Despite boron nitride's (BN) exceptional physical performance and durability, the current lack of a systematic methodology for BN processing, which stems from its extreme robustness, often necessitates the use of additive materials, thereby frequently sacrificing its desirable properties. Here, we report binder-free BN monoliths derived from a suspension with tunable rheology and long-term colloidal stability. The control of solvent affinity allows the production of two distinct BN morphologies: (1) physically exfoliated, large-size BN flakes (p-BN) and (2) mechanochemically produced, small-size BN particles (m-BN) with hydroxyl-functionalized edges. Crucially, the interfacial interactions and aspect ratio complementarity between the two BN components enable spontaneous co-assembly into a long-term stable, binder-free suspension with programmable rheology. The resulting binder-free BN films exhibit a 19-fold enhancement in cohesive energy (3.8 J·m- 2 vs. 0.20 J·m- 2 for p-BN), high in-plane thermal conductivity (>40.6 W·m- 1·K- 1), and a neutron absorption coefficient of 28.3 cm- 1, offering a promising solution for advanced aerospace, nuclear, and optoelectronic systems operating under severe environmental constraints.

This study uses neutron beam diffraction to nondestructively analyze microstructures in specimens produced through replicated ancient Korean heat treatment techniques. As a result of an experiment using SK5 steel with varying quenching times (1, 5, and 10 s) and clay thicknesses (0, 1, and 3 mm), the largest amount of martensite was generated when the quenching time was 5 s. Four specimens were examined: one before and three after heat treatment. Optical and scanning electron microscopy revealed ferrite structures in the specimen before heat treatment, martensite in the specimen after heat treatment (0 mm, 5 s), and pearlite in the remaining specimen after heat treatment. Neutron beam diffraction analysis quantified peak broadening under tensile stress. All specimens demonstrated increased peak broadening upon tensile deformation, with significant differences in the peak positions and widths between the heat treatment specimen and heat-treated specimens due to microstructural variations. Meanwhile, heat-treated specimens demonstrated greater peak width increases than before heat treatment specimens, indicating higher defect concentrations in the before heat treatment specimens. Results confirmed that martensite formation could be identified nondestructively. However, as accurate structure identification is not possible with neutron beam diffraction analysis alone, neutron imaging technology is required.

A more efficient use of energy can be achieved by improving the performance of evaporator plate heat exchangers (PHEs). This will allow for the use of low-GWP (Global Warming Potential) refrigerants, such as R513A, which will lead to the assembly of smaller, more reliable, and less harmful thermal systems. Instead of using sandblasting or copper electroplating, which can lead to issues including uneven coatings, plate deformation, and oxidation, electrochemical etching is a superior choice for surface modification. This study employs electrochemical etching to generate microroughness on the heat transfer surface for enhancing evaporative heat transfer of the flow of low GWP refrigerant R-513A inside PHE. Heat transfer experiment was conducted suing three surfaces with different average roughness values of 2.00, 9.98, and 13.27 mu m generated by etching method on stainless steel PHE. The results show that microroughness can increase heat transfer coefficients (HTCs) by up to 28 % compared to smooth surfaces. This is mostly because there is more turbulence at the wall-liquid interface, but it also causes higher pressure drops because the flow is more resistant. An artificial neural network (ANN) model was designed to more effectively capture these complex relationships, surpassing traditional empirical correlations in forecasting both HTCs and frictional pressure reductions. The findings confirm that electrochemical etching is an effective surface enhancement method for evaporator PHEs and illustrates the robust predictive ability of ANN models, providing a viable approach for the optimized design of high-efficiency, environmentally sustainable heat exchangers.

