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2,261 result(s) for "Kim, Sang Cheol"
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Single- and double-walled boron nitride nanotubes: controlled synthesis and application for water purification
Research interest in boron nitride nanotubes (BNNTs) has increased after the recent success of large-scale BNNT syntheses using high-temperature-pressure laser ablation or high-temperature plasma methods. Nonetheless, there are limits to the application and commercialization of these materials because of the difficulties associated with their fine structural control. Herein, the growth kinetics of BNNTs were systemically studied for this purpose. The growth pressure of the nitrogen feed gas was varied while the growth temperature remained constant, which was confirmed by black body radiation measurements and calculations based on a heat loss model. Changing from the diffusion-limited regime to the supply-limited regime of growth kinetics based on the optimized BNNT synthesis condition afforded the control of the number of BNNT walls. The total amount of BNNTs possessing single and double walls was over 70%, and the BNNT surface area increased to 278.2 m2/g corresponding to small wall numbers and diameters. Taking advantage of the large surface area and high-temperature durability of the material, BNNTs utilized as a recyclable adsorbent for water purification. The efficiency of the BNNTs for capturing methylene blue particles in water was approximately 94%, even after three repetition cycles, showing the potential of the material for application in the filter industry.
Polydopamine-based Implantable Multifunctional Nanocarpet for Highly Efficient Photothermal-chemo Therapy
We report a design and fabricate multifunctional localized platform for cancer therapy. Multiple stimuli-responsive polydopamine (PDA) was used for surface modification of electrospun doxorubicin hydrochloride (DOX) loaded polycaprolactone (PCL) fibers to make a designated platform. Photothermal properties such as photothermal performance and stability of the resulting composite mats were studied under the irradiation of the near-infrared (NIR) laser of 808 nm. With the incorporation of PDA into the fiber, a remarkable increase of local temperature was recorded under NIR illumination in a concentration-dependent manner with excellent stability. Drug released assay results revealed PDA coated PCL-DOX mats showed pH and NIR dual responsive behavior thereby exhibiting improved drug release in an acidic medium compared to physiological pH condition (pH 7.4) which is further increased by NIR exposure. The cancer activity in vitro of the mats was evaluated using cell counting (CCK) and live and dead cell assays. The combined effect of NIR mediated hyperthermia and chemo release resulting improved cells death has been reported. In summary, this study presents a major step forward towards a therapeutic model to cancer treatment utilizing pH and NIR dual responsive property from PDA alone in a fibrous mat.
GALNT14 promotes lung-specific breast cancer metastasis by modulating self-renewal and interaction with the lung microenvironment
Some polypeptide N-acetyl-galactosaminyltransferases (GALNTs) are associated with cancer, but their function in organ-specific metastasis remains unclear. Here, we report that GALNT14 promotes breast cancer metastasis to the lung by enhancing the initiation of metastatic colonies as well as their subsequent growth into overt metastases. Our results suggest that GALNT14 augments the self-renewal properties of breast cancer cells (BCCs). Furthermore, GALNT14 overcomes the inhibitory effect of lung-derived bone morphogenetic proteins (BMPs) on self-renewal and therefore facilitates metastasis initiation within the lung microenvironment. In addition, GALNT14 supports continuous growth of BCCs in the lung by not only inducing macrophage infiltration but also exploiting macrophage-derived fibroblast growth factors (FGFs). Finally, we identify KRAS-PI3K-c-JUN signalling as an upstream pathway that accounts for the elevated expression of GALNT14 in lung-metastatic BCCs. Collectively, our findings uncover an unprecedented role for GALNT14 in the pulmonary metastasis of breast cancer and elucidate the underlying molecular mechanisms. Polypeptide N-acetyl-galactosaminyltransferases (GALNTs) are associated with cancer, but their function in organ-specific metastasis is unclear. Here the authors show that GALNT14 promotes breast cancer metastasis to the lung by enhancing the initiation of metastatic colonies and subsequent growth.
