Quantum-mechanical analysis of effect of alloying elements on ε-martensite start temperature of steels

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Nanomechanical characterization of quantum interference in a topological insulator nanowire

The discovery of two-dimensional gapless Dirac fermions in graphene and topological insulators (TI) has sparked extensive ongoing research toward applications of their unique electronic properties. The gapless surface states in three-dimensional insulators indicate a distinct topological phase of matter with a non-trivial Z2 invariant that can be verified by angle-resolved photoemission spectroscopy or magnetoresistance quantum oscillation. In TI nanowires, the gapless surface states exhibit Aharonov-Bohm (AB) oscillations in conductance, with this quantum interference effect accompanying a change in the number of transverse one-dimensional modes in transport. Thus, while the density of states (DOS) of such nanowires is expected to show such AB oscillation, this effect has yet to be observed. Here, we adopt nanomechanical measurements that reveal AB oscillations in the DOS of a topological insulator. The TI nanowire under study is an electromechanical resonator embedded in an electrical circuit, and quantum capacitance effects from DOS oscillation modulate the circuit capacitance thereby altering the spring constant to generate mechanical resonant frequency shifts. Detection of the quantum capacitance effects from surface-state DOS is facilitated by the small effective capacitances and high quality factors of nanomechanical resonators, and as such the present technique could be extended to study diverse quantum materials at nanoscale.Comment: 15+16 pages, 4+11 figure

Cosmesis and feasibility of transvaginal natural orifice Specimen extraction (NOSE) for large organ specimen: a prospective pilot study

This study aimed to evaluate cosmetic outcomes and feasibility of transvaginal natural orifice specimen extraction (NOSE) in patients who underwent laparoscopic or robotic surgery for the treatment of benign or malignant diseases of the kidney, liver, stomach, adrenal gland, and bladder. Methods This prospective study was conducted at a tertiary hospital between March 2015 and May 2020. The main outcome was cosmetic outcomes of scars assessed using the Patient and Observer Scar Assessment Scale (POSAS) 1 and 8 weeks after surgery. The secondary outcomes were postoperative pain, operating time, and complications. Sexual function was assessed using the Female Sexual Function Index (FSFI) questionnaire 6 months after surgery in 17 patients who were sexually active at the time of surgery. Results A total of 38 transvaginal NOSE procedures were performed for the extraction of 33 kidneys, 2 livers, 1 stomach, 1 adrenal gland, and 1 bladder. Observers rated pigmentation and relief scores as most deviant from normal skin (2.9 ± 1.7, 3.0 ± 2.1 at postoperative 1 week; 3.6 ± 1.9, 3.5 ± 2.2 at postoperative 8 weeks, respectively), but the overall scores of each item were low. The patients overall satisfaction with postoperative scars was high, and the mean scores for pain and itching were low, with significant improvement from the first week to the eighth week (P = 0.014 and P = 0.006, respectively). Patients also reported low scores on vaginal assessment items, indicating better symptoms, and bleeding improved significantly between the two time points (P = 0.001). Postoperative pain was reduced from moderate during the first 24h after surgery to mild after 24h. The mean operative time of the transvaginal NOSE procedure was 28.3 ± 13.3min. No postoperative complications were associated with the procedure. The mean FSFI total score was 21.2 ± 8.7 (cutoff score for dysfunction is 21), with higher scores indicating better sexual functioning. Conclusion Transvaginal NOSE seems to be a feasible procedure with promising cosmetic benefits, for patients who undergo minimally invasive surgery for large organs including the kidney, liver, stomach, adrenal gland, and bladder. A prospective randomized clinical trial is needed to provide solid evidence to support transvaginal NOSE. Trial registration: This trial is registered at ClinicalTrials.gov (NCT05113134).This study was supported by a grant (no. 02-2014-0055) from the Seoul National University Bundang Hospital Research Fund. The funding source played no role in the study design, collection, analysis, or interpretation of the data, writing of the report, or decision to submit the article

