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This study examines the effects of limb dominance and lead limb in task initiation on the kinetics and kinematics of step-off drop landings. Nineteen male participants performed drop landings led by the dominant and non-dominant limbs at 45-cm and 60-cm drop heights. Ground reaction force (GRF) and lower body kinematic data were collected. Between-limb time differences at the initial ground contact were calculated to indicate temporal asymmetry. Statistical Parametric Mapping (SPM) was applied for waveform analysis while two-way repeated measures ANOVA was used for discrete parameters. SPM results revealed greater GRF and lesser ankle dorsiflexion in the lead limb compared to the trail limb in 3 out of 4 landing conditions. The dominant limb displayed a greater forefoot loading rate (45 cm: p=.009, ηp2 = 0.438; 60 cm: p=.035, ηp2 = 0.225) and greater ankle joint quasi-stiffness (45 cm: p < .001, ηp2 = 0.360; 60 cm: p < .001, ηp2 = 0.597) than the non-dominant limb. Not all 380 trials were lead-limb first landings, with a smaller between-limb time difference (p=.009, d = 0.60) at 60 cm (4.1 ± 2.3 ms) than 45 cm (5.6 ± 2.7 ms). In conclusion, the step-off drop landing is not an ideal protocol for examining bilateral asymmetry in lower limb biomechanics due to potential biases introduced by limb dominance and the step-off limb.
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Articulación del Tobillo , Humanos , Masculino , Fenómenos Biomecánicos , Adulto Joven , Articulación del Tobillo/fisiología , Lateralidad Funcional/fisiología , Extremidad Inferior/fisiología , Adulto , Ejercicio PliométricoRESUMEN
Vitamin C (VC) possesses antioxidant and whitening effects. However, its effectiveness is hindered by challenges such as instability, impaired solubility, and limited bioavailability hinder. In this study, VC was encapsulated in nanoliposomes by primary emulsification and high-pressure homogenization. The VC nanoliposomes were comprehensively characterized for their microscopic morphology, particle size, polydispersity index (PDI), and encapsulation efficiency (EE). Orthogonal experiments were designed to optimize the optimal preparation process, and the antioxidant activity, whitening efficacy, transdermal absorption, and stability of VC nanoliposomes were evaluated based on this optimized process. The findings demonstrated the high reproducibility of the optimal process, with particle size, PDI, and EE values of 113.502 ± 4.360 nm, 0.104 ± 0.010, and 56.09 ± 1.01 %, respectively. Differential scanning calorimetry analysis showed effective encapsulation of VC nanoliposomes with better thermal stability than aqueous VC solution. Besides, the VC nanoliposomes demonstrated excellent antioxidant and whitening effects in efficacy experiments, stronger skin permeability in transdermal experiments and fluorescence tracking. Furthermore, storage stability tests indicated that the VC in nanoliposomes remained relatively stable after 60 days of storage. These findings highlighted the potential use of VC nanoliposomes in a wide range of applications for the cosmetic market, especially in the development of ingredients for skin care products.
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Proper pericarp thickness protects the maize kernel against pests and diseases, moreover, thinner pericarp improves the eating quality in fresh corn. In this study, we aimed to investigate the dynamic changes in maize pericarp during kernel development and identified the major quantitative trait loci (QTLs) for maize pericarp thickness. It was observed that maize pericarp thickness first increased and then decreased. During the growth and formation stages, the pericarp thickness gradually increased and reached the maximum, after which it gradually decreased and reached the minimum during maturity. To identify the QTLs for pericarp thickness, a BC4F4 population was constructed using maize inbred lines B73 (recurrent parent with thick pericarp) and Baimaya (donor parent with thin pericarp). In addition, a high-density genetic map was constructed using maize 10 K SNP microarray. A total of 17 QTLs related to pericarp thickness were identified in combination with the phenotypic data. The results revealed that the heritability of the thickness of upper germinal side of pericarp (UG) was 0.63. The major QTL controlling UG was qPT1-1, which was located on chromosome 1 (212,215,145-212,948,882). The heritability of the thickness of upper abgerminal side of pericarp (UA) was 0.70. The major QTL controlling UA was qPT2-1, which was located on chromosome 2 (2,550,197-14,732,993). In addition, a combination of functional annotation, DNA sequencing analysis and quantitative real-time PCR (qPCR) screened two candidate genes, Zm00001d001964 and Zm00001d002283, that could potentially control maize pericarp thickness. This study provides valuable insights into the improvement of maize pericarp thickness during breeding.
