Combustion Characteristics of Solid Sustained-Release Energetic Materials

A solid sustained-release energetic material sample,an eruption device and a complete test system were prepared further to analyse the combustion characteristics of solid sustainedrelease energetic materials.The high-temperature heat flux generated by the combustion of the samples from the eruption device was used to penetrate the Q235 target plate.In addition,the meaning and calculation formula of energy density characterising the all-around performance of heat flux were proposed.The numerical simulation of the combustion effect of samples was carried out.According to the data comparison,the numerical simulation results agreed with the experimental results,and the maximum deviation between the two was less than 8.9%.In addition,the structure of the combustion wave and high-temperature jet was proposed and analysed.Based on theoretical analysis,experimental research and numerical simulation,the theoretical burning rate formula of the sample was established.The maximum error between the theoretically calculated mass burning rate and the experimental results was less than 9.8%.Therefore,using the gas-phase steady-state combustion model to study the combustion characteristics of solid sustained-release energetic materials was reasonable.The theoretical burning rate formula also had high accuracy.Therefore,the model could provide scientific and academic guidance for the theoretical research,system design and practical application of solid sustained-release energetic materials in related fields.

Fate of PM2.5-bound PAHs in Xiangyang, central China during 2018 Chinese spring festival: Influence of fireworks burning and air-mass transport

Variations of levels,possible source and air mass transmission were investigated for 16 USEPA priority-controlled PAHs in PM2.5 during 2018 Chinese Spring Festival(CSF)in Xiangyang City,central China which is the North-South pollutant airmass transport channel of China.Totally 37 samples were collected.Mass concentrations of 16 PAHs for the Pre–CSF day(Pre–CSFD),during the CSF day(CSFD)and after the CSF day(Af–CSFD)are 33.78±17.68 ng/m3,22.98±6.49 ng/m3,and 8.99±4.44 ng/m3,respectively.High resolution samples showed that 16 PAHs are higher in the morning(06:00–11:00)or afternoon(11:30–16:30),than those in the evening(17:00–22:00)and at night(22:30–05:30),whereas the result is reversed during the CSFD.Fireworks burning can obviously increase the mass concentration of PAHs.Air mass trajectory indicated that Xiangyang is a sink area of pollutants for northwest and southeast,and the sources of the northeast and southwest.The air mass only can be transmitted out through northeast and southwest.It is effective for improvement of air quality in Wuhan and Hunan to control fireworks emission in Henan and local areas.Fireworks burning was an important source for PAHs during CSFD,biomass,coal combustion,and traffic emission were the main sources of PAHs for Pre–CSFD and Af–CSFD periods.The health risk on the CSFD was higher than the acceptable levels,especially during the intensive fireworks burning,the risk value far exceed 1.0×10^-4,controlling burning fireworks is required.

Long-term medical treatment of patients with severe burns at exposed sites

BACKGROUND Body parts such as the face and hands are highly exposed during daily life and burns may accumulate in these areas.In addition,residual wounds,scar hyperplasia and contracture often exist in the late stage of a deep burn in these areas,which may affect patients’appearance,movements,and mental health.However,inadequate attention has been paid to this issue which can result in problems,such as difficulty in healing,possibility of carcinoma,chronic pain and a heavy mental burden.AIM To investigate the long-term medical treatment of patients with severe burns at exposed sites following a mass burn casualty event.METHODS A retrospective analysis of 13 patients with severe burns at exposed sites was performed to determine their respective long-term medical treatment.A combined wound dressing scheme consisting of traditional Chinese and Western medicine was introduced to repair residual wounds.Active and passive functional exercises with massage,Chinese herbal baths and compression fixation were proposed to ameliorate the condition of the hands.A combination of physical,chemical and photoelectrical measures was adopted for anti-scar treatment.A psychological intervention and recovery guide was provided which corresponded to the patients’psychological status.RESULTS Compared to patients who did not simultaneously receive the same treatment,patients who underwent systematic treatment recovered with a lower woundinfection rate(P<0.05),a shorter healing time(13.6±3.2 d)compared with(19.1±3.5 d)and more bearable pain during wound dressing at three days,one week and two weeks after a Chinese herbal bath(P<0.05).Satisfactory results were achieved with regard to restored function of patients’joints and blood supply to nerve endings,closure of the eyelids and the size of mouth opening tended to be normal,and only 7.1%of patients were diagnosed with severe scar hyperplasia and contracture deformity compared with 30.7%in the control group.In addition,the color,thickness,vascular distribution and softness score of the scars improved(P<0.01),and the effects of the psychological intervention was remarkable as shown by the Self-Rating Anxiety Scale and Self-Rating Depression Scale.CONCLUSION A better prognosis can be achieved in patients in the late stage of a burn with active residual wound repair,limb functional exercise,anti-scar and psychological rehabilitation.