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Abstract Background Dental development assessment is an important factor in dental age estimation and dental maturity evaluation. This study aimed to develop and evaluate the performance of an automated dental development staging system based on Demirjian’s method using deep learning. Methods The study included 5133 anonymous panoramic radiographs obtained from the Department of Pediatric Dentistry database at Seoul National University Dental Hospital between 2020 and 2021. The proposed methodology involves a three-step procedure for dental staging: detection, segmentation, and classification. The panoramic data were randomly divided into training and validating sets (8:2), and YOLOv5, U-Net, and EfficientNet were trained and employed for each stage. The models’ performance, along with the Grad-CAM analysis of EfficientNet, was evaluated. Results The mean average precision (mAP) was 0.995 for detection, and the segmentation achieved an accuracy of 0.978. The classification performance showed F1 scores of 69.23, 80.67, 84.97, and 90.81 for the Incisor, Canine, Premolar, and Molar models, respectively. In the Grad-CAM analysis, the classification model focused on the apical portion of the developing tooth, a crucial feature for staging according to Demirjian’s method. Conclusions These results indicate that the proposed deep learning approach for automated dental staging can serve as a supportive tool for dentists, facilitating rapid and objective dental age estimation and dental maturity evaluation.

Abstract Background The correlation between dental maturity and skeletal maturity has been proposed, but its clinical application remains challenging. Moreover, the varying correlations observed in different studies indicate the necessity for research tailored to specific populations. Aim To compare skeletal maturity in Korean children with advanced and delayed dental maturity using dental maturity percentile. Design Dental panoramic radiographs and cephalometric radiographs were obtained from 5133 and 395 healthy Korean children aged between 4 and 16 years old. Dental maturity was assessed with Demirjian’s method, while skeletal maturity was assessed with the cervical vertebral maturation method. Standard percentile curves were developed through quantile regression. Advanced (93 boys and 110 girls) and delayed (92 boys and 100 girls) dental maturity groups were defined by the 50th percentile. Results The advanced group showed earlier skeletal maturity in multiple cervical stages (CS) in both boys (CS 1, 2, 3, 4, and 6) and girls (CS 1, 3, 4, 5, and 6). Significant differences, as determined by Mann-Whitney U tests, were observed in CS 1 for boys (p = 0.004) and in CS 4 for girls (p = 0.037). High Spearman correlation coefficients between dental maturity and cervical vertebral maturity exceeded 0.826 (p = 0.000) in all groups. Conclusion A correlation between dental and skeletal maturity, as well as advanced skeletal maturity in the advanced dental maturity group, was observed. Using percentile curves to determine dental maturity may aid in assessing skeletal maturity, with potential applications in orthodontic diagnosis and treatment planning.

In the rapidly advancing field of electronics, there is a growing demand for devices to be miniaturized with high-resolution patterns and compact, straightforward configurations, all while maintaining cost competitiveness. Precision patterning of conductive nano ink based on inexpensive metals offers an effective solution. This technique has proven compatibility with numerous integrated electronics. However, conventional patterning techniques face difficulties achieving high resolution, uniform thickness, and compatibility with environments prone to oxidation. Here, we optimize the reverse offset printing process and its ink formulation for green manufacturing of high-quality, high-resolution conductive micropatterns. The oleate ligand on the surface of Cu nanoparticles (CuNPs) is replaced by polyvinylpyrrolidone, which is more suitable for the steric stabilization of CuNPs in eco-friendly, polar solvent. Then, in consideration of the reverse offset printing mechanism, solvents and additives are evaluated to prepare a reverse offset printable ink. By examining the change in printability according to the composition and process parameters, we determine the printable composition range and process conditions. High-quality CuNP micropatterns with a fine line width of 10 μm, narrow spacing, sharp edge definition, and high uniformity are achieved. Finally, the reverse offset printed CuNP micropatterns are successfully implemented in thermistor microarrays as a potential application.

