Decorated Oxidation-resistive deficient Titanium oxide nanotube supported NiFe-nanosheets as high-efficiency electrocatalysts for overall water splitting.

In this study, oxidation-resistive deficient TiO2-x supported NiFe-based electrocatalysts were developed towards efficient and durable water splitting performance. The oxidation-resistive deficient TiO2-x support with oxygen vacancies ensures good stability and electrical conductivity of the catalyst. The decorated NiFe and NiFeP nanosheets serve as efficient catalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. In 1 M KOH, the NiFe@TiO2-x and NiFeP@TiO2-x electrodes show low overpotential for OER (300 mV) and HER (273 mV) at 100 mA cm-2, respectively, and excellent stability performance in overall water splitting as well. In-situ Raman and theoretical analysis reveals that the in-situ formed Fe3+-doped NiOOH species are essential in catalyzing OER on NiFe@TiO2-x, particularly the electron localization of surface Fe-O bonds offers lower energy barriers for OER elemental reactions and thus enhance its catalytic activity. This work provides an oxide-based catalyst support strategy for the development of stable and active overall water splitting catalysts, and advances the insights on catalytic origin of NiFe-based catalysts as well.

Polycyclic aromatic hydrocarbon occurrence in forest soils in response to fires: a summary across sites.

Forest fires are important sources of polycyclic aromatic hydrocarbons (PAHs) in soils. However, factors controlling PAH production in soils subjected to fires in different sites are poorly understood. Here, we analyzed 143 sets of previously published data to evaluate the concentrations and composition profiles of PAHs in ash and soils associated with forest fires and to assess the impacts of soil depth, fire intensity, post-fire duration, and vegetation type on their occurrence. Compared to unburned soils, the total PAH concentrations increased by 205% (95% confidential interval of 152-269%; n = 136) in soils associated with fires. This increase surpassed that of PAH toxic equivalents (73%) because fires produce dominantly low-ring PAHs with relatively low toxicity. PAH concentrations in fire-impacted sites increased by 684%, 258%, and 155% in the ash, 0-5 cm soil depth interval, and >5 cm soil depth interval, respectively. The increases in PAH concentrations associated with mild-intensity fires (412%) exceeded those associated with moderate-intensity (163%) and high-intensity (168%) fires, which is possibly due to pyromineralization or volatilization of organic matters at high burning temperatures. These increases were highest within a month after the fire (280%), gradually decreasing over time, and showed no significant difference compared to the reference sites after 24 months. The concentration increases exhibit no major difference between various vegetation types (broad-leaved forest vs. coniferous forest vs. shrub). Assessments reveal that exposure to post-fire soil PAHs involves no serious human health risk. However, potential adverse effects of soil PAHs on other organisms (e.g., microbes and plants) and ecosystems should be further examined. The present study highlights the strong impacts of soil depth, fire intensity, and post-fire duration, and the relatively weak impact of the vegetation type on PAH concentrations in soils associated with fires in different areas.

Experimental study on microstructure and mechanical properties of stalk for Glycyrrhiza Glabra.

In this paper, a year-old stalk of Glycyrrhiza glabra was used as the research object. The electronic universal testing machine was used to test the mechanical properties of shearing and bending. The microstructure of the stalk of Glycyrrhiza glabra was observed with a microscope. Mechanical test research indicated that the shearing process included an elastic phase, a yield phase, and a plastic deformation phase. The bending process was divided into elastic deformation stage and plastic deformation stage. In addition, the shearing force, shearing energy, bending force and bending energy all increased with the increase in diameter. As the water content increased, the shearing force and bending force decreased at first, reached the minimum when the water content was about 45%, and then had an upward trend. The shearing energy increased with the water content, and the bending energy, decreased with the water content. The two test factors were statistically significant for both shearing and bending properties. The microscopic test results showed that the phloem, fiber, and pith constitute the microstructure of the licorice stalk. The linear regression model could reflect the correlation between the cross-sectional area of each part and the shearing force and bending force (P < 0.05). Through analysis, it was concluded that the change of the cross-sectional area of the stalk microstructure had an important influence on the mechanical properties of shearing and bending. The results can provide theoretical basis for the design of Glycyrrhiza Glabra stalk harvesting, crushing and processing equipment.

A One-Step Approach to N-(Hetero)aryl-3,5-dinitropyrazoles from (Hetero)aryl Amines.

