• Research Paper

    Metal-Organic Framework Shell Encapsulation for pH-Responsive Protection of Yeast Cells
    Mi Jin Park, Sang Yeong Han, Sang Eun Hong, Woon Jung Kim, Kuk Ro Yoon
    Encapsulating living cells within porous crystalline materials has emerged as a powerful strategy for improving cellular stability in chemically or physically harsh … + READ MORE
    Encapsulating living cells within porous crystalline materials has emerged as a powerful strategy for improving cellular stability in chemically or physically harsh conditions. In this study, individual yeast cells were encapsulated with a zeolitic imidazolate framework-8 (ZIF-8) crystals via a biomimetic self-assembly process. Morphological analysis using electron microscopy confirmed the successful formation of a uniform and continuous protective shell around each cell. To evaluate the cytoprotective effect of the ZIF-8 coating, the encapsulated yeast cells were exposed to a range of pH conditions (pH 2~12). Fluorescence microscopy using fluorescein diacetate (FDA) staining revealed that over 50 % of the ZIF-8 encapsulated cells remained viable in alkaline environments (pH 8, 10, and 12), whereas non-encapsulated yeast cells showed 0 % viability across all tested conditions. The enhanced survival in alkaline media was attributed to the stability of the crystalline ZIF-8 shell, which remained partially intact and provided structural protection. In contrast, acidic conditions degraded the ZIF-8 shell, leading to cell membrane rupture and loss of viability. These findings demonstrate that ZIF-8 encapsulation can significantly improve the chemical resilience and survival of living yeast cells. This strategy holds great promise for applications in long-term cell preservation, transport, and pH-responsive biotechnological systems. - COLLAPSE
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    27 October 2025

  • Research Paper

    Effect of Cl2 Gas Exposure on the Surface Properties of Electropolished STS316L
    Donhee Lee, Du Hong Kang, Poongyeon Kim, Deokhyun Han, Man-Sik Kong, Si Young Chang
    In this study, the surface characteristics—including roughness, oxide layer thickness, and composition—of the electropolished layer on STS316L steel tubes subjected to double … + READ MORE
    In this study, the surface characteristics—including roughness, oxide layer thickness, and composition—of the electropolished layer on STS316L steel tubes subjected to double melting via the VIM/VAR process were investigated after exposure to Cl2 gas. The tubes were exposed to Cl2 gas for 1 to 13 d to simulate semiconductor conditions. Surface roughness increased with Cl2 exposure time, showing values of 0.01, 0.04, 0.04 and 0.03 µm after 0, 1, 5 and 9 d, respectively. At the same time, the oxide layer thickness on EPed STS316L, which was initially 8.2 nm, decreased to 3.18, 2.58 after 1, 5 d of Cl2 exposure, approaching the initial thickness of 2.38 nm observed on non-EPed STS316L. After 9 d, the thickness further decreased to 0.51 nm, with no significant change was observed thereafter. Before Cl2 exposure, the CrO/FeO ratio was 2.26. After 1, 5, and 9 d of exposure, the ratio decreased to 2.06, 1.75, and 1.27, respectively. In addition, the penetration depth of Cl into the oxide layer increased with longer exposure time. These results suggest that the formation of chromium chlorides led to the breakdown of the stable Cr2O3 layer. - COLLAPSE
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    27 October 2025

  • Research Paper

    Effect of Ammonia Concentration during Coprecipitation Reaction on the Multi-Component Hydroxide Precursors and Cathode Materials
    Dong Myung Kim, Ju Yeong Lee, Gyu-Seok Choi, Chunjoong Kim
    High nickel content Li(NixCoyMn1-x-y)O2 (NCM, x ≥ 0.9) cathode materials suffer from rapid capacity fading, … + READ MORE
    High nickel content Li(NixCoyMn1-x-y)O2 (NCM, x ≥ 0.9) cathode materials suffer from rapid capacity fading, a significant obstacle to their commercial application. To mitigate this issue, strategies such as doping and coating with various elements have been widely reported. In particular, multi-element doping has been explored as a potentially more effective alternative to single or dual element modification. Concurrently, the synthesis of high-entropy precursors via coprecipitation has gained significant attention. In this study, high nickel content precursors with nine components were synthesized by hydroxide coprecipitation under varying concentrations of ammonia that was employed as a chelating agent. The primary particle morphology of the precursors was found to be dependent on the ammonia concentration, which in turn influenced the physicochemical and electrochemical properties of the final cathode materials. At low ammonia concentration, the formation of secondary phases was detected. Notably, the cathode synthesized under high ammonia concentration exhibited excellent cycling stability, delivering a discharge capacity of 164.22 mAh/g after 100 cycles at 1 C, which corresponds to a capacity retention of approximately 91 % of its initial discharge capacity (180.50 mAh/g at 0.1 C). - COLLAPSE
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    27 October 2025

  • Research Paper

    Design of High-Strength High-Entropy Alloys Using a Variational Autoencoder-Based Inverse Design