Abstract Background Permanent first molars with severe dental caries, developmental defects, or involved in oral pathologies are at risk of poor prognosis in children. Accordingly, using the third molar to replace the first molar can be a good treatment option when third molar agenesis is predicted early. Thus, this retrospective cohort study aimed to develop criteria for early detection of mandibular third molar (L8) agenesis based on the developmental stages of mandibular canine (L3), first premolar (L4), second premolar (L5), and second molar (L7). Method Overall, 1,044 and 919 panoramic radiographs of 343 males and 317 females, respectively, taken between the ages of 6 and 12 years were included. All developmental stages of L3, L4, L5, L7, and L8 were analyzed based on the dental age, as suggested by Demirjian et al. The independent t-test was used to assess age differences between males and females. The rank correlation coefficients were examined using Kendall’s tau with bootstrap analysis and Bonferroni’s correction to confirm the teeth showing developmental stages most similar to those of L8s. Finally, a survival analysis was performed to determine the criteria for the early diagnosis of mandibular third molar agenesis. Results Some age differences were found in dental developmental stages between males and females. Correlation coefficients between all stages of L3, L4, L5, and L7 and L8 were high. In particular, the correlation coefficient between L7 and L8 was the highest, whereas that between L3 and L8 was the lowest. Conclusion If at least two of the following criteria (F stage of L3, F stage of L4, F stage of L5, and E stage of L7) are met in the absence of L8 crypt, agenesis of L8 can be confirmed.

This paper proposes a data-driven state feedback controller that enables reference tracking for nonlinear discrete-time systems. The controller is designed based on the identified inverse model of the system and a given reference model, assuming that the identification of the inverse model is carried out using only the system’s state/input measurements. When its results are provided, we present conditions that guarantee a certain level of reference tracking performance, regardless of the identification method employed for the inverse model. Specifically, when Gaussian process regression (GPR) is used as the identification method, we propose sufficient conditions for the required data by applying some lemmas related to identification errors to the aforementioned conditions, ensuring that the Model Reference-GPR (MR-GPR) controller can guarantee a certain level of reference tracking performance. Finally, an example is provided to demonstrate the effectiveness of the MR-GPR controller.

This study conducted laboratory tests and field surveys to understand the plasticizer contamination characteristics on the surface of PVC flooring materials used indoors, and discussed the risk of exposure of plasticizers to infants indoors. A lab experiment was conducted to measure the bleed-out of DEHP on PVC sheet surfaces. As a result of the bleed-out, the amount of DEHP on the specimen surfaces was 432 to 880 [ug/m2]. The present study showed that plasticizers such as DEHP contained in the PVC sheet accumulate a significant amount of DEHP on the surface of the PVC sheet even if a material such as house dust is not present on the surface of the PVC sheet. In addition, this study found that even if the dust accumulated on the PVC floor surface was vacuumed, it was difficult to completely remove the DEHP accumulated on the floor surface. The field surveys showed that the average concentration of DEHP on the floor surface in Korean and Japanese house were 356 and 608 ug/m2 respectively. Since infants have behavioral characteristics of crawling, sitting, and lying on the floor, they have more opportunities to directly contact the floor than adults.

Abstract The understanding and engineering of the plasmon-exciton coupling are necessary to control the innovative optoelectronic device platform. In this study, we investigated the intertwined mechanism of each plasmon-exciton couplings in monolayer molybdenum disulfide (MoS2) and plasmonic hybrid structure. The results of absorption, simulation, electrostatics, and emission spectra show that interaction between photoexcited carrier and exciton modes are successfully coupled by energy transfer and exciton recombination processes. Especially, neutral exciton, trion, and biexciton can be selectively enhanced by designing the plasmonic hybrid platform. All of these results imply that there is another degree of freedom to control the individual enhancement of each exciton mode in the development of nano optoelectronic devices.

