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Sea turtles exhibit high migratory rates and occupy a broad range of habitats, which in turn makes monitoring these taxa challenging. Applying deep learning (DL) models to vast image datasets collected from citizen science programs can offer promising solutions to overcome the challenge of monitoring the wide habitats of wildlife, particularly sea turtles. Among DL models, object detection models, such as the You Only Look Once (YOLO) series, have been extensively employed for wildlife classification. Despite their successful application in this domain, detecting objects in images with complex backgrounds, including underwater environments, remains a significant challenge. Recently, instance segmentation models have been developed to address this issue by providing more accurate classification of complex images compared to traditional object detection models. This study compared the performance of two state-of-the-art DL methods namely; the object detection model (YOLOv5) and instance segmentation model (YOLOv5-seg), to detect and classify sea turtles. The images were collected from iNaturalist and Google and then divided into 64% for training, 16% for validation, and 20% for test sets. Model performance during and after finishing training was evaluated by loss functions and various indexes, respectively. Based on loss functions, YOLOv5-seg demonstrated a lower error rate in detecting rather than classifying sea turtles than the YOLOv5. According to mean Average Precision (mAP) values, which reflect precision and recall, the YOLOv5-seg model showed superior performance than YOLOv5. The mAP0.5 and mAP0.5:0.95 for the YOLOv5 model were 0.885 and 0.795, respectively, whereas for the YOLOv5-seg, these values were 0.918 and 0.831, respectively. In particular, based on the loss functions and classification results, the YOLOv5-seg showed improved performance for detecting rather than classifying sea turtles compared to the YOLOv5. The results of this study may help improve sea turtle monitoring in the future. [ABSTRACT FROM AUTHOR]

Simple Summary: Sialocele-related concurrent diseases or factors in dogs are not well documented, and occasionally, dogs with sialocele have been found to have concurrent hypercortisolism (HC) or a history of long-term glucocorticoid (GC) treatment. In this retrospective case–control study, we investigated the association between HC, long-term GC treatment, and the diagnosis of sialocele in dogs. The occurrence of sialocele was higher in dogs with HC and those receiving long-term GC treatment, that is, treatment lasting for more than 5 months. This suggests that endogenous and exogenous GCs may influence sialocele formation. Therefore, we recommend regular monitoring for sialocele occurrence in dogs with HC or those receiving long-term GC treatment. Dogs with sialocele often have concurrent hypercortisolism or are receiving long-term glucocorticoid treatment. However, their association has not been investigated. This retrospective matched case–control study investigated the association between hypercortisolism, long-term glucocorticoid treatment, and sialocele in dogs. We retrospectively reviewed the records from 1 January 2018 to 31 December 2022. Records of 19 dogs diagnosed with sialocele were investigated for hypercortisolism and long-term glucocorticoid treatment. Two age- and breed-matched controls for each sialocele dog (38 dogs) were investigated for the same concurrent diseases. Logistic regression analysis was used. The odds of sialocele in dogs with hypercortisolism were 15.56 times those of dogs without hypercortisolism (p = 0.02; 95% CI: 1.54–156.79). The odds of sialocele in dogs with long-term glucocorticoid treatment (median, 8 months; range, 5–13) were 7.78 times those of dogs without long-term glucocorticoid treatment (p = 0.03; 95% CI: 1.23–49.40). No associations were found between age, sex, body weight, and the presence of sialocele. The results indicate that sialocele was significantly associated with hypercortisolism and long-term glucocorticoid treatment in dogs. Therefore, dogs with hypercortisolism or receiving long-term glucocorticoid therapy should be screened for possible sialocele. Additionally, dogs with sialocele should be identified for concurrent hypercortisolism and prolonged glucocorticoid exposure. [ABSTRACT FROM AUTHOR]