Strategic design of a Mussel-inspired in situ reduced Ag/Au-Nanoparticle Coated Magnesium Alloy for enhanced viability, antibacterial property and decelerated corrosion rates for degradable implant Applications
Magnesium (Mg) and its alloys have attracted much attention as a promising candidate for degradable implant applications however the rapid corrosion of magnesium inside the human body greatly limits its use as an implant material. Therefore, coating the alloy surface with a multifunctional film is a promising way to overcome the drawbacks. Here we propose for the first time a multifunction layer coating to enhance the cell viability, antibacterial property and decelerated corrosion rates to act as a novel material to be used for degradable implant Applications. For that, the magnesium alloy (AZ31) was first treated with hydrofluoric acid (HF) and then dopamine tris Hydrochloric acid (tris-HCL) solution. The reducing catechol groups in the polydopamine (PD) layer subsequently immobilize silver/gold ions in situ to form uniformly dispersed Ag/Au nanoparticles on the coating layer. The successful formation of Ag/Au nanoparticles on the HF-PD AZ31 alloy was confirmed using XPS and XRD, and the morphology of all the coated samples were investigated using SEM images. The alloy with HF-PDA exhibit enhanced cell attachment and proliferation. Moreover, the nanoparticle immobilized HF-PD alloy exhibited dramatic corrosion resistance enhancement with superior antibacterial properties and accountable biocompatibility. Thus the result suggest that HF-PD Ag/Au alloy has great potential in the application of degradable implant and the surface modification method is of great significance to determine its properties.
The Anticancer Effect of Fucoidan in PC-3 Prostate Cancer Cells
Fucoidan, a sulfated polysaccharide, has a variety of biological activities, such as anti-cancer, anti-angiogenic and anti-inflammatory. However, the mechanisms of action of fucoidan as an anti-cancer agent have not been fully elucidated. The present study examined the anti-cancer effect of fucoidan obtained from Undaria pinnatifida in PC-3 cells, human prostate cancer cells. Fucoidan induced the apoptosis of PC-3 cells by activating both intrinsic and extrinsic pathways. The induction of apoptosis was accompanied by the activation of extracellular signal-regulated kinase mitogen-activated protein kinase (ERK1/2 MAPK) and the inactivation of p38 MAPK and phosphatidylinositol 3-kinase (PI3K)/Akt. In addition, fucoidan also induced the up-regulation of p21Cip1/Waf and down-regulation of E2F-1 cell-cycle-related proteins. Furthermore, in the Wnt/β-catenin pathway, fucoidan activated GSK-3β that resulted in the decrease of β-catenin level, followed by the decrease of c-myc and cyclin D1 expressions, target genes of β-catenin in PC-3 cells. These results suggested that fucoidan treatment could induce intrinsic and extrinsic apoptosis pathways via the activation of ERK1/2 MAPK, the inactivation of p38 MAPK and PI3K/Akt signaling pathway, and the down-regulation of Wnt/β-catenin signaling pathway in PC-3 prostate cancer cells. These data support that fucoidan might have potential for the treatment of prostate cancer.
A Robust Deep-Learning-Based Detector for Real-Time Tomato Plant Diseases and Pests Recognition
Plant Diseases and Pests are a major challenge in the agriculture sector. An accurate and a faster detection of diseases and pests in plants could help to develop an early treatment technique while substantially reducing economic losses. Recent developments in Deep Neural Networks have allowed researchers to drastically improve the accuracy of object detection and recognition systems. In this paper, we present a deep-learning-based approach to detect diseases and pests in tomato plants using images captured in-place by camera devices with various resolutions. Our goal is to find the more suitable deep-learning architecture for our task. Therefore, we consider three main families of detectors: Faster Region-based Convolutional Neural Network (Faster R-CNN), Region-based Fully Convolutional Network (R-FCN), and Single Shot Multibox Detector (SSD), which for the purpose of this work are called \"deep learning meta-architectures\". We combine each of these meta-architectures with \"deep feature extractors\" such as VGG net and Residual Network (ResNet). We demonstrate the performance of deep meta-architectures and feature extractors, and additionally propose a method for local and global class annotation and data augmentation to increase the accuracy and reduce the number of false positives during training. We train and test our systems end-to-end on our large Tomato Diseases and Pests Dataset, which contains challenging images with diseases and pests, including several inter- and extra-class variations, such as infection status and location in the plant. Experimental results show that our proposed system can effectively recognize nine different types of diseases and pests, with the ability to deal with complex scenarios from a plant's surrounding area.
Emission Characteristics and Control Device Effectiveness of Particulate Matters and Particulate-phase PAHs from Urban Charbroiling Restaurants: A Field Test
Urban restaurants that charbroil meat are a major emission source of fine particulate matter (PM) and polyaromatic hydrocarbons (PAHs) and receive frequent public complaints in large Korean cities. This study evaluated the effectiveness of newly installed pollution control equipment, including electrostatic precipitators (ESPs) and filters, at five charbroiling restaurants in different metropolitan areas near Seoul. The PM in the exhaust gas, which was sampled from the inflow and the outflow of the control devices, was measured with a 3-stage cascade impactor. The particle-bound PAHs, following pre-treatment, extraction, and concentration, were then quantitatively analyzed using high-resolution gas chromatography-mass spectrometry (GC-MS). According to our field tests, the flue gas emitted by these five restaurants contained average PM 10 , PM 2.5 , and PAH concentrations of 22.6 mg m –3 , 22.1 mg m –3 , and 4,127.1 ng m –3 , respectively. In addition, the ratio of the PM 2.5 to the PM 10 was 0.98, and the correlation coefficient between the PM 10 and the particulate-phase PAHs was 0.95, suggesting a close relationship between the fine particle fraction and PAHs. The air pollution control equipment demonstrated an overall removal efficiency above 90%, but specific cases exhibited an unexpectedly low efficiency (30%), indicating the necessity of periodic cleaning and consistent maintenance.