The relationship between boron content and thermal neutron attenuation coefficient was examined in fifteen kinds of borated stainless steels alloyed with the weight percentage of 0.19-1.87 boron. The attenuation coefficients were measured by the ratio of the neutron intensity transmitted by the borated stainless steel to the initial intensity without transmission. The neutron intensity was analyzed by the diffraction peak with the wavelengths of 0.131, 0.146, and 0.1836 nm. The result shows that the attenuation coefficient of 1.491 cm-1 increases up to 5.412 cm-1, which means a significant decrease of the peak intensity, as the boron content increases from 0.19 wt% to 1.87 wt% in the borated stainless steels. It is attributed to the high areal density (g/ cm2) of 10B isotope in the natural boron, which has a large neutron microscopic cross-section. The measured attenuation coefficients are comparable to the theoretically calculated ones based on the microscopic cross-sections of contained elements in each alloy. Besides, it is proportional to the neutron wavelength due to the decrease of the neutron energy. This paper provides the correlation among the boron content, specimen thickness, and transmission ratio of thermal neutrons at wavelengths in the borated stainless steels.

The ginseng plant is threatened with extinction owing to the prevalence of soil-borne pathogens and water shortage in field cultivation due to climate change. To optimize water management in controlled cultivation that can sustain ginseng production, a 3D neutron imaging method was developed to quantitatively measure water content of roots growing in soil. It was determined that, according to a Monte Carlo simulation, the neutron penetration rate is 32 %, which allows quantitative measurement of water thicknesses up to 30 mm in aluminum phantom using 3D neutron imaging. In the simulation, the aluminum phantom was buried in soil with 12 % moisture content contained in a 50 mm diameter aluminum pot. In practical experiments, the neutron penetration rate of an aluminum phantom buried in soil with a moisture content of 7.7 % was 18 % at a water thickness of 30 mm. A calibration curve was created to quantitatively measure the water content of aluminum phantom buried in aluminum pot soil with 1.3 similar to 7.7 % moisture. The water content of 3-year-old ginseng roots growing in aluminum pot soil with a moisture content of 7.7 % was quantitatively determined to be 70.0 % (+/- 5 %), 55.0 % (+/- 5 %) and 70.0 % (+/- 5 %) on the basis of the calibration curve. It is concluded that, the in vivo 3D neutron imaging is a unique way to analyze the hydrology throughout the seedling and culturing stages of plant roots in soil for controlled cultivation.

This study compared the corrosion thickness of iron artifacts using both non-destructive and destructive analytical methods. More specifically, the study evaluated the effectiveness of non-destructive neutron diffraction in measuring corrosion. Neutron diffraction analysis indicated a measurement error of approximately 6% when compared to the results of the other methods, confirming its applicability in assessing corrosion thickness in iron artifacts. The results were in line with those of previous studies. In addition, a results comparison with destructive analysis confirmed that the corrosion thickness of DPL(Dense Product Layer) could be estimated using the non-destructive neutron diffraction method when considering the characteristics of TM(Transformed Medium). This method of estimating the corrosion thickness and internal structures of iron artifacts through neutron analysis and without causing damage significantly enhances our understanding of iron corrosion while verifying its potential for use in practical applications.

Distinguishing differences between authentic artifacts and replicas is a significant challenge in the field of cultural heritage. In this study, we explore the application of neutron grating interferometry and tomography techniques to identify Korean copper coins in the nineteenth century of Joseon period by investigating structural differences between genuine objects and replicas. Neutron grating interferometry provides the microstructural information of coins, including features such as pores and precipitates, through a dark field image derived from small-angle neutron scattering. Additionally, neutron transmission tomography examines the three-dimensional internal structures and potentially hidden features of coins. Both neutron imaging techniques highlight regions that contain lead precipitates in the copper alloy, showing consistent agreement with optical imaging and with the quantitative lead content measured by energy dispersive X-ray spectroscopy. The distinct corrosion patterns observed in the authentic coin and replica provide empirical explanations for the general corrosion mechanism of copper alloy. This interpretation finds support in the moderate contribution of dark field contrast from cuprite, which underlies the signal of lead precipitates.

We study the bimodal imaging of neutron and X-ray simultaneous tomography in complementary ways and feasibility test for HANARO thermal neutron facility. This approach combines the advantages of x-rays, which exhibit low penetration for high atomic numbers, with neutrons that have high cross -sections for light elements such as Li, Be, and B. This combination allows for a comprehensive understanding of the internal structure of materials, extending the exploration range beyond what is possible with conventional x-ray and neutron technologies. We additionally demonstrate the correction of scattering in neutron images using black body techniques, which successfully enhances visibility and effectively reduces scattering-induced noise. Furthermore, we discuss the potential for quantitative and qualitative comparative evaluations by applying an unrolling method as a new approach to straighten bent or twisted objects. The results suggest the future applicability of neutron and x-ray simultaneous tomography at HANARO and indicate the potential for integration with quantitative techniques such as energy -selective imaging and interferometry.

