On The Strength of Tribo-Emission in Sliding of Diamond on Single Crystal Silicon

Triboemission is a phenomenon associated with the sliding of variety of materials. The phenomenon is thought to be related to wear of diamond tools used in precision machining of semiconductors. As such, the physics of emission has recently acquired importance. Many researchers studied emission during scratching of solid surfaces. They observed that the intensity of tribo-induced emission of the electrons, ions, and photons decrease in the order: insulator>semiconductor> conductor. Many experiments conducted to compare the emission of negatively-charged particles in case of the semiconductors Si with that from selected insulators have reported a clear decreasing trend of the tribo-emission intensity as contact progressed over the same wear track for diamond-on-Si. Despite that all of these experiments were performed in vacuum, the origin of the weak signals and the decrease of signal strength in the case of Si centred on the presence of dielectric silicon oxide films formed in air during surface preparation or because of the samples being of mono-crystalline nature. This paper offers an alternative explanation to the behaviour of tribo-emitted particles based on the pressure induced semi-conductor-to-metallic phase transformation that takes place in Si during sliding. It is shown that due to repeated sliding, the wear tracks experience a semiconductor-to- metal transformation that renders the bulk of material immediately under the diamond slider conducting

Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10 years; 78.2% included were male with a median age of 37 years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020