Simple Summary: Most parrot species are threatened with extinction because of habitat loss and commercial trade. Parrot conservation is vital because parrots play an important role in the ecosystem. The Amazon parrots are one of the most endangered parrot species. Monitoring their wild population and global trade is essential for their conservation. However, this is becoming more challenging because it requires manual analysis of large-scale image data. Furthermore, the morphological identification of the Amazon parrots can be difficult because they have similar morphological features. Deep learning-based object detection models are useful tools for monitoring wild populations and global trade. In this study, 26 Amazon parrot species were classified using eight object detection models. The object detection model, which showed the highest accuracy, classified the 26 Amazon parrot species at 90.7% on average. The continuous development of deep learning models for classifying Amazon parrots might help to improve the ability to monitor their wild populations and global trade. Parrots play a crucial role in the ecosystem by performing various roles, such as consuming the reproductive structures of plants and dispersing plant seeds. However, most are threatened because of habitat loss and commercial trade. Amazon parrots are one of the most traded and illegally traded parrots. Therefore, monitoring their wild populations and global trade is crucial for their conservation. However, monitoring wild populations is becoming more challenging because the manual analysis of large-scale datasets of images obtained from camera trap methods is labor-intensive and time consuming. Monitoring the wildlife trade is difficult because of the large quantities of wildlife trade. Amazon parrots can be difficult to identify because of their morphological similarity. Object detection models have been widely used for automatic and accurate species classification. In this study, to classify 26 Amazon parrot species, 8 Single Shot MultiBox Detector models were assessed. Among the eight models, the DenseNet121 model showed the highest mean average precision at 88.9%. This model classified the 26 Amazon parrot species at 90.7% on average. Continuous improvement of deep learning models classifying Amazon parrots may support monitoring wild populations and the global trade of these species. [ABSTRACT FROM AUTHOR]

In this study, we suggest a method to amplify spin waves (SWs) in antiferromagnets (AFMs). By introducing a non-uniform Dzyaloshinskii–Moriya (DM) interaction, the potential barrier forms a resonant cavity. SWs with an opposite chirality undergo scattering and are resonantly amplified at a phase-matching condition. The calculation is performed in the insulating AFMs where the electric-field-induced DM interaction and pseudo-dipole anisotropy broaden the parabolic-like SW band for multiple resonant modes. Using a transfer matrix method, we also show numerically that scattering between SWs contributes significantly to the SW amplification. Since the electric field selectively amplifies the SWs with resonant frequencies, the proposed device works as an SW transistor and rectifier. This finding will contribute to insulating AFM-based magnon devices where Joule heating is, in principle, avoided. [ABSTRACT FROM AUTHOR]

Continuous-wave (CW) terahertz (THz) imaging with a horn antenna is proposed to enhance the spatial resolution of a THz imaging system. The attached waveguide that is smaller than the wavelength can easily increase the spatial resolution, and the optimized horn flare can significantly increase the transmission power. Consequentially, transmission THz images of a phantom obtained by the amplitude signal using a 0.2 THz wave reveal that the spatial resolution is achieved up to 500 μm. Also, the transmitted power is increased up to 6 times higher compared to the pinhole aperture. The feasibility of CW THz imaging with a horn antenna is demonstrated by the inspection of the organic samples inside food resulting in a relatively high sensitivity for soft organic samples compared with the sensitivity of X-ray imaging to this kind of samples. [ABSTRACT FROM AUTHOR]

The fabrication of two-dimensional terahertz photonic crystals using wet chemical etching of high-resistivity silicon is described. Wet-etched photonic crystals with a sloped sidewall were fabricated in 16 × 10 square lattices with a period of 1430 μm and a height of 150 μm, and were bonded between two parallel Au-coated silicon wafers for tight confinement in the vertical direction. The formation of a photonic band gap at a frequency of about 0.1 THz with a width of 14 GHz is demonstrated by the experimental results and the numerical simulations of the transmission frequency spectrum for the transverse magnetic mode. [ABSTRACT FROM AUTHOR]

The effects of the energy spread of secondary electrons are theoretically investigated for a dc-biased single-surface multipactor. In our previous publication [S. G. Jeon et al., Phys. Plasmas 16, 073101 (2009)], we obtained the conditions for the phase lock of an electron bunch, assuming zero velocity spread of the secondary electrons. In this work, we extended our previous theory to derive a quadratic map, by which the stability and bifurcation of the electron bunch can be systematically investigated. For the study of the energy spread of the secondary electrons, a randomized term was added to this map. The modified map then showed significant smearing-out of the bifurcated branches. The theoretical results were verified by particle-in-cell simulations, which showed good agreement in wide parameter ranges for both cases of monoenergetic and energy-spread secondary electrons. [ABSTRACT FROM AUTHOR]

Abstract: A terahertz (THz) Smith–Purcell (SP) backward-wave oscillator with an inverse wet-etched grating based on silicon has been proposed to enhance radiation intensity. This grating strengthens the interactions between an electron beam and the evanescent wave due to the adjacent surface structure between gratings that improves the magnitude of the electric field up to 1.7 times compared to the conventional rectangular gratings. A two-dimensional particle-in-cell (PIC) simulation shows that the radiated power is increased up to 2.3 times higher at the radiated frequency of 0.66 THz for an electron-beam energy of 30 keV. [ABSTRACT FROM AUTHOR]

