Publications by authors named "Seung Jae Oh"

We used deep learning methods to develop an AI model capable of autonomously delineating cancerous regions in digital pathology images (H&E-stained images). By using a transgenic brain tumor model derived from the TS13-64 brain tumor cell line, we digitized a total of 187 H&E-stained images and annotated the cancerous regions in these images to compile a dataset. A deep learning approach was executed through DEEP:PHI, which abstracts Python coding complexities, thereby simplifying the execution of AI training protocols for users.

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We investigated an asymmetric slab grating structure to achieve significant tuning of the quality (Q) factor for a leaky mode while minimizing frequency variation. This structure comprises two identical gratings placed on the top and bottom of a slab waveguide, with one grating laterally shifted to introduce asymmetry. Simulations demonstrate that lateral shifting of one grating induces extensive changes in the Q-factor with minimal frequency variation, particularly near the band-flip filling fraction because the band-flip filling fraction remains unaffected by the shifting.

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Gastric cancer (GC) is recognized as the fifth most prevalent malignant tumor worldwide. It is characterized by diverse clinical symptoms, treatment responses, and prognoses. In GC prognosis, the promotion of epithelial-mesenchymal transition (EMT) fosters cancer cell invasion and metastasis, thereby triggering the dissemination of tumor cells.

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Terahertz (THz) electromagnetic waves, known for their unique response to water, offer promising opportunities for next-generation biomedical diagnostics and novel cancer therapy technologies. This study investigated the impedance-matching effect, which enhances the efficiency of THz wave delivery into tissues and compensates for the signal distortion induced by the refractive index mismatch between the target and the sample substrate. Three candidate biocompatible materials, water, glycerol, and petroleum jelly were applied to a skin phantom and compared using THz two-dimensional imaging and time-of-flight imaging methods.

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Article Synopsis
  • Terahertz (THz) waves, which range from 0.1 to 10 THz, have various applications like security, biomedical imaging, and material testing, but their low resolution is a challenge due to long wavelengths.
  • Researchers introduced J-Net, an enhanced U-Net architecture, to improve THz image resolution by efficiently mapping low-resolution features to high-resolution images.
  • J-Net outperformed other super-resolution techniques, achieving a peak signal-to-noise ratio (PSNR) of 32.52 dB and showing better visual quality in real THz images compared to existing methods.
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  • Birefringence is a key property of certain materials, allowing for advanced imaging techniques like polarized light microscopy, which traditionally requires complex setups.
  • A new lens-less microscopy method has been developed that captures complex and birefringence images without optical lenses or moving parts, using an optical mask and LED light.
  • This innovative technique has demonstrated impressive resolution and a wide field of view, successfully imaging various anisotropic samples, including biological tissues and crystals.
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Purpose: Advancements in photodynamic diagnosis (PDD) and photodynamic therapy (PDT) as a standard care in cancer therapy have been limited. This study is aimed to investigate the clinical availability of 5-aminolevulinic acid (5-ALA)-based PDD and PDT in glioblastoma (GBM) patient-derived tumorspheres (TSs) and mouse orthotopic xenograft model.

Methods: PDT was performed using a 635 nm light-emitting diode (LED).

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Article Synopsis
  • The study focused on changes in the spectral properties of anti-adhesion films made from polyethylene oxide (PEO), which were modified through electron beam irradiation and examined using terahertz time-domain spectroscopy (THz-TDS).
  • The findings indicated that the films' terahertz characteristics were influenced by porosity from the sample preparation processes, with evidence gathered from optical coherence tomography (OCT) imaging.
  • The research highlights the potential of THz-TDS as a non-invasive method for monitoring the cross-linking states in polymers, marking a novel approach in polymer inspection.
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Alzheimer's disease (AD), one of the leading senile disorders in the world, causes severe memory loss and cognitive impairment. To date, there is no clear cure for AD. However, early diagnosis and monitoring can help mitigate the effects of this disease.

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Metal thin films have been widely used as conductors in semiconductor devices for several decades. However, the resistivity of metal thin films such as Cu and TiN increases substantially (>1000%) as they become thinner (<10 nm) when using high-density integration to improve device performance. In this study, the resistivities of MAX-phase VAlC films grown on sapphire substrates exhibited a significantly weaker dependence on the film thickness than conventional metal films that resulted in a resistivity increase of only 30%, as the VAlC film thickness decreased from approximately 45 to 5 nm.

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A generic top-down approach for the preparation of extended arrays of high-aspect ratio GaAs nanowires (NWs) with different crystallographic orientations (i.e., [100] or [111]) and morphologies (i.

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Terahertz (THz) imaging technology has shown significant potential for use in biomedical imaging owing to its non-ionizing characteristics by its low photon energy and its ultrabroadband spectral comparability with many molecular vibrational resonances. However, despite the significant advantage of being able to identify bio-materials in label-free configurations, most meaningful signals are buried by huge water absorption, thus it is very difficult to distinguish them using the small differences in optical constants at THz regime, limiting the practical application of this technology. Here, we demonstrate advanced THz imaging with enhanced color contrast by the use of THz field that is localized and enhanced by a nanometer-scale slot array.

