After the discovery of fullerene-C60, it took almost two decades for the possibility of boron-based fullerene structures to be considered. So far, there has been no experimental evidence for these nanostructures, in spite of the progress made in theoretical investigations of their structure and bonding. Here we report the observation, by photoelectron spectroscopy, of an all-boron fullerene-like cage cluster at B40(-) with an extremely low electron-binding energy. Theoretical calculations show that this arises from a cage structure with a large energy gap, but that a quasi-planar isomer of B40(-) with two adjacent hexagonal holes is slightly more stable than the fullerene structure. In contrast, for neutral B40 the fullerene-like cage is calculated to be the most stable structure. The surface of the all-boron fullerene, bonded uniformly via delocalized σ and π bonds, is not perfectly smooth and exhibits unusual heptagonal faces, in contrast to C60 fullerene.

Sodium layered transition metal oxides have been considered as promising cathode materials for sodium ion batteries due to their large capacity and high operating voltage. However, mechanism investigations of chemical evolution and capacity failure at high voltage are inadequate. As a representative cathode, Na 2/3 Ni 1/3 Mn 2/3 O 2 , the capacity contribution at a 4.2 V plateau has long been assigned to the redox of the Ni 3+ /Ni 4+ couple, while at the same time it suffers large irreversible capacity loss during the initial discharging process. In this work, we prove that the capacity at the 4.2 V plateau is contributed to the irreversible O 2− /O 2 n− /O 2 evolution based on in situ differential electrochemical mass spectrometry and density functional theory calculation results. Besides, a phenomenon of oxygen release and subsequent surface lattice densification is observed, which is responsible for the large irreversible capacity loss during the initial cycle. Furthermore, the oxygen release is successfully suppressed by Fe substitution due to the formation of a unique Fe-(O−O) species, which effectively stabilizes the reversibility of the O 2− /O 2 n− redox at high operating voltage. Our findings provide a new understanding of the chemical evolution in layered transition metal oxides at high operating voltage. Increasing the covalency of the TM−O bond has been proven to be effective in suppressing the oxygen release and hence improving the electrochemical performance.

SUMMARYThis paper presents a novel computational approach, the discrete singular convolution (DSC) algorithm, for analysing plate structures. The basic philosophy behind the DSC algorithm for the approximation of functions and their derivatives is studied. Approximations to the delta distribution are constructed as either bandlimited reproducing kernels or approximate reproducing kernels. Uniÿed features of the DSC algorithm for solving di erential equations are explored. It is demonstrated that di erent methods of implementation for the present algorithm, such as global, local, Galerkin, collocation, and ÿnite di erence, can be deduced from a single starting point. The use of the algorithm for the vibration analysis of plates with internal supports is discussed. Detailed formulation is given to the treatment of di erent plate boundary conditions, including simply supported, elastically supported and clamped edges. This work paves the way for applying the DSC approach in the following paper to plates with complex support conditions, which have not been fully addressed in the literature yet.

Abstract-This letter introduces generalizations of the Perona-Malik equation. An edge enhancing functional is proposed for direct edge enhancement. A number of super diffusion operators is introduced for fast and effective smoothing. Statistical information is utilized for robust edge-stopping. Numerical integration is conducted by using a recently developed quasiinterpolating wavelet method. Computer experiments indicate that the present algorithm is very efficient for edge-detecting and noise-removing.

Fe­(VI) has received increasing attention since it can decompose a wide range of trace organic contaminants (TrOCs) in water treatment. However, the role of short-lived Fe­(IV) and Fe­(V) in TrOC decomposition by Fe­(VI) has been overlooked. Using methyl phenyl sulfoxide (PMSO), carbamazepine, and caffeine as probe TrOCs, we observed that the apparent second-order rate constants (k app) between TrOCs and Fe­(VI) determined with the initial kinetics data were strongly dependent on the initial molar ratios of TrOCs to Fe­(VI). Furthermore, the k app value increases gradually as the reaction proceeds. Several lines of evidence suggested that these phenomena were ascribed to the accumulation of Fe­(IV) and Fe­(V) arising from Fe­(VI) decay. Kinetic models were built and employed to simulate the kinetics of Fe­(VI) self-decay and the kinetics of PMSO degradation by Fe­(VI). The modeling results revealed that PMSO was mainly degraded by Fe­(IV) and Fe­(V) rather than by Fe­(VI) per se and Fe­(V) played a dominant role, which was also supported by the density functional theory calculation results. Given that Fe­(IV) and Fe­(V) have much greater oxidizing reactivity than Fe­(VI), this work urges the development of Fe­(V)/Fe­(IV)-based oxidation technology for efficient degradation of TrOCs.

This paper explores the utility of a discrete singular convolution algorithm for solving certain mechanical problems. Benchmark mechanical systems, including plate vibrations and incompressible¯ows, are employed to illustrate the robustness and to test accuracy of the present algorithm. Numerical results indicate that the present approach is very accurate, ecient and reliable for solving the aforementioned problems. Ó

Amorphous metal–organic frameworks (aMOFs) are an emerging family of attractive materials with great application potential, however aMOFs are usually prepared under harsh conditions and aMOFs with complex compositions and structures are rarely reported. In this work, an aMOF‐dominated nanocomposite (aMOF‐NC) with both structural and compositional complexity has been synthesized using a facile approach. A ligand‐competition amorphization mechanism is proposed based on experimental and density functional theory calculation results. The aMOF‐NC possesses a core–shell nanorod@nanosheet architecture, including a Fe‐rich Fe‐Co‐aMOF core and a Co‐rich Fe‐Co‐aMOF shell in the core–shell structured nanorod, and amorphous Co(OH)2 nanosheets as the outer layer. Benefiting from the structural and compositional heterogeneity, the aMOF‐NC demonstrates an excellent oxygen evolution reaction activity with a low overpotential of 249 mV at 10.0 mA cm−2 and Tafel slope of 39.5 mV dec−1.

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