One-step green method to prepare progressive burning gun propellant through gradient denitration strategy

Gradiently denitrated gun propellant(GDGP)prepared by a“gradient denitration”strategy is obviously superior in progressive burning performance to the traditional deterred gun propellant.Currently,the preparation of GDGP employed a tedious two-step method involving organic solvents,which hinders the large-scale preparation of GDGP.In this paper,GDGP was successfully prepared via a novelty and environmentally friendly one-step method.The obtained samples were characterized by FT-IR,Raman,SEM and XPS.The results showed that the content of nitrate groups gradiently increased from the surface to the core in the surface layer of GDGP and the surface layer of GDGP exhibited a higher compaction than that of raw gun propellant,with a well-preserved nitrocellulose structure.The denitration process enabled the propellant surface with regressive energy density and good progressive burning performance,as confirmed by oxygen bomb and closed bomb test.At the same time,the effects of different solvents on the component loss of propellant were compared.The result showed that water caused the least component loss.Finally,the stability of GDGP was confirmed by methyl-violet test.This work not only provided environmentally friendly,simple and economic preparation of GDGP,but also confirmed the stability of GDGP prepared by this method.

Metal chelation reduces skin epithelial inflammation and rescues epithelial cells from toxicity due to thermal injury in a rat model

Background:One of the most pervasive complications of burn injury is wound progression,characterized by continuous tissue destruction in untreated wounds,which leads to wound infection,inflammation,oxidative stress and excessive scar formation.We determined whether additional tissue destruction could be attenuated with Livionex formulation(LF)lotion,which contains a metal-chelating agent and reduces inflammation in burn wounds.Methods:We subjected male Sprague Dawley rats to a 2%total body surface area(TBSA)burn using a brass comb model and topically applied LF lotion(containing ethylenediaminetetraacetic acid and methyl sulfonyl methane)to the affected area every 8 hours over 3 days.Inflammatory cytokine levels,cell apoptosis and wound healing were compared in LF lotion-treated and untreated rats.Statistical analysis was performed using a one-way analysis of variance in conjunction with Tukey’s post-hoc test.Results:Serum inflammatory cytokines were not detectable after 3 days,suggesting that small burn wounds induce only an immediate,localized inflammatory response.Microscopy revealed that LF lotion improved burn site pathology.Deoxynucleotidyl transferase biotin-d-UTP nick-end labeling staining showed reduced cell death in the LF-treated samples.LF lotion prevented the spread of tissue damage,as seen by increased amounts of Ki-67-positive nuclei in the adjacent epidermis and hair follicles.Tumor necrosis factor-alpha,interleukin-6 and inducible nitric oxide synthase levels in LF-treated skin sections from burned rats were comparable to the levels observed in unburned control sections,indicating that LF lotion reduces inflammation in and around the burn site.Conclusions:These results establish LF lotion as a therapeutic agent for reducing inflammatory stress,cell death and tissue destruction when applied immediately after a burn injury.Further studies of LF lotion on large TBSA burns will determine its efficacy as an emergency treatment for reducing long-term morbidity and scarring.