637 research outputs found

    Modeling of Late Blooming Phases and Precipitation Kinetics in Aging Reactor Pressure Vessel (RPV) Steels

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    The principle work at the atomic scale is to develop a predictive quantitative model for the microstructure evolution of RPV steels under thermal aging and neutron radiation. We have developed an AKMC method for the precipitation kinetics in bcc-Fe, with Cu, Ni, Mn and Si being the alloying elements. In addition, we used MD simulations to provide input parameters (if not available in literature). MMC simulations were also carried out to explore the possible segregation/precipitation morphologies at the lattice defects. First we briefly describe each of the simulation algorithms, then will present our results

    The SNR G106.3+2.7 and its Pulsar Wind Nebula: relics of triggered star formation in a complex environment

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    We propose that the pulsar nebula associated with the pulsar J2229+6114 and the supernova remnant (SNR) G106.3+2.7 are the result of the same supernova explosion. The whole structure is located at the edge of an HI bubble with extended regions of molecular gas inside. The radial velocities of both the atomic hydrogen and the molecular material suggest a distance of 800 pc. At this distance the SNR is 14 pc long and 6 pc wide. Apparently the bubble was created by the stellar wind and supernova explosions of a group of stars in its center which also triggered the formation of the progenitor star of G106.3+2.7. The progenitor star exploded at or close to the current position of the pulsar, which is at one end of the SNR rather than at its center. The expanding shock wave of the supernova explosion created a comet shaped supernova remnant by running into dense material and then breaking out into the inner part of the HI bubble. A synchrotron nebula with a shell-like structure (the ``Boomerang'') of length 0.8 pc was created by the pulsar wind interacting with the dense ambient medium. The expanding shock wave created an HI shell of mass 0.4 Msun around this nebula by ionizing the atomic hydrogen in its vicinity.Comment: 10 pages, Latex, with aastex and emulateapj5, 5 figures. ApJ, accepted, scheduled for the v560 n1 p1 Oct 10, 2001 issu

    Modeling the Ductile Brittle Fracture Transition in Reactor Pressure Vessel Steels Using a Cohesive Zone Model Based Approach

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    Fracture properties of Reactor Pressure Vessel (RPV) steels show large variations with changes in temperature and irradiation levels. Brittle behavior is observed at lower temperatures and/or higher irradiation levels whereas ductile mode of failure is predominant at higher temperatures and/or lower irradiation levels. In addition to such temperature and radiation dependent fracture behavior, significant scatter in fracture toughness has also been observed. As a consequence of such variability in fracture behavior, accurate estimates of fracture properties of RPV steels are of utmost importance for safe and reliable operation of reactor pressure vessels. A cohesive zone based approach is being pursued in the present study where an attempt is made to obtain a unified law capturing both stable crack growth (ductile fracture) and unstable failure (cleavage fracture). The parameters of the constitutive model are dependent on both temperature and failure probability. The effect of irradiation has not been considered in the present study. The use of such a cohesive zone based approach would allow the modeling of explicit crack growth at both stable and unstable regimes of fracture. Also it would provide the possibility to incorporate more physical lower length scale models to predict DBT. Such a multi-scale approach would significantly improve the predictive capabilities of the model, which is still largely empirical

    Real-world efficacy and safety of Ledipasvir + Sofosbuvir and Ombitasvir/Paritaprevir/Ritonavir ± Dasabuvir combination therapies for chronic hepatitis C: A Turkish experience

