Unidirectional and wavelength-selective photonic sphere-array nanoantennas

We design a photonic sphere-array nanoantenna (NA) exhibiting both strong directionality and wavelength selectivity. Although the geometric configuration of the photonic NA resembles a plasmonic Yagi-Uda NA, it has different working principles and, most importantly, reduces the inherent metallic loss from plasmonic elements. For any selected optical wavelength, a sharp Fano resonance by the reflector is tunable to overlap spectrally with a wider dipole resonance by the sphere-chain director, leading to high directionality. This Letter provides design principles for directional and selective photonic NAs, which are particularly useful for photon detection and spontaneous emission manipulation. © 2012 Optical Society of America.published_or_final_versio

The numerical steepest descent path method for calculating physical optics integrals on smooth conducting quadratic surfaces

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Heavy metal concentrations in ceiling fan and roadside car park dust collected from residential colleges in Universiti Putra Malaysia, Serdang, Selangor

In this study, dust samples were collected from 4 residential colleges (K2, K5, KOSAS and K10) in UniversitiPutra Malaysia (UPM) Serdang, Selangor. The samples were collected from ceiling fans and car parksroadside dust. Sand dust on top of the car park cover were collected using polyethylene brush, tray and keptin a polyethylene bag. Dust from ceiling fan on the first floor was collected and put into a polyethylene bag.The dust samples collected were analysed for the concentrations of Cd, Cu, Fe, Ni and Zn. It was found thatK5 [Cu (62.94 ± 0.77 µg/g dw), Fe (1802.40 ± 9.81 µg/g dw), and Zn (253.34 ± 22.76 µg/g dw) of car parkdust; Zn (997.20 ± 16.10 µg/g dw) (of ceiling fan dust] and K10 [Ni (26.88 ± 1.84 µg/g dw) and Zn (199.77± 6.64 µg/g dw) of car park dust; Cu (468.55 ± 3.67 µg/g dw), Ni (83.96 ± 0.75 µg/g dw), and Fe (3131.58 ±27.01 µg/g dw) of ceiling fan dust] exhibited elevated concentrations of heavy metals that might be related tovehicular activities as compared to K2 and KOSAS. In general, ceiling fan dust had significantly (P< 0.05)higher concentrations of heavy metals than the car park dust. In comparison to other reported studies in theliterature, the maximum levels of Ni and Cu were comparable or higher than those reported for major cities inthe world. Hence, more monitoring studies should be conducted in the future to check for metal contaminationin the dust, as this can serve as an atmospheric indicator of heavy metal pollution

Evolved orthogonal ribosomes enhance the efficiency of synthetic genetic code expansion

In vivo incorporation of unnatural amino acids by amber codon suppression is limited by release factor-1–mediated peptide chain termination. Orthogonal ribosome-mRNA pairs function in parallel with, but independent of, natural ribosomes and mRNAs. Here we show that an evolved orthogonal ribosome (ribo-X) improves tRNA_(CUA)-dependent decoding of amber codons placed in orthogonal mRNA. By combining ribo-X, orthogonal mRNAs and orthogonal aminoacyl-tRNA synthetase/tRNA pairs in Escherichia coli, we increase the efficiency of site-specific unnatural amino acid incorporation from ∼ 20% to >60% on a single amber codon and from 20% on two amber codons. We hypothesize that these increases result from a decreased functional interaction of the orthogonal ribosome with release factor-1. This technology should minimize the functional and phenotypic effects of truncated proteins in experiments that use unnatural amino acid incorporation to probe protein function in vivo

Exterior optical cloaking and illusions by using active sources: a boundary element perspective

Recently, it was demonstrated that active sources can be used to cloak any objects that lie outside the cloaking devices [Phys. Rev. Lett. \textbf{103}, 073901 (2009)]. Here, we propose that active sources can create illusion effects, so that an object outside the cloaking device can be made to look like another object. invisibility is a special case in which the concealed object is transformed to a volume of air. From a boundary element perspective, we show that active sources can create a nearly "silent" domain which can conceal any objects inside and at the same time make the whole system look like an illusion of our choice outside a virtual boundary. The boundary element method gives the fields and field gradients (which can be related to monopoles and dipoles) on continuous curves which define the boundary of the active devices. Both the cloaking and illusion effects are confirmed by numerical simulations

Understanding and Quantifying Cleaning Processes Using Fluid Dynamic Gauging

Computational fluid dynamics (CFD) has been used to analyse the flow patterns generated by the fluid dynamic gauging (FDG) technique in order to allow that technology to give simultaneous measurements of fouling layer thickness and incipient strength (via breakage). Stress field predictions were generated by solving the governing Navier-Stokes equations for these quasi-laminar flows using the numerical solver FastflowTM and validated by comparison with experimental hydrostatic pressure data. Enhanced FDG was used to study the removal of a tomato paste soil, which had been characterised by Liu et al. (2002) using a micro-manipulation technique. Deposit strength measurements gave clear indication of increases on ageing via baking and are compared with those reported by Liu et al

Effect of calcination temperature on electrical properties of Nd0.7Ba0.3MnO3

In this work, Nd0.7Ba0.3MnO3 was synthesized via cryo-milling method to investigate the effect of calcination temperature on the structure, microstructure, magnetic and electrical properties. XRD analysis revealed all samples can be indexed to orthorhombic structure systems with Imma space group accompany with some minor phases of Mn2O4 and BaMnO3. FESEM analysis confirmed that a slight increase in the grain size from 117.4 nm (600°C), 119.5 nm (700°C), 121.0 nm (800°C), 123.1 nm (900°C) to 138.4 nm (1000°C) was observed when different calcination temperature was applied. Four Point Probe measurements showed that all samples are in paramagnetic insulating region and TMIT is lower than 20K. Resistivity increase when grain size reduces due to increase of effective grain boundary that weakens the electron hopping process via double exchange mechanism. Beside, a drastic increase of resistivity also observed due to present of minor secondary phase (BaMnO3) in sample C9

Ground-state van der Waals forces in planar multilayer magnetodielectrics

Within the frame of lowest-order perturbation theory, the van der Waals potential of a ground-state atom placed within an arbitrary dispersing and absorbing magnetodielectric multilayer system is given. Examples of an atom situated in front of a magnetodielectric plate or between two such plates are studied in detail. Special emphasis is placed on the competing attractive and repulsive force components associated with the electric and magnetic matter properties, respectively, and conditions for the formation of repulsive potential walls are given. Both numerical and analytical results are presented.Comment: 16 pages, 8 figures, minor correction