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1.
J Environ Manage ; 365: 121493, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38897081

RESUMEN

Frequently occurring extreme weather events can pose a challenge to people and production systems. Coping with extreme high temperatures requires promoting the synergy between pollution reduction and carbon reduction. Accordingly, this study examines the causal relationship between extreme high temperatures and corporate pollution emissions by using the panel data of a Chinese sample from 2000 to 2014. This study uses fixed-effects models for the analysis. Baseline results show that a unit increase in the standardized temperature will result in a 4.6% reduction in corporate pollutant emissions. The heterogeneous analysis shows that extreme high temperatures will have an obvious effect on enterprises with low financing constraints and high policy and public constraints as well as on enterprises in cities with a high level of economic development, in innovative cities, and in the eastern region. We also explore the mechanism through which extreme high temperatures reduce pollutant emissions from the two dimensions of external environmental pressure and internal environmental governance. Extreme high temperatures will prompt enterprises to improve their energy efficiency, engage in innovative production processes, adopt source-and-end governance measures, and curb their pollutant emissions while strengthening government environmental supervision. This study provides new ideas for enterprise pollution reduction and serves as an inspiration to the government in formulating environmental policies.


Asunto(s)
Ciudades , China , Contaminación Ambiental , Contaminación del Aire/análisis , Política Ambiental
2.
Opt Express ; 31(5): 7554-7563, 2023 Feb 27.
Artículo en Inglés | MEDLINE | ID: mdl-36859884

RESUMEN

Phase evolution of soliton and that of first-order sidebands in a fiber laser are investigated by using nonlinear Fourier transform (NFT). Development from dip-type sidebands to peak-type (Kelly) sidebands is presented. The phase relationship between the soliton and the sidebands calculated by the NFT are in good agreement with the average soliton theory. Our results suggest that NFT can be an effective tool for the analysis of laser pulses.

3.
Opt Express ; 31(13): 21452-21463, 2023 Jun 19.
Artículo en Inglés | MEDLINE | ID: mdl-37381244

RESUMEN

We investigate the polarization dynamics of vector solitons in a fiber laser mode-locked by a saturable absorber (SA). Three types of vector solitons were obtained in the laser, including group velocity locked vector solitons (GVLVS), polarization locked vector solitons (PLVS), and polarization rotation locked vector solitons (PRLVS). Their polarization evolution during intracavity propagation is discussed. Pure vector solitons are obtained from the continuous wave (CW) background by soliton distillation, and the characteristics of the vector solitons without and with distillation are analyzed, respectively. Numerical simulations suggest that the features of vector solitons in a fiber laser could be assemble to those generated in fibers.

4.
J Environ Manage ; 332: 117385, 2023 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-36738719

RESUMEN

Physical health has been associated with ambient temperature and heatwave. With the frequent occurrence of heatwave, the adaptive effects and mechanisms on mental health remain uncertain. On the basis of the China Health and Nutrition Survey, we estimated the relationship between heatwaves and self-assessed mental health scores in the Chinese population aged 50 and above. This study has identified that with each additional heatwave event, mental health scores decreased by an average of 0.027 points, which is equivalent to 0.3% of the average level. Heat is more likely to affect groups with low education, no medical insurance, and living in rural areas. In mechanistic exploration, we found that stress emotion is a fully mediating effect. Heat led to reduced health activities and more frequent drinking, which may lead to lower psychological well-being. Moreover, good dietary preference is a regulator that can help mitigate the adverse effects of heat on mental health. This study corroborates the impact of heat on spiritual welfare, and demonstrates the mechanisms and channels of impact, which can help reduce global economic losses due to mental health problems.


Asunto(s)
Calor , Salud Mental , China
5.
BMC Genomics ; 23(1): 376, 2022 May 18.
Artículo en Inglés | MEDLINE | ID: mdl-35585506

