (ETDEWEB)

    Fabry, A.

    1997-10-15

    The present work is undertaken in the framework of nuclear reactor pressure vessel (RPV) surveillance and aims at revisiting the crack arrest approach to structural integrity insurance. This approach, performed under normal plant operation conditions, can also offer an attractive alternative to the crack initiation philosophy promoted for accidental analysis. To this end, an accidental conservative, cost effective and robust methodology is forwarded and demonstrated: it makes use of the crack arrest information contained in the instrumented Charpy V-notch impact test and/or in the shear fracture appearance of broken samples. Particular attention is paid to the appraisal of uncertainties and the related safety margin. The resulting capability is placed in perspective with the state-of-the-art crack initiation methodology based on the slow bend testing of recracked specimens, presently under standardization world-wide. The investigation leads to highlight three conceptual weaknesses of current enfgineering and regulatory practices. Improved crack arrestability evaluation emerges as an optimal approach to insure safe PWR operation up to design end-of-life and beyond.

  3. Analysis of the Mechanical Behavior, Creep Resistance and Uniaxial Fatigue Strength of Martensitic Steel X46Cr13

    Science.gov (United States)

    Brnic, Josip; Krscanski, Sanjin; Lanc, Domagoj; Brcic, Marino; Turkalj, Goran; Canadija, Marko; Niu, Jitai

    2017-01-01

    The article deals with the analysis of the mechanical behavior at different temperatures, uniaxial creep and uniaxial fatigue of martensitic steel X46Cr13 (1.4034, AISI 420). For the purpose of considering the aforementioned mechanical behavior, as well as determining the appropriate resistance to creep and fatigue strength levels, numerous uniaxial tests were carried out. Tests related to mechanical properties performed at different temperatures are presented in the form of engineering stress-strain diagrams. Short-time creep tests performed at different temperatures and different stress levels are presented in the form of creep curves. Fatigue tests carried out at stress ratios R=0.25 and R=−1 are shown in the form of S–N (fatigue) diagrams. The finite fatigue regime for each of the mentioned stress ratios is modeled by an inclined log line, while the infinite fatigue regime is modeled by a horizontal line, which represents the fatigue limit of the material and previously was calculated by the modified staircase method. Finally, the fracture toughness has been calculated based on the Charpy V-notch impact energy. PMID:28772749

  4. A Notch-dependent molecular circuitry initiates pancreatic endocrine and ductal cell differentiation

    DEFF Research Database (Denmark)

    Shih, Hung Ping; Kopp, Janel L; Sandhu, Manbir

    2012-01-01

    necessitates subsequent Sox9 downregulation and evasion from Notch activity via cell-autonomous repression of Sox9 by Ngn3. If high Notch levels are maintained, endocrine progenitors retain Sox9 and undergo ductal fate conversion. Taken together, our findings establish a novel role for Notch in initiating both...

  5. Spoof surface plasmon polaritons based notch filter for ultra-wideband microwave waveguide

    DEFF Research Database (Denmark)

    Xiao, Binggang; Li, Sheng-Hua; Xiao, Sanshui

    2016-01-01

    Spoof surface plasmon polaritons based notch filter for ultra-wideband microwave waveguide is proposed. Owing to subwavelength confinement, such a filter has advantage in the structure size without sacrificing the performance. The spoof SPP based notch is introduced to suppress the WLAN and satel......Spoof surface plasmon polaritons based notch filter for ultra-wideband microwave waveguide is proposed. Owing to subwavelength confinement, such a filter has advantage in the structure size without sacrificing the performance. The spoof SPP based notch is introduced to suppress the WLAN...

  6. Lunatic fringe-mediated Notch signaling regulates adult hippocampal neural stem cell maintenance.

    Science.gov (United States)

    Semerci, Fatih; Choi, William Tin-Shing; Bajic, Aleksandar; Thakkar, Aarohi; Encinas, Juan Manuel; Depreux, Frederic; Segil, Neil; Groves, Andrew K; Maletic-Savatic, Mirjana

    2017-07-12

    Hippocampal neural stem cells (NSCs) integrate inputs from multiple sources to balance quiescence and activation. Notch signaling plays a key role during this process. Here, we report that Lunatic fringe ( Lfng), a key modifier of the Notch receptor, is selectively expressed in NSCs. Further, Lfng in NSCs and Notch ligands Delta1 and Jagged1, expressed by their progeny, together influence NSC recruitment, cell cycle duration, and terminal fate. We propose a new model in which Lfng-mediated Notch signaling enables direct communication between a NSC and its descendants, so that progeny can send feedback signals to the 'mother' cell to modify its cell cycle status. Lfng-mediated Notch signaling appears to be a key factor governing NSC quiescence, division, and fate.

  7. Tumor Architecture and Notch Signaling Modulate Drug Response in Basal Cell Carcinoma.

    Science.gov (United States)

    Eberl, Markus; Mangelberger, Doris; Swanson, Jacob B; Verhaegen, Monique E; Harms, Paul W; Frohm, Marcus L; Dlugosz, Andrzej A; Wong, Sunny Y

    2018-02-12

    Hedgehog (Hh) pathway inhibitors such as vismodegib are highly effective for treating basal cell carcinoma (BCC); however, residual tumor cells frequently persist and regenerate the primary tumor upon drug discontinuation. Here, we show that BCCs are organized into two molecularly and functionally distinct compartments. Whereas interior Hh + /Notch + suprabasal cells undergo apoptosis in response to vismodegib, peripheral Hh +++ /Notch - basal cells survive throughout treatment. Inhibiting Notch specifically promotes tumor persistence without causing drug resistance, while activating Notch is sufficient to regress already established lesions. Altogether, these findings suggest that the three-dimensional architecture of BCCs establishes a natural hierarchy of drug response in the tumor and that this hierarchy can be overcome, for better or worse, by modulating Notch. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Notch toughness variability in A542 steel used in the European Group on Fracture Jsub(1c) round robin programme

    International Nuclear Information System (INIS)

    Druce, S.G.

    1983-04-01

    The through thickness variability of toughness in a 2 1/4 Cr 1Mo steel plate used in the EGF Jsub(1c) round robin has been evaluated using the Charpy impact testing. The results indicate that the toughness properties at the mid thickness position are inferior to those +- 50 mm from this position and that a comparatively large degree of scatter is present at all depth locations. The relevance of these findings to the Jsub(1c) round robin assessment is briefly discussed. (author)

  9. The effect of residual stresses induced by prestraining on fatigue life of notched specimens

    Science.gov (United States)

    Sadeler, R.; Ozel, A.; Kaymaz, I.; Totik, Y.

    2005-06-01

    The effect of tensile prestraining-induced residual stress on the fatigue life of notched steel parts was investigated. The study was performed on AISI 4140 steel. Rotating bending fatigue tests were carried out on semicircular notched specimens with different notch radii in the as-quenched and tempered conditions. Metallography of the specimens was performed by means of light optical microscopy. The finite-element method was used to evaluate the residual stress distribution near the notch region. Fatigue tests revealed fatigue life improvement for notched specimens, which changes depending on the notch radii and applied stress. Scanning electron microscopy was used to examine the fracture surfaces of the specimens.

  10. Effect of direct quenching on the microstructure and mechanical properties of the lean-chemistry HSLA-100 steel plates

    International Nuclear Information System (INIS)

    Dhua, S.K.; Sen, S.K.

    2011-01-01

    Highlights: → Direct-quenched and tempered (DQT) steels gives better mechanical properties. → Fine Cu and Nb (C, N) precipitates enhance matrix strengthening and tempering resistance. → Boron promotes hardenability, but low temperature Charpy impact toughness gets affected. → Mechanical properties equivalent to HSLA-100 steel is achieved by directly quenched leaner chemistry alloys. - Abstract: The influence of direct quenching on structure-property behavior of lean chemistry HSLA-100 steels was studied. Two laboratory heats, one containing Cu and Nb (C:0.052, Mn:0.99, Cu:1.08, Nb:0.043, Cr:0.57, Ni:1.76, Mo:0.55 pct) and the other containing Cu, Nb and B (C:0.04, Mn:1.02, Cu:1.06, Nb:0.036, Cr:0.87, Ni:1.32, Mo:0.41, B:0.002 percent) were hot-rolled into 25 and 12.5 mm thick plates by varying finish-rolling temperatures. The plates were heat-treated by conventional reheat quenching and tempering (RQT), as well as by direct quenching and tempering (DQT) techniques. In general, direct-quench and tempered plates of Nb-Cu heat exhibited good strength (yield strength ∼ 900 MPa) and low-temperature impact toughness (average: 74 J at -85 deg. C); the Charpy V-notch impact energies were marginally lower than conventional HSLA-100 steel. In Nb-Cu-B heat, impact toughness at low-temperature was inferior owing to boron segregation at grain boundaries. Transmission electron microscopy (TEM) and scanning auger microprobe (SAM) analysis confirmed existence of borocarbides at grain boundaries in this steel. In general, for both the steels, the mechanical properties of the direct-quench and tempered plates were found to be superior to reheat quench and tempered plates. A detailed transmission electron microscopy study revealed presence of fine Cu and Nb (C, N) precipitates in these steels. It was also observed that smaller martensite inter-lath spacing, finer grains and precipitates in direct-quench and tempered plates compared to the reheat quench and tempered plates

  11. Identification of a Paralog-Specific Notch1 Intracellular Domain Degron

    OpenAIRE

    Broadus, Matthew R.; Chen, Tony W.; Neitzel, Leif R.; Ng, Victoria H.; Jodoin, Jeanne; Lee, Laura A.; Salic, Adrian; Robbins, David J.; Capobianco, Anthony J.; Patton, James G.; Huppert, Stacey S.; Lee, Ethan

    2016-01-01

    Upon Notch pathway activation, the receptor is cleaved to release the Notch intracellular domain (NICD), which translocates to the nucleus to activate gene transcription. Using Xenopus egg extracts, we have identified a Notch1-specific destruction signal (N1-Box). We show that mutations in the N1-Box inhibit NICD1 degradation and that the N1-Box is transferable for the promotion of degradation of heterologous proteins in Xenopus egg extracts and in cultured human cells. Mutation of the N1-Box...

  12. Nylon-6/rubber blends: 6. Notched tensile impact testing of nylon-6(ethylene-propylene rubber) blends

    NARCIS (Netherlands)

    Dijkstra, Krijn; Dijkstra, K.; ter Laak, J.A.; ter Laak, J.; Gaymans, R.J.

    1994-01-01

    The deformation and fracture behaviour of nylon-6/EPR (ethylene-propylene rubber) blends is studied as a function of strain rate and rubber content. Therefore, tensile experiments are conducted on notched specimens over a broad range of draw speeds (including strain rates as encountered in normal

  13. Evaluation of Notch and Hypoxia Signaling Pathways in Chemically ...

    African Journals Online (AJOL)

    Hepatocellular carcinoma (HCC) is a common worldwide malignancy. Notch signaling pathway contributes to the genesis of diverse cancers, however, its role in HCC is unclear. Hypoxia is a common feature of HCC. Signal integration between Notch and hypoxia may be involved in HCC. The aim of this study was to ...

  14. Notch sensitivity of ductile metallic foams : A computational study

    NARCIS (Netherlands)

    Mangipudi, K. R.; Onck, P. R.

    2011-01-01

    The role of notches in the fracture strength of metal foams has been studied using a multiscale model based on a two-dimensional Voronoi representation of the cellular architecture. The effect of the crack length to the specimen width ratio on the net section strength of double edge notch (DEN)

  15. Failure of a porous solid from a deep notch

    DEFF Research Database (Denmark)

    Redanz, Pia; Fleck, Norman A.; McMeeking, Robert M.

    1997-01-01

    A finite strain finite element method is used to examine the stress state near the tip of a deep notch in an elastic-plastic porous solid. The notch is loaded in mode I plane strain tension and small scale yielding is assumed. Two rate independent strain hardening material models are used...

  16. Endocardial to myocardial notch-wnt-bmp axis regulates early heart valve development.

    Directory of Open Access Journals (Sweden)

    Yidong Wang

    Full Text Available Endocardial to mesenchymal transformation (EMT is a fundamental cellular process required for heart valve formation. Notch, Wnt and Bmp pathways are known to regulate this process. To further address how these pathways coordinate in the process, we specifically disrupted Notch1 or Jagged1 in the endocardium of mouse embryonic hearts and showed that Jagged1-Notch1 signaling in the endocardium is essential for EMT and early valvular cushion formation. qPCR and RNA in situ hybridization assays reveal that endocardial Jagged1-Notch1 signaling regulates Wnt4 expression in the atrioventricular canal (AVC endocardium and Bmp2 in the AVC myocardium. Whole embryo cultures treated with Wnt4 or Wnt inhibitory factor 1 (Wif1 show that Bmp2 expression in the AVC myocardium is dependent on Wnt activity; Wnt4 also reinstates Bmp2 expression in the AVC myocardium of endocardial Notch1 null embryos. Furthermore, while both Wnt4 and Bmp2 rescue the defective EMT resulting from Notch inhibition, Wnt4 requires Bmp for its action. These results demonstrate that Jagged1-Notch1 signaling in endocardial cells induces the expression of Wnt4, which subsequently acts as a paracrine factor to upregulate Bmp2 expression in the adjacent AVC myocardium to signal EMT.

  17. Notch signaling mediates granulocyte-macrophage colony-stimulating factor priming-induced transendothelial migration of human eosinophils.

    Science.gov (United States)

    Liu, L Y; Wang, H; Xenakis, J J; Spencer, L A

    2015-07-01

    Priming with cytokines such as granulocyte-macrophage colony-stimulating factor (GM-CSF) enhances eosinophil migration and exacerbates the excessive accumulation of eosinophils within the bronchial mucosa of asthmatics. However, mechanisms that drive GM-CSF priming are incompletely understood. Notch signaling is an evolutionarily conserved pathway that regulates cellular processes, including migration, by integrating exogenous and cell-intrinsic cues. This study investigates the hypothesis that the priming-induced enhanced migration of human eosinophils requires the Notch signaling pathway. Using pan Notch inhibitors and newly developed human antibodies that specifically neutralize Notch receptor 1 activation, we investigated a role for Notch signaling in GM-CSF-primed transmigration of human blood eosinophils in vitro and in the airway accumulation of mouse eosinophils in vivo. Notch receptor 1 was constitutively active in freshly isolated human blood eosinophils, and inhibition of Notch signaling or specific blockade of Notch receptor 1 activation during GM-CSF priming impaired priming-enhanced eosinophil transendothelial migration in vitro. Inclusion of Notch signaling inhibitors during priming was associated with diminished ERK phosphorylation, and ERK-MAPK activation was required for GM-CSF priming-induced transmigration. In vivo in mice, eosinophil accumulation within allergic airways was impaired following systemic treatment with Notch inhibitor, or adoptive transfer of eosinophils treated ex vivo with Notch inhibitor. These data identify Notch signaling as an intrinsic pathway central to GM-CSF priming-induced eosinophil tissue migration. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  18. An expanded Notch-Delta model exhibiting long-range patterning and incorporating MicroRNA regulation.

    Directory of Open Access Journals (Sweden)

    Jerry S Chen

    2014-06-01

    Full Text Available Notch-Delta signaling is a fundamental cell-cell communication mechanism that governs the differentiation of many cell types. Most existing mathematical models of Notch-Delta signaling are based on a feedback loop between Notch and Delta leading to lateral inhibition of neighboring cells. These models result in a checkerboard spatial pattern whereby adjacent cells express opposing levels of Notch and Delta, leading to alternate cell fates. However, a growing body of biological evidence suggests that Notch-Delta signaling produces other patterns that are not checkerboard, and therefore a new model is needed. Here, we present an expanded Notch-Delta model that builds upon previous models, adding a local Notch activity gradient, which affects long-range patterning, and the activity of a regulatory microRNA. This model is motivated by our experiments in the ascidian Ciona intestinalis showing that the peripheral sensory neurons, whose specification is in part regulated by the coordinate activity of Notch-Delta signaling and the microRNA miR-124, exhibit a sparse spatial pattern whereby consecutive neurons may be spaced over a dozen cells apart. We perform rigorous stability and bifurcation analyses, and demonstrate that our model is able to accurately explain and reproduce the neuronal pattern in Ciona. Using Monte Carlo simulations of our model along with miR-124 transgene over-expression assays, we demonstrate that the activity of miR-124 can be incorporated into the Notch decay rate parameter of our model. Finally, we motivate the general applicability of our model to Notch-Delta signaling in other animals by providing evidence that microRNAs regulate Notch-Delta signaling in analogous cell types in other organisms, and by discussing evidence in other organisms of sparse spatial patterns in tissues where Notch-Delta signaling is active.