Daphnia galeata is an important plankton in aquatic ecosystems. As a widely distributed species, D. galeata has been found throughout the Holarctic region. Understanding the genetic diversity and evolution of D. galeata requires the accumulation of genetic information from different locations. Even though the mitochondrial genome (mitogenome) sequence of D. galeata has already been reported, little is known about the evolution of its mitochondrial control region. In this study, D. galeata samples were collected from the Han River on the Korean Peninsula and its partial nd2 gene was sequenced for haplotype network analysis. This analysis showed that four clades of D. galeata were present in the Holarctic region. Moreover, the D. galeata examined in this study belonged to clade D and was specific to South Korea. The mitogenome of D. galeata from the Han River showed similar gene content and structure compared to sequences reported from Japan. Furthermore, the structure of control region of the Han River was similar to those of Japanese clones and differed substantially from European clone. Finally, a phylogenetic analysis based on the amino acid sequences of 13 protein-coding genes (PCGs) indicated that D. galeata from the Han River formed a cluster with clones collected from Lakes Kasumigaura, Shirakaba, and Kizaki in Japan. The differences in control region structure and stem and loop structure reflect the different evolutionary directions of the mitogenomes from Asian and European clones. These findings improve our understanding of the mitogenome structure and genetic diversity of D. galeata. [ABSTRACT FROM AUTHOR]

The crystalline TiO2 nanoparticles were prepared by γ-ray irradiation with the dose of 30 kGy and dose rate of 3.9 kGy/hr at room temperature under atmospheric pressure. X-ray photoelectron spectroscopy (XPS) was used to investigate the chemical composition of TiO2. By x-ray diffraction (XRD) analysis, it was revealed that the prepared particles were the anatase or rutile phase of TiO2 according to the preparation conditions. Scanning electron microscope (SEM) was used to characterize the shape and size of the particles. [ABSTRACT FROM AUTHOR]

Among catechin compounds abundant mainly in green tea, (-)epigallocatechin gallate (EGCG) has antioxidative and anticarcinogenic properties. Korean green tea (Bosung, Chonnam) was used as a feed sample. The separation was done by a C18 reversed-phase preparative column (22×250 mm) with mobile phases of 0.1% acetic acid in water, acetonitrile, methanol, and ethyl acetate considered. The injection volume and the flow rate of mobile phase were fixed at 400 μL and 16 mL/min, respectively. To purify EGCG preparatively, the effluent was collected from the column outlet and concentrated, and analyzed by analytical column (3.9×300 mm). From the experimental results, the optimum mobile phase condition for separating EGCG from Korean green tea was 0.1% acetic acid in water/acetonitrile/methanol/ethyl acetate (80/16/1/3 vol.%). In the experimental condition, 0.6 mg of EGCG was obtained purely. [ABSTRACT FROM AUTHOR]

To isolate epigallocatechin gallate (EGCG) of catechin compounds from Korean green tea (Bosung, Chonnam), a C18 reversed-phase preparative column (250×22 mm) packed with packings of three different sizes (15, 40–63, and 150 μm) was used. The sample extracted with water was partitioned with chloroform and ethyl acetate to remove the impurities including caffeine. The mobile phases in this experiment were composed of 0.1% acetic acid in water, acetonitrile, methanol and ethyl acetate. The injection volume was fixed at 400 μl and the flow rate was increased as the particle size becomes larger. The isolation of EGCG with particle size was compared at a preparative scale and the feasibility of separation of EGCG at larger particle sizes was confirmed. The optimum mobile phase composition for separating EGCG was experimentally obtained at the particle sizes of 15 and 40–63 μm in the isocratic mode, but EGCG was not purely separated at the particle size of 150 μm. [Copyright &y& Elsevier]

Cacatua alba, Cacatua galerita, and Cacatua goffiniana are parrots of the family Cacatuidae. Wild populations of these species are declining with C. alba listed by the International Union for the Conservation of Nature and Natural Resources (IUCN) as Endangered. In this study, complete mitogenomes were sequenced for a comparative analysis among the Cacatua species, and a detailed analysis of the control region. Mitogenome lengths of C. alba,C. galerita, and C. goffiniana were 18,894, 18,900, and 19,084 bp, respectively. They included 13 protein coding genes, two ribosomal RNA genes, 24 transfer RNA genes, three degenerated genes, and two control regions. Ten conserved motifs were found in three domains within each of the two control regions. For an evolution of duplicated control regions of Cacatua, domain I and the 3′ end of domain III experienced an independent evolution, while domain II and most of the regions of domain III was subjected to a concerted evolution. Based on a phylogenetic analysis of 37 mitochondrial genes, the genus Cacatua formed a well-supported, monophyletic, crown group within the Cacatuidae. Molecular dating results showed that Cacatua diverged from other genera of Cacatuinae in the middle of Miocene. [ABSTRACT FROM AUTHOR]

