Chang Hwan Choi

Metal gate-HfO/sub 2/ MOS structures on GaAs substrate with and without Si interlayer

In this letter, we studied the effects of post-deposition anneal (PDA) time and Si interface control layer (ICL) on the electrical characteristics of the MOS capacitor with high-/spl kappa/ (HfO/sub 2/) material on GaAs. Thin equivalent oxide thickness (EOT<3 nm) with excellent capacitance-voltage (C-V) characteristics has been obtained. The thickness of the Si ICL and PDA time were correlated with C-V characteristics. It was found that high temperature Si ICL deposition and longer PDA time at 600/spl deg/C improved the C-V shape, leakage current, and especially frequency dispersion (<5%).

Development and Validation of Novel Diagnostic Criteria for Intestinal Behçet's Disease in Korean Patients With Ileocolonic Ulcers

OBJECTIVES:It is difficult to diagnose intestinal Behçets disease (BD) due to various extraintestinal manifestations emerging at different time points in the disease course and a lack of reliable diagnostic criteria. We conducted this study to develop and validate novel diagnostic criteria for intestinal BD.METHODS:Experts from three universities generated the preliminary diagnostic criteria for intestinal BD, and a consensus was reached using a modified Delphi method with 13 gastroenterologists participating. To validate the criteria, we recruited 12,850 consecutive patients who underwent colonoscopic examinations between January 2000 and December 2006 at Severance Hospital, Yonsei University, Seoul, Korea.RESULTS:The novel diagnostic criteria were developed on the basis of two aspects: colonoscopic findings and extraintestinal manifestations. Of the 12,850 patients, 280 with ileocolonic ulcers were enrolled for validation. At the time of initial colonoscopic examinations, patients were categorized for BD status into 4 groups: definite (84 patients), probable (67), suspected (15), and nondiagnostic (114). At the end of the follow-up period (mean, 50.9±25.7 months), intestinal BD was confirmed in 145 patients (51.8%)—84 (100%) from the definite group, 49 (73.1%) from the probable group, 10 (66.7%) from the suspected group, and 2 (1.8%) from the nondiagnostic group. The overall sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the diagnosis probability of these criteria were 98.6, 83.0, 86.1, 98.2, and 91.1%, respectively.CONCLUSIONS:These newly proposed, simple criteria might be useful in diagnosing intestinal BD, especially in patients with ileocolonic ulcers who do not fully satisfy the diagnostic criteria of systemic BD.

A randomized, double-blind, placebo-controlled multicenter trial of saccharomyces boulardii in irritable bowel syndrome: effect on quality of life.

Background Probiotics confer health benefits to the host. However, its clinical effect on irritable bowel syndrome (IBS) is controversial. Aims This study was aimed to evaluate the effects of Saccharomyces boulardii on quality of life (QOL) and symptoms in patients with diarrhea-predominant IBS or mixed-type IBS. Methods Sixty-seven patients with IBS were randomized either to receive S. boulardii at 2×1011 live cells as a daily dose (n=34), or placebo (n=33) for 4 weeks. IBS-QOL was assessed at the beginning and end of the treatment phase. IBS-related symptoms, bowel movement frequency, and stool consistency were recorded on a daily basis and assessed each week. Results The overall improvement in IBS-QOL was higher in S. boulardii group than placebo (15.4% vs 7.0%; P<0.05). All eight domains of IBS-QOL were significantly improved in S. boulardii group; however, placebo group only showed improvements in dysphoria and health worry. Composite scores for IBS symptoms were significantly reduced in both groups to a similar extent. Bowel frequency and stool consistency did not change in either group. Conclusions S. boulardii improved IBS-QOL better than placebo but was not superior for individual symptoms in patients with diarrhea-predominant IBS or mixed-type IBS.

