Robustness of the far-field response of nonlocal plasmonic ensembles

Contrary to classical predictions, the optical response of few-nm plasmonic particles depends on particle size due to effects such as nonlocality and electron spill-out. Ensembles of such nanoparticles (NPs) are therefore expected to exhibit a nonclassical inhomogeneous spectral broadening due to size distribution. For a normal distribution of free-electron NPs, and within the simple nonlocal Hydrodynamic Drude Model (HDM), both the nonlocal blueshift and the plasmon linewidth are shown to be considerably affected by ensemble averaging. Size-variance effects tend however to conceal nonlocality to a lesser extent when the homogeneous size-dependent broadening of individual NPs is taken into account, either through a local size-dependent damping (SDD) model or through the Generalized Nonlocal Optical Response (GNOR) theory. The role of ensemble averaging is further explored in realistic distributions of noble-metal NPs, as encountered in experiments, while an analytical expression to evaluate the importance of inhomogeneous broadening through measurable quantities is developed. Our findings are independent of the specific nonclassical theory used, thus providing important insight into a large range of experiments on nanoscale and quantum plasmonics

Confronting the Demise of a Mother Tongue: The Feasibility of Implementing Language Immersion Programs to Reinvigorate the Taiwanese Language

In Taiwan, where Mandarin is the official language, the survival of Taiwanese, the mother tongue of sixty percent of the island’s inhabitants, is threatened. In this article, the authors discuss data from previous and ongoing research on the role of language and the significance of language loss in the quest for a “Taiwanese identity.” Research shows that the dominance of Mandarin over Taiwanese plus the growing support for English in Taiwan are likely indications that current Mandarin/Taiwanese bilingualism is being replaced by Mandarin/English bilingualism. Canadian, Finnish, Basque and Catalonian models of language immersion programs will be proposed as an alternative to Taiwan’s current language policy. The authors argue that such models, when applied to a significant degree in Taiwan’s primary education system, will contribute to strengthening Taiwanese identity, to defending the right of youngsters to receive their education in their Taiwanese mother tongue, and to creating more effective English language training.Le mandarin, langue officielle de Taiwan, menace la survie du taiwanais, qui est la langue maternelle de soixante pour cent de la population de l’île. Dans le présent article, les auteurs discutent des résultats de leurs recherches précédentes et en cours et montrent la signifiance de la perte de la langue maternelle pour l’identité taiwanaise. Ils montrent également que la suprématie du mandarin sur le taiwanais et l’appui croissant en faveur de l’anglais à Taiwan laissent prévoir l’implantation d’un bilinguisme mandarin/anglais au détriment du bilinguisme mandarin/taiwanais. Les auteurs considèrent que les modèles d’enseignement bilingue immersif mis en place au Canada, en Finlande, dans le pays Basque et en Catalogne, s’ils étaient mis en oeuvre de façon généralisée à Taiwan, pourraient contribuer à renforcer l’identité taiwanaise, à défendre le droit des jeunes à une éducation dans leur langue maternelle et à favoriser l’enseignement plus efficace de l’anglais

Probing AGN Inner Structure with X-ray Obscured Type 1 AGN

Using the X-ray-selected active galactic nuclei (AGN) from the XMM-XXL north survey and the SDSS Baryon Oscillation Spectroscopic Survey (BOSS) spectroscopic follow-up of them, we compare the properties of X-ray unobscured and obscured broad-line AGN (BLAGN1 and BLAGN2; $N_\textrm{H}$below and above $10^{21.5}$ cm$^{-2}$), including their X-ray luminosity $L_X$, black hole mass, Eddington ratio $\lambda_{\textrm{Edd}}$, optical continuum and line features. We find that BLAGN2 have systematically larger broad line widths and hence apparently higher (lower) $M_{\textrm{BH}}$ ($\lambda_{\textrm{Edd}}$) than BLAGN1. We also find that the X-ray obscuration in BLAGN tends to coincide with optical dust extinction, which is optically thinner than that in narrow-line AGN (NLAGN) and likely partial-covering to the broad line region. All the results can be explained in the framework of a multi-component, clumpy torus model by interpreting BLAGN2 as an intermediate type between BLAGN1 and NLAGN in terms of an intermediate inclination angle.Comment: 21 pages, 12 figures, published in MNRA

Effect of Nanopowder Addition on the Sintering of Water-Atomized Iron Powder

A promising method of improving the densification of powder metallurgical steel components is to blend nanopowder with the otherwise typically used micrometre-sized powder. The higher surface-to-volume ratio of nanopowder is hypothesized to accelerate the sintering process and increase the inter-particle contact area between the powder particles. This is supposed to enhance the material transport and improve the densification. In the present investigation, water-atomized iron powder (−\ua045 μm) was mixed separately with pure iron and low-carbon steel nanopowder, each at a ratio of 95 to 5 pct. These powder mixes were compacted at different pressures (400, 600 and 800 MPa) and then sintered at 1350 \ub0C in a pure hydrogen atmosphere. The sintering behavior of the powder blend compacts was compared to that of the compact with micrometre-sized powder only. Densification commenced at much lower temperatures in the presence of nanopowder. To understand this, sintering at intermittent temperatures such as 500 \ub0C and 700 \ub0C was conducted. The fracture surface revealed that the nanopowder was sintered at between 500 \ub0C and 700 \ub0C, which in turn contributed to the densification of the powder mix at the lower temperature range. Based on the sintering experiments, an attempt was made to calculate the activation energy and identify the associated sinter mechanism using two different approaches. It was shown that the first approach yielded values in agreement with the grain-boundary diffusion mechanism. As the nanopowder content increased, there was an increase in linear shrinkage during sintering

Reduction of thermal resistance of Ag-coated GFs/copper structure using nano-Ag paste as interconnection

Reduction of the thermal resistance between graphene films (GFs) and substrate is crucial to the application of GFs in thermal management. GFs/copper structures were prepared using nano-Ag paste as interconnection material. The effect of the thickness of nano-Ag paste on thermal resistance of GFs/copper structure was investigated. A thin layer of Ag was coated on GFs by physical vapor deposition (PVD) to further reduce thermal resistance. The thermal resistance of GFs/copper structure using Ag-coated GFs is 5.84% lower than that using raw GFs. The thermal resistance of GFs/copper structure decreases first and then increases with the increase of coating temperature and thickness of Ag layer. The minimum thermal resistance of 1.64 mm2\ub7K\ub7W-1 was gained for GFs/copper structure using GFs coated Ag at 300 ℃ for 60 min