Aging leads to time-dependent functional decline of all major organs. In particular, the aging brain is prone to cognitive decline and several neurodegenerative diseases. Various studies have attempted to understand the aging process and underlying molecular mechanisms by monitoring changes in gene expression in the aging mouse brain using high-throughput sequencing techniques. However, the effect of microRNA (miRNA) on the post-transcriptional regulation of gene expression has not yet been comprehensively investigated. In this study, we performed global analysis of mRNA and miRNA expression simultaneously in the hypothalamus and hippocampus of young and aged mice. We identified aging-dependent differentially expressed genes, most of which were specific either to the hypothalamus or hippocampus. However, genes related to immune response-related pathways were enriched in upregulated differentially expressed genes, whereas genes related to metabolism-related pathways were enriched in downregulated differentially expressed genes in both regions of the aging brain. Furthermore, we identified many differentially expressed miRNAs, including three that were upregulated and three that were downregulated in both the hypothalamus and hippocampus. The two downregulated miRNAs, miR-322-3p, miR-542-3p, and the upregulated protein-encoding coding gene C4b form a regulatory network involved in complement and coagulation cascade pathways in the hypothalamus and hippocampus of the aging brain. These results advance our understanding of the miRNA-mediated gene regulatory network and its influence on signaling pathways in the hypothalamus and hippocampus of the aging mouse brain.

Abstract We investigate conducting characteristics of biochar derived from the pyrolysis of a paper at terahertz frequencies. Paper is annealed under temperatures ranging from 600 to 1000 °C to modify structural and electrical properties. We experimentally observe that the terahertz conductivity increases above 102 S/m as the annealing temperature increases up to 800 °C. From structural characterization using energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, we confirm that more graphitic biochars are produced in high annealing temperature, in agreement with the improvement of terahertz conductivity. Our results show that biochar can be a highly promising candidate to be used in paper-based devices operating at terahertz frequencies.

Large-scale serial production industries such as automotive and aerospace have focused on reducing weight to improve fuel economy, and many parts are manufactured from various aluminum alloys. Due to the ease of recycling of aluminum alloys, research on remanufacturing has not been very active. On the other hand, laser cladding on aluminum alloys is a surface modification and repair process that deposits a thin layer on a substrate using a laser beam whose output can be easily controlled. This makes it suitable for remanufacturing processes where thin layers of damaged parts can be easily repaired, and helps to save energy. In this study, laser cladding was performed using aluminum alloy powder (Al-102) containing Si to improve the surface hardness of Al 4047 used as automotive engine parts and repair damaged parts. Several experimental studies have been conducted regarding the effect on laser power and powder flow rate. In addition, the improvement effect through the hardness analysis of the cladded layer and the change of the microstructure through the cross-section analysis of the clad part are discussed. Finally, the experimental conditions analyzed in this study suggest a suitability for the actual remanufacturing process through multi-pass cladding through overlapping.

Recently, Korea has upgraded the luminance standard of classrooms and started to introduce the air-conditioning system in order to enhance pleasantness of the learning environment. In addition, as use of auxiliary equipment, such as TV, VTR and computer, is increasing and due to school meals, energy consumption is increasing in school facilities. Despite the increase of energy consumption of school facilities, however, it is difficult to find actual data on energy consumption. Therefore, in this study, the actual conditions of energy consumption are researched, and the relation between the facility area, the number of classes and students, and the cooling and heating facilities is analyzed. And then, the basic data required for energy-saving strategies at school facilities are prepared. In conclusion, the energy consumption of the surveyed schools is increasing. The total annual energy consumption of each school is estimated to be 400–1750[MWh/yr], which varies between schools depending on the scale. The electric power consumption accounted for approx. 82% of the total energy consumption of the surveyed schools, and LNG and kerosene accounted for 14% and 4%, respectively. The schools using fans for cooling had significantly lower energy consumption than the schools with Electric Heat Pump(EHP). The annual energy consumption per unit area of the surveyed schools is approx. 67–240[kWh/m2/yr], and the annual average energy consumption per unit area is 133[kWh/m2/yr]. However, there is no significant difference in energy consumption per student. These results can be caused by various reasons, but are especially related with the size of school and the number of classes. Keywords: Middle schools, Buildings, Energy, Educational facilities, Energy consumption