  19. Immunolocalization of notch signaling protein molecules in a maxillary chondrosarcoma and its recurrent tumor

    Directory of Open Access Journals (Sweden)

    Siar CH

    2010-10-01

    Full Text Available Abstract Background Notch receptors are critical determinants of cell fate in a variety of organisms. Notch signaling is involved in the chondrogenic specification of neural crest cells. Aberrant Notch activity has been implicated in numerous human diseases including cancers; however its role in chondrogenic tumors has not been clarified. Method Tissue samples from a case of primary chondrosarcoma of the maxilla and its recurrent tumor were examined immunohistochemically for Notch1-4 and their ligands (Jagged1, Jagged2 and Delta1 expression. Results Both primary and recurrent tumors were histopathologically diagnosed as conventional hyaline chondrosarcoma (WHO Grade I. Hypercellular tumor areas strongly expressed Notch3 and Jagged1 in spindle and pleomorphic cells suggesting up-regulation of these protein molecules at sites of tumor proliferation. Expression patterns were distinct with some overlap. Differentiated malignant and atypical chondrocytes demonstrated variable expression levels of Jagged1, and weak to absent staining for Notch1, 4 and Delta1. Protein immunolocalization was largely membranous and cytoplasmic, sometimes outlining the lacunae of malignant chondrocytes. Hyaline cartilage demonstrated a diffuse or granular precipitation of Jagged1 suggesting presence of soluble Jagged1 activity at sites of abnormal chondrogenesis. No immunoreactivity for the other Notch members was observed. Calcified cartilage was consistently Notch-negative indicating down-regulation of Notch with cartilage maturation. Stromal components namely endothelial cells and fibroblasts variably expressed Notch1, 3 and Jagged1 but were mildly or non-reactive for the other members. Conclusions Results indicate that Notch signaling pathway may participate in cellular differentiation and proliferation in chondrosarcoma. Findings implicate Notch3 and Jagged1 as key molecules that influence the differentiation and maturation of cells of chondrogenic lineage.

  20. Mastermind-Like 1 Is Ubiquitinated: Functional Consequences for Notch Signaling.

    Directory of Open Access Journals (Sweden)

    Mozhgan Farshbaf

    Full Text Available Early studies demonstrated the involvement of ubiquitination of the Notch intracellular domain for rapid turnover of the transcriptional complex at Notch target genes. It was shown that this ubiquitination was promoted by the co-activator Mastermind like 1 (MAML1. MAML1 also contains numerous lysine residues that may also be ubiquitinated and necessary for protein regulation. In this study, we show that over-expressed MAML1 is ubiquitinated and identify eight conserved lysine residues which are required for ubiquitination. We also show that p300 stimulates ubiquitination and that Notch inhibits ubiquitination. Furthermore, we show that a mutant MAML1 that has decreased ubiquitination shows increased output from a HES1 reporter gene assay. Therefore, we speculate that ubiquitination of MAML1 might be a mechanism to maintain low levels of the protein until needed for transcriptional activation. In summary, this study identifies that MAML1 is ubiquitinated in the absence of Notch signaling to maintain low levels of MAML1 in the cell. Our data supports the notion that a precise and tight regulation of the Notch pathway is required for this signaling pathway.

  1. Immunohistochemical expression of Notch signaling in the lining epithelium of periapical cysts.

    Science.gov (United States)

    Meliou, Eleni; Kerezoudis, Nikolaos; Tosios, Konstantinos; Lafkas, Daniel; Kiaris, Hippokratis

    2011-02-01

    In this study we evaluated the immunohistochemical expression of the receptors Notch 1 and Notch 2, the ligand Delta 1, and the transcription factors HES 1 and HES 5 in the epithelium of well-defined periapical cysts. Immunohistochemistry was carried out on 55 formalin-fixed and paraffin-embedded, well-defined periapical cysts with minimum inflammation, obtained from the archival tissue database of the Department of Oral Pathology and Surgery. Western blotting was performed to evaluate the specificity of the anti-Notch antibody and the expression of Notch signaling in 5 fresh-frozen periapical cysts. The levels of staining intensity were estimated by the performance of a semiautomated image analysis system. Descriptive statistic of mean values obtained by computerized image analysis method was performed. Immunostaining reaction of all Notch signaling components was observed in the cytoplasm and/or the cytoplasmic membrane in the majority of epithelial cells of periapical cysts. Nuclear staining was observed occasionally in all cases. Notch 2 showed strong staining in 52.83% of the cases, followed by Notch 1 (35.85%), HES 1 and HES 5 moderate staining in 72.73% and 57.69% of the cases, respectively, and Delta 1 weak staining in 58.33% of the cases. No statistical correlation was found between the antibodies and the sex or the age of the study group. Notch is an evolutionarily conserved signaling mechanism that regulates cell fate decisions during development and postnatal life in organisms as diverse as worms, flies, and humans. The present observations indicate that Notch pathway is active downstream in the lining epithelium of periapical cysts, suggesting an involvement of this pathway in periapical cyst growth and expansion. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  2. Effect of Notches on Creep-Fatigue Behavior of a P/M Nickel-Based Superalloy

    Science.gov (United States)

    Telesman, Jack; Gabb, Timothy P.; Ghosn, Louis J.; Gayda, John, Jr.

    2015-01-01

    A study was performed to determine and model the effect of high temperature dwells on notched low cycle fatigue (NLCF) and notch stress rupture behavior of a fine grain LSHR powder metallurgy (PM) nickel-based superalloy. It was shown that a 90 second dwell applied at the minimum stress (min dwell) was considerably more detrimental to the NLCF lives than similar dwell applied at the maximum stress (max dwell). The short min dwell NLCF lives were shown to be caused by growth of small oxide blisters which caused preferential cracking when coupled with high concentrated notch root stresses. The cyclic max dwell notch tests failed mostly by a creep accumulation, not by fatigue, with the crack origin shifting internally to a substantial distance away from the notch root. The classical von Mises plastic flow model was unable to match the experimental results while the hydrostatic stress profile generated using the Drucker-Prager plasticity flow model was consistent with the experimental findings. The max dwell NLCF and notch stress rupture tests exhibited substantial creep notch strengthening. The triaxial Bridgman effective stress parameter was able to account for the notch strengthening by collapsing the notched and uniform gage geometry test data into a singular grouping.

  3. Determinación de la tenacidad a la fractura de muestras de Acero 45 fundido, empleando las correlaciones entre el KIC y la energía de impacto medida en el ensayo de Charpy. // Determination of the fracture tenacity of cast Steel grade 45 samples, using th

    Directory of Open Access Journals (Sweden)

    F. Ramos Morales

    2005-05-01

    Full Text Available En el presente trabajo se determinan los valores de tenacidad a la fractura (KIC de muestras de Acero 45 fundido,empleando las correlaciones entre la tenacidad a la fractura y la energía de impacto (CVN obtenida del ensayo de Charpy.Se hace una discusión sobre las correlaciones que más se ajustan en la región de transición y en upper shelf. Se comparanlos valores obtenidos de estas correlaciones a valores de tenacidad a la fractura establecidos en la literatura.Palabras claves: Fractura, energía de impacto, acero fundido.______________________________________________________________________________Abstract.In this paper, the values of fracture toughness (KIC are determined on specimens of cast steel grade 45, using thecorrelations among the fracture toughness (KIC and the impact energy (CVN obtained from a Charpy test. A discussion ismade on the correlations that are better adjusted in the transition region and in upper shelf region. The obtained values arecompared from these correlations to values of fracture toughness (KIC settled down in the literature.Key words. Fracture, impact energy, cast steel.

  4. Asymmetric cell division and Notch signaling specify dopaminergic neurons in Drosophila.

    Directory of Open Access Journals (Sweden)

    Murni Tio

    Full Text Available In Drosophila, dopaminergic (DA neurons can be found from mid embryonic stages of development till adulthood. Despite their functional involvement in learning and memory, not much is known about the developmental as well as molecular mechanisms involved in the events of DA neuronal specification, differentiation and maturation. In this report we demonstrate that most larval DA neurons are generated during embryonic development. Furthermore, we show that loss of function (l-o-f mutations of genes of the apical complex proteins in the asymmetric cell division (ACD machinery, such as inscuteable and bazooka result in supernumerary DA neurons, whereas l-o-f mutations of genes of the basal complex proteins such as numb result in loss or reduction of DA neurons. In addition, when Notch signaling is reduced or abolished, additional DA neurons are formed and conversely, when Notch signaling is activated, less DA neurons are generated. Our data demonstrate that both ACD and Notch signaling are crucial mechanisms for DA neuronal specification. We propose a model in which ACD results in differential Notch activation in direct siblings and in this context Notch acts as a repressor for DA neuronal specification in the sibling that receives active Notch signaling. Our study provides the first link of ACD and Notch signaling in the specification of a neurotransmitter phenotype in Drosophila. Given the high degree of conservation between Drosophila and vertebrate systems, this study could be of significance to mechanisms of DA neuronal differentiation not limited to flies.

  5. Mapping Sites of O-Glycosylation and Fringe Elongation on Drosophila Notch*

    Science.gov (United States)

    Harvey, Beth M.; Rana, Nadia A.; Moss, Hillary; Leonardi, Jessica; Jafar-Nejad, Hamed; Haltiwanger, Robert S.

    2016-01-01

    Glycosylation of the Notch receptor is essential for its activity and serves as an important modulator of signaling. Three major forms of O-glycosylation are predicted to occur at consensus sites within the epidermal growth factor-like repeats in the extracellular domain of the receptor: O-fucosylation, O-glucosylation, and O-GlcNAcylation. We have performed comprehensive mass spectral analyses of these three types of O-glycosylation on Drosophila Notch produced in S2 cells and identified peptides containing all 22 predicted O-fucose sites, all 18 predicted O-glucose sites, and all 18 putative O-GlcNAc sites. Using semiquantitative mass spectral methods, we have evaluated the occupancy and relative amounts of glycans at each site. The majority of the O-fucose sites were modified to high stoichiometries. Upon expression of the β3-N-acetylglucosaminyltransferase Fringe with Notch, we observed varying degrees of elongation beyond O-fucose monosaccharide, indicating that Fringe preferentially modifies certain sites more than others. Rumi modified O-glucose sites to high stoichiometries, although elongation of the O-glucose was site-specific. Although the current putative consensus sequence for O-GlcNAcylation predicts 18 O-GlcNAc sites on Notch, we only observed apparent O-GlcNAc modification at five sites. In addition, we performed mass spectral analysis on endogenous Notch purified from Drosophila embryos and found that the glycosylation states were similar to those found on Notch from S2 cells. These data provide foundational information for future studies investigating the mechanisms of how O-glycosylation regulates Notch activity. PMID:27268051

  6. Notch signalling mediates reproductive constraint in the adult worker honeybee

    Science.gov (United States)

    Duncan, Elizabeth J.; Hyink, Otto; Dearden, Peter K.

    2016-01-01

    The hallmark of eusociality is the reproductive division of labour, in which one female caste reproduces, while reproduction is constrained in the subordinate caste. In adult worker honeybees (Apis mellifera) reproductive constraint is conditional: in the absence of the queen and brood, adult worker honeybees activate their ovaries and lay haploid male eggs. Here, we demonstrate that chemical inhibition of Notch signalling can overcome the repressive effect of queen pheromone and promote ovary activity in adult worker honeybees. We show that Notch signalling acts on the earliest stages of oogenesis and that the removal of the queen corresponds with a loss of Notch protein in the germarium. We conclude that the ancient and pleiotropic Notch signalling pathway has been co-opted into constraining reproduction in worker honeybees and we provide the first molecular mechanism directly linking ovary activity in adult worker bees with the presence of the queen. PMID:27485026

  7. Morphometric study of suprascapular notch in Indian dry scapulae with specific reference to the incidence of completely ossified superior transverse scapular ligament.

    Science.gov (United States)

    Kannan, Usha; Kannan, N S; Anbalagan, J; Rao, Sudha

    2014-03-01

    The suprascapular notch, a depression on the lateral part of the superior border of the scapula, medial to the coracoid process, is bridged by the superior transverse scapular ligament, which is sometimes ossified and the foramen which is thus completed, transmits the suprascapular nerve to the supraspinatus fossa. Variations in the morphology of suprascapular notch have been identified as one of the causes of suprascapular nerve entrapment. Rengachary et al. classified this notch into six types, based on its shape. To study morphological variations of suprascapular notch in Indian dry scapulae and to analyze the incidence of completely ossified superior transverse scapular ligament with other ethnic populations which have been cited earlier. A total of 400 human dry scapulae which were obtained from the Department of Anatomy of selected eight medical colleges were analyzed. The type of suprascapular notch was noted and it was recorded as per the description given by Rengachary et al. The results of the present study were compared with the results of previous authors in different populations. In our study, out of 400 scapulae, 40 (10%), were identified to have completely ossified superior transverse scapular ligaments. The frequencies of various types of suprascapular notches were: Type I -20%, Type II -10%, Type III -52%, Type IV -4%, Type V -4%, Type VI -10%. Since the suprascapular nerve entrapment syndrome might be caused by complete ossification of superior transverse scapular ligament with formation of suprascapular foramen and other morphometric variations of suprascapular notch, the knowledge on such variations is essential for clinicians, for making a proper diagnosis and for planning the most suitable surgical intervention.

  8. Inhibition of Notch signaling alters the phenotype of orthotopic tumors formed from glioblastoma multiforme neurosphere cells but does not hamper intracranial tumor growth regardless of endogene Notch pathway signature

    DEFF Research Database (Denmark)

    Kristoffersen, Karina; Nedergaard, Mette Kjølhede; Villingshøj, Mette

    2014-01-01

    BACKGROUND: Brain cancer stem-like cells (bCSC) are cancer cells with neural stem cell (NSC)-like properties found in the devastating brain tumor glioblastoma multiforme (GBM). bCSC are proposed a central role in tumor initiation, progression, treatment resistance and relapse and as such present...... a promising target in GBM research. The Notch signaling pathway is often deregulated in GBM and we have previously characterized GBM-derived bCSC cultures based on their expression of the Notch-1 receptor and found that it could be used as predictive marker for the effect of Notch inhibition. The aim...... of the present project was therefore to further elucidate the significance of Notch pathway activity for the tumorigenic properties of GBM-derived bCSC. METHODS: Human-derived GBM xenograft cells previously established as NSC-like neurosphere cultures were used. Notch inhibition was accomplished by exposing...

  9. Effect of lead factors on the embrittlement of RPV SA-508 cl 3 steel

    Energy Technology Data Exchange (ETDEWEB)

    Kempf, Rodolfo, E-mail: kempf@cnea.gov.ar [CNEA, Unidad Actividad Combustibles Nucleares, División Caracterización, Avda. Gral Paz 1499, C.P.B1650KNA, San Martín, Buenos Aires (Argentina); Troiani, Horacio, E-mail: troiani@cab.cnea.gov.ar [Centro Atómico Bariloche (CNEA) e Instituto Balseiro (UNCU), CONICET, Av. Bustillo 9500, CP 8400, Rio Negro (Argentina); Fortis, Ana Maria, E-mail: fortis@cnea.gov.ar [CNEA, Departamento Estructura y Comportamiento, UNSAM, Avda. Gral Paz 1499, C.P.B1650KNA, San Martín, Buenos Aires (Argentina)

    2013-03-15

    This paper presents a project to study the effect of lead factors on the mechanical behaviour of the SA-508 type 3 Reactor Pressure Vessel (RPV) steel used in the reactor under construction Atucha II in Argentina. Charpy-V notch specimens of this steel were irradiated at the RA1 experimental reactor at a temperature of 275 °C with two lead factors (186 and 93). The neutron flux was 3.71 × 10{sup 15} n m{sup −2} s{sup −1} and 1.85 × 10{sup 15} n m{sup −2} s{sup −1} (E > 1 MeV) respectively. In both cases, the fluence was 6.6 × 10{sup 21} n m{sup −2}, which is equivalent to that received by the PHWR Atucha II RPV in 10 years of full power irradiation. The results of Charpy tests revealed significant embrittlement both in the ΔT = 14 °C and ΔT = 21 °C shifts of the ductile–brittle transition temperatures (DBTT) and in the reduction of the maximum energy absorbed. This result shows that the shift of the DBTT with a lead factor of 93 is larger than that obtained with a lead factor of 186. Then, the results of irradiation in experimental reactors (MTR) with high lead factors may not be conservative with respect to the actual RPV embrittlement.