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Mapeo Cromosómico , Sitios de Carácter Cuantitativo , Zea mays , Sitios de Carácter Cuantitativo/genética , Zea mays/genética , Zea mays/anatomía & histología , Zea mays/crecimiento & desarrollo , Semillas/genética , Semillas/crecimiento & desarrollo , Semillas/anatomía & histología , Fenotipo , Cromosomas de las Plantas/genética , Polimorfismo de Nucleótido SimpleRESUMEN
In this paper, a high-quality germanene-polyvinyl alcohol (PVA) saturable absorber (SA) with a modulation depth of 3.05% and a saturation intensity of 17.95M W/c m 2 was prepared. Stable conventional mode-locking and harmonic mode-locking (HML) were achieved in germanene-based Er-doped fiber lasers (EDFL) using dispersion management techniques. In a cavity with a net dispersion value of -0.22p s 2, the conventional soliton had a center wavelength of 1558.2 nm, a repetition frequency of 19.09 MHz, and a maximum 3 dB spectrum bandwidth of 3.5 nm. The highest repetition frequencies achieved in cavities with net dispersion values of -2.81p s 2, -1.73p s 2, and -1.09p s 2 were 9.48 MHz, 12.75 MHz, and 12.10 MHz for HML, respectively. Furthermore, the effects of dispersion, power, and the polarization state on HML were systematically investigated. Our research results fully demonstrate the capability of germanene as an optical modulator in generating conventional mode-locked and harmonic mode-locked solitons. This provides meaningful references for promoting its application in ultrafast fiber lasers.
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Zeaxanthin is a naturally occurring xanthophyll carotenoid obtained from diet sources. Particularly, sweet corn is a major source of dietary zeaxanthin. To investigate the genetic basis of zeaxanthin content regulation in sweet corn, a recombinant inbred line (RIL) population comprising 191 families was constructed using two inbred lines (K44 and F22) with contrasting zeaxanthin content in the grain. The zeaxanthin content in the dry grains of this population grown at different locations was determined using high performance liquid chromatography (HPLC). Subsequently, 175 polymorphic simple sequence repeat (SSR) markers were used to construct a linkage map with a total length of 4322.37 cM and with an average distance of 24.4 cM. A total of eight QTLs located on chromosomes 4, 5, 7, 9, and 10 were detected. The QTLs located in umc1632-umc1401 on chromosome 7 were detected in different environments and explained 11.28-20.25% of the phenotypic variation, implying it is the main QTL controlling zeaxanthin content in the dry grains of sweet corn. Collectively, the present study provides a genetic map and theoretical guidance for the cultivation of sweet corn varieties with a high zeaxanthin content.