Abstract Seafood is critically important to the human's diet worldwide because of its common and rich nutrients. However, seafood mislabeling may cause harms to consumers in terms of economic loss and health. DNA barcoding has gained its popularity in seafood authentication. Although South Korea is one of the biggest seafood markets in the world, there is still no large scale study using DNA barcoding to detect seafood mislabeling in the country. In this study, partial COI gene was used to investigate seafood mislabeling in South Korea. COI fragments of 157 food samples and 88 reference samples we collected and analyzed. Of 157 food samples, we found 12 mislabeling cases, including four species of name mislabeling and two species of origin mislabeling. Overall, mislabeling rate detected in this study is 7.6%. Our results provide fundamental for food safety management as well as future study on seafood authentication. Highlights • Seafood mislabeling may cause harms to consumers in terms of economic loss and health. • This study presents a large scale examination of seafood mislabeling in South Korea. • Mislabeling rate detected in South Korea is comparatively low. [ABSTRACT FROM AUTHOR]

Layered nanomaterials with in‐plane anisotropy exhibit unique orientation‐dependent responses to external stimuli, enabling the development of novel devices with additional degrees of freedom. In particular, their anisotropic optical properties enable ultrafast nanophotonic modulators to be controlled by light polarization. However, achieving high controllability is still challenging due to incomplete optical anisotropy in most materials. Here, this work presents a completely anisotropic, ultrafast optical modulation in zirconium pentatelluride (ZrTe5), a layered nanomaterial that has recently attracted renewed attention. The transient absorption (TA) microscopy reveals anisotropic ultrafast picosecond optical modulation in a broad range of 1.2–2.2 eV. In particular, at a certain photon‐energy of 1.62 eV, complete on/off switching with a near‐unity degree of anisotropy is achieved solely by changing the light polarization, suggesting that ZrTe5 is a promising material for polarization‐selective high‐speed optical modulators. The theoretical analysis of the transition dipole moments attributes this sharp anisotropy to strongly polarization‐dependent excited‐state absorption. Furthermore, this work directly observes direction‐dependent photocarrier transport using scanning TA microscopy. It yields the anisotropic diffusivity, mobility, and diffusion lengths of the photocarriers, which are essential parameters for designing devices. Therefore, this work provides a comprehensive understanding of the anisotropic optical characteristics of ZrTe5 on ultrafast timescales. [ABSTRACT FROM AUTHOR]

Abstract: A randomized, double-blind, and placebo-controlled clinical study was performed to evaluate the antioxidant effects of fermented sea tangle (FST) on healthy volunteers with high levels of γ-glutamyltransferse (γ-GT). Forty-eight participants were divided into a placebo group and an FST group that received FST (1.5g/day) for 4weeks. Serum γ-GT, malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) activities were determined before and after the trial. Administering FST significantly decreased serum levels of γ-GT and MDA. Additionally, SOD and CAT activities were significantly augmented compared to those in the placebo group after 4weeks, but no significant alteration was observed in GPx activity compared to that in the placebo group. Our findings indicate that FST enhanced the antioxidant defense system in a healthy population and may be useful as a functional food ingredient. [Copyright &y& Elsevier]

We studied the influences of wide energy spectrum and emission angle of secondary electrons on electron bunching from a dc-biased single surface multipactor. In our previous study of the same system, an ideally narrow energy spread of secondary electrons without emission angle was used in the analysis of the electron trajectory [M. S. Hur, J.-I. Kim, G.-J. Kim, and S.-G. Jeon, Phys. Plasmas 18, 033103 (2011) and S.-G. Jeon, J.-I. Kim, S.-T. Han, S.-S. Jung, and J. U. Kim, Phys. Plasmas 16, 073101 (2009)]. In this paper, we investigated the cases with realistic energy spectrum, which is featured by a wide energy spread and significant emission angle. To theoretically approach the matter of emission angle, we employed a concept of effective longitudinal velocity distribution. The theoretical results are verified by particle-in-cell (PIC) simulations. We also studied the electron bunching from a copper by PIC simulations, where we observed stable electron bunches with bunch width of approximately 80 μm. [ABSTRACT FROM AUTHOR]

