Highly-active,metal-free,carbon-based ORR cathode for efficient organics removal and electricity generation in a PFC system

A highly-active,metal-free,carbon-based oxygen reduction reaction(ORR) cathode,i.e.,graphitized Ndoped carbon felt(GNCF),was prepared,for the first time,by in-situ modifying the doping species of polyacrylonitrile(PAN)-based carbon felt(CF) via a facile annealing process in Ar atmosphere.It was applied for dramatically enhanced organics degradation and electricity generation in a photocatalytic fuel cell(PFC) system.The GNCF showed enhanced specific surface area,improved graphitization and raised ratio of graphitic N,therefore resulting in excellently improved ORR performance compared to the CF.When applying the GNCF as a cathode in a PFC system,the proposed PFC showed significant improvement in degrading various model organic contaminants and outputing electricity simultaneously when compared with the PFC with CF.For instance,the apparent rate constant and electricity output efficiency showed ～10.6 times and ～7.2 times,respectively,improvement when using rhodamine B as model waste.Further improved performance was also achieved by aeration of air or O_2 due to the fu rther enhanced ORR.The proposed PFC was also efficient in a wide pH,and kept outsta nding stability in long-term utilization.     

An Endogenous Prompting Mechanism for Sulfur Conversions Via Coupling with Polysulfides in Li−S Batteries

The sluggish kinetics process and shuttling of soluble intermediates present in complex conversion between sulfur and lithium sulfide severely limit the practical application of lithium-sulfur batteries. Herein, by introducing a designated functional organic molecule to couple with polysulfide intermediators, an endogenous prompting mechanism of sulfur conversions has thus been created leading to an alternative sulfur-electrode process, in another words, to build a fast “internal cycle” of promotors that can promote the slow “external cycle” of sulfur conversions. The coupling-intermediators between the functional organic molecule and polysulfides, organophosphorus polysulfides, to be the “promotors” for sulfur conversions, are not only insoluble in the electrolyte but also with higher redox-activity. So the sulfur-electrode process kinetics is greatly improved and the shuttle effect is eliminated simultaneously by this strategy. Meanwhile, with the endogenous prompting mechanism, the morphology of the final discharge product can be modified into a uniform covering film, which is more conducive to its decomposition when charging. Benefiting from the effective mediation of reaction kinetics and control of intermediates solubility, the lithium-sulfur batteries can act out excellent rate performance and cycling stability.     

Activated carbon spheres (ACS)@SnO2@NiO with a 3D nanospherical structure and its synergistic effect with AHP on improving the flame retardancy of epoxy resin

A novel activated carbon spheres (ACS)@SnO₂@NiO hierarchical hybrid architecture was first synthesized and applied for enhancing the flame retardancy of epoxy (EP) resin via a cooperative effect. Herein, using activated carbon microspheres as the template, SnO₂ and NiO nanospheres were successively anchored to it by a sedimentation‐calcination strategy. The well‐designed ACS@SnO₂@NiO significantly enhanced the flame retardancy for consistency of EP composites, as demonstrated by thermogravimetric and cone calorimeter experiments. For instance, the incorporation of 2 wt% ACS@SnO2@NiO decreased by 15.5% maximum in the total smoke production, accompanying the higher graphitized char layer. In addition, the synergetic mechanism of flame retardancy between ACS@SnO₂@NiO and aluminum hypophosphite (AHP) was investigated. The obtained sample satisfied the UL‐94 V‐0 rating with a 5.0 wt% addition of AHP and ACS@SnO₂@NiO (the ratio of the mass fraction of AHP to ACS@SnO₂@NiO is 4.5:0.5). Notably, the incorporation of AHP and ACS@SnO₂@NiO resulted in a significant decrease in the fire hazard properties of EP resin; for instance, 4.5AHP‐0.5ACS@SnO₂@NiO/EP resulted in a maximum decrease of 32.4% in the total smoke production as compared with that of pure EP resin. It should be noted that the improved flame‐retardant performance for the EP composites is primarily attributed to the synergistic effect of ACS@SnO₂@NiO and AHP in promoting the formation of residual char in the condensed phase.     