Influence of Carbon Content and Isothermal Heat Treatment Temperature on the Microstructure and Mechanical Properties of Ultra-High Strength Bainitic Steels

The effect of carbon content and isothermal heat treatment conditions on the microstructure evolution and mechanical properties of ultra-high strength bainitic steels was investigated. A reduction in carbon content from 0.8 wt% to 0.6 wt% in super-bainite steel with typical chemistry effectively improved not only the Charpy impact toughness but also the strength level. This suggests that reducing the carbon content is a very promising way to obtain better mechanical balance between strength and impact toughness. The higher Charpy impact toughness at a lower carbon content of 0.6 wt% is thought to result from a reduction in austenite fraction, and refinement of the austenite grain. The coarse austenite grains have a detrimental effect on impact toughness, by prematurely transforming to deformation-induced martensite during crack propagation. Mechanical properties were also affected by the isothermal treatment temperature. The lower isothermal temperature enhanced the formation of bainitic ferrite with a refined microstructure, which has a beneficial influence on strength, but reduces impact toughness. The lower impact toughness at lower isothermal temperature is attributed to the sluggish redistribution of carbon from the bainitic ferrite into the surrounding austenite. Higher solute carbon in the bainitic ferrite contributes to an increase of strength, but at the same time, encourages a propensity to cleavage fracture.11Ysciescopuskc

Clinical characteristics of 2009 pandemic influenza A (H1N1) infection in children and the performance of rapid antigen test

PurposeIn autumn 2009, the swine-origin influenza A (H1N1) virus spread throughout South Korea. The aims of this study were to determine the clinical characteristics of children infected by the 2009 H1N1 influenza A virus, and to compare the rapid antigen and real-time polymerase chain reaction (PCR) tests.MethodsWe conducted a retrospective review of patients ≥18 years of age who presented to Soonchunhyang University Hospital in Seoul with respiratory symptoms, including fever, between September 2009 and January 2010. A real-time PCR test was used to definitively diagnose 2009 H1N1 influenza A infection. Medical records of confirmed cases were reviewed for sex, age, and the time of infection. The decision to perform rapid antigen testing was not influenced by clinical conditions, but by individual factors such as economic conditions. Its sensitivity and specificity were evaluated compared to real-time PCR test results.ResultsIn total, 934 patients tested positive for H1N1 by real-time PCR. The highest number of patients (48.9%) was diagnosed in November. Most patients (48.2%) were aged between 6 and 10 years. Compared with the H1N1 real-time PCR test results, the rapid antigen test showed 22% sensitivity and 83% specificity. Seventy-eight patients were hospitalized for H1N1 influenza A virus infection, and fever was the most common symptom (97.4%).ConclusionFor diagnosis of 2009 H1N1 influenza A virus infection, the rapid antigen test was inferior to the real-time PCR test in both sensitivity and specificity. This outcome suggests that the rapid antigen test is inappropriate for screening

Regional Climate Model Intercomparison Project for Asia

Improving the simulation of regional climate change is one of the high-priority areas of climate study because regional information is needed for climate change impact assessments. Such information is especially important for the region covered by the East Asian monsoon where there is high variability in both space and time. To this end, the Regional Climate Model Intercomparison Project (RMIP) for Asia has been established to evaluate and improve regional climate model (RCM) simulations of the monsoon climate. RMIP operates under joint support of the Asia–Pacific Network for Global Change Research (APN), the Global Change System for Analysis, Research and Training (START), the Chinese Academy of Sciences, and several projects of participating nations. The project currently involves 10 research groups from Australia, China, Japan, South Korea, and the United States, as well as scientists from India, Italy, Mongolia, North Korea, and Russia. RMIP has three simulation phases: March 1997–August 1998, which covers a full annual cycle and extremes in monsoon behavior; January 1989–December 1998, which examines simulated climatology; and a regional climate change scenario, involving nesting with a global model. This paper is a brief report of RMIP goals, implementation design, and some initial results from the first phase studies