Seok Woo Yang

Enhanced electro-optical properties of Y2O3 (yttrium trioxide) nanoparticle-doped twisted nematic liquid crystal devices

We report the electro-optic (EO) characteristics of a Y2O3 nanoparticle-doped nematic liquid crystal (NLC) system. After doping with 2 wt.% Y2O3 nanoparticles, LC alignment shows a homogeneous orientation state without aggregation and crack. In particular, the pretilt angle was slightly increased in proportion to Y2O3 doping concentration. Response time was improved by nearly 53%, and the threshold voltage for display operation was reduced from 4.2 V to 2.6 V. We assumed that superior EO properties were achieved by the Y2O3 nanoparticle, which reduces the field-screening effect of impurity ions. We also confirmed that enhanced EO characteristics were achieved without loss of light transmittance.

Effects of the dispersion of zirconium dioxide nanoparticles on high performance electro-optic properties in liquid crystal devices

We explored the doping effects of zirconium dioxide (ZrO2) nanoparticles on the characteristics of liquid crystal (LC) devices. The electro-optic (EO) properties of LCs with various doping contents were changed. The addition of ZrO2 nanoparticles contributed to an improvement in EO properties in nematic LC cells such as low voltage operation and fast response time. The LC cells with 1.5 wt% ZrO2 nanoparticles showed the lowest threshold voltage (0.8 V) and the fastest response time (14.5 ms), and especially, a rise time of 0.7 ms, which can be applied for use in advanced LC devices.

Advanced gastric carcinoma with signet ring cell carcinoma versus non-signet ring cell carcinoma: differentiation with multidetector CT.

Objective: The purpose of this study is to assess the capability of multidetector computed tomography (MDCT) to assist in the differentiation of advanced gastric carcinoma with signet ring cell type from that with non-signet ring cell carcinoma (NSRC) with a focus on the thickened stomach wall itself. Methods: We retrospectively reviewed MDCT results in 80 patients with pathologically proven advanced gastric carcinoma with signet ring cell carcinoma (SRC) (n = 35) and NSRC (n = 45). MDCT images of 80 patients were analyzed retrospectively on gross appearance of thickened gastric wall (polypoid/fungating/ulcerative/diffuse infiltrative), predominantly thickened layer (inner/outer), contrast-enhancement pattern (nonlayered/layered) and degree of enhancement (high/moderate/low). Results: The most common type of gross appearance in both carcinomas was fungating, and the more common contrast-enhancement pattern in both carcinomas was a nonlayered pattern. The predominantly thickened layer was a high attenuation inner layer in both carcinomas. High-degree contrast enhancement was more common in SRC (37.1% of patients) than NSRC (15.6% of patients) with statistically significant difference (P = 0.01). Conclusions: Multidetector CT cannot distinguish SRC from NSRC based on the thickened stomach wall alone. But, high-degree contrast enhancement was more common in advanced gastric carcinoma with SRC than that with NSRC.

Oxidation state investigation concerning liquid crystal alignment on polydimethylsiloxane layer by ion beam irradiation

This is a study of ion beam (IB)-irradiated polydimethylsiloxane (PDMS) layer-induced liquid crystal (LC) effects and electro-optical (EO) properties with varying IB incident angles. Depending on the incident angle, the homogeneously aligned LC on the PDMS layer via IB irradiation was embodied with LC alignment capability and performance. Based on X-ray photoelectron spectroscopic (XPS) analysis, the intensity of O–Si as a function of incident angle shows oxidation of the IB-treated PDMS surface. It revealed that van der Waals forces generated by delocalised electrons on the PDMS surface were attributed to LC alignment by selective destructions of the Si–C bonding in the direction of IB irradiation. EO characteristics comparable with rubbed polyimide were also achieved.

MR Cholangiography of Accessory Bile Duct Connected to the Stomach

WEB This is a Web exclusive article. ccessory bile ducts, often draining a segment of the right lobe of the liver into the common bile duct or the gallbladder, have been found at as many as 4% of necropsies [1]. Accessory bile ducts connected to the gastrointestinal tract are extremely rare [1, 2]. Since the first report of double bile duct draining into the gastrointestinal tract as a congenital anomaly registered by Vesalius in 1543, more than 50 cases of double biliary drainage have been reported worldwide [2]. We describe a case of accessory bile duct that connected the caudate lobe of the liver to the stomach in which MR cholangiography (MRC) showed the biliary anomaly and provided sufficient evidence for development of an appropriate surgical plan. Subsequent intraoperative cholangiography supplemented the imaging diagnosis, and surgical resection was performed. To our knowledge, there have been no reported cases of MRC diagnosis of accessory bile duct connected to the gastrointestinal tract.

