Silver nanowires for photonics applications

Although silver nanowires as plasmonic components have been investigated extensively in both theoretical and experimental studies, a systematic study is still lacking. In this work, a review is given to explain some basic features of experimentally prepared nanowires and their optical properties in different situations, such as waveguides, resonators, and antennas. The review also lists several possible applications of nanowires for enhanced light‐emitting, photonic device fabrication, sensors, lasers, and nonlinear optics. Combined with the merits of both nanowires and surface plasmon polaritons, silver nanowires are certain to show their potential in photonics in the near future.     

A random integral quadrature method for numerical analysis of the second kind of Volterra integral equations

In this paper, a novel meshless technique termed the random integral quadrature (RIQ) method is developed for the numerical solution of the second kind of the Volterra integral equations. The RIQ method is based on the generalized integral quadrature (GIQ) technique, and associated with the Kriging interpolation function, such that it is regarded as an extension of the GIQ technique. In the GIQ method, the regular computational domain is required, in which the field nodes are scattered along straight lines. In the RIQ method however, the field nodes can be distributed either uniformly or randomly. This is achieved by discretizing the governing integral equation with the GIQ method over a set of virtual nodes that lies along straight lines, and then interpolating the function values at the virtual nodes over all the field nodes which are scattered either randomly or uniformly. In such a way, the governing integral equation is converted approximately into a system of linear algebraic equations, which can be easily solved.     

The protection zone for biological population in random environment

A biomathematical model is described by stochastic differential equations with Markovian switching. The long‐time dynamical properties are studied both theoretically and numerically. Results show that both the persistence and extinction have close relationship with environmental noises (white and color noises). These results are of important biological significance for biological conservation. Copyright © 2012 John Wiley & Sons, Ltd.     

On a nonlocal elliptic problem arising in the confinement of a plasma in a current carrying stellarator

This paper deals with a nonlocal free boundary problem arising in the study of the dynamics of the confinement of a plasma in a Stellarator device. The free boundary represents the separation between the plasma and vacuum regions, and the nonlocal term involves the notions of relative rearrangement and monotone rearrangement. We establish some new properties on the decreasing rearrangement that can be used to prove the convergence of the approximate problem, and then prove the existence of solutions by Galerkin method. Copyright © 2013 John Wiley & Sons, Ltd.     

Ultrasonic-assisted synthesis of highly dispersed MoO3 nanospheres using 3-mercaptopropyltrimethoxysilane

With ultrasonic irradiation as assistance, highly dispersed MoO(3) nanospheres were synthesized using silane coupling agent 3-mercaptopropyltrimethoxysilane HS-(CH(2))(3)Si(OCH(3))(3) (MPTS) as figuration agent. The results of X-ray powder diffractometer (XRD) showed that the precursor was hexagonal molybdenum oxide hydrate (MoO(3).0.55H(2)O). It was converted into orthorhombic MoO(3) after annealed at 400 degrees C for 2h. Transmission electron microscopy (TEM) showed that MoO(3).0.55H(2)O and MoO(3) nanoparticles were spherical with particle-size distribution of ca. 30-80 nm and 25-75 nm, respectively. Results indicated that MPTS and ultrasonic irradiation played important role in formation of highly dispersed MoO(3) nanospheres. X-ray photoelectron spectroscopy (XPS) was also adopted to confirm the growth mechanism. The possible cause of formation was based on dispersion function of ultrasonic irradiation and figuration of MPTS.     

Random Sierpinski network with scale-free small-world and modular structure

In this paper, we define a stochastic Sierpinski gasket, on the basis of which we construct a network called random Sierpinski network (RSN). We investigate analytically or numerically the statistical characteristics of RSN. The obtained results reveal that the properties of RSN is particularly rich, it is simultaneously scale-free, small-world, uncorrelated, modular, and maximal planar. All obtained analytical predictions are successfully contrasted with extensive numerical simulations. Our network representation method could be applied to study the complexity of some real systems in biological and information fields.     

Regioselective α-benzylation of 3-iodoazetidine via Suzuki cross-coupling

An efficient protocol for the synthesis of α-benzyl azetidines starting from benzylboronic acid pinacol ester derivatives and 3-iodoazetidine was developed. A wide range of α-benzyl azetidine derivatives were obtained in moderate to good yields with high regioselectivity (>99%).     

Leaving Group Assisted Strategy for Photoinduced Fluoroalkylations Using N‐Hydroxybenzimidoyl Chloride Esters

Redox‐active esters (RAEs) as alkyl radical precursors have been extensively developed for C?C bond formations. However, the analogous transformations of fluoroalkyl radicals from the corresponding acid or ester precursors remain challenging because of the high oxidation potential of the fluoroalkyl carboxylate anions. The newly developed N‐hydroxybenzimidoylchloride (NHBC) ester provides a general leaving group assisted strategy to generate a portfolio of fluoroalkyl radicals, and can be successfully applied in photoinduced decarboxylative hydrofluoroalkylation and heteroarylation of unactivated olefins. In addition, DFT calculations revealed that the NHBC ester proceeds by the fluorocarbon radical pathway, whereas other well‐known RAEs proceed by the nitrogen radical pathway.     

Unprecedented [5.5.5.6]Dioxafenestrane Ring Construction in Fungal Insecticidal Sesquiterpene Biosynthesis

Fenestranes, a specific class of natural products, contain four fused rings that share a central quaternary carbon atom. The fungal natural product penifulvin A ( 1 ) is a potent insecticidal sesquiterpene that features the [5.5.5.6]dioxafenestrane ring. Although the chemical synthesis of 1 has been achieved recently, the enzymes catalysing the cyclization and oxidation of FPP to 1 remain unknown. In this work, we identified a concise pathway that uses only three enzymes to produce 1 . A new sesquiterpene cyclase (PeniA) generates the angular triquinane scaffold silphinene ( 6 ). A cytochrome P450 (PeniB) and a flavin‐dependent monooxygenase (PeniC) catalyse a series of oxidation reactions to transform 6 into 1 , including oxidation of the C15 methyl group to a carboxylate moiety, oxidative coupling of the C15 carboxylate and the C1‐C2 olefin to form a γ‐lactone, and Baeyer–Villiger oxidation to form a δ‐lactone. Our results demonstrate the highly concise and efficient ways in which fungal biosynthetic pathways can generate complex sesquiterpene scaffolds.     

Directed Evolution of a Bacterial Laccase (CueO) for Enzymatic Biofuel Cells

Escherichia coli's copper efflux oxidase (CueO) has rarely been employed in the cathodic compartment of enzymatic biofuel cells (EBFCs) due to its low redox potential (0.36 V vs. Ag/AgCl, pH 5.5) towards O₂ reduction. Herein, directed evolution of CueO towards a more positive onset potential was performed in an electrochemical screening system. An improved CueO variant (D439T/L502K) was obtained with a significantly increased onset potential (0.54 V), comparable to that of high‐redox‐potential fungal laccases. Upon coupling with an anodic compartment, the EBFC exhibited an open‐circuit voltage (V_oc) of 0.56 V. Directed enzyme evolution by tailoring enzymes to application conditions in EBFCs has been validated and might, in combination with molecular understanding, enable future breakthroughs in EBFC performance