Young Seok Lee

Adhesion enhancement of ion beam mixed Cu/Al/polyimide

Cu (400 A)/polyimide was mixed with 80 keV Ar+ and N2+ from 1.0×1015 to 2.0×1016 ions/cm2. The same processes were repeated for the Cu (400 A)/Al (50 A)/polyimide system which has Al as a buffer layer. The quantitative adhesion strength was measured by a standard scratch test. X-ray photoelectron spectroscopy was employed to investigate the change in the chemical bonds of the ion beam mixed polyimide substrate and the intermediate effects for the adhesion enhancement in Cu/Al/polyimide. Two distinct tendencies are observed in the adhesion strength: Cu/Al/polyimide is more adhesive than Cu/polyimide after ion beam mixing, and N2+ ions are more effective in the adhesion enhancement than Ar+. The formation of an interlayer compound of CuAl2O4 accounts for the former, while the latter is understood by the fact that N2+ ions produce more pyridinelike moiety, amide group and tertiary amine moiety which are known as adhesion promoters.

Effect of Pb(Yb1/2Nb1/2)O3 on structural and piezoelectric properties of Pb(Zr0.52Ti0.48)O3 ceramics

Solid solutions of xPb(Yb1/2Nb1/2)O3–(1−x)Pb(Zr0.52Ti0.48)O3, x=0–0.25, were investigated from the viewpoint of structural, dielectric, and piezoelectric properties. With increasing Pb(Yb1/2Nb1/2)O3 content (x), the structural change occurred from the tetragonal to the pseudocubic phase at room temperature. The morphotropic phase boundary (MPB) between the tetragonal and pseudocubic phases was shown in the region of x=0.05–0.10. Polarization and electric-field-induced strain exhibited a maximum at the composition near MPB. It may be concluded that both the ease of domain switching and the enhanced polarization play an important role in bringing about large electric-field-induced strain. At this composition, the remnant polarization and coercive field were 29.5 μC/cm2 and 4.5 kV/cm at 17 kV/cm, respectively, and a maximum electric-field-induced strain of 0.97×10−3 at 25 kV/cm was obtained. Also, the electromechanical coupling coefficient (Kp) and mechanical quality factor (Qm) were 0.47 and 65, respectively.

Performance of REBA MTB-XDR to detect extensively drug-resistant tuberculosis in an intermediate-burden country

Extensively drug-resistant tuberculosis (XDR-TB) is a serious worldwide problem. The REBA MTB-XDR (REBA-XDR) was recently developed in Korea to detect resistance to ofloxacin, kanamycin, and streptomycin. The aim of this study is to evaluate the diagnostic accuracy of the REBA-XDR. We prospectively enrolled 104 patients with acid-fast bacilli smear-positive specimens between July 2010 and January 2013. Performance characteristics were compared between REBA-XDR and conventional drug-susceptibility testing. The sensitivity values of REBA-XDR for detecting resistance to ofloxacin, kanamycin, and streptomycin were 66.7%, 90.9%, and 60.0%, and the specificity values were 93.3%, 93.5%, and 85.4%, respectively. The positive predictive values were 62.5%, 62.5%, and 40.9%, and the negative predictive values were 94.3%, 98.9%, and 92.7%, respectively. Accuracy was 89.4%, 93.3%, and 81.7%, respectively. REBA-XDR seems to be a useful kit for ruling in XDR-TB in intermediate-burden countries, and especially useful for detecting kanamycin resistance.

New scoring system for the differentiation of chronic obstructive pulmonary disease and asthma

It remains difficult to differentiate between chronic obstructive pulmonary disease (COPD) and asthma in clinical practice, especially in a primary care setting. The purpose of this study was to develop a new scoring system for differentiating between COPD and asthma, and to evaluate its effectiveness.

Diagnostic usefulness of the GenoType MTBDRplus assay for detecting drug-resistant tuberculosis using AFB smear-negative specimens with positive TB-PCR result

Abstract Background The aim of this study was to evaluate the diagnostic accuracy of the GenoType MTBDRplus assay in detecting drug-resistant tuberculosis (DR-TB) by using acid-fast bacilli (AFB) smear-negative specimens with positive TB-PCR results. Methods The MTBDRplus assay was performed with 2 different categories of 117 samples, including AFB smear-positive specimens (nu2009=u200953) and AFB smear-negative specimens (nu2009=u200964), which exhibited positive TB-PCR results, at a single institution. The results were retrospectively compared with the results of the phenotypic drug susceptibility test (DST), for reference. Results A total of 105 tests were finally analyzed. Of these, 54 tests were conducted using AFB smear-negative specimens with positive TB-PCR results. The MTBDRplus assay for these 54 samples demonstrated a sensitivity of 100%, specificity of 98%, positive predictive value (PPV) of 75%, and negative predictive value (NPV) of 100% in detecting rifampicin resistance. With these same species, the sensitivity, specificity, PPV, and NPV values for the MTBDRplus assay were 83.3%, 97.9%, 83.3%, and 97.9%, respectively, for the detection of isoniazid resistance. The overall correlation between the MTBDRplus assay and phenotypic DST demonstrated excellent agreement for detection of rifampicin resistance (κu2009=u20090.847) and for detection of INH resistance (κu2009=u20090.812), respectively. Conclusions The MTBDRplus assay can be used effectively even on AFB smear-negative specimens from TB patients, when the TB-PCR is positive. This result might help clinicians to manage patients with suspected DR-TB in difficult situations.