Freshwater ecosystems contain a large diversity of microeukaryotes that play important roles in maintaining their structure. Microeukaryote communities vary in composition and abundance on the basis of temporal and environmental variables and may serve as useful bioindicators of environmental changes. In the present study, 18S rRNA metabarcoding was employed to investigate the seasonal diversity of microeukaryote communities during four seasons in the Han River, Korea. In total, 882 unique operational taxonomic units (OTUs) were detected, including various diatoms, metazoans (e.g., arthropods and rotifers), chlorophytes, and fungi. Although alpha diversity revealed insignificant differences based on seasons, beta diversity exhibited a prominent variation in the community composition as per seasons. The analysis revealed that the diversity of microeukaryotes was primarily driven by seasonal changes in the prevailing conditions of environmental water temperature and dissolved oxygen. Moreover, potential indicator OTUs belonging to diatoms and chlorophytes were associated with seasonal and environmental factors. This analysis was a preliminary study that established a continuous monitoring system using metabarcoding. This approach could be an effective tool to manage the Han River along with other freshwater ecosystems in Korea. [ABSTRACT FROM AUTHOR]

Purpose: Recently, high‐precision radiotherapy systems have been developed by integrating computerized tomography or magnetic resonance imaging to enhance the precision of radiotherapy. For integration with additional imaging systems in a limited space, miniaturization and weight reduction of the linear accelerator (linac) system have become important. The aim of this work is to develop a compact medical linac based on 9.3 GHz X‐band RF technology instead of the S‐band RF technology typically used in the radiotherapy field. Methods: The accelerating tube was designed by 3D finite‐difference time‐domain and particle‐in‐cell simulations because the frequency variation resulting from the structural parameters and processing errors is relatively sensitive to the operating performance of the X‐band linac. Through the 3D simulation of the electric field distribution and beam dynamics process, we designed an accelerating tube to efficiently accelerate the electron beam and used a magnetron as the RF source to miniaturize the entire linac. In addition, a side‐coupled structure was adopted to design a compact linac to reduce the RF power loss. To verify the performance of the linac, we developed a beam diagnostic system to analyze the electron beam characteristics and a quality assurance (QA) experimental environment including 3D lateral water phantoms to analyze the primary performance parameters (energy, dose rate, flatness, symmetry, and penumbra) The QA process was based on the standard protocols AAPM TG‐51, 106, 142 and IAEA TRS‐398. Results: The X‐band linac has high shunt impedance and electric field strength. Therefore, even though the length of the accelerating tube is 37 cm, the linac could accelerate an electron beam to more than 6 MeV and produce a beam current of more than 90 mA. The transmission ratio is measured to be approximately 30% ~ 40% when the electron gun operates in the constant emission region. The percent depth dose ratio at the measured depths of 10 and 20 cm was approximately 0.572, so we verified that the photon beam energy was matched to approximately 6 MV. The maximum dose rate was measured as 820 cGy/min when the source‐to‐skin distance was 80 cm. The symmetry was smaller than the QA standard and the flatness had a higher than standard value due to the flattening filter‐free beam characteristics. In the case of the penumbra, it was not sufficiently steep compared to commercial equipment, but it could be compensated by improving additional devices such as multileaf collimator and jaw. Conclusions: A 9.3 GHz X‐band medical linac was developed for high‐precision radiotherapy. Since a more precise design and machining process are required for X‐band RF technology, this linac was developed by performing a 3D simulation and ultraprecision machining. The X‐band linac has a short length and a compact volume, but it can generate a validated therapeutic beam. Therefore, it has more flexibility to be coupled with imaging systems such as CT or MRI and can reduce the bore size of the gantry. In addition, the weight reduction can improve the mechanical stiffness of the unit and reduce the mechanical load. [ABSTRACT FROM AUTHOR]

