Developing a nanoscale, integrable, and electrically pumped single mode light source is an essential step toward on-chip optical information technologies and sensors. Here, we demonstrate nanocavity ...enhanced electroluminescence in van der Waals heterostructures (vdWhs) at room temperature. The vertically assembled light-emitting device uses graphene/boron nitride as top and bottom tunneling contacts and monolayer WSe2 as an active light emitter. By integrating a photonic crystal cavity on top of the vdWh, we observe the electroluminescence is locally enhanced (>4 times) by the nanocavity. The emission at the cavity resonance is single mode and highly linearly polarized (84%) along the cavity mode. By applying voltage pulses, we demonstrate direct modulation of this single mode electroluminescence at a speed of ∼1 MHz, which is faster than most of the planar optoelectronics based on transition metal chalcogenides (TMDCs). Our work shows that cavity integrated vdWhs present a promising nanoscale optoelectronic platform.
The adaptive learning problem concerns how to create an individualized learning plan (also referred to as a learning policy) that chooses the most appropriate learning materials based on a learner’s ...latent traits. In this article, we study an important yet less-addressed adaptive learning problem—one that assumes continuous latent traits. Specifically, we formulate the adaptive learning problem as a Markov decision process. We assume latent traits to be continuous with an unknown transition model and apply a model-free deep reinforcement learning algorithm—the deep Q-learning algorithm—that can effectively find the optimal learning policy from data on learners’ learning process without knowing the actual transition model of the learners’ continuous latent traits. To efficiently utilize available data, we also develop a transition model estimator that emulates the learner’s learning process using neural networks. The transition model estimator can be used in the deep Q-learning algorithm so that it can more efficiently discover the optimal learning policy for a learner. Numerical simulation studies verify that the proposed algorithm is very efficient in finding a good learning policy. Especially with the aid of a transition model estimator, it can find the optimal learning policy after training using a small number of learners.
Chronic treatment with second-generation antipsychotic drugs (SGAs) has been associated with an increased risk of metabolic syndrome. To evaluate the longitudinal changes in glucose-lipid homeostasis ...after SGA use, we studied the time-dependent effects of olanzapine (OLZ) (3 mg/kg, b.i.d.) or clozapine (CLZ) (20 mg/kg, b.i.d.) treatment on metabolic profiles for 9 weeks in rats. Although only OLZ significantly increased body weight in rats, both OLZ and CLZ elevated blood lipid levels. Chronic OLZ treatment induced significant weight gain leading to a higher fasting insulin level and impaired glucose tolerance, whereas CLZ lowered fasting insulin levels and impaired glucose tolerance independent of weight gain. Treatment with both drugs deranged AKT/GSK phosphorylation and up-regulated muscarinic M3 receptors in the rats' livers. Consistent with an elevation in lipid levels, both OLZ and CLZ significantly increased the protein levels of nuclear sterol regulatory element-binding proteins (SREBPs) in the liver, which was associated with improvement in hepatic histamine H1R. However, enhanced carbohydrate response element binding protein (ChREBP) signalling was observed in only CLZ-treated rats. These results suggest that SGA-induced glucose-lipid metabolic disturbances could be independent of weight gain, possibly through activation of SREBP/ChREBP in the liver.
Unsymmetrical disulfides have been effectively prepared through thiol exchange with symmetrical disulfides employing a simple PdCl2/DMSO catalytic system. The given method features excellent ...functional group tolerance, a broad substrate scope, and operational simplicity. This reaction is especially useful for late-stage functionalization of bioactive scaffolds such as peptides and pharmaceuticals. Disulfide-containing organic dyes have also been prepared. This transformation could be extended to thiol–diselenide or thiol–ditelluride exchange affording RS–SeR′ or RS–TeR′.
In order to investigate and predict the quality of hepatopancreas of Eriocheir sinensis during frozen storage, fatty acid content, peroxide value (POV), acid value (AV) and anisidine value (AnV) were ...determined at −20, −40 and −80 °C, respectively. According to the investigative results, lipid oxidation indexes at −20 °C was higher than at −40 and −80 °C, and the degree of lipid oxidation was the least at −80 °C. In the meantime, the back propagation neural network with 10 neurons was developed to predict lipid stability of the samples during frozen storage with low MSE (0.00023) and high R2 (0.999). Besides, the changes to nutritional quality were evaluated using the index of atherogenesis (AI) and the index of thrombosis (TI). Furthermore, tri-step spectroscopy was applied to analyze and characterize the degree of lipid oxidation. The profile of characteristic peak was spatially revealed by the stereomicroscopy with group-peak at 2924 cm−1, 2854 cm−1, 1745 cm−1, 1641 cm−1, 1461 cm−1 and 1158 cm−1 and were unveiled by the second derivative infrared spectroscopy (SD-IR) for higher resolution, the samples stored at different temperatures were further identified through two-dimensional correlation infrared spectroscopy (2DCOS-IR).
•Lipid stability of hepatopancreas of Eriocheir sinensis was evaluated systematically.•BPNN were utilized first in frozen hepatopancreas of Eriocheir sinensis.•BPNN could accurately predict lipid oxidation indexs throughout the whole period.•Fatty acid profile changed progressively during frozen storage.•Tri-step IR spectroscopy was an effective method to characterize the lipid oxidation.
•Eriocheir sinensis, an euryhaline crustacean, is a specialty freshwater product.•Tri-step IR spectroscopy was an effective method to identify the taste components.•The contents of main ...salinity-responsive contributors were determined.•The optimal period of temporary rearing in the brackish water was about 4 weeks.
