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Effects of decay heat and cooling condition on the reactor pool natural circulation under RVACS operation in a water 2-D slab model
No full textThe temperature distribution of the reactor pool under natural circulation induced by the RVACS oper-ation was experimentally studied. According to the Bo' based similarity law, which could reproduce the temperature distribution of the working fluid under natural circulation, SINCRO-2D facility was designed based on the PGSFR. It was reduced to 1 : 25 in length scale, having water as a simulant of the sodium, which is the original working fluid. In general, temperature was stratified, however, effect of the natural circulation flow could be observed by the entrainment of the stratified temperature. Relative cooling contribution of the upper plenum (narrow gap) and lower plenum was approximately 0.2 and 0.8, respectively. In the range of decay heat from 0.2% to 1.0%, only the magnitude of the temperature was changed, while the normalized temperature maintained. Boundary temperature distribution change made a global temperature offset of the pool, without a significant local change. Therefore, the decay heat and cooling boundary condition had no significant effect on temperature distribution characteristics of the pool within the given range of the decay heat and boundary temperature distribution.(c) 2023 Korean Nuclear Society, Published by Elsevier Korea LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Perovskite solar cells approaching 25% PCE using side chain terminated hole transport materials with low concentration in a non-halogenated solvent process
No full textSynchronously achieving high power conversion efficiency (PCE) at low cost is a great challenge for the star hole transport material (HTM) spiro-OMeTAD-based perovskite solar cells (PSCs) because of their expense. Three side-chain modified HTMs, spiro-mF-V, -A, and -P, are designed and synthesized. The incorporation of side chains, such as vinyloxy, allyloxy, and propargyloxy, effectively improves the hole mobility and matches the energy levels with the perovskite layer. All three HTMs show a high PCE of 23.7, 23.80, and 24.85% for spiro-mF-V, -A, and -P using a non-halogenated solvent, such as toluene for eco-friendly PSC fabrication. Furthermore, spiro-mF-V, -A, and -P exhibit good solubility and homogeneous film with smooth surface morphologies in a non-halogenated solvent system. In particular, the obtained PCE values exceed 23.7% at a low concentration in a non-halogenated system, which is one-third that of the spiro-OMeTAD-based PSCs. To the best of the authors' knowledge, it is the highest reported PCE for HTMs using non-halogenated solvents in PSCs. These findings show that the side chain engineering technique can produce novel HTMs for low-cost, environmentally friendly solvent processing
Cortical representation of musical pitch in event-related potentials
No full textNeural coding of auditory stimulus frequency is well-documented; however, the cortical signals and perceptual correlates of pitch have not yet been comprehensively investigated. This study examined the temporal patterns of event-related potentials (ERP) in response to single tones of pitch chroma, with an assumption that these patterns would be more prominent in musically-trained individuals than in non-musically-trained individuals. Participants with and without musical training (N = 20) were presented with seven notes on the C major scale (C4, D4, E4, F4, G4, A4, and B4), and whole-brain activities were recorded. A linear regression analysis between the ERP amplitude and the seven notes showed that the ERP amplitude increased or decreased as the frequency of the pitch increased. Remarkably, these linear correlations were anti-symmetric between the hemispheres. Specifically, we found that ERP amplitudes of the left and right frontotemporal areas decreased and increased, respectively, as the pitch frequency increased. Although linear slopes were significant in both groups, the musically-trained group exhibited marginally steeper slope, and their ERP amplitudes were most discriminant for frequency of tone of pitch at earlier latency than in the non-musically-trained group (similar to 460 ms vs similar to 630 ms after stimulus onset). Thus, the ERP amplitudes in frontotemporal areas varied according to the pitch frequency, with the musically-trained participants demonstrating a wider range of amplitudes and inter-hemispheric anti-symmetric patterns. Our findings may provide new insights on cortical processing of musical pitch, revealing anti-symmetric processing of musical pitch between hemispheres, which appears to be more pronounced in musically-trained people
Photosensitive ion channels in layered MXene membranes modified with plasmonic gold nanostars and cellulose nanofibers