  10. AKAP200 promotes Notch stability by protecting it from Cbl/lysosome-mediated degradation in Drosophila melanogaster.

    Directory of Open Access Journals (Sweden)

    Neeta Bala Tannan

    2018-01-01

    Full Text Available AKAP200 is a Drosophila melanogaster member of the "A Kinase Associated Protein" family of scaffolding proteins, known for their role in the spatial and temporal regulation of Protein Kinase A (PKA in multiple signaling contexts. Here, we demonstrate an unexpected function of AKAP200 in promoting Notch protein stability. In Drosophila, AKAP200 loss-of-function (LOF mutants show phenotypes that resemble Notch LOF defects, including eye patterning and sensory organ specification defects. Through genetic interactions, we demonstrate that AKAP200 interacts positively with Notch in both the eye and the thorax. We further show that AKAP200 is part of a physical complex with Notch. Biochemical studies reveal that AKAP200 stabilizes endogenous Notch protein, and that it limits ubiquitination of Notch. Specifically, our genetic and biochemical evidence indicates that AKAP200 protects Notch from the E3-ubiquitin ligase Cbl, which targets Notch to the lysosomal pathway. Indeed, we demonstrate that the effect of AKAP200 on Notch levels depends on the lysosome. Interestingly, this function of AKAP200 is fully independent of its role in PKA signaling and independent of its ability to bind PKA. Taken together, our data indicate that AKAP200 is a novel tissue specific posttranslational regulator of Notch, maintaining high Notch protein levels and thus promoting Notch signaling.

  11. AKAP200 promotes Notch stability by protecting it from Cbl/lysosome-mediated degradation in Drosophila melanogaster.

    Science.gov (United States)

    Bala Tannan, Neeta; Collu, Giovanna; Humphries, Ashley C; Serysheva, Ekatherina; Weber, Ursula; Mlodzik, Marek

    2018-01-01

    AKAP200 is a Drosophila melanogaster member of the "A Kinase Associated Protein" family of scaffolding proteins, known for their role in the spatial and temporal regulation of Protein Kinase A (PKA) in multiple signaling contexts. Here, we demonstrate an unexpected function of AKAP200 in promoting Notch protein stability. In Drosophila, AKAP200 loss-of-function (LOF) mutants show phenotypes that resemble Notch LOF defects, including eye patterning and sensory organ specification defects. Through genetic interactions, we demonstrate that AKAP200 interacts positively with Notch in both the eye and the thorax. We further show that AKAP200 is part of a physical complex with Notch. Biochemical studies reveal that AKAP200 stabilizes endogenous Notch protein, and that it limits ubiquitination of Notch. Specifically, our genetic and biochemical evidence indicates that AKAP200 protects Notch from the E3-ubiquitin ligase Cbl, which targets Notch to the lysosomal pathway. Indeed, we demonstrate that the effect of AKAP200 on Notch levels depends on the lysosome. Interestingly, this function of AKAP200 is fully independent of its role in PKA signaling and independent of its ability to bind PKA. Taken together, our data indicate that AKAP200 is a novel tissue specific posttranslational regulator of Notch, maintaining high Notch protein levels and thus promoting Notch signaling.

  12. Application and validation of the notch master curve in medium and high strength structural steels

    Energy Technology Data Exchange (ETDEWEB)

    Cicero, Sergio; Garcia, Tiberio [Universidad de Cantabria, Santander (Spain); Madrazo, Virginia [PCTCAN, Santander (Spain)

    2015-10-15

    This paper applies and validates the Notch master curve in two ferritic steels with medium (steel S460M) and high (steel S690Q) strength. The Notch master curve is an engineering tool that allows the fracture resistance of notched ferritic steels operating within their corresponding ductile-to-brittle transition zone to be estimated. It combines the Master curve and the Theory of critical distances in order to take into account the temperature and the notch effect respectively, assuming that both effects are independent. The results, derived from 168 fracture tests on notched specimens, demonstrate the capability of the Notch master curve for the prediction of the fracture resistance of medium and high strength ferritic steels operating within their ductile-to-brittle transition zone and containing notches.

  13. Theoretical and experimental study of Chen chaotic system with notch filter feedback control

    International Nuclear Information System (INIS)

    Ming, Zhang Xiao; Jian-Hua, Peng; Ju-Fang, Chen

    2010-01-01

    Since the past two decades, the time delay feedback control method has attracted more and more attention in chaos control studies because of its simplicity and efficiency compared with other chaos control schemes. Recently, it has been proposed to suppress low-dimensional chaos with the notch filter feedback control method, which can be implemented in a laser system. In this work, we have analytically determined the controllable conditions for notch filter feedback controlling of Chen chaotic system in terms of the Hopf bifurcation theory. The conditions for notch filter feedback controlled Chen chaoitc system having a stable limit cycle solution are given. Meanwhile, we also analysed the Hopf bifurcation direction, which is very important for parameter settings in notch filter feedback control applications. Finally, we apply the notch filter feedback control methods to the electronic circuit experiments and numerical simulations based on the theoretical analysis. The controlling results of notch filter feedback control method well prove the feasibility and reliability of the theoretical analysis. (general)

  14. Mutations in the estrogen receptor alpha hormone binding domain promote stem cell phenotype through notch activation in breast cancer cell lines.

    Science.gov (United States)

    Gelsomino, L; Panza, S; Giordano, C; Barone, I; Gu, G; Spina, E; Catalano, S; Fuqua, S; Andò, S

    2018-04-24

    The detection of recurrent mutations affecting the hormone binding domain (HBD) of estrogen receptor alpha (ERα/ESR1) in endocrine therapy-resistant and metastatic breast cancers has prompted interest in functional characterization of these genetic alterations. Here, we explored the role of HBD-ESR1 mutations in influencing the behavior of breast cancer stem cells (BCSCs), using various BC cell lines stably expressing wild-type or mutant (Y537 N, Y537S, D538G) ERα. Compared to WT-ERα clones, mutant cells showed increased CD44 + /CD24 - ratio, mRNA levels of stemness genes, Mammosphere Forming Efficiency (MFE), Self-Renewal and migratory capabilities. Mutant clones exhibited high expression of NOTCH receptors/ligands/target genes and blockade of NOTCH signaling reduced MFE and migratory potential. Mutant BCSC activity was dependent on ERα phosphorylation at serine 118, since its inhibition decreased MFE and NOTCH4 activation only in mutant cells. Collectively, we demonstrate that the expression of HBD-ESR1 mutations may drive BC cells to acquire stem cell traits through ER/NOTCH4 interplay. We propose the early detection of HBD-ESR1 mutations as a challenge in precision medicine strategy, suggesting the development of tailored-approaches (i.e. NOTCH inhibitors) to prevent disease development and metastatic spread in BC mutant-positive patients. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. Effect of substructure on mechanical properties and fracture behavior of lath martensite in 0.1C–1.1Si–1.7Mn steel

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shengci [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhu, Guoming, E-mail: zhuguoming@ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Kang, Yonglin, E-mail: kangylin@ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

    2016-08-05

    The purpose of this study was to analyze the microstructure of lath martensite in 0.1C–1.1Si–1.7Mn (wt.%) steel and its effect on mechanical properties and fracture behavior. The microstructure was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and electron back scattering diffraction (EBSD). Charpy V-notch impact samples and compact tension (CT) samples were used to investigate the Charpy impact properties and fatigue crack growth behavior of the steel, respectively. The propagation of cleavage crack and fatigue crack were analyzed to figure out the effective grain size. The results showed that the typical hierarchical lath martensite structure contained prior austenite grains, packets, blocks and laths; packet size and block width were positively correlated to prior austenite grain size, while lath width was maintained at about 0.29 μm. Yield strength was related to prior austenite grain size, packet size and block width, and obeyed Hall–Petch relationship. Grain refinement was effective in improving the resistance to cleavage fracture by introducing barriers to crack propagation; packet boundaries and block boundaries hold similar ability to impede the propagation of crack. Paris model can well describe the FCG behavior of the investigated steel. Block width governs the effective grain size for strength, toughness and fatigue crack propagation. - Graphical abstract: Mechanical properties and fracture behavior of 0.1C–1.1Si–1.7Mn steel. - Highlights: • Hall–Petch relationship is obeyed between yield strength and martensite microstructure size. • Packet boundaries and block boundaries hold similar ability to impede the propagation of crack. • Block width is the effective grain size for strength, toughness and fatigue crack propagation.

  16. Genetic screens to identify new Notch pathway mutants in Drosophila.

    Science.gov (United States)

    Giagtzoglou, Nikolaos

    2014-01-01

    Notch signaling controls a wide range of developmental processes, including proliferation, apoptosis, and cell fate specification during both development and adult tissue homeostasis. The functional versatility of the Notch signaling pathway is tightly linked with the complexity of its regulation in different cellular contexts. To unravel the complexity of Notch signaling, it is important to identify the different components of the Notch signaling pathway. A powerful strategy to accomplish this task is based on genetic screens. Given that the developmental context of signaling is important, these screens should be customized to specific cell populations or tissues. Here, I describe how to perform F1 clonal forward genetic screens in Drosophila to identify novel components of the Notch signaling pathway. These screens combine a classical EMS (ethyl methanesulfonate) chemical mutagenesis protocol along with clonal analysis via FRT-mediated mitotic recombination. These F1 clonal screens allow rapid phenotypic screening within clones of mutant cells induced at specific developmental stages and in tissues of interest, bypassing the pleiotropic effects of isolated mutations. More importantly, since EMS mutations have been notoriously difficult to map to specific genes in the past, I briefly discuss mapping methods that allow rapid identification of the causative mutations.

  17. Inhibition of fibroblast growth by Notch1 signaling is mediated by induction of Wnt11-dependent WISP-1.

    Directory of Open Access Journals (Sweden)

    Zhao-Jun Liu

    Full Text Available Fibroblasts are an integral component of stroma and important source of growth factors and extracellular matrix (ECM. They play a prominent role in maintaining tissue homeostasis and in wound healing and tumor growth. Notch signaling regulates biological function in a variety of cells. To elucidate the physiological function of Notch signaling in fibroblasts, we ablated Notch1 in mouse (Notch1(Flox/Flox embryonic fibroblasts (MEFs. Notch1-deficient (Notch1(-/- MEFs displayed faster growth and motility rate compared to Notch1(Flox/Flox MEFs. Such phenotypic changes, however, were reversible by reconstitution of Notch1 activation via overexpression of the intracellular domain of Notch1 (NICD1 in Notch1-deficient MEFs. In contrast, constitutive activation of Notch1 signaling by introducing NICD1 into primary human dermal fibroblasts (FF2441, which caused pan-Notch activation, inhibited cell growth and motility, whereas cellular inhibition was relievable when the Notch activation was countered with dominant-negative mutant of Master-mind like 1 (DN-MAML-1. Functionally, "Notch-activated" stromal fibroblasts could inhibit tumor cell growth/invasion. Moreover, Notch activation induced expression of Wnt-induced secreted proteins-1 (WISP-1/CCN4 in FF2441 cells while deletion of Notch1 in MEFs resulted in an opposite effect. Notably, WISP-1 suppressed fibroblast proliferation, and was responsible for mediating Notch1's inhibitory effect since siRNA-mediated blockade of WISP-1 expression could relieve cell growth inhibition. Notch1-induced WISP-1 expression appeared to be Wnt11-dependent, but Wnt1-independent. Blockade of Wnt11 expression resulted in decreased WISP-1 expression and liberated Notch-induced cell growth inhibition. These findings indicated that inhibition of fibroblast proliferation by Notch pathway activation is mediated, at least in part, through regulating Wnt1-independent, but Wnt11-dependent WISP-1 expression.

  18. Notch2 transduction by feline leukemia virus in a naturally infected cat.

    Science.gov (United States)

    Watanabe, Shinya; Ito, Jumpei; Baba, Takuya; Hiratsuka, Takahiro; Kuse, Kyohei; Ochi, Haruyo; Anai, Yukari; Hisasue, Masaharu; Tsujimoto, Hajime; Nishigaki, Kazuo

    2014-04-01

    Feline leukemia virus (FeLV) induces neoplastic and nonneoplastic diseases in cats. The transduction of cellular genes by FeLV is sometimes observed and associated with neoplastic diseases including lymphoma and sarcoma. Here, we report the first natural case of feline Notch2 transduction by FeLV in an infected cat with multicentric lymphoma and hypercalcemia. We cloned recombinant FeLVs harboring Notch2 in the env gene. Notch2 was able to activate expression of a reporter gene, similar to what was previously reported in cats with experimental FeLV-induced thymic lymphoma. Our findings suggest that the transduction of Notch2 strongly correlates with FeLV-induced lymphoma.

  19. Applicability and interpretation of fracture test methods for metals

    International Nuclear Information System (INIS)

    Langford, W.J.

    1978-05-01

    Fracture tests are conducted usually out of a conviction (sometimes only vaguely defined) that they will guarantee a certain level of protecton from metal failure. Qualitative tests, such as the Charpy V-notch, produce results which cannot be rigorously related to a measure of fracture tolerance: rather, they indicate metal quality so that fracture tolerance may be inferred. Quantitative tests on the other hand provide parameters which may be used directly in equations to determine the likelihood of fracture. Both types of tests have limitations which should be understood: the paper tries to provide guidance on the relative merits of either approach for a particular purpose, and gives an insight into near-future test methods which will extend the range of usefullness of quantitative tests. (author)

  20. Identification of 11-amino acid peptides that disrupt Notch-mediated processes in Drosophila

    Directory of Open Access Journals (Sweden)

    Yeh Hsiao-Fong

    2011-06-01

    Full Text Available Abstract Background The conserved Notch signaling pathway regulates cell fate decisions and maintains stem cells in multicellular organisms. Up-regulation of Notch signaling is observed in several types of cancer and is causally involved in proliferation and survival of cancer cells. Thus, it is of great interest to look for anti-Notch reagents for therapeutic purposes. In model animal Drosophila, Notch signaling restricts selection of sensory organ precursors (SOPs during external sensory (ES organ development. To look for novel genes that can suppress Notch signaling, we performed a gain-of-function modifier screen to look for genes that enhance the phenotype of ectopic ES organs induced by overexpression of phyllopod, a gene required for SOP specification. Results From the gain-of-function screen, we discovered that overexpression of polished rice/tarsal-less (pri/tal increases the numbers of ES organs as well as SOPs. pri/tal is a polycistronic gene that contains four short open reading frames encoding three 11-amino acid and one 32-amino acid peptides. Ectopic expression of the 11 amino-acid peptides recapitulates the pri/tal misexpression phenotype in ectopic ES organ formation. In situ hybridization experiment reveals that pri/tal mRNA is expressed in the SOPs of the chemosensory organs and the stretch-sensing chordotonal organs. In Drosophila wing development, the Notch signaling pathway mediates the formation of the dorsal-ventral (DV compartmental boundary and the restriction of the vein width from the primordial veins, the proveins. We also found that pri/tal mRNA is expressed in the DV boundary and the longitudinal proveins, and overexpression of Pri/Tal peptides disrupts the DV boundary formation and helps to expand the width of the wing vein. Genetic analyses further show that a Notch loss-of-function allele strongly enhances these two phenotypes. Cut and E(splmβ are target genes of the Notch pathway in DV boundary formation and

  1. Tensile behavior of unnotched and notched tungsten--copper laminar composites

    International Nuclear Information System (INIS)

    Hoffman, C.A.