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Metabolic rewiring has been recognized as an important feature to the progression of cancer. However, the essential components and functions of lipid metabolic networks in breast cancer progression are not fully understood. In this study, we investigated the roles of altered lipid metabolism in the malignant phenotype of breast cancer.

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We have achieved heteroepitaxial stacking of a van der Waals ( vdW) monolayer metal, 1T'-WTe, and a semiconductor, 2H-WSe, in which a distinctively low contact barrier was established across a clean epitaxial vdW gap. Our epitaxial 1T'-WTe films were identified as a semimetal by low temperature transport and showed the robust breakdown current density of 5.0 × 10 A/cm.

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Background: Ginseng is believed to have antitumor activity. Autophagy is largely a prosurvival cellular process that is activated in response to cellular stressors, including cytotoxic chemotherapy; therefore, agents that inhibit autophagy can be used as chemosensitizers in cancer treatment. We examined the ability of Korean Red Ginseng extract (RGE) to prevent autophagic flux and to make hepatocellular carcinoma (HCC) cells become more sensitive to doxorubicin.

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We investigated the water contents in several organ tissues such as the liver, spleen, kidney, and brain tissue of rats using the terahertz spectroscopic imaging technique. The water contents of the tissues were determined by using a simple equation containing the absorption coefficients of fresh and lyophilized tissues and water. We compared the measured water contents with the difference in mass of tissues before and after lyophilization.

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Gastrointestinal (GI) tract metastasis of primary breast cancer is very rare. We present a patient with small bowel obstruction from distant metastasis of primary breast cancer. Each characteristic features of concern of GI tract distant metastasis from many pervious studies has been reported differently.

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Photodynamic therapy (PDT) is a treatment option for skin cancer and premalignant skin diseases and exhibits rejuvenation effects, including reducing fine wrinkles and whitening, on aged skin. In this study, we investigated the mechanism underlying the whitening effects of PDT on melanocytes (MCs) in vitro and in vivo. Exposure of MCs to PDT in vitro reduced their melanin content and tyrosinase activity without, however, affecting cell survival.

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We report improvement of terahertz (THz) wave radiation for Si-based catalyst-free InAs nanowires (NWs) by simple dipping into tap water (DTW). In addition, the possibility of using InAs NWs as a cost-effective method for biomedical applications is discussed by comparison to bulk InAs. The peak-to-peak current signals (PPCSs) of InAs NWs measured from THz time-domain spectroscopy increased with increasing NW height.

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Gross total resection (GTR) of glioma is critical for improving the survival rate of glioma patients. One of the greatest challenges for achieving GTR is the difficulty in discriminating low grade tumor or peritumor regions that have an intact blood brain barrier (BBB) from normal brain tissues and delineating glioma margins during surgery. Here we present a highly sensitive, label-free terahertz reflectometry imaging (TRI) that overcomes current key limitations for intraoperative detection of World Health Organization (WHO) grade II (low grade), and grade III and IV (high grade) gliomas.

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We designed and fabricated a novel terahertz (THz) otoscope to help physicians to diagnose otitis media (OM) with both THz diagnostics and conventional optical diagnostics. We verified the potential of this tool for diagnosing OM using mouse skin tissue and a human tympanic membrane samples prior to clinical application.

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Various tandem cell configurations have been reported for highly efficient and spontaneous hydrogen production from photoelectrochemical solar water splitting. However, there is a contradiction between two main requirements of a front photoelectrode in a tandem cell configuration, namely, high transparency and high photocurrent density. Here we demonstrate a simple yet highly effective method to overcome this contradiction by incorporating a hybrid conductive distributed Bragg reflector on the back side of the transparent conducting substrate for the front photoelectrochemical electrode, which functions as both an optical filter and a conductive counter-electrode of the rear dye-sensitized solar cell.

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We have investigated the feasibility of THz time-domain reflectometry for the discrimination of human early gastric cancer (EGC) from the normal gastric region. Eight fresh EGC tissues, which were resected by endoscopic submucosal dissection, were studied. Of them, six lesions were well discriminated on THz images and the regions well correlated with tumor regions on pathologically mapped images.

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We present an implementation of spectrally encoded slit confocal microscopy. The method employs a rapid wavelength-swept laser as the light source and illuminates a specimen with a line focus that scans through the specimen as the wavelength sweeps. The reflected light from the specimen is imaged with a stationary line scan camera, in which the finite pixel height serves as a slit aperture.

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We have investigated basic properties of normal gastrointestinal (GI) tract tissues, including glandular stomach (GS), fore stomach (FS), large intestine (LI), small intestine (SI), and esophagus (ESO), from a rat model using terahertz (THz) reflection imaging and spectroscopy. The THz images collected from stratified squamous epithelia (SSE) of FS and ESO show a lower peak-to-peak value compared to those from columnar epithelia (CE) of GS, LI, or SI because the SSE contains less water than CE. The refractive index and absorption coefficient of FS were less than those of GS or LI, both having values similar to those of water.

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