This study measured ventilation volumes and particle concentrations in indoor environments with open windows and doors. In addition, the effect of the airflow mode of the air conditioner on the ventilation volume and indoor particle concentration variations was also measured. The ventilation fan could only provide approximately 43% of the ventilation volume during the design phase. The amount of ventilation differed depending on the opening area in windows and doors. The ventilation volume was increased by opening multiple windows or doors, even when the area of the opening was the same. No significant change in the ventilation rate was observed, although the air conditioner was expected to promote the ventilation rate in the room when set on blow mode. It was confirmed that both 0.3 and 1 μm particles could enter through the gaps around the windows and doors. Although most of the 5 μm particles were from the outdoor air, when the air conditioner was operated in airflow mode, the removal of 5 μm particles was performed by the air conditioner filter. The use of medium-performance or HEPA filters is expected to remove smaller particulates.

In this study, the indoor air quality and thermal environment of a university facility were analyzed when an air conditioner was operated and natural ventilation was provided; the most effective natural ventilation method was also evaluated. The research conditions were established by adjusting the temperature of the air conditioner, and frequency of window openings every hour. The area around the windows that is open for natural ventilation was easily affected by outdoor air temperature and humidity. However, since the air conditioner was operating, there was only a brief period during which the environment was uncomfortable. Therefore, the participants in the questionnaire survey expressed neutrality or slight satisfaction for the thermal environment of the entire space. Setting the room temperature to 25 °C in summer was highly comfortable and generated a satisfactory indoor thermal environment. When the room temperature was set to 20 °C in winter, the thermal comfort level was higher than in the other conditions. Providing natural ventilation for 5 min every 30 min was determined to be effective in maintaining an indoor CO2 concentration of 1000 ppm or less. Facilitating natural ventilation for 10 min every 60 min allowed the entry of a large amount of fresh air; however, due to the extended period in which the windows and doors were closed, there were instances when the indoor CO2 concentration exceeded 1000 ppm. Therefore, providing frequent natural ventilation with short time intervals is effective for improving indoor air quality.

Objective To investigate if the extent of lumbar segmental motion is correlated with the recovery process in the form of pain intensity in patients with acute single level lumbar disc herniation (LDH). Methods A retrospective review of medical records was performed on patients presented with acute low back pain from January 2011 to December 2017. With prerequisites of undergoing both lumbar spine magnetic resonance imaging and functional radiography, patients with etiologies other than single level LDH were excluded. A total of 46 patients were selected, including 27 patients with disc herniation at L4-5 level and 19 patients at L5-S1 level. Pearson correlation analysis of pain intensity against segmental range of motion (sROM) and percentage of sROM of each lumbar segment was performed at the initial evaluation point and follow-ups. Results Serial documentation of pain intensity and functional radiography exhibited an inverse correlation between changes in visual analogue scale (VAS) and sROM in single level LDH at L4-5 level (r=-0.69, p

Following the Paris Agreement in 2015, the worldwide focus on global warming countermeasures has intensified. The Japanese government has declared its aim at achieving carbon neutrality by 2050. The concept of zero-energy buildings (ZEBs) is based on measures to reduce energy consumption in buildings, the prospects of which are gradually increasing. This study investigated the annual primary energy consumption; as well as evaluated, renewed, and renovated buildings that had a solar power generation system, and utilized solar and geothermal heat. It further examines the prospects of hydrogen production from on-site surplus electricity and the use of hydrogen fuel cells. A considerable difference was observed between the actual energy consumption (213 MJ/m2), and the energy consumption estimated using an energy simulation program (386 MJ/m2). Considerable savings of energy were achieved when evaluated based on the actual annual primary energy consumption of a building. The building attained a near net zero-energy consumption considering the power generated from the photovoltaic system. The study showed potential energy savings in the building by producing hydrogen, using surplus electricity from on-site power generation, and introducing hydrogen fuel cells. It is projected that a building’s energy consumption will be lowered by employing the electricity generated by the hydrogen fuel cell for standby power, water heating, and regenerating heat from the desiccant system.

