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Abstract: The effect of neutron irradiation on the mechanical properties of select molybdenum materials, unalloyed low carbon arc-cast (LCAC) Mo, Mo–0.5% Ti–0.1% Zr (TZM) alloy, and oxide dispersion-strengthened (ODS) Mo alloy, was characterized by analyzing the temperature dependence of mechanical properties. This study assembles the tensile test data obtained through multiple irradiation and post-irradiation experiments, in which tensile specimens were irradiated up to 13.1dpa at 80–1000°C and tested at −194 to 1000°C. Irradiation at 80–609°C increased yield stress significantly, up to 170%, while the increase of yield stress after irradiation at 784–936°C was not significant. The plastic instability stress was strongly dependent on test temperature but was nearly independent of irradiation dose and temperature. The true fracture stress showed weak dependences on test temperature, irradiation dose and temperature when ductile failure occurred. Among the test materials the stress-relieved ODS material in the longitudinal direction (ODS-LSR) displayed the highest resistance to irradiation embrittlement due to its relatively high fracture stress. The critical temperature for shear failure (CTSF) was defined and evaluated for the test materials and the CTSF values were compared with the ductile-to-brittle transition temperatures (DBTT) based on ductility data. [Copyright &y& Elsevier]

We present radio and optical afterglow observations of the TeV-bright long gamma-ray burst 190114C at a redshift of z = 0.425, which was detected by the Major Atmospheric Gamma Imaging Cherenkov telescope. Our observations with Atacama Large Millimeter/submillitmeter Array, Australia Telescope Compact Array , and upgraded Giant Metre-wave Radio Telescope were obtained by our low frequency observing campaign and range from ∼1 to ∼140 d after the burst and the optical observations were done with three optical telescopes spanning up to ∼25 d after the burst. Long-term radio/mm observations reveal the complex nature of the afterglow, which does not follow the spectral and temporal closure relations expected from the standard afterglow model. We find that the microphysical parameters of the external forward shock, representing the share of shock-created energy in the non-thermal electron population and magnetic field, are evolving with time. The inferred kinetic energy in the blast-wave depends strongly on the assumed ambient medium density profile, with a constant density medium demanding almost an order of magnitude higher energy than in the prompt emission, while a stellar wind-driven medium requires approximately the same amount energy as in prompt emission. [ABSTRACT FROM AUTHOR]

One of the major drawbacks of the Gurson-type of porous plasticity models is the inability of these models to predict material failure under low stress triaxiality, shear dominated conditions. This study addresses this issue by combining the damage mechanics concept with the porous plasticity model that accounts for void nucleation, growth and coalescence. In particular, the widely adopted Gurson-Tvergaard-Needleman (GTN) model is extended by coupling two damage parameters, representing the volumetric damage (void volume fraction) and the shear damage, respectively, into the yield function and flow potential. The effectiveness of the new model is illustrated through a series of numerical tests comparing its performance with existing models. The current model not only is capable of predicting damage and fracture under low (even negative) triaxiality conditions but also suppresses spurious damage that has been shown to develop in earlier modifications of the GTN model for moderate to high triaxiality regimes. Finally the modified GTN model is applied to predict the ductile fracture behavior of a beta-treated Zircaloy-4 by coupling the proposed damage modeling framework with a recently developed plasticity model for the matrix material. Model parameters are calibrated using experimental data, and the calibrated model predicts failure initiation and propagation in various specimens experiencing a wide range of triaxiality and Lode parameter combinations. [ABSTRACT FROM AUTHOR]

Highlights: [•] The strength differential effect between compression and tension for a beta-treated Zircaloy-4 is studied. [•] A pressure insensitive plasticity model depending on the second and third invariants of the stress deviator is developed. [•] The distortional hardening of the isotropic yield surface is modeled. [•] A series of experiments are conducted using specimens experiencing various stress states. [•] The calibrated model results in good agreement between numerical predictions and experimental measurements. [ABSTRACT FROM AUTHOR]