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Chronic ankle instability (CAI) is a prevalent condition characterized by recurring instances of the ankle giving way and persistent symptoms, including pain and diminished function. Foot and ankle external supports are commonly used in clinical practice and research for treating CAI. This systematic review aimed to assess the effects of foot and ankle external supports on the postural stability of individuals with CAI to guide clinical practice and inform future research. A comprehensive search was conducted in PubMed, Web of Science, Scopus, and Google Scholar databases from 1 January 2012 to 1 November 2022. Eighteen studies involving individuals with CAI were chosen in this systematic review. The quality of the included studies and risk of bias were assessed using Cochrane Collaboration's tool for randomized controlled trials, the Newcastle-Ottawa Scale for case-control studies, and the DELPHl-list for crossover trial studies. The external supports included in this review were ankle orthoses (elastic, semi-rigid, and active orthoses), taping (kinesiotaping and fibular reposition taping), and insoles (textured and supportive insoles). The outcome measures included static and dynamic postural stability tests, such as the single-leg stance test, star excursion balance test, Y-balance test, single-leg landing test, lateral jump test, walking test, and running test. The results showed that elastic orthoses, Kinesiotaping, and textured insoles demonstrated potential benefits in improving postural stability in individuals with CAI. Elastic orthoses decreased ankle joint motion variability, kinesiotaping facilitated cutaneous receptors and proprioceptive feedback, while textured insoles increased tactile stimulation and foot position awareness. However, the effects of semi-rigid orthoses, fibular reposition taping, and arch support insoles were inconsistent across studies. Future research should explore the long-term effects of these external supports, analyze the effects of different characteristics and combinations of supports, and employ standardized outcome measures and testing protocols for assessing postural stability.
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BACKGROUND: Functional ankle instability (FAI) is a common condition that affects individuals who have experienced previous ankle sprains. Textured insoles and elastic ankle braces have been previously used as interventions to improve stability in FAI patients. However, the optimal combination of these interventions has not been fully explored. The objective of this study was to investigate the effects of different types of textured insoles and elastic ankle braces on the dynamic stability of individuals diagnosed with FAI. METHODS: The study involved 18 FAI patients who performed single-leg landing tasks with and without wearing an eight-band elastic ankle brace while wearing textured insoles with protrusion heights of 0 mm, 1 mm, and 2 mm. The dynamic posture stability index (DPSI) and its components in the anterior-posterior (APSI), mediolateral (MLSI) and vertical (VSI) directions were calculated from the ground reaction force collected from the Kistler force plate during the first three seconds of the landing tasks. RESULTS: A significant interaction was found between textured insole type and ankle brace for DPSI (P = 0.026), APSI (P = 0.001), and VSI (P = 0.021). However, no significant interaction was observed for MLSI (P = 0.555). With elastic ankle braces, textured insoles with 1-mm protrusions significantly enhanced anterior-posterior, mediolateral, vertical, and overall stability compared to textured insoles with no and 2 mm protrusions (P < 0.05). Without elastic ankle braces, textured insoles with 1-mm protrusions significantly improved the anterior-posterior (P = 0.012) and overall stability (P = 0.014) of FAI patients compared to smooth insoles. CONCLUSIONS: The combination of textured insoles with 1-mm protrusion heights and an elastic ankle brace could enhance the dynamic stability of individuals with FAI, potentially mitigating the risk of ankle sprains.
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Traumatismos del Tobillo , Inestabilidad de la Articulación , Humanos , Tobillo , Tirantes , Articulación del Tobillo , Traumatismos del Tobillo/prevención & control , Inestabilidad de la Articulación/prevención & controlRESUMEN
Coupled photocatalysis without cocatalysts can maximize the utilization of photons and atoms, which puts forward higher demands on photocatalysts. Polymeric carbon nitride (CN) has become the most promising photocatalyst, but still suffers from major drawbacks of insufficient catalytic sites and low quantum efficiency. Herein, we report a fluid shear stress-assisted molecular assembly to prepare ultrathin-nanosheet-assembled acanthosphere-like CN (ASCN) with nitrogen vacancy (Nv) and carbonyl modification. Shear stress breaks the stacking interactions between layers and cuts the stacked structure into ultrathin layers, which are further reassembled into acanthosphere bundles driven by "centrifugal force". Benefitted greatly from the ultrathin nature that provides more exposed active sites and improves charge carrier separation, ASCN-3 exhibits a 20-fold higher activity than the bulk counterpart toward oxygen reduction to H2O2 coupled with 4-methoxybenzyl alcohol (4-MBA) oxidation to anisaldehyde (AA), with significantly increased turnover frequency (TOF) values (TOF: 1.69 h-1 for H2O2 and 1.02 h-1 for AA). Significantly, ASCN-3 exhibits 95.8% conversion for 4-MBA oxidation with nearly 100% selectivity. High apparent quantum yields of 11.7% and 9.3% at 420 nm are achieved for H2O2 photosynthesis and 4-MBA oxidation. Mechanism studies suggest that carbonyl induces holes concentrated at the neighboring melem unit to directly oxidize the Cα-H bond of 4-MBA to produce carbon radicals, and Nv as oxygen adsorption active site traps electrons to form a superoxide radical that further combines with the shed protons into H2O2. This work presents a simple physical method to break the layered stack of CN for creating hierarchical assembly for coupled photocatalysis.