No full textArtificial ion channels are in demand for ionotronic devices. Here, the authors use layered MXene membranes modified with plasmonic gold nanostars and cellulose nanofibers to convert a thermal gradient into an ion current for photosensitive ion channeling. Ion channels transduce external stimuli into ion-transport-mediated signaling, which has received considerable attention in diverse fields such as sensors, energy harvesting devices, and desalination membrane. In this work, we present a photosensitive ion channel based on plasmonic gold nanostars (AuNSs) and cellulose nanofibers (CNFs) embedded in layered MXene nanosheets. The MXene/AuNS/CNF (MAC) membrane provides subnanometer-sized ionic pathways for light-sensitive cationic flow. When the MAC nanochannel is exposed to NIR light, a photothermal gradient is formed, which induces directional photothermo-osmotic flow of nanoconfined electrolyte against the thermal gradient and produces a net ionic current. MAC membrane exhibits enhanced photothermal current compared with pristine MXene, which is attributed to the combined photothermal effects of plasmonic AuNSs and MXene and the widened interspacing of the MAC composite via the hydrophilic nanofibrils. The MAC composite membranes are envisioned to be applied in flexible ionic channels with ionogels and light-controlled ionic circuits
Hand gesture recognition with out-of-distribution gesture detection using a soft sensor embedded glove
No full textHand gesture recognition has been applied to many applications, such as sign language translation and virtual reality. Soft sensor embedded gloves have been widely used to collect gesture data for hand gesture recognition. Using a soft sensor embedded glove has an advantage compared to vision-based approaches, because it is less affected by the environment and is not restricted to the angle of camera sensors, especially when it is applied to virtual reality industry. One of the existing challenges in machine learning-based hand gesture recognition is that new gestures, which are not seen in the training stage, are often discovered in the testing stage. In order to overcome this challenge, in this work, a hand gesture recognition model is proposed based on one-dimensional convolutional neural networks (1D CNN) and long short-term memory (LSTM) as well as a clustering method. In particular, a clustering method is used to detect out-of-distribution gestures, which are not contained in the clusters that are consisted of hand gestures used in the training stage. The experiment results validate that the proposed hand gesture recognition model performs better than existing hand gesture recognition methods and a proposed clustering methods detects out-of-distribution gestures with high accuracy
Molecularly engineered linear organic carbonates as practically viable nonflammable electrolytes for safe Li-ion batteries
No full text<jats:p>Concurrent modification of linear carbonates combining alkyl-chain extension and alkoxy substitution enables thermally stable high-performance batteries by decreasing volatility and increasing solvation ability simultaneously.</jats:p>
Design of Topology???Controlled Polyethers toward Robust Cooperative Hydrogen Bonding
No full textTopology control of polymers is critical for determining their physical properties and potential applications; in particular, topologies that incorporate numerous hydrogen bonding (H-bonding) donors and acceptors along the polymer chains considerably influence the formation of different inter- and intramolecular H-bonding motifs. In this study, the high-level control of inter- and intramolecular H-bonding is investigated in topology-controlled poly(glycidoxy carbonyl benzoic acid)s (PGCs). Three types of topology-controlled PGCs (i.e., linear, hyperbranched, and branched cyclic structures having a similar degree of polymerization) are prepared by introducing aromatic carboxylic acids into the corresponding polyglycidols (PGs) via quantitative post-polymerization modification with phthalic anhydride. The obtained three types of PGCs demonstrated the high-level interplay between the inter- and intramolecular H-bonding in polymer chains by exhibiting the pH-dependent self-association properties in the solution state and the strong adhesion properties in the bulk state with high transparency. Interestingly, the dramatically enhanced adhesive property by 2.6-fold is demonstrated by simple mixing of branched cyclic PGC and topology-controlled PGs to promote the cooperative H-bonding between polymer chains. The new class of cooperative H-bonding is anticipated between topology-controlled polymers to contribute to the development of advanced adhesive and the high potential in biological and biomedical applications due to its excellent biocompatibility
????????? ??????????????? ?????? Ti3C2Tx MXene??? ????????? ???????????? ??????