RESUMEN

BACKGROUND: Within the class Enoplea, the earliest-branching lineages in the phylum Nematoda, the relatively highly conserved ancestral mitochondrial architecture of Trichinellida is in stark contrast to the rapidly evolving architecture of Dorylaimida and Mermithida. To better understand the evolution of mitogenomic architecture in this lineage, we sequenced the mitogenome of a fish parasite Pseudocapillaria tomentosa (Trichinellida: Capillariidae) and compared it to all available enoplean mitogenomes. RESULTS: P. tomentosa exhibited highly reduced noncoding regions (the largest was 98 bp), and a unique base composition among the Enoplea. We attributed the latter to the inverted GC skew (0.08) in comparison to the ancestral skew in Trichinellidae (-0.43 to -0.37). Capillariidae, Trichuridae and Longidoridae (Dorylaimida) generally exhibited low negative or low positive skews (-0.1 to 0.1), whereas Mermithidae exhibited fully inverted low skews (0 to 0.05). This is indicative of inversions in the strand replication order or otherwise disrupted replication mechanism in the lineages with reduced/inverted skews. Among the Trichinellida, Trichinellidae and Trichuridae have almost perfectly conserved architecture, whereas Capillariidae exhibit multiple rearrangements of tRNA genes. In contrast, Mermithidae (Mermithida) and Longidoridae (Dorylaimida) exhibit almost no similarity to the ancestral architecture. CONCLUSIONS: Longidoridae exhibited more rearranged mitogenomic architecture than the hypervariable Mermithidae. Similar to the Chromadorea, the evolution of mitochondrial architecture in enoplean nematodes exhibits a strong discontinuity: lineages possessing a mostly conserved architecture over tens of millions of years are interspersed with lineages exhibiting architectural hypervariability. As Longidoridae also have some of the smallest metazoan mitochondrial genomes, they contradict the prediction that compact mitogenomes should be structurally stable. Lineages exhibiting inverted skews appear to represent the intermediate phase between the Trichinellidae (ancestral) and fully derived skews in Chromadorean mitogenomes (GC skews = 0.18 to 0.64). Multiple lines of evidence (CAT-GTR analysis in our study, a majority of previous mitogenomic results, and skew disruption scenarios) support the Dorylaimia split into two sister-clades: Dorylaimida + Mermithida and Trichinellida. However, skew inversions produce strong base composition biases, which can hamper phylogenetic and other evolutionary studies, so enoplean mitogenomes have to be used with utmost care in evolutionary studies.


Asunto(s)
Genoma Mitocondrial , Nematodos , Animales , Composición de Base , Chromadorea/genética , Evolución Molecular , Nematodos/genética , Filogenia
6.
J Environ Manage ; 311: 114842, 2022 Mar 07.
Artículo en Inglés | MEDLINE | ID: mdl-35272162

RESUMEN

By using 64,270 daily observations from a large hospital in Guangzhou between 2017 and 2019, we analyzed the impact of extreme temperature on the health of newborns via OLS regression with time fixed effect. Given that the short-term temperature change can be regarded as exogenous and random, solving the potential endogenous problem is critical. We find that extreme temperature negatively affects the health of newborns. The Apgar score, an index for evaluating neonatal health, decreases by 0.008 (0.029%) when the duration of extreme temperature events increases by a day. A series of robustness checks verify the reliability of this negative effect. Extreme temperature also has a particularly serious effect on the health of newborns whose mothers have poor education. By gradually extending the observation period, we find that the effect of extreme temperature on neonatal health is mainly concentrated 1-6 weeks before delivery, whereas the effect of extreme temperature on hospitalization cost is mainly concentrated 4-8 weeks before delivery. This paper provides a valuable reference for evaluating the health and social costs of extreme weather, and our findings are conducive to the construction of climate-resilient health systems, especially in Guangzhou.

7.
J Clean Prod ; 279: 123622, 2021 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-32834571

RESUMEN

With the outbreak of COVID-19 (Corona Virus Disease, 2019), China adopted traffic restrictions to reduce the spread of COVID-19. Using daily data before and after the outbreak of COVID-19, an exogenous shock, this paper analyzes the effects of private vehicle restriction policies on air pollution. We find that the private vehicle restriction policies reduce the degree of air pollution to a certain extent. However, their effect varies with other policies implemented in the same period and the economic development of the city itself. Through the analysis of different categories of restrictions, we find that restriction policy for local fuel vehicles and the restriction policy based on the last digit of license plate numbers have the best effect in reducing air pollution. Under the background of COVID-19 epidemic and the implementation of private vehicle restriction policies and other traffic control policies during this period, we have also obtained other enlightenment on air pollution control.