    1976-06-01

    Relations were studied between the tensile strengths of unnotched and of notched, and elastic moduli of unnotched laminar sheet or foil composites and the amounts of reinforcement. Tungsten was used as the reinforcement and copper as the matrix, and the tests were run at room temperature. Three thicknesses of tungsten (i.e., 0.00254, 0.0127, and 0.0254 cm (0.001, 0.005, and 0.010 in) were used, and the nominal volume fraction of tungsten was varied from about 0.05 to 0.95. It was found that the tensile strength of the unnotched specimens could be related to the amount of reinforcement, as could the elastic moduli, and that these values could be predicted by use of the rule of mixtures. The tensile strengths of the notched laminar composites could be predicted by use of the rule of mixtures using strengths for notched constituents, provided notch effects did not predominate. (Author)

  2. Some observations on the nature of the audiometric 4000 hz notch: data from 3430 veterans.

    Science.gov (United States)

    Wilson, Richard H

    2011-01-01

    Pure-tone, air-conduction audiograms notched at 4000 Hz have long been considered the signature configuration for noise-induced hearing loss even though there is an extensive literature that does not mesh with this simple explanation. There are many reports of notched audiograms from individuals with no history of noise exposure and, conversely, reports of audiograms with no notches from individuals with a history of noise exposure. Recent reports increasingly suggest that unilateral 4000 Hz notches are common. The prevalence of notched audiograms at 4000 Hz is dependent on the definition of the notch and the population under study. To examine the prevalence and characteristics of audiograms that are notched at 4000 Hz. Retrospective, descriptive. The participants were 3430 veterans evaluated in the Audiology Clinic at the VA Medical Center, Mountain Home, Tennessee. The mean age was 62.3 yr. Data Collection and Analyses: The data were collected in the course of a 60 min, routine audiological evaluation. In addition to pure-tone audiometry, a history, otoscopy, speech audiometry in quiet and in noise, and aural-acoustic immittance measures were included in the clinic protocol but were not evaluated in this report. A notch was defined when the 4000 Hz threshold minus the 2000 Hz threshold and the 4000 Hz threshold minus the 8000 Hz threshold both were ≥10 dB. Overall the mean LE (left ear) thresholds at 2000, 3000, and 4000 Hz were at hearing levels 2-3 dB higher than the hearing levels for the corresponding mean RE (right ear) thresholds; the differences were significant. A notched audiogram was observed in 40.6% of the participants in at least one ear with 15.4% having bilateral notches, 28.8% LE notches, and 27.1% RE notches. Unilateral 4000 Hz notches were almost twice as prevalent as bilateral 4000 Hz notches. Viewed as a function of age, notched audiograms were most common (∼35% of the participants) in the 40 and 50 yr groups with a diminishing prevalence

  3. The Hippo signaling functions through the Notch signaling to regulate intrahepatic bile duct development in mammals

    Science.gov (United States)

    Wu, Nan; Nguyen, Quy; Wan, Ying; Zhou, Tiaohao; Venter, Julie; Frampton, Gabriel A; DeMorrow, Sharon; Pan, Duojia; Meng, Fanyin; Glaser, Shannon; Alpini, Gianfranco; Bai, Haibo

    2018-01-01

    The Hippo signaling pathway and the Notch signaling pathway are evolutionary conserved signaling cascades that have important roles in embryonic development of many organs. In murine liver, disruption of either pathway impairs intrahepatic bile duct development. Recent studies suggested that the Notch signaling receptor Notch2 is a direct transcriptional target of the Hippo signaling pathway effector YAP, and the Notch signaling is a major mediator of the Hippo signaling in maintaining biliary cell characteristics in adult mice. However, it remains to be determined whether the Hippo signaling pathway functions through the Notch signaling in intrahepatic bile duct development. We found that loss of the Hippo signaling pathway tumor suppressor Nf2 resulted in increased expression levels of the Notch signaling pathway receptor Notch2 in cholangiocytes but not in hepatocytes. When knocking down Notch2 on the background of Nf2 deficiency in mouse livers, the excessive bile duct development induced by Nf2 deficiency was suppressed by heterozygous and homozygous deletion of Notch2 in a dose-dependent manner. These results implicated that Notch signaling is one of the downstream effectors of the Hippo signaling pathway in regulating intrahepatic bile duct development. PMID:28581486

  4. Planar Ultrawideband Antenna with Photonically Controlled Notched Bands

    Directory of Open Access Journals (Sweden)

    Drasko Draskovic

    2013-01-01

    Full Text Available A design of a planar microstrip-fed ultrawideband (UWB printed circular monopole antenna with optically controlled notched bands is presented. The proposed antenna is composed of a circular ultrawideband patch, with an etched T-shaped slot controlled by an integrated silicon switch. The slot modifies the frequency response of the antenna suppressing 3.5–5 GHz band when the switch is in open state. The optical switch is controlled by a low-power near-infrared (808 nm laser diode, which causes the change in the frequency response of the antenna generating a frequency notch. This solution could be expanded to include several notches in the antenna frequency response achieving a fully reconfigurable UWB antenna. The antenna could be remotely controlled at large distances using optical fiber. The prototype antenna has been fully characterized to verify these design concepts.

  5. Development of Mini-Compact Tension Test Method for Determining Fracture Toughness Master Curves for Reactor Pressure Vessel Steels

    Energy Technology Data Exchange (ETDEWEB)

    Sokolov, Mikhail A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-05-01

    Small specimens are playing the key role in evaluating properties of irradiated materials. The use of small specimens provides several advantages. Typically, only a small volume of material can be irradiated in a reactor at desirable conditions in terms of temperature, neutron flux, and neutron dose. A small volume of irradiated material may also allow for easier handling of specimens. Smaller specimens reduce the amount of radioactive material, minimizing personnel exposures and waste disposal. However, use of small specimens imposes a variety of challenges as well. These challenges are associated with proper accounting for size effects and transferability of small specimen data to the real structures of interest. Any fracture toughness specimen that can be made out of the broken halves of standard Charpy specimens may have exceptional utility for evaluation of reactor pressure vessels (RPVs) since it would allow one to determine and monitor directly actual fracture toughness instead of requiring indirect predictions using correlations established with impact data. The Charpy V-notch specimen is the most commonly used specimen geometry in surveillance programs. Validation of the mini compact tension specimen (mini-CT) geometry has been performed on previously well characterized Midland beltline Linde 80 (WF-70) weld in the unirradiated condition. It was shown that the fracture toughness transition temperature, To, measured by these Mini-CT specimens is almost the same as To value that was derived from various larger fracture toughness specimens. Moreover, an International collaborative program has been established to extend the assessment and validation efforts to irradiated Linde 80 weld metal. The program is underway and involves the Oak Ridge National Laboratory (ORNL), Central Research Institute for Electrical Power Industry (CRIEPI), and Electric Power Research Institute (EPRI). The irradiated Mini-CT specimens from broken halves of previously tested Charpy

  6. Notching of samples for fracture toughness' measurements via SEVNB Method of brittle ceramics

    International Nuclear Information System (INIS)

    Ribeiro, S.; Atilio, I.; Oliveira, M.R.; Garcia, G.C.R.; Rodrigues, J.A.

    2012-01-01

    The goal of this work is to present a notching machine to produce notches in ceramic bodies as well the choice and how to make the notches, using SiC produced by liquid phase sintering as experimental material. For the liquid sintering a mixture of Al 2 O 3 and Yb 2 O 3 as additive was applied. It was developed and built by an enterprise sited in Sao Carlos-SP an equipment, which permits to obtain polished notches in ceramic specimens to be fractured afterwards. That is to facilitate the measurement of K IC via the SEVNB method. Specimens of 10% of (Al 2 O 3 +Yb 2 O 3 ) containing SiC were sintered at 1950 deg C. Those specimens were machined and notched using razor blades and diamond pastes of 15, 9, 6, 3, 1 and 0.25 μm of particle size. The built machine to notch specimens is installed at DEMAR-EEL-USP, and it is said to be the first of that type in Brazil. The results showed that depending on the thickness of the razor blade and the size of the diamond particles, it can be curried out notches with distinct tip radius and notch depth values. (author)

  7. RBP-Jκ-dependent Notch signaling enhances retinal pigment epithelial cell proliferation in transgenic mice.

    Science.gov (United States)

    Schouwey, K; Aydin, I T; Radtke, F; Beermann, F

    2011-01-20

    The Notch signaling pathway is an ubiquitous cell-cell interaction mechanism, which is essential in controlling processes like cell proliferation, cell fate decision, differentiation or stem cell maintenance. Recent data have shown that Notch signaling is RBP-Jκ-dependent in melanocytes, being required for survival of these pigment cells that are responsible for coloration of the skin and hairs in mammals. In addition, Notch is believed to function as an oncogene in melanoma, whereas it is a tumor suppressor in mouse epidermis. In this study, we addressed the implication of the Notch signaling in the development of another population of pigment cells forming the retinal pigment epithelium (RPE) in mammalian eyes. The constitutive activity of Notch in Tyrp1::NotchIC/° transgenic mice enhanced RPE cell proliferation, and the resulting RPE-derived pigmented tumor severely affected the overall eye structure. This RPE cell proliferation is dependent on the presence of the transcription factor RBP-Jκ, as it is rescued in mice lacking RBP-Jκ in the RPE. In conclusion, Notch signaling in the RPE uses the canonical pathway, which is dependent on the transcription factor RBP-Jκ. In addition, it is of importance for RPE development, and constitutive Notch activity leads to hyperproliferation and benign tumors of these pigment cells.

  8. Stress concentration factors for an internally pressurized circular vessel containing a radial U-notch

    International Nuclear Information System (INIS)

    Carvalho, E.A. de

    2005-01-01

    This paper evaluates the stress concentration factors for an internally pressurized cylinder containing a radial U-notch along its length. This work studies the cases where the external to internal radius ratio (Ψ) is equal to 1.26, 1.52, 2.00, and 3.00 and the notch radius to internal radius ratio (Φ) is fixed and equal to 0.026. The U-notch depth varies from 0.1 to 0.6 of the wall thickness. Results are also presented for a fixed size semi-circular notch. Hoop stresses at the external wall are presented, showing regions where the stress matches the nominal one and the favourable places to install strain sensors. The finite element method is used to determine the stress concentration factors (K t ) for the above described situations and for a special case where a varying semi-circular notch is present with Ψ=3.00. This notch depth varies from 0.013 to 0.3 of the wall thickness. It is pointed out that even relatively small notches introduce large stress concentrations and disrupt the hoop stress distribution all over the cross section. Results are also compared to an example found in the literature for semi-circular notches and K t curves for both cases present the same shape

  9. Fracture toughness of A533B Part III - variability of A533B fracture toughness as determined from Charpy data

    International Nuclear Information System (INIS)

    Druce, S.G.; Eyre, B.L.

    1978-08-01

    This is the final part of a series of three reports examining the upper shelf fracture toughness of A533B Class 1 pressure vessel steel. Part I (AERE R 8968) critically reviews the current elasto plastic fracture mechanics methodologies employed to characterise toughness following extensive yielding and Part II (AERE R 8969) examines several sources of fracture mechanics data pertinent to A533B Class 1 in the longitudinal (RW) orientation. Part III is a review of the effects of (i) position and orientation within the plate (ii) welding processes and post weld heat treatment and (iii) neutron irradiation as measured by Charpy impact testing. It is concluded that the upper shelf factor energy is dependent on orientation and position and can be reduced by welding, extended post weld heat treatments and neutron irradiation. Neutron irradiation effects are known to be strongly dependent on composition and metallurgical conditions, but an explanation for the variability following extended post weld treatments has yet to be resolved. (author)

  10. Electroacupuncture pretreatment induces tolerance against focal cerebral ischemia through activation of canonical Notch pathway

    Directory of Open Access Journals (Sweden)

    Zhao Yu

    2012-09-01

    Full Text Available Abstract Background Electroacupuncture (EA pretreatment can induce the tolerance against focal cerebral ischemia. However, the underlying mechanisms have not been fully understood. Emerging evidences suggest that canonical Notch signaling may be involved in ischemic brain injury. In the present study, we tested the hypothesis that EA pretreatment-induced tolerance against focal cerebral ischemia is mediated by Notch signaling. Results EA pretreatment significantly enhanced Notch1, Notch4 and Jag1 gene transcriptions in the striatum, except Notch1 intracellular domain level, which could be increased evidently by ischemia. After ischemia and reperfusion, Hes1 mRNA and Notch1 intracellular domain level in ischemic striatum in EA pretreatment group were increased and reached the peak at 2 h and 24 h, respectively, which were both earlier than the peak achieved in control group. Intraventricular injection with the γ-secretase inhibitor MW167 attenuated the neuroprotective effect of EA pretreatment. Conclusions EA pretreatment induces the tolerance against focal cerebral ischemia through activation of canonical Notch pathway.

  11. Definition of the minimum longitude of insert in the rebuilding of Charpy test tubes for surveillance and life extension of vessels in Mexico; Definicion de la longitud minima de inserto en la reconstitucion de probetas Charpy para vigilancia y extension de vida de vasijas en Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Romero C, J.; Hernandez C, R.; Rocamontes A, M., E-mail: jesus.romero@inin.gob.mx [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2011-11-15

    In the National Institute of Nuclear Research (Mexico) a welding system for the rebuilding of Charpy test tubes has been developed, automated, qualified and used for the surveillance of the mechanical properties (mainly embrittlement) of the vessel. This system uses the halves of the rehearsed Charpy test tubes of the surveillance capsules extracted of the reactors, to obtain, of a rehearsed test tube, two reconstituted test tubes. This rebuilding process is used so much in the surveillance program like in the potential extension of the operation license of the vessel. To the halves of Charpy test tubes that have been removed the deformed part by machine are called -insert- and in a very general way the rebuilding consists in weld with the welding process -Stud Welding- two metallic implants in the ends of the insert, to obtain a reconstituted test tube. The main characteristic of this welding are the achieved small dimensions, so much of the areas welded as of the areas affected by the heat. The applicable normative settles down that the minim longitude of the insert for the welding process by Stud Welding it should be of 18 mm, however according to the same normative this longitude can diminish if is demonstrated analytic or experimentally that the central volume of 1 cm{sup 3} in the insert is not affected. In this work the measurement of the temperature profiles to different distances of the welding interface is presented, defining an equation for the maximum temperatures reached in function of the distance, on the other hand the real longitude affected in the test tube by means of metallography is determined and this way the minimum longitude of the insert for this developed rebuilding system was determined. (Author)

  12. The silent information regulator 1 (Sirt1) is a positive regulator of the Notch pathway in Drosophila

    Czech Academy of Sciences Publication Activity Database

    Horváth, Matěj; Mihajlović, Zorana; Slaninová, Věra; Perez-Gomez, Raquel; Moshkin, Y.; Krejčí, Alena

    2016-01-01

    Roč. 473, č. 22 (2016), s. 4129-4143 ISSN 0264-6021 R&D Projects: GA ČR(CZ) GA14-08583S Institutional support: RVO:60077344 Keywords : Drosophila * silent information regulator 1 * Notch pathway Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.797, year: 2016

  13. Notch activation is dispensable for D, L-sulforaphane-mediated inhibition of human prostate cancer cell migration.

    Directory of Open Access Journals (Sweden)

    Eun-Ryeong Hahm

    Full Text Available D, L-Sulforaphane (SFN, a synthetic racemic analog of broccoli constituent L-sulforaphane, is a highly promising cancer chemopreventive agent with in vivo efficacy against chemically-induced as well as oncogene-driven cancer in preclinical rodent models. Cancer chemopreventive effect of SFN is characterized by G(2/M phase cell cycle arrest, apoptosis induction, and inhibition of cell migration and invasion. Moreover, SFN inhibits multiple oncogenic signaling pathways often hyperactive in human cancers, including nuclear factor-κB, Akt, signal transducer and activator of transcription 3, and androgen receptor. The present study was designed to determine the role of Notch signaling, which is constitutively active in many human cancers, in anticancer effects of SFN using prostate cancer cells as a model. Exposure of human prostate cancer cells (PC-3, LNCaP, and/or LNCaP-C4-2B to SFN as well as its naturally-occurring thio-, sulfinyl-, and sulfonyl-analogs resulted in cleavage (activation of Notch1, Notch2, and Notch4, which was accompanied by a decrease in levels of full-length Notch forms especially at the 16- and 24-hour time points. The SFN-mediated cleavage of Notch isoforms was associated with its transcriptional activation as evidenced by RBP-Jk-, HES-1A/B- and HEY-1 luciferase reporter assays. Migration of PC-3 and LNCaP cells was decreased significantly by RNA interference of Notch1 and Notch2, but not Notch4. Furthermore, SFN-mediated inhibition of PC-3 and LNCaP cell migration was only marginally affected by knockdown of Notch1 and Notch2. Strikingly, SFN administration to Transgenic Adenocarcinoma of Mouse Prostate transgenic mice failed to increase levels of cleaved Notch1, cleaved Notch2, and HES-1 proteins in vivo in prostatic intraepithelial neoplasia, well-differentiated carcinoma or poorly-differentiated prostate cancer lesions. These results indicate that Notch activation is largely dispensable for SFN-mediated inhibition of cell

  14. Irradiation, Annealing, and Reirradiation Effects on American and Russian Reactor Pressure Vessel Steels

    International Nuclear Information System (INIS)

    Chernobaeva, A.A.; Korolev, Y.N.; Nanstad, R.K.; Nikolaev, Y.A.; Sokolov, M.A.

