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Chemiresistive gas sensors based on semiconducting metal oxides typically rely on noble metal catalysts to enhance their sensitivity and selectivity. However, noble metal catalysts have several drawbacks for practical utilization, including their high cost, their propensity for spontaneous agglomeration, and poisoning effects with certain types of gases. As such, in the interest of commercializing the chemiresistive gas sensor technology, we propose an alternative design for a noble-metal-free sensing material through the case study of Co-doped ceria (Co-CeO2) catalysts embedded in a SnO2 matrix. In this investigation, we utilized electrospinning and subsequent calcination to prepare Co-CeO2 catalyst nanoparticles integrated with SnO2 nanofibers (NFs) with uniform particle distribution and particle size regulation down to the sub-2 nm regime. The resulting Co-CeO2@SnO2 NFs exhibited superior gas sensing characteristics toward isoprene (C5H8) gas, a significant biomarker for monitoring the onset of various diseases through breath diagnostics. In particular, we identified that the Co-CeO2 catalysts, owing to the transition metal doping, facilitated the spillover of chemisorbed oxygen species to the SnO2 sensing body. This resulting in the sensor having a 27.4-fold higher response toward 5 ppm of C5H8 (compared to pristine SnO2), exceptionally high selectivity, and a low detection limit of 100 ppb. The sensor also exhibited high stability for prolonged response-recovery cycles, attesting to the strong anchoring of Co-CeO2 catalysts in the SnO2 matrix. Based on our findings, the transition metal-doped metal oxide catalysts, such as Co-CeO2, demonstrate strong potential to completely replace noble metal catalysts, thereby advancing the development of the commercially viable chemiresistive gas sensors free from noble metals, capable of detecting target gases at sub-ppm levels.
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Although turtles play a key role in maintaining healthy and balanced environments, these are endangered due to global trade to meet the high demand for food, medicine, and pets in Asia. In addition, imported non-native turtles have been controlled as alien invasive species in various countries, including Korea. Therefore, a rapid and accurate classification of imported turtles is needed to conserve and detect those in native ecosystems. In this study, eight Single Shot MultiBox Detector (SSD) models using different backbone networks were used to classify 36 imported turtles in Korea. The images of these species were collected from Google and were identified using morphological features. Then, these were divided into 70% for training, 15% for validation, and 15% for test sets. In addition, data augmentation was applied to the training set to prevent overfitting. Among the eight models, the Resnet18 model showed the highest mean Average Precision (mAP) at 88.1% and the fastest inference time at 0.024 s. The average correct classification rate of 36 turtles in this model was 82.8%. The results of this study could help in management of the turtle trade, specifically in improving detection of alien invasive species in the wild.
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Aprendizaje Profundo , Tortugas , Animales , Ecosistema , Especies Introducidas , República de CoreaRESUMEN
Metal-organic frameworks (MOFs) have emerged as attractive chemical sensing materials due to their exceptionally high porosity and chemical diversity. Nevertheless, the utilization of MOFs in chemiresistive type sensors has been hindered by their inherent limitation in electrical conductivity. The recent emergence of two-dimensional conductive MOFs (2D c-MOFs) has addressed this limitation by offering enhanced electrical conductivity, while still retaining the advantageous properties of MOFs. In particular, c-MOFs have shown promising advantages for the fabrication of sensors capable of operating at room temperature. Thus, active research on gas sensors utilizing c-MOFs is currently underway, focusing on enhancing sensitivity and selectivity. To comprehend the potential of MOFs as chemiresistive sensors for future applications, it is crucial to understand not only the fundamental properties of conductive MOFs but also the state-of-the-art works that contribute to improving their performance. This comprehensive review delves into the distinctive characteristics of 2D c-MOFs as a new class of chemiresistors, providing in-depth insights into their unique sensing properties. Furthermore, we discuss the proposed sensing mechanisms associated with 2D c-MOFs and provide a concise summary of the strategies employed to enhance the sensing performance of 2D c-MOFs. These strategies encompass a range of approaches, including the design of metal nodes and linkers, morphology control, and the synergistic use of composite materials. In addition, the review thoroughly explores the prospects of 2D c-MOFs as chemiresistors and elucidates their remarkable potential for further advancements. The insights presented in this review shed light on future directions and offer valuable opportunities in the chemical sensing research field.