Simple Summary: Lingula anatina has been attracted researchers because its morphological characteristics show limited changes compared to the ancestor. Even though L. anatina is a common brachiopod in the western Pacific region, a few studies were performed to investigate genetic variations of this species. To understand the mitogenomic diversity of L. anatina in the region, the present study conducted comparative analyses of mitogenome sequences from Korea, Vietnam, and Japan. The sequencing results indicated that L. anatina mitogenomes are extraordinarily longer than the typical animal mitogenome. Besides, the gene orders of L. anatina mitogenomes are variable among localities. The calculation based on protein-coding genes revealed relatively low substitution rates among mitogenome sequences from Buan (Korea), Doson (Vietnam) and Yanagawa (Japan). The phylogenetic analyses indicated the divergence of L. anatina in the western Pacific region. This investigation provides new information on the molecular systematics of L. anatina and could be helpful in exploring the diversity and evolution of mitogenomes in brachipod. Lingula anatina is a brachiopod widely distributed in the western Pacific region. Even though L. anatina has been targeted for a number of biological studies, there is still limited information on intraspecific genetic variations of L. anatina. In this study, L. anatina specimens were collected from Korea and Vietnam, and complete mitochondrial genome (mitogenome) sequences were analyzed and compared with previous records. The total mitogenomes of L. anatina were 24,875 bp and 25,305 bp in size for Korean and Vietnamese specimens, respectively. Those mitogenomes are extraordinarily longer than the typical mitogenome size for an animal but shorter than the previous record from Yanagawa (Japan) for this species. The gene orders and the sizes of the protein-coding genes are also different from those for the Japanese specimen. Furthermore, the nonsynonymous (Ka) and synonymous (Ks) substitution rates in protein-coding genes (PCGs) were calculated to test the idea of evolutionary rate differences in mitochondrial genomes. The analyses showed relatively low Ka and Ks for the complete mitogenomes from Buan (Korea), Doson (Vietnam) and Yanagawa (Japan). The Ka/Ks ratio was less than 1 in comparisons of three localities, indicating the existence of purifying selection in this species. The phylogenetic analyses showed that L. anatina diverged among localities in the western Pacific region. [ABSTRACT FROM AUTHOR]

A compact X-band linear accelerator (LINAC) system equipped with a small and lightweight magnetron was constructed to develop a high-precision image-guided radiotherapy system. The developed LINAC system was installed in an O-ring gantry where cone-beam computed tomography (CBCT) was embedded. When the O-arm gantry is rotated, an x-ray beam is stably generated, which resulted from the stable transmission of radio frequency power into the X-band LINAC system. Quality assurance (QA) tests, including mechanical and dosimetry checks, were carried out to ensure safety and operation performance according to the American Association of Physicists in Medicine's TG-51, 142, an international standard protocol established by accredited institutions. In addition, delivery QA of the radiotherapy planning system was conducted to verify intensity-modulated radiotherapy techniques. Therefore, it was demonstrated that the developed X-band LINAC system mounted on the O-arm gantry proved to be valid and reliable for potential use in CBCT image-guided radiation therapy. [ABSTRACT FROM AUTHOR]

The internal architecture of a CVI reactor significantly influences the gas flow behavior, as well as the complex time-varying chemical reactions, but has been typically ignored in previous CVI models. Herein we developed, validated, and applied a fully three-dimensional (3D) physicochemical CVI model of an industry-scale reactor to simulate an isothermal CVI process for fabricating bulk carbon-carbon composites using methane as a precursor gas and a multi-layered preform consisting of a non-crimp fabric and felt. The flow inside the reactor was modeled using the Navier–Stokes equation, coupled with the convection-diffusion equation, to simulate the dispersive behaviors of the reactive gases inside the porous preform. The interactive molecular diffusion of methane (CH4), ethylene (C2H4), acetylene (C2H2), and benzene (C6H6) were modeled by considering the multi-step hydrocarbon reactions between the species. The hydrocarbon concentration changes, resulting from the carbon deposition on the preform surface, were computed to predict the evolution of the preform density and porosity. The current surface area of the preform was then determined based on the current porosity. The numerical results for the average preform density agreed well with the experimental data. In addition, the present model can provide detailed simulations of the temporal and spatial evolution of the preform density that cannot be experimentally observed. The effectiveness and utility of the developed model could benefit the design of CVI reactors and processes and minimize the need for test runs when processing conditions change. Image 1 • The actual industrial reactor is exclusively considered in a fully 3D setting. • Detailed physics and chemistry models are implemented for accurate CVI simulations. • Various hydrocarbon species through a transient kinetic model for chemical reactions. • CFD model with a convection-diffusion equation for fluid motions in the reactor. • Numerous insightful results about the spatial and temporal densification process. [ABSTRACT FROM AUTHOR]

TM330-like higher order mode was excited in a multibeam reflex klystron oscillator employing a hybrid photonic-band-gap (PBG) cavity using a three-dimensional particle-in-cell simulation. One side of a conventional metal cavity was replaced with a dielectric photonic crystal lattice to form a hybrid PBG resonator that uses lattice band-gap effects resulting in a more uniform field of a higher order mode as well as the exclusion of some conventional-cavity-type modes, thereby reducing mode competition. Simulated reflex klystron in the hybrid PBG cavity produced an output power much higher than could be delivered in a conventional metal cavity. [ABSTRACT FROM AUTHOR]

