1,427 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
Could HBx Protein Expression Affect Signal Pathway Inhibition by Gefitinib or Selumetinib, a MEK Inhibitor, in Hepatocellular Carcinoma Cell Lines?
Hepatitis B virus X (HBx) protein has been known to play an important role in development of hepatocellular carcinoma (HCC). The aim of this study is to find out whether HBx protein expression affects antiproliferative effect of an epidermal growth factor receptor-tyrosine kinase (EGFR-TK) inhibitor and a MEK inhibitor in HepG2 and Huh-7 cell lines. We established HepG2 and Huh-7 cells transfected stably with HBx gene. HBx protein expression increased pERK and pAkt expression as well as β-catenin activity in both cells. Gefitinib (EGFR-TK inhibitor) inhibited pERK and pAkt expression and β-catenin activity in both cells. Selumetinib (MEK inhibitor) reduced pERK level and β-catenin activity but pAkt expression was rather elevated by selumetinib in these cells. Reduction of pERK levels was much stronger with selumetinib than gefitinib in both cells. The antiproliferative efficacy of selumetinib was more potent than that of gefitinib. However, the antiproliferative effect of gefitinib, as well as selumetinib, was not different between cell lines with or without HBx expression. Signal pathway activation by HBx might not be strong enough to attenuate the antiproliferative effect of EGFR-TK inhibitor. Future experiments are needed to understand the role of HBx protein expression in HCC treatment using molecular targeting agent
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
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
Clinical characteristics of genital chlamydia infection in pelvic inflammatory disease
Abstract
Background
Chlamydia infection in acute pelvic inflammatory disease (PID) is associated with serious complications including ectopic pregnancy, tubal infertility, Fitz-Hugh-Curtis syndrome and tubo-ovarian abscess (TOA). This study compared clinical and laboratory data between PID with and without chlamydia infection.
Methods
The medical records of 497 women who were admitted with PID between 2002 and 2011 were reviewed. The patients were divided into two groups (PID with and without chlamydia infection), which were compared in terms of the patients\u2019 characteristics, clinical presentation, and laboratory findings, including inflammatory markers.
Results
The chlamydia and non-chlamydia groups comprised 175 and 322 women, respectively. The patients in the chlamydia group were younger and had a higher rate of TOA, a longer mean hospital stay, and had undergone more surgeries than the patients in the non- chlamydia group. The erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and CA-125 level were higher in the chlamydia group than in the non-chlamydia group, but there was no significant difference in the white blood cell count between the two groups. The CA-125 level was the strongest predictor of chlamydia infection, followed by the ESR and CRP level. The area under the receiving operating curve for CA-125, ESR, and CRP was 0.804, 0.755, and 0.663, respectively.
Conclusions
Chlamydia infection in acute PID is associated with increased level of inflammatory markers, such as CA-125, ESR and CRP, incidence of TOA, operation risk, and longer hospitalization
Serum gamma-glutamyltransferase is not associated with subclinical atherosclerosis in patients with type 2 diabetes
BACKGROUND: This study investigated the association between serum gamma-glutamyltransferase (GGT) level and subclinical atherosclerosis in patients with type 2 diabetes. METHODS: This cross-sectional study involved 1024 patients with type 2 diabetes mellitus. Measurement of brachial-ankle pulse wave velocity (baPWV; as a marker of arterial stiffness) and an ultrasound assessment of carotid atherosclerosis were performed. Subclinical atherosclerosis was defined by the presence of a high baPWV (≥1720 cm/s), carotid atherosclerosis (intima-media thickness >0.8 mm or the presence of plaques), and carotid stenosis (≥50 % of luminal narrowing). The subjects were stratified into quartiles according to GGT level, and the relationship between GGT level and subclinical atherosclerosis was analysed. RESULTS: Serum GGT levels were closely associated with obesity, atherogenic dyslipidemia, and metabolic syndrome. However, serum GGT levels did not show a linear association with baPWV, carotid intima-media thickness, or plaque grade. The prevalence of high baPWV, carotid atherosclerosis, and carotid stenosis did not differ between the quartiles in men and women. Multivariate logistic regression analyses revealed no association between GGT level and high baPWV, carotid atherosclerosis, and carotid stenosis, either as continuous variables or quartiles. CONCLUSIONS: Serum GGT levels were significantly associated with obesity, atherogenic dyslipidaemia, and metabolic syndrome, but not with the early and late stages of atherosclerotic vascular changes, in patients with type 2 diabetes. Serum GGT level may not be a reliable marker of subclinical atherosclerosis in type 2 diabetes
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