A Facile and Versatile Synthesis of Energetic Furazan-Functionalized 5-Nitroimino-1,2,4-Triazoles

An analogue-oriented synthetic route for the formulation of furazan-functionalized 5-nitroimino-1,2,4-triazoles has been explored. The process was found to be straightforward, high yielding, and highly efficient, and scalable. Nine compounds were synthesized and the physicochemical and energetic properties, including density, thermal stability, and sensitivity, were investigated, as well as the energetic performance (e.g., detonation velocities and detonation pressures) as evaluated by using EXPLO5 code. Among the new materials, compounds 4 – 6 and 11 possess high densities, acceptable sensitivities, and good detonation performances, and thereby demonstrate the potential applications as new secondary explosives.     

Sustainable and Robust Graphene Cellulose Paper Decorated with Lithiophilic Au Nanoparticles to Enable Dendrite-free and High-Power Lithium Metal Anode

Lithium metal anodes (LMAs) with high energy density have recently captured increasing attention for development of next-generation batteries. However, practical viability of LMAs is hindered by the uncontrolled Li dendrite growth and infinite dimension change. Even though constructing 3D conductive skeleton has been regarded as a reliable strategy to prepare stable and low volume stress LMAs, engineering the renewable and lithiophilic conductive scaffold is still a challenge. Herein, a robust conductive scaffold derived from renewable cellulose paper, which is coated with reduced graphene oxide and decorated with lithiophilic Au nanoparticles, is engineered for LMAs. The graphene cellulose fibres with high surface area can reduce the local current density, while the well-dispersed Au nanoparticles can serve as lithiophilic nanoseeds to lower the nucleation overpotential of Li plating. The coupled relationship can guarantee uniform Li nucleation and unique spherical Li growth into 3D carbon matrix. Moreover, the natural cellulose paper possesses outstanding mechanical strength to tolerate the volume stress. In virtue of the modulated deposition behaviour and near-zero volume change, the hybrid LMAs can achieve reversible Li plating/stripping even at an ultrahigh current density of 10 mA cm⁻² as evidenced by high Coulombic efficiency (97.2 % after 60 cycles) and ultralong lifespan (1000 cycles) together with ultralow overpotential (25 mV). Therefore, this strategy sheds light on a scalable approach to multiscale design versatile Li host, promising highly stable Li metal batteries to be feasible and practical.     

互联网自治的改造实现

本文的自治互联网技术结合互联网现实,通过现有域名体系构造出自主自治的可扩展域名体系和层次结构,并提供自治网络系统内/间的域名解释机制,甚至可以单边行动的方式实现互联网自治的过渡和改造。     

Investigating the Photostability of Quantum Dots at the Single‐Molecule Level

Quantum dots (QDs) have shown great potential to provide spatial, temporal, and structural information for biological systems. However, blinking, photobleaching, and spectral blueshift are adverse effects on their practical applications in biomedical research. An investigation of the effects of six reducing agents including cysteine (Cys), 1,4‐dithiothreitol (DTT), ethyl gallate (EG), L ‐glutathione (GSH), mercaptoacetic acid (MAA), and thiourea (TU) on the photostability of single QDs was studied. Our experiments demonstrate that both DTT and EG effectively inhibit blinking, photobleaching, and spectral blueshift. GSH molecules block blinking and photobleaching of QDs. The other reagents, Cys, MAA, and TU, only have the ability to counteract blinking. Possible explanations are given on the basis of research evidence. The results suggest possibilities for significant improvements in QDs for biological applications by adjusting the environmental conditions.     

On the Hamming distances of repeated-root constacyclic codes of length 4ps

Let $p$ be an odd prime, $s$, $m$ be positive integers, $\gamma ,\lambda$ be nonzero elements of the finite field ${\mathbb{F}}_{p^m}$ such that ${\gamma }^{p^s}=\lambda$. In this paper, we show that, for any positive integer $\eta$, the Hamming distances of all repeated-root $\lambda$-constacyclic codes of length $\eta p^s$ can be determined by those of certain simple-root $\gamma$-constacyclic codes of length $\eta$. Using this result, Hamming distances of all constacyclic codes of length $4p^s$ are obtained. As an application, we identify all MDS $\lambda$-constacyclic codes of length $4p^s$.     

Synthesis,structural characterization and catalytic activity of benzimidazole‐functionalized Pd(II) N‐heterocyclic carbene complexes

Two Pd(II)–NHC complexes bearing benzimidazole and pyridine groups have been successfully prepared and fully characterized by NMR and X‐ray diffraction analysis. The structure of palladium complexes are a typical square‐planar with palladium surrounded by two pairs of trans‐arranged benzimidazole and carbene ligands. The Pd–NHC complexes have been proved to be a highly efficient catalyst for the Mizoroki–Heck coupling reaction of aryl halides with various substituted acrylates under mild conditions in excellent yields. Copyright © 2013 John Wiley & Sons, Ltd.     

Issue Information

Three‐dimensional direct numerical simulation results of flow past a circular cylinder are influenced by numerical aspects, for example the spanwise domain length and the lateral boundary condition adopted for the simulation. It is found that inappropriate numerical set‐up, which restricts the development of intrinsic wake structure, leads to an over‐prediction of the onset point of the secondary wake instability (Re_cr). A best practice of the numerical set‐up is presented for the accurate prediction of Re_cr by direct numerical simulation while minimizing the computational cost. The cylinder span length should be chosen on the basis of the intrinsic wavelength of the wake structure to be simulated, whereas a long span length is not necessary. For the wake transitions above Re_cr, because the wake structures no longer follow particular wavelengths but become disordered and chaotic, a span length of more than 10 cylinder diameters (approximately three times the intrinsic wavelength) is recommended for the simulations to obtain wake structures and hydrodynamic forces that are not strongly restricted by the numerical set‐up. The performances of the periodic and symmetry lateral boundary conditions are compared and discussed. The symmetry boundary condition is recommended for predicting Re_cr, while the periodic boundary condition is recommended for simulating the wake structures above Re_cr. The general conclusions drawn through a circular cylinder are expected to be applicable to other bluff body configurations. Copyright © 2017 John Wiley & Sons, Ltd.