The electron-capture origin of supernova 2018zd

In the transitional mass range ($\sim$ 8-10 solar masses) between white dwarf formation and iron core-collapse supernovae, stars are expected to produce an electron-capture supernova. Theoretically, these progenitors are thought to be super-asymptotic giant branch stars with a degenerate O+Ne+Mg core, and electron capture onto Ne and Mg nuclei should initiate core collapse. However, no supernovae have unequivocally been identified from an electron-capture origin, partly because of uncertainty in theoretical predictions. Here we present six indicators of electron-capture supernovae and show that supernova 2018zd is the only known supernova having strong evidence for or consistent with all six: progenitor identification, circumstellar material, chemical composition, explosion energy, light curve, and nucleosynthesis. For supernova 2018zd, we infer a super-asymptotic giant branch progenitor based on the faint candidate in the pre-explosion images and the chemically-enriched circumstellar material revealed by the early ultraviolet colours and flash spectroscopy. The light-curve morphology and nebular emission lines can be explained with the low explosion energy and neutron-rich nucleosynthesis produced in an electron-capture supernova. This identification provides insights into the complex stellar evolution, supernova physics, cosmic nucleosynthesis, and remnant populations in the transitional mass range.Comment: Author version of the published letter in Nature Astronomy, 28 June 202

The electron-capture origin of supernova 2018zd

In the transitional mass range (~8–10 solar masses) between white dwarf formation and iron core-collapse supernovae, stars are expected to produce an electron-capture supernova. Theoretically, these progenitors are thought to be super-asymptotic giant branch stars with a degenerate O + Ne + Mg core, and electron capture onto Ne and Mg nuclei should initiate core collapse1–4. However, no supernovae have unequivocally been identified from an electron-capture origin, partly because of uncertainty in theoretical predictions. Here we present six indicators of electron-capture supernovae and show that supernova 2018zd is the only known supernova with strong evidence for or consistent with all six: progenitor identification, circumstellar material, chemical composition5–7, explosion energy, light curve and nucleosynthesis8–12. For supernova 2018zd, we infer a super-asymptotic giant branch progenitor based on the faint candidate in the pre-explosion images and the chemically enriched circumstellar material revealed by the early ultraviolet colours and flash spectroscopy. The light-curve morphology and nebular emission lines can be explained by the low explosion energy and neutron-rich nucleosynthesis produced in an electron-capture supernova. This identification provides insights into the complex stellar evolution, supernova physics, cosmic nucleosynthesis and remnant populations in the transitional mass range. Electron-capture supernovae are thought to come from progenitors with a narrow range of masses, and thus they are rare. Here the authors present six indicators of an electron-capture supernova origin, and find that supernova 2018zd fulfils all six criteria.Instituto de Astrofísica de La PlataFacultad de Ciencias Astronómicas y Geofísica

フソバクテリウム ヌクレアタムはNOD1/RIPK2/NF-κB経路を介して食道扁平上皮癌の進展に寄与する

熊本大

Laparoscopic removal of an ingested fish bone that penetrated the stomach and was embedded in the pancreas: a case report

Abstract Background The gastrointestinal tract can occasionally be perforated or penetrated by an ingested foreign body, such as a fish bone. However, there are very few reported cases in which an ingested fish bone penetrated the gastrointestinal tract and was embedded in the pancreas. Case presentation An 80-year-old male presented with epigastric pain. Computed tomography of the abdomen showed a linear, hyperdense, foreign body that penetrated through the posterior wall of the gastric antrum. There was no evidence of free air, abscess formation, migration of the foreign body into the pancreas, or pancreatitis. As the patient had a history of fish bone ingestion, we made a diagnosis of localized peritonitis caused by fish bone penetration of the posterior wall of the gastric antrum. We first attempted to remove the foreign body endoscopically, but failed because it was not detected. Hence, an emergency laparoscopic surgery was performed. A linear, hard, foreign body penetrated through the posterior wall of the gastric antrum and was embedded in the pancreas. The foreign body was safely removed laparoscopically and was identified as a 2.5-cm-long fish bone. Intraperitoneal lavage was performed, and a drain was placed in the lesser sac. The patient recovered without complications and was discharged on the 7th postoperative day. Conclusion Laparoscopic surgery could be performed safely for the removal of an ingested fish bone embedded in the pancreas

Palladium-Catalyzed Cyanothiolation of Internal Alkynes Using Organic Disulfides and <i>tert</i>-Butyl Isocyanide

Despite the availability of selective synthetic approaches to multifunctionalized substituted olefins, the cyanothiolation of internal alkynes has been much less explored. Herein, we show that nonactivated internal alkynes can be successfully cyanothiolated with diaryl disulfides and <i>tert</i>-butyl isocyanide in the presence of a Pd catalyst (e.g., Pd­(PPh₃)₄) with the release of isobutene and arenethiol to afford β-thiolated alkenyl cyanides in yields of 34–89%

Palladium-Catalyzed Cyanothiolation of Internal Alkynes Using Organic Disulfides and <i>tert</i>-Butyl Isocyanide

Despite the availability of selective synthetic approaches to multifunctionalized substituted olefins, the cyanothiolation of internal alkynes has been much less explored. Herein, we show that nonactivated internal alkynes can be successfully cyanothiolated with diaryl disulfides and <i>tert</i>-butyl isocyanide in the presence of a Pd catalyst (e.g., Pd­(PPh₃)₄) with the release of isobutene and arenethiol to afford β-thiolated alkenyl cyanides in yields of 34–89%

Palladium-Catalyzed Cyanothiolation of Internal Alkynes Using Organic Disulfides and <i>tert</i>-Butyl Isocyanide

Despite the availability of selective synthetic approaches to multifunctionalized substituted olefins, the cyanothiolation of internal alkynes has been much less explored. Herein, we show that nonactivated internal alkynes can be successfully cyanothiolated with diaryl disulfides and <i>tert</i>-butyl isocyanide in the presence of a Pd catalyst (e.g., Pd­(PPh₃)₄) with the release of isobutene and arenethiol to afford β-thiolated alkenyl cyanides in yields of 34–89%