Recent Structure development of poly(vinylidene fluoride)-based piezoelectric nanogenerator for self-powered sensor

As the internet of things (IoT) era approaches, various sensors, and wireless electronic devices such as smartphones, smart watches, and earphones are emerging. As the types and functions of electronics are diversified, the energy consumption of electronics increases, which causes battery charging and maintenance issues. The piezoelectric nanogenerator (PENG) received great attention as an alternative to solving the energy issues of future small electronics. In particular, polyvinylidene fluoride (PVDF) piezoelectric polymer-based PENGs are strong potential candidate with robust mechanical properties and a high piezoelectric coefficient. In this review, we summarize the recent significant advances of the development of PVDF-based PENGs for self-powered energy-harvesting systems. We discuss the piezoelectric properties of the various structures of PVDF-based PENGs such as thin film, microstructure, nanostructure, and nanocomposite. © 2020 by the authors.1

Theoretical study of the ammonia nitridation rate on an Fe (100) surface: A combined density functional theory and kinetic Monte Carlo study

Ammonia (NH[subscript 3]) nitridation on an Fe surface was studied by combining density functional theory (DFT) and kinetic Monte Carlo (kMC) calculations. A DFT calculation was performed to obtain the energy barriers (E[subscript b]) of the relevant elementary processes. The full mechanism of the exact reaction path was divided into five steps (adsorption, dissociation, surface migration, penetration, and diffusion) on an Fe (100) surface pre-covered with nitrogen. The energy barrier (E[subscript b]) depended on the N surface coverage. The DFT results were subsequently employed as a database for the kMC simulations. We then evaluated the NH[subscript 3] nitridation rate on the N pre-covered Fe surface. To determine the conditions necessary for a rapid NH[subscript 3] nitridation rate, the eight reaction events were considered in the kMC simulations: adsorption, desorption, dissociation, reverse dissociation, surface migration, penetration, reverse penetration, and diffusion. This study provides a real-time-scale simulation of NH[subscript 3] nitridation influenced by nitrogen surface coverage that allowed us to theoretically determine a nitrogen coverage (0.56 ML) suitable for rapid NH[subscript 3] nitridation. In this way, we were able to reveal the coverage dependence of the nitridation reaction using the combined DFT and kMC simulations.Korea (South). Ministry of Education, Science and Technology (MEST) (National Research Foundation of Korea. 2011-0028612

Macular Infarction Associated with Reactive Arthritis

A 53-year-old woman visited the Department of Rheumatology with a chief complaint of a 3-day history of fever and chills and also presented with pain occuring in both knees at the time of outpatient visit. Based on rheumatologic and hematological lab studies, ultrasonography, and a needle aspiration biopsy of the articular cavity, the patient was diagnosed with reactive arthritis. On hospitalization day 3, consultation with the Department of Ophthalmology was requested regarding decreased visual acuity lasting for 3 days. Upon ophthalmologic examination, the corrected visual acuity was 0.1 in the right eye and 0.05 in the left eye. Upon slit lamp microscopy, there were no abnormal findings in the anterior segment. Upon fundus examination, however, there were yellow-white lesions in the macular area of both eyes. Fluorescein angiographywas performed to assess the macular lesions, and the findings were suggestive of macular infarction in both eyes. Due to a lack of other underlying disease, a past surgical history, and a past history of drug administration, the patient was diagnosed with macular infarction in both eyes associated with reactive arthritis. To date, there have been no other such cases reported. In a patient with reactive arthritis, we experienced a case of macular infarction in both eyes, which occurred without association with a past history of specific drug use or underlying disease. Herein, we report our case, with a review of the literature

Implementation of a Videoconferencing System between Multiple Family Medicine Departments

Attending conferences is important for doctors and residents in family medicine. Nevertheless, departments of family medicine at many hospitals find it difficult to hold regular conferences. Holding joint videoconferences between Family Medicine Departments of several hospitals through a videoconferencing system could solve this problem. Therefore, Family Medicine Departments of Seoul National University Hospital, Seoul National University Bundang Hospital, and Kangwon National University Hospital decided to hold regular joint videoconferences via a videoconferencing system. Eighty-one joint videoconferences were held from April 1 to October 29, 2010. PowerPoint slideshows were transferred to the other two locations in the same resolution as presenter's monitor. Image and voice of the speaker were transferred in real time and in acceptable quality. Joint videoconferences are feasible, satisfactory and useful for medical education, especially when individual family medicine departments are small and lack resources to hold face-to-face conferences. We expect that more family medicine departments will choose to participate in implementing similar joint videoconferencing systems in the future