    1998-01-01

    One of the options to mitigate the effects of irradiation on reactor pressure vessels (RPVs) is to thermally anneal them to restore the toughness properties that have been degraded by neutron irradiation. Even though a postirradiation anneal may be deemed successful, a critical aspect of continued RPV operation is the rate of embrittlement upon reirradiation. There are insufficient data available to allow for verification of available models of reirradiation embrittlement or for the development of a reliable predictive methodology. This is especially true in the case of fracture toughness data. Under the U.S.-Russia Joint Coordinating Committee for Civilian Nuclear Reactor Safety (JCCCNRS), Working Group 3 on Radiation Embrittlement, Structural Integrity, and Life Extension of Reactor Vessels and Supports agreed to conduct a comparative study of annealing and reirradiation effects on RPV steels. The Working Group agreed that each side would irradiate, anneal, reirradiate (if feasible ), and test two materials of the other. Charpy V-notch (CVN) and tensile specimens were included. Oak Ridge National Laboratory (ORNL) conducted such a program (irradiation and annealing, including static fracture toughness) with two weld metals representative of VVER-440 and VVER-1000 RPVs, while the Russian Research Center-Kurchatov Institute (RRC-KI) conducted a program (irradiation, annealing, reirradiation, and reannealing) with Heavy-Section Steel Technology (HSST) Program Plate 02 and Heavy-Section Steel Irradiation (HSSI) Program Weld 73W. The results for each material from each laboratory are compared with those from the other laboratory. The ORNL experiments with the VVER welds included irradiation to about 1 x 10 19 n/cm 2 (>1 MeV), while the RRC-KI experiments with the U.S. materials included irradiations from about 2 to 18 x 10 19 n/cm 2 (>l MeV). In both cases, irradiations were conducted at ∼290 C and annealing treatments were conducted at ∼454 C. The ORNL and RRC

  15. Notch lineages and activity in intestinal stem cells determined by a new set of knock-in mice.

    Directory of Open Access Journals (Sweden)

    Silvia Fre

    Full Text Available The conserved role of Notch signaling in controlling intestinal cell fate specification and homeostasis has been extensively studied. Nevertheless, the precise identity of the cells in which Notch signaling is active and the role of different Notch receptor paralogues in the intestine remain ambiguous, due to the lack of reliable tools to investigate Notch expression and function in vivo. We generated a new series of transgenic mice that allowed us, by lineage analysis, to formally prove that Notch1 and Notch2 are specifically expressed in crypt stem cells. In addition, a novel Notch reporter mouse, Hes1-EmGFP(SAT, demonstrated exclusive Notch activity in crypt stem cells and absorptive progenitors. This roster of knock-in and reporter mice represents a valuable resource to functionally explore the Notch pathway in vivo in virtually all tissues.

  16. Experience with the Notch Stress Approach for Fatigue Assessment of Welded Joints

    DEFF Research Database (Denmark)

    Pedersen, Mikkel Melters; Mouritsen, Ole Ø.; Hansen, Michael Rygaard

    2010-01-01

    In this paper, fatigue assessment using the notch stress approach is discussed based on re-analysis of many fatigue test results and experience from practical application. Three topics are treated; evaluation of the fatigue strength for as-welded details (FAT225) in the notch stress system......, problems regarding assessment of mild-SCF details and a novel proposal for extension of the notch stress approach for use with post-weld treated details....

  17. Metabolic syndrome impairs notch signaling and promotes apoptosis in chronically ischemic myocardium.

    Science.gov (United States)

    Elmadhun, Nassrene Y; Sabe, Ashraf A; Lassaletta, Antonio D; Chu, Louis M; Kondra, Katelyn; Sturek, Michael; Sellke, Frank W

    2014-09-01

    Impaired angiogenesis is a known consequence of metabolic syndrome (MetS); however, the mechanism is not fully understood. Recent studies have shown that the notch signaling pathway is an integral component of cardiac angiogenesis. We tested, in a clinically relevant swine model, the effects of MetS on notch and apoptosis signaling in chronically ischemic myocardium. Ossabaw swine were fed either a regular diet (control [CTL], n = 8) or a high-cholesterol diet (MetS, n = 8) to induce MetS. An ameroid constrictor was placed to induce chronic myocardial ischemia. Eleven weeks later, the wine underwent cardiac harvest of the ischemic myocardium. Downregulation of pro-angiogenesis proteins notch2, notch4, jagged2, angiopoietin 1, and endothelial nitric oxide synthase were found in the MetS group compared with the CTL group. Also, upregulation of pro-apoptosis protein caspase 8 and downregulation of anti-angiogenesis protein phosphorylated forkhead box transcription factor 03 and pro-survival proteins phosphorylated P38 and heat shock protein 90 were present in the MetS group. Cell death was increased in the MetS group compared with the CTL group. Both CTL and MetS groups had a similar arteriolar count and capillary density, and notch3 and jagged1 were both similarly concentrated in the smooth muscle wall. MetS in chronic myocardial ischemia significantly impairs notch signaling by downregulating notch receptors, ligands, and pro-angiogenesis proteins. MetS also increases apoptosis signaling, decreases survival signaling, and increases cell death in chronically ischemic myocardium. Although short-term angiogenesis appears unaffected in this model of early MetS, the molecular signals for angiogenesis are impaired, suggesting that inhibition of notch signaling might underlie the decreased angiogenesis in later stages of MetS. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  18. Prognostic value of Notch-1 expression in hepatocellular carcinoma: a meta-analysis

    Directory of Open Access Journals (Sweden)

    Wu T

    2015-10-01

    Full Text Available Tao Wu,1 Min Jiao,1 Li Jing,1 Min-Cong Wang,1 Hai-Feng Sun,2 Qing Li,1 Yi-Yang Bai,1 Yong-Chang Wei,1 Ke-Jun Nan,1 Hui Guo1 1Department of Medical Oncology, The First Affiliated Hospital of Xi’an Jiaotong University, 2Department of Oncology, Shaanxi Cancer Hospital, Xi’an, People’s Republic of China Abstract: Association of Notch-1 expression with prognosis of patients with hepatocellular carcinoma (HCC remains controversial. We conducted a meta-analysis to reevaluate the association of Notch-1 expression with clinicopathological characteristics and prognosis of HCC. PubMed, Embase, Web of Science, and China National Knowledge Infrastructure were searched to look for relevant studies. The association between Notch-1 expression and clinicopathological parameters and overall survival (OS was then reassessed using the meta-analysis for odds ratio (OR or hazard ratio (HR and 95% confidence interval (CI. A total of seven studies, including 810 HCC patients, were eligible for the meta-analysis. Our data showed that high Notch-1 expression was able to predict poor OS (HR 1.50, 95% CI 1.17–1.83, P=0.0001. The pooled OR showed that high Notch-1 expression was significantly associated with tumor metastasis (OR 0.37, 95% CI 0.16–0.86, P=0.02 and tumor size >5 cm (OR 0.48, 95% CI 0.26–0.88, P=0.02. In contrast, there was no association between high Notch-1 expression and tumor differentiation, late TNM stage, tumor number, and portal vein invasion of HCC. In conclusion, Notch-1 overexpression might predict poorer survival and more aggressive behavior in patients with HCC. Keywords: hepatocellular carcinoma, Notch-1, prognosis, clinicopathological features, meta-analysis

  19. Damage Study in Notched Particulate Composie Specimens Under Nonuniform Strain Loading

    National Research Council Canada - National Science Library

    Kwon, Y

    1999-01-01

    .... The numerical specimen considered had a semi-circular notch with a linearly varying length. The initial crack size occurring at the notch tip was modeled and predicted using a micro/macro-approach along with a damage model...

  20. Spoof surface plasmon polaritons based notch filter for ultra-wideband microwave waveguide

    DEFF Research Database (Denmark)

    Xiao, Binggang; Li, Sheng-Hua; Xiao, Sanshui

    2016-01-01

    Spoof surface plasmon polaritons based notch filter for ultra-wideband microwave waveguide is proposed. Owing to subwavelength confinement, such a filter has advantage in the structure size without sacrificing the performance. The spoof SPP based notch is introduced to suppress the WLAN and satel...... and satellite communication signals. Due to planar structures proposed here, it is easy to integrate in the microwave integrated systems, which can play an important role in the microwave communication circuit and system.......Spoof surface plasmon polaritons based notch filter for ultra-wideband microwave waveguide is proposed. Owing to subwavelength confinement, such a filter has advantage in the structure size without sacrificing the performance. The spoof SPP based notch is introduced to suppress the WLAN...

  1. Limit load and fully plastic stress analysis for circular notched plates and bars using fully plastic analysis

    International Nuclear Information System (INIS)

    Oh, Chang Kyun; Myung, Man Sik; Kim, Yun Jae; Park, Jin Moo

    2005-01-01

    For the last four decades, tension test of notched bars has been performed to investigate the effect of stress triaxiality on ductile fracture. To quantify the effect of the notch radius on stress triaxiality, the Bridgman equation is typically used. However, recent works based on detailed finite element analysis have shown that the Bridgman equation is not correct, possibly due to his assumption that strain is constant in the necked ligament. Up to present, no systematic work has been performed on fully plastic stress fields for notched bars in tension. This paper presents fully plastic results for tension of notched bars and plates in plane strain, via finite element limit analysis. The notch radius is systematically varied, covering both un-cracked and cracked cases. Comparison of plastic limit loads with existing solutions shows that existing solutions are accurate for notched plates, but not for notched bars. Accordingly new limit load solutions are given for notched bars. Variations of stress triaxiality with the notch radius and depth are also given, which again indicates that the Bridgman solution for notched bars is not correct and inaccuracy depends on the notch radius and depth

  2. Valsartan ameliorates podocyte loss in diabetic mice through the Notch pathway.

    Science.gov (United States)

    Gao, Feng; Yao, Min; Cao, Yanping; Liu, Shuxia; Liu, Qingjuan; Duan, Huijun

    2016-05-01

    The Notch pathway is known to be linked to diabetic nephropathy (DN); however, its underlying mechanism was poorly understood. In the present study, we examined the effect of Valsartan, an angiotensin II type 1 receptor antagonist, on the Notch pathway and podocyte loss in DN. Diabetes was induced in mice by an intraperitoneal injection of streptozotocin and and this was followed by treatment with Valsartan. Levels of blood glucose, kidney weight and body weight, as well as proteinuria were measured. Samples of the kidneys were also histologically examined. The relative levels of Jagged1, Notch1, Notch intracellular domain 1 (NICD1), Hes family BHLH transcription factor 1 (Hes1) and Hes-related family BHLH transcription factor with YRPW motif 1 expression (Hey1) in the glomeruli were determined by immunohistochemical analysis, western blot analysis and RT-qPCR. The B-Cell CLL/Lymphoma 2 (Bcl-2) and p53 pathways were examined by western blot analysis. Apoptosis and detachment of podocytes from the glomerular basement membrane were examined using a TUNEL assay, flow cytometric analysis and ELISA. The number of podocytes was quantified by measuring Wilms tumor-1 (WT-1) staining. We noted that the expression of Jagged1, Notch1, NICD1, Hes1 and Hey1 was increased in a time-dependent manner in the glomeruli of mice with streptozotocin (STZ)-induced diabetes. Moreover, in diabetic mice, Valsartan significantly reduced kidney weight and proteinuria, and mitigated the pathogenic processes in the kidneys. Valsartan also inhibited the activation of Notch, Bcl-2 and p53 pathways and ameliorated podocyte loss in the glomeruli of mice with STZ-induced diabetes. Taken together, these findings indicated that Valsartan exerted a beneficial effect on reducing podocyte loss, which is associated with inhibition of Notch pathway activation in the glomeruli of diabetic mice.

  3. Fracture Mechanics Assessment for Different Notch Sizes Using Finite Element Analysis Based on Ductile Failure Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Keun Hyung; Jeon, Jun Young; Han, Jae Jun; Nam, Hyun Suk; Lee, Dae Young; Kim, Yun Jae [Korea Univ., Seoul (Korea, Republic of)

    2016-08-15

    In this study, notch defects are evaluated using fracture mechanics. To understand the effects of notch defects, FE analysis is conducted to predict the limit load and J-integral for middle-cracked and single-edge cracked plates with various sizes of notch under tension and bending. As the radius of the notch increases, the energy release rate also increases, although the limit load remains constant. The values of fracture toughness(J{sub IC}) of SM490A are determined for various notch radii through FE simulation instead of conducting an experiment. As the radius of the notch increases, the energy release rate also increases, together with a more significant increase in fracture toughness. To conclude, as the notch radius increases, the resistance to crack propagation also increases.

  4. Role of Notch signalling pathway in cancer and its association with ...

    Indian Academy of Sciences (India)

    The Notch signalling pathway is an evolutionarily conserved cell signalling pathway involved in the development of organ- ... Abnormal Notch signalling is seen in many cancers like T-cell acute ...... Morgan T. H. 1917 The theory of the gene.

  5. Control of lysosomal biogenesis and Notch-dependent tissue patterning by components of the TFEB-V-ATPase axis in Drosophila melanogaster

    DEFF Research Database (Denmark)

    Tognon, Emiliana; Kobia, Francis; Busi, Ilaria

    2016-01-01

    16-1 expression follows differentiation of proneural regions of the disc. These regions, that will form sensory organs in the adult, appear to possess a distinctive endo-lysosomal compartment and Notch (N) localization. Modulation of Mitf activity in the disc in vivo alters endo-lysosomal function...

  6. Notch signaling regulates expression of Mcl-1 and apoptosis in PPD-treated macrophages.

    Science.gov (United States)

    Palaga, Tanapat; Ratanabunyong, Siriluk; Pattarakankul, Thitiporn; Sangphech, Naunpun; Wongchana, Wipawee; Hadae, Yukihiro; Kueanjinda, Patipark

    2013-09-01

    Macrophages are cellular targets for infection by bacteria and viruses. The fate of infected macrophages plays a key role in determining the outcome of the host immune response. Apoptotic cell death of macrophages is considered to be a protective host defense that eliminates pathogens and infected cells. In this study, we investigated the involvement of Notch signaling in regulating apoptosis in macrophages treated with tuberculin purified protein derivative (PPD). Murine bone marrow-derived macrophages (BMMs) treated with PPD or infected with Mycobacterium bovis Bacillus Calmette-Guérin (BCG) induced upregulation of Notch1. This upregulation correlated well with the upregulation of the anti-apoptotic gene mcl-1 both at the transcriptional and translational levels. Decreased levels of Notch1 and Mcl-1 were observed in BMM treated with PPD when a gamma secretase inhibitor (GSI), which inhibits the processing of Notch receptors, was used. Moreover, silencing Notch1 in the macrophage-like cell line RAW264.7 decreased Mcl-1 protein expression, suggesting that Notch1 is critical for Mcl-1 expression in macrophages. A significant increase in apoptotic cells was observed upon treatment of BMM with PPD in the presence of GSI compared to the vehicle-control treated cells. Finally, analysis of the mcl-1 promoter in humans and mice revealed a conserved potential CSL/RBP-Jκ binding site. The association of Notch1 with the mcl-1 promoter was confirmed by chromatin immunoprecipitation. Taken together, these results indicate that Notch1 inhibits apoptosis of macrophages stimulated with PPD by directly controlling the mcl-1 promoter.

  7. Atypical PKC-iota Controls Stem Cell Expansion via Regulation of the Notch Pathway

    Directory of Open Access Journals (Sweden)

    In Kyoung Mah

    2015-11-01

    Full Text Available The number of stem/progenitor cells available can profoundly impact tissue homeostasis and the response to injury or disease. Here, we propose that an atypical PKC, Prkci, is a key player in regulating the switch from an expansion to a differentiation/maintenance phase via regulation of Notch, thus linking the polarity pathway with the control of stem cell self-renewal. Prkci is known to influence symmetric cell division in invertebrates; however a definitive role in mammals has not yet emerged. Using a genetic approach, we find that loss of Prkci results in a marked increase in the number of various stem/progenitor cells. The mechanism used likely involves inactivation and symmetric localization of NUMB, leading to the activation of NOTCH1 and its downstream effectors. Inhibition of atypical PKCs may be useful for boosting the production of pluripotent stem cells, multipotent stem cells, or possibly even primordial germ cells by promoting the stem cell/progenitor fate.

  8. Radiation damage in a high Ni weld

    International Nuclear Information System (INIS)

    Brumovsky, M.; Kytka, M.; Kopriva, R.