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Background: Neurological disorders with dyskinesia would seriously affect older people's daily activities, which is not only associated with the degeneration or injury of the musculoskeletal or the nervous system but also associated with complex linkage between them. This study aims to review the relationship between motor performance and cortical activity of typical older neurological disorder patients with dyskinesia during walking and balance tasks. Methods: Scopus, PubMed, and Web of Science databases were searched. Articles that described gait or balance performance and cortical activity of older Parkinson's disease (PD), multiple sclerosis, and stroke patients using functional near-infrared spectroscopy were screened by the reviewers. A total of 23 full-text articles were included for review, following an initial yield of 377 studies. Results: Participants were mostly PD patients, the prefrontal cortex was the favorite region of interest, and walking was the most popular test motor task, interventional studies were four. Seven studies used statistical methods to interpret the relationship between motor performance and cortical activation. The motor performance and cortical activation were simultaneously affected under difficult walking and balance task conditions. The concurrent changes of motor performance and cortical activation in reviewed studies contained the same direction change and different direction change. Conclusion: Most of the reviewed studies reported poor motor performance and increased cortical activation of PD, stroke and multiple sclerosis older patients. The external motor performance such as step speed were analyzed only. The design and results were not comprehensive and profound. More than 5 weeks walking training or physiotherapy can contribute to motor function promotion as well as cortices activation of PD and stroke patients. Thus, further study is needed for more statistical analysis on the relationship between motor performance and activation of the motor-related cortex. More different type and program sports training intervention studies are needed to perform.
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The Daubert case in Philadelphia in 1999 caused a debate about the scientificity of fingerprint evidence. Since then, the current fingerprint identification system has been constantly challenged and questioned. Quantitative identification technology based on the statistics of fingerprint minutiae has become a new research hot spot. In this paper, an automatic detection algorithm is designed to achieve automatic classification of fingerprint minutiae using the deep convolution neural network YOLOv5 model. Then the occurrence frequencies of minutiae are statistically evaluated in 619,297 fingerprint images. The results show that the frequency ranges (unit%) of six types of minutiae per finger are ridge endings [68.49, 70.81], bifurcations [26.37, 27.26], independent ridges [1.533, 1.626], spurs [1.129, 1.198], lakes [0.4588, 0.4963], crossovers [0.3034, 0.3256]. The results also show that there are differences in the distribution frequency of the six types of minutiae in the ten finger positions ( thumb, middle, ring, index and little finger of the left and right hand) and in the four finger patterns ( arch, left loop, right loop and whorl). From the quantitative point of view of fingerprint identification, this paper calculates the number and frequency ranges of six types of minutiae, distinguishes the evaluation value of each type of minutiae, and provides the basic data support for establishing a probability model of fingerprint identification in the future.