This research employed electrochemical etching to generate microscale roughness on a plate heat exchanger (PHE) thereby enhancing condensation heat transfer in a vertical downward flow. The effects of the mass flux, vapor quality, heat flux, saturation temperature and microscale surface roughness on the condensation heat transfer coefficient (HTC) and frictional pressure drop (FPD) of R-513a flowing through a PHE was experimentally investigated. Experimental measurements were made under various heat fluxes of 5–15 kW/m2, mass fluxes of 60–80 kg/m2s, saturation temperatures of 40–50 °C, and mean vapor qualities of 0.1–0.7. HTC increased by up to 28, 26, 74, and 32.5 % as the heat flux, mass flux, average quality, and microscale surface roughness were respectively increased, but decreased by 19 % with the saturation temperature. FPD increased as the mass flux and average vapor quality increased, whereas it was reduced as the refrigerant saturation temperature increased. In contrast, the heat flux had little to no influence on FPD. Correlations for predicting the Nusselt number and friction factor were postulated by considering influential dimensionless numbers during heat transfer. Maximizing the Nusselt number and thermal performance factor was ultimately resolved using a multi-objective genetic algorithm to find a Pareto front solution. Consequently, the optimal surface roughness was found to be 9.94 μm.

This study was conducted to confirm the possibility of using the corrosion products of iron artifacts and corrosion systems for non-destructive analysis using neutrons by applying the non-destructive analysis method and the destructive analysis method together to the analysis of the corrosion system of iron artifacts. As a result of transmission analysis, the shape of the artifact, the boundary between the metal layer and the corrosion layer, etc. could be confirmed, and through tomography, the shape, surface shape, and internal cross section of the artifact could be confirmed. It was confirmed that the corrosion thickness using the residual stress measurement method has a high reliability of less than 10% of an error compared to other analysis results, so it is highly likely to be used to measure the corrosion thickness. It was confirmed that the corrosion layer of the iron artifact analyzed this time was mainly Goethite among the types of DPL and was embedded with Magnetite/Maghemite. Since the neutron analysis can estimate the corrosion thickness non-destructive, it is highly likely to be used to study the corrosion rate of iron artifacts by burial environment through additional studies.

Lithium-ion batteries are widely used in electric vehicles because of their high capacity and voltage. However, some drawbacks to the battery stability exist. The aim of our research was to determine the optimum width and number of channels of a cold plate. To estimate the temperature distribution and heat transfer rate, the MSMD (multi-scale multi-dimensional) - Newman P2D model in ANSYS Fluent was used. Prior to comparing the heat transfer rates of the various battery surfaces using different cold plates, the surface temperature of the battery (LiFePO4) at discharge rates of 2C, 3C, and 4C was calculated to determine the battery characteristics. Subsequently, two cold plates were attached to both sides (front and back) of the batteries and the heat transfer rate of the battery surface in contact with the cold plate, and the pressure drop between the inlet and outlet of the channels during the discharge process were estimated. In addition, the j and f factors, which are used to estimate the cooling performance of the cold plates, were calculated. In determining the most efficient cold plate options, the trade-off between the heat transfer coefficient and the pressure drop is also important for the relationship between the two factors (j and f factors).