We demonstrate high speed scanning of a time-domain terahertz pulse by a rotary optical delay line (RODL) incorporated into a photoconductive antenna based terahertz system. The delay line of RODL consists of six rotating convex reflective blades with a rotating speed controlled for a wide range of scan repetition rates. It can perform path length scans of 2.1 cm at a scanning speed of 8.4 m/s while maintaining linearity. The comparison of the terahertz temporal waveform and the frequency spectrum measured by using the RODL and a linear stage optical delay line confirms the linearity of the RODL up to 140 ps at high scan repetition rates of 400 scan/s. A high signal-to-noise ratio, up to a few thousand, can be obtained by averaging multiple terahertz pulses at a high scan speed. [ABSTRACT FROM AUTHOR]

At least 246 cases of coronavirus disease (COVID-19) have been linked to nightclubs in Seoul, South Korea. During the April 30-May 5 holiday, young adults from across the country who visited nightclubs in Seoul contracted COVID-19 and spread it nationally. Nightclubs were temporarily closed to limit COVID-19 spread. [ABSTRACT FROM AUTHOR]

Welding fume exposure can increase the risk of chronic obstructive pulmonary disease (COPD). The aim of this study was to evaluate the optimal grouping schemes of welding fume exposure in shipyard welders for future accurate examination of the association between welding fume exposure and COPD. Industrial hygiene records, including welding fume measurements between 2002 and 2009 were collected from a shipyard. A total of 2,360 personal welding fume measurements was compiled with a geometric mean of 1.66 mg/m3 and a geometric standard deviation of 4.02. Welding jobs were categorized into 8 groups. There were 9 working areas. To obtain the optimal grouping scheme, various grouping schemes were created using job, area, and job*area combination. To compare various grouping schemes, contrast and precision were calculated for each grouping scheme. For all measurement data, group mean ranking method created by ranking geometric means of the job*area combination into 3 groups (group mean ranking method) showed the best contrast and precision values among various grouping schemes, followed by grouping based on the job. For a subset of the data excluding job*area combinations with less than 10 measurements, grouping based on the job showed greater contrast than group mean ranking method, while for other subsets, including only repeated measurement data or further excluding job*area combinations with less than 10 measurements from the repeated measurement subset, group mean ranking method showed greater contrast than grouping based on the job. Our results showed that group mean ranking or grouping based on the job could be a candidate for the optimal grouping schemes in this shipyard. Our efforts for optimal grouping scheme may aid future cohort study to elucidate the association between welding fume exposure and COPD. [ABSTRACT FROM AUTHOR]

Tabebuia avellanedae has been traditionally used as an herbal remedy to alleviate various diseases. However, the plant’s pharmacological activity in allergic and inflammatory diseases and its underlying mechanism are not fully understood. Therefore, we investigated the pharmacological activity of Tabetri (T. avellanedae ethanol extract (Ta-EE)) in the pathogenesis of AD. Its underlying mechanism was explored using an AD mouse model and splenocytes isolated from this model. Ta-EE ameliorated the AD symptoms without any toxicity and protected the skin of 2,4-dinitrochlorobenzene- (DNCB-) induced AD mice from damage and epidermal thickness. Ta-EE reduced the secreted levels of allergic and proinflammatory cytokines, including histamine, immunoglobulin E (IgE), interleukin- (IL-) 4, and interferon-gamma (IFN-γ) in the DNCB-induced AD mice. Ta-EE suppressed the mRNA expression of T helper 2-specific cytokines, IL-4 and IL-5, and the proinflammatory cytokine IFN-γ in the atopic dermatitis skin lesions of AD mice. Moreover, Ta-EE suppressed the mRNA expression of IL-4, IL-5, IFN-γ, and another proinflammatory cytokine, IL-12, in the Con A-stimulated splenocytes. It also suppressed IL-12 and IFN-γ in the LPS-stimulated splenocytes. Taken together, these results suggest that Ta-EE protects against the development of AD through the inhibition of mRNA expression of T helper 2-specific cytokines and other proinflammatory cytokines. [ABSTRACT FROM AUTHOR]

We report novel two-dimensional (2D) shaped carbon nanotube (CNT) field emitters using triangular-shaped CNT films and their field emission properties. Using the 2D shaped CNT field emitters, we achieved remarkable field emission performance with a high emission current of 22 mA (equivalent to an emission current density >10 5 A/cm 2 ) and long-term emission stability at 1 mA for 20 h. We also discuss the field emission behavior of the 2D shaped CNT field emitter in detail. [ABSTRACT FROM AUTHOR]