The prevalence and efficacy of ganciclovir on steroid-refractory ulcerative colitis with cytomegalovirus infection: a prospective multicenter study

Background It remains controversial whether or not cytomegalovirus infection in patients with active ulcerative colitis reflects a nonpathogenic colonization or a pathogenic disease warranting antiviral therapy. Goals The aim of this study was to determine the prevalence of cytomegalovirus infection in patients with active ulcerative colitis and the therapeutic efficacy of ganciclovir against cytomegalovirus infection in patients with steroid-refractory ulcerative colitis. Study A prospective, multicenter study was conducted in 72 patients with moderate-to-severe ulcerative colitis who were treated with intravenous steroids. The presence of cytomegalovirus was evaluated serologically and histopathologic examination, including immunohistochemical staining. In patients with steroid-refractory ulcerative colitis, cytomegalovirus infections were treated with intravenous ganciclovir. In patients with steroid-responsive ulcerative colitis, steroid therapy was continued irrespective of cytomegalovirus infection. Results The evidence of cytomegalovirus infection was found in 31 patients (43%) with moderate-to-severe active ulcerative colitis. In patients with steroid-refractory ulcerative colitis, the cytomegalovirus infection rate increased to 67% (14 of 21). No significant clinical and endoscopic differences existed between patients with and without a cytomegalovirus infection; however, the amount of steroids used during the flare-up period was significantly higher in patients with a cytomegalovirus infection (P=0.013). Eleven of 14 patients (79%) with steroid-refractory ulcerative colitis and a cytomegalovirus infection improved with ganciclovir treatment. Cytomegalovirus infections in the steroid-responsive group (17 of 31) did not require ganciclovir therapy. Conclusions Cytomegalovirus infections are frequently observed in patients with moderate-to-severe ulcerative colitis, especially steroid-refractory ulcerative colitis. Ganciclovir was effective in patients with steroid-refractory ulcerative colitis who had a cytomegalovirus infection.

Efficacy, safety, and predictors of response to infliximab therapy for ulcerative colitis: A Korean multicenter retrospective study

Infliximab is currently used for the treatment of moderate‐to‐severe ulcerative colitis (UC) with an inadequate response to conventional agents. The efficacy and safety of infliximab in Korean patients with UC were assessed.

Incidence and clinical features of Clostridium difficile infection in Korea: a nationwide study

The incidence and severity of Clostridium difficile infections (CDI) have increased in Western countries. However, there are limited data regarding the epidemiology of CDI in Eastern countries. This nationwide study was conducted in 17 hospitals to determine temporal trends in CDI incidence (from 2004 to 2008) in South Korea. The total incidence of CDI in Korea was 1·7 cases/1000 adult admissions in 2004, and 2·7/1000 cases in 2008 (P = 0·028). When analysing the clinical features of 1367 CDI patients diagnosed in 2008, oral metronidazole was effective as a first-line treatment for CDI (61·9%). Relapse rate was 8·9% and complicated CDI was only observed in 3·6%. The incidence of CDI increased significantly in Korea from 2004 to 2008. Although the clinical features were milder than in Western countries, the increasing burden of CDI needs ongoing surveillance systems.

Structural advantage for the EOT scaling and improved electron channel mobility by incorporating dysprosium oxide (Dy/sub 2/O/sub 3/) into HfO/sub 2/ n-MOSFETs

A structural approach of fabricating laminated Dy₂O₃-incorporated HfO₂ multimetal oxide dielectric has been developed for high-performance CMOS applications. Top Dy₂O₃ laminated HfO₂ bilayer structure shows the thinnest equivalent oxide thickness (EOT) with a reduced leakage current compared to HfO₂. This structure shows a great advantage for the EOT scaling CMOS technology. Excellent electrical performances of the Dy₂O₃/HfO ₂ multimetal stack oxide n-MOSFET such as lower V_T, higher drive current, and an improved channel electron mobility are reported. Dy₂O₃/HfO₂ sample also shows a better immunity for V_t instability and less severe charge trapping characteristics. Two different rationed Dy ₂O₃/HfO₂ and HfO₂ n-MOSFET were measured by charge-pumping technique to obtain the interface state density (D_it), which indicates a reasonable and similar interface quality. Electron channel mobility is analyzed by decomposing into three regimes according to the effective field. Reduced phonon scattering is found to be the plausible mechanism for higher channel mobility

Prospective evaluation of the clinical utility of interferon-γ assay in the differential diagnosis of intestinal tuberculosis and Crohn's disease