8.
Angew Chem Int Ed Engl ; 59(27): 10836-10841, 2020 Jun 26.
Artículo en Inglés | MEDLINE | ID: mdl-32237022

RESUMEN

Most ternary sulfides belonging to the MGaS2 structure-type have been known for many years and are well-characterized. Surprisingly, there have been no reports of the NaGaS2 composition, which contains Na, a monovalent cation slightly larger in size than Li, found in LiGaS2 , a compound known for its non-linear optical properties. Now it is demonstrated for the first time that the unique reversible water absorption in NaGaS2 has resulted in its absence from previous reports owing to difficulties encountered when characterizing this compound by SC XRD. The layered structure of this compound coupled with uniquely easy migration of water molecules between the layers allows for ion exchange with 3d and 5f metal cations. Some cations, for example, Ni2+ , facilitate exfoliation of the layers, providing a facile synthetic route to a new class of 2D chalcogenide materials and furthermore demonstrating that NaGaS2 can readily uptake uranyl species from aqueous solutions.

9.
J Vasc Res ; 53(3-4): 172-185, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27732975

RESUMEN

BACKGROUND/AIM: H2S is a novel vasoactivator. To verify the hypothesis that H2S may act as an endothelium-derived hyperpolarizing factor (EDHF) in the rat cerebrovasculature, the role of H2S in endothelium-derived relaxing factor (EDRF)-mediated responses was investigated. METHODS: Cystathionine-γ-lyase (CSE) was knocked down with an siRNA technique. Artery diameter, hyperpolarization and Ca2+-activated K+ (KCa) current were measured. RESULTS: CSE knockdown was indicated by a decrease in protein and mRNA expression in the rat middle cerebral artery (MCA) and cerebral basilar artery (CBA). Acetylcholine (ACh) induced significant hyperpolarization and vasodilation in endothelium-intact MCA and CBA. Removal of the endothelium abolished these responses. The nitric oxide (NO) synthase inhibitor L-NAME, but not the PGI2 production inhibitor indomethacin, significantly inhibited ACh-induced hyperpolarization and vasodilation in the CBA. In the presence of L-NAME and indomethacin, ACh-induced hyperpolarization and vasodilation in the MCA and CBA were attenuated. The non-NO/PGI2-mediated responses were abolished by the KCa channel blockers charybdotoxin and apamin. In the cerebral arteries from the CSE knockdown rat, non-NO/PGI2-mediated responses were significantly attenuated, and the remaining responses were abolished by charybdotoxin and apamin or the CSE inhibitor propargylglycine. CSE knockdown did not affect L-NAME-sensitive responses in the CBA. Sodium hydrosulfide (NaHS) augmented the KCa current in CBA vascular smooth muscle cells. CONCLUSION: EDHF-mediated responses in rat cerebral arteries were due to H2S activating the KCa channel.


Asunto(s)
Arteria Basilar/metabolismo , Factores Biológicos/metabolismo , Sulfuro de Hidrógeno/metabolismo , Arteria Cerebral Media/metabolismo , Vasodilatación , Animales , Arteria Basilar/efectos de los fármacos , Arteria Basilar/enzimología , Inhibidores de la Ciclooxigenasa/farmacología , Cistationina gamma-Liasa/genética , Cistationina gamma-Liasa/metabolismo , Relación Dosis-Respuesta a Droga , Epoprostenol/metabolismo , Masculino , Potenciales de la Membrana , Arteria Cerebral Media/efectos de los fármacos , Arteria Cerebral Media/enzimología , Óxido Nítrico/metabolismo , Óxido Nítrico Sintasa/antagonistas & inhibidores , Óxido Nítrico Sintasa/metabolismo , Bloqueadores de los Canales de Potasio/farmacología , Canales de Potasio Calcio-Activados/metabolismo , Interferencia de ARN , ARN Interferente Pequeño/administración & dosificación , Ratas Sprague-Dawley , Transducción de Señal , Vasodilatación/efectos de los fármacos , Vasodilatadores/farmacología
10.
J Am Chem Soc ; 136(23): 8374-86, 2014 Jun 11.
Artículo en Inglés | MEDLINE | ID: mdl-24826843