No full textMXene is one of the most fascinating 2D materials owing to its great electrical properties and unique performance. Among various application areas, the performance of organic material adsorption has been highlighted with the growing interest in the biocompatible applications of MXene. Although previous research revealed that the huge surface area of this 2D nanomaterial could lead to superior organic material adsorption performance, surface functional groups were usually controlled by changing the pH, and the MXene was generally produced by HF etchant. In this study, a surface modification method of Ti3C2Tx MXene film was proposed to enhance organic material adsorption by irradiating the pulsed plasma electron beam (EB). Methylene blue (MB)-dispersed DI water was prepared, and pristine MXene was prepared at pH 7. The MB concentration was only reduced by 20% by pristine MXene. However, EB-treated MXene adsorbed about 75% of the MB within 20 min and over 90% within 80 min when the MXene film was ground to powder form. The results showed that the increased surface area and formation of hydrophilic functional groups successfully modified MB adsorption following EB irradiation under optimal processing conditions
Sensitivity analysis of volatile organic compounds to PM2.5 concentrations in a representative industrial city of Korea
No full textThis study aims to analyze the sensitivity of volatile organic compounds (VOCs) to ambient concentrations of fine particles ( PM2.5) in the representative industrial city of Ulsan, Korea. For the calculation of sensitivity coefficients between VOCs and PM2.5 (SVOCs-PM2.5), PM2.5 data were obtained from an air quality monitoring station, and their corresponding 6-h average concentrations of VOCs (alkanes, alkenes, aromatics, and total VOCs) were measured at the Yeongnam intensive air monitoring station. The air monitoring period was divided into the warm-hot season (May???October 2020) and the cold season (November 2020???January 2021). The sensitivity coefficients in the low pollution period of PM2.5 (5 < PM2.5 ??? 15 ??g/m3) were higher and much higher than those in the medium pollution period (15 < PM2.5 ??? 35 ??g/m3) and high pollution period (35 < PM2.5 ??? 50 ??g/m3), respectively. This result indicates that the change ratios of PM2.5 concentrations to the background ( PM2.5 ??? 5 ??g/m3) per unit concentration change of VOCs (particularly alkenes) in the high PM2.5 pollution period were much higher than those in the low pollution period. This also indicates that PM2.5 concentrations above 35 ??g/m3 were more easily affected by the unit concentration change of VOCs (particularly alkenes) than those below 15 ??g/m3. The average sensitivity coefficients during the cold season increased in a range of 23???125% as compared to those during the warm-hot season, except the alkenes-PM2.5 sensitivity with a decrease of 7%. It means that the impact of VOCs (except alkenes) on PM2.5 concentrations was relatively low in the cold season. However, in the cold season, the alkenes might contribute more to PM2.5 formation, particularly over the high pollution period, having PM2.5 > 35 ??g/m3, than other VOC groups. The result of this study can be a basis for establishing PM2.5 management plans in industrial cities with large VOC emissions
TS-Net: A Deep Learning Framework for Automated Assessment of Longitudinal Tumor Volume Changes in an Orthotopic Breast Cancer Model using MRI
No full textMonitoring tumor volume changes in response to therapeutic agents is a critical step in preclinical drug development. Here, an automated magnetic resonance imaging (MRI)-based approach is proposed using a deep learning framework for tracking longitudinal tumor volume changes in an orthotopic breast cancer model treated with chemotherapy. Longitudinal magnetic resonance images are employed to track changes in tumor volume over time, using an untreated group and a doxorubicin-treated group as the dataset to evaluate treatment effects. Our approach, called Tumor Segmentation-Net (TS-Net), involves replacing the encoder of U-Net with a pre-trained ResNet34 to improve performance. The model was trained using a sample size of n=19 from the untreated group and then subsequently assessed on both the untreated group (n=5) and treated group (n=6). The correlation between the tumor volume determined from the ground truth and that obtained from the trained output was strong ( R2 =0.984, slope=0.996). These results can lead to automated three-dimensional visualization of different longitudinal volume changes with and without treatment. Notably, for small tumors with volumes between 2 and 5 mm 3 , the proposed TS-Net demonstrated an average Dice similarity coefficient score of 0.85, indicating the ability to reliably detect early tumors that may often be missed. Our approach offers a promising tool for preclinical evaluation of tumor volume changes and treatment efficacy in animal models