Sang-Kyun Sohn

Optical properties of the BaMgAl10O17:Eu2+ phosphor coated with SiO2 for a plasma display panel

In order to improve the luminance of blue emission of the plasma display panel (PDP), BaMgAl10O17:Eu2+ (BAM) phosphors were synthesized and were coated with SiO2. It was revealed that the surface coating of phosphors with SiO2 leads to an increase in luminance intensity of PDP devices. This seems to be due to the increase of the excitation light which is transmitted into the phosphor, i.e., an effective vacuum ultraviolet absorption of the phosphor via SiO2. The experimental results suggest that the surface coating of BAM with SiO2a is a way to improve the luminance of the PDP.

Telomere length changes in patients with aplastic anaemia.

To investigate telomere changes in patients with aplastic anaemia (AA) and clinical factors influencing the telomere dynamics, telomere length (TL) was measured in peripheral blood mononuclear cells using Southern blot analysis of 42 patients with AA and 39 healthy normal controls. Nineteen patients received supportive treatment only, while the remaining 23 patients received immunosuppressive therapy with anti‐thymocyte globulin or anti‐lymphocyte globulin ± cyclosporin A. In AA patients, TL was on average 1·41 kb shorter than that of age‐matched normal controls (P < 0·001). In patients treated with immunosuppression, the mean TL of non‐responders was significantly shorter than that of age‐matched normal controls (P < 0·001), while no difference in TL was detected in responders compared with controls. Positive correlation was observed between the extent of telomere shortening, the severity of neutropenia (P = 0·05) and the degree of mean corpuscular volume elevation (P = 0·005) at the time of the study. However, there was no correlation with time elapsed since diagnosis (P = 0·214). These findings suggest that haematopoietic stem cells in patients with AA rapidly lose TL at the onset of the disease. The TL shortening may reflect the severity of impairment of haematopoiesis.

Chronic myeloid leukemia patient manifesting fatal hepatitis B virus reactivation during treatment with imatinib rescued by liver transplantation: case report and literature review

Imatinib mesylate (imatinib) is now a standard treatment for patients with chronic myeloid leukemia (CML). Although imatinib is known to have a potential impact on various infectious organisms by altering the T-cell mediated immune response, only two cases of hepatitis B virus (HBV) reactivation during imatinib treatment have actually been reported. The role of liver transplantation (LT) after fatal HBV reactivation in patients with potentially treatable or curable hematologic malignancy is also unknown. Therefore, this report presents a case of fatal HBV reactivation during imatinib treatment for CML, where the patient is rescued by LT. Following a successful living donor LT, the liver function improves rapidly and the patient remains in complete cytogenetic remission after retreatment with imatinib for 6 months. The present report also covers the role of tyrosine kinase inhibitor in triggering HBV reactivation and a literature review of fulminant hepatic failure in CML patients taking imatinib.

Optical properties of neodymium-containing polymethylmethacrylate films for the organic light emitting diode color filter

In order to improve the primary color purity of the organic light emitting diode (OLED), neodymium(Nd)-containing polymethylmethacrylate (PMMA) films have been fabricated by a solvent casting method, and their optical properties have been investigated as functions of Nd content in films. The study has revealed that absorption in Nd-containing PMMA films is due to intratransition within the 4f shell of the Nd3+ ion, and that it becomes larger with an increase in the Nd concentration in films. In OLED devices with color filters, luminance from unnecessary emissive light is sufficiently reduced, resulting in a wider color gamut and higher color purity.

Electrical properties of plasma display panel with Mg1−xZnxO protecting thin films deposited by a radio frequency magnetron sputtering method

In order to improve the material properties of the protective layer for alternating current plasma display panels, a small amount of ZnO was added to the MgO protective layer. The electrical properties and the surface characteristics of the Mg1−xZnxO films, deposited by a radio frequency magnetron sputtering method, were investigated. As the concentration of ZnO increases, the crystallinity of Mg1−xZnxO thin films improves and the grain size becomes larger. The firing and the sustaining voltages of panels with the Mg1−xZnxO protective layers, when the concentration of ZnO was 0.5at.%, was reduced by 20V, compared with the conventional panels with the MgO protective layers. It was also found that the panels with Mg1−xZnxO protective layers show the higher discharge intensity as the ZnO content increases at the same applied voltages, compared with panels with the conventional MgO protective layers.