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Algoritmos , Dermatoglifia , Redes Neurales de la Computación , Probabilidad , TecnologíaRESUMEN
An environmentally friendly mixed-halide perovskite MA3 Bi2 Cl9- x Ix with a bandgap funnel structure has been developed. However, the dynamic interfacial interactions of bandgap funneling in MA3 Bi2 Cl9- x Ix perovskites in the photoelectrochemical (PEC) system remain ambiguous. In light of this, single- and mixed-halide lead-free bismuth-based hybrid perovskites-MA3 Bi2 Cl9- y Iy and MA3 Bi2 I9 (named MBCl-I and MBI)-in the presence and absence of the bandgap funnel structure, respectively, are prepared. Using temperature-dependent transient photoluminescence and electrochemical voltammetric techniques, the photophysical and (photo)electrochemical phenomena of solid-solid and solid-liquid interfaces for MBCl-I and MBI halide perovskites are therefore confirmed. Concerning the mixed-halide hybrid perovskites MBCl-I with a bandgap funnel structure, stronger electronic coupling arising from an enhanced overlap of electronic wavefunctions results in more efficient exciton transport. Besides, MBCl-I's effective diffusion coefficient and electron-transfer rate demonstrate efficient heterogeneous charge transfer at the solid-liquid interface, generating improved photoelectrochemical hydrogen production. Consequently, this combination of photophysical and electrochemical techniques opens up an avenue to explore the intrinsic and interfacial properties of semiconductor materials for elucidating the correlation between material characterization and device performance.
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Purpose: Shoelace tightness is an important factor that may influence basketball players' performance and injury risk during shuttle slip movement. This study aimed to examine the effects of shoelace tightness on shoelace tension, lower limb kinematics and kinetics, and subjective perception in basketball players. Methods: Sixteen male college basketball players performed lateral shuffle movements with their dominant foot landing on a force plate under three shoelace tightness conditions (loose, comfortable and tight). A motion capture system and a force plate were used to measure lower limb kinematics and kinetics, respectively. A customized wireless shoelace tension system was used to measure shoelace tension at three locations on the dorsum of the foot. Visual analogue scales were used to assess perceived comfort, foot pressure and in-shoe displacement. Results: Shoelace tension increased with shoelace tightness (loose: 13.56 ± 6.21 N, comfortable: 16.14 ± 5.35 N, tight: 21.25 ± 6.19 N) and varied with shoelace position (front: 20.19 ± 5.99 N, middle: 13.71 ± 5.59 N, rear: 17.04 ± 6.95 N). Shoelace tightness also affected some of the ankle joint kinematics and kinetics as well as the subjective ratings of foot pressure and in-shoe displacement ( p < 0.05). The loose shoelace increased the ankle inversion angle, while the comfortable shoelace decreased the knee negative power. The tight shoelace increased the perceived foot pressure and reduced the inshoe movement ( p < 0.05). Conclusions: Shoelace tightness could significantly affect lower limb biomechanics and subjective perception during lateral shuffle in basketball. Basketball footwear designers should consider the incorporation of multiple shoelaces or zonal lacing systems to allow athletes to fine-tune the tension across different areas of the foot.