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This study introduces a promising technique to enhance the sensitivity of p-type semiconductors in gas-sensing applications. By utilizing a glycerate-templated synthesis approach, a unique hierarchical W-doped Co3O4 yolk-shell sphere (YSS)-based sensor was developed, exhibiting exceptional sensitivity toward acetone gas. The synthesized YSSs feature a yolk-shell structure with a diameter of approximately 500 nm and a large surface area of 117.46 m2/g, which allows for efficient gas interaction and high sensitivity toward acetone gas. Furthermore, the incorporation of tungsten (W), a non-noble metal, as a dopant significantly enhances the surface activity of Co3O4, leading to a remarkably high response of 16.5 toward 5 ppm acetone, which is substantially higher than that of the pure Co3O4 YSS (2.9). The W-doped Co3O4 YSS also exhibits excellent selectivity to other interfering gases and the ability to detect ultralow concentrations of acetone as low as 10 ppb. The proposed non-noble metal doping strategy presents a practical solution for enhancing the sensitivity and selectivity of p-type semiconductor-based gas sensors. This approach holds great potential for practical gas-sensing applications due to their affordability and abundance, making them a cost-effective and versatile alternative to noble metal-catalyzed sensors.
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Acetona , Tungsteno , Cobalto , Citoplasma , GasesRESUMEN
Due to the close relationship between pets and humans, pet owners are highly invested in proper diets for their pets. Even though pet food mislabeling is concerning, there are few studies on this topic. This study investigated pet food mislabeling in South Korea's market based on DNA barcoding. In total, 10 pet food products were purchased, and 200 sequences of the partial Cytochrome c oxidase subunit 1 (COI) gene were generated from clones of the samples. The obtained sequences were compared to available public databases to identify species present in the ingredients. The data analyses showed that the labeled species were consistent with species detected by COI sequences in 6 of the products. However, the expected species were not detected in 4 products, revealing possible mislabeling in these samples. Our findings indicated that DNA barcoding might represent a promising tool to detect pet food mislabeling.
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Although p-type semiconductors exhibit highly selective and stable chemiresistive gas sensing performances compared to conventional n-type semiconductors, their low sensitivity had long impeded their practical development. In this work, we developed highly porous Co3O4/CoMoO4 heterostructure nanosheets (NSs) with enhanced sensitivity and superior stability toward acetone gas through a facile solution-based approach with Mo-impregnated Co-based metal-organic frameworks as the starting material. The spontaneous formation of a large number of p-p heterojunctions at the Co3O4-CoMoO4 interface would facilitate the adsorption of oxygen and acetone molecules, as verified by density functional theory calculations. Consequently, experimental results showed that the Co3O4/CoMoO4 NSs have a greatly enhanced response of 8.5 toward 5 ppm acetone, which is 7.1 times higher than that of pure Co3O4 NS, without involving any noble metal catalysts. Moreover, the limit of detection of the Co3O4/CoMoO4 NSs was as low as 10 ppb. Altogether, we propose that our synthetic approach for the engineering of p-p heterojunctions is an effective strategy for the future development of highly practical and sensitive gas sensors based on p-type semiconductors.
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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.
