Theoretical study on the thermal dissociation of FOX-7 promoted by NO2

1,1-diamino-2,2-dinitroethene (FOX-7) is a novel energetic material with high performance and low sensitivity. In order to deeply understand the reaction mechanism in the initiation “hot spots” of FOX-7 and reveal the growth mechanism of these initiation “hot spots” in the explosion process, the detailed mechanisms of bimolecular reaction of NO2 and FOX-7, as well as the subsequent reactions have been investigated by the quantum chemical calculations. The mechanism of NO2 and FOX-7 bimolecular reaction and the catalytic effect of NO2 were revealed by three key dissociation paths. It is demonstrated that the NO2 molecule plays an important role in promoting the decomposition of the FOX-7 molecule, and the main exothermic pathways were the reactions between oxidizing intermediates (NO, NO2), and reducing intermediates (CO, NH3).

Thermodynamic modeling of melt of the Bi-Pb-Sn-Cd system

Thermodynamic modeling of heating of the Bi-Pb-Sn-Cd system in a wide temperature range is performed in the TERRA software package. The equilibrium constants of thermal dissociation reactions are determined. The equilibrium constants of thermal dissociation reactions for metal compounds formed in the Bi-Pb-Sn-Cd melt as a result of heating are determined: BiPb, PbSn, SnBi, Pb3Bi, Pb5Bi4Sn4, PbSn3, Bi2Sn3, Bi7Pb, CdSn, Sn3Bi, PbBi2Sn2, Pb3Bi4, Cd3Bi2, Bi7Pb3, Sn4Bi2.

Light-fueled transient supramolecular assemblies in water as fluorescence modulators

Dissipative self-assembly, which requires a continuous supply of fuel to maintain the assembled states far from equilibrium, is the foundation of biological systems. Among a variety of fuels, light, the original fuel of natural dissipative self-assembly, is fundamentally important but remains a challenge to introduce into artificial dissipative self-assemblies. Here, we report an artificial dissipative self-assembly system that is constructed from light-induced amphiphiles. Such dissipative supramolecular assembly is easily performed using protonated sulfonato-merocyanine and chitosan based molecular and macromolecular components in water. Light irradiation induces the assembly of supramolecular nanoparticles, which spontaneously disassemble in the dark due to thermal back relaxation of the molecular switch. Owing to the presence of light-induced amphiphiles and the thermal dissociation mechanism, the lifetimes of these transient supramolecular nanoparticles are highly sensitive to temperature and light power and range from several minutes to hours. By incorporating various fluorophores into transient supramolecular nanoparticles, the processes of aggregation-induced emission and aggregation-caused quenching, along with periodic variations in fluorescent color over time, have been demonstrated. Transient supramolecular assemblies, which act as fluorescence modulators, can also function in human hepatocellular cancer cells.

Thermodynamic Analysis of Siderite Ore Carbonate Decomposition Process at Roasting

Carbonate decomposition with significant heat energy absorption takes place at siderite ore oxidizing roasting in a shaft furnace. Thermal dissociation of complex carbonates comprising the siderite ore was studied. Thermodynamic analysis was carried out for a sideroplesite decomposition process. Formulas allowing determination of the carbonate dissociation and exchange energy rates were obtained using the regular ion solution theory. The ion composition and thermodynamic activity simulation results were described for sideroplesites as well as iron and magnesium cation shares. The work output is of certain interest as knowing the initial sideroplesite decomposition temperature and the carbonate dissociation rate the optimal dimensions of various zones throughout the shaft furnace height may be defined, the roasting process time may be calculated and the optimal heat treatment conditions as well as the firing rate may be established.

Impact of ozone and inlet design on the quantification of isoprene-derived organic nitrates by thermal dissociation cavity ring-down spectroscopy (TD-CRDS)

We present measurements of isoprene-derived organic nitrates (ISOP-NITs) generated in the reaction of isoprene with the nitrate radical (NO3) in a 1 m3 Teflon reaction chamber. Detection of ISOP-NITs is achieved via their thermal dissociation to nitrogen dioxide (NO2), which is monitored by cavity ring-down spectroscopy (TD-CRDS). Using thermal dissociation inlets (TDIs) made of quartz, the temperature-dependent dissociation profiles (thermograms) of ISOP-NITs measured in the presence of ozone (O3) are broad (350 to 700 K), which contrasts the narrower profiles previously observed for, for example, isopropyl nitrate (iPN) or peroxy acetyl nitrate (PAN) under the same conditions. The shape of the thermograms varied with the TDI's surface-to-volume ratio and with material of the inlet walls, providing clear evidence that ozone and quartz surfaces catalyse the dissociation of unsaturated organic nitrates leading to formation of NO2 at temperatures well below 475 K, impeding the separate detection of alkyl nitrates (ANs) and peroxy nitrates (PNs). The use of a TDI consisting of a non-reactive material suppresses the conversion of isoprene-derived ANs at 473 K, thus allowing selective detection of PNs. The potential for interference by the thermolysis of nitric acid (HNO3), nitrous acid (HONO) and O3 is assessed.

