SiC Nanostructures Toward Biomedical Applications and Its Future Challenges

The present work reviews current research activities for possible applications of silicon carbide (SiC) nanostructures. The main attention is devoted to emerging biomedical applications which can bring a boon for a healthy society. Highlights toward the widespread of SiC nanostructures in new fields of applications are reviewed and explained. This article surveys some of the recent work using SiC nanostructures in biomedical field, sensing, and energy harvesting including a review on nanostructure biocompatibility research to date.

The review article begins with an overview of the state of art of silicon carbide along with their behavior, properties, and applications of SiC in bulk, thin films, and nanoscale forms, respectively. The multidisciplinary applications of SiC nanostructures are also highlighted. Different applications elaborated are as follows: (1) biomedical/nanomedical applications, (2) nanoelectronics, (3) sensing applications, (4) energy harvesting, and (5) other emerging areas. The possibility for employing SiC nanostructures to be accomplished in upgrading the existing devices is suggested based on their properties. This article is concluded with some challenges for future applications.     

Optical fiber based radial polarizer

In this paper we present a new type of optical fiber aiming to radially polarize the electrical field. This special device is composed of a tapered fiber having a classical core while on top of its external surface, radially oriented nanorods are disposed. The tails of the propagated wave are interacting with those radially oriented nanorods. This interaction performs the polarization of the propagated mode into a radial polarization.     

Construction of entropy solutions for one dimensional elastodynamics via time discretisation

It is shown that the variational approximation scheme for one-dimensional elastodynamics given by time discretisation converges, subsequentially, weakly and a.e. to a weak solution which satisfies the entropy inequalities. We also prove convergence under the restriction of positive spatial derivative (for longitudinal motions).     

Multiple solutions of constant sign for nonlinear nonsmooth eigenvalue problems near resonance

In this paper we study a class of nonlinear elliptic eigenvalue problems driven by the p-Laplacian and having a nonsmooth locally Lipschitz potential. We show that as the parameter approaches (= the principal eigenvalue of ) from the right, the problem has three nontrivial solutions of constant sign. Our approach is variational based on the nonsmooth critical point theory for locally Lipschitz functions. In the process of the proof we also establish a generalization of a recent result of Brezis and Nirenberg for C₀¹ versus W₀^1,p minimizers of a locally Lipschitz functional. In addition we prove a result of independent interest on the existence of an additional critical point in the presence of a local minimizer of constant sign. Finally by restricting further the asymptotic behavior of the potential at infinity, we show that for all the problem has two solutions one strictly positive and the other strictly negative.Received: 7 January 2003, Accepted: 12 May 2003, Published online: 4 September 2003Mathematics Subject Classification (2000): 35J20, 35J85, 35R70     

Variational Approach to Uniform Rigid Rotation of Ginzburg—Landau Vortices

Time periodic solutions for the hyperbolic gauged Ginzburg–Landau system, with spatial domain the unit disc, are shown to exist. Time periodic solutions representing bound states of vortices rotating about one another have been previously obtained in the near self-dual limit, using perturbative techniques. In contrast, we here take a variational approach, the solutions being obtained as critical points of an indefinite functional. We consider a special class of solutions which map out, uniformly in time, an orbit of the rotation group SO(2). It is shown that in the limit of large coupling constant the solutions have nontrivial time dependence or, as is shown to be equivalent, are not radially symmetric in any gauge.     

Prospects and challenges in designing photocatalytic particle suspension reactors for solar fuel processing

Photocatalytic approaches for the production of solar hydrogen or hydrocarbons are interesting as they provide a sustainable alternative to fossil fuels. Research has been focused on water splitting and on the synthesis of photocatalyst materials and compounds, and their characterization. The material-related challenges include the synthesis and design of photocatalysts that can absorb visible light at a high quantum efficiency, cocatalysts that are selective and can accelerate the reduction and/or oxidation reactions, and protection layers that facilitate migration of the minority carriers to the surface-active sites while reducing charge recombination and photo-corrosion. Less attention has been paid to the conceptual design of reactors, and how design and coupled transport can affect the material choice and requirements. This perspective discusses the various possible conceptual designs for particle suspension reactors and the related implications on the material requirements to achieve high energy conversion efficiencies. We establish a link between the thermodynamic limits, materials requirements, and conceptual reactor designs, quantify changes in material requirements when more realistic operation and losses are considered, and compare the theory-derived guidelines with the ongoing materials research activity.

