Eu-doped SrAl2O4 is a promising thermoluminescent and mechanoluminescent material with high brightness and stability, making it suitable for various luminescent devices. In this study, SrAl2O4:Eu was synthesized using a solid-state reaction method, and the effects of reducing atmosphere and high-temperature synthesis conditions on its luminescence properties were systematically analyzed. The luminescence characteristics of SrAl2O4:Eu were found to be highly sensitive to synthesis temperature, atmosphere, and Eu doping concentration, and optimal conditions were determined. A comparison of SrAl2O4:Eu synthesized at 1,300 °C under air and reducing atmospheres revealed that the reducing atmosphere plays a critical role in stabilizing Eu2+ ions, forming a single-phase SrAl2O4, and establishing luminescence centers. Notably, SrAl2O4:Eu synthesized at 1,600 °C in a reducing atmosphere achieved a photoluminescence quantum yield (PLQY) of 43 % and a maximum luminance of 2,030 Cd/m2, showing significant improvement in luminescence efficiency compared to samples synthesized at 1,300 °C. When Eu doping concentrations were adjusted from 1 % to 20 %, the highest luminescence performance was observed at 10 % doping, while excessive doping (20 %) increased non-radiative recombination pathways, and no further improvement in luminescence efficiency was observed. X-ray Diffraction (XRD) and Photoluminescence (PL) analyses elucidated the effects of synthesis conditions on the structural stability and luminescence properties of SrAl2O4:Eu, and the optimal reducing atmosphere and high-temperature synthesis conditions are proposed. This study provides a synthesis strategy for enhancing the luminescence properties of Eu-doped SrAl2O4 and lays the groundwork for the development of highperformance thermoluminescent and mechanoluminescent materials.

본 연구에서는 친환경적이고 경제적인 수용액 환경에서 금속-유기 골격체(metal-organic frameworks, MOF)인 UiO-66을 합성하는 방법을 개선하고, 합성 조건이 UiO-66의 표면적 및 결정성에 미치는 영향을 분석하였다. 합성 실험은 금 속 용액과 리간드 용액의 주입 순서 및 계면활성제(Tween 20)의 첨가 유무를 변화시키며 진행하였다. 그 결과, 리간드 용액 을 금속 용액에 주입하고 계면활성제를 사용하지 않은 경우, 표면적과 결정성이 더 높은 UiO-66을 얻을 수 있었다. SEM 및 XRD 분석 결과, 계면활성제의 첨가는 입자 크기와 결정 구조에 큰 변화를 주지 않았으나, BET 분석 결과 표면적 감소가 확 인되었다. 이는 합성 과정에서 계면활성제가 핵 형성과 결정 성장에 영향을 미칠 수 있음을 시사한다. 본 연구 결과는 수용액 기반 UiO-66 합성법의 최적화, 대규모 제조 공정 및 다양한 산업적 응용에 유용한 정보를 제공할 수 있을 것이다.

We report the synthesis of bimetallic Cu-Au nanotubes (NTs) and Cu@Au core-shell nanowires (NWs) for use as anti-oxidative electrodes. The fabrication involved two key approaches: galvanic replacement to produce Cu-Au NTs and the physical deposition of Au to form Cu@Au core-shell NWs. The galvanic replacement process generated hollow NTs through the Kirkendall effect, driven by the unequal diffusion rates of Cu and Au during the redox reaction. In contrast, the physical deposition of Au, facilitated by fast reduction kinetics using L-ascorbic acid, enabled the formation of a Au shell encapsulating the Cu NWs, preserving their structural integrity. Morphological and structural analyses confirmed the successful formation of both nanostructures. While the Cu-Au NTs exhibited hollow interiors and increased dimensions, the Cu@Au NWs displayed a solid core-shell morphology with minimal diameter increase. Electrical conductivity and thermal stability tests revealed the superior performance of the Cu@Au NWs. The sheet resistance of Cu@Au NWs remained as low as 4 Ω sq-1 and showed exceptional thermal stability, with minimal resistance variation (R/Ro ~1.36) even after 36 h at 120 °C under ambient conditions. In contrast, the Cu-Au NTs suffered rapid oxidation and structural instability. The physical deposition approach holds significant promise for the development of robust, low-resistance electrodes for long-term applications in harsh environments.

