Novel fluorine-containing energetic materials: how potential are they? A computational study of detonation performance.

CONTEXT: High-energy density materials (HEDMs) have emerged as a research focus due to their advantageous ultra-high detonation performance and better sensitivity. The primary aim of this study revolves around crafting HEDMs that strike a delicate balance between exceptional performance and minimal sensitivity. Density functional theory (DFT) was utilized to evaluate the geometric structures, energies, densities, energy properties, and sensitivities of 39 designed derivatives. The theoretical density (ρ) and heat of formation (HOF) were used to estimate the detonation velocity (D) and pressure (P) of the title compounds. Our study shows that the introduction of fluorine-containing substituents or fluorine-free substituents into the CHOFN backbone or the CHON backbone can significantly enhance the detonation performance of derivatives. Derivative B1 exhibits the better overall performance, including superior density, detonation performance, and sensitivity (P = 58.89 GPa, D = 8.02 km/s, ρ = 1.93 g/cm3, and characteristic height H50 = 34.6 cm). Our molecular design strategy contributes to the development of more novel HEDMs with excellent detonation performance and stability. It also marks a significant step towards a material engineering era guided by theory-based rational design. METHODS: GaussView 6.0 was used for construction of molecular system coordinates, and Gaussian 16 was used to obtain optimal structures, energies, and volumes of all compounds at the B3LYP/6-31+G(d,p) level of theory. It was characterized to be the local energy minimum on the potential energy surface without imaginary frequencies at the same theory level. Molecular weight, isosurface area, and overall variance were obtained using the Multiwfn 3.3. The detonation properties of the materials were analyzed using the C-J thermodynamic detonation theory. Our broad analysis facilitated an extensive assessment of these properties.

The role of Notch signaling pathway in metabolic bone diseases.

Metabolic bone diseases is the third most common endocrine diseases after diabetes and thyroid diseases. More than 500 million people worldwide suffer from metabolic bone diseases. The generation and development of bone metabolic diseases is a complex process regulated by multiple signaling pathways, among which the Notch signaling pathway is one of the most important pathways. The Notch signaling pathway regulates the differentiation and function of osteoblasts and osteoclasts, and affects the process of cartilage formation, bone formation and bone resorption. Genetic mutations in upstream and downstream of Notch signaling genes can lead to a series of metabolic bone diseases, such as Alagille syndrome, Adams-Oliver syndrome and spondylocostal dysostosis. In this review, we analyzed the mechanisms of Notch ligands, Notch receptors and signaling molecules in the process of signal transduction, and summarized the progress on the pathogenesis and clinical manifestations of bone metabolic diseases caused by Notch gene mutation. We hope to draw attention to the role of the Notch signaling pathway in metabolic bone diseases and provide new ideas and approaches for the diagnosis and treatment of metabolic bone diseases.

Synergistic Flame Retardancy of Phosphatized Sesbania Gum/Ammonium Polyphosphate on Polylactic Acid.

Phosphating sesbania gum (DESG) was obtained by modifying sesbania gum (SG) with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and endic anhydride (EA). The structure of DESG was determined using Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance spectroscopy (1H-NMR). Flame-retardant polylactic acid (PLA) composites were prepared by melt-blending PLA with DESG, which acted as a carbon source, and ammonium polyphosphate (APP), which acted as an acid source and a gas source. The flame retardancy of the PLA composite was investigated using vertical combustion (UL-94), the limiting oxygen index (LOI) and the cone calorimeter (CONE) test. Thermal properties and morphology were characterized via thermogravimetric analysis (TGA) and field emission scanning electron microscopy (FESEM), respectively. Experimental results indicated that when the mass ratio of DESG/APP was equal to 12/8 the LOI value was 32.2%; a vertical burning test (UL-94) V-0 rating was achieved. Meanwhile, the sample showed a lowest total heat release (THR) value of 52.7 MJ/m2, which is a 32.5% reduction compared to that of neat PLA. Using FESEM, the uniform distribution of DESG and APP in the PLA matrix was observed. The synergistic effect of DESG and APP effectively enhanced the flame retardancy of PLA. Additionally, the synergistic mechanism of DESG and APP in PLA was proposed.

Biochemical, molecular, and morphological variations of flight muscles before and after dispersal flight in a eusocial termite, Reticulitermes chinensis.

Swarming behavior facilitates pair formation, and therefore mating, in many eusocial termites. However, the physiological adjustments and morphological transformations of the flight muscles involved in flying and flightless insect forms are still unclear. Here, we found that the dispersal flight of the eusocial termite Reticulitermes chinensis Snyder led to a gradual decrease in adenosine triphosphate supply from oxidative phosphorylation, as well as a reduction in the activities of critical mitochondrial respiratory enzymes from preflight to dealation. Correspondingly, using three-dimensional reconstruction and transmission electron microscopy (TEM), the flight muscles were found to be gradually deteriorated during this process. In particular, two tergo-pleural muscles (IItpm5 and III-tpm5) necessary to adjust the rotation of wings for wing shedding behavior were present only in flying alates. These findings suggest that flight muscle systems vary in function and morphology to facilitate the swarming flight procedure, which sheds light on the important role of swarming in successful extension and fecundity of eusocial termites.

Synchronization of the Networked System With Continuous and Impulsive Hybrid Communications.

Many networked systems display some kind of dynamics behaving in a style with both continuous and impulsive communications. The cooperation behaviors of these networked systems with continuous connected or impulsive connected or both connected topologies of communications are important to understand. This paper is devoted to the synchronization of the networked system with continuous and impulsive hybrid communications, where each topology of communication mode is not connected in every moment. Two kind of structures, i.e., fixed structure and switching structures, are taken into consideration. A general concept of directed spanning tree (DST) is proposed to describe the connectivity of the networked system with hybrid communication modes. The suitable Lyapunov functions are constructed to analyze the synchronization stability. It is showed that for fixed topology having a jointly DST, the networked system with continuous and impulsive hybrid communication modes will achieve asymptotic synchronization if the feedback gain matrix and the average impulsive interval are properly selected. The results are then extended to the switching case where the graph has a frequently jointly DST. Some simple examples are then given to illustrate the derived synchronization criteria.