Colorectal cancer: Potential treatment for drug-resistant cases A recently identified small molecule shows promise for tackling resistance to a leading colorectal cancer drug. Three proteins that are over-expressed in colorectal cancer are epidermal growth factor receptor (EGFR), RAS and β-catenin. These proteins and their interconnected signaling pathways are therefore important therapeutic targets. EGFR is the target of the drug cetuximab, but many patients are resistant to this drug attributed to mutations in a gene that influences the signaling pathways of the three key proteins. Kang-Yell Choi at Yonsei University in Seoul, South Korea, and co-workers trialed a novel molecular drug on human colorectal cancer tissues and on mice. They confirmed that the new drug leads to reduced EGFR levels by degrading RAS and β-catenin and therefore suppresses the growth of colorectal cancer cells in samples with or without the resistant mutations.

This study investigated the pollution caused by unregulated chemical substances in Korean residential environments. A TA tube was used for indoor air collection, and Gas Chromatography–Mass Spectrometry was used for the analysis of chemical substances. According to the results of this study, 13 substances out of the 16 analyzed chemicals were detected and, among them, the concentrations of phenol, α-pinene, and limonene within the indoor air were high. The average concentration of phenol was 32.7 µg/m3. α-pinene and limonene were detected, of which the highest concentrations were as 598.2 µg/m3 and 652.5 µg/m3, respectively. The maximum concentrations of these three substances exceeded the levels of the lowest concentration of interest. Notably, α-pinene and limonene were released from the wood itself. Wood has been widely used indoors as a natural building material and as furniture. Therefore, it was considered that this was the reason for the high the concentrations of the two substances in indoor air. However, we do not argue that the usage of wood should be reduced because of the results obtained in this study. Instead, we sµggest that it is important to reduce the emissions of α-pinene and limonene throµgh the processing of the wood, extending its drying period, and determining the most appropriate time of use.

Palatal myoclonus (PM) is a rare disease that may induce dysphagia. Since dysphagia related to PM is unique and is characterized by myoclonic movements of the involved muscles, specific treatments are needed for rehabilitation. However, no study has investigated the treatment effectiveness for this condition. Therefore, the aim of this case report was to describe the benefit of combining behavioral treatment with valproic acid administration in patients with dysphagia triggered by PM. The two cases were treated with combined treatment. The outcomes evaluated by videofluoroscopic swallowing studies before and after the treatment showed significant decreases in myoclonic movements and improved swallowing function. We conclude that the combined treatment was effective against dysphagia related to PM.

We aimed to increase the processing area of the roll-to-roll (R2R) nanoimprint lithography (NIL) process for high productivity, using a long roller. It is common for a long roller to have bending deformation, geometric errors and misalignment. This causes the non-uniformity of contact pressure between the rollers, which leads to defects such as non-uniform patterning. The non-uniformity of the contact pressure of the conventional R2R NIL system was investigated through finite element (FE) analysis and experiments in the conventional system. To solve the problem, a new large-area R2R NIL uniform pressing system with five multi-backup rollers was proposed and manufactured instead of the conventional system. As a preliminary experiment, the possibility of uniform contact pressure was confirmed by using only the pressure at both ends and one backup roller in the center. A more even contact pressure was achieved by using all five backup rollers and applying an appropriate pushing force to each backup roller. Machine learning techniques were applied to find the optimal combination of the pushing forces. In the conventional pressing process, it was confirmed that pressure deviation of the contact area occurred at a level of 44%; when the improved system was applied, pressure deviation dropped to 5%.

