A study of the density of states of ZnCoO:H from resistivity measurements

Understanding the electronic band structure and density of states (DOS) of a material and their relationship to the associated electronic transport properties is the starting point for optimizing the performance of a device and its technological applications. In a hydrogenated Zn_0.8Co_0.2O (ZnCoO:H) film with an inverted thin-film transistor structure, we found ambipolar behavior, which is shown in many field-effect devices based on graphene, graphene nanoribbons, and organic semiconductors. In this study, to obtain information on the DOS of ZnCoO:H to explain the ambipolar behavior in terms of the carrier density and type, resistivity and magnetoresistance measurements of a ZnCoO:H film were performed at 5 K. Our proposed DOS representation of ZnCoO:H explains qualitatively the experimental observations of carrier density modulation and ambipolar behavior. First-principles calculations of the DOS of ZnCoO:H were in good agreement with the proposed DOS representation. Through a comparison of first-principles calculations and experimental data, evidence for the existence of Co–H–Co in ZnCoO:H is suggested.

Ambipolar behavior in a hydrogenated Zn_0.8Co_0.2O (ZnCoO:H) film is investigated via resistivity and magnetoresistance measurements and first-principles calculations of the DOS. Evidence for the existence of Co–H–Co in ZnCoO:H is suggested.     

Low grade gastric mucosa associated lymphoid tissue lymphoma：Treatment strategies based on 10 year follow-up

AIM: To deduce strategic guidelines of gastric mucosa associated lymphoid tissue lymphoma (MALTOMA) by evaluating the long-term outcome of patients in respect to various treatment modalities. METHODS: A total of 55 patients with MALTOMA from May 1992 to August 2002 were retrospectively reviewed. RESULTS: Complete remission was obtained in 24 (82.8%) of 29 patients treated with anti Helicobacter pylori (H pylori) regimen only. The duration to reach complete remission was 12 months (85 percentile, 2-33 months). Five patients showed complete remission with radiation therapy (26-86 months). Two of them were H pylori treatment failure cases. CONCLUSION: H pylori eradication is an effective primary treatment option for low grade MALTOMA and radiation therapy could be considered in patients with no evidence of H pylori infection or who do not respond to H pylori eradication therapy 12 months after successful eradication.     

Noninvasive transcutaneous low frequency ultrasound enhances thrombolysis in peripheral and coronary arteries

Previous studies have shown that external ultrasound with low frequencies and high intensities can enhance thrombolytic drug-induced clot dissolution during in vitro experiments. In this series of studies, we evaluated the efficacy of peripheral and coronary thrombolysis in vivo in animals by using noninvasive transcutaneous ultrasound combined with thrombolytic drugs (streptokinase and tPA) and/or microbubbles agents (dodecafluoropentane [DDFP] and perfluorocarbon-exposed sonicated dextrose albumin [PESDA]). Thrombotic occlusions were induced in 74 rabbit iliofemoral arteries and 24 canine left anterior descending (LAD) coronary arteries in this in vivo study. By using the combination of transcutaneous ultrasound and streptokinase, the angiographic patency rate in rabbit iliofemoral arteries was higher (56%-100%) than with ultrasound (6%; P < or = 0.0036) and streptokinase alone (6%; P < or = 0.0012). Also, with transcutaneous ultrasound and microbubbles, the angiographic patency rates were 76%-100% as compared with ultrasound alone (0%, P < or = 0.0003) or microbubbles alone (9%, P < or = 0.0001). In the canine study of acute myocardial infarction, thrombolysis in myocardial infarction (TIMI) grade flow at 90 minutes in the tPA alone group was 0.92 +/- 1.4 as compared with 2.42 +/- 1.9 in the tPA plus transthoracic ultrasound group (P = 0.006). There was much improved reperfusion with tPA plus ultrasound as compared with tPA alone. In vivo animal studies demonstrate that noninvasive transcutaneous ultrasound can greatly enhance the effect of clot dissolution with thrombolytic drugs and/or microbubbles, and has the potential for clinical application as an adjunctive method to improve arterial thrombolysis.     

Arrhythmogenic right ventricular cardiomyopathy and sudden cardiac death in young Koreans.