Clinical and genomic landscape of gastric cancer with a mesenchymal phenotype
Gastric cancer is a heterogeneous cancer, making treatment responses difficult to predict. Here we show that we identify two distinct molecular subtypes, mesenchymal phenotype (MP) and epithelial phenotype (EP), by analyzing genomic and proteomic data. Molecularly, MP subtype tumors show high genomic integrity characterized by low mutation rates and microsatellite stability, whereas EP subtype tumors show low genomic integrity. Clinically, the MP subtype is associated with markedly poor survival and resistance to standard chemotherapy, whereas the EP subtype is associated with better survival rates and sensitivity to chemotherapy. Integrative analysis shows that signaling pathways driving epithelial-to-mesenchymal transition and insulin-like growth factor 1 (IGF1)/IGF1 receptor (IGF1R) pathway are highly activated in MP subtype tumors. Importantly, MP subtype cancer cells are more sensitive to inhibition of IGF1/IGF1R pathway than EP subtype. Detailed characterization of these two subtypes could identify novel therapeutic targets and useful biomarkers for prognosis and therapy response. The prognosis and treatment of gastric cancer is complicated by heterogeneity. Here, the authors reveal two molecular subtypes, the mesenchymal subtype associated with poor survival and chemoresistance, and the epithelial phenotype associated with better survival and sensitivity to chemotherapy.
Data-driven electrolyte design for lithium metal anodes
Improving Coulombic efficiency (CE) is key to the adoption of high energy density lithium metal batteries. Liquid electrolyte engineering has emerged as a promising strategy for improving the CE of lithium metal batteries, but its complexity renders the performance prediction and design of electrolytes challenging. Here, we develop machine learning (ML) models that assist and accelerate the design of high-performance electrolytes. Using the elemental composition of electrolytes as the features of our models, we apply linear regression, random forest, and bagging models to identify the critical features for predicting CE. Our models reveal that a reduction in the solvent oxygen content is critical for superior CE. We use the ML models to design electrolyte formulations with fluorine-free solvents that achieve a high CE of 99.70%. This work highlights the promise of data-driven approaches that can accelerate the design of high-performance electrolytes for lithium metal batteries.
Short duration cancer treatment: inspired by a fast bio-resorbable smart nano-fiber device containing NIR lethal polydopamine nanospheres for effective chemo-photothermal cancer therapy
The objective of this study was to evaluate the efficacy of a combination of Photothermal therapy (PTT) and chemotherapy in a single nano-fiber platform containing lethal polydopamine nanopheres (PD NPs) for annihilation of CT 26 cancer cells. Polydioxanone (PDO) nanofiber containing PD and bortezomib (BTZ) was fabricated via electrospinning method. The content of BTZ and PD after optimization was 7% and 2.5% respectively with respect to PDO weight. PD NPs have absorption band in near-infrared (NIR) with resultant rapid heating capable of inducing cancer cell death. The samples was divided into three groups - PDO, PDO+PD, and PDO+PD-BTZ for analysis. In combined treatment, PDO nanofiber alone could not inhibit cancer cell growth as it neither contain PD or BTZ. However, PDO+PD fiber showed a cell viability of approximately 20% after 72 hr of treatment indicating minimal killing via hyperthermia. In the case of PDO composite fiber containing BTZ, the effect of NIR irradiation reduced the viability of cancer cells down to around 5% after 72 h showing the efficiency of combination therapy on cancer cells elimination. However, due to higher photothermal conversion that may negatively affect normal cells above 46°C, we have employed 1 s \"OFF\" and 2 s \"ON\" after initial 9 s continuous irradiation to maintain the temperature between 42 and 46°C over 3 mins of treatment using 2 W/cm ; 808 nm laser which resulted to similar cell death. In this study, combination of PTT and chemotherapy treatment on CT 26 colon cancer cells within 3 min resulted in effective cell death in contrast to single treatment of either PTT and chemotherapy alone. Our results suggest that this nanofiber device with efficient heating and remote control drug delivery system can be useful and convenient in the future clinical application for localized cancer therapy.