59 research outputs found
Boundary-Induced Embedded Eigenstate in a Single Resonator for Advanced Sensing
Electromagnetic embedded eigenstates, also known as bound states in the
continuum (BICs), hold a great potential for applications in sensing, lasing,
enhanced nonlinearities and energy harvesting. However, their demonstrations so
far have been limited to large-area periodic arrays of suitably tailored
elements, with fundamental restrictions on the overall footprint and
performance in presence of inevitable disorder. In this work, we demonstrate a
BIC localized in a single subwavelength resonator obtained by suitably
tailoring the boundaries around it, enabling a new degree of control for
on-demand symmetry breaking. We experimentally demonstrate how boundary-induced
BICs open exciting opportunities for sensing by tracing the dissolution of NaCl
in water, determining evaporation rates of distilled and saltwater with a
resolution of less than 1e-6 L using a tabletop experimental setup
Interactions of nanorod particles in the strong coupling regime
The plasmon coupling in a nanorod dimer obeys the exponential size dependence
according to the Universal Plasmon Ruler Equation. However, it was shown
recently that such a model does not hold at short nanorod distance (Nano Lett.
2009, 9, 1651). Here we study the nanorod coupling in various cases, including
nanorod dimer with the asymmetrical lengths and symmetrical dimer with the
varying gap width. The asymmetrical nanorod dimer causes two plasmon modes: one
is the attractive lower- energy mode and the other the repulsive high-energy
mode. Using a simple coupled LC-resonator model, the position of dimer
resonance has been determined analytically. Moreover, we found that the plasmon
coupling of symmetrical cylindrical (or rectangular) nanorod dimer is governed
uniquely by gap width scaled for the (effective) rod radius rather than for the
rod length. A new Plasmon Ruler Equation without using the fitting parameters
has been proposed, which agrees well with the FDTD calculations. The method has
also been extended to study the plasmonic wave-guiding in a linear chain of
gold nanorod particles. A field decay length up to 2700nm with the lateral mode
size about 50nm (~wavelength/28) has been suggested.Comment: 31 pages, 6 figures, 58 reference
A functional variant in the Stearoyl-CoA desaturase gene promoter enhances fatty acid desaturation in pork
There is growing public concern about reducing saturated fat intake. Stearoyl-CoA desaturase (SCD) is the lipogenic enzyme responsible for the biosynthesis of oleic acid (18:1) by desaturating stearic acid (18:0). Here we describe a total of 18 mutations in the promoter and 3′ non-coding region of the pig SCD gene and provide evidence that allele T at AY487830:g.2228T>C in the promoter region enhances fat desaturation (the ratio 18:1/18:0 in muscle increases from 3.78 to 4.43 in opposite homozygotes) without affecting fat content (18:0+18:1, intramuscular fat content, and backfat thickness). No mutations that could affect the functionality of the protein were found in the coding region. First, we proved in a purebred Duroc line that the C-T-A haplotype of the 3 single nucleotide polymorphisms (SNPs) (g.2108C>T; g.2228T>C; g.2281A>G) of the promoter region was additively associated to enhanced 18:1/18:0 both in muscle and subcutaneous fat, but not in liver. We show that this association was consistent over a 10-year period of overlapping generations and, in line with these results, that the C-T-A haplotype displayed greater SCD mRNA expression in muscle. The effect of this haplotype was validated both internally, by comparing opposite homozygote siblings, and externally, by using experimental Duroc-based crossbreds. Second, the g.2281A>G and the g.2108C>T SNPs were excluded as causative mutations using new and previously published data, restricting the causality to g.2228T>C SNP, the last source of genetic variation within the haplotype. This mutation is positioned in the core sequence of several putative transcription factor binding sites, so that there are several plausible mechanisms by which allele T enhances 18:1/18:0 and, consequently, the proportion of monounsaturated to saturated fat.This research was supported by grants from the Spanish Ministry of Science and Innovation (AGL2009-09779 and AGL2012-33529). RRF is recipient of a PhD scholarship from the Spanish Ministry of Science and Innovation (BES-2010-034607). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of manuscript
Modifying magnetic dipole spontaneous emission with nanophotonic structures
Tailoring of electromagnetic spontaneous emission predicted by E. M. Purcell more than 50 years ago has undoubtedly proven to be one of the most important effects in the rich areas of quantum optics and nanophotonics. Although during the past decades the research in this field has been focused on electric dipole emission, the recent progress in nanofabrication and study of magnetic quantum emitters, such as rare-earth ions, has stimulated the investigation of the magnetic side of spontaneous emission. Here, we review the state-of-the-art advances in the field of spontaneous emission enhancement of magnetic dipole quantum emitters with the use of various nanophotonics systems. We provide the general theory describing the Purcell effect of magnetic emitters, overview realizations of specific nanophotonics structures allowing for the enhanced magnetic dipole spontaneous emission, and give an outlook on the challenges in this field, which remain open to future research
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