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The process of exsolution for the synthesis of strongly anchored metal nanoparticles (NPs) on host oxide lattices has been proposed as a promising strategy for designing robust catalyst-support composite systems. However, because conventional exsolution processes occur in harsh reducing environments at high temperatures for long periods of time, the choice of support materials and dopant metals are limited to those with inherently high thermal and chemical stability. Herein, we report the exsolution of a series of noble metal catalysts (Pt, Rh, and Ir) from metal oxide nanofibers (WO3 NFs) supports in an entirely ambient environment induced by intense pulsed light (IPL)-derived momentary photothermal treatment (>1000 °C). Since the exsolution process spans an extremely short period of time (<20 ms), unwanted structural artifacts such as decreased surface area and phase transition of the support materials are effectively suppressed. At the same time, exsolved NPs (<5 nm) with uniform size distributions could successfully be formed. To prove the practical utility of exsolved catalytic NPs functionalized on WO3 NFs, the chemiresistive gas sensing characteristics of exsolved Pt-decorated WO3 NFs were analyzed, exhibiting high durability (>200 cyclic exposures), enhanced response (Rair/Rgas > 800 @ 1 ppm/350 °C), and selectivity toward H2S target gas. Altogether, we successfully demonstrated that ultrafast exsolution within a few milliseconds could be induced in ambient conditions using the IPL-derived momentary photothermal treatment and contributed to expanding the practical viability of the exsolution-based synthetic approaches for the production of highly stable catalyst systems.
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RATIONALE: Radiocarpal fracture-dislocations are extremely infrequent injuries caused by high-energy trauma and involve significant osseous and ligamentous injuries. If not treated properly, it can lead to serious complications such as ulnar translation of the carpus, multidirectional instability, loss of motion, and post-traumatic arthritis. Purely ligamentous injuries are rarer than fracture-dislocation injuries. Because previous studies have reported small patient cohorts, there has been no standardized treatment strategy for purely ligamentous radiocarpal dislocation. PATIENT CONCERNS: A 24-year-old man suffered a left wrist injury in a motorcycle accident. Plain radiographs revealed dorso-ulnar radiocarpal dislocation without radial fracture and Carpal-ulnar distance ratio (CUDR) was 0.16. MRI scans showed the disruption of the dorsal ligaments and capsules and avulsed from the proximal insertion of the volar radiocarpal ligaments. DIAGNOSIS: Dorsoulnar radiocarpal dislocation with purely ligamentous injury. INTERVENTION: We removed the interposing chondral fragment from the radiocarpal joint and repaired the radioscaphocapitate (RSC) and radiolunate (RL) ligaments with the Jugger Knot Soft Anchor Suture (Biomet, Inc, Warsaw, IN) and applied additional radiocarpal K-wires and an external fixator to maintain reduction and optimal ligament tension. OUTCOMES: The patient showed good clinical results although ulnar translation of the carpus recurred in radiological follow-up. LESSONS: Aggressive surgical management is needed earlier in the treatment of purely ligamentous radiocarpal dislocation, especially if the ulnar translation of the carpus was observed in the initial radiographs.
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Luxaciones Articulares/cirugía , Ligamentos Articulares/cirugía , Traumatismos de la Muñeca/cirugía , Accidentes de Tránsito , Hilos Ortopédicos , Fijadores Externos , Humanos , Luxaciones Articulares/diagnóstico por imagen , Ligamentos Articulares/diagnóstico por imagen , Ligamentos Articulares/lesiones , Imagen por Resonancia Magnética , Masculino , Motocicletas , Radiografía , Anclas para Sutura , Traumatismos de la Muñeca/diagnóstico por imagen , Adulto JovenRESUMEN
BACKGROUND: Recent evidence indicates brain ischemia is associated with accumulations of abnormal tau and related proteins. However, the effects of aerobic training on these proteins have not been evaluated. OBJECTIVE: We aimed to evaluate the effect of aerobic exercise on the phosphorylation and acetylation of tau and on the expressions of tau related proteins in a rat stroke model and to compare the effects of aerobic exercise with those observed in our previous study on task specific training (TST). METHODS: Twenty-four Sprague- Dawley rats with photothrombotic cortical infarction were used in the current study. The rehabilitation group (RG) received treadmill training 40âmin/day for 28 days, whereas the sedentary group (SG) did not receive any type of training. Functional tests such as the single pellet reaching task, rotarod, and radial arm maze tests were performed weekly for 4 weeks post-infarction. RESULTS: Levels of p-taus396 and p-AMPK were found to be lower in ipsilateral cortices in the RG than in the SG (pâ<â0.05). Levels of p-taus262, Ac-tau, p-GSK3ßS9, p-Akt, p-Sin1, and p-P70-S6K were significantly lower in ipsilateral than in contralateral cortices in the RG (pâ<â0.05). Aerobic training also improved motor, balance, and memory functions. CONCLUSION: Aerobic training inhibited the phosphorylation and acetylation of tau and modulated the expressions of tau related proteins after stroke by modifying the p70-S6K pathway and p-AMPK. By comparison with our previous study on the effects of TST, we have evidence to suggest that TST and aerobic exercise differ, although both types of rehabilitation inhibit tau phosphorylation and acetylation.
