2,914 research outputs found

    Disorder-dependent Li diffusion in Li6PS5Cl\mathrm{Li_6PS_5Cl} investigated by machine learning potential

    Full text link
    Solid-state electrolytes with argyrodite structures, such as Li6PS5Cl\mathrm{Li_6PS_5Cl}, have attracted considerable attention due to their superior safety compared to liquid electrolytes and higher ionic conductivity than other solid electrolytes. Although experimental efforts have been made to enhance conductivity by controlling the degree of disorder, the underlying diffusion mechanism is not yet fully understood. Moreover, existing theoretical analyses based on ab initio MD simulations have limitations in addressing various types of disorder at room temperature. In this study, we directly investigate Li-ion diffusion in Li6PS5Cl\mathrm{Li_6PS_5Cl} at 300 K using large-scale, long-term MD simulations empowered by machine learning potentials (MLPs). To ensure the convergence of conductivity values within an error range of 10%, we employ a 25 ns simulation using a 5×5×55\times5\times5 supercell containing 6500 atoms. The computed Li-ion conductivity, activation energies, and equilibrium site occupancies align well with experimental observations. Notably, Li-ion conductivity peaks when Cl ions occupy 25% of the 4c sites, rather than at 50% where the disorder is maximized. This phenomenon is explained by the interplay between inter-cage and intra-cage jumps. By elucidating the key factors affecting Li-ion diffusion in Li6PS5Cl\mathrm{Li_6PS_5Cl}, this work paves the way for optimizing ionic conductivity in the argyrodite family.Comment: 34 pages, 6 figure

    Clinical Characteristics of Radiation Oncology in Korea during Past 10 Years

    Get PDF
    To understand trends in the clinical characteristics of radiation oncology over the last 10 yr in Korea, annual survey questionnaires were sent to all of Korean radiation oncology facilities since 1990. Questionnaires addressed basic radiation therapy facilities and the clinical information. Responses were obtained from all facilities, and data collected from 1997 to 2006 was analyzed. The numbers of new patients that have undergone radiation therapy and the numbers of hospitals with a department of radiation oncology have steadily increased over the past 10 yr, and totaled 37,215 patients and 60 hospitals, respectively, in 2006. However, the proportion of patients irradiated among total cancer patients has remained below 30% over the last 10 yr. The numbers of prostate cancer, breast cancer, and hepatoma have increased by more than 3 fold over the past 10 yr. Moreover, the percentage of irradiated patients treated by brachytherapy was 10.3% in 1997, but this gradually fell to only 4.2% in 2006. The information collected described the role played by radiation oncology in Korea. Continuous surveys are required to enable trends to be detected

    Recognition of body image and food behavior factors among middle school students in San Francisco area

    Get PDF
    The purpose of this study was to determine the recognition of body image and food behavior factors according to the BMI. The subjects of this study were 242 7th grade students resided in San Francisco area. The degree of recognition for self-estimated physique of subjects by gender and by race showed no significant differences by gender but significant differences by race, showing that 20.0% was considered as underweight in Asian and 7.5% was considered as underweight in White students. This showed the same tendency as actual physique status (BMI). Also, the ratio of being recognized as more than overweight was 17.3% in Asian, 23.3% in Hispanic, and 13.4% in White students. In case of female students, the ratio of dieting experience was 63.3%, and 49.3% of White students and 63.3% of Hispanic students experienced dieting. In case of students answered not healthy, their body weight were significantly higher than those answered as healthy, and the BMI was also over 19, showing significant differences. Thus cases that answered as not healthy had greater body weight and BMI. Also it showed that frequent dieting experience is related to higher height and weight. The analysis of food behavior factors perceived by body shape showed that the group perceived itself as overweight consumed more 'fast food' but had low scores in 'vegetables' intake, with frequent intake of 'soda' and tendency to 'overeat'. Also, the tendency for 'balanced life' was significantly lower and for skipping breakfast was significantly higher, suggesting problematic food behavior

    Adenoviral Pneumonia During Etanercept Treatment in a Patient with Rheumatoid Arthritis

    Get PDF
    Inhibitors of tumor necrosis factor-alpha (TNF-α) have been approved for treating rheumatoid arthritis. As one of the biological response modifiers, etanercept has also been used in the treatment of psoriatic arthritis and inflammatory bowel disease. While etanercept is effective, certain infectious complications, such as tuberculosis, fungus, and cytomegalovirus, have been reported. We report the first Korean case of adenoviral pneumonia in a 55-year-old female who developed disseminated adenoviral infection following etanercept treatment, which resolved after anti-TNF-α discontinuation

    Vagus Nerve Stimulation in Intractable Childhood Epilepsy: a Korean Multicenter Experience

    Get PDF
    We evaluated the long-term outcome of vagus nerve stimulation (VNS) in 28 children with refractory epilepsy. Of these 28 children, 15 (53.6%) showed a >50% reduction in seizure frequency and 9 (32.1%) had a >75% reduction. When we compared seizure reduction rates according to seizure types (generalized vs. partial) and etiologies (symptomatic vs. cryptogenic), we found no significant differences. In addition, there was no correlation between the length of the stimulation period and treatment effect. The seizure reduction rate, however, tended to be inversely related to the seizure duration before VNS implantation and age at the time of VNS therapy. VNS also improved quality of life in this group of patients, including improved memory in 9 (32.1%), improved mood in 12 (42.9%), improved behavior in 11 (39.3%), improved altertness in 12 (42.9%), improved achievement in 6 (21.4%), and improved verbal skills in 8 (28.6%). Adverse events included hoarseness in 7 patients, dyspnea at sleep in 2 patients, and wound infection in 1 patient, but all were transient and successfully managed by careful follow-up and adjustment of parameters. These results indicate that VNS is a safe and effective alternative therapy for pediatric refractory epilepsy, without significant adverse events

    Anomalous Si-based composite anode design by densification and coating strategies for practical applications in Li-ion batteries

    Get PDF
    Si-based Li-ion battery (LIB) anode materials often possess porous structures to accommodate the intrinsic volumetric expansion of Si upon cycling. However, the porous structure may cause poor initial coulombic efficiency (ICE), inadequate cycle life due to the continuous generation of a solid-electrolyte interface, and incompatibility with calendaring processes. To overcome these issues, we designed an optimized Si/C (P?Si/C) composite anode consisting of Si nanoparticles, graphite, and pitch, with a highly densified structure, suppressing Si expansion and enabling compatibility with the calendaring process. To further enhance the cycle life, the surface of the P?Si/C composite was modified by chemical vapor deposition using CH4 gas (C?Si/C). The P?Si/C anode exhibited a high ICE of 88.0% with a rapid surge up to 99.0% after only the 4th cycle. The C?Si/C anode presented an improved capacity retention of 49.5% after the 39th cycle, compared with 46.0% for the P?Si/C anode after the 31st cycle, while maintaining the same ICE. Moreover, anodes prepared with 8 wt% P?Si/ C or C?Si/C and 92 wt% graphite (m-P-Si/C and m-C-Si/C, respectively) showed higher capacity retentions compared with pure Si/C anodes. The m-C-Si/C anode exhibited a higher capacity retention of 80.1% after the 40th cycle, compared with 71.2% for the m-P-Si/C anode. The m-C-Si/C anode also displayed an extremely low expansion rate and the majority of the expansion was elastically recovered. This C?Si/C composite provided a controllable means to modify the performance of LIBs by simple mixing with graphite
    corecore