    2015-01-01

    WWER-1000 RPV weld metals are characterized by a high content of nickel, mostly about 1.7 mass % with content of manganese around 0.8 mass % with a very low copper content - about 0.05 mass %. In such material some late blooming phase effect should be observed during irradiation. Such typical weld material was irradiated in the experimental reactor LVR-15 in N RI Rez at the irradiation temperature 290 C degrees and at five neutron fluences from 1.5 to 9.5 *10 23 m -2 (E>1 MeV). Charpy V-notch impact tests, static fracture toughness tests, tensile and hardness measurement were performed to obtain effect of neutron fluence on radiation hardening as well as embrittlement. Neutron fluence dependences of all these property changes have monotonic character but with a high neutron embrittlement exponent around 0.8. Scanning electron microscope of fracture surfaces showed no or very small portion of intercrystalline fracture. Transmission electron microscopy was performed on specimens from all neutron fluences. Only low density of black-dot damage has been observed. It is assumed that most of defect are dislocation loops. The late blooming phase which may be observed from results of mechanical properties are probably below the resolution of the used JEM-2010, i.e. 1.5 nm. (authors)

  9. Statistical analyses of fracture toughness results for two irradiated high-copper welds

    International Nuclear Information System (INIS)

    Nanstad, R.K.; McCabe, D.E.; Haggag, F.M.; Bowman, K.O.; Downing, D.J.

    1990-01-01

    The objectives of the Heavy-Section Steel Irradiation Program Fifth Irradiation Series were to determine the effects of neutron irradiation on the transition temperature shift and the shape of the K Ic curve described in Sect. 6 of the ASME Boiler and Pressure Vessel Code. Two submerged-arc welds with copper contents of 0.23 and 0.31% were commercially fabricated in 215-mm-thick plates. Charpy V-notch (CVN) impact, tensile, drop-weight, and compact specimens up to 203.2 mm thick [1T, 2T, 4T, 6T, and 8T C(T)] were tested to provide a large data base for unirradiated material. Similar specimens with compacts up to 4T were irradiated at about 288 degrees C to a mean fluence of about 1.5 x 10 19 neutrons/cm 2 (>1 MeV) in the Oak Ridge Research Reactor. Both linear-elastic and elastic-plastic fracture mechanics methods were used to analyze all cleavage fracture results and local cleavage instabilities (pop-ins). Evaluation of the results showed that the cleavage fracture toughness values determined at initial pop-ins fall within the same scatter band as the values from failed specimens; thus, they were included in the data base for analysis (all data are designated K Jc )

  10. Second generation γ-secretase modulators exhibit different modulation of Notch β and Aβ production.

    Science.gov (United States)

    Wanngren, Johanna; Ottervald, Jan; Parpal, Santiago; Portelius, Erik; Strömberg, Kia; Borgegård, Tomas; Klintenberg, Rebecka; Juréus, Anders; Blomqvist, Jenny; Blennow, Kaj; Zetterberg, Henrik; Lundkvist, Johan; Rosqvist, Susanne; Karlström, Helena

    2012-09-21

    The γ-secretase complex is an appealing drug target when the therapeutic strategy is to alter amyloid-β peptide (Aβ) aggregation in Alzheimer disease. γ-Secretase is directly involved in Aβ formation and determines the pathogenic potential of Aβ by generating the aggregation-prone Aβ42 peptide. Because γ-secretase mediates cleavage of many substrates involved in cell signaling, such as the Notch receptor, it is crucial to sustain these pathways while altering the Aβ secretion. A way of avoiding interference with the physiological function of γ-secretase is to use γ-secretase modulators (GSMs) instead of inhibitors of the enzyme. GSMs modify the Aβ formation from producing the amyloid-prone Aβ42 variant to shorter and less amyloidogenic Aβ species. The modes of action of GSMs are not fully understood, and even though the pharmacology of GSMs has been thoroughly studied regarding Aβ generation, knowledge is lacking about their effects on other substrates, such as Notch. Here, using immunoprecipitation followed by MALDI-TOF MS analysis, we found that two novel, second generation GSMs modulate both Notch β and Aβ production. Moreover, by correlating S3-specific Val-1744 cleavage of Notch intracellular domain (Notch intracellular domain) to total Notch intracellular domain levels using immunocytochemistry, we also demonstrated that Notch intracellular domain is not modulated by the compounds. Interestingly, two well characterized, nonsteroidal anti-inflammatory drugs (nonsteroidal anti-inflammatory drug), R-flurbiprofen and sulindac sulfide, affect only Aβ and not Notch β formation, indicating that second generation GSMs and nonsteroidal anti-inflammatory drug-based GSMs have different modes of action regarding Notch processing.

  11. Prediction of multiaxial fatigue life for notched specimens of titanium alloy TC4

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Z. R.; Li, Z. X. [Southeast University, Nanjing (China); Hu, X. T.; Song, Y. D. [Nanjing University, Nanjing (China)

    2016-05-15

    Both the proportional and nonproportional multiaxial fatigue tests were conducted on two kinds of notched specimens of titanium alloy TC4. The multiaxial fatigue critical area of notched specimen is considered as the location experiencing the maximum damage. It is unsatisfactory to predict the multiaxial fatigue life with the local stress and strain in the fatigue critical area. The critical distance concepts are employed in the multiaxial life prediction method for notched specimens. The proposed method was checked by the test data of TC4 notched specimens. The prediction results are almost within a factor of three scatter band of the test results.

  12. Effects of mineral content on the fracture properties of equine cortical bone in double-notched beams.

    Science.gov (United States)

    McCormack, Jordan; Stover, Susan M; Gibeling, Jeffery C; Fyhrie, David P

    2012-06-01

    We recently developed a method to measure cortical bone fracture initiation toughness using a double-notched beam in four-point bending. This method was used to test the hypothesis that mineralization around the two notch roots is correlated with fracture toughness and crack extension (physical damage). Total energy absorbed to failure negatively correlated with average mineralization of the beam (r(2)=0.62), but not with notch root mineralization. Fracture initiation toughness was positively correlated to mineralization at the broken notch root (r(2)=0.34). Crack length extension at the unbroken notch was strongly negatively correlated with the average mineralization of the notch roots (r(2)=0.81) whereas crack length extension at the broken notch did not correlate with any of the mineralization measurements. Mineralization at the notch roots and the average mineralization contributed independently to the mechanical and damage properties. The data are consistent with a hypothesis that a) high notch root mineralization results in less stable crack length extension but high force to initiate unstable crack propagation while b) higher average mineralization leads to low post-yield (and total) energy absorption to failure. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Ultra-Wideband Notched Characteristic Fed by Coplanar Waveguide

    Directory of Open Access Journals (Sweden)

    Rastanto Hadinegoro

    2015-02-01

    Full Text Available In this paper, a novel Ultra-Wide Band (UWB notch patch antenna with co-planar waveguide (CPW fed is presented. This antenna only used one layer and the patch antenna is constructed on the first layer and back to back with CPW fed and bottom part is ground plane. The width notch is used to achieve the UWB characteristic. The results shown that the impedance bandwidth is 1130 MHz (1.662–2.792 GHz or about 50.7% for VSWR <2.

  14. Estimations of creep behavior and failure life for a circumferentially notched specimen

    International Nuclear Information System (INIS)

    Kobayashi, Ken-ichi; Yokobori, Toshimitsu; Kikuchi, Kenji.

    1997-01-01

    No method with which to characterize and/or illustrate total creep behavior for specimens with notches, holes or cracks has been proposed. In this paper it is proposed that most creep curves can be drawn with a master curve for each creep test whenever test conditions and failure modes are similar to each other, and the lifetime ratio normalized by the rupture time is introduced. Using smooth and circumferentially notched specimens of 2.25 Cr-1 Mo steel, creep tests were performed at 600degC for examination of this concept. Furthermore, a θ projection method was used to describe creep curves for notched specimens and to extrapolate longer creep lives. Then, the whole creep curve shape for notched specimens could be easily drawn, except for that in the vicinity of the rupture point. However, longer creep lives of notched specimens were underestimated in comparison with a simple extrapolation of the experimental data. This resulted from the negative dependence of the parameter of θ 3 on the applied stress. (author)

  15. Cryogenic treatments on AISI 420 stainless steel: Microstructure and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Prieto, G., E-mail: german.prieto@uns.edu.ar [Tribology Group, Universidad Nacional del Sur/CONICET, Av. Alem 1253, 8000 Bahía Blanca (Argentina); Ipiña, J.E. Perez [GMF UNComa/CONICET, Buenos Aires 1400, 8300 Neuquén (Argentina); Tuckart, W.R. [Tribology Group, Universidad Nacional del Sur/CONICET, Av. Alem 1253, 8000 Bahía Blanca (Argentina)

    2014-05-01

    Cryogenic treatments have been employed over the last three decades in both tool and high-alloy steels to improve wear resistance, mainly through the transformation of retained austenite and the precipitation of fine carbides. The application of these treatments to low-alloy steels and even to non-ferrous materials is becoming the subject of several investigations, due to their potentiality to reduce wear. This study was aimed at analyzing the microstructural changes and the effect of cryogenic treatments on hardness and impact toughness in martensitic AISI 420 stainless steel. X-ray diffraction (XRD) was employed for phase analysis and characterization, while carbide volume fraction, size and composition evaluation was measured by using scanning electron microscopy (SEM-EDX) and Energy Dispersive Spectrometry (EDS). Hardness was assessed with Vickers technique and the impact toughness was measured by means of Charpy's V-notch tests. Fracture surfaces were analyzed by scanning electron microscopy to evaluate the fracture micromechanisms. In this study, it has been experimentally demonstrated that cryogenic treatments favors the precipitation of small carbides, which also present a more homogeneous size distribution. It was observed that this microstructural feature is responsible for the improvement in the mechanical properties of the material.

  16. Cryogenic treatments on AISI 420 stainless steel: Microstructure and mechanical properties

    International Nuclear Information System (INIS)

    Prieto, G.; Ipiña, J.E. Perez; Tuckart, W.R.

    2014-01-01

    Cryogenic treatments have been employed over the last three decades in both tool and high-alloy steels to improve wear resistance, mainly through the transformation of retained austenite and the precipitation of fine carbides. The application of these treatments to low-alloy steels and even to non-ferrous materials is becoming the subject of several investigations, due to their potentiality to reduce wear. This study was aimed at analyzing the microstructural changes and the effect of cryogenic treatments on hardness and impact toughness in martensitic AISI 420 stainless steel. X-ray diffraction (XRD) was employed for phase analysis and characterization, while carbide volume fraction, size and composition evaluation was measured by using scanning electron microscopy (SEM-EDX) and Energy Dispersive Spectrometry (EDS). Hardness was assessed with Vickers technique and the impact toughness was measured by means of Charpy's V-notch tests. Fracture surfaces were analyzed by scanning electron microscopy to evaluate the fracture micromechanisms. In this study, it has been experimentally demonstrated that cryogenic treatments favors the precipitation of small carbides, which also present a more homogeneous size distribution. It was observed that this microstructural feature is responsible for the improvement in the mechanical properties of the material

  17. Notch Signaling and Brain Tumors

    DEFF Research Database (Denmark)

    Stockhausen, Marie; Kristoffersen, Karina; Poulsen, Hans Skovgaard

    2011-01-01

    Human brain tumors are a heterogenous group of neoplasms occurring inside the cranium and the central spinal cord. In adults and children, astrocytic glioma and medulloblastoma are the most common subtypes of primary brain tumors. These tumor types are thought to arise from cells in which Notch...

  18. Notch activates Wnt-4 signalling to control medio-lateral patterning of the pronephros.

    Science.gov (United States)

    Naylor, Richard W; Jones, Elizabeth A

    2009-11-01

    Previous studies have highlighted a role for the Notch signalling pathway during pronephrogenesis in the amphibian Xenopus laevis, and in nephron development in the mammalian metanephros, yet a mechanism for this function remains elusive. Here, we further the understanding of how Notch signalling patterns the early X. laevis pronephros anlagen, a function that might be conserved in mammalian nephron segmentation. Our results indicate that early phase pronephric Notch signalling patterns the medio-lateral axis of the dorso-anterior pronephros anlagen, permitting the glomus and tubules to develop in isolation. We show that this novel function acts through the Notch effector gene hrt1 by upregulating expression of wnt4. Wnt-4 then patterns the proximal pronephric anlagen to establish the specific compartments that span the medio-lateral axis. We also identified pronephric expression of lunatic fringe and radical fringe that is temporally and spatially appropriate for a role in regulating Notch signalling in the dorso-anterior region of the pronephros anlagen. On the basis of these results, along with data from previous publications, we propose a mechanism by which the Notch signalling pathway regulates a Wnt-4 function that patterns the proximal pronephric anlagen.

  19. Chronic Hippocampal Expression of Notch Intracellular Domain Induces Vascular Thickening, Reduces Glucose Availability, and Exacerbates Spatial Memory Deficits in a Rat Model of Early Alzheimer.

    Science.gov (United States)

    Galeano, Pablo; Leal, María C; Ferrari, Carina C; Dalmasso, María C; Martino Adami, Pamela V; Farías, María I; Casabona, Juan C; Puntel, Mariana; Do Carmo, Sonia; Smal, Clara; Arán, Martín; Castaño, Eduardo M; Pitossi, Fernando J; Cuello, A Claudio; Morelli, Laura

    2018-03-26

    The specific roles of Notch in progressive adulthood neurodegenerative disorders have begun to be unraveled in recent years. A number of independent studies have shown significant increases of Notch expression in brains from patients at later stages of sporadic Alzheimer's disease (AD). However, the impact of Notch canonical signaling activation in the pathophysiology of AD is still elusive. To further investigate this issue, 2-month-old wild-type (WT) and hemizygous McGill-R-Thy1-APP rats (Tg(+/-)) were injected in CA1 with lentiviral particles (LVP) expressing the transcriptionally active fragment of Notch, known as Notch Intracellular Domain (NICD), (LVP-NICD), or control lentivirus particles (LVP-C). The Tg(+/-) rat model captures presymptomatic aspects of the AD pathology, including intraneuronal amyloid beta (Aβ) accumulation and early cognitive deficits. Seven months after LVP administration, Morris water maze test was performed, and brains isolated for biochemical and histological analysis. Our results showed a learning impairment and a worsening of spatial memory in LVP-NICD- as compared to LVP-C-injected Tg(+/-) rats. In addition, immuno histochemistry, ELISA multiplex, Western blot, RT-qPCR, and 1 H-NMR spectrometry of cerebrospinal fluid (CSF) indicated that chronic expression of NICD promoted hippocampal vessel thickening with accumulation of Aβ in brain microvasculature, alteration of blood-brain barrier (BBB) permeability, and a decrease of CSF glucose levels. These findings suggest that, in the presence of early Aβ pathology, expression of NICD may contribute to the development of microvascular abnormalities, altering glucose transport at the BBB with impact on early decline of spatial learning and memory.

  20. Digital notch filter based active damping for LCL filters

    DEFF Research Database (Denmark)

    Yao, Wenli; Yang, Yongheng; Zhang, Xiaobin

    2015-01-01

    . In contrast, the active damping does not require any dissipation elements, and thus has become of increasing interest. As a result, a vast of active damping solutions have been reported, among which multi-loop control systems and additional sensors are necessary, leading to increased cost and complexity....... In this paper, a notch filter based active damping without the requirement of additional sensors is proposed, where the inverter current is employed as the feedback variable. Firstly, a design method of the notch filter for active damping is presented. The entire system stability has then been investigated...... in the z-domain. Simulations and experiments are carried out to verify the proposed active damping method. Both results have confirmed that the notch filter based active damping can ensure the entire system stability in the case of resonances with a good system performance....

  1. Notch and hydrogen effects on sensitized 21-6-9 stainless steel

    International Nuclear Information System (INIS)

    Caskey, C.R. Jr.

    1979-01-01

    Type 21-6-9 stainless steel alloy is slightly notch sensitive in the solution annealed condition, a behavior that is aggravated by sensitization anneal at 920 0 K. The lower toughness of the sensitized alloy is a measure of microstructural embrittlement associated with carbide precipitation in grain boundaries. The tendency toward grain boundary fracture in the sensitized alloy is accentuated by stress concentration at the notch. Also, there is an increase in notch sensitivity when the alloy is tested in a high pressure (69 MPa) hydrogen environment, due to susceptibility of the grain boundaries to hydrogen embrittlement

  2. Thermally induced high frequency random amplitude fatigue damage at sharp notches

    International Nuclear Information System (INIS)

    Lewis, M.W.J.