RESUMEN

Periodic density functional theory (DFT) calculations and microkinetic modeling are used to investigate the electrochemical oxidation of H2 fuel on the (001) surface of Sr2Fe1.5Mo0.5O6 (SFMO) perovskite under anodic solid oxide fuel cell conditions. Three surface models with different Fe/Mo ratios in the topmost layer-identified by ab initio thermodynamic analysis-are used to investigate the H2 oxidation mechanism. A microkinetic analysis that considers the effects of anode bias potential suggests that a higher Mo concentration in the surface increases the activity of the surface toward H2 oxidation. At operating voltage and anodic SOFC conditions, the model predicts that water desorption is rate-controlling and that stabilizing the oxygen vacancy structure increases the overall rate for H2 oxidation. Although we find that Mo plays a crucial role in improving catalytic activity of SFMO, under fuel cell operating conditions, the Mo content in the surface layer tends to be very low. On the basis of these results and in agreement with previous experimental observations, a strategy for improving the overall electrochemical performance of SFMO is increasing the Mo content or adding small amounts of an active transition metal, such as Ni, to the surface to lower the oxygen vacancy formation energy of the SFMO surface.

11.
Inorg Chem ; 53(21): 11484-91, 2014 Nov 03.
Artículo en Inglés | MEDLINE | ID: mdl-25338760

RESUMEN

Hierarchical cubelike submicrometer PbS particles consisting of truncated octahedrons, cuboctahedrons, and cubes were prepared in ethylene glycol solution under favorable high mole ratio of thiourea (Tu) to Pb(AC)2 (R(S/Pb)) via a pumping process. A qualitative analysis based on the classical nucleation theory coupled with the crystal growth theory is employed to interpret the observed experimental phenomena. By varying the concentration of reactants, R(S/Pb), and reaction temperature, it is possible to tune the local supersaturation degree (LSD), which is determined by the number of nuclei and overall growth unit (or concentration), surrounding each growing particle that dictates the branching and faceting of PbS particle. Relatively high LSD that is required for branching growth could be achieved at lower concentration of Tu and reaction temperature. Increasing the concentration of Tu and reaction temperature resulted in less LSD and yielded cubic PbS particles.

12.
ScientificWorldJournal ; 2014: 749096, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-25126604

RESUMEN

Biometric recognition (also known as biometrics) refers to the automated recognition of individuals based on their biological or behavioral traits. Examples of biometric traits include fingerprint, palmprint, iris, and face. The brain is the most important and complex organ in the human body. Can it be used as a biometric trait? In this study, we analyze the uniqueness of the brain and try to use the brain for identity authentication. The proposed brain-based verification system operates in two stages: gray matter extraction and gray matter matching. A modified brain segmentation algorithm is implemented for extracting gray matter from an input brain image. Then, an alignment-based matching algorithm is developed for brain matching. Experimental results on two data sets show that the proposed brain recognition system meets the high accuracy requirement of identity authentication. Though currently the acquisition of the brain is still time consuming and expensive, brain images are highly unique and have the potential possibility for authentication in view of pattern recognition.


Asunto(s)
Algoritmos , Identificación Biométrica/métodos , Identificación Biométrica/tendencias , Sustancia Gris/anatomía & histología , Procesamiento de Imagen Asistido por Computador/métodos , Neuroimagen/métodos , Neuroimagen/tendencias , Humanos , Imagen por Resonancia Magnética
13.
Molecules ; 19(2): 1592-602, 2014 Jan 27.
Artículo en Inglés | MEDLINE | ID: mdl-24473215

RESUMEN

Resveratrol-4-O-D-(2'-galloyl)-glucopyranoside (RESG) is one of the active compounds isolated from Polygonum cuspidatum. The purpose of our present study was to investigate the anti-hepatocellular carcinoma effect of RESG in vitro and in vivo, and the possible mechanisms in vitro. In vitro, our results showed that RESG could significantly inhibit the human hepatocellular carcinoma viability in the MTT assay, in a dose- and time-dependent manner. Furthermore, our results demonstrated that RESG could induce SMMC-7721 cell apoptosis and activate caspases 3 and caspases 9 by using Annexin V-FITC staining and western blot, respectively. In vivo, RESG also showed efficacy in SMMC-7721 xenograft model in nude mice, and further molecule mechanisms were investigated in vitro. The results showed that RESG up-regulated the p-JNK expressions, whereas it down-regulated the p-ERK expressions. Above results demonstrated that RESG is a potential therapeutic agent for hepatocellular carcinoma via JNK and ERK pathway to induce apoptosis. Our finding provided a basis for further development of RESG as an anticancer agent.


