The emerging field of graphene brings together scientists and engineers as the discovered fundamental properties and effects encountered in this new material can be rapidly exploited for practical applications. There is potential for a two-dimensional graphene-based technology and recent works have already demonstrated the utility of graphene in building nanoelectromechanical systems, complex electronic circuits, photodetectors and ultrafast lasers. The state-of-the-art of substrate-suported graphene growth, and the current fundamental understanding of the electromechanical properties of graphene and graphene nanoribbons, represent important knowledge for developing new applications.

A system where a Bose-Einstein condensate of exciton-polaritons coexists with a Fermi gas of electrons has been recently proposed as promising for realization of room-temperature superconductivity. In order to find the optimum conditions for exciton and exciton-polariton mediated superconductivity, we studied the attractive mechanism between electrons of a Cooper pair mediated by the exciton and exciton-polariton condensate. We also analyzed the gap equation that follows. We specifically examined microcavities with embedded n-doped quantum wells as well as coupled quantum wells hosting a condensate of spatially indirect excitons, put in contact with a two-dimensional electron gas. An effective potential of interaction between electrons was derived as a function of their exchanged energy ℏω,taking into account the retardation effect that allows two negatively charged carriers to feel an attraction. In the polariton case, the interaction is weakly attractive at long times, followed by a succession of strongly attractive and strongly repulsive windows. Strikingly, this allows high critical temperature solutions of the gap equation. An approximate three-steps potential is used to explain this result that is also obtained numerically. The case of polaritons can be compared with that of excitons, which realize the conventional scenario of high-T_c superconductivity where a large coupling strength accounts straightforwardly for the high critical temperatures. Excitons are less advantageous than polaritons but may be simpler systems to realize experimentally. It is concluded that engineering of the interaction in these peculiar Bose-Fermi mixtures is complex and sometimes counter-intuitive, but leaves much freedom for optimization, thereby promising the realization of high-temperature superconductivity in multilayered semiconductor structures.

Surface enhanced Raman scattering (SERS) is an optical spectroscopy technique with single molecule sensitivity and chemical specificity. The electromagnetic enhancement mechanism of SERS is facilitated by the localized surface plasmons of metallic nanostructures utilized in experiments. The magnitude of the local optical field created by the plasmonic nanostructure depends on parameters such as size, shape, morphology, arrangement, and local environment of the nanostructure. By tuning these parameters, electromagnetic hot spots can be created to facilitate ultra-sensitive, subwavelength SERS detection platforms. In recent years, there have been a number of innovations in nanofabrication and synthesis of plasmonic nanostructures. This has led to a variety of plasmonic nano-architectures that can be harnessed for SERS. Recently investigated plasmonic nanostructures in the context of SERS include nanosphere dimers, individual nanocubes, nanotriangular arrays, nano-pyramid shells, individual and assembly of nanorods, nanowires, and nanotips, and some unconventional nano-architectures. Challenges in fundamental and application aspects of SERS remain for future research.

Research is turning toward nanotechnology for solutions to current limitations in biomedical imaging and analytical detection applications. New to fluorescent nanomaterials that could help advance such applications are protein-stabilized gold nanoclusters. They are potential candidates for imaging agents and sensitive fluorescence sensors because of their biocompatibility and intense photoluminescence. This review discusses the strategy for synthesizing fluorescent protein-gold nanoclusters and the characterization methods employed to study these systems. Optical properties and relevant light-emitting applications are reported to present the versatility of protein-gold nanoclusters. These new bio-nano hybrids are an exciting new system that remains to be explored in many aspects, especially regarding the determination of gold nanocluster local structure and the enhancement of quantum yields. Understanding how to finely tune the optical properties will be pivotal for improving fluorescence imaging and other nanocluster applications. There is a promising future for fluorescent protein-gold nanoclusters as long as research continues to uncover fundamental structure-property relationships.

Deoxyribonucleic acid (DNA) chains can be engineered for diverse nanophotonics applications by the insertion of molecular groups in different spatial configurations. DNA chains can be assembled into wire-like structures, origami structures, photonic crystal-like assemblies, liquid-crystal phases, and thin films. These structures can be made to serve as scaffolds for the organization of various organic molecules and nanoparticles. The properties of nanostructures can be modified by the use of DNA and DNA modified by the surfactants.

Major improvements in fabrication techniques at the nanoscale during the last two decades enable us to exploit and control nanoscale phenomena such as the localized surface plasmons (LSP) provided by metallic nanoparticles (MNP). The large enhancement of the electromagnetic field due to plasmonic effects increases drastically the response of any analyte located close to or adsorbed on MNPs, which opens ways for detection of very low concentration of analytes and sensor miniaturization. However, the efficiency of such nanosensors requires a precise control of the optical properties of the MNPs since it strongly depends on their geometrical properties. Such precision can be reached by nanolithography techniques. The parameters that govern the near field enhancement include the geometrical parameters of the MNPs (size, shape, and gap), the LSP characteristics (near field decay length and resonance position) and the excitation parameters (excitation wavelength and associated electric field polarization). Nanolithography techniques used for surface nanostructuring include optical, focused electron and ion beams, nanoimprint and nanosphere lithographies. Nanosensor fabricated lithographically exploit localized surface plasmon resonance, surface enhanced Raman scattering, and surface enhanced fluorescence.

Two different formalisms for the homogenization of composite materials containing oriented ellipsoidal particles of isotropic dielectric materials are being named after Bruggeman. Numerical studies reveal clear differences between the two formalisms which may be exacerbated: (i) if the component particles become more aspherical, (ii) at mid-range values of the volume fractions, and (iii) if the homogenized component material is dissipative. Only the correct Bruggeman formalism uses the correct polarizability density dyadics of the component particles in the homogenized composite material (HCM) and is directly derivable from the frequency-domain Maxwell postulates specialized for the HCM.

Fluorescence of gold nanocubes is investigated down to the single-particle level using time-correlated single photon (SP) counting techniques with a combined confocal and atomic force microscopy system. In comparison with most fluorophores, gold nanocubes exhibit nonblinking and nonbleaching behavior at ambient environment with much faster fluorescence decay. Also, the photon statistics of single gold nanocubes follows a Poissonian distribution, unlike the SP emission characteristics of single semiconducting quantum dots. Therefore, from the single-particle perspective, the fluorescence of gold nanocubes is attributed to the radiative emission from excited localized surface plasmons.

Time delays in emission of resonantly trapped light in magnetite microspheres dispersed in a ferrofluid were measured for three different sphere sizes. The time delay was found to vary randomly. The effect of the size of microspheres on the probability distribution was determined. Analysis of the data showed that the statistics of the time delay is best described by a Levy distribution.

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Much, but not all, research today is financially supported by governments. In democratic dispensations, that means that a significant portion of research is funded by the taxpayers. Since the taxpayers have paid for the research upfront, should they not receive the research results for free? This argument underlies the concept of open-access publication of research results that is being increasingly demanded by governments and public-interest groups.