76 research outputs found

    Conical Ground Helical Antenna with Feed-Through Insulator for High-Power Microwave Applications

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    In this paper, a novel helical antenna for high-power microwave is proposed. The proposed antenna is intended to demonstrate improved power handling capacity without any deterioration in matching characteristics, gain, and axial ratio. The proposed antenna with a long helix structure is investigated in order to achieve high gain and a relatively wide impedance bandwidth. By increasing the distance between the helix and the ground plane, an improved power handling capacity is obtained, and the impedance matching problem caused by the proposed method is addressed with the use of a feed-through insulator. In addition, a conical-shaped ground is used to compensate for the gain reduction by increasing the distance between the helix and the ground plane. As a result, the proposed antenna exhibits a gain exceeding 11 dBi and an axial ratio of less than 2 dB within the frequency range of 0.86–1.09 GHz. In addition, its power handling capacity exceeds 50 MW for a 0.7-ns input pulse length in air conditions

    Peritoneal carcinomatosis with desmoplasia and osseous metaplasia mimicking encapsulating peritoneal sclerosis in a cat: case report

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    A 13-year-old neutered male Korean short-hair cat presented with anorexia, lethargy, and a severely distended abdomen, suggestive of ascites. Abdominocentesis yielded serosanguineous fluid. A subsequent diagnostic workup, including blood tests, ascitic fluid analysis, imaging studies [radiography, ultrasound, and computed tomography (CT)], and histopathological examination, was performed to identify the underlying cause. Imaging studies revealed characteristics of encapsulating peritoneal sclerosis (EPS) such as peritoneal thickening, fat stranding, and calcification. During laparotomy, fibrous membranes encapsulating the abdominal organs and ascites were observed, and multiple calcified regions were detected on the abdominal wall. Histopathological analysis confirmed the diagnosis of poorly differentiated invasive malignant neoplasms, which were further classified as carcinomatosis based on positive cytokeratin and negative vimentin immunohistochemistry results. To our knowledge, this is the first report of sclerosing peritoneal carcinomatosis with osseous metaplasia in a cat

    Characteristics of Ba(Zr0.1Ce0.7Y0.2)O3-δ nano-powders synthesized by different wet-chemical methods for solid oxide fuel cells

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    This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2017R1A6A3A03004416) and (NRF-2015M1A2A2056833).Ba(Zr0.1Ce0.7Y0.2)O3-δ nano-particles were prepared by different wet-chemical synthesis, Pechini (BZCY(P)) and co-precipitation (BZCY(C)), respectively. The BZCY(C) powders have a particle size in range of about 50~150 nm, which is smaller than the BZCY(P) powders with about 500~900 nm. Both the BZCY materials show perovskite structures, but there are impurities in the BZCY (P). Moreover, the electrolyte density was higher in the BZCY (C) than the BZCY (P). The single cells with BZCY (C) electrolytes exhibited about 0.23 W cm−2 at 600 °C and about 0.31 W cm−2 at the same temperature were obtained when the anode-functional layer was introduced between the anode and electrolyte. Thus, the BZCY prepared by carbonate-derived co-precipitation method can be more favorable for high-purity and dense electrolytes in the solid oxide fuel cells than the BZCY prepared by Pechini method.PostprintPeer reviewe

    Caloric restriction of db/db mice reverts hepatic steatosis and body weight with divergent hepatic metabolism

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    Non-alcoholic fatty liver disease (NAFLD) is one of the most frequent causes of liver disease and its prevalence is a serious and growing clinical problem. Caloric restriction (CR) is commonly recommended for improvement of obesity-related diseases such as NAFLD. However, the effects of CR on hepatic metabolism remain unknown. We investigated the effects of CR on metabolic dysfunction in the liver of obese diabetic db/db mice. We found that CR of db/db mice reverted insulin resistance, hepatic steatosis, body weight and adiposity to those of db/m mice. H-NMR- and UPLC-QTOF-MS-based metabolite profiling data showed significant metabolic alterations related to lipogenesis, ketogenesis, and inflammation in db/db mice. Moreover, western blot analysis showed that lipogenesis pathway enzymes in the liver of db/db mice were reduced by CR. In addition, CR reversed ketogenesis pathway enzymes and the enhanced autophagy, mitochondrial biogenesis, collagen deposition and endoplasmic reticulum stress in db/db mice. In particular, hepatic inflammation-related proteins including lipocalin-2 in db/db mice were attenuated by CR. Hepatic metabolomic studies yielded multiple pathological mechanisms of NAFLD. Also, these findings showed that CR has a therapeutic effect by attenuating the deleterious effects of obesity and diabetes-induced multiple complications

    Primary Cardiac Lymphoma Presenting With Atrioventricular Block

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    Primary cardiac lymphomas (PCL) are extremely rare. Clinical manifestations may be variable and are attributed to location. Here, we report on a case of PCL presenting with atrioventricular (AV) block. A 55 year-old male had experienced chest discomfort with unexplained dyspnea and night sweating. His initial electrocardiogram (ECG) revealed a first degree AV block. Along with worsening chest discomfort and dyspnea, his ECG changed to show second degree AV block (Mobitz type I). Computed tomography (CT) scan showed a cardiac mass (about 7 cm) and biopsy was performed. Pathologic finding confirmed diffuse large B-cell lymphoma. The patient was treated with multi-drug combination chemotherapy (R-CHOP: Rituximab, cyclophoshamide, anthracycline, vincristine, and prednisone). After treatment, ECG changed to show normal sinus rhythm with complete remission on follow-up CT scan

    Physiological Changes in Jeju Crossbred Riding Horses by Swim Training

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    The changes in physiologic parameters by swim exercise duration were examined in five female well-trained Jeju crossbred riding horses that had riding experience of more than three years without swim training experience. The horses were performed with swim exercise for 10 min (60.0 m/min) once a day for 14 days. Physiologic characteristics and haematic parameters were measured before swimming, immediately after swimming, and after a 10 min rest at first day (D0), 7 days (D7), and 14 days (D14) of training. After 14 days of swim training, heart rate (p<0.05), blood glucose (p<0.05), lactate concentration (p<0.001), packed cell volume (p<0.01), and hemoglobin (p<0.01) measured immediately after swim and after 10 min rest showed significant lower values than those of D0. The results illustrate the benefits of swim training for riding horses and the need for the establishment of swimming routines of appropriate duration and intensity to maximize the advantages of swim training

    Supramolecular hyper-branch polymerization using Host-guest interaction

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    Among supramolecular chemistry, host-guest interactions describe two molecules that interact based on non-covalent bonds. Non-covalent bonds are weaker than covalent bonds but are used to make large molecules such as proteins and nucleic acids that are important for biochemical processes. In this work, we designed AOCB[6]-PY, in which host and guest molecules are linked, to become a tunable hyperbranched polymer through host-guest interactions. Cucurbit [6] uril (CB [6]) is a non-toxic host material that does not fully interact with the guest material pyridine at room temperature, but at high temperatures the activity of the host and guest molecules increases, forming a hyperbranched polymer. Therefore, we developed reusable hyperbranched polymers using temperature-dependent host-guest interactions to achieve antimicrobial polymer coatings
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