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Baloncesto , Extremidad Inferior , Humanos , Baloncesto/fisiología , Masculino , Fenómenos Biomecánicos , Extremidad Inferior/fisiología , Adulto Joven , Zapatos , Movimiento/fisiología , Percepción/fisiología , Presión , CinéticaRESUMEN
Pericarp thickness affects the edible quality of sweet corn (Zea mays L. saccharata Sturt.). Therefore, breeding varieties with a thin pericarp is important for the quality breeding of sweet corn. However, the molecular mechanisms underlying the pericarp development remain largely unclear. We performed an integrative analysis of mRNA and miRNA sequencing to elucidate the genetic mechanism regulating pericarp thickness during kernel development (at 15 days, 19 days, and 23 days after pollination) of two sweet corn inbred lines with different pericarp thicknesses (M03, with a thinner pericarp and M08, with a thicker pericarp). A total of 2,443 and 1,409 differentially expressed genes (DEGs) were identified in M03 and M08, respectively. Our results indicate that phytohormone-mediated programmed cell death (PCD) may play a critical role in determining pericarp thickness in sweet corn. Auxin (AUX), gibberellin (GA), and brassinosteroid (BR) signal transduction may indirectly mediate PCD to regulate pericarp thickness in M03 (the thin pericarp variety). In contrast, abscisic acid (ABA), cytokinin (CK), and ethylene (ETH) signaling may be the key regulators of pericarp PCD in M08 (the thick pericarp variety). Furthermore, 110 differentially expressed microRNAs (DEMIs) and 478 differentially expressed target genes were identified. miRNA164-, miRNA167-, and miRNA156-mediated miRNA-mRNA pairs may participate in regulating pericarp thickness. The expression results of DEGs were validated by quantitative real-time PCR. These findings provide insights into the molecular mechanisms regulating pericarp thickness and propose the objective of breeding sweet corn varieties with a thin pericarp.
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With the development of volleyball technology, the frequent competition, the fierce competition, and the increase of sports load, the requirements for the athletes' own body, intelligence, combat, heart, and skills are getting higher and higher. Volleyball is one of the most popular sports in the world. It attracts people all over the world with its strong team appeal and its own unique charm. This study mainly discusses the characteristics of shoulder joint dysfunction in volleyball players and the effect of rehabilitation training under the background of artificial intelligence. By sorting out the development process of artificial intelligence technology, it can be analyzed that artificial intelligence technology already has a certain knowledge reserve, can make corresponding mechanized feedback, and can make correct judgments based on experience in more complex situations. This study compared volleyball athletes with handicap and barrier-free shoulder joints and observed the characteristics of shoulder pain, stability, and flexibility caused by subacromial impingement syndrome. It also looked at whether subacromial impingement syndrome athletes differ in volleyball spiking sequence and mobilization and recruitment of muscle power during swing spikes compared to athletes with normal shoulder function in the full kinetic chain. According to the volleyball intelligent competition platform, the implementation and application of ideas such as data collection, result feedback, adjustment of training plan, implementation of training plan, and real-time monitoring are regularly monitored. On the one hand, through timely assessment and detection of shoulder function of volleyball players, functional training is carried out for weaknesses to prevent injury; on the other hand, after a mild injury occurs, timely targeted training should be taken to find and correct wrong actions, and strengthen the weak part of muscle strength, so as to reduce the probability of repeated injury and improve sports performance and athletic ability. In the new system, after collecting and sorting, testers can directly upload to the web page in the form of Excel for automatic filling, grasp the test information of athletes in time, generate automatic warning, and save time. The monitoring content determined by this study mainly includes three index systems, including load, training preparation performance, and recovery. According to the self-provided evaluation system of relevant test equipment and the experience of expert coaches, the evaluation standards for each index are formulated. There was a statistically significant difference in the scores between the rehabilitation group and the pre-rehabilitation group during the study (P < 0.05). This study attempts to find the characteristics and rules of FMS scores of women's volleyball players of different levels, so as to provide more targeted physical training for volleyball players, promote the all-round development of physical fitness, and avoid the risk of sports injuries. This study provides more effective and comprehensive recommendations for the prevention and recovery of shoulder injuries in volleyball players. This study provides more effective and comprehensive recommendations for the prevention and recovery of shoulder injuries in volleyball players. The results of the study can provide reference for the scientific training and rehabilitation of volleyball players and make suggestions for the treatment and prevention of subacromial impingement syndrome.
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Síndrome de Abducción Dolorosa del Hombro , Lesiones del Hombro , Articulación del Hombro , Voleibol , Inteligencia Artificial , Femenino , Humanos , Voleibol/fisiologíaRESUMEN
The photocatalytic system using hydrohalic acid (HX) for hydrogen production is a promising strategy to generate clean and renewable fuels as well as value-added chemicals (such as X2 /X3 - ). However, it is still challenging to develop a visible-light active and strong-acid resistive photocatalyst. Hybrid perovskites have been recognized as a potential photocatalyst for photovoltaic HX splitting. Herein, a novel environmentally friendly mixed halide perovskite MA3 Bi2 Cl9-x Ix with a bandgap funnel structure is developed, i.e., confirmed by energy dispersive X-ray analysis and density functional theory calculations. Due to gradient neutral formation energy within iodine-doped MA3 Bi2 Cl9 , the concentration of iodide element decreases from the surface to the interior across the MA3 Bi2 Cl9-x Ix perovskite. Because of the aligned energy levels of iodide/chloride-mixed MA3 Bi2 Cl9-x Ix , a graded bandgap funnel structure is therefore formed, leading to the promotion of photoinduced charge transfer from the interior to the surface for efficient photocatalytic redox reaction. As a result, the hydrogen generation rate of the optimized MA3 Bi2 Cl9-x Ix is enhanced up to ≈341 ± 61.7 µmol h-1 with a Pt co-catalyst under visible light irradiation.
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Color tunability of perovskite light-emitting diodes (PeLEDs) by mixed halide compositional engineering is one of the primary intriguing characteristics of PeLEDs. However, mixed halide PeLEDs are often susceptible to color red-shifting caused by halide ion segregation. In this work, strongly quantum-confined perovskite nanowires (QPNWs) made of CsPbBr3 are grown in nanoporous anodic alumina templates using a closed space sublimation process. By tuning the pore size with atomic layer deposition, QPNWs with a diameter of 6.6 to 2.8 nm have been successfully obtained, with continuous tunable photoluminescence emission color from green (512 nm) to pure blue (467 nm). To better understand the photophysics of QPNWs, carrier dynamics and the benefit of alumina passivation are studied and discussed in detail. Eventually, PeLEDs using various diameters of CsPbBr3 QPNWs are successfully fabricated with cyan color (492 nm) PeLEDs, achieving a record high 7.1% external quantum efficiency (EQE) for all CsPbBr3-based cyan color PeLEDs. Sky blue (481 nm) and pure blue (467 nm) PeLEDs have also been successfully demonstrated, respectively. The work here demonstrates a different approach to achieve quantum-confined one-dimensional perovskite structures and color-tunable PeLEDs, particularly blue PeLEDs.
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The purpose of this study was to investigate the effects of surface slope and body posture (i.e., seated and standing) on lower extremity joint kinetics during cycling. Fourteen participants cycled at 250 watts power in three cycling conditions: level seated, uphill seated and uphill standing at a 14% slope. A motion analysis system and custom instrumented pedal were used to collect the data of fifteen consecutive cycles of kinematics and pedal reaction force. One crank cycle was equally divided into four phases (90° for each phase). A two-factor repeated measures MANOVA was used to examine the effects of the slope and posture on the selected variables. Results showed that both slope and posture influenced joint moments and mechanical work in the hip, knee and ankle joints (p < 0.05). Specifically, the relative contribution of the knee joint to the total mechanical work increased when the body posture changed from a seated position to a standing position. In conclusion, both surface slope and body posture significantly influenced the lower extremity joint kinetics during cycling. Besides the hip joint, the knee joint also played the role as the power source during uphill standing cycling in the early downstroke phase. Therefore, adopting a standing posture for more power output during uphill cycling is recommended, but not for long periods, in view of the risk of knee injury.
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Ciclismo , Postura , Articulación del Tobillo , Humanos , Cinética , Articulación de la RodillaRESUMEN
Bicycle saddle height configurations have been shown to affect knee joint biomechanics. Research suggests that an excessively low saddle height may lead to Patellofemoral Pain Syndrome, which is thought to be caused by the knee adduction moment during cycling. However, how saddle heights affect frontal plane knee biomechanics was not clear. We aimed to compare different saddle heights on frontal plane knee biomechanics during cycling. Twenty healthy young recreational cyclists (23.4 ± 0.5 years) performed 3 min of cycling at four different saddle heights (Medium [25° knee flexion angle], Preferred [a height chosen by cyclists], Low [Preferred + 15°], High [Preferred - 15°] measured at the bottom-dead-center). Cycling workload and cadence were set at 60 w and 60 RPM, respectively, since our project was focused on rehabilitation. A motion analysis system and a custom instrumented pedal were used to collect three-dimensional kinematics d (200â Hz) and pedal reaction force (1000â Hz). Results showed that, compared with other saddle heights, Low saddle height produced greater adduction knee moments (11.9 ± 1.9 Nm, P < 0.05), a longer duration (0.15 ± 0.01 s, P < 0.05), larger knee flexion (58.5 ± 2.6°, P < 0.05) and larger abduction angles (-4.5 ± 0.8°, P < 0.05). We showed that Low saddle height resulted in increased knee adduction moments with longer duration. In contrast, High saddle height reduced both knee moments and time duration. The results suggest that increased saddle heights may provide a safe and efficient cycling strategy for healthy young recreational cyclists.
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Ciclismo/fisiología , Diseño de Equipo , Articulación de la Rodilla/fisiología , Equipo Deportivo , Adulto , Fenómenos Biomecánicos , Femenino , Voluntarios Sanos , Humanos , Masculino , Adulto JovenRESUMEN
Detecting gait events from video data accurately would be a challenging problem. However, most detection methods for gait events are currently based on wearable sensors, which need high cooperation from users and power consumption restriction. This study presents a novel algorithm for achieving accurate detection of toe-off events using a single 2D vision camera without the cooperation of participants. First, a set of novel feature, namely consecutive silhouettes difference maps (CSD-maps), is proposed to represent gait pattern. A CSD-map can encode several consecutive pedestrian silhouettes extracted from video frames into a map. And different number of consecutive pedestrian silhouettes will result in different types of CSD-maps, which can provide significant features for toe-off events detection. Convolutional neural network is then employed to reduce feature dimensions and classify toe-off events. Experiments on a public database demonstrate that the proposed method achieves good detection accuracy.
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Black TiO2 containing Ti(3+) attracts enormous attention due to its excellent visible-light driven photocatalytic activity. Herein, an in situ thermal decomposition approach to synthesize uniform thin carbon coated Ti(3+)-TiO2 nanocrystals is presented. During the oleic acid-assisted solvothermal process, the crystal size and morphology of TiO2 were controlled through oleic acid with carboxylic acid groups. Then the residual small quantities of oleic acid anchored on TiO2 were used as a carbon source, which could be in situ pyrolyzed into a carbon layer on TiO2 at high temperature and under an inert atmosphere. Meanwhile, Ti(4+) species were partly reduced into Ti(3+) states/oxygen vacancies on the surface of TiO2 due to the carbothermal reduction reaction for the carbon-encapsulated Ti(3+)-TiO2 structure. A series of characterizations indicated that the 20-25 nm TiO2 nanocrystals obtained were wrapped evenly by 1-2 nm carbon layers, which had an important effect on the energy band structure change of TiO2. The presence of the carbon layer also improves the Ti(3+) stability and the conduction behavior of the composites. The Ti(3+) states/oxygen vacancies created on the surface of TiO2 were responsible for the remarkable photogenerated charge separation and extended visible-light absorption range. Furthermore, Ti(3+) states/oxygen vacancies and the carbon layer together could enhance the adsorption ability of O2 so as to promote the photogenerated electrons captured by the adsorbed O2, leading to a great increase in the charge separation. As a result, the composites exhibit high photocatalytic performance for organic pollutants under visible light irradiation. This simple and new method may pave the way to practical applications for efficient photocatalytic degradation under visible light.