Asunto(s)
Carcinoma Hepatocelular/tratamiento farmacológico , Glucurónidos/farmacología , Neoplasias Hepáticas/tratamiento farmacológico , Extractos Vegetales/farmacología , Estilbenos/farmacología , Animales , Apoptosis/efectos de los fármacos , Carcinoma Hepatocelular/patología , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Fallopia japonica/química , Glucurónidos/química , Humanos , Neoplasias Hepáticas/patología , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Ratones , Extractos Vegetales/química , Estilbenos/química , Ensayos Antitumor por Modelo de Xenoinjerto
14.
Genes Dis ; 11(4): 101019, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38560496

RESUMEN

Tendon injuries often lead to joint dysfunction due to the limited self-regeneration capacity of tendons. Repairing tendons is a major challenge for surgeons and imposes a significant financial burden on society. Therefore, there is an urgent need to develop effective strategies for repairing injured tendons. Tendon tissue engineering using hydrogels has emerged as a promising approach that has attracted considerable interest. Hydrogels possess excellent biocompatibility and biodegradability, enabling them to create an extracellular matrix-like growth environment for cells. They can also serve as a carrier for cells or other substances to accelerate tendon repair. In the past decade, numerous studies have made significant progress in the preparation of hydrogel scaffolds for tendon healing. This review aims to provide an overview of recent research on the materials of hydrogel-based scaffolds used for tendon tissue engineering and discusses the delivery systems based on them.

15.
Am J Sports Med ; 52(2): 461-473, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38426316

RESUMEN

BACKGROUND: Treatment options for calcific tendinitis (CT) of the shoulder remain controversial. A consensus for an operative indication for this condition is lacking. PURPOSE: To compare nonoperative versus operative treatment for shoulder CT and analyze factors affecting the prognosis after treatment. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 180 patients diagnosed with symptomatic CT between January 2017 and September 2021 were evaluated in this retrospective cohort study. There were 103 patients treated nonoperatively at our institution, which included the use of nonsteroidal anti-inflammatory drugs, acupuncture, steroid injections, extracorporeal shock wave therapy, and ultrasound-guided needle aspiration/percutaneous irrigation. However, 77 patients were treated with arthroscopic surgery after 6 months of failed nonoperative treatment. The visual analog scale (VAS) for pain, the Constant-Murley score, and imaging were used to assess and evaluate outcomes. Descriptive data, functional outcomes, and imaging findings were compared between the operative and nonoperative groups before and after propensity score matching. Additionally, prognostic factors including calcium deposit size, tendon infiltration by calcium deposits, involvement of single or multiple tendons, and occurrence of rotator cuff tears were analyzed by comparing the groups to determine their effect on treatment options and recovery. RESULTS: Magnetic resonance imaging showed that the supraspinatus tendon (66.7%) was most commonly involved, followed by the infraspinatus (42.8%) and subscapularis (21.1%) tendons. Tendon infiltration by calcium deposits was observed in 84.4% of the patients, and rotator cuff tears occurred in 30.0% of the patients. After propensity score matching, there was no significant difference in changes in the Constant-Murley score (48.1 ± 25.4 vs 49.0 ± 22.8, respectively; P = .950) and VAS score (4.9 ± 2.3 vs 4.5 ± 1.9, respectively; P = .860) between the operative and nonoperative groups at the final follow-up. However, for patients with shoulder CT and without rotator cuff tears, there was a significant difference in changes in the Constant-Murley score (52.93 ± 25.18 vs 42.13 ± 22.35, respectively; P = .012) and VAS score (5.21 ± 2.06 vs 3.81 ± 1.98, respectively; P < .001) between the operative and nonoperative groups, but the recovery time in the operative group was longer than that in the nonoperative group (86.92 ± 138.56 vs 30.42 ± 54.97 days, respectively; P = .016). The results also showed that calcium deposit size, involvement of multiple tendons, and tendon infiltration by calcium deposits did not affect the recovery time after treatment. The survival analysis showed that rotator cuff tears affected the complete recovery of shoulder function. CONCLUSION: This study demonstrated no significant difference between nonoperative and operative treatment for patients with shoulder CT, on the whole. However, for patients with shoulder CT and without rotator cuff tears, the effect of operative treatment was better than that of nonoperative treatment; yet, operative treatment was shown to prolong the recovery time. Calcium deposit size, tendon infiltration by calcium deposits, and involvement of multiple tendons did not correlate with recovery time or the recovery of function. A rotator cuff tear was the only factor affecting the complete recovery of shoulder function.


