Herein, we report a new strategy for developing an on-off-on molecular "light switch" by utilizing the pH value to control the "conformational switch" of G-quadruplex DNA. A novel ruthenium(II) complex with an emission enhancement factor of 150 was synthesized and introduced to detect the switch by the naked eye. The "light switch" can be repeatedly cycled off and on through the addition of H(+) and OH(-), respectively. The conformational transitions of G-quadruplex DNA in K(+) solution at different pH values in the acidic region were evidenced by circular dichroism and fluorescence titrations. Computational calculations by applying density functional theory (DFT)/time-dependent DFT and molecular docking were also carried out to gain insight into the "light-switch" mechanism.

A new green primary explosive, dipotassium 3,4-bis(3-dinitromethylfurazan-4-oxy)furazan (K 2 BDFOF), was synthesized via a four-step procedure including cyano addition, diazotization, N 2 O 5 nitration, and KI reduction. The compound was characterized by multinuclear NMR spectroscopy, IR spectroscopy, elemental analysis, DSC, TG/DTG as well as single crystal X-ray diffraction. X-ray diffraction studies reveal 10 an intriguing 3D framework structure. The central K ions are linked by dinitromethanide anions to give a 1D spiral chain with parallelogram-like repeat units, and these 1D chains are further linked by one oxygen atom in the nitro group coordinated with K ion to form a two-dimensional wave-like layer structure. Additionally the kinetic parameters of the exothermic process for K 2 BDFOF were studied by Kissinger's and Ozawa-Doyle's methods. The sensitivities were determined by standardised impact and 15 friction tests, and the heat of formation was calculated with the atomization method at the CBS-4M level of theory. With the heat of formation (-8.4 kJ mol −1 ) and the room-temperature X-ray density (2.09 g cm −3 ), impressive values for the detonation parameters such as detonation velocity (8431 m s −1 ) and pressure (329 kbar) were computed using the EXPLO5 program and compared to the most commonly used primary explosive lead azide as well as recently published dipotassium 1,1'-dinitramino-5,5'-20 bistetrazolate.

The cocrystallization of high-energy explosives has attracted great interests since it can alleviate to a certain extent the power-safety contradiction. 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaaza-isowurtzitane (CL-20), one of the most powerful explosives, has attracted much attention for researchers worldwide. However, the disadvantage of CL-20 has increased sensitivity to mechanical stimuli and cocrystallization of CL-20 with other compounds may provide a way to decrease its sensitivity. The intermolecular interaction of five types of CL-20-based cocrystal (CL-20/TNT, CL-20/HMX, CL-20/FOX-7, CL-20/TKX-50 and CL-20/DNB) by using molecular dynamic simulation was reviewed. The preparation methods and thermal decomposition properties of CL-20-based cocrystal are emphatically analyzed. Special emphasis is focused on the improved mechanical performances of CL-20-based cocrystal, which are compared with those of CL-20. The existing problems and challenges for the future work on CL-20-based cocrystal are discussed.

Several industrial- and research-type composite solid propellants containing different nano metric metal oxide catalysts (Fe2O3, Co3O4, CuO, and PbO) with similar nominal composition, were prepared and experimentally analyzed. The effects of different nano-sized metal oxide catalysts on the rheological properties and hazardous properties were investigated. The strand burning rate and the associated combustion flame structure of composite propellants were determined. The results show that the nano-sized metal oxide powders can be sufficiently dispersed in hydroxyl terminated polybutadiene binder. The propellant formulations containing nano metal oxide particles are sensitive to impact and friction except for the base propellant without nano-sized powders, which is less sensitive to friction as compared to the other compositions. The nano-sized metal oxide additives can affect the combustion behavior and increase the burning rate of propellants compared with the reference propellant composition

Polyvinylpyrrolidone (PVP) nanofilms prepared by spin-coating have vast applications in biological and microdevice fields. However, detailed knowledge of processing induced nonequilibrium behavior of PVP nanofilms and solutions for minimizing residual stresses toward high-quality films has still been lacking. In the present study, we first explored the rapid film formation process via statistics on nascent holes. Next, by employing dewetting as a major probe, we revealed that many processing conditions, particularly previously overlooked variables like the atmosphere, substrates, and immersion time, were correlated substantially with the degree of nonequilibrium of nanofilms. Proper aging temperature and time were demonstrated essential for releasing residual stresses and achieving more equilibrium nanofilms. This work offered abundant experimental evidence in the building relationship between the processing and nonequilibrium nature of polymer nanofilms, which were crucial for their preparation and application.

The thermal behavior of 1,1-diamino-2,2-dinitroethlene (DADNE) was followed by differential scanning calorimetry (DSC) and thermogravimetry (TG). In addition, it was further investigated by the combination techniques of in situ thermolysis cell or fast thermolysis probe with rapid-scan Fourier transform infrared spectroscopy (thermolysis/RSFT-IR and fast thermolysis/RSFT-IR) and by mass spectroscopy (MS). The results showed that there was a phase transition (beta-DADNE to gamma-DADNE) at the temperature of 119 degrees C, and that the gas products of DADNE consisted of CO2, CO, NO2, NO, N2O, HCN, and HNCO, of which CO2, NO, N2O, and HCN present themselves in both the first and second stages of DADNE decomposition process, whereas CO, NO2, and HNCO are only caused by the second stage, in air atmosphere. The C=C and C-NH2 bonds of DADNE molecules are broken in the first stage of the decomposition process in open air, and one of the C-NO2 and one of the C-NH2 bonds of the molecules are broken in the same stage under electrospray ionization condition.

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The microstructures and granularity distribution of different metal particles were investigated and the energy, sensitivity, and combustion properties of fuel rich solid propellants with different metal particles were studied in detail. It was found that the magnesium particles are more uniform than other metal powders, the mean diameter of the magnesium particles d50=67.6 μm is much higher than those of the other ones, which are in the range of 7.1 μm<d50<20.5 μm. Additionally, the preparation process of the Mg‐based propellant is easier than those of the other ones. The experimental results showed that the propellant containing magnesium powder was less sensitive to friction and impact (165.1 NM and 21.9 NM, respectively), whereas, the burning rates of propellants with Zr and ZrH2 particles increased, and the pressure exponents decreased.