Zinc tin oxide (ZTO) thin films were deposited using atomic layer deposition (ALD) to ensure precise thickness control and uniformity. However, the low-temperature processing of ZTO often results in increased defect states, leading to degraded electrical performance. To address this issue, metal capping layers (Al or Au) were added to the ZTO active layer. The capping layers modulate electron energy levels at the interface, increase carrier density, and reduce interface traps, thereby improving electrical properties. Aluminum (Al) and gold (Au) were evaluated for their impact on key performance metrics, including electron mobility (μsat), threshold voltage (VT), subthreshold swing (SS), and on/off current ratio (ION/OFF). Results show that Al-capped ZTO thin-film transistors (TFTs) exhibited enhanced performance due to the lower work function of Al (4.0 eV), which facilitates electron injection and reduces contact resistance. In contrast, Au-capped ZTO TFTs showed decreased performance due to electron depletion caused by the higher work function of Au (5.1 eV). Optical analyses, including UPS and UV-Vis, revealed the band structure and work function of the ZTO thin films. This study concludes that the choice of capping material and its design parameters play a critical role in optimizing TFT performance, offering valuable insights for the development of next-generation high performance TFT devices.

본 연구는 기능성 화장품 소재 개발을 목표로 효모 유래 MPC의 세포 생리활성을 조사하였 다. 피부 세포주에 처리된 Cu와 Zn 이온 모두 세포 독성이 확인되었지만, 정제된 MPC는 결합된 금속 이온의 세포 독성을 획기적으로 제거하였다. 게다가 특정 농도의 MPC는 대조군과 비교하여 세포 생존 율을 오히려 약 20% 증가시켰다. MPC 중 효모 펩타이드-Cu(YP-Cu)는 UVB 자극으로 유도되는 세포 내 활성산소의 양을 약 30% 정도 유의하게 감소시켰지만, YP-Zn은 영향을 미치지 못했다. 또한, YP-Cu 처리는 피부 세포에서 콜라겐 유전자의 발현량을 2배 증가시켰고, 프로콜라겐 분비량은 1.7배 증 가시켰으며, UVB 자극에 의한 콜라겐 유전자의 발현 저해에도 효과적으로 대응했다. 결론적으로, 유리 금속 이온 자체는 세포독성 효과로 인해 화장품 소재에 적합하지 않지만, 정제된 MPC, 특히 YP-Cu는 이러한 금속 이온의 독성을 효과적으로 상쇄하고 세포 생존율을 향상시킬 뿐만 아니라, UVB 자극에 따 른 유해 효과를 완화하기 때문에 잠재적 기능성 화장품 소재로 사용될 수 있다.

The transportation of spent nuclear fuel between management stages is expected, and the transportation workers may be exposed to radiation. When transporting spent nuclear fuel, the ALARA principle must be observed for the workers. The objective of this study is to assess a radiation dose for workers transporting spent nuclear fuel using metal overpacks. For this objective, the cask to be handled was selected and the radiation source term was set. Then, the radiation exposure scenario for the transportation workers was defined. Finally, the dose rates for each location of operation were assessed using Monte Carlo simulations, and collective doses were derived for each operation considering the radiation exposure scenario. Each worker performed 11 operations to transport spent nuclear fuel to other facilities and was exposed to a total of 1.138 man-mSv. The operation of removing the bottom shield ring resulted in the highest radiation exposure at 0.503 man-mSv. In contrast, the operation of installing the impact limiter resulted in the lowest radiation exposure at 0.0009 man-mSv. The results of this study can be used to strengthen radiation protection measures for workers transporting spent nuclear fuel in dry storage facilities using metal overpacks.

Crystalline heptazine carbon nitride (HCN) is an ideal photocatalyst for photocatalytic ammonia synthesis. However, the limited response to visible light has hindered its further development. As a noble metal, Au nanoparticles (NPs) can enhance the light absorption capability of photocatalysts by the surface plasmon resonance (SPR) effect. Therefore, a series of Au NPs-loaded crystalline carbon nitride materials (AH) were prepared for photocatalytic nitrogen fixation. The results showed that the AH displayed significantly improved light absorption and decreased recombination rate of photo-generated carriers owing to the introduction of Au NPs. The optimal 2AH (loaded with 2 wt% Au) sample demonstrated the best photocatalytic performance for ammonia production with a yield of 70.3 μmol g− 1 h− 1, which outperformed that of HCN. This can be attributed to the SPR effect of Au NPs and alkali metal of HCN structure. These findings provide a theoretical basis for studying noble metal-enhanced photocatalytic activity for nitrogen fixation and offer new insights into advances in efficient photocatalysts.

