Asymptotic properties of a stochastic nonautonomous competitive system with impulsive perturbations

Abstract In this paper, a generalized nonautonomous stochastic competitive system with impulsive perturbations is studied. By the theories of impulsive differential equations and stochastic differential equations, we have established some asymptotic properties of the system, such as the extinction, nonpersistence and persistence in the mean, weak persistence and stochastic permanence and so on. In order to show the correctness and feasibility of the theoretical results, several numerical examples are presented. Finally, the effects of different white noise perturbations and different impulsive perturbations are discussed and illustrated

Improved Stability Criteria for Markovian Jump Systems with Time-Varying Delays

The delay-dependent stochastic stability problem of Markovian jump systems with time-varying delays is investigated in this paper. Though the Lyapunov-Krasovskii functional is general and simple, less conservative results are derived by using the convex combination method, improved Wirtinger’s integral inequality, and a slack condition on Lyapunov matrix. The obtained results are formulated in terms of linear matrix inequalities (LMIs). Numerical examples are provided to verify the effectiveness and superiority of the presented results

Semiconductor Solid-Solution Nanostructures: Synthesis, Property Tailoring, and Applications

The innovation of band-gap engineering in advanced materials caused by the alloying of different semiconductors into solid-solution nanostructures provides numerous opportunities and advantages in optoelectronic property tailoring. The semiconductor solid-solution nanostructures have multifarious emission wavelength, adjustability of absorption edge, tunable electrical resistivity, and cutting-edge photoredox capability, and these advantages can be rationalized by the assorted synthesis strategies such as, binary, ternary, and quaternary solid-solutions. In addition, the abundance of elements in groups IIB, IIIA, VA, VIA, and VIIA provides sufficient room to tailor-make the semiconductor solid-solution nanostructures with the desired properties. Recent progress of semiconductor solid-solution nanostructures including synthesis strategies, structure and composition design, band-gap engineering related to the optical and electrical properties, and their applications in different fields is comprehensively reviewed. The classification, formation principle, synthesis routes, and the advantage of semiconductor solid-solution nanostructures are systematically reviewed. Moreover, the challenges faced in this area and the future prospects are discussed. By combining the information together, it is strongly anticipated that this Review may shed new light on understanding semiconductor solid-solution nanostructures while expected to have continuous breakthroughs in band-gap engineering and advanced optoelectronic nanodevices

New Dibenzo-α-pyrone Derivatives with α-Glucosidase Inhibitory Activities from the Marine-Derived Fungus Alternaria alternata

Three new dibenzo-α-pyrone derivatives, alternolides A–C (1–3), and seven known congeners (4–10) were isolated from the marine-derived fungus of Alternaria alternata LW37 assisted by the one strain-many compounds (OSMAC) strategy. The structures of 1–3 were established by extensive spectroscopic analyses, and their absolute configurations were determined by modified Snatzke′s method and electronic circular dichroism (ECD) calculations. Compounds 6 and 7 showed good 1,1-diphenyl-2-picrylhydrazyl (DPPH) antioxidant scavenging activities with IC50 values of 83.94 ± 4.14 and 23.60 ± 1.23 µM, respectively. Additionally, 2, 3 and 7 exhibited inhibitory effects against α-glucosidase with IC50 values of 725.85 ± 4.75, 451.25 ± 6.95 and 6.27 ± 0.68 µM, respectively. The enzyme kinetics study indicated 2 and 3 were mixed-type inhibitors of α-glucosidase with Ki values of 347.0 and 108.5 µM, respectively. Furthermore, the interactions of 2, 3 and 7 with α-glucosidase were investigated by molecular docking

Cerium oxide nanotubes prepared from cerium hydroxide nanotubes

The production of Ce(OH)3 nanotubes, and the formation of CeO2 nanotubes via controlled annealing of the as-formed Ce(OH) 3 nanotubes were discussed. Cerium hydroxide nanotubes was synthesized by hydrothermal treatment of CeCl3 with a 12 M NaOH solution at temperatures ranging from 100 to 150 °C. The morphology and structure of the as-synthesized products were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). All the Ce(OH) 3 crystals synthesized revealed a 1D structure under the conditions used.</p

Synthesis and field emission of carbon nanotubular fibers doped with high nitrogen content

Nitrogen-doped carbon nanotubular fibers with a very high nitrogen concentration (∼20 at.%) were synthesized through the aerosol-assisted decomposition of dimethylformamide in the presence of catalyst. The synthesized fibers process a novel “pearl necklace-like” morphology and exhibit an excellent field emission performance.</p

Synthesis, characterization and field-emission properties of bamboo-like β-SiC nanowires

Single-crystalline bamboo-like β-SiC nanowires with hexagonal cross-sections were synthesized by thermal evaporation of mixed SiO+C+GaN powders in an Ar atmosphere. The as-synthesized nanowires were studied by x-ray diffraction, scanning electron microscopy and transmission electron microscopy. Studies found that the as-synthesized SiC nanowires are composed of hexagonal stems decorated with larger diameter knots along their whole length with the growth direction. The growth of bamboo-like SiC nanowires is governed by the vapour-liquid-solid mechanism. Field-emission properties of the peculiar nanostructures were also explored, showing a turn-on field of about 10.1 V μm-1.</p