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Objective: Biomechanical methods were used to explore the influence of age and gender on children’s motor characteristics, and the internal muscle strength were calculated through simulation modeling, so as to provide ideas for the screening of children with diseases and promotion of motor development. Method: BTS motion capture system collects kinematics data; Kistler force platform collects dynamic data, the simulation software(Anybody 5.2)calculates the muscle strength of the lower limb, two-way ANOVA was performed for difference test. Results: gait: SB, SD, SDI and TA muscle strength increased gradually. GMIP muscle strength: 4 years old group is greater than 3-years-old group. SDI and TFL strength: boys’ were greater than girls’. Running: GM muscle strength: boys’ are greater than girls’. PB muscle strength: the 3-year-old group has smallest muscle strength. GMAS muscle strength: the 3-year-old group has the largest muscle strength, boys’ are greater than girls’. Conclusions: (1) Walking: At the striking time, the buffering capacity of ankle is enhanced gradually. At the moment of lifting off the ground, the range of ankle stretching increased gradually, The angular velocity characteristics has a gender difference. The development of hip flexor muscle strength was uneven between boys and girls. The cushioning muscle strength of the ankle was greater in the 5-year-old group.(2) There were gender differences in time parameters of running. The flexion angle of the ankle was larger at the striking time, which was related to different striking patterns. At the time off-the-ground, the 5-year-old group had the largest hip extension angle. Younger children used more frontal plane joint movement and more hip abductor force.

(NH4)2RuCl6is an important precursor in the synthesis of Ru powder with high-purity requirement. In this study, high-purity (>99.999 wt%) micro-sized (NH4)2RuCl6pieces were synthesized by distillation and precipitation from crude Ru powder. Then, the thermal decomposition behavior of the (NH4)2RuCl6pieces was investigated. The decomposition process included two stages. First, (NH4)2RuCl6was decomposed from 255.0°C to 314.0°C, with the endothermic peak located at 309.4°C. At this stage, HCl and NH3were released, while the dense micro-pieces were transformed to loosened micro-pieces due to the thermal decomposition. Then, the solid phase [(NH3)4Ru3Cl12] kept decomposing from 314.0°C to 352.7°C, HCl and N2were released, and agglomerated Ru particles were achieved. Thermogravimetric analysis-differential thermal analysis-mass spectrum coupling (TG-DTA-MS) was used to monitor the thermal decomposition process and identify the released gaseous phases, respectively. The solid phases in different stages were characterized by high-temperature X-ray diffraction (HTXRD). A good understanding of the processing and thermal decomposition of (NH4)2RuCl6is crucial in the creation of Ru products.

(NH 4 ) 2 RuCl 6 is one of the most important precursors for the preparation of Ru powder with high-purity requirement. In this study, high-purity (> 99.999 wt%) micro-spherical (from 2.3 to 10.4 μm) (NH 4 ) 2 RuCl 6 particles with controllable surface were synthesized by chemical separation method combined with spray drying process. After the chemical separation, high-purity (NH 4 ) 2 RuCl 6 precipitation was achieved, while the morphology, size and surface of (NH 4 ) 2 RuCl 6 particles were controlled by the spray drying process. The detailed influencing mechanisms of spray drying process, including gas/liquid rate, drying temperature and solution concentration, were investigated. Both gas/liquid rate and drying temperature influence the morphology and size of spray dried particles, while solution concentration is directly proportional to size of spray dried particles. It should be noted that the powder technology in this study could be applied to synthesize other high-purity spherical particles.

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. Graphical abstract .