Homogeneously Aligned Liquid Crystals on a ZrO2 Alignment Film Using Ion-Beam Irradiation

This paper introduces the characteristics of the zirconium dioxide (ZrO2) inorganic film deposited by radio-frequency magnetron sputtering. The homogeneously aligned liquid crystal (LC) on ZrO2 layer via ion beam (IB) irradiation at various incident angles was embodied with LC alignment capability and performance. The x-ray photoelectron spectroscopic (XPS) data shows that O-Zr bonds on the ZrO2 surface are broken and induce the van der Waals force for the homogeneous alignment of LCs. That is the van der Waals force, affecting the alignment of the LCs, is verified by the contact angle of the liquid and by the XPS analysis on the ZrO2 thin film. In addition, the advantage of IB alignment method is verified by using atomic force microscope (AFM).

Do Helper T Cell Subtypes in Lymphocytic Thyroiditis Play a Role in the Antitumor Effect

Background Papillary thyroid carcinoma (PTC) is frequently accompanied by lymphocytic thyroiditis (LT). Some reports claim that Hashimoto’s thyroiditis (the clinical form of LT) enhances the likelihood of PTC; however, others suggest that LT has antitumor activity. This study was aimed to find out the relationship between the patterns of helper T cell (Th) cytokines in thyroid tissue of PTC with or without LT and the clinicopathological manifestation of PTC. Methods Fresh surgical samples of PTC with (13 cases) or without (10 cases) LT were used. The prognostic parameters (tumor size, extra-thyroidal extension of PTC, and lymph node metastasis) were analyzed. The mRNA levels of two subtypes of Th cytokines, Th1 (tumor necrosis factor α [TNF-α], interferon γ [IFN-γ ], and interleukin [IL] 2) and Th2 (IL-4 and IL-10), were analyzed. Because most PTC cases were microcarcinomas and recent cases without clinical follow-up, negative or faint p27 immunoreactivity was used as a surrogate marker for lymph node metastasis. Results PTC with LT cases showed significantly higher expression of TNF-α (p = .043), IFN-γ (p < .010), IL-4 (p = .015) than those without LT cases. Although the data were not statistically significant, all analyzed cytokines (except for IL-4) were highly expressed in the cases with higher expression of p27 surrogate marker. Conclusions These results indicate that mixed Th1 (TNF-α, IFN-γ , and IL-2) and Th2 (IL-10) immunity might play a role in the antitumor effect in terms of lymph node metastasis.

Extremely Well-Differentiated Papillary Thyroid Carcinoma Resembling Adenomatous Hyperplasia Can Metastasize to the Skull: A Case Report.

We describe herein histologic, immunohistochemical, and molecular findings and clinical manifestations of a rare case of an extremely well differentiated papillary thyroid carcinoma (EWD-PTC). Similarly, it is also difficult to diagnose follicular variant papillary thyroid carcinoma (FVPTC), whose diagnosis is still met with controversy. A recently reported entity of well-differentiated tumor of uncertain malignant potential (WDT-UMP) is added to the diagnostic spectrum harboring EWD-PTC and FVPTC. We report this case, because EWD-PTC is different from FVPTC in its papillary architecture, and also from WDT-UMP in its recurrence and metastatic pattern. These morphologically deceptive entities harbored diagnostic difficulties in the past because the diagnosis depended solely on histology. However, they are now diagnosed with more certainty by virtue of immunohistochemical and molecular studies. We experienced a case of EWD-PTC, which had been diagnosed as adenomatous hyperplasia 20 years ago and manifested recurrence with lymph node (LN) metastasis 7 years later. After another 7 years of follow-up, a new thyroid lesion had developed, diagnosed as FVPTC, with LN metastasis of EWD-PTC. One year later, the patient developed metastatic FVPTC in the skull. Immunohistochemically, the EWD-PTC was focally positive for CK19, negative for galectin-3, and focally negative for CD56. Molecular studies revealed BRAF-positivity and K-RAS negativity. The FVPTC in the left thyroid showed both BRAF and K-RAS negativity. In conclusion, EWD-PTC and FVPTC share similar histologic features, but they are different tumors with different molecular biologic and clinical manifestations. A large cohort of EWD-PTC should be included in further study.

Etching Effects of Blended Polyimide Layers for Liquid Crystals

This paper introduces a novel alignment method for control of pretilt angles in liquid crystals (LCs) using an etchant dipping effect on a mixed polyimide layer as an alternative alignment layer for liquid crystal display applications. A rubbing process was used to induce LC alignment and induce the measured LC pretilt angle on the etchant dipped mixture layer. The resulting thermal stabilities were good, however thermal stresses decreased as the etchant dipping time increased, indicating that the LC anchoring energy became weaker as a function of etchant dipping time after treatment. Excellent voltage-transmittance characteristics for vertically aligned cells were observed for all conditions.