634 research outputs found
Extraction of Prosodic Information from Spoken Word for Synthesizing Korean Speech
This paper describes a study on prosodic information extracted from spoken Korean words, as a preliminary study to synthesize natural Korean speech. We investigated prosodic features-duration, amplitude and pitch-of some 500 words, of which selection was based on appearing frequency in Korean elementary school textbooks. Some results on word-based prosodic information are deduce
Switchable π-electronic network of bis(α-oligothienyl)-substituted hexaphyrins between helical versus rectangular circuit
The switching phenomena of conformation with π-electronic network through deprotonation-protonation processes were investigated by employing a series of 5, 20-bis(α-oligothienyl) substituted hexaphyrins(1.1.1.1.1.1). They showed significant changes in the absorption and emission spectra with deprotonation, and returned to the initial state with protonation. Through NMR measurements and single crystal X-ray diffraction analysis, we found that the 5, 20-bis(α-oligothienyl) substituted hexaphyrins, which possess acyclic, helical electronic networks involving oligothienyl chains in dumbbell conformations (type-I) in a neutral form, underwent effective deprotonation upon treatment with tetrabutylammonium fluoride (TBAF) to generate the corresponding dianions, which display cyclic electronic networks with enhanced aromaticity in rectangular conformations (type-II). Our quantum calculation results provide an unambiguous description for the switchable conformation and π-conjugation, which revealed that a deprotonation-induced enhanced aromatic conjugation pathway is involved in the switchable π-electronic network
Nanopores of carbon nanotubes as practical hydrogen storage media
We report on hydrogen desorption mechanisms in the nanopores of multiwalled carbon nanotubes (MWCNTs). The as-grown MWCNTs show continuous walls that do not provide sites for hydrogen storage under ambient conditions. However, after treating the nanotubes with oxygen plasma to create nanopores in the MWCNTs, we observed the appearance of a new hydrogen desorption peak in the 300–350 K range. Furthermore, the calculations of density functional theory and molecular dynamics simulations confirmed that this peak could be attributed to the hydrogen that is physically adsorbed inside nanopores whose diameter is approximately 1 nm. Thus, we demonstrated that 1 nm nanopores in MWCNTs offer a promising route to hydrogen storage media for onboard practical applications
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Controlling the Magnetic Anisotropy of the van der Waals Ferromagnet Fe3GeTe2 through Hole Doping.
Identifying material parameters affecting properties of ferromagnets is key to optimized materials that are better suited for spintronics. Magnetic anisotropy is of particular importance in van der Waals magnets, since it not only influences magnetic and spin transport properties, but also is essential to stabilizing magnetic order in the two-dimensional limit. Here, we report that hole doping effectively modulates the magnetic anisotropy of a van der Waals ferromagnet and explore the physical origin of this effect. Fe3-xGeTe2 nanoflakes show a significant suppression of the magnetic anisotropy with hole doping. Electronic structure measurements and calculations reveal that the chemical potential shift associated with hole doping is responsible for the reduced magnetic anisotropy by decreasing the energy gain from the spin-orbit induced band splitting. Our findings provide an understanding of the intricate connection between electronic structures and magnetic properties in two-dimensional magnets and propose a method to engineer magnetic properties through doping
Response to hepatitis B vaccination in patients with inflammatory bowel disease: a prospective observational study in Korea
Background/Aims Testing for hepatitis B virus (HBV) serologic markers and appropriate vaccination are required in the management of inflammatory bowel disease (IBD) patients. We evaluated immunogenicity for HBV in IBD patients and the response to the HBV vaccination. Methods From May 2014 to August 2016, patients diagnosed with IBD were prospectively included and evaluated for antibody to hepatitis B surface antigen, antibody to hepatitis B core antigen, and antibody to hepatitis B surface antigen. Among the 73 patients who were confirmed with nonimmunity to HBV, 44 patients who had completed the 3-dose HBV vaccination series received a single booster vaccination, while 29 patients who had not completed the vaccinations series or were unsure of receiving the vaccination received a full vaccination series. Results An optimal response was obtained in 70.5% of the patients in the booster group, and 89.7% of the patients in the full vaccination group. Age younger than 26 years (odds ratio [OR], 6.01; 95% confidence interval [CI], 1.15–31.32; P=0.033) and a complete previous vaccination series (OR, 0.15; 95% CI, 0.03–0.80; P=0.026) were associated with optimal vaccine response. Previous complete vaccination series (OR, 0.11; 95% CI, 0.02–0.73; P=0.022) was the only predictive factor for lower compliance. Conclusions The response to the HBV vaccination was lower in patients older than 26 years and for those patients with a complete vaccination history. Since patients with a complete vaccination history also had poor compliance, serum HBV-titers should be checked more thoroughly, and a full vaccination series should be administered in cases when there is a negative response to the booster vaccination
Prevalence of human papillomavirus infection and genotype distribution among high-risk Korean women for prospecting the strategy of vaccine development
We investigated the prevalence of human papillomavirus (HPV) infection and the distribution of high-risk HPV genotypes among 2,308 high-risk Korean women to predict how much the current prophylactic HPV vaccines might affect the prevention of cervical cancer in Korea. HPV DNA was detected in 939 women (40.7%) but only one-third of women were positive for HPV-16 and/or HPV-18, the genotypes used for developing the HPV vaccines. Thus, the development of area-specific HPV vaccines based on dominant HPV genotypes in our country is needed for preventing HPV infection and the development of premalignant lesions in the cervix of Korean women
Effectiveness of MR Urography in the Evaluation of Kidney which Failed to Opacify during Excretory Urography: Comparison with Ultrasonography
Successful Endourologic Management of Lower Pole Moiety Ureteropelvic Junction Obstruction in a Partially Duplicated Collecting System
We present two cases of symptomatic lower pole moiety ureteropelvic junction obstruction (UPJO) in a partially duplicated collecting system that were successfully treated with minimally invasive endourologic procedures. In the first case, we performed retrograde endopyelotomy with the Acucise® ureteral cutting balloon device, and in the latter case, we performed percutaneous nephrolithotomy and antegrade endopyelotomy because of the presence of multiple renal stones. Subsequent intravenous pyelography confirmed marked resolution of the obstruction, and both patients remained asymptomatic during 1 year of follow-up
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