Asunto(s)
Lesiones del Manguito de los Rotadores , Tendinopatía , Humanos , Hombro/cirugía , Lesiones del Manguito de los Rotadores/diagnóstico por imagen , Lesiones del Manguito de los Rotadores/cirugía , Estudios de Cohortes , Artroscopía/métodos , Estudios Retrospectivos , Calcio , Resultado del Tratamiento , Imagen por Resonancia Magnética , Tendinopatía/diagnóstico por imagen , Tendinopatía/terapia
16.
Int J Parasitol Parasites Wildl ; 23: 100894, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38187442

RESUMEN

This study aimed to examine the prevalence of Ichthyophthirius multifiliis in fish inhabiting natural water bodies in the Lhasa and Nagqu regions of Tibet in September 2020 and August 2021. The results showed that Schizopygopsis selincuoensis had the highest prevalence of I. multifiliis at 33.73% (56/166), followed by Triplophysa tibetana at 30.00% (6/20), Triplophysa brevicauda at 27.91% (12/43) and Schizopygopsis thermalis at 23.66% (31/131). No infection with I. multifiliis was observed in exotic fish species. In addition, the prevalence of I. multifiliis in Boqu Zangbo (river), Selincuo Lake and Cuona Lake in the Nagqu region was found to be significantly higher than that in Lalu Wetland and Chabalang Wetland in the Lhasa region (P < 0.05). The study revealed a significantly lower prevalence in Lhasa River than in Cuona Lake (P < 0.05). Notably, our findings revealed instances of I. multifiliis infections even in saline water bodies, thereby emphasizing the potential threat that this parasite poses to the preservation of indigenous fish resources in Tibet. Consequently, immediate and effective countermeasures are imperative. This study represents the first systematic investigation of I. multifiliis infection in natural water bodies in Tibet.

17.
IEEE Trans Image Process ; 32: 2003-2016, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-35839180

RESUMEN

Typical methods for pedestrian detection focus on either tackling mutual occlusions between crowded pedestrians, or dealing with the various scales of pedestrians. Detecting pedestrians with substantial appearance diversities such as different pedestrian silhouettes, different viewpoints or different dressing, remains a crucial challenge. Instead of learning each of these diverse pedestrian appearance features individually as most existing methods do, we propose to perform contrastive learning to guide the feature learning in such a way that the semantic distance between pedestrians with different appearances in the learned feature space is minimized to eliminate the appearance diversities, whilst the distance between pedestrians and background is maximized. To facilitate the efficiency and effectiveness of contrastive learning, we construct an exemplar dictionary with representative pedestrian appearances as prior knowledge to construct effective contrastive training pairs and thus guide contrastive learning. Besides, the constructed exemplar dictionary is further leveraged to evaluate the quality of pedestrian proposals during inference by measuring the semantic distance between the proposal and the exemplar dictionary. Extensive experiments on both daytime and nighttime pedestrian detection validate the effectiveness of the proposed method.

18.
ACS Appl Mater Interfaces ; 15(25): 30139-30151, 2023 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-37314993

RESUMEN

The electrochemical oxidation of H2 and CO fuels have been investigated on the Ruddlesden-Popper layered perovskite SrLaFeO4-δ (SLF) under anodic solid oxide fuel cell conditions using periodic density functional theory and microkinetic modeling techniques. Two distinct FeO2-plane-terminated surface models differing in terms of the underlying rock salt layer (SrO or LaO) are used to identify the active site and limiting factors for the electro-oxidation of H2, CO, and syngas fuels. Microkinetic modeling predicted an order of magnitude higher turnover frequency for the electro-oxidation of H2 compared to CO for SLF at short-circuit conditions. The surface model with an underlying SrO layer was found to be more active with respect to H2 oxidation than the LaO-based surface model. At an operating voltage of less than 0.7 V, surface H2O/CO2 formation was found to be the key rate-limiting step, and the surface H2O/CO2 desorption was the key charge transfer step. In contrast, the bulk oxygen migration process was found to affect the overall rate at high cell voltage conditions above 0.9 V. In the presence of syngas fuel, the overall electrochemical activity is derived mainly from H2 electro-oxidation and CO2 is chemically shifted to CO via the reverse water-gas shift reaction. Substitutional doping of a surface Fe atom with Co, Ni, and Mn revealed that the H2 electro-oxidation activity of FeO2-plane terminated anodes with an underlying LaO rock salt layer can be improved with dopant introduction, with Co yielding a three orders of magnitude higher activity relative to the undoped LaO surface model. Constrained ab initio thermodynamic analysis furthermore suggested that the SLF anodes are resistant toward sulfur poisoning both in the presence and absence of dopants. Our findings reflect the role of various elements in controlling the fuel oxidation activity of SLF anodes that could aid the development of new Ruddlesden-Popper phase materials for fuel cell applications.

