Effects of Task Interference on Kinematics and Dual-Task Cost of Running in Early Childhood.

Children aged 3-8 are in a critical period for motor development and postural control. Running is a basic motor skill that children need to master in early childhood. While running, children are prone to dangerous events such as falls. This study investigates the kinematic characteristics of running by children associated with different interference tasks, i.e., normalized running, cognitive dual-tasks, and obstacle crossing tasks, and provides a theoretical foundation for the interference mechanism of children's dynamic postural control and for screening of motor disorders. Two hundred children aged 3-8 were recruited. The BTS Bioengineering infrared motion capture system was used to collect spatiotemporal and kinematic running data under three tasks. Repeated measures of variance analysis were used to compare the effects of different interference tasks and ages on children's running signs. The main and interaction effect tests were compared by the Bonferroni method. The results and conclusions are as follows: (1) Running characteristics of early childhood are influenced by interference tasks and age. With interference tasks, the overall characteristics of running by children aged 3-8 showed an increasing trend in running cycle time and a decreasing trend in stride length, step length, cadence, and speed. (2) Both cognitive and obstacle crossing tasks had costs, and cognitive task costs were greater than obstacle crossing costs. Children adopted a "task first" running strategy with different interference tasks. When facing cognitive tasks, their overall joint motion decreased, and they reduced joint motions to promote task completion. When facing obstacle crossing tasks, because of the characteristics of the task itself, children increased joint motions to cope with interference. (3) In terms of age, the running characteristics showed a nonlinear development trend in various indicators, with a degree of recurrence and high variability in adjacent age groups. (4) The dual-task interference paradigm of "postural-cognition" can be used as a motor intervention tool to promote the development of basic motor skills in early childhood.

Facile and General Method to Synthesize Pt-Based High-Entropy-Alloy Nanoparticles.

Pt-based high-entropy-alloy nanoparticles (HEA-NPs) have excellent physical and chemical properties due to the diversity of composition, complexity of surface structure, high mixing entropy, and properties of nanoscale, and they are used in a wide range of catalytic applications such as catalytic ammoxidation, the electrolysis of water to produce hydrogen, CO2/CO reduction, and ethanol/methanol oxidation reaction. However, offering a facile, low-cost, and large-scale method for preparing Pt-based HEA-NPs still faces great challenges. In this study, we employed a spray drying technique combined with thermal decomposition reduction (SD-TDR) method to synthesize a single-phase solid solution from binary nanoparticles to denary Pt-based HEA-NPs containing 10 dissimilar elements loaded on carbon supports in an H2 atmosphere with a moderate heating rate (3 °C/min), thermal decomposition temperature (300-850 °C), duration time (30 min), and low cooling rate (5-10 °C/min). The Pt autocatalytic behavior was found and investigated, confirming that Pt element could decrease the reduction temperature of other metals via autocatalytic behavior. Therefore, using the feature of Pt autocatalytic behavior, we have achieved Pt-based HEA-NPs at a minimum temperature of 300 °C. We not only prepared a series of Pt-based HEA-NPs with targetable ingredient, size, and phase using the SD-TDR method but also proved the expandability of the SD-TDR technique by synthesizing Pt-based HEA-NPs loaded on different supports. Moreover, we investigated methanol oxidation reaction (MOR) on as-synthesized senary PtCoCuRuFeNi HEA-NPs, which presented superior electrocatalytic performance over commercial Pt/C catalyst.

Biomechanical Characteristics of Vertical Jumping of Preschool Children in China Based on Motion Capture and Simulation Modeling.

Vertical jumping is one of the basic motor skills, and it is an essential part of many sports. The main purpose of this paper is to investigate characteristics of vertical jumping of children. This paper uses a motion capture system, three-dimensional platforms, and a simulation modeling system to analyze the kinematics and dynamics performance of children's vertical jumping. The compression time increases from 3 to 4 years old, and flight height and time increases with age and stage gradually. In the compression phase and pushing phase, the hip and knee joint play a major role; in the landing phase, the knee and ankle joint play a major role. Muscle forces are mainly affected by age, and the three types of muscle force had two different trends. The muscle force of the shank and thigh increased with age, and the pelvic girdle muscles showed an "low-high-low" trend. The regression model suggests that the force of GMiP and the hip angular velocity have a great influence on jumping ability. Therefore, if we want to improve the jumping ability of preschool children, we should pay more attention to hip exercises. We should integrate the hip exercises into interesting games, which are more in line with their physical and mental health.