Study the Polymerization Kinetics of Polyaniline by UV-Vis and HPLC and Determination of the Thermodynamic Functions using Coats-Redfern Equation from TGA Curves

This study includes the preparation of the polyaniline at the laboratory temperature in an acidic medium. The Scanning Electron Microscopy (SEM) analysis of Polyaniline shows smooth surface and uniform nanoparticles formation with diameters of 56.4 to 90 nm. The polymerization of polyaniline kinetics was studied with two methods: UV-Vis, HPLC. Then the polymerization of polyaniline reaction order was determined and it was the zero-order reaction (n=0) in both of the previous two methods. The study of thermal dissociation indicates the temporal stability of chemicals, and study the decomposition kinetics to determine the thermodynamic functions of material disintegration. There are many methods use mathematical equations applied to TGA to study this phenomenon. The thermodynamic functions of the prepared polymers such as (G*, S*, H*) were determined based on Coats-Redfern equation from TGA curves of the compounds at each step of the disintegration.

Accurate Prediction of Total PlGF (Placental Growth Factor) From Free PlGF and sFlt-1 (Soluble Fms-Like Tyrosine Kinase-1): Evidence for Markedly Elevated PlGF Levels in Women With Acute Fatty Liver of Pregnancy

Acute fatty liver of pregnancy (AFLP) is characterized by elevated circulating sFlt-1 (soluble Fms-like tyrosine kinase-1), although the free circulating levels of its ligand, PlGF (placental growth factor) are not decreased. Here, we hypothesized that women with AFLP exhibit elevated PlGF production in comparison to women with preeclampsia or hemolysis elevated liver enzymes and low platelet count syndrome. Making use of the well-known mathematical formulas describing drug-receptor interactions, we established that serum total PlGF could be accurately predicted from sFlt-1 and free PlGF levels (n=42; mean calculated K D of 50 pmol/L), yielding similar values as the previously published method of thermal dissociation of the sFlt-1-PlGF complexes ( r =0.94, P <0.0001). We found that median levels of free PlGF were significantly lower in women with preeclampsia (n=13; 117pg/mL) or hemolysis elevated liver enzymes and low platelet count syndrome (n=12; 59 pg/mL) compared with women without preeclampsia (n=11; 349pg/mL, P <0.0001). In contrast, median total PlGF did not differ between women with no preeclampsia, preeclampsia, and hemolysis elevated liver enzymes and low platelet count syndrome (354 versus 435 versus 344pg/mL), whereas it was markedly elevated in AFLP compared with all groups (2054 pg/mL, P <0.0001). Furthermore, in AFLP, both sFlt-1 and total PlGF declined rapidly postdelivery, with significantly higher predelivery total PlGF (n=12; median, 2054 pg/mL) than postpartum levels (n=14; median,163pg/mL, P <0.0001), suggesting that in AFLP, PlGF is largely placenta-derived. Collectively, our findings indicate that like sFlt-1, PlGF production is significantly upregulated in AFLP, mainly originating from the placenta. Importantly, total PlGF can now be easily calculated from already available free PlGF and sFlt-1 levels, allowing subsequent evaluation of other groups in whom PlGF is altered.

Thermal dissociation cavity-enhanced absorption spectrometer for measuring NO₂, RO₂NO₂, and RONO₂ in the atmosphere

We developed thermal dissociation cavity-enhanced absorption spectroscopy (TD-CEAS) for the in situ measurement of NO2, total peroxy nitrates (PNs, RO2NO2), and total alkyl nitrates (ANs, RONO2) in the atmosphere. PNs and ANs were thermally converted to NO2 at the corresponding pyrolytic temperatures and detected by CEAS at 435–455 nm. The instrument sampled sequentially from three channels at ambient temperature, 453 and 653 K, with a cycle of 3 min, to measure NO2, NO2+ PNs, and NO2+ PNs + ANs. The absorptions between the three channels were used to derive the mixing ratios of PNs and ANs by spectral fitting. The detection limit (LOD, 1σ) for retrieving NO2 was 97 parts per trillion by volume (pptv) in 6 s. The measurement uncertainty of NO2 was 9 %, while the uncertainties of PN and AN detection were larger than those of NO2 due to chemical interferences that occurred in the heated channels, such as the reaction of NO (or NO2) with the peroxy radicals produced by the thermal dissociation of organic nitrates. Based on laboratory experiments and numerical simulations, we created a lookup table method to correct these interferences in PN and AN channels under various ambient organic nitrates, NO, and NO2. Finally, we present the first field deployment and compare it with other instruments during a field campaign in China. The advantages and limitations of this instrument are outlined.