Iron oxide (ε-Fe2O3) is emerging as a promising electromagnetic material due to its unique magnetic and electronic properties. This review focuses on the intrinsic properties of ε-Fe2O3, particularly its high coercivity, comparable to that of rare-earth magnets, which is attributed to its significant magnetic anisotropy. These properties render it highly suitable for applications in millimeter wave absorption and high-density magnetic storage media. Furthermore, its semiconducting behavior offers potential applications in photocatalytic hydrogen production. The review also explores various synthesis methods for fabricating ε-Fe2O3 as nanoparticles or thin films, emphasizing the optimization of purity and stability. By exploring and harnessing the properties of ε-Fe2O3, this study aims to contribute to the advancement of next-generation electromagnetic materials with potential applications in 6G wireless telecommunications, spintronics, high-density data storage, and energy technologies.

Nitrogen-doped carbon nanomaterials (N-CNMs) were prepared using Ni(NO3)2 as a catalyst in the laminar diffusion flame. Doping the structure of carbon nanomaterials (CNMs) with nitrogen can significantly change the characteristics of CNMs. The purpose of this research is to study the effect of adding ammonia ( NH3) on the evolution of CNMs structure in the laminar flame of ethylene. Raman analysis shows that the intensity ratio ( ID/IG) of the D-band and G-band of N-CNMs increases and then decreases after the addition of NH3. The intensity ratio is a maximum of 0.99, which has a good degree of disorder and defect density. The binding distribution of nitrogen was analyzed by X-ray photoelectron spectroscopy (XPS), and a correlation was found between the amount of nitrogen and the morphology of N-CNMs. Nitrogen atoms predominantly present in the forms of pyrrolic-N, pyridinic-N, graphitized-N and oxidized-N, with a doping ratio of nitrogen atoms reaching up to 2.44 at.%. This study found that smaller nickel (Ni) nanoparticles were the main catalysts for carbon nanotubes (CNTs), and their synthesis followed the ‘hollow growth mechanism’ and carbon nanofibers (CNFs) were synthesized from larger Ni nanoparticles according to the ‘solid growth mechanism’. Furthermore, a growth mechanism for the synthesis of bamboolike CNTs using a specific particle size of the Ni catalyst is proposed. It is noteworthy that the synthesis and modulation of high-performance N-CNMs by flame method represents a simple and efficient approach.

With the continuing advances in technology, electrical energy storage has become increasingly important. Among storage devices supercapacitors’ distinct qualities, such as a long lifespan, quick charge/discharge speeds, and high-power density, make them viable substitutes for traditional batteries. In this study a simple hydrothermal method was used to synthesize a h-MoO3/graphene oxide (GO) composite for such applications. The crystal structure, morphology, and chemical bonding were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and Raman spectroscopy. XRD confirmed the hexagonal crystal structure, and no changes were observed after GO incorporation. The FESEM images revealed that the nanosheets of GO and hexagonal rods MoO3 were well coupled with the GO sheets. The electrochemical properties of the pure h-MoO3 and h-MoO3/GO composites were studied using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). The nanocomposite electrode demonstrated a specific capacitance of 134 Fg-1 at a current density of 3 mA/cm-2, an energy density of 26.8 Wh/kg-1, and power density of 560 W/kg-1 in an aqueous acidic electrolyte 1 M H2SO4, which is notably higher than that of pure MoO3. This indicates the promising electrochemical performance of MoO3/GO composite for supercapacitor applications. The enhanced capacitive performance may have resulted from the decrease in the charge transfer resistance (Rct), calculated from the Nyquist plot. Furthermore, the composite material exhibited stability and a capacitive retention of 76 % after 1,000 cycles. This confirms the benefits of incorporating GO to enhance material retention for better long-term results. The results of this study demonstrate its potential to advance energy storage technology. Maintaining the hexagonal crystal structure of h-MoO3 while incorporating GO improves the composite’s structural stability, an important factor for reliable long-term use. Moreover, the observed reduction in crystallite size due to the presence of GO suggests improved electrochemical performance.

Purpose: This study aimed to integrate and synthesize the recovery experiences of stroke patients through a qualitative meta-synthesis methodology. Methods: By searching through Korean databases(RISS, DBpia, KISS, NDSL), we compared 12 qualitative studies on recovery experiences of stroke patients. The meta-synthesis process was primarily guided by Noblit and Hare’s approach. Results: The common central experience of stroke patients was “reaching the world again”. Findings from the literature reviewed were synthesized into four themes: ‘earnest desire for recovery’, ‘rediscovery of family’, ‘duet of hope and despair’, ‘designing a new life’. Conclusion: The findings of this study provides a deeper understanding of recovery experiences of stroke patients. And this finding will serve as the basis for educational programs for health care personnel and families caring for stroke patients, development of programs to promote recovery of stroke patients, and self-help groups.