19.
J Orthop Surg Res ; 18(1): 719, 2023 Sep 23.
Artículo en Inglés | MEDLINE | ID: mdl-37741994

RESUMEN

BACKGROUND: This study analyzed the advantages and disadvantages of different procedures for stage IIA progressive collapsing foot deformity (PCFD) through three-dimensional finite element models. METHODS: A previous validated stage IIA PCFD FEA model was established consisting of 16 bones, 56 ligaments, 5 muscles and soft tissues. The ligament properties of the spring, deltoid, short plantar and long plantar ligaments, and plantar fascia were attenuated according to a previous publication. Medial column fusion (MCF), medializing calcaneal osteotomy (MCO), lateral column lengthening (LCL), and subtalar joint arthroereisis (SJA) operations were simulated in this model. The indexes of plantar stress distribution, maximum von Mises of the medial and lateral columns, strain of the medial ligaments and plantar fascia that supported the medial longitudinal arch, arch height, talo-first metatarsal angle, calcaneus pitch angle, and talonavicular coverage angle were all compared before and after simulated single-foot weight loading. RESULTS: The maximum plantar stress of PCFD decreased with MCO and SJA but increased with MCF and LCL. MCF and LCL failed to significantly reduce the stress on the medial column fragments, thereby increasing their stress. Both MCO and SJA relieved medial plantar stress. MCF had no significant effect on stress relief of the medial ligament. MCO, LCL, and SJA were all shown to reduce the pressure on the medial plantar ligament, with LCL having the most obvious effect. All four procedures corrected the arch deformity; however, MCF was not as effective as the other methods. SJA is the best method for restoring arch height and correcting arch deformities. For stage IIA PCFD, isolated MCF failed to reduce pressure on the medial column; however, isolated MCO significantly reduced the pressure on the medial plantar and ligamentous soft tissues while restoring the foot's arch and correcting the hindfoot valgus. CONCLUSION: SJA with type II sinus tarsi implant effectively transferred pressure from the medial plantar tract to the lateral side and restored the arch. Isolated LCL was not found suitable for stage IIA PCFD.


Asunto(s)
Deformidades del Pie , Humanos , Análisis de Elementos Finitos , Pie/cirugía , Ligamentos Articulares
20.
ACS Appl Mater Interfaces ; 15(42): 49785-49793, 2023 Oct 25.
Artículo en Inglés | MEDLINE | ID: mdl-37816140

RESUMEN

Highly active triple (proton, oxygen-ion, and electron) conducting materials BaxCo0.4Fe0.4Zr0.1Y0.1O3-δ (BxCFZY, x = 0.9-1.1) were prepared and characterized as potential cathodes for protonic ceramic fuel cells (PCFCs) in this work. The crystal structure, oxygen vacancy concentration, electrical conductivity, oxygen ion transfer properties, and electrochemical performance of BxCFZY oxides were systematically evaluated. The electrical conductivity of BxCFZY decreases but oxygen vacancies increase with increasing Ba content, indicating that the charge compensation was mainly achieved by the production of oxygen vacancy rather than the increase in the valence of transition metal cations. The power density of 1170 mW cm-2 and the polarization resistance of 0.05 Ω cm2 were achieved at 700 °C for the anode-supported single cells with B1.1CFZY cathode, suggesting that the excess A site on the BxCFZY had a positive effect on the catalytic activity for the oxygen reduction reaction. Furthermore, the distribution of relaxation time (DRT) analysis method was adopted to determine the electrochemical processes of the cells with BxCFZY cathodes. The calculated results confirmed that the cell with B1.1CFZY cathode exhibited the optimum performance due to the best oxygen ion transfer properties in BxCFZY cathodes.

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