Abstract: Carbon fiber-reinforced SiC-matrix composites (Cf/SiC) were fabricated via a precursor infiltration and pyrolysis (PIP) process. A polycarbosilane (PCS) precursor was used, with a halogen element (iodine) for curing. The effects of high-temperature polycarbosilane infiltrate melting and iodine-based curing on the efficiency of the PIP process, as well as the physical characteristics of the fabricated Cf/SiC composites, were investigated. Highly dense Cf/SiC composites with strong fiber/matrix interfacial bonding were fabricated. By melting the infiltrate and using iodine-based preform curing, the ceramic yield of polycarbosilane increased drastically from 38wt% to 82wt%. This increase, which is due to pyrolysis, resulted in a low degree of shrinkage in the polycarbosilane-derived matrix. This shrinkage, in turn, increased the density of the Cf/SiC composites and improved the interfacial bonding between the matrix and fibers. As a result, the fabricated Cf/SiC composites exhibited a density of 1.75g/cm3. This was much higher than the 0.38g/cm3 density of bare carbon fiber preforms after 6 iterations of the PIP process. [Copyright &y& Elsevier]

Abstract: Sea tangle has long been used as Korean folk remedy to promote material health, and is one of the popular dietary supplement. This study was designed to evaluate the protective effect of fermented sea tangle (FST) against ethanol and carbon tetrachloride (CCl4)-induced hepatotoxicity in rats. Sprague–Dawley rats were orally treated with FST (25, 250, 2500mg/kg/day) with administration of ethanol (5mL/kg) for 13weeks and the single intraperitoneal (i.p.) dose of 50% CCl4 (5mL/kg/day, CCl4 in olive oil) at 12week, and repeated i.p. dose of 20% CCl4 (2mL/kg/day) for 1week. Hepatotoxicity was evaluated by measuring the serum levels of glutamic pyruvate transaminase (GPT), gamma glutamyl transpeptidase (γ-GT) and malondialdehyde (MDA) as well as the tissue levels of antioxidant enzyme such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). Ethanol and CCl4-induced the rat liver damage, and significantly increased (p <0.05) the GPT, γ-GT and MDA levels, and decreased the SOD, CAT and GPx levels. However, treatment with FST could decrease serum GPT, γ-GT, and MDA levels significantly in plasma, and increase the activities of SOD, CAT, and GPx in liver tissues compared with ethanol and CCl4-treated group. [Copyright &y& Elsevier]

We describe a fast measurement of a pulsed terahertz signal generated by a femtosecond laser and a photoconductive antenna using an oscillating optical delay line. The method to measure the amplitude of the retroreflector in the oscillating optical delay line is proposed and the displacement of the retroreflector is exactly calculated to acquire the optical delay time in the fast scan mode. With the different oscillation frequency and amplitude of the retroreflector, the pulsed terahertz signals are measured and analyzed. The comparison of the temporal waveform and frequency spectrum between the fast scan mode and the slow scan mode shows a good agreement with the decrease in the scanning time from 60 to 1 s at a signal to noise ratio of 430. [ABSTRACT FROM AUTHOR]

Background: The present study aims to compare the pulmonary function of residents of Seoul special city (Seoul) and Jeju special self-governing province including Jeju city and Seogwipo city (Jeju), characterized by vastly different annual average airborne particulate matter with an aerodynamic diameter less ≤10 μm (PM10) concentrations, with the annual average PM10 concentration in Seoul being significantly higher than that in Jeju. Methods: This cross-sectional study analyzed the pulmonary function test results and sociodemographic data of Korean adults ≥19 years of age derived from the 4th KNHANES, 2007–2009. A total of 830 individuals residing in Seoul or Jeju were included in this study. T-tests were used to analyze predicted values of forced expiratory volume in 1 sec (FEV1p), predicted values of forced vital capacity (FVCp) and FEV1/FVC ratio (FEV1/FVC), as dependent variables, to examine the differences in the subjects' pulmonary function according to the city of residence. Stratified analysis was then performed to adjust for variables potentially affecting pulmonary function. The analysis was performed on subjects as a group and also following stratification according to sex and other variables. Results: Seoul residents had a significantly lower FVCp than that of the Jeju residents (difference: 3.48%, p = 0.002). FEV1p, FVCp and FEV1/FVC of male Seoul residents were significantly lower than those of male Jeju residents (difference: 6.99, 5.11% and 0.03, respectively; p < 0.001, p = 0.001, p = 0.001). In male subjects, statistically significant results were obtained even after adjusting the influence of other variables through stratified analysis. Conclusion: The present analysis was based on cross-sectional data collected at one point in time. Therefore, unlike longitudinal studies, it does not establish a clear causal association between the variables. Nevertheless, this study found that pulmonary function among subjects residing in Seoul was significantly decreased compared to that of subjects residing in Jeju. [ABSTRACT FROM AUTHOR]