    1992-01-01

    Experiments have been performed using the SUPERSOMITE facility to investigate the initiation and growth of fatigue cracks at the tips of sharp surface notches subjected to random thermally-induced stress. The experimental situation is complex involving plasticity, random amplitude loading and heat transfer medium/surface coupling. Crack initiation and growth prediction have been considered using the Creager and Neuber methods to compute the strain ranges in the vicinity of the notch root. Good agreement has been obtained between the experimental results and theoretical predictions. The paper reports the results of the analysis of the notch behavior

  3. Nrf2 and Notch Signaling in Lung Cancer: Near the Crossroad

    Directory of Open Access Journals (Sweden)

    Angelo Sparaneo

    2016-01-01

    Full Text Available The transcription factor Nrf2 (NF-E2 related factor 2 is a master regulator of the cell antioxidant response associated with tumor growth and resistance to cytotoxic treatments. In particular, Nrf2 induces upregulation of cytoprotective genes by interacting with the closely situated AREs (Antioxidant Response Elements in response to endogenous or exogenous stress stimuli and takes part to several oncogenic signaling pathways. Among these, the crosstalk with Notch pathway has been shown to enhance cytoprotection and maintenance of cellular homeostasis, tissue organization by modulating cell proliferation kinetics, and stem cell self-renewal in several organs. The role of Notch and Nrf2 related pathways in tumorigenesis is highly variable and when they are both abnormally activated they can synergistically cause neoplastic proliferation by promoting cell survival, differentiation, invasion, and metastases. NFE2L2, KEAP1, and NOTCH genes family appear in the list of significantly mutated genes in tumors in both combined and individual sets, supporting the crucial role that the aberrant Nrf2-Notch crosstalk might have in cancerogenesis. In this review, we summarize current knowledge about the alterations of Nrf2 and Notch pathways and their reciprocal transcriptional regulation throughout tumorigenesis and progression of lung tumors, supporting the potentiality of putative biomarkers and therapeutic targets.

  4. Mechano sorptive behaviour of notched beams in bending

    DEFF Research Database (Denmark)

    Jensen, Signe Kamp; Hoffmeyer, Preben

    1996-01-01

    Short term bending tests with end-notched beams at constant or varying moisture content have shown an apparent contradictory dependency between moisture content and strength. The higher the moisture content the higher the strength. Varying moisture results in particularly significant differences...... and by neglecting deformation due to shear. Compression stresses perpendicular to grain in excess of 6 MPa were found in the vicinity of the notch following a period of adsorption. Similarly, small tension stresses of the order 1 MPa were registered in this area when the specimens were at their most dry condition...

  5. Overexpression of protein O-fucosyltransferase 1 accelerates hepatocellular carcinoma progression via the Notch signaling pathway

    International Nuclear Information System (INIS)

    Ma, Lijie; Dong, Pingping; Liu, Longzi; Gao, Qiang; Duan, Meng; Zhang, Si; Chen, She; Xue, Ruyi; Wang, Xiaoying

    2016-01-01

    Aberrant activation of Notch signaling frequently occurs in liver cancer, and is associated with liver malignancies. However, the mechanisms regulating pathologic Notch activation in hepatocellular carcinoma (HCC) remain unclear. Protein O-fucosyltransferase 1 (Pofut1) catalyzes the addition of O-linked fucose to the epidermal growth factor-like repeats of Notch. In the present study, we detected the expression of Pofut1 in 8 HCC cell lines and 253 human HCC tissues. We reported that Pofut1 was overexpressed in HCC cell lines and clinical HCC tissues, and Pofut1 overexpression clinically correlated with the unfavorable survival and high disease recurrence in HCC. The in vitro assay demonstrated that Pofut1 overexpression accelerated the cell proliferation and migration in HCC cells. Furthermore, Pofut1 overexpression promoted the binding of Notch ligand Dll1 to Notch receptor, and hence activated Notch signaling pathway in HCC cells, indicating that Pofut1 overexpression could be a reason for the aberrant activation of Notch signaling in HCC. Taken together, our findings indicated that an aberrant activated Pofut1-Notch pathway was involved in HCC progression, and blockage of this pathway could be a promising strategy for the therapy of HCC. - Highlights: • Pofut1 overexpression in HCC was correlated with aggressive tumor behaviors. • Pofut1 overexpression in HCC was associated with poor prognosis. • Pofut1 promoted cell proliferation, migration and invasion in hepatoma cells. • Pofut1 activated Notch signaling pathway in hepatoma cells.

  6. Overexpression of protein O-fucosyltransferase 1 accelerates hepatocellular carcinoma progression via the Notch signaling pathway

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Lijie [Liver Surgery Department, Liver Cancer Institute, Zhongshan Hospital, Fudan University, Key Laboratory of Carcinogenesis and Cancer Invasion, Ministry of Education, Shanghai (China); Dong, Pingping [Department of Gastroenterology and Hepatology, Shanghai Institute of Liver Diseases, Zhongshan Hospital of Fudan University, Shanghai (China); Liu, Longzi; Gao, Qiang; Duan, Meng [Liver Surgery Department, Liver Cancer Institute, Zhongshan Hospital, Fudan University, Key Laboratory of Carcinogenesis and Cancer Invasion, Ministry of Education, Shanghai (China); Zhang, Si; Chen, She [Key Laboratory of Glycoconjugate Research Ministry of Public Health, Department of Biochemistry and Molecular Biology, Shanghai Medical College, Fudan University, Shanghai (China); Xue, Ruyi, E-mail: xue.ruyi@zs-hospital.sh.cn [Department of Gastroenterology and Hepatology, Shanghai Institute of Liver Diseases, Zhongshan Hospital of Fudan University, Shanghai (China); Wang, Xiaoying, E-mail: xiaoyingwang@fudan.edu.cn [Liver Surgery Department, Liver Cancer Institute, Zhongshan Hospital, Fudan University, Key Laboratory of Carcinogenesis and Cancer Invasion, Ministry of Education, Shanghai (China)

    2016-04-29

    Aberrant activation of Notch signaling frequently occurs in liver cancer, and is associated with liver malignancies. However, the mechanisms regulating pathologic Notch activation in hepatocellular carcinoma (HCC) remain unclear. Protein O-fucosyltransferase 1 (Pofut1) catalyzes the addition of O-linked fucose to the epidermal growth factor-like repeats of Notch. In the present study, we detected the expression of Pofut1 in 8 HCC cell lines and 253 human HCC tissues. We reported that Pofut1 was overexpressed in HCC cell lines and clinical HCC tissues, and Pofut1 overexpression clinically correlated with the unfavorable survival and high disease recurrence in HCC. The in vitro assay demonstrated that Pofut1 overexpression accelerated the cell proliferation and migration in HCC cells. Furthermore, Pofut1 overexpression promoted the binding of Notch ligand Dll1 to Notch receptor, and hence activated Notch signaling pathway in HCC cells, indicating that Pofut1 overexpression could be a reason for the aberrant activation of Notch signaling in HCC. Taken together, our findings indicated that an aberrant activated Pofut1-Notch pathway was involved in HCC progression, and blockage of this pathway could be a promising strategy for the therapy of HCC. - Highlights: • Pofut1 overexpression in HCC was correlated with aggressive tumor behaviors. • Pofut1 overexpression in HCC was associated with poor prognosis. • Pofut1 promoted cell proliferation, migration and invasion in hepatoma cells. • Pofut1 activated Notch signaling pathway in hepatoma cells.

  7. Constitutively active Notch1 induces growth arrest of HPV-positive cervical cancer cells via separate signaling pathways

    International Nuclear Information System (INIS)

    Talora, Claudio; Cialfi, Samantha; Segatto, Oreste; Morrone, Stefania; Kim Choi, John; Frati, Luigi; Paolo Dotto, Gian; Gulino, Alberto; Screpanti, Isabella

    2005-01-01

    Notch signaling plays a key role in cell-fate determination and differentiation in different organisms and cell types. Several reports suggest that Notch signaling may be involved in neoplastic transformation. However, in primary keratinocytes, Notch1 can function as a tumor suppressor. Similarly, in HPV-positive cervical cancer cells, constitutively active Notch1 signaling was found to cause growth suppression. Activated Notch1 in these cells represses viral E6/E7 expression through AP-1 down-modulation, resulting in increased p53 expression and a block of pRb hyperphosphorylation. Here we show that in cervical cancer cell lines in which Notch1 ability to repress AP-1 activity is impaired, Notch1-enforced expression elicits an alternative pathway leading to growth arrest. Indeed, activated Notch1 signaling suppresses activity of the helix-loop-helix transcription factor E47, via ERK1/2 activation, resulting in inhibition of cell cycle progression. Moreover, we found that RBP-Jκ-dependent Notch signaling is specifically repressed in cervical cancer cells and this repression could provide one such mechanism that needs to be activated for cervical carcinogenesis. Finally, we show that inhibition of endogenous Notch1 signaling, although results in a proliferative advantage, sensitizes cervical cancer cell lines to drug-induced apoptosis. Together, our results provide novel molecular insights into Notch1-dependent growth inhibitory effects, counteracting the transforming potential of HPV

  8. Evidence of Aortopathy in Mice with Haploinsufficiency of Notch1 in Nos3-Null Background

    Directory of Open Access Journals (Sweden)

    Sara N. Koenig

    2015-03-01

    Full Text Available Thoracic aortic aneurysms (TAA are a significant cause of morbidity and mortality in humans. While the exact etiology is unknown, genetic factors play an important role. Mutations in NOTCH1 have been linked to bicuspid aortic valve (BAV and aortopathy in humans. The aim of this study was to determine if haploinsufficiency of Notch1 contributes to aortopathy using Notch1+/−; Nos3−/− mice. Echocardiographic analysis of Notch1+/−; Nos3−/− mice reveals effacement of the sinotubular junction and a trend toward dilation of the aortic sinus. Furthermore, examination of the proximal aorta of Notch1+/−; Nos3−/− mice reveals elastic fiber degradation, a trend toward increased matrix metalloproteinase 2 expression, and increased smooth muscle cell apoptosis, features characteristic of aneurysmal disease. Although at a lower penetrance, we also found features consistent with aortopathic changes in Notch1 heterozygote mice and in Nos3-null mice. Our findings implicate a novel role for Notch1 in aortopathy of the proximal aorta.

  9. Acoustic emission during tensile deformation and fracture of nuclear grade AISI type 304 stainless steel specimens with notches

    International Nuclear Information System (INIS)

    Mukhopadhyay, C.K.; Jayakumar, T.; Baldev Raj

    1996-01-01

    Acoustic emission generated during tensile deformation and fracture of nuclear grade AISI type 304 stainless steel specimens with notches has been studied. The extent of acoustic activity generated depends on notch tip severity, notch tip blunting and tearing of the notches. The equation N=AK m applied to the acoustic emission data of the notched specimens has shown good correlation. Acoustic emission technique can be used to estimate the size of an unknown notch. (author)

  10. Recent improvements in size effects correlations for DBTT and upper shelf energy of ferritic steels

    International Nuclear Information System (INIS)

    Kumar, A.S.; Louden, B.S.; Garner, F.A.; Hamilton, M.L.

    1992-01-01

    Currently available correlations for the effects of specimen size on the USE were developed for relatively ductile steels and will not serve as well when the steels become embrittled. Size effects correlations were developed recently for the impact properties of less ductile HT9 to be applied to other initially more ductile steels as they lose their ductility during irradiation. These new correlations successfully predict the ductile brittle transition temperature (DBTT) and the upper shelf energy (USE) of full size Charpy specimens based on subsize specimen data. The new DBTT and the USE correlations were tested against published experimental data on other ferritic steels and shown to perform successfully at lower USE particularly when both precracked and notched only specimens were employed

  11. Impact damage response of natural stitched single lap-joint in composite structures

    International Nuclear Information System (INIS)

    Ghasemnejad, H.; Argentiero, Y.; Tez, T.A.; Barrington, P.E.

    2013-01-01

    Highlights: • To study the impact resistance of single lap-joints in composite structures. • To improve the impact resistance of stitched single lap joints using natural Flax yarn. • To investigate the effect of stitching on the damage process of composite materials. • To develop FE techniques to model the impact process of composite structures using LSDYNA. - Abstract: In this paper the damage behaviour of natural stitched composite single lap-joints are investigated under low velocity impact loading conditions. For this study, the laminated hybrid composite beams were pinned using Flax yarns before curing process. The Charpy impact test was chosen to study the energy absorbing capability of single lap composite joints. Composite beams were fabricated from combination of glass/epoxy and carbon/epoxy composites. It was shown that composite beams which are stitched through the thickness are able to absorb more energy in comparison with adhesive bonded composite joints in the hybrid composite beams. The Charpy impact test of stitched composite single lap joint was also simulated by finite element analysis using software LS-DYNA and the results verified with relevant experimental data

  12. Constitutively active Notch1 converts cranial neural crest-derived frontonasal mesenchyme to perivascular cells in vivo

    Directory of Open Access Journals (Sweden)

    Sophie R. Miller

    2017-03-01

    Full Text Available Perivascular/mural cells originate from either the mesoderm or the cranial neural crest. Regardless of their origin, Notch signalling is necessary for their formation. Furthermore, in both chicken and mouse, constitutive Notch1 activation (via expression of the Notch1 intracellular domain is sufficient in vivo to convert trunk mesoderm-derived somite cells to perivascular cells, at the expense of skeletal muscle. In experiments originally designed to investigate the effect of premature Notch1 activation on the development of neural crest-derived olfactory ensheathing glial cells (OECs, we used in ovo electroporation to insert a tetracycline-inducible NotchΔE construct (encoding a constitutively active mutant of mouse Notch1 into the genome of chicken cranial neural crest cell precursors, and activated NotchΔE expression by doxycycline injection at embryonic day 4. NotchΔE-targeted cells formed perivascular cells within the frontonasal mesenchyme, and expressed a perivascular marker on the olfactory nerve. Hence, constitutively activating Notch1 is sufficient in vivo to drive not only somite cells, but also neural crest-derived frontonasal mesenchyme and perhaps developing OECs, to a perivascular cell fate. These results also highlight the plasticity of neural crest-derived mesenchyme and glia.

  13. ERK inhibition enhances TSA-induced gastric cancer cell apoptosis via NF-κB-dependent and Notch-independent mechanism.

    Science.gov (United States)

    Yao, Jun; Qian, Cui-Juan; Ye, Bei; Zhang, Xin; Liang, Yong

    2012-09-04

    To analyze the combined impact of the histone deacetylase inhibitor (HDACI) Trichostatin A (TSA) and the extracellular-signal-regulated kinase 1/2 (ERK1/2) inhibitor PD98059 on gastric cancer (GC) cell line SGC7901 growth. SGC7901 cells were treated with TSA, PD98059 or with a TSA-PD98059 combination. Effects of drug treatment on tumor cell proliferation, apoptosis, cell cycle progression, and cell signaling pathways were investigated by MTS assay, flow cytometry, Western blotting, chromatin immunoprecipitation (ChIP) assay, electrophoretic mobility shift assay (EMSA), and luciferase reporter assay, respectively. PD98059 enhanced TSA-induced cell growth arrest, apoptosis and activation of p21(WAF1/CIP1), but reversed TSA-induced activation of ERK1/2 and nuclear factor-κB (NF-κB). TSA alone up-regulated Notch1 and Hes1, and down-regulated Notch2, but PD98059 did not affect the trends of Notch1 and Notch2 induced by TSA. Particularly, PD98059 did potentiate the ability of TSA to down-regulate phospho-histone H3 protein, but increased levels of the acetylated forms of histone H3 bound to the p21(WAF1/CIP1) promoter, leading to enhanced expression of p21(WAF1/CIP1) in SGC7901 cells. PD98059 synergistically potentiates TSA-induced GC growth arrest and apoptosis by manipulating NF-κB and p21(WAF1/CIP1) independent of Notch. Therefore, concomitant administration of HDACIs and ERK1/2 inhibitors may be a promising treatment strategy for individuals with GC. Copyright © 2012 Elsevier Inc. All rights reserved.

  14. Fibre Optic Notch Filter For The Antiproton Decelerator Stochastic Cooling System

    CERN Document Server

    Simmonds, Max Vincent John

    2016-01-01

    The project scope included reverse engineering, upgrading, and recovering the operational conditions of an existing fibre optic notch filter. Once operational, tests were to be preformed to confirm the performance of the temperature stabilisation. The end goal is to use said notch filter in the Antiproton Decelerator (AD) facility at CERN to help aid antimatter research. The notch filter was successfully reverse engineered and then documented. Changes were made in order to increase performance and reliability, and also allow easy integration into the AD. An additional phase was added whereby the notch filter was to be controller via a touchscreen computer, situated next to the filter, allowing engineers to set-up each of the electronic devices used. While one of the devices (Motorised Delay Line) can be controlled by the touchscreen computer, the other two cannot.Due to time constraints and difficulties with the Beckhoff TwincatII programming language, the USB devices were not able to be controlled via the To...

