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Query: UMLS:C0267964 (
PAA
)
2,561
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Hexahydro-1,3,5-trinitro-
1,3,5-triazine
(RDX) is a common contaminant of soil and water at military facilities. The present study describes degradation of RDX with zerovalent iron nanoparticles (ZVINs) in water in the presence or absence of a stabilizer additive such as carboxymethyl cellulose (CMC) or poly(acrylic acid) (
PAA
). The rates of RDX degradation in solution followed this order CMC-ZVINs >
PAA
-ZVINs > ZVINs with k1 values of 0.816 +/- 0.067, 0.082 +/- 0.002, and 0.019 +/- 0.002 min(-1), respectively. The disappearance of RDX was accompanied by the formation of formaldehyde, nitrogen, nitrite, ammonium, nitrous oxide, and hydrazine by the intermediary formation of methylenedinitramine (MEDINA), MNX (hexahydro-1-nitroso-3,5-dinitro-
1,3,5-triazine
), DNX (hexahydro-1,3-dinitroso-5-nitro-
1,3,5-triazine
), TNX (hexahydro-1,3,5-trinitroso-
1,3,5-triazine
). When either of the reduced RDX products (MNX or TNX) was treated with ZVINs we observed nitrite (from MNX only), NO (from TNX only), N2O, NH4+, NH2NH2 and HCHO. In the case of TNX we observed a new key product that we tentatively identified as 1,3-dinitroso-5-hydro-1,3,5-triazacyclo-hexane. However, we were unable to detect the equivalent denitrohydrogenated product of RDX and MNX degradation. Finally, during MNX degradation we detected a new intermediate identified as N-nitroso-methylenenitramine (ONNHCH2NHNO2), the equivalentof methylenedinitramine formed upon denitration of RDX. Experimental evidence gathered thus far suggested that ZVINs degraded RDX and MNX via initial denitration and sequential reduction to the corresponding nitroso derivatives prior to completed decomposition but degraded TNX exclusively via initial cleavage of the N-NO bond(s).
...
PMID:Degradation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) using zerovalent iron nanoparticles. 1860 56
A hydrogen bonded and calcium ion crosslinked hydrogel, termed PVDT-
PAA
, was synthesized by one-step photo-polymerization of 2-vinyl-4,6-diamino-
1,3,5-triazine
(VDT), acrylic acid (AA), and polyethylene glycol diacrylate (PEGDA, M
n
= 4000). Combined physical crosslinking from inter-diaminotriazine and coordination of Ca
2+
with carboxyls contributed to a significant enhancement in the mechanical properties of the PVDT-
PAA
hydrogels. Furthermore, reversible Ca
2+
crosslinking imparted shape memory properties to the hydrogel allowing it to firmly memorize multiform shapes and return to its initial state in response to Ca
2+
. Interestingly, PVDT-
PAA
hydrogels with weaker H-bonding interactions demonstrated a sharp volume change phenomenon induced by Ca
2+
. This volume change could be utilized to trigger unharmful cell detachment from the hydrogel surface, which was thought to be due to Ca
2+
-induced marked variation in mechanotransduction between the cells and the substrate interface. This H-bonding and ionic crosslinking strategy opens up a new opportunity for designing and constructing multifunctional high strength hydrogels for biomedical applications.
...
PMID:Hydrogen bonded and ionically crosslinked high strength hydrogels exhibiting Ca
2+
-triggered shape memory properties and volume shrinkage for cell detachment. 3226 53
