A simple and versatile in situ fabrication of MAPbX3 nanocrystal‐embedded polymer composite films is developed by controlling the crystallization process from precursor solutions. The composite films ...exhibit enhanced photoluminescence properties, improved stability, and excellent piezoelectric and mechanical properties. Applications of these composite films as color converters in liquid‐crystal‐display backlights are demonstrated, showing bright potential in display technology.
Described for the first time is that carbon dioxide (CO2) can be successfully inserted into aryl C−H bonds of the backbone of a metal–organic framework (MOF) to generate free carboxylate groups, ...which serve as Brønsted acid sites for efficiently catalyzing the methanolysis of epoxides. The work delineates the very first example of utilizing CO2 for heterogeneous C−H activation and carboxylation reactions on MOFs, and opens a new avenue for CO2 chemical transformations under mild reaction conditions.
Framed: CO2 is utilized for heterogeneous C−H activation and carboxylation reactions on metal–organic frameworks (MOFs). The formed carboxylate groups serve as Brønsted acid sites and were shown to efficiently catalyze the methanolysis of epoxides. This work introduces a new avenue for CO2 chemical transformations under mild reaction conditions.
The molecular components of the postsynaptic density (PSD) in excitatory synapses of the brain are currently being investigated as one of the major etiologies of neurodevelopmental disorders such as ...schizophrenia (SCZ) and autism. Postsynaptic density protein-95 (PSD-95) is a major regulator of synaptic maturation by interacting, stabilizing and trafficking N-methyl-d-aspartic acid receptors (NMDARs) and α-amino-3-hydroxy-5-methyl-4-isox-azoleproprionic acid receptors (AMPARs) to the postsynaptic membrane. Recently, there has been overwhelming evidence that associates PSD-95 disruption with cognitive and learning deficits observed in SCZ and autism. For instance, recent genomic and sequencing studies of psychiatric patients highlight the aberrations at the PSD of glutamatergic synapses that include PSD-95 dysfunction. In animal studies, PSD-95 deficiency shows alterations in NMDA and AMPA-receptor composition and function in specific brain regions that may contribute to phenotypes observed in neuropsychiatric pathologies. In this review, we describe the role of PSD-95 as an essential scaffolding protein during synaptogenesis and neurodevelopment. More specifically, we discuss its interactions with NMDA receptor subunits that potentially affect glutamate transmission, and the formation of silent synapses during critical time points of neurodevelopment. Furthermore, we describe how PSD-95 may alter dendritic spine morphologies, thus regulating synaptic function that influences behavioral phenotypes in SCZ versus autism. Understanding the role of PSD-95 in the neuropathologies of SCZ and autism will give an insight of the cellular and molecular attributes in the disorders, thus providing treatment options in patients affected.
•PSD-95 mediates NMDA and AMPA receptor clustering and function.•Genetic implications of PSD-95 deficiency in schizophrenia•PSD-95 & NMDAR dysregulation in schizophrenia•PSD-95 regulates spine density involved in schizophrenia.•PSD-95 is associated with NMDAR dysregulation and spine change in autism.
Oxygen evolution reaction (OER) is a pivotal reaction in many technologies for renewable energy, such as water splitting, metal–air batteries, and regenerative fuel cells. However, this reaction is ...known to be kinetically sluggish and proceeds at rather high overpotential due to the universal scaling relationship, namely, the adsorption energies of intermediates are linearly correlated and cannot be optimized simultaneously. Several approaches