Effect of Nanomaterials on Thermal Stability of 1,3,6,8-Tetranitro Carbazole

1,3,6,8-tetranitro carbazole (TNC) as a secondary explosive is used in composite explosive formulations in order to reduce the sensitivity and increase the stability of the explosive composites. In this work, the thermal stabilities of pure TNC and its nanocomposites prepared via three different nanoparticles were studied by thermal analysis, i.e. differential scanning calorimetery (DSC) and thermogravimetry (TG) techniques. Thermal analysis data revealed that the thermal behavior of pure TNC is significantly different from the nanocomposites studied. Pure TNC decomposed completely during a single step in the temperature range 385-425 °C. However, the addition of nanoparticles to the TNC powder leads to higher thermal stability in comparison with the pure TNC. The decomposition kinetics of TNC and its nanocomposites were studied by non-isothermal DSC at several heating rates. Thermokinetic and thermodynamic parameters corresponding to the thermal decomposition of pure TNC and nanocomposites were computed and compared. The results showed that the addition of nanoparticles to the TNC powder has a considerable effect on the thermal stability of the explosive

Extended structures in copper(II) complexes with 4-hydroxypyridine-2,6-dicarboxylate and pyrimidine derivative ligands: X-ray crystal structure, solution and magnetic studies

Three new copper(II) complexes of chelidamic acid (H(3)cda) and pyrimidine derivatives, namely [Cu-2 (Hcda)(2)(ampym)(2)]center dot 5H(2)O (1) and [Cu-2(Hcda)(2)(apym)(H2O)(2)]center dot 2H(2)O (2), and (Hapym)(2)[Cu(Hcda)(2)]center dot 4H(2)O (3) (ampym = 2-amino-4-methylpyrimidine, apym = 2-aminopyrimidine) have been synthesised in mild conditions starting from the proton transfer compounds (Hampym)(2)(Hcda) and (Hapym)(2)(Hcda). X-ray diffraction analysis revealed the formation of extended structures featuring dinuclear (1 and 2 with pyrimidine derivatives as metal bridges) or mononuclear (3) Hcda(2) copper(II) complex units joined via H-bonds mainly involving coordinated and lattice water molecules and the coordinated Hcda(2) ligands. Solution studies, magnetic measurements and thermal analyses were performed to fully characterise the new compounds

In vitro antibacterial property assessment of silver nanoparticles synthesized by Falcaria vulgaris aqueous extract against MDR bacteria

Silver nanoparticles (AgNPs) were fabricated in the presence of Falcaria vulgaris aqueous extract as a biosynthesis method without utilizing any surfactant or template. AgNPs were prepared under different synthesis conditions such as silver ion concentration and the amount of plant used for the extraction, reaction duration and temperature for the extraction. The effect of these variables on the size of resulted AgNPs was examined, and operation conditions were optimized statistically with analysis of variance (ANOVA) to describe the role of these variables in tuning the size of AgNPs. The results of ANOVA displayed the optimum conditions for the synthesis procedure that resulted in AgNPs with the average size of 28 ± 8 nm. Furthermore, the growth of AgNPs was monitored by UV-Vis spectroscopy, and they were characterized using TEM, SEM, X-ray diffraction, and FT-IR spectroscopy. Finally, in vitro antibacterial activity of the AgNPs showed the maximum inhibition zone alongside Staphylococcus aureus (ATCC 25923) and lowermost inhibition zone touching E. coli (MDR). The minimum inhibitory concentration (MIC) for the AgNP-Fv was in a range between 0.535 and 0.001 µg/ml. According to the results, the ATCC bacteria were more sensitive to AgNP-Fv compared to multiple-drug resistance bacteria, except for Pseudomonas aeruginosa (MDR). Figure not available: see fulltext.. © 2019, Springer Science+Business Media, LLC, part of Springer Nature

Electrochemical synthesis of copper carbonates nanoparticles through experimental design and the subsequent thermal decomposition to copper oxide

A copper anode was used in sodium carbonate solutions to prepare nanoparticles of copper carbonates. To reach the best results, the parameters affecting the preparation procedure were evaluated and optimized based on the Taguchi robust design (TRD), and it was found that the size of the resulting copper carbonates particles could be managed by applying optimal values of parameters such as electrolysis voltage, carbonate concentration, stirring rate and the temperature. To evaluate how significantly the factors influence the size of the particles, analysis of variance (ANOVA) was used, and the results indicated that the electrolysis voltage, carbonates concentration, and stirring rate affect the dimensions of the particles to a high degree. The optimal conditions were also evaluated. Further, the copper carbonate particles were used as the precursor in a solid-state thermal decomposition reaction intended for forming nanostructured CuO particles. All products were studied through SEM, XRD, TG-DTA, and FT-IR techniques and also those of optimal properties were evaluated as photocatalytic species for application in the UV-induced degradation (UVID) of methylene blue (MB). © 2019 IOP Publishing Ltd