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    Background/Aims: This study aimed to evaluate the real-life efficacy and tolerability of direct-acting antiviral treatments for patients with chronic hepatitis C (CHC) with/without cirrhosis in the Turkish population. Material and Methods: A total of 4,352 patients with CHC from 36 different institutions in Turkey were enrolled. They received ledipasvir (LDV) and sofosbuvir (SOF)+/- ribavirin (RBV) ombitasvir/paritaprevir/ritonavir +/- dasabuvir (PrOD)+/- RBV for 12 or 24 weeks. Sustained virologic response (SVR) rates, factors affecting SVR, safety profile, and hepatocellular cancer (HCC) occurrence were analyzed. Results: SVR12 was achieved in 92.8% of the patients (4,040/4,352) according to intention-to-treat and in 98.3% of the patients (4,040/4,108) according to per-protocol analysis. The SVR12 rates were similar between the treatment regimens (97.2%-100%) and genotypes (95.6%-100%). Patients achieving SVR showed a significant decrease in the mean serum alanine transaminase (ALT) levels (50.90 +/- 54.60 U/L to 17.00 +/- 14.50 U/L) and model for end-stage liver disease (MELD) scores (7.51 +/- 4.54 to 7.32 +/- 3.40) (p<0.05). Of the patients, 2 were diagnosed with HCC during the treatment and 14 were diagnosed with HCC 37.0 +/- 16.0 weeks post-treatment. Higher initial MELD score (odds ratio [OR]: 1.92, 95% confidence interval [CI]: 1.22-2.38; p=0.023]), higher hepatitis C virus (HCV) RNA levels (OR: 1.44, 95% CI: 1.31-2.28; p=0.038), and higher serum ALT levels (OR: 1.38, 95% CI: 1.21-1.83; p=0.042) were associated with poor SVR12. The most common adverse events were fatigue (12.6%), pruritis (7.3%), increased serum ALT (4.7%) and bilirubin (3.8%) levels, and anemia (3.1%). Conclusion: LDV/SOF or PrOD +/- RBV were effective and tolerable treatments for patients with CHC and with or without advanced liver disease before and after liver transplantation. Although HCV eradication improves the liver function, there is a risk of developing HCC.Turkish Association for the Study of The Liver (TASL)The present study was supported by The Turkish Association for the Study of The Liver (TASL)

    Subcutaneous hydatid cysts occurring in the palm and the thigh: two case reports

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    <p>Abstract</p> <p>Introduction</p> <p>Hydatid cyst disease is common in some regions of the world and is usually located in the liver and lungs. This report presents two cases of primary hydatid cysts located subcutaneously: one in the medial thigh and one in the left palm between the index and middle fingers.</p> <p>Case presentations</p> <p>A 64-year-old male farmer visited our hospital because a swelling on the right medial thigh had grown during the last year. Superficial ultrasound and computed tomography revealed a lesion resembling a hydatid cyst. A germinative membrane was encountered during surgical excision. Pathological examination was compatible with a hydatid cyst. The second case involved a 67-year-old male farmer who complained of a swelling that had grown in his left palm in the last year. The preliminary diagnosis was a lipoma. However, a hydatid cyst was diagnosed during surgical excision and after the pathological examination. The patient did not have a history of hydatid cyst disease and hydatid cysts were not detected in other organs. There has been no disease recurrence after following both patients for 3 years.</p> <p>Conclusion</p> <p>A hydatid cyst should be considered in the differential diagnosis of subcutaneous cystic lesions in regions where hydatid cysts are endemic, and should be excised totally, with an intact wall, to avoid recurrence.</p

    Single dose of secnidazole treatment against naturally occuring Giardia duodenalis infection in Sakiz lambs

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    ABSTRACT Objective. The purposes of this study were to determine whether secnidazole administered at a single dose of 10 mg/kg, orally, lessens or eliminates Giardia cyst shedding, and to validate the benefit of secnidazole treatment on clinical signs and faecal consistency in lambs naturally infected with Giardia duodenalis. Materials and methods. To this extent weaned 12 weeks of age lambs were selected and randomly assigned into two groups based on placebo (group C, n=7 untreated control group) or treatment (group S, n=10 lambs treated with a single dose of secnidazole at 10 mg/kg). Results. On days 0 and 10, before and after treatment, respectively, reduction in cyst excretion was determined. The faecal consistency and general health were recorded at each sampling day. Conclusions. During the study there was a high (99.98%) reduction in cyst excretion in the secnidazol treatment group compared to the positive control group on day 10, resulting in a significant (p<0.001) reduction, making secnidazole highly effective treatment option
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