Optical properties of inorganic (SiO2)1−x(Nd2O3)x alloy films for the color filter of plasma display panel

In order to improve the primary color purity of the plasma display panel (PDP), inorganic (SiO2)1−x(Nd2O3)x alloy films have been fabricated by the rf-magnetron sputtering method, and their optical properties have been investigated as functions of Nd2O3 contents in films and thickness of films. The study has revealed that absorption in (SiO2)1−x(Nd2O3)x films is due to intratransition within the 4f shell of the Nd3+ ion, and that it becomes larger with increasing Nd3+ ion concentrations in films and film thickness. In the PDP devices with our band rejection color filters, luminances from neon gas discharge itself and sidebands of phosphors are sufficiently reduced, resulting in wider color gamut and higher color purity.

Effects of hydrogen doping on surface and discharge properties of MgO thin films grown by ion plating

Magnesium oxide (MgO) thin films with a high crystallinity and a preferred (1 1 1) orientation were prepared by an ion plating technique and the effects of hydrogen flow rates on their structural, surface, optical and discharge properties were investigated. Dependence on hydrogen flow rates has a quadratic curve type characteristic with an inflection point at a hydrogen flow rate of 60 sccm. The results indicated that the controlled grain shape and the size of MgO film grown under an optimal hydrogen doping condition affect the surface, microstructure and defect states in the MgO films, resulting in a reduction in the discharge delay time of ac plasma display panels significantly.

Clinical significance of autoantibody expression in allogeneic stem-cell recipients.

Background. The occurrence of autoantibodies has been reported in allogeneic stem-cell recipients, but the association of this occurrence with chronic graft-versus-host disease (cGVHD) or survival remains uncertain. Methods. A total of 121 consecutive patients who underwent allogeneic stem-cell transplantation from November 2001 to March 2008 and survived at least 3 months after transplantation were included in this study. Results. Forty-seven patients (38.8%) expressed at least one of various autoantibodies after transplantation. Antinuclear antibody was positive in 22 patients (18.2%), antidouble stranded DNA in seven (5.8%), antismooth muscle antibody in six (5%), rheumatoid factor in 17 (14.0%), and a positive Coombs test recorded for 12 patients (9.9%). cGVHD was more commonly diagnosed in the patients with autoantibody expression (61.7% vs. 43.2%, P=0.048). The patients expressing autoantibodies had a better 5-year overall survival than those without any autoantibody expression: 70.2% and 47.9% for the autoantibody-positive and autoantibody-negative patients, respectively (P=0.002). The cumulative incidence of relapse was 21.5% and 39.3% for the autoantibody-positive and autoantibody-negative patients, respectively (P=0.023). In particular, the patients expressing autoantibodies without cGVHD had a better overall survival (100%) than the patients in the other groups: 63.1% for the autoantibody- and cGVHD-positive patients, 59.6% for the autoantibody-negative and cGVHD-positive patients, and 36.6% for the autoantibody- and cGVHD-negative patients. The multivariate analysis identified autoantibody expression as a good prognostic factor regarding survival (hazard ratio=0.378, 95% confidence interval=0.185–0.775, P=0.008). Conclusion. The occurrence of autoantibodies after allogeneic stem-cell transplantation was found to be related to cGVHD, and patients expressing autoantibodies had a better survival.

Effects of the Plasma Treatment on the Electrical Properties of Indium Tin Oxide Thin Films

The sheet resistance of the ITO films after oxygen and nitrogen plasma treatments was investigated, based on the change in the lattice characteristics such as the grain size and the lattice strain. The plasma treatment yields an increase in the grain size thence the electrical conductivity in addition to better surface morphology. The decrease in lattice strain is attributable to the increase in the grain size. The experimental results imply that the grain boundary scattering limited mobility plays an important role in the conductivity of ITO films.

Degradation studies on high-voltage-driven organic light-emitting device using in situ on-operation method with scanning photoelectron microscopy

We investigated the degradation behavior of a high-voltage-driven organic light-emitting device (OLED) by operating the device in an ultrahigh-vacuum environment. In situ on-operation method provided the initial degradation process when the OLED was biased inside an analysis chamber. The degraded area was probed by scanning photoelectron microscopy (SPEM) using synchrotron. SPEM showed that the degradation was accompanied by a local drift of indium tin oxide (anode) toward Al (cathode) and that the heat from the degraded area separated the cathode from the Alq3 layer, forming large bubbles. These results also indicate that microbubbles were formed under the Alq3, implying, before popping, the existence of local high-temperature degradation spots.