Valsalva Retinopathy Associated With an Oratorical Contest

A 17-year-old man presented to us with a chief complaint of decreased visual acuity accompanied by central scotoma. There was nothing unusual in his medical history other than a recent oratorical contest. At the time of initial diagnosis, the corrected visual acuity was 20/20 in the right eye and 20/100 in the left eye. No significant findings were apparent on ophthalmic evaluation. On fundoscopy, there was a dumbbell-shaped macular bleed with a well-defined margin in the left eye. The clinical course was closely monitored along with drug therapy. Four weeks post presentation, the pre-retinal hemorrhage had nearly resolved. On fluorescein angiography, no significant findings were observed. In the left eye, the corrected visual acuity had improved to 20/25. Valsalva retinopathy is a pathology that occurs when a sudden increase in intra-thoracic pressure or abdominal pressure occurs in an otherwise healthy person. Here we report a case of Valsalva retinopathy occurring following an oratorical contest along with a review of the relevant literature

STAT1 and Nmi are downstream targets of Ets-1 transcription factor in MCF-7 human breast cancer cell

AbstractEts-1 is a cellular homologue of the product of the viral ets oncogene of the E26 virus, and it functions as a tissue-specific transcription factor. It plays an important role in cell proliferation, differentiation, lymphoid cell development, transformation, angiogenesis, and apoptosis. Ets-1 controls the expression of critical genes involved in these processes by binding to ets binding sites present in the transcriptional regulatory regions. Here, we transiently overexpressed Ets-1 in MCF-7 and comprehensively searched for potential downstream targets of Ets-1 by cDNA microarray analysis. The expressions of several interferon-related genes including STAT1 and Nmi were augmented by the overexpression of Ets-1. RT-PCR and Western blotting confirmed the increase in the levels of STAT1 and Nmi mRNA and protein. In contrast, Ets-1 siRNA decreased the expression of STAT1 and Nmi proteins. As in our transient transfection experiments, stable overexpression of Ets-1, also increased the protein expression of STAT1 and Nmi in MCF-7 cells. Taken together, our results indicate that STAT1 and Nmi are downstream targets of Ets-1 in MCF-7 human breast cancer cells

Benign Schwannoma of the Liver: A Case Report

A primary benign schwannoma of the liver is extremely rare. Only nine cases have been reported in the medical literature worldwide and no case has been reported in Korea previously. A 36-yr-old woman was admitted to our hospital with vague epigastric pain. The ultrasound and computed tomography scan revealed a multi-septated cystic mass in the right lobe of the liver. The mass was resected; it was found to be a 5 × 4 × 2 cm mass filled with reddish yellow fluid. The histological examination confirmed the diagnosis of a benign schwannoma, proven by positive immunoreaction with the neurogenic marker S-100 protein and a negative response to CD34, CD117 and smooth muscle actin. This is the first report of a benign schwannoma of the liver parenchyma in a Korean patient

Cardiac tamponade caused by tuberculosis pericarditis in renal transplant recipients

A 50-year-old male, renal transplant recipient, was admitted with fever and chest discomfort. At admission, chest radiologic finding was negative and echocardiography showed minimal pericardial effusion. After 2 days of admission, chest pain worsened and blood pressure fell to 60/40 mmHg. Emergency echocardiography showed a large amount of pericardial effusion compressing the entire heart. Pericardiocentesis was performed immediately. Mycobacterium tuberculosis was isolated from pericardial fluid. Tuberculosis pericarditis should be considered as the cause of cardiac tamponade in renal transplant recipients, even with the absence of pericardial effusion in the initial study or suggestive history

Potential impact of 2018 Korean Society of Hypertension guidelines on Korean population: a population-based cohort study

Abstract Background The Korean Society of Hypertension (KSH) revised the local guidelines for hypertension in 2018. The present study sought to evaluate the potential impact of the 2018 KSH guidelines on hypertension management status among the Korean population in terms of prevalence of hypertension, antihypertensive medical treatment recommendations, and control status in Korean adults. Methods We used data from the Korea National Health and Nutrition Examination Survey to estimate the number and percentage of Korean adults who have hypertension according to blood pressure (BP) classification, are recommended to receive antihypertensive medical treatment, and are receiving medical treatment and have BP in the optimal range according to the new recommendations. Adults aged 30 years or older who participated in the survey between 2013 and 2015 were selected for this study. Results The prevalence of hypertension was 30.5% among Korean adults aged 30 years or older. The percentage of subjects who are recommended to be treated with antihypertensive medications substantially increased from 32.5 to 37.8%, which translates to 1.6 million adults. Among the hypertensive patients who were receiving medical treatment, 38.6% were shown to have adequate BP levels as recommended by the 2018 KSH guidelines compared with 51.8% according to the previous 2013 guidelines. Conclusions The present study reports the potential impact of the 2018 KSH guidelines on the prevalence of hypertension, antihypertensive medical treatment recommendations, and control status for Korean adults. The 2018 KSH guidelines recommend more intensive BP control compared with previous guidelines. This study suggests that there is large scope for improvement in hypertension management in the Korean population