In recent years, the search on fabrication of highly efficient, stable, and cost-effective alternative to Pt for the hydrogen evolution reaction (HER) has led to the development of new catalysts. In this study, we investigated the electrocatalytic HER activity of the Toray carbon substrate by creating defect sites in its graphitic layer through ultrasonication and anodization process. A series of Toray carbon substrates with active sites are prepared by modifying its surface through ultrasonication, anodization, and ultrasonication followed by anodization procedures at different time periods. The anodization process significantly enhances the surface wettability, consequently resulting in a substantial increase in proton flux at the reaction sites. As an implication, the overpotential for HER is notably reduced for the Toray carbon (TC-3U-10A), subjected to 3 min of ultrasonification followed by 10 min of anodization, which exhibits a significantly lower Tafel slope value of 60 mV/dec. Furthermore, the reactivity of the anodized surface for HER is significantly elevated, especially at higher concentrations of sulfuric acid, owing to the enhanced wettability of the substrate. The lowest Tafel slope value recorded in this study stands at 60 mV/dec underscoring the substantial improvements achieved in catalytic efficiency of the defect-rich carbon materials. These findings hold promise for the advancement of electrocatalytic applications of carbon materials and may have significant implications for various technological and industrial processes.

Carbon quantum dots (CQDs) are novel nanocarbon materials and widely used nanoparticles. They have gradually gained popularity in various fields due to their abundance, inexpensive cost, small size, ease of engineering, and distinct properties. To determine the antibacterial activity of metal-doped CQDs (metal-CQDs) containing Fe, Zn, Mn, Ni, and Co, we chose Staphylococcus aureus as a representative Gram-positive strain and Escherichia coli as a representative Gram-negative bacterial strain. Paper disc diffusion tests were conducted for the qualitative results, and a cell growth curve was drawn for quantitative results. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and IC50 were measured from cell growth curves. As a result, all of the metal-CQDs showed toxicity against both Gram-positive and Gram-negative bacteria. Furthermore, Gram-negative bacteria was vulnerable to metal-CQDs than Gram-positive bacteria. The toxicity differed concerning the type of metal-CQDs; Mn-CQDs exhibited the highest efficacy. Hence, this study suggested that CQDs can be used as new nanoparticles for antibiotics.

Graphene has been extensively investigated as a host material for Li metal anodes owing to its light weight, high electrical conductivity, high surface area, and exceptional mechanical rigidity. Many studies have focused on assembling twodimensional (2D) graphene sheets into three-dimensional (3D) forms, such as lamination, spheres, and carbon nanotubes; however, little attention has been paid to the technology of modifying 2D graphene sheets. Herein, nanoperforated graphene (NPG) was fabricated through a relatively straightforward process employing metal oxide catalysts based on aqueous solutions. Nanoperforations exhibited a size of approximately 5 nm and were introduced on the graphene sheet and lithiophilic carbonyl groups (C = O) at the edges, facilitating the rapid diffusion of Li+ and lowering the Li nucleation overpotential. In comparison to the reduced graphene oxide (RGO) host, the NPG host exhibited a lower lithium nucleation overpotential and a stable overpotential of ~ 30 mV for over 150 cycles as a stable host structure as a Li metal anode for Li metal batteries.

Mesocrystals are macroscopic structures formed by the assembly of nanoparticles that possess distinct surface structures and collective properties when compared to traditional crystalline materials. Various growth mechanisms and their unique features have promise as material design tools for diverse potential applications. This paper presents a straightforward method for metal–organic coordination-based mesocrystals using nickel ions and terephthalic acid. The coordinative compound between Ni2+ and terephthalic acid drives the particle-mediated growth mechanism, resulting in the mesocrystal formation through a mesoscale assembly. Subsequent carbonization converts mesocrystals to multidirectional interconnected graphite nanospheres along the macroscopic framework while preserving the original structure of the Ni-terephthalic acid mesocrystal. Comprehensive investigations demonstrate that multi-oriented edge sites and high crystallinity with larger interlayer spacing facilitate lithium ion transport and continuous intercalation. The resulting graphitic superparticle electrodes show superior rate capability (128.6 mAh g− 1 at 5 A g− 1) and stable cycle stability (0.052% of capacity decay per cycle), certifying it as an advanced anode material for lithium-ion batteries.

Pyrochemical processing and molten-salt reactors have recently garnered significant attention as they are promising options for future nuclear technologies, such as those for recycling spent nuclear fuels and the next generation of nuclear reactors. Both of these technologies require the use of high-temperature molten salt. To implement these technologies, one must understand the electrochemical behavior of fission products in molten salts, lanthanides, and actinides. In this study, a rotating-disk-electrode (RDE) measurement system for high-temperature molten salts is constructed and tested by investigating the electrochemical reactions of Sm3+ in LiCl–KCl melts. The results show that the reduction of Sm3+ presents the Levich behavior in LiCl–KCl melts. Using the RDE system, not only is the diffusion-layer thickness of Sm3+ measured in high-temperature molten salts but also various electrochemical parameters for Sm3+ in LiCl–KCl melts, including the diffusion coefficient, Tafel slope, and exchange current density, are determined.