The aim of this study was to assess the frequency and clinical characteristics of arrhythmogenic right ventricular cardiomyopathy (ARVC) in young victims of sudden cardiac death (SCD). From January 1999 to December 2000, postmortem studies were conducted in 38 cases of SCD (age < or =35 (27+/-7) years old, 26 male) from the Taegu-Kyungpook region of southeastern Korea. Cases of sudden infant death syndrome were excluded. The causes of SCD were ARVC in 42%, acute myocardial infarction in 11%, myocarditis in 11%, pulmonary embolism in 8%, hypertrophic cardiomyopathy in 5%, aortic rupture in 3%, aortic stenosis in 3%, and unknown in 18%. The mean age of the 16 ARVC victims was 27+/-5 years and 10 were male. None were competitive athletes, or had been suspected of having cardiovascular disease before death. SCD was not related to vigorous physical or competitive activity and occurred during sleep in 7 cases, during work in 4, during bathing in 2, while driving, praying and eating in 1 case each. ARVC is an important cause of SCD in young people in this area of Korea.     

Analysis of Pediatric Surgery Using the National Healthcare Insurance Service Database in Korea: How Many Pediatric Surgeons Do We Need in Korea?

BackgroundIn the past, general surgeons (GSs) without a pediatric surgical subspecialty often performed surgery on children and, even now, GSs are performing many pediatric surgeries. We aimed to investigate the involvement of pediatric surgeons (PSs) and GSs in pediatric surgery, compare the outcomes of surgery in the neonatal intensive care unit (NICU), and estimate the appropriate PS workforce in Korea.MethodsWe used surgical data from the National Health Insurance Service database that was collected from patients under the age of 19 years in hospitals nationwide from January 2002 to December 2017. In this database, we found 37 hospitals where PSs worked by using the index operation (congenital diaphragmatic hernia, esophageal atresia, hypertrophic pyloric stenosis, Hirschsprung''s disease, abdominal wall defect, jejunoileal atresia, malrotation, anorectal malformation, and biliary atresia). It was assumed that the surgery in the 37 hospitals was performed by PS and that the surgery in other hospitals was performed by GS. Mortality was analyzed to compare the outcomes of acute abdominal surgery in the NICU. We estimated the number of PS currently needed in Korea for each situation under the assumption that PS would perform all operations for the index operation, main pediatric diseases (index operation + gastroesophageal reflux disease, choledochal cyst, inguinal hernia, and appendicitis), acute abdominal surgery in the NICU, and all pediatric surgeries. Additionally, we estimated the appropriate number of PS required for more advanced pediatric surgery in the future.ResultsThe number of pediatric surgeries from 2002 to 2017 increased by 124%. Approximately 10.25% of the total pediatric surgeries were performed by PSs, and the percentage of the surgery performed by PSs increased from 8.32% in 2002 to 15.92% in 2017. The percentage of index operations performed by PSs annually was 62.44% in average. It was only 47.81% in 2002, and increased to 88.79% in 2017. During the last 5 years of the study period, the average annual number of surgeries for main pediatric diseases was approximately 33,228. The ratio of the number of surgeries performed by PS vs. GS steadily increased in main pediatric diseases, however, the ratio of the number of surgery performed by PS for inguinal hernia and appendicitis remained low in the most recent years. The percentage of the number of acute abdominal surgery performed by PS in the NICU was 44% in 2002, but it had recently risen to 89.7%. After 30 days of birth, mortality was significantly lower in all groups that were operated on by PS, rather than GS, during the last 5 years. In 2019, 49 PSs who were under the age of 65 years were actively working in Korea. Assuming that all pediatric surgeries of the patients under the age of 19 years should be performed by PS, the minimum number of PS currently required was about 63 if they perform all of the index operations, the main pediatric surgery was about 209, the NICU operation was about 63, and the all pediatric surgeries was about 366. Additionally, it was determined that approximately 165 to 206 PS will be appropriate for Korea to implement more advanced pediatric surgery in the future.ConclusionThe proportion of the pediatric surgery performed by PS rather than GS is increasing in Korea, but it is still widely performed by GS. PSs have better operative outcomes for acute abdominal surgery in the NICU than GSs. We believe that at least the index operation or the NICU operation should be performed by PS for better outcome, and that a minimum of 63 PSs are needed in Korea to do so. In addition, approximately 200 PSs will be required in Korea in order to manage main pediatric diseases and to achieve more advanced pediatric surgery in the future.