The ability to record images with extreme temporal resolution enables a diverse range of applications, such as fluorescence lifetime imaging, time-of-flight depth imaging and characterization of ultrafast processes. Recently, ultrafast imaging schemes have emerged, which require either long acquisition times or raster scanning and have a requirement for sufficient signal that can only be achieved when light is reflected off an object or diffused by a strongly scattering medium. Here we present a demonstration of the potential of single-photon detector arrays for visualization and rapid characterization of events evolving on picosecond time scales. The single-photon sensitivity, temporal resolution and full-field imaging capability enables the observation of light-in-flight in air, as well as the measurement of laser-induced plasma formation and dynamics in its natural environment. The extreme sensitivity and short acquisition times pave the way for real-time imaging of ultrafast processes or visualization and tracking of objects hidden from view.

Whispering-gallery-mode resonators have been extensively used in conjunction with different materials for the development of a variety of photonic devices. Among the latter, hybrid structures, consisting of dielectric microspheres and colloidal core/shell semiconductor nanocrystals as gain media, have attracted interest for the development of microlasers and studies of cavity quantum electrodynamic effects. Here we demonstrate single-exciton, single-mode, spectrally tuned lasing from ensembles of optical antenna-designed, colloidal core/shell CdSe/CdS quantum rods deposited on silica microspheres. We obtain single-exciton emission by capitalizing on the band structure of the specific core/shell architecture that strongly localizes holes in the core, and the two-dimensional quantum confinement of electrons across the elongated shell. This creates a type-II conduction band alignment driven by coulombic repulsion that eliminates non-radiative multi-exciton Auger recombination processes, thereby inducing a large exciton–bi-exciton energy shift. Their ultra-low thresholds and single-mode, single-exciton emission make these hybrid lasers appealing for various applications, including quantum information processing.

Background/Aims: Our previous reports suggested that dietary supplementation with lysine influenced intestinal absorption and metabolism of amino acids. In this study, we further investigated the effect of lysine restriction (30%) on feed intake and we also tested the hypothesis that gut microbiome contributed to the potential mechanism of lysine restriction-mediated feeding behavior. Here, we profiled gut microbial communities by sequencing 16S ribosomal ribonucleic acid (rRNA) genes from gut samples as well as growth performance, serum hormones, and intestinal lysine transport in a piglet model. Results: Piglets preferred to the lysine restricted diet when giving three diets and the feed intake was markedly higher in the lysine-restricted group than that in the control group. Altered hormones (leptin, CCK, and ghrelin) might contribute to the feeding behavior caused by lysine restriction. Meanwhile, lysine transporting ability (SLC7A1 and SLC7A2 expression, intestinal electrophysiological changes, and amino acid pool in mesenteric vein) was decreased in response to lysine restriction. Through deep sequencing of bacterial rRNA markers, we observed that bacterial diversity was enhanced in the lysine-restricted group (Shannon H, PD, and Chao1). At the phylum level, lysine restriction enhanced gut Actinobacteria, Saccharibacteria, and Synergistetes abundances. At the family level, Moraxellaceae, Halomonadaceae, Shewanellaceae, Corynebacteriaceae, Bacillaceae, Comamonadaceae, Microbacteriaceae, Caulobacteraceae, and Synergistaceae abundances were increased in response to lysine restriction. Predictive functional profiling of microbial communities by PICRUSt also confirmed that dietary lysine restriction affected gut microbiome, which might further mediate amino acid metabolism, membrane transport, and endocrine system. Conclusion: Our results indicated that lysine restriction inhibited intestinal lysine transport and promoted feed intake, which might be associated with gut microbiome.

The molecular photophysics and thermally activated delayed fluorescence (TADF) in spiro compounds are distinct because of the rigid orthogonal C–C bridging bond between donor and acceptor. The photophysics is found to be highly complex, with unprecedented multiple anti-Kasha emissions from three different singlet states, two of which are one-photon forbidden. The TADF mechanism is critically controlled by local acceptor nπ* states; the singlet nπ* state undergoes rapid intersystem crossing populating an energetically close acceptor ππ* triplet state. The acceptor triplet nπ* state couples nonadiabatically to a CT triplet state mediating reverse intersystem crossing. When the nπ* and CT states are energetically close, TADF is greatly enhanced with rISC rate reaching 10 7 s –1 . We observe neither DF from the singlet nπ* state nor electron transfer (ET) to form the 1 CT because there is no ET driving force; however, ET from the higher-energy donor singlet ππ* state readily occurs along with donor emission.

Mental rotation is an important paradigm for spatial ability. Mental-rotation tasks are assumed to involve five or three sequential cognitive-processing states, though this has not been demonstrated experimentally. Here, we investigated how processing states alternate during mental-rotation tasks. Inference was carried out using an advanced statistical modelling and data-driven approach – a discriminative hidden Markov model (dHMM) trained using eye-movement data obtained from an experiment consisting of two different strategies: (I) mentally rotate the right-side figure to be aligned with the left-side figure and (II) mentally rotate the left-side figure to be aligned with the right-side figure. Eye movements were found to contain the necessary information for determining the processing strategy, and the dHMM that best fit our data segmented the mental-rotation process into three hidden states, which we termed encoding and searching, comparison, and searching on one-side pair. Additionally, we applied three classification methods, logistic regression, support vector model and dHMM, of which dHMM predicted the strategies with the highest accuracy (76.8%). Our study did confirm that there are differences in processing states between these two of mental-rotation strategies, and were consistent with the previous suggestion that mental rotation is discrete process that is accomplished in a piecemeal fashion.