악성 간문부 담관 폐쇄(malignant hilar biliary obstruction, MHBO) 치료를 위해 시행되는 내시경 담관배액술은 후속 치료, 생존율 및 환자 삶의 질 향상에 필수적이다. 그러나 간문부 담관의 복잡한 해부학적 특징으로 인해 시술의 난이도가 높고 시술 관련 우발증의 위험이 있다. 본 고에서는 완전 피막형 자가팽창성 금속 스텐트(fully covered self-expandable metal stent, fcSEMS)를 이용한 나란한 양측 삽입 담관배액술을 시행 후 근위부 담관내 이탈(proximal stent migration)이 발생한 증례를 보고한다. 현재까지 MHBO에 대해서는 어떤 종류의 스텐트를 어떠한 방법으로 시술할지에 대하여 충분한 근거가 정립되어 있지는 않다. 그렇지만 본 증례와 같이 fcSEMS를 사용할 경우 스텐트 이탈 위험성이 ucSEMS보다 높다는 것은 인지하고 있어야 하겠으며, 환자 진료 시 이러한 사항을 고려하여 적절한 대비가 필요하겠다. 향후 이러한 스텐트 이탈을 줄일 수 있는 다양한 예방법이 고안된다면 많은 도움이 될 것으로 기대 된다.

Graphene-based materials modified with transition metals, and their potential utilization as hydrogen storage devices, are extensively studied in the last decades. Despite this widespread interest, a comprehensive understanding of the intricate interplay between graphene-based transition metal systems and H2 molecules remains incomplete. Beyond fundamental H2 adsorption, the activation of H2 molecule, crucial for catalytic reactions and hydrogenation processes, may occur on the transition metal center. In this study, binding modes of H2 molecules on the circumcoronene (CC) decorated with Cr or Fe atoms are investigated using the DFT methods. Side-on (η2-dihydrogen bond), end-on and dissociation modes of H2 binding are explored for high (HS) and low (LS) spin states. Spin state energetics, reaction energies, QTAIM and DOS analysis are considered. Our findings revealed that CC decorated with Cr (CC-Cr) emerges as a promising material for H2 storage, with the capacity to store up to three H2 molecules on a single Cr atom. End-on interaction in HS is preferred for the first two H2 molecules bound to CC-Cr, while the side-on LS is favored for three H2 molecules. In contrast, CC decorated with Fe (CC-Fe) demonstrates the capability to activate H2 through H–H bond cleavage, a process unaffected by the presence of other H2 molecules in the vicinity of the Fe atom, exclusively favoring the HS state. In summary, our study sheds light on the intriguing binding and activation properties of H2 molecules on graphene-based transition metal systems, offering valuable insights into their potential applications in hydrogen storage and catalysis.

High-entropy alloys (HEAs) have been reported to have better properties than conventional materials; however, they are more expensive due to the high cost of their main components. Therefore, research is needed to reduce manufacturing costs. In this study, CoCrFeMnNi HEAs were prepared using metal injection molding (MIM), which is a powder metallurgy process that involves less material waste than machining process. Although the MIM-processed samples were in the face-centered cubic (FCC) phase, porosity remained after sintering at 1200°C, 1250°C, and 1275°C. In this study, the hot isostatic pressing (HIP) process, which considers both temperature (1150°C) and pressure (150 MPa), was adopted to improve the quality of the MIM samples. Although the hardness of the HIP-treated samples decreased slightly and the Mn composition was significantly reduced, the process effectively eliminated many pores that remained after the 1275°C MIM process. The HIP process can improve the quality of the alloy.

The development of thermoelectric (TE) materials to replace Bi2Te3 alloys is emerging as a hot issue with the potential for wider practical applications. In particular, layered Zintl-phase materials, which can appropriately control carrier and phonon transport behaviors, are being considered as promising candidates. However, limited data have been reported on the thermoelectric properties of metal-Sb materials that can be transformed into layered materials through the insertion of cations. In this study, we synthesized FeSb and MnSb, which are used as base materials for advanced thermoelectric materials. They were confirmed as single-phase materials by analyzing X-ray diffraction patterns. Based on electrical conductivity, the Seebeck coefficient, and thermal conductivity of both materials characterized as a function of temperature, the zT values of MnSb and FeSb were calculated to be 0.00119 and 0.00026, respectively. These properties provide a fundamental data for developing layered Zintl-phase materials with alkali/alkaline earth metal insertions.

Additive Manufacturing (AM) is a process that fabricates products by manufacturing materials according to a three-dimensional model. It has recently gained attention due to its environmental advantages, including reduced energy consumption and high material utilization rates. However, controlling defects such as melting issues and residual stress, which can occur during metal additive manufacturing, poses a challenge. The trial-and-error verification of these defects is both time-consuming and costly. Consequently, efforts have been made to develop phenomenological models that understand the influence of process variables on defects, and mechanical/ electrical/thermal properties of geometrically complex products. This paper introduces modeling techniques that can simulate the powder additive manufacturing process. The focus is on representative metal additive manufacturing processes such as Powder Bed Fusion (PBF), Direct Energy Deposition (DED), and Binder Jetting (BJ) method. To calculate thermal-stress history and the resulting deformations, modeling techniques based on Finite Element Method (FEM) are generally utilized. For simulating the movements and packing behavior of powders during powder classification, modeling techniques based on Discrete Element Method (DEM) are employed. Additionally, to simulate sintering and microstructural changes, techniques such as Monte Carlo (MC), Molecular Dynamics (MD), and Phase Field Modeling (PFM) are predominantly used.