We report on a magnetophotoluminescence study of single self-assembled semiconductor nanorings which are fabricated by molecular-beam epitaxy combined with AsBr 3 in situ etching. Oscillations in the neutral exciton radiative recombination energy and in the emission intensity are observed under an applied magnetic field. Further, we control the period of the oscillations with a gate potential that modifies the exciton confinement. We infer from the experimental results, combined with calculations, that the exciton Aharonov-Bohm effect may account for the observed effects.

This paper proposes a new electric load forecasting model by hybridizing the fuzzy time series (FTS) and global harmony search algorithm (GHSA) with least squares support vector machines (LSSVM), namely GHSA-FTS-LSSVM model. Firstly, the fuzzy c-means clustering (FCS) algorithm is used to calculate the clustering center of each cluster. Secondly, the LSSVM is applied to model the resultant series, which is optimized by GHSA. Finally, a real-world example is adopted to test the performance of the proposed model. In this investigation, the proposed model is verified using experimental datasets from the Guangdong Province Industrial Development Database, and results are compared against autoregressive integrated moving average (ARIMA) model and other algorithms hybridized with LSSVM including genetic algorithm (GA), particle swarm optimization (PSO), harmony search, and so on. The forecasting results indicate that the proposed GHSA-FTS-LSSVM model effectively generates more accurate predictive results.

With both spin and valley degrees of freedom, the low-lying excitonic spectra of photo-excited transition-metal dichalcogenide monolayers (TMDC-MLs) are featured by rich fine structures, comprising the intra-valley bright exciton states as well as various intra-and inter-valley dark ones. The latter states can be classified as those of the spin-and momentum-forbidden dark excitons according to the violated optical selection rules. Because of their optical invisibility, these two types of the dark states are in principle hardly observed and even distinguished in conventional spectroscopies although their impacts on the optical and dynamical properties of TMDC-MLs have 1 arXiv:1811.06728v3 [cond-mat.mes-hall] 9 Apr 2019 been well noticed. In this Letter, we present a theoretical and computational investigation of the exciton fine structures and the temperature-dependent photo-luminescence spectra of strained tungsten diselenide monolayers (WSe 2 -MLs) where the intra-valley spin-forbidden dark exciton lies in the lowest exciton states and other momentumforbidden states are in the higher energies that are tunable by external stress. The numerical computations are carried out by solving the Bethe-Salpeter equation for an exciton in a WSe 2 -ML under the stress-control in the tight-binding scheme established from the first principle computation in the density functional theory. According to the numerical computation and supportive model analysis, we reveal the distinctive signatures of the spin-and momentum-forbidden exciton states of strained WSe 2 -MLs in the temperature-dependent photo-luminescences and present the guiding principle to infer the relative energetic locations of the two types of dark excitons.

Resin adsorption and naringinase treatment represent two major methods for debittering naringin in citrus juices, but their effects on the aroma profiles of citrus juices have not been intensively investigated yet. In this study, the volatiles of the fresh, naringinase‐treated and resin‐absorbed juices of pummelo were investigated by gas chromatography coupled with a mass spectrometer (GC‐MS) and sensory evaluation. The fresh juice was analyzed to have 24 volatiles, among which (E)‐3‐hexen‐1‐ol and 1‐hexanol had the highest concentrations. After the naringinase treatment, the juice showed 32 volatiles, among which (Z)‐ and (E)‐linalool oxides were the most dominant in concentration; while the resin adsorption captured most of the volatiles. Principal component analysis (PCA) showed that naringinase treatment led to an increase in some compounds, particularly aldehydes, whereas resin adsorption decreased the amounts of a lot of volatile compounds. The sensory evaluation demonstrated the fresh and naringinase‐treated juices had similar aroma profiles, whereas the resin‐adsorbed juice had a much weaker aroma intensity than its counterparts. These results indicated that the naringinase treatment is more desirable than the resin adsorption for debittering citrus juice because the naringinase treatment could maintain the aroma profile close to the original, fresh juice. Copyright © 2015 John Wiley & Sons, Ltd.