In this study, ferric phosphate precursors were prepared by controlling precipitation time, and the resulting LiFe PO4 active materials were thoroughly investigated. Microscale LiFePO4 cathode materials, designed for high energy density at the cell level, were successfully synthesized through a 10 h co-precipitation. As the reaction time increased, smaller primary particles were aggregated more tightly, and the secondary particles exhibited a more spherical shape. Meanwhile, ammonia did not work effectively as a complexing agent. The carbon coated LiFePO4 (LiFePO4/C) synthesized from the 10 h ferric phosphate precursor exhibited larger primary and secondary particle sizes, a lower specific surface area, and higher crystallinity due to the sintering of the primary particles. Enhanced battery performance was achieved with the LiFePO4/C that was synthesized from the precursor with the smaller size, which exhibited the discharge capacity of 132.25 mAh ‧ g-1 at 0.1 C, 70 % capacity retention at 5 C compared with 0.1 C, and 99.9 % capacity retention after the 50th cycle. The better battery performance is attributed to the lower charge transfer resistance and higher ionic conductivity, resulting from smaller primary particle sizes and a shorter Li+ diffusion path.

Among the products of the electrocatalytic reduction of carbon dioxide (CO2RR), CO is currently the most valuable product for industrial applications. However, poor stability is a significant obstacle to CO2RR. Therefore, we synthesized a series of bimetallic organic framework materials containing different ratios of tungsten to copper using a hydrothermal method and used them as precursors. The precursors were then subjected to pyrolysis at 800 °C under argon gas, and the M-N bimetallic sites were formed after 2 h. Loose porous structures favorable for electrocatalytic reactions were finally obtained. The material could operate at lower reduction potentials than existing catalysts and obtained higher Faraday efficiencies than comparable catalysts. Of these, the current density of WCu-C/N (W:Cu = 3:1) could be stabilized at 7.9 mA ‧ cm-2 and the FE of CO reached 94 % at a hydrogen electrode potential of -0.6 V (V vs. RHE). The novel materials made with a two-step process helped to improve the stability and selectivity of the electrocatalytic reduction of CO2 to CO, which will help to promote the commercial application of this technology.

목적 : 본 연구에서는 젤라틴 메타크릴레이트(GelMA)를 합성하고 이를 기본 하이드로겔 렌즈 혼합물과 함께 교 반한 후 제조된 렌즈의 물성을 비교 분석하여 고기능성 소재로서의 적용성을 확인하고자 하였다. 방법: 젤라틴 메타크릴레이트(GelMA) 합성에는 젤라틴(A형), 인산완충식염수(Phosphate buffer solution, PBS), methacrylic anhydride(MA)를 사용하였다. 또한, 주재료인 2-hydroxyethyl methacrylate(HEMA)와 광 개시제인 2-Hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone(Irgacure 2959), 교차결합제인 ethylene glycol dimethacrylate(EGDMA)를 각각 사용하였다. 제조된 렌즈의 물성 분석을 위해 광투과도, 굴절률, 함수율, 접촉각을 평가하였다. 결과: GelMA의 합성은 EDS를 통해 확인되었다. 제조된 렌즈의 물성을 측정한 결과, 가시광선 투과도는 91.33~ 71.02%, 굴절률은 1.4383~1.4365, 함수율은 39.08~39.04%, 접촉각은 70.83~70.43°로 나타났으며, GelMA 첨가 비율이 증가할수록 굴절률이 증가하였다. 결론 : GelMA 첨가 시 하이드로겔 렌즈의 함수율과 습윤성에 영향을 미치지 않으면서 굴절률 증가에 효과적이 며 UV-B 및 UV-A 영역을 차단하는 기능을 나타내었다. 따라서 본 연구 결과, GelMA가 첨가된 하이드로겔 소 재는 고굴절률 및 시기능성 렌즈 소재로 다양하게 활용될 수 있을 것으로 판단된다.

Today, the principles of green chemistry are being fundamentally applied in the chemical industry, such as the nitrobenzene industry, which is an essential intermediate for various commercial products. Research on the application of response surface methodology (RSM) to optimize nitrobenzene synthesis was conducted using a sulfated silica (SO4/SiO2) catalyst and batch microwave reactor. The nitrobenzene synthesis process was carried out according to RSM using a central composite design (CCD) design for three independent variables, consisting of sulfuric acid concentration on the silica (%), stirring time (min), and reaction temperature (°C), and the response variable of nitrobenzene yield (%). The results showed that a three-factorial design using the response surface method could determine the optimum conditions for obtaining nitrobenzene products in a batch microwave reactor. The optimum condition for a nitrobenzene yield of 63.38 % can be obtained at a sulfuric acid concentration on the silica of 91.20 %, stirring time of 140.45 min, and reaction temperature of 58.14 °C. From the 20 experiments conducted, the SO4/SiO2 catalyst showed a selectivity of 100 %, which means that this solid acid catalyst can potentially work well in converting benzene to nitrobenzene.

