This study aims to examine the validity of current environmental safety standards and propose necessary improvements to minimize health risks posed by heavy metals in children’s activity zones. Compared to adults, children are more vulnerable to hazardous substances, and exposure to heavy metals can severely impact their neurological development and physical growth. In Korea, the amendment of the Enforcement Rules of the Environmental Health Act (Annex 4-20) in July 2021 reduced the acceptable threshold for lead (Pb) in paints and finishing materials used in children’s activity zones. However, regulatory standards for other heavy metals remain insufficient. Therefore, this research investigates and analyzes both domestic and international standards for heavy metals in commonly used materials such as wallpaper, flooring, finishing materials, and paints. This paper proposes guidelines for improving current regulatory criteria based on scientific validity and potential exposure. The findings are expected to serve as foundational data for advancing proactive environmental safety management strategies to better protect children’s health.

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.

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.