Background: Distinguishing intestinal tuberculosis (ITB) from Crohns disease (CD) is challenging. This study prospectively evaluated the clinical utility of the QuantiFERON‐TB gold test (QFT) in the differential diagnosis of ITB and CD, and compared it with the clinical utility of the tuberculin skin test (TST). Methods: Patients with suspected ITB or CD on colonoscopic findings were enrolled from 13 hospitals in Korea between June 2007 and November 2008. A QFT and TST were performed. When the initial diagnosis was not confirmed, 2‐3 months of empiric antituberculous therapy was administered. Results: In all, 128 patients were analyzed; 64 patients had ITB and 64 patients had CD. The median age of patients with ITB was greater than the patients with CD (47 years versus 31 years, P < 0.001). The positive rate for the QFT and TST (≥10 mm) in patients with ITB was significantly higher than patients with CD (67% versus 9% and 69% versus 16%, respectively; P < 0.001). The QFT and TST had good agreement (&kgr; = 0.724, P < 0.001). The diagnostic validity of QFT in ITB had a 67% sensitivity, 90% specificity, 87% positive predictive value, and 73% negative predictive value. There was no difference in these parameters between the QFT and TST. The likelihood ratio for a positive QFT was higher than a positive TST in the diagnosis of ITB (7.1 and 4.4, respectively). Conclusions: The QFT is a limited but useful diagnostic aid in combination with the TST in the diagnosis of ITB. (Inflamm Bowel Dis 2011;)

Characterization and reliability of dual high-k gate dielectric stack (poly-Si-HfO 2 -SiO 2 ) prepared by in situ RTCVD process for system-on-chip applications

We investigate for the first time the possibility of integrating chemical vapor deposition (CVD) HfO/sub 2/ into the multiple gate dielectric system-on-a-chip (SoC) process in the range of 6-7 nm, which supports higher voltage (2.5-5 V operation/tolerance). Results show that CVD HfO/sub 2/-SiO/sub 2/ stacked gate dielectric (EOT =6.2 nm) exhibits lower leakage current than that of SiO/sub 2/ (EOT =5.7 nm) by a factor of /spl sim/10/sup 2/, with comparable interface quality (D/sub it//spl sim/1/spl times/10/sup 10/ cm/sup -2/eV/sup -1/). The presence of negative fixed charge is observed in the HfO/sub 2/-SiO/sub 2/ gate stack. In addition, the addition of HfO/sub 2/ on SiO/sub 2/ does not alter the dominant conduction mechanism of Fowler-Nordheim tunneling in the HfO/sub 2/-SiO/sub 2/ gate stack. Furthermore, the HfO/sub 2/-SiO/sub 2/ gate stack shows longer time to breakdown T/sub BD/ than SiO/sub 2/ under constant voltage stress. These results suggest that it may be feasible to use such a gate stack for higher voltage operation in SoC, provided other key requirements such as V/sub t/ stability (charge trapping under stress) can be met and the negative fixed charge eliminated.

Patients with Crohn's disease on anti-tumor necrosis factor therapy are at significant risk of inadequate response to the 23-valent pneumococcal polysaccharide vaccine

BACKGROUND/AIMS The effect of immunosuppressants on the efficacy of a variety of vaccines is a controversial issue in patients with inflammatory bowel disease (IBD). In this study we determined whether specific immunosuppressants impair the serological response to the standard 23-valent pneumococcal polysaccharide vaccine (PPSV23) in a large cohort of patients with Crohns disease (CD). METHODS This was a multi-center, prospective observational study of adult patients with CD at 15 academic teaching hospitals in Korea. The study population received one intramuscular injection of PPSV23. Anti-pneumococcal IgG antibody titers were measured by immunoassay prior to and 4weeks after vaccination. All vaccination-related adverse events and the effect of the vaccine on disease activity were also evaluated. RESULTS The overall serological response rate was 67.5% (133/197). The serological response rate was significantly lower in patients on anti-tumor necrosis factor (anti-TNF) therapy (50.0% on anti-TNF alone; 58.0% on anti-TNF combined with an immunomodulator, IM) than patients on 5-aminosalicylate (78.4%; all P-values vs. 5-aminosalicylate<0.05); 45.6% (41/90) of patients on anti-TNF therapy were not protected against PPSV23. IM did not affect the immunologic response to the vaccine. Female gender and anti-TNF therapy were significant predictors of non-response to the vaccine (odds ratio [OR] 2.316, P=0.015; OR 2.582, P=0.048, respectively). Vaccination was generally safe and tolerated by all patients. CONCLUSIONS Patients with CD on anti-TNF therapy are at significant risk of an inadequate response to PPSV23. The pneumococcal vaccination strategy should be optimized for patients with CD on anti-TNF therapy.