Ultra-low-loss CMOS-Compatible Waveguide Crossing Arrays Based on Multimode Bloch Waves and Imaginary Coupling

We experimentally demonstrate broadband waveguide crossing arrays showing ultra low loss down to $0.04\,$dB/crossing ($0.9\%$), matching theory, and crosstalk suppression over $35\,$dB, in a CMOS-compatible geometry. The principle of operation is the tailored excitation of a low-loss spatial Bloch wave formed by matching the periodicity of the crossing array to the difference in propagation constants of the 1$^\text{st}$- and 3$^\text{rd}$-order TE-like modes of a multimode silicon waveguide. Radiative scattering at the crossing points acts like a periodic imaginary-permittivity perturbation that couples two supermodes, which results in imaginary (radiative) propagation-constant splitting and gives rise to a low-loss, unidirectional breathing Bloch wave. This type of crossing array provides a robust implementation of a key component enabling dense photonic integration

Defatted Biomass of the Microalga, Desmodesmus sp., Can Replace Fishmeal in the Feeds for Atlantic salmon

Microalgal biomass is a potential feed ingredient that can replace fishmeal and ensure sustainability standards in aquaculture. To understand the efficacy of the defatted biomass from the marine microalga, Desmodesmus sp. a 70-day feeding study was performed with Atlantic salmon (Salmo salar) smolts. Three groups of fish (av. wt. 167 g) were offered either a control feed (without the microalga) or the microalga-containing (10/20%) feeds. At the end of the feeding period, the growth indices (condition factor, specific growth rate) and survival of the microalga-fed fish were not significantly different from the respective values of the control fish, but the feed conversion ratios were inferior. The proximate composition of the whole body of salmon from the three groups did not vary significantly. Compared to the control fish, the alga-fed fish had lower lipid content (10% alga-fed fish) in their fillet. The protein and lipid digestibility in the three feeds did not differ significantly, but the digestibility of energy in the 10% alga-feed was significantly lower than that of the control feed. Furthermore, comparison of the distal intestinal proteome of Atlantic salmon revealed that the expressions of Alpha-2-HS-glycoprotein-like (Ahsg), Myosin-11 isoform X1 (My11) and Dihydrolipoyl dehydrogenase, mitochondrial-like (Dld) were altered by the microalgal feeding. Examination of the physiological status of the fish based on the serum antioxidant capacities did not reveal any alga-feed-related differences. Moreover, the expression of the selected immune and inflammatory marker genes and the micromorphological observations did not indicate any aberration in the intestinal health of the microalga-fed fish. It is possible to include 20% of defatted Desmodesmus sp. in the feeds of Atlantic salmon

The antecedents and consequences of value co-creation behaviors in a hotel setting: a two-country study

This study examines the antecedents and consequences of value co-creation behavior in a hospitality context. An online questionnaire with samples of hotel patrons in the United States and Australia was used to obtain data and partial least square modeling was used in the analysis. The results suggest patron fairness perception enhances trust and identification with a hotel, which encourage engagement in the value co-creation behavior. Furthermore, this behavior enhances patron well-being and respect for the hotel. The study contributes to the literature by suggesting a value co-creation behavior model in the hospitality context and empirically examining the antecedents and consequences of this behavior. The results have important implications for managers designing service encounters that can encourage hotel patrons to engage in the value co-creation behavior

Electric Field Effect in Multilayer Cr2Ge2Te6: a Ferromagnetic Two-Dimensional Material

The emergence of two-dimensional (2D) materials has attracted a great deal of attention due to their fascinating physical properties and potential applications for future nanoelectronic devices. Since the first isolation of graphene, a Dirac material, a large family of new functional 2D materials have been discovered and characterized, including insulating 2D boron nitride, semiconducting 2D transition metal dichalcogenides and black phosphorus, and superconducting 2D bismuth strontium calcium copper oxide, molybdenum disulphide and niobium selenide, etc. Here, we report the identification of ferromagnetic thin flakes of Cr2Ge2Te6 (CGT) with thickness down to a few nanometers, which provides a very important piece to the van der Waals structures consisting of various 2D materials. We further demonstrate the giant modulation of the channel resistance of 2D CGT devices via electric field effect. Our results illustrate the gate voltage tunability of 2D CGT and the potential of CGT, a ferromagnetic 2D material, as a new functional quantum material for applications in future nanoelectronics and spintronics.Comment: To appear in 2D Material

Mechanism of Iron-Catalyzed Oxidative α-Amination of Ketones with Sulfonamides

We report the mechanism of the iron-catalyzed oxidative α-amination of ketones with sulfonamides. Using linear free energy relationships, competition experiments, and identification of reaction intermediates, we have found that the mechanism of this reaction proceeds through rate-limiting electron transfer to 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) from an iron enolate in the process of forming an α-DDQ adduct. The adduct then serves as the electrophile for substitution with sulfonamide nucleophiles, accelerated by iron and additional DDQ. This mechanistic study rules out formation of an α-carbocation intermediate and purely radical mechanistic hypotheses

Temperature-Dependent Anomalies in the Structure of the (001) Surface of LiCu2O2

Surface corrugation functions, derived from elastic helium atom scattering (HAS) diffraction patterns at different temperatures, reveal that the Cu2+ rows in the (001) surface of LiCu2O2 undergo an outward displacement of about 0.15 {\AA} as the surface was cooled down to 140 K. This is probably the first time that isolated one-dimensional magnetic ion arrays were realized, which qualifies the Li1+Cu2+O2-2 surface as a candidate to study one-dimensional magnetism. The rising Cu2+ rows induce a surface incommensurate structural transition along the a-direction. Surface equilibrium analysis showed that the surface Cu2+ ions at bulk-like positions experience a net outward force along the surface normal which is relieved by the displacement. Temperature-dependent changes of the surface phonon dispersions obtained with the aid of inelastic HAS measurements combined with surface lattice dynamical calculations are also reported.Comment: 4 pages, 7 figure