Long-time behaviour of ferromagnetic spin chain equation: global attractor and its dimension

In this paper the authors consider the initial boundary value problem of the ferromagnetic spin chain equation and prove the existence of the global attractor and finiteness of the Hausdorff and the fractal dimensions of the attractor. © 1997 B. G. Teubner Stuttgart–John Wiley & Sons Ltd.     

Asymptotic Behaviour of Blow-up for Solutions of Semilinear Reaction-diffusional Systems

In this paper, we consider Lhe asymptotic behaviour of the solutions or semilinear reaction-diffusional systems and obtain the growth rate.     

Asperchalasine A,a Cytochalasan Dimer with an Unprecedented Decacyclic Ring System,from Aspergillus flavipes

Asperchalasine A ( 1 ), the first cytochalasan dimer featuring a unique decacyclic 5/6/11/5/5/6/5/11/6/5 ring system consisting of 20 chiral centers, was isolated from the culture broth of Aspergillus flavipes. Three biogenetically related intermediates, asperchalasines B–D ( 2 – 4 ), were also isolated. Their structures, including their absolute configurations, were elucidated using a combination of HRESIMS, NMR, ECD, molecular modeling, and single‐crystal X‐ray diffraction techniques. Compound 1 , which possesses an unprecedented 13‐oxatetracyclo[7.2.1.1^2,5.0^1,6]tridec‐8,12‐dione core structure, is the first example of a dimeric cytochalasan alkaloid. The biogenetic pathways of 1 – 4 were described starting from the co‐isolated compounds 5 and 6 . More importantly, 1 induced significant G1‐phase cell cycle arrest by selectively inhibiting cyclin A, CDK2 and CDK6 in cancerous, but not normal, cells, highlighting it as a potentially selective cell cycle regulator against cancer cells.     

Study of liquid–solid catalytic reaction of epichlorohydrin with sodium butyrate in the presence of tetrabutylammonium bromide

The liquid–solid catalytic reaction of epichlorohydrin and sodium butyrate with tetrabutylammonium bromide as a phase transfer catalyst was studied in this paper. The shrinking core model was applied. The analysis of the reaction based on the kinetic model showed a reaction-controlled regime at temperatures varying from 90 to 100°C. The exterior diffusivity was removed between 300 and 400 rpm. The internal diffusivity was removed when the particle size was 2 × 10^–4 m. Reaction rate constants were calculated at different temperatures. The correlation was obtained when the proposed kinetic model was applied to all the experimental data for predictive evaluations and the activation energy was 37.01 kJ mol^–1.     

On generalized CS-modules

An S-closed submodule of a module M is a submodule N for which M/N is nonsingular. A module M is called a generalized CS-module (or briefly, GCS-module) if any S-closed submodule N of M is a direct summand of M. Any homomorphic image of a GCS-module is also a GCS-module. Any direct sum of a singular (uniform) module and a semi-simple module is a GCS-module. All nonsingular right R-modules are projective if and only if all right R-modules are GCS-modules.     

Graded index photonic crystals: A review

A new type of photonic crystal (PC) named graded index (GRIN) PC was proposed by E. Centeno in 2005. It is obtained by appropriately modifying the parameters of a regular PC, thus resulting in gradual index variation. Many applications are inspired by this notion. This review will introduce different ways of designing GRIN PCs from both theoretical and experimental point of views. Some typical applications based on GRIN PCs are presented, followed by the focusing mechanism of GRIN PC.

     

A mixing propagation model of computer viruses and countermeasures

Based on the CMC antivirus strategy proposed by Chen and Carley, a mixing propagation model of computer viruses and countermeasures is suggested. This model has two potential virus-free equilibria and two potential endemic equilibria. The existence and global stability of these equilibria are fully investigated. From the obtained results it can be deduced that the CMC strategy is efficacious in deracinating viruses.