Dissolution of a new explosive formulation containing TNT and HMX : Comparison with octol

GIM (Greener Insensitive Material) is a new explosive formulation made of HMX(51.5%), TNT (40.7%), and a binder, ETPE (7.8%), which is currently investigated by the Canadian Department of National Defense for a wider use by the Army. In the present study, dissolution of GIM in water was measured and compared to the dissolution of octol (HMX/TNT: 70/30). Although the presence of ETPE did not prevent completely TNT and HMX from dissolving, GIM appeared to dissolve more slowly than octol. The ETPE was shown to prevent the formulation particles from collapsing and to retard the dissolution of both TNT and HMX by limiting their exposure to water. In both octol and GIM, the dissolution rate of the particles was governed by the compound(s) that are slower to dissolve, i.e. HMX in octol, and HMX and ETPE in GIM. A model based on Fick\u2019s diffusion law allowed fitting well the dissolution data of octol but was less appropriate to fit the data of GIM likely due to a physical rearrangement of the solid upon dissolution. The present findings demonstrate that ETPE in GIM decreases the risks of explosives leakage from particles of the new formulation and should facilitate the collecting of non-exploded GIM particles in training sites.Peer reviewed: YesNRC publication: Ye

Fate of CL-20 in sandy soils : Degradation products as potential markers of natural attenuation

Hexanitrohexaazaisowurtzitane (CL-20) is an emerging explosive that may replace the currently used explosives such as RDX and HMX, but little is known about its fate in soil. The present study was conducted to determine degradation products of CL-20 in two sandy soils under abiotic and biotic anaerobic conditions. Biotic degradation was prevalent in the slightly acidic VT soil, which contained a greater organic C content, while the slightly alkaline SAC soil favored hydrolysis. CL-20 degradation was accompanied by the formation of formate, glyoxal, nitrite, ammonium, and nitrous oxide. Biotic degradation of CL-20 occurred through the formation of its denitrohydrogenated derivative (m/z 393 Da) while hydrolysis occurred through the formation of a ring cleavage product (m/z 156 Da) that was tentatively identified as CH2 N\u2013C( N\u2013NO2)\u2013CH N\u2013CHO or its isomer N(NO2) CH\u2013CH N\u2013CO\u2013CH NH. Due to their chemical specificity, these two intermediates may be considered as markers of in situ attenuation of CL-20 in soil.NRC publication: Ye

Antigen-presenting cells transfected with Hsp65 messenger RNA fail to treat experimental tuberculosis

In the last several years, the use of dendritic cells has been studied as a therapeutic strategy against tumors. Dendritic cells can be pulsed with peptides or full-length protein, or they can be transfected with DNA or RNA. However, comparative studies suggest that transfecting dendritic cells with messenger RNA (mRNA) is superior to other antigen-loading techniques in generating immunocompetent dendritic cells. In the present study, we evaluated a new therapeutic strategy to fight tuberculosis using dendritic cells and macrophages transfected with Hsp65 mRNA. First, we demonstrated that antigen-presenting cells transfected with Hsp65 mRNA exhibit a higher level of expression of co-stimulatory molecules, suggesting that Hsp65 mRNA has immunostimulatory properties. We also demonstrated that spleen cells obtained from animals immunized with mock and Hsp65 mRNA-transfected dendritic cells were able to generate a mixed Th1/Th2 response with production not only of IFN-γ but also of IL-5 and IL-10. In contrast, cells recovered from mice immunized with Hsp65 mRNA-transfected macrophages were able to produce only IL-5. When mice were infected with Mycobacterium tuberculosis and treated with antigen-presenting cells transfected with Hsp65 mRNA (therapeutic immunization), we did not detect any decrease in the lung bacterial load or any preservation of the lung parenchyma, indicating the inability of transfected cells to confer curative effects against tuberculosis. In spite of the lack of therapeutic efficacy, this study reports for the first time the use of antigen-presenting cells transfected with mRNA in experimental tuberculosis

Microwave-assisted hydrolysis of nitroglycerine (NG) under mild alkaline conditons : New insight into the degradation pathway

Nitroglycerin (NG), a nitrate ester, is widely used in the pharmaceutical industry and as an explosive in dynamite and as propellant. Currently NG is considered as a key environmental contaminant due to the discharge of wastewater tainted with the chemical from the military and pharmaceutical industry. The present study describes hydrolytic degradation of NG (200 \u3bcM) at pH 9 using either conventional or microwave-assisted heating at 50 \ub0C. We found that hydrolytic degradation of NG inside the microwave chamber was much higher than its degradation using conventional heating. Products distributions in both heating systems were closely related and included nitrite, nitrate, formic acid, and the novel intermediates 2-hydroxypropanedial (O=CHCH(OH)HC=O) and glycolic acid (CH\u2082(OH)COOH). Two other intermediates glycolaldehyde (CH\u2082(OH)CHO) and glyoxylic acid (CHOCOOH) were only detected in the microwave treated samples. The molar ratio of nitrite to nitrate in the presence and absence of microwave heating was 2.5 and 2.8, respectively. In both microwave assisted and conventional heating a nitrogen mass balance of 96% and 98% and a carbon mass balance of 58% and 78%, respectively, were obtained. The lower C mass recovery might be attributed to further unknown reactions, e.g., polymerization of the aldehydes CH\u2082(OH)CHO, CHOCOOH and O=CHCH(OH)HC=O. A hydrolytic degradation pathway for NG was proposed involving denitration (loss of 2 NO-\u2082 ) from the two primary carbons and the loss of one nitrate from the secondary carbon to produce 2-hydroxypropanedial.Peer reviewed: YesNRC publication: Ye

Photolysis of RDX and nitroglycerin in the context of military training ranges.

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and nitroglycerin (NG) are two energetic materials commonly found in the environment on military training ranges. They are deposited on the ground in the form of solid particles, which can then dissolve in infiltration water or in surface water bodies. The objective of this study was to evaluate whether photolysis by sunlight can significantly contribute to the natural attenuation of RDX and NG (as solid particles or dissolved in surface water) at mid-northern latitudes, where training ranges of Canada and many European countries are located. Experiments conducted at 46.9 degrees N show that both compounds are degraded by sunlight when dissolved in water, with half-lives between 1 and 120d, depending on the compound and time of year. Numerical models may be useful in predicting such photolysis rates, but the models should take into account current ozone levels, as older radiation datasets, collected before the ozone depletion observed since the late 1970s, underestimate the RDX/NG photolysis rate. For solid RDX or NG-bearing particles, photolysis is slower (half-lives of 2-4months), but the degradation rate is still rapid enough to make this process significant in a natural attenuation context. However, photolysis of NG embedded within solid propellant particles cannot proceed to completion, due to the stable nitrocellulose matrix of the propellant. Nonetheless, photolysis clearly constitutes an important attenuation mechanism that should be considered in conceptual models and included in numerical modeling efforts

Transformation of 2,4-6-trinitrotoluene (TNT) by immobilized Phanerochaete chrysosporium under fed-batch and continuous TNT feeding conditions

NRC publication: Ye