    VAE 기반 소재 역설계를 이용한 고강도 고엔트로피 합금 설계

    Min-Gyu Kim, Chunghee Nam

    김민규, 남충희

    High-entropy alloys (HEAs) are alloys that contain multiple principal elements, each in the range of 5–35%. HEAs exhibit excellent properties, however, even … + READ MORE
    High-entropy alloys (HEAs) are alloys that contain multiple principal elements, each in the range of 5–35%. HEAs exhibit excellent properties, however, even with conventional trial-and-error, high-throughput experimentation, and computational materials approaches, exploring their vast compositional space remains highly challenging. Accordingly, data-driven machine learning and generative-model-based inverse design methods are increasingly essential. In this study, we propose a generative-model-enabled HEA inverse design framework aimed at improving ultimate tensile strength (UTS). We first compiled 501 HEA data points from published literature and performed statistical analyses to understand their characteristics. Next, we tuned the hyperparameters of XGBoost and random forest (RF) models via Bayesian optimization, compared their performance with that of a deep neural network (DNN), and selected XGBoost as the optimal predictive model. In the subsequent stage, we trained a PyTorch-based variational autoencoder (VAE) on data from regions of the latent space associated with high-UTS probability. We randomly sampled 1,000 latent vectors, decoded them to generate candidate alloy compositions, and evaluated these candidates using the optimized XGB model. Finally, Shapley additive explanations (SHAP) interpretability analysis and a network plot were used to quantify the contributions and interactions of each feature variable, thereby assessing the physical plausibility of the model-suggested compositions. - COLLAPSE
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    27 October 2025

  • Research Paper

    Driving Force Model of Plausibility Factors Influencing the Formation of Secondary Phases at the Metal/Glass Interface

    금속/유리 계면에서의 2차상 형성에 영향을 미치는 가성성 인자 구동력 모델

    Jin-Sam Choi

    최진삼

    The plausibility factors influencing heterogeneous nucleation at the metal/glass interface were systematically investigated as a function of temperature. Secondary phase formation at … + READ MORE
    The plausibility factors influencing heterogeneous nucleation at the metal/glass interface were systematically investigated as a function of temperature. Secondary phase formation at the metal/glass interface is governed by the contact angle, which is affected by volumetric changes, microstructural evolution driven by metal ion diffusion, and redox reactions influenced by the arrangement of oxygen layers on the metal surface. A comprehensive model was developed to describe these plausibility factors based on observed interfacial phenomena. Despite the inherent non-uniformity in ion distribution within the glass, the interfacial diffusion coefficient, derived from an Arrhenius plot, exhibited a clear temperature dependence, reflecting thermally activated diffusion processes. Above the glass transition temperature (Tg), chemical interactions between diffusing metal ions and migrating glass constituents were identified as the main driving force for secondary phase formation at the metal/glass interface. These chemical reactions not only alter the local stoichiometry but also contribute to structural rearrangements at the interface. The results highlight the complex interplay between the thermal, chemical, and structural factors that control nucleation at the metal/glass boundary. The proposed model provides valuable insight into the mechanisms of interfacial phase formation and offers a useful framework for the design and processing of metal/glass composite systems with tailored properties. - COLLAPSE
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    27 October 2025

  • Research Paper

    Effect of E-Glass Powder Addition on Characteristics of Blast Furnace Slag-Based Glass Marbles

    E-Glass 분말 첨가가 고로슬래그 기반 유리제조에 미치는 영향

    JI-Sun Lee, JuEun Park, Seunguk Song, Soon-il Kwon, Jinho Kim

    이지선, 박주은, 송승욱, 권순일, 김진호

    This study investigates the vitrification of blast furnace slag (BFS) by adjusting the content of steel slag and the added amount of … + READ MORE
    This study investigates the vitrification of blast furnace slag (BFS) by adjusting the content of steel slag and the added amount of E-glass. SaEb glasses were prepared with a composition of x wt% BFS and (100-x) wt% E-glass (x = 10, 20, 30, 40, and 50). Each composition was melted in a platinum crucible under atmospheric conditions at 1,500 °C for 2 h, and transparent glasses with a transmittance exceeding 75 % were fabricated. All SaEb glasses exhibit an amorphous pattern, indicating successful vitrification. We also analyzed their optical, thermal, and physical properties, including Fourier transform infrared spectroscopy (FT-IR), glass transition temperature (Tg), and x-ray pattern. As the E-glass content increased, the glass transition temperature of blast furnace slag-based glass decreased from 765 °C to 734 °C due to the weakening of the SiO4 unit structure. In all compositions, the glass transition–crystallization temperature difference exceeded 220 °C, confirming the glasses stability for slag fiber applications. The blast furnace slag-based glass exhibits potential for application in slag fiber production, and is expected to provide fundamental data for future studies on related materials. - COLLAPSE
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    27 October 2025
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Journal Informaiton Korean Journal of Materials Research Korean Journal of Materials Research
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