The geometrical effect of natural convection in an air channel with a cavity at the turning section was investigated experimentally by controlling the vertical upper gap (G, 100-75 mm) and horizontal lower channel gap (B, 100 -300 mm) and varying the heat load conditions (P, 1.35-6.20 kW). The thermal behavior in the channel was considered in terms of the temperature distributions of the walls, and the air temperature field was estimated from the measured air temperature. Additionally, the heat removal performance was analyzed for changes in each parameter to find the critical design parameter on cooling performance.The heat load condition positively affected the heat removal performance, but it did not affect the trend of the wall temperature distributions or the shape of the temperature field in the channel. A lower channel gap directly affected the cooling in the lower channel (cavity) between the lower curved wall and bottom but did not appreciably affect the cooling in the upper vertical channel between both vertical walls and overall heat removal performance (RSDMax = 3.2 %). As a result, the most critical parameter was the upper vertical channel gap because it affected both lower and upper channels and played a vital role in determining the overall heat transfer performance (RSDMax = 11.0 %). Additionally, it was confirmed that the location where the peak wall temperature appeared changed as the vertical gap size was altered.Interestingly, we found that the transition phenomenon eliminating the entrance effect occurred above the mid-height of the vertical channel in all experimental cases, and it was directly related to the heat removal performance. The temperature profiles developed smoothly along the height in only the G175 cases, which were the maximum heat removal performance cases, owing to the minimized entrance effect in the channel. In contrast, the temperature profiles below the mid-height of the vertical channel changed rapidly due to the entrance effect in other cases.(c) 2022 Elsevier Ltd. All rights reserved.

Neutron shielding material is important for storage and shipping cask of spent nuclear fuel, and the demand for neutron shielding materials is steadily increasing because there is not enough space in the temporary storage anymore [1]. However, Neutron shielding materials depend entirely on imports. Some research group of Korea have studied and developed Fe based neutron shielding materials for localization [2, 3]. After fabrication of neutron shielding materials, neutron transmission and macroscopic cross section of prepared samples were measured to evaluate neutron shielding ability using neutron imaging.

Alzheimer’s disease (AD) is an inflammatory neurodegenerative condition characterized by deposition of amyloid beta (Abeta) in the brain and origins dementia. Neuronal apoptosis following neuroinflammation by Abeta impairs cognition and memory. In this study we focused on Taurodeoxyxcholate (TDCA) is an active bile acid derivative with potent anti-inflammatory function. In 5× Familial Alzheimer’s disease (5xFAD) mice model, chronic administration of TDCA in 5xFAD mice improved learning and memory in different memory test compared with PBS group. TDCA treatment significantly decreased neuronal apoptosis, load of Abeta plaques, the number of activated GFAP+ astrocytes and Iba-1+ microglia in different brain region of 5xFAD mice. CD11bhiGr1intF4/80+ myeloid cells in brain and spleen increased significantly in TDCA-treated group compared to PBS-treated group when brain single cell were immune-stained. In vitro, TDCA increased phagocytosis of Abeta. TDCA suppressed NLRP3-ASC oligomerization and production of mature IL-1β/IL-18 in Microglia by Abeta. TDCA inhibited Ca++ influx incurred by ATP or BzATP (P2X7 agonists). Compared with wild type, Ca++ influx of macrophages from TGR5 KO mice was like that of P2X7 KO mice in response to BzATP, suggesting that TDCA might play role as an inverse agonist for TGR5 complexed with P2X7. TDCA activates adenylate cyclase and cAMP inhibit priming phase of inflammasomal activation and oligomerization of NLRP3-ASC complex, suggesting that TDCA suppresses both priming and activation phase of NLRP3 inflammasome. TDCA and its novel chemical derivatives could be better choice in ameliorating broad spectrum of neuroinflammation to improve cognition and memory in AD patients.

This paper demonstrates the possible nondestructive analysis of iron artifacts’ metallurgical characteristics using neutron imaging. Ancient kingdoms of the Korean Peninsula used a direct smelting process for ore smelting and iron bloom production; however, the use of iron blooms was difficult because of their low strength and purity. For reinforcement, iron ingots were produced through refining and forge welding, which then underwent various processes to create different iron goods. To demonstrate the potential analysis using neutron imaging, while ensuring artifacts’ safety, a sand iron ingot (SI–I) produced using ancient traditional iron making techniques and a sand iron knife (SI–K) made of SI–I were selected. SI–I was cut into 9 cm2, whereas the entirety of SI–K was preserved for analysis. SI–I was found to have an average grain size of 3 μm, with observed α-Fe (ferrite) and pearlite with a body-centered cubic (BCC) lattice structure. SI–K had a grain size of 1–3 μm, α-Ferrite on its backside, and martensite with a body-centered tetragonal (BCT) structure on its blade. Results show that the sample’s metallurgical characteristics can be identified through neutron imaging only, without losing any part of the valuable artifacts, indicating applicability to cultural artifacts requiring complete preservation.