Distributed energy resource (DER) has been widely deployed, and distributed generation (DG) can complement the distribution system. Favorable DG deployment provides the grid-connected microgrid (MG) with stable voltage and reduces emission and power generation costs. DGs are considered distributed feeders, and MG is required to be operated under the optimal state. Reconfiguration is a practical approach to optimizing resource allocation. The optimal global solution is obtained via optimization algorithms. In this paper, three objectives are defined, namely, minimization of economic cost (ECC), emission cost (EMC), and voltage deviation (VD). Consequently, a fuzzy moth-flame optimization (FMFO) algorithm is proposed to coordinate the interests of multiple objectives. Moreover, the simulation is conducted based on the standard IEEE 33-bus radial distribution system (RDS), under which the impact of deployment of various DG type and quantity on the MG is explored. In particular, diverse DG combinations are tried under the increasing power demand, and a high-stable voltage strategy is proposed to meet the specific demands. The simulation results reveal that: (1) the DG type has a significant impact on ECC and EMC; (2) penetration level of DG shows a positive-like relationship with the MG stability; and (3) the proposed FMFO algorithm exhibits an efficient performance in convergence.

Background and Purpose We aimed to investigate the usefulness of combining transcranial magnetic stimulation (TMS) and diffusion tensor tractography (DTT) to evaluate corticospinal tract (CST) integrity and subsequently predict ambulatory function after middle cerebral artery (MCA) stroke. Methods Forty-three patients with first MCA stroke underwent TMS and DTT to evaluate CST integrity. Patients were classified into four groups according to the presence of motor-evoked potentials (MEPs) obtained from the tibialis anterior muscle and CST integrity. Motor impairment and functional status were assessed using the Fugl-Meyer Assessment, Functional Ambulation Category, and Korean modified Barthel Index, both at the time of admission and after 4 weeks of rehabilitation. Results Patients with the presence of both measurable MEPs and a preserved CST showed better motor recovery and ambulatory function than other groups at the 4-week follow-up. Intact CSTs were not visualized in patients without detectable MEPs. Among the patients displaying MEPs, those with preserved CSTs showed better recovery of paretic lower extremities. Conclusions Combined assessment using TMS and DTT to evaluate CST integrity confers advantages in predicting motor and ambulation recovery in patients with MCA stroke.

Twisted bilayer graphene (tBLG) is two stacked single graphene sheets rotated at a specific angle. The twist angle plays an important role in the physical properties of the tBLG. In this study, we analyzed the interaction distance between two graphene layers in tBLG using Raman spectroscopy and atomic force microscopy. To confirm the interaction of the upper and bottom graphenes in the tBLG, we prepared two tBLGs with twist angles of 5° and 24°. The interlayer distance was controlled by depositing a gold bar between the two graphene layers. We found that the decoupling interlayer distance of the tBLG was different depending on the twist angle (0.74 nm for 5° and 1.66 nm for 24°). This indicates that the interaction between two graphene layers is strongly coupled with small twist angle, as expected.

This study aimed to investigate the colorimetric properties of newly developed composites for dental trauma splints using various staining solutions during the clinical splinting period. The clear shades of G-Fix (GF), Ortho Connect Flow (OC), Light Fix (LF), and Filtek Z350XT (FZ) were fabricated into 96 disk-shaped specimens. Specimens from each composite group were stored in distilled water, coffee, tea, and red wine solutions at 37ºC. CIE values were measured using a spectrophotometer at 24 h after specimen preparation and at 1 day, 1 week, 2 weeks, 3 weeks, and 4 weeks after storage in each solution. Color differences and translucency parameters were calculated using the initial and measured values. Within the experiment period, the color differences of GF, OC, and LF compared to the initial measurement were smaller than that for FZ for all staining solutions except distilled water. There were no significant color differences between the GF, OC, and LF groups. [ABSTRACT FROM AUTHOR]