  15. Applicability of the fracture toughness master curve to irradiated reactor pressure vessel steels

    International Nuclear Information System (INIS)

    Sokolov, M.A.; McCabe, D.E.; Alexander, D.J.; Nanstad, R.K.

    1997-01-01

    The current methodology for determination of fracture toughness of irradiated reactor pressure vessel (RPV) steels is based on the upward temperature shift of the American Society of Mechanical Engineers (ASME) K Ic curve from either measurement of Charpy impact surveillance specimens or predictive calculations based on a database of Charpy impact tests from RPV surveillance programs. Currently, the provisions for determination of the upward temperature shift of the curve due to irradiation are based on the Charpy V-notch (CVN) 41-J shift, and the shape of the fracture toughness curve is assumed to not change as a consequence or irradiation. The ASME curve is a function of test temperature (T) normalized to a reference nit-ductility temperature, RT NDT , namely, T-RT NDT . That curve was constructed as the lower boundary to the available K Ic database and, therefore, does not consider probability matters. Moreover, to achieve valid fracture toughness data in the temperature range where the rate of fracture toughness increase with temperature is rapidly increasing, very large test specimens were needed to maintain plain-strain, linear-elastic conditions. Such large specimens are impractical for fracture toughness testing of each RPV steel, but the evolution of elastic-plastic fracture mechanics has led to the use of relatively small test specimens to achieve acceptable cleavage fracture toughness measurements, K Jc , in the transition temperature range. Accompanying this evolution is the employment of the Weibull distribution function to model the scatter of fracture toughness values in the transition range. Thus, a probabilistic-based bound for a given data population can be made. Further, it has been demonstrated by Wallin that the probabilistic-based estimates of median fracture toughness of ferritic steels tend to form transition curves of the same shape, the so-called ''master curve'', normalized to one common specimen size, namely the 1T [i.e., 1.0-in

  16. Notch signaling in embryology and cancer

    National Research Council Canada - National Science Library

    Reichrath, J; Reichrath, Sandra

    2012-01-01

    "The goal of this volume is to comprehensively cover a highly readable overview on our present knowledge of the role of Notch signalling for embryology and cancer, with a focus on new findings in molecular biology...

  17. On the notch ductility of a magnesium-rare earth alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kondori, B., E-mail: bkondori.13034@tamu.edu [Department of Materials Science & Engineering, Texas A& M University, College Station, TX 77843 (United States); Benzerga, A.A. [Department of Materials Science & Engineering, Texas A& M University, College Station, TX 77843 (United States); Department of Aerospace Engineering, Texas A& M University, College Station, TX 77843 (United States)

    2015-10-28

    The room-temperature notch ductility of magnesium-rare earth alloy WE43 is investigated for two loading orientations. This material is endowed with quasi-isotropic plastic flow properties, higher strength and similar uniaxial ductility in comparison with other commercially available Mg alloys. The authors have recently shown that the notch ductility of a Mg–Al–Zn alloy is greater than its uniaxial ductility over a wide range of notch geometries. This paper investigates whether the same trends hold for WE43, discusses the orientation dependence of ductility and the propensity for intergranular fracture at high levels of hydrostatic tension. The latter mode of fracture is analyzed by means of detailed fractography in order to elucidate the role of grain-boundary particles and precipitates in the fracture process.

  18. The effect of electric discharge machined notches on the fracture toughness of several structural alloys

    International Nuclear Information System (INIS)

    Joyce, J.A.; Link, R.E.

    1993-09-01

    Recent computational studies of the stress and strain fields at the tip of very sharp notches have shown that the stress and strain fields are very weakly dependent on the initial geometry of the notch once the notch has been blunted to a radius that is 6 to 10 times the initial root radius. It follows that if the fracture toughness of a material is sufficiently high so that fracture initiation does not occur in a specimen until the crack-tip opening displacement (CTOD) reaches a value from 6 to 10 times the size of the initial notch tip diameter, then the fracture toughness will be independent of whether a fatigue crack or a machined notch served as the initial crack. In this experimental program the fracture toughness (J Ic and J resistance (J-R) curve, and CTOD) for several structure alloys was measured using specimens with conventional fatigue cracks and with EDM machined notches. The results of this program have shown, in fact, that most structural materials do not achieve initiation CTOD values on the order of 6 to 10 times the radius of even the smallest EDM notch tip presently achievable. It is found furthermore that tougher materials do not seem to be less dependent on the type of notch tip present. Some materials are shown to be much more dependent on the type of notch tip used, but no simple pattern is found that relates this observed dependence to the material strength toughness, or strain hardening rate

  19. Deubiquitinase inhibitor b-AP15 activates endoplasmic reticulum (ER) stress and inhibits Wnt/Notch1 signaling pathway leading to the reduction of cell survival in hepatocellular carcinoma cells.

    Science.gov (United States)

    Ding, Youming; Chen, Xiaoyan; Wang, Bin; Yu, Bin; Ge, Jianhui

    2018-04-15

    b-AP15, a potent and selective inhibitor of the ubiquitin-specific peptidase 14 (USP14), displays in vitro and in vivo antitumor abilities on some types of cancer cells. However, the mechanism underlying its action is not well elucidated. The purposes of the present study are to observe the potential impacts of b-AP15 on cell survival of hepatocellular carcinoma cells and to investigate whether and how this compound inhibits some survival-promoting signaling pathways. We found that b-AP15 significantly decreased cell viability and increased cell apoptosis in a dose-dependent manner in hepatocellular carcinoma cells, along with the perturbation of cell cycle and the decreased expressions of cell cycle-related proteins. We also demonstrated that the endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) were enhanced by b-AP15 supplementation. The inhibition of ER stress/UPR only partly attenuated the cytotoxicity of b-AP15 on hepatocellular carcinoma cells. In addition, b-AP15 treatment inhibited Wnt/β-catenin and Notch1 signaling pathways, and suppressed phosphorylation of STAT3, Akt, and Erk1/2, which were not restored by the inhibition of ER stress/UPR. Furthermore, the expression levels of signaling molecules in Notch1 were reduced by specific inhibitor of Wnt/β-catenin pathway. Notably, either Wnt or Notch1 signaling inhibitor mitigated phosphorylation of STAT3, Akt, and Erk1/2, and mimicked the cytotoxicity of b-AP15 on hepatocellular carcinoma cells. These results clearly indicate that b-AP15 induced cytotoxic response to hepatocellular carcinoma cells by augmenting ER stress/UPR and inhibiting Wnt/Notch1 signaling pathways. This new finding provides a novel mechanism by which b-AP15 produces its antitumor therapeutic effects. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Experimental and Numerical Analysis of Notched Composites Under Tension Loading

    Science.gov (United States)

    Aidi, Bilel; Case, Scott W.

    2015-12-01

    Experimental quasi-static tests were performed on center notched carbon fiber reinforced polymer (CFRP) composites having different stacking sequences made of G40-600/5245C prepreg. The three-dimensional Digital Image Correlation (DIC) technique was used during quasi-static tests conducted on quasi-isotropic notched samples to obtain the distribution of strains as a function of applied stress. A finite element model was built within Abaqus to predict the notched strength and the strain profiles for comparison with measured results. A user-material subroutine using the multi-continuum theory (MCT) as a failure initiation criterion and an energy-based damage evolution law as implemented by Autodesk Simulation Composite Analysis (ASCA) was used to conduct a quantitative comparison of strain components predicted by the analysis and obtained in the experiments. Good agreement between experimental data and numerical analyses results are observed. Modal analysis was carried out to investigate the effect of static damage on the dominant frequencies of the notched structure using the resulted degraded material elements. The first in-plane mode was found to be a good candidate for tracking the level of damage.

  1. Notch root strain measurement of WE43-T6 magnesium alloy using electronic speckle pattern interferometry

    International Nuclear Information System (INIS)

    Liew, H.L.; Ahmad, A.; Ramesh, S.; Purbolaksono, J.

    2013-01-01

    Highlights: • The use of ESPI for measuring total strains at the notch root of specimens. • Fine meshing in micron scale at the notch root regions. • The maximum elastic strain is shifted to be further away from the notch root tip. - Abstract: The notch root elasto-plastic strains of circumferentially grooved round specimen of cast magnesium WE43-T6 were experimentally measured using the electronic speckle pattern interferometry (ESPI) and numerically evaluated using the finite element analysis (FEA). The specimens have notch radii of 1.6 mm and 0.8 mm and an opening angle of 60°. The technique of ESPI showed its accuracy in measuring three-dimensional surface deformations on large negatively curved manifolds. The measured nominal stress for rupture is well beyond the ultimate strength, suggesting the existence of significant biaxial stress at the notch root region. The ESPI-based strains on the notch tips were shown to be in agreement with those evaluated by the FEA. The FEA also showed that the maximum elastic strain is shifted away from the notch root surface as the plastic strain is predominant

  2. The Advanced Glaucoma Intervention Study (AGIS): 10. Variability among academic glaucoma subspecialists in assessing optic disc notching.

    Science.gov (United States)

    Gaasterland, D E; Blackwell, B; Dally, L G; Caprioli, J; Katz, L J; Ederer, F

    2001-01-01

    An analysis of data from the Advanced Glaucoma Intervention Study (AGIS) has found eyes reported to have partial optic disc rim notching (not to the edge) at baseline to have less risk of subsequent visual field loss than eyes with no notching. Because this is counterintuitive and because classification of notching had not been defined in the AGIS protocol, we have assessed AGIS ophthalmologists interobserver and intraobserver agreement on notching. Fourteen glaucoma subspecialists classified notching in 26 pairs of stereoscopic disc photographs of eyes with mild to severe glaucomatous optic neuropathy. They classified images as showing either no notching, notching not to the edge, or notching to the edge. Several hours later, 10 of them classified the same images a second time. In an analysis of interobserver agreement, of 26 stereoscopic images, a plurality of ophthalmologists classified notching as absent in 9 (35%), as present but not to the edge in 7 (27%), and as present and not to the edge in 10 (38%). All 14 ophthalmologists (100%) agreed on the classification of 7 (27%) of the images, and 13 of the 14 ophthalmologists (93%) agreed on the classification of 4 additional images (15%). Of these 11 images with at least 93% agreement, notching was reported as absent in 3 (27%) and to the edge in 8 (73%). In the remaining 15 images, there was substantial disagreement about whether notching was present and, if so, whether it was to the edge. In an analysis of intraobserver agreement, none of the 10 ophthalmologists who completed the viewing a second time classified all eyes exactly the same as the first time, though 5 ophthalmologists made 4 or fewer reclassifications. Overall, 80% of the original classifications were reproduced on second reading. Of the initial classifications that were not reproduced, slightly more than half were first classified as having notching not to the edge. Without definitions or examples of optic disc rim notching, the glaucoma

  3. Notch signaling regulates platelet-derived growth factor receptor-β expression in vascular smooth muscle cells

    NARCIS (Netherlands)

    Jin, S.; Hansson, E.M.; Tikka, S.; Lanner, F.; Sahlgren, C.; Farnebo, F.; Baumann, M.; Kalimo, H.; Lendahl, U.

    2008-01-01

    Notch signaling is critically important for proper architecture of the vascular system, and mutations in NOTCH3 are associated with CADASIL, a stroke and dementia syndrome with vascular smooth muscle cell (VSMC) dysfunction. In this report, we link Notch signaling to platelet-derived growth factor

  4. Minocycline attenuates the development of diabetic neuropathy by inhibiting spinal cord Notch signaling in rat.

    Science.gov (United States)

    Yang, Cheng; Gao, Jie; Wu, Banglin; Yan, Nuo; Li, Hui; Ren, Yiqing; Kan, Yufei; Liang, Jiamin; Jiao, Yang; Yu, Yonghao

    2017-10-01

    We studied the effects of minocycline (an inhibitor of microglial activation) on the expression and activity of Notch-1 receptor, and explored the therapeutic efficacy of minocycline combined with Notch inhibitor DAPT in the treatment of diabetic neuropathic pain (DNP). Diabetic rat model was established by intraperitoneal injection (ip) of Streptozotocin (STZ). Expression and activity of Notch-1 and expression of macrophage/microglia marker Iba-1 were detected by WB. Diabetes induction significantly attenuated sciatic nerve conduction velocity, and dramatically augmented the expression and the activity of Notch-1 in the lumbar enlargement of the spinal cord. Minocycline treatment, however, accelerated the decreased conduction velocity of sciatic nerve and suppressed Notch-1expression and activity in diabetic rats. Similar to DAPT treatment, minocycline administration also prolonged thermal withdrawal latency (TWL) and increase mechanical withdrawal threshold (MWT) in diabetic rats in response to heat or mechanical stimulation via inhibition the expression and the activity of Notch-1 in spinal cord. Combination of DAPT and minocycline further inhibited Notch-1 receptor signaling and reduce neuropathic pain exhibited as improved TWL and MWT. Our study revealed a novel mechanism of Notch-1 receptor inhibition in spinal cord induced by minocycline administration, and suggested that the combination of minocycline and DAPT has the potential to treat DNP. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  5. Notch signaling mediates the age-associated decrease in adhesion of germline stem cells to the niche.

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    Chen-Yuan Tseng

    2014-12-01

    Full Text Available Stem cells have an innate ability to occupy their stem cell niche, which in turn, is optimized to house stem cells. Organ aging is associated with reduced stem cell occupancy in the niche, but the mechanisms involved are poorly understood. Here, we report that Notch signaling is increased with age in Drosophila female germline stem cells (GSCs, and this results in their removal from the niche. Clonal analysis revealed that GSCs with low levels of Notch signaling exhibit increased adhesiveness to the niche, thereby out-competing their neighbors with higher levels of Notch; adhesiveness is altered through regulation of E-cadherin expression. Experimental enhancement of Notch signaling in GSCs hastens their age-dependent loss from the niche, and such loss is at least partially mediated by Sex lethal. However, disruption of Notch signaling in GSCs does not delay GSC loss during aging, and nor does it affect BMP signaling, which promotes self-renewal of GSCs. Finally, we show that in contrast to GSCs, Notch activation in the niche (which maintains niche integrity, and thus mediates GSC retention is reduced with age, indicating that Notch signaling regulates GSC niche occupancy both intrinsically and extrinsically. Our findings expose a novel role of Notch signaling in controlling GSC-niche adhesion in response to aging, and are also of relevance to metastatic cancer cells, in which Notch signaling suppresses cell adhesion.

  6. Role of CSL-dependent and independent Notch signaling pathways in cell apoptosis.

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    Zeng, Chong; Xing, Rui; Liu, Jing; Xing, Feiyue

    2016-01-01

    Apoptosis is a normally biological phenomenon in various organisms, involving complexly molecular mechanisms with a series of signaling processes. Notch signaling is found evolutionarily conserved in many species, playing a critical role in embryonic development, normal tissue homeostasis, angiogenesis and immunoregulation. The focus of this review is on currently novel advances about roles of CSL-dependent and independent Notch signaling pathways in cell apoptosis. The CSL can bind Notch intracellular domain (NIC) to act as a switch in mediating transcriptional activation or inactivation of the Notch signaling pathway downstream genes in the nucleus. It shows that CSL-dependent signaling regulates the cell apoptosis through Hes-1-PTEN-AKT-mTOR signaling, but rather the CSL-independent signaling mediates the cell apoptosis possibly via NIC-mTORC2-AKT-mTOR signaling, providing a new insight into apoptotic mechanisms.

  7. Design of UWB Filter with WLAN Notch

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    Harish Kumar

    2012-01-01

    Full Text Available UWB technology- (operating in broad frequency range of 3.1–10.6 GHz based filter with WLAN notch has shown great achievement for high-speed wireless communications. To satisfy the UWB system requirements, a band pass filter with a broad pass band width, low insertion loss, and high stop-band suppression are needed. UWB filter with wireless local area network (WLAN notch at 5.6 GHz and 3 dB fractional bandwidth of 109.5% using a microstrip structure is presented. Initially a two-transmission-pole UWB band pass filter in the frequency range 3.1–10.6 GHz is achieved by designing a parallel-coupled microstrip line with defective ground plane structure using GML 1000 substrate with specifications: dielectric constant 3.2 and thickness 0.762 mm at centre frequency 6.85 GHz. In this structure a λ/4 open-circuited stub is introduced to achieve the notch at 5.6 GHz to avoid the interference with WLAN frequency which lies in the desired UWB band. The design structure was simulated on electromagnetic circuit simulation software and fabricated by microwave integrated circuit technique. The measured VNA results show the close agreement with simulated results.

  8. Glioma cell fate decisions mediated by Dll1-Jag1-Fringe in Notch1 signaling pathway.

    Science.gov (United States)

    Shi, Xiaofei