FoxP3 reporter mice expressing green fluorescence protein (GFP) have been used as a very convenient tool to investigate the impact of regulatory T (Treg) cells on pathogenesis in autoimmune diseases. Here, we found that GFP-FoxP3(+) knock-in (KI) mice showed alterations in the production of anti-nuclear autoantibodies (ANAs) and nephritis with different extent, depending on the presence or absence of lupus susceptibility gene locus 1 (Sle1) and KI method: contrasting with B6.Sle1.fGFP-FoxP3 mice, expressing GFP via N-terminal insertion, B6.Sle1.iGFP-FoxP3, expressing GFP via bicistronic internal ribosome entry site-driven promotion, exhibited significantly lower penetrance of serum ANA, comparing to control B6.Sle1 mice. Moreover, B6.Sle1.GFP-FoxP3(+) mice reduced the Sle1-induced splenomegaly and B-cell expansion independently of the KI method employed, mainly by reducing the numbers of transitional 1 (T1) B cells and CD21(-)CD23(-) B cells, including plasmablasts and plasma cells. The absolute numbers of both splenic CD4(+) T cells and Treg cells from B6.Sle1.GFP-FoxP3 KI mice were significantly reduced but their proportion was not changed, compared to B6.Sle1 mice. Although the glomerular basement membranes were thickened in both B6.Sle1 and B6.Sle1.iGFP-FoxP3 mice, they were thinner in B6.Sle1.fGFP-FoxP3 mice. The latter mice expressed more nephrophilic autoantibodies and deposited more complement component 3 in glomeruli compared to B6.iGFP-FoxP3 mice. FoxP3(+) Treg cells may modulate B-cell tolerance in lupus-prone B6.Sle1 mice, presumably by modulating pathogenic, nephrophilic autoantibody production and nephritis.

초 록 본 연구는 전통제철법인 정련 및 단접을 적용한 사철강괴(SI)의 미세조직을 파괴분석법인 현미경분석과 비파괴분석법인 중성자 영상 분석을 통해 분석결과를 비교하였다.시료는 전통제 철법으로 생산한 사철강괴이며, 파괴분석용의 SI-A와 비파괴분석용의 9 cm 2 의 SI-B를 제작하였 다. 파괴분석으로 금속현미경과 주사전자현미경이 이용되었으며, 비파괴분석으로 일본 훗카이 도 대학의 소형 중성자원 이용시설을 통한 중성자 영상 분석을 이용하였다.파괴분석결과 미세 한 ferrite 및

본 연구는 전통제철법인 정련 및 단접을 적용한 사철강괴(SI)의 미세조직을 파괴분석법인 현미경분석과 비파괴분석법인 중성자 영상 분석을 통해 분석결과를 비교하였다. 시료는 전통제 철법으로 생산한 사철강괴이며, 파괴분석용의 SI-A와 비파괴분석용의 9 cm2의 SI-B를 제작하였 다. 파괴분석으로 금속현미경과 주사전자현미경이 이용되었으며, 비파괴분석으로 일본 훗카이 도 대학의 소형 중성자원 이용시설을 통한 중성자 영상 분석을 이용하였다. 파괴분석결과 미세 한 ferrite 및 pearlite가, 시료의 가장자리에서 Widmanstatten ferrite와 조대한 ferrite가 관찰되었다. 또한 비파괴분석법인 중성자 영상 분석 결과 체심입방격자 구조의 grain size가 3 μm 정도의 α-Fe 인 ferrite와 층상의 pearlite가 관찰되었다. 이렇듯 중성자 영상 분석을 이용하면 비파괴로 연구대 상의 재료과학적 특성을 확인할 수 있고 문화재에 적용 시 최적의 연구결과를 얻을 수 있음을 확인하였다.