In this work, we investigated the photo-degradation performance of MnO2-SiC fiber-TiO2 (MnO2-SiC-TiO2) ternary nanocomposite according to visible light excitation utilizing methylene blue (MB) and methyl orange (MO) as standard dyes. The photocatalytic physicochemical characteristics of this ternary nanocomposite were described by X-ray diffraction (XRD), scanning electron microscopy (SEM), tunneling electron microscopy (TEM), ultraviolet-visible (UV-vis), diffuse reflectance spectroscopy (DRS), electrochemical impedance spectroscopy (EIS), photocurrent and cyclic voltammogram (CV) test. Photolysis studies of the synthesized MnO2-SiC-TiO2 composite were conducted using standard dyes of MB and MO under UV light irradiation. The experiments revealed that the MnO2-SiC-TiO2 exhibits the greatest photocatalytic dye degradation performance of around 20 % with MB, and of around 10 % with MO, respectively, within 120 min. Furthermore, MnO2-SiC-TiO2 showed good stability against photocatalytic degradation. The photocatalytic efficiency of the nanocomposite was indicated by the adequate photocatalytic reaction process. These research results show the practical application potential of SiC fibers and the performance of a photocatalyst composite that combines these fibers with metal oxides.

Purpose: To review systematically the qualitative research related to the patient-safety competence of nurses based on nurses’ nursing experiences, synthesizing the results understanding. Method: The well-known Thomas and Harden meta-synthesis method was applied. Five databases were searched for relevant literature: CINAHL , RISS , DBpia, KISS, NDSL. Results: Six qualitative studies were selected for review. Three themes were synthesized: patient-safety incidents and patient-safety competency of nurses in emergency situations; processes to advance patient-safety competency in nursing; advancing patient-safety competency in nursing. Eight subthemes were identified. Conclusion: This study improved the understanding of nurses’ experiences in terms of patient-safetycompetenc. Based on systematic review and meta-synthesis of basic patient-care data, study results suggest a direction for the development of patient-safety competencies in nursing and provide evidence for further research.

반응성 에시드 클로라이드인 트리멜리틱 안하이드라이드 클로라이드를 이용한 2-에티닐피리딘의 무촉매중 합을 통하여 트리멜리틱 부분을 측쇄로 갖는 이온성 공액구조 고분자를 합성하였다. 2-에티닐피리딘과 트리멜리틱 안하이드라이드 클로라이드를 1:1 몰비로 DMF 용매에서 반응시킨 결과 해당 공액구조 고분자를 높은 수율로 합성 할 수 있었다. 첫 번째 반응 단계에서 만들어진 단량체인 N-치환-2-에티닐피리디늄 염은 별도의 촉매 사용없이도 중합반응이 잘 진행되었다. NMR, IR, UV-visible 등의 분광분석기를 사용하여 합성 고분자의 구조를 분석한 결과 설계한 치환기를 갖는 공액구조 고분자가 합성되었음을 확인할 수 있었다. 합성 고분자의 전기-광학적 특성과 전기 화학적 특성을 측정하였다. 본 고분자는 자외선 영역뿐만 아니라 가시광선 영역에서 500 nm까지 넓은 흡수 피크 를 보였으며 PL 최대값은 539 nm에서 나타났다.

The separation of zirconium and hafnium using tributyl phosphate (TBP)-Dodecane extractants in nitric acid medium was performed. Zirconium oxychloride, used as extraction feed, was obtained from the synthesis of Kalimantan zircon sand concentrate smelted using NaOH. The extraction process was carried out by dissolving chloride-based metals in nitric acid media in the presence of sodium nitrate using TBP-Dodecane as an extractant. Some of the extraction parameters carried out in this study include variations in organic phase and aqueous phase (O/A), variations in contact time, and variations in nitric acid concentration. Extraction was carried out using a mechanical shaker according to the parameter conditions. X-ray fluorescence (XRF) was used for elemental (Zr and Hf) composition analysis of the aqueous solution. The results showed that zirconium was separated from hafnium at optimum conditions with an organic/aqueous ratio of 1:5, contact time of 75 min, and an HNO3 concentration of 7 M. The resulting separation factor of zirconium and hafnium using TBP-Dodecane was 14.4887.