Potassium 1,1,3,3-tetranitropropane-1,3-diide (K2TNP) was found to react readily with various (hetero)aryl amines (12 examples) to give corresponding N-(hetero)aryl-3,5-dinitropyrazoles in moderate to excellent yields. The reactions were performed at mild temperature, and most of the reactions completed in less than 4 h. Four potential energetic compounds show high enthalpy of formation, excellent thermal stability, and good sensitivity, with 3-(3,5-dinitropyrazol-1-yl)-1H-1,2,4-triazole (3j) being a potential 2,2',4,4',6,6'-hexanitrostibene (HNS) replacement.

Potassium Nitraminofurazan Derivatives: Potential Green Primary Explosives with High Energy and Comparable Low Friction Sensitivities.

Lead-based primary explosives were widely applied in military and civilian ammunition, which have subsequently caused serious environmental and health-related problems. Therefore, the development of green alternatives for the lead-based primary explosives has been one of the major focuses in the field of energetic materials. Four potassium salts based on nitraminofurazan have been easily synthesized and show excellent comprehensive performances. Among them, potassium 3-dinitromethyl-4-nitraminofurazan (K2 DNMNAF, 1) showed better thermal stability (Td : 281.4 °C), higher density (2.174 g cm-3 ), and lower friction sensitivities (72 N) than that of potassium 4,5-bis(dinitromethyl)furoxanate (K2 BDNMF, Td : 218.3 °C, density: 2.130 g cm-3 , FS: 5 N, P: 27.3 GPa, vD : 7759 m s-1 ); furthermore, it displayed comparable detonation performances (P: 27.2 GPa, vD : 7758 m s-1 ). The promising properties of these salts make this kind of material a competitive alternative to lead azide as a primary explosive.

1,2,4,5-Dioxadiazine-functionalized [N-NO2]- furazan energetic salts.

The 1,2,4,5-dioxadiazine ring was introduced as a bridge connecting two nitraminofurazan moieties to form energetic salts based on 3,6-bis(4-nitramino-1,2,5-oxadiazol-3-yl)-1,2,4,5-dioxadiazine (H2BNOD). Eight nitrogen-rich energetic salts based on the BNOD anion were synthesized and fully characterized by NMR (1H NMR, 13C NMR, 15N NMR), IR and elemental analysis. Furthermore, H2BNOF (5), ammonium (6), hydroxylammonium (8) and 4-amino-1,2,4-triazolium salts (13) were analyzed by single-crystal X-ray diffraction. The densities of the salts were in the range of 1.730 (13) to 1.914 g cm-3 (8). These salts showed much better thermal stabilities and mechanical sensitivities than their precursor, H2BNOD. The decomposition temperatures of the salts ranged from 114 (6) to 197 °C (9). The impact sensitivities of the energetic salts were between 1.5 and 4.5 J, and their friction sensitivities ranged from 53 to >144 N. Their detonation pressures and detonation velocities were calculated to be in the range of 26.3 (12) to 38.1 GPa (8), and 7754 (12) to 9095 m s-1 (8), respectively.

High-Oxygen-Balance Furazan Anions: A Good Choice for High-Performance Energetic Salts.

3,4-Diaminofurazan was conveniently converted into energetic salts of 3,4-dinitraminofurazan that were paired with nitrogen-rich cations in fewer than three steps. Seven energetic salts were prepared and fully characterized by multinuclear ((1) H, (13) C) NMR and IR spectroscopy, differential scanning calorimetry (DSC), and elemental analysis. In addition, the structures of the ammonium salt (2), hydrazinium salt (4), hydroxylammonium salt (5), aminoguanidinium salt (7), diaminoguanidinium salt (8) and triaminoguanidinium salt of 3,4-dinitraminofurazan (9) were further confirmed by single-crystal X-ray diffraction. The densities of these salts were between 1.673 (8) and 1.791 g cm(-3) (5), whilst their oxygen balances were between -48.20 % (9) and -6.25 % (5). These salts showed high thermal stabilities, with decomposition temperatures between 179 (5) and 283 °C (6). Their sensitivities towards impact and friction were measured by BAM equipment to be between <1 J (9) and >40 J (6-8) and 64 N (9) and >360 N (6), respectively. The detonation performance of these compounds, which was calculated by using the EXPLO5 program, revealed detonation pressures of between 28.0 (6) and 40.5 GPa (5) and detonation velocities of between 8404 (6) and 9407 m s(-1) (5).