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Isquemia Encefálica/fisiopatología , Infarto/fisiopatología , Accidente Cerebrovascular/fisiopatología , Proteínas tau/metabolismo , Animales , Infarto/inducido químicamente , Masculino , Fosforilación , Condicionamiento Físico Animal/fisiología , Ratas Sprague-Dawley , Rehabilitación de Accidente Cerebrovascular/métodosRESUMEN
PURPOSE: To compare the implant position and patient-reported outcomes (PROs) regarding joint awareness using the Forgotten Joint Score (FJS) following between fixed-bearing (FB) and mobile-bearing (MB) unicompartmental knee arthroplasty (UKA) with a minimum of five years' follow-up. METHODS: One hundred fifteen consecutive UKAs (58 FB UKAs and 57 MB UKAs) performed were retrospectively evaluated. We compared the radiographic parameters including component positions and relationships as well as lower extremity alignment. Post-operative clinical outcomes were assessed using Knee Society Score (KSS), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, Tegner activity score, and FJS. RESULTS: The MB UKA group showed more convergent componentry relationship between femoral and tibial components (p < 0.001). The joint line of the MB UKA group was restored significantly better (p < 0.05). In addition, the positioning of femoral and tibial components of the MB UKA group showed less deviation from the weight-bearing line (WBL) (p < 0.05). Although there were no differences in KSS, WOMAC, and Tegner activity scores between the groups, the MB UKA group showed significantly better FJS than did the FB UKA group at five years post-operatively (p < 0.05). CONCLUSION: The MB UKA group had a more convergent componentry relationship, less deviation from WBL, better joint-line restoration, and reduced joint awareness than did the FB UKA group at five years follow-up.
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Artroplastia de Reemplazo de Rodilla , Prótesis de la Rodilla , Osteoartritis de la Rodilla , Artroplastia de Reemplazo de Rodilla/efectos adversos , Estudios de Seguimiento , Humanos , Articulación de la Rodilla/diagnóstico por imagen , Articulación de la Rodilla/cirugía , Prótesis de la Rodilla/efectos adversos , Osteoartritis de la Rodilla/cirugía , Estudios Retrospectivos , Resultado del TratamientoRESUMEN
Keratoplasty, which is cornea transplant surgery, is one of the treatment methods for patients with turbidity or keratitis. Recently, keratoplasty using a surgical robot was studied to increase precision. In this study, the effect of surgical factors on the deformation and curvature of the cornea were analyzed in order to improve the accuracy of keratoplasty and derive the optimal surgical factors using finite element method (FEM). Suturing tension and depth were selected as surgical factors. An FEM model, a constitutive equation, and boundary conditions were determined using experiments and reference data. Suturing tension significantly impacted deformation and curvature change, and suturing depth affected the position of the thread-cornea contact point. Both factors have a significant impact on a focal point in the retina and the patient's visual acuity after keratoplasty.