Background: Esomeprazole is the first proton pump inhibitor to be developed as an optical isomer for the treatment of acid-related diseases. Methods: Four hundred and forty eight duodenal ulcer patients with Helicobacter pylori infection, confirmed by 13C-urea breath test (UBT), and no current ulcer, were randomised to double-blind treatment with esomeprazole 20 mg twice daily (b.d.) (n=224) or omeprazole 20 mg b.d. (n=224), in combination with amoxicillin 1 g b.d. and clarithromycin 500 mg b.d. for 1 week (EAC and OAC, respectively). A negative UBT at both 4 and 8 weeks after completing therapy indicated successful H. pylori eradication. Results: Intention-to-treat (ITT) analysis comprised 400 patients (EAC, n=204; OAC, n=196) and per protocol (PP) analysis 377 patients (EAC, n=192; OAC, n=185). Eradication rates (95% confidence intervals) for ITT and PP populations were: EAC, 90% (85–94%) and 91% (86–94%); OAC, 88% (82–92%) and 91% (86–95%). Between-group differences in eradication rates were not statistically significant. Both regimens were well tolerated, with an adverse event profile and frequency typical of proton pump inhibitor plus antibiotic combination therapy. Conclusions: Esomeprazole-based triple therapy for 1 week is highly effective in eradicating H. pylori infection in duodenal ulcer disease, offers comparable efficacy to omeprazole-based therapy, and is well tolerated. [ABSTRACT FROM AUTHOR]

Long-duration γ-ray bursts (GRBs) originate from ultra-relativistic jets launched from the collapsing cores of dying massive stars. They are characterized by an initial phase of bright and highly variable radiation in the kiloelectronvolt-to-megaelectronvolt band, which is probably produced within the jet and lasts from milliseconds to minutes, known as the prompt emission 1,2 . Subsequently, the interaction of the jet with the surrounding medium generates shock waves that are responsible for the afterglow emission, which lasts from days to months and occurs over a broad energy range from the radio to the gigaelectronvolt bands 1-6 . The afterglow emission is generally well explained as synchrotron radiation emitted by electrons accelerated by the external shock 7-9 . Recently, intense long-lasting emission between 0.2 and 1 teraelectronvolts was observed from GRB 190114C 10,11 . Here we report multi-frequency observations of GRB 190114C, and study the evolution in time of the GRB emission across 17 orders of magnitude in energy, from 5 × 10 -6 to 10 12 electronvolts. We find that the broadband spectral energy distribution is double-peaked, with the teraelectronvolt emission constituting a distinct spectral component with power comparable to the synchrotron component. This component is associated with the afterglow and is satisfactorily explained by inverse Compton up-scattering of synchrotron photons by high-energy electrons. We find that the conditions required to account for the observed teraelectronvolt component are typical for GRBs, supporting the possibility that inverse Compton emission is commonly produced in GRBs.

Objective: To assess Helicobacter pylori eradication after one week dual ranitidine bismuth citrate-clarithromycin (RBC-C) or triple omeprazole, clarithromycin and amoxicillin (OCA) therapy., Methods: In this multicentre Canadian trial, H pylori-positive patients with functional dyspepsia or inactive peptic ulcer disease were randomized to open-label treatment with RBC-C (ranitidine bismuth citrate 400 mg plus clarithromycin 500 mg) or OCA (omezaprole 20 mg, clarithromycin 500 mg and amoxicillin 1000 mg), given twice a day for seven days. Treatment allocation was randomly assigned. H pylori infection was confirmed by positive 13C-urea breath test (13C-UBT). H pylori status was reassessed by UBT at least four and 12 weeks after treatment (negative: d13CO2 below 3.5 per mil). Intention-to-treat (ITT) eradication rates were determined for all patients with confirmed H pylori infection. Per protocol (PP) rate was determined for all patients treated with at least two evaluable follow-up visits., Results: Three hundred five patients were included in the ITT and 222 in the PP analysis. The ITT eradication rates were 66% for RBC-C and 78% for OCA. The PP success rates were 84% for RBC-C and 96% for OCA. The difference for both ITT 12% (95% CI 2 to 22) and PP 12% (95% CI 4 to 19) were statistically significant, P=0.030 and P=0.007, respectively. Treatment was generally well tolerated., Conclusion: The eradication rate for the seven-day dual RBC-C regimen was lower than that for OCA.

Despite a decreased incidence of ulcer disease and improvements in the management of acute upper gastrointestinal (GI) bleeding, mortality remains at about 6-7%. Although endoscopic haemostatic therapy has been demonstrated to be the mainstay of management, the search continues for less invasive medical modalities that might also improve patient outcome. In vitro data have indicated the important role of acid in impairing haemostasis and causing clot digestion. Therefore, theoretically, maintenance of a high intragastric pH (above 6.0) during management of upper GI bleeding is warranted. Until recently, available agents did not permit such a sustained elevation in gastric pH. Early studies with H2-receptor antagonists have not demonstrated significant improvements in important patient outcomes, such as rebleeding, surgery or mortality. With the availability of intravenous formulations of proton pump inhibitors, it is now possible to aim at maintaining gastric pH above 6.0 for 24 h per day. Recent clinical trial data would appear to support the use of proton pump inhibitors to decrease the rate of rebleeding and the need for surgery. This paper provides a review of non-variceal acute GI bleeding, with special reference to the role of proton pump inhibitors in this clinical setting.