Broadband Quantum Efficiency Enhancement in High Index Nanowires Resonators

Light trapping in sub-wavelength semiconductor nanowires (NWs) offers a promising approach to simultaneously reducing material consumption and enhancing photovoltaic performance. Nevertheless, the absorption efficiency of a NW, defined by the ratio of optical absorption cross section to the NW diameter, lingers around 1 in existing NW photonic devices, and the absorption enhancement suffers from a narrow spectral width. Here, we show that the absorption efficiency can be significantly improved in NWs with higher refractive indices, by an experimental observation of up to 350% external quantum efficiency (EQE) in lead sulfide (PbS) NW resonators, a 3-fold increase compared to Si NWs. Furthermore, broadband absorption enhancement is achieved in single tapered NWs, where light of various wavelengths is absorbed at segments with different diameters analogous to a tandem solar cell. Overall, the single NW Schottky junction solar cells benefit from optical resonance, near bandgap open circuit voltage, and long minority carrier diffusion length, demonstrating power conversion efficiency (PCE) comparable to single Si NW coaxial p-n junction cells11, but with much simpler fabrication processes

The genus Sialis Latreille, 1802 (Megaloptera: Sialidae) in Palaearctic China, with description of a new species

The species of the genus Sialis from Palaearctic China are revised. Three species are described, including Sialis henanensis sp. n. A key to the males of the species of Sialis from Palaearctic China is presented

Providing Informative Nutrition Facts for Food Ordering

Online food ordering services provide little to no information regarding nutritional facts. This makes it difficult for customers to make decisions based on their nutrition and health needs. This disclosure describes an online food ordering service that provides users the nutritional facts of a food item prior to order placement. The information is provided via a suitable user interface of a website or app that enables the user to drill down further to obtain more granular information. If the user permits, prior orders of the users are used to provide periodic feedback regarding eating behavior and nutritional intake

On-the-fly machine learning for parametrization of the effective Hamiltonian

The first-principles-based effective Hamiltonian is widely used to predict and simulate the properties of ferroelectrics and relaxor ferroelectrics. However, the parametrization method of the effective Hamiltonian is complicated and hardly can resolve the systems with complex interactions and/or complex components. Here, we developed an on-the-fly machine learning approach to parametrize the effective Hamiltonian based on Bayesian linear regression. The parametrization is completed in molecular dynamics simulations, with the energy, forces and stress predicted at each step along with their uncertainties. First-principles calculations are executed when the uncertainties are large to retrain the parameters. This approach provides a universal and automatic way to compute the effective Hamiltonian parameters for any considered systems including complex systems which previous methods can not handle. BaTiO3 and Pb(Sc,Ta)O3 are taken as examples to show the accurateness of this approach comparing with conventional first-principles parametrization method.Comment: 11 pages, 2 figure

A Study on the Practice of Folk Dance Culture in Kindergarten

China is characterized by a long history of development and a rich and colorful national culture. Folk dance culture shines in the field of excellent traditional culture. However, the progress of social development has led to the gradual extinction of folk dance. Preschool education, as the beginning stage of education in a person’s life, is a favorable time to embrace folk dance culture. By integrating folk dance into the stage of preschool education, it is conducive to carry forward the traditional culture of the nation and fostering national self-confidence and national pride in children while passing on the excellent traditional culture. Therefore, it is urgent to explore the path of combining folk dance culture with early childhood education

Negative electrocaloric effect in nonpolar phases of perovskite over wide range of temperature

The electrocaloric effect (ECE) offers a promising alternative to the traditional gas compressing refrigeration due to its high efficiency and environmental friendliness. The unusual negative electrocaloric effect refers to the adiabatic temperature drops due to application of electric field, in contrast with the normal (positive) ECE, and provides ways to improve the electrocaloric efficiency in refrigeration cycles. However, negative ECE is unusual and requires a clear understanding of microscopic mechanisms. Here, we found unexpected and extensive negative ECE in nonpolar orthorhombic, tetragonal, and cubic phases of halide and oxide perovskite at wide range of temperature by means of first-principle-based large scale Monte Carlo methods. Such unexpected negative ECE originates from the octahedral tilting related entropy change rather than the polarization entropy change under the application of electric field. Furthermore, a giant negative ECE with temperature change of 8.6 K is found at room temperature. This giant and extensive negative ECE in perovskite opens up new horizon in the research of caloric effects and broadens the electrocaloric refrigeration ways with high efficiency.Comment: 11 pages, 7 figure