We investigated the effect of temporary rearing in brackish water on the taste quality in meat of crab cooked. The main salinity-responsive factors included 5ʹ-nucleotides and free amino acids (FAAs) in crab meat that were identified using tri-step infrared spectroscopy. Compared to the fresh water group, the contents of 5ʹ-adenosine monophosphate and 5ʹ-inosine monophosphate in the brackish water group significantly increased in the 2nd week and decreased in the 6th week, respectively. The contribution ratio of umami FAAs increased from 8.1 to 13.5% in the 4th week in the brackish water group, showing maximum value of equivalent umami concentration. Moreover, Ca2+ and Cl− contents significantly increased in the 4th and 6th weeks, respectively (P < 0.05). Infrared spectroscopy was an effective method to identify the taste components. With respect to the taste quality, four weeks were determined as the best period for temporary rearing of the crab in brackish water.
We examined the impact of statins on Yes-associated Protein (YAP) localization, phosphorylation and transcriptional activity in human and mouse pancreatic ductal adenocarcinoma (PDAC) cells. Exposure ...of sparse cultures of PANC-1 and MiaPaCa-2 cells to cerivastatin or simvastatin induced a striking re-localization of YAP from the nucleus to the cytoplasm and inhibited the expression of the YAP/TEAD-regulated genes Connective Tissue Growth Factor (CTGF) and Cysteine-rich angiogenic inducer 61 (CYR61). Statins also prevented YAP nuclear import and expression of CTGF and CYR61 stimulated by the mitogenic combination of insulin and neurotensin in dense culture of these PDAC cells. Cerivastatin, simvastatin, atorvastatin and fluvastatin also inhibited colony formation by PANC-1 and MiaPaCa-2 cells in a dose-dependent manner. In contrast, the hydrophilic statin pravastatin did not exert any inhibitory effect even at a high concentration (10 μM). Mechanistically, cerivastatin did not alter the phosphorylation of YAP at Ser127 in either PANC-1 or MiaPaCa-2 cells incubated without or with neurotensin and insulin but blunted the assembly of actin stress fiber in these cells. We extended these findings with human PDAC cells using primary KC and KPC cells, (expressing KrasG12D or both KrasG12D and mutant p53, respectively) isolated from KC or KPC mice. Using cultures of these murine cells, we show that lipophilic statins induced striking YAP translocation from the nucleus to the cytoplasm, inhibited the expression of Ctgf, Cyr61 and Birc5 and profoundly inhibited colony formation of these cells. Administration of simvastatin to KC mice subjected to diet-induced obesity prevented early pancreatic acini depletion and PanIN formation. Collectively, our results show that lipophilic statins restrain YAP activity and proliferation in pancreatic cancer cell models in vitro and attenuates early lesions leading to PDAC in vivo.
Ultrathin and flat optical lenses are essential for modern optical imaging, spectroscopy, and energy harvesting. Dielectric metasurfaces comprising nanoscale quasi-periodic resonator arrays are ...promising for such applications, as they can tailor the phase, amplitude, and polarization of light at subwavelength resolution, enabling multifunctional optical elements. To achieve 2π phase coverage, however, most dielectric metalenses need a thickness comparable to the wavelength, requiring the fabrication of high-aspect-ratio scattering elements. We report ultrathin dielectric metalenses made of van der Waals (vdW) materials, leveraging their high refractive indices and the incomplete phase design approach to achieve device thicknesses down to ∼λ/10, operating at infrared and visible wavelengths. These materials have generated strong interest in recent years due to their advantageous optoelectronic properties. Using vdW metalenses, we demonstrate near-diffraction-limited focusing and imaging and exploit their layered nature to transfer the fabricated metalenses onto flexible substrates to show strain-induced tunable focusing. Our work enables further downscaling of optical elements and opportunities for the integration of metasurface optics in ultraminiature optoelectronic systems.
The development of new and efficient methodology for the construction of optically active molecules is of great interest in both synthetic organic and medicinal chemistry fields. To this end, the ...personal account summarizes our studies on the development of electron‐deficient alkenes, allenes, and alkynes containing single activator as new dipolarophiles for Pd‐catalyzed asymmetric cycloaddition reactions. These new dipolarophiles can participate in Pd‐catalyzed asymmetric 3+2 and 4+2 cycloadditions through Pd‐π‐allyl 1,3‐ and 1,4‐zwitterions in‐situ generated by the reaction of Pd(0) catalyst with vinyl aziridines, vinyl epoxides, vinyl cyclopropanes, 4‐vinyl‐1,3‐dioxan‐2‐ones, and vinyl benzoxazinanones. These 3+2 and 4+2 cycloadditions provide efficient approaches to a wide range of enantiomerically enriched five‐ and six‐membered ring compounds containing contiguous chiral centers with high to excellent chemo‐, diastereo‐, and enantioselectivities. The utilities of these protocols are demonstrated by transformation of the cycloadducts into other useful chiral building blocks. DFT calculations reveal the dissimilar reactivity of different electron deficient alkenes and rationalize the mechanism and stereo‐control of the reaction. A Pd‐catalyzed inverse 3+2 cycloaddition is disclosed.
The development of new and efficient methodology for the construction of optically active molecules is of great interest in both synthetic organic and medicinal chemistry fields. This personal account summarizes our studies on the development of electron‐deficient alkenes, allenes, and alkynes containing single activator as new dipolarophiles for Pd‐catalyzed asymmetric cycloaddition reactions.
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