This perspective discusses the various possible conceptual designs for particle suspension reactors and the related implications on the material and reactor requirements to achieve high STH conversion efficiencies.     

Synthesis of the hydroxide cluster [Al13(μ3-OH)6(μ-OH)18(H2O)24]15+ from an aqueous solution

A scalable synthesis of the "flat" tridecameric inorganic cluster [Al(13)(μ(3)-OH)(6)(μ-OH)(18)(H(2)O)(24)](15+) has been realized by treating an aqueous aluminum nitrate solution with a zinc-metal powder at room temperature. Single crystals and polycrystalline samples are readily obtained in yields exceeding 55% relative to the starting reagent Al(NO(3))(3). Products have been characterized by X-ray diffraction and solid-state (27)Al MAS and MQMAS NMR.     

Catching gaseous SO2 in cone-type lanthanide complexes: an unexpected coordination mode for SO2 in f-element chemistry

Easy come, easy go: the first molecular SO(2) complexes of the lanthanides (Ln=Sm, Eu) have been prepared. The compounds can reversibly coordinate gaseous SO(2). Concomitant with the addition and removal of SO(2), the color of the complexes changes reversibly. The structures of the SO(2) compounds could be confirmed in solution and in the solid state.     

Inhomogeneous multiscale dynamics in harmonic lattices

We use projection operators to address the coarse-grained multiscale problem in harmonic systems. Stochastic equations of motion for the coarse-grained variables, with an inhomogeneous level of coarse graining in both time and space, are presented. In contrast to previous approaches that typically start with thermodynamic averages, the key element of our approach is the use of a projection matrix chosen both for its physical appeal in analogy to mechanical stability theory and for its algebraic properties. We show that thermodynamic equilibrium can be recovered and obtain the fluctuation dissipation theorem a posteriori. All system-specific information can be computed from a series of feasible molecular dynamics simulations. We recover previous results in the literature and show how this approach can be used to extend the quasicontinuum approach and comment on implications for dissipative particle dynamics type of methods. Contrary to what is assumed in the latter models, the stochastic process of all coarse-grained variables is not necessarily Markovian, even though the variables are slow. Our approach is applicable to any system in which the coarse-grained regions are linear. As an example, we apply it to the dynamics of a single mesoscopic particle in the infinite one-dimensional harmonic chain.     

KINETICS OF SIMIAN VIRUS 40 AND LAMBDA INACTIVATION BY PHOTOADDITION OF PSORALEN DERIVATIVES

Abstract The kinetics of psora/en photoinactivation of two distinct DNA viruses, bacteriophage λ and the papovavirus SV40 were investigated. When λ is treated with near ultraviolet light (UVA, 320-400 nm) and 4,5',8-trimethylpsoralen (TMP) at 1 μg/m/, the phage is rapidly inactivated. The survival curve exhibits a distinct shoulder indicating second or higher-order kinetics. SV40, on the other hand, is much more resistant to psoralen photoinactivation and the survival curve is linear, reflecting first order or'pseudo-first order'kinetics. Two TMP derivatives with increased solubility in aqueous solutions, 4'-aminomethyl-TMP and 4'-hydroxymethyl-TMP, were similarly tested. In both virus systems, TMP was much more effective. In experiments designed to examine the role of psoralen cross-link formation in virus inactivation, treated samples were irradiated a second time in the absence of drug. Since reirradiation causes a decline in λ infectivity as great as that observed in continuously irradiated samples, cross-links are implicated as the primary lethal event. In the case of SV40, the results of such a protocol suggest that both monoadducts and cross-links may be lethal or that monoadduct formation may be rate-limiting.