Dynamic evolution of low-viscosity fuel particle distribution driven by constant flow

The effects of mass concentration and injection pressure on the atomization characteristics of low-viscosity fuel spray are studied in a constant-volume chamber.Microscopic spray parameters are measured by laser diffraction at different axial and radial positions downstream of the nozzle.The results show that the atomization effect is inhibited linearly with the increase of mass concentration.The increase of injection pressure promotes the droplet breakup.However,the trend gradually weakens and becomes more noticeable at high concentrations.Comparing with the concentration,the influence of the injection pressure on the atomization characteristics is dominant.Although low concentration and high injection pressure can promote the droplet breakup,they also increase the probability of droplet collision,resulting in droplet aggregation.This is more evident in low-viscosity fuels.The droplet size increases in the axial direction owing to the aggregation.However,the diameter decreases in the radial direction owing to the outward deflection of small droplets caused by air turbulence and entrainment.In addition,the high-velocity airflow significantly promotes the droplet breakup near the nozzle and spray axis regions and inhibits the aggregation effect.However,the lower-viscosity fuels keep smaller droplet sizes and better atomization in the whole spraying process,which is easier to realize than the higher-viscosity fuels.Overall,low concentration,high injection pressure,and low viscosity of fuel have beneficial effects on the droplet breakup.This is very important for improving the atomization effect of fuel.

PPARs： diverse regulators in energy metabolism and metabolic diseases

原子受体 PPAR 为精力动态平衡是根本上重要的。通过他们的不同还重叠的功能和织物分发， PPAR 在 transcriptional 水平调整精力新陈代谢的许多方面。这些受体的功能的缺陷或 dysregulation 导致许多新陈代谢的疾病，当时他们的 ligands 提议许多新陈代谢的好处。这些受体的研究推进了我们精力新陈代谢的 transcriptional 基础的知识并且帮助了我们理解新陈代谢的症候群的病原的机制。

Electrostaticspray preparation and properties of RDX/DOS composites

A composite explosive based on 1,3,5-trinitro-1,3,5-triazinane(RDX)was prepared by electrostaticspray method with dioctyl sebacate(DOS)as desensitizer.After preparation,the particle size and crystal structure were characterized and chemical features,such as chemical bonds,functional groups,thermal decomposition parameters and mechanical sensitivity were investigated as well.In terms of the morphologies of the composites,the particle sizes were in the range of 1e3 mm.Compared with RDX,the crystal types,chemical bonds and functional groups of the RDX/DOS composites were unchanged.The activation energy of the composites was lower than that of raw RDX,and the 3wt%DOS composites had the lowest activation energy.The impact sensitivity and friction sensitivity of the RDX/DOS composites were lower than those of raw RDX,and the 10wt%DOS composites had the highest H50(125.9 cm)and the lowest friction sensitivity(8%).

Effect of metal powders on explosion of fuel-air explosives with delayed secondary igniters

In order to improve the energy level of fuel air explosive(FAE) with delayed secondary igniters, high energetic metal powders were added to liquid fuels mainly composed of ether and isopropyl nitrate.Metal powders’ explosive properties and reaction mechanisms in FAE were studied by high-speed video,pressure test system, and infrared thermal imager. The results show that compared with pure liquid fuels, the shock wave overpressure, maximum surface fireball temperature and high temperature duration of the mixture were significantly increased after adding high energetic metal powder. The overpressure values of the liquid-solid mixture at all measuring points were higher than that of the pure liquid fuels. And the maximum temperature of the fireball was up to 1700C, which was higher than that of the pure liquid fuels. After replacing 30% of aluminum powder with boron or magnesium hydride, the shock wave pressure of the mixture was further increased. The high heat of combustion of boron and the hydrogen released by magnesium hydride could effectively increase the blast effect of the mixture. The improvement of the explosion performance of boron was better than magnesium hydride. It shows that adding high energetic metal powder to liquid fuels can effectively improve the explosion performance of FAE.

Chemical composition and morphology of apple cuticular wax during fruit growth and development

Abstract Cuticular wax covers the surface of the apple epidermis and plays an important role in water loss and pathogen resistance.However,little is known about wax biosynthesis during apple fruit development.In this study,the morphological structure and chemical composition of wax and the transcription patterns of wax-related genes were investigated in the'Red Delicious'and'Golden Delicious'cultivars.The results showed that accumulation of the waxy layer was synchronized with enlargement and maturation of fruit.The crystal structure,major chemical components(very long chain fatty acids and triterpenes)of wax and the expression levels of wax-related genes varied significantly 90 days after flowering(DAF),indicating that the critical period for biosynthesis of cuticular wax was about 90 DAF.This finding is valuable for further study of the regulatory mechanism of wax biosynthesis at both the molecular and physiological levels.