Impact of situational sport games on gross movements and social development among children aged 4-5 years old / 中国学校卫生

Objective@#To explore the impact of situational sport games on gross movement and social development among children aged 4-5 years, and to provide references for promoting the healthy development of preschool children.@*Methods@#Seventy one children aged 4-5 were randomly selected from one public kindergarten in Beijing during Apr. to Jul. of 2019 and were randomly divided into experimental group ( n =36, 8 week situational sports game intervention) and control group ( n =35, regular learning and playing). The Test of Gross Motor Development (TGMD-3) and social development scale for children aged 3-9 were used to assess gross movement and social development, respectively, which were then compared and analyzed.@*Results@#Before intervention, the total score of gross motor development[intervention group (42.63±7.62), control group (43.00±9.16)] and social development[intervention group (211.88±6.68), control group (212.71±9.80)] showed no significant differences between the two groups( t =-0.18，-0.37， P >0.05). After intervention, increases in gross motor development[intervention group (67.80±9.80), control group (45.68±9.47)] and social development level[intervention group (228.30±6.37), control group (214.71±8.65)] were observed in both groups( t =25.82，3.22；15.90，2.13， P <0.05), with gross movement and social development scores higher in intervention group than that of the control group( t =9.66，7.54， P <0.05).@*Conclusion@#8 week situational sports games can promote gross movement and social development of 4-5 year old children. It is suggested that interventions to promote early childhood development should be aware of multiple dimensions of development.

Synthesis of PtCoNiRu/C nanoparticles by spray drying combined with reduction sintering for methanol electro-oxidation.

The controllable synthesis of carbon-supported platinum-based multicomponent alloys is important for the development and application of direct methanol fuel cells (DMFCs). In this paper, controllable synthesis of carbon-supported PtCoNiRu quaternary alloy is realized by spray drying and reduction sintering. The effects of reduction temperature on the size, morphology and catalytic properties of the metal nanoparticles were investigated. The electrochemical performance of the as-synthesized PtCoNiRu/C catalysts towards methanol electro-oxidation was studied using cyclic voltammetry (CV) and chronoamperometry. The results show that metal nanoparticles with uniform size and dispersity on the carbon surface can be obtained at a suitable sintering temperature, while the catalyst has a higher electrochemical active surface area (ECSA) and shows better catalytic activity and stability for methanol electro-oxidation. The method described in this study provides a new route for the manufacture of Pt alloy nanoparticles with higher catalytic activity and stability.

Correction to: Synthesis and Characterization of Nanoscale Tungsten Particles with Hollow Superstructure Using Spray Drying Combined with Calcination Process.

In the article [1], the use of the formula (NH4)6W7O24·6H2O to represent the starting material ammonium paratungstate (APT) is outdated and incorrect.

Synthesis and Characterization of Nanoscale Tungsten Particles with Hollow Superstructure Using Spray Drying Combined with Calcination Process.

Nanoscale tungsten (W) powder is used in some special materials. In this study, a hollow superstructure W powder consisting of nanoparticles was synthesized by spray drying combined with two-step calcination from commercial (NH4)6W7O24·6H2O. The high-pressure gas (HPG) was the significant factor in spray drying process, which affect the BET surface area and average particles size of the spray-dried powders. The detailed influences of calcined steps and calcination temperature in the microstructure and average particles size of final W particles were investigated. The size distribution of as-synthesized nanoscale W particles with hollow superstructure was from 40 to 200 nm, and the average size was about 100 nm. The as-synthesized W powder shows good sintering properties. It should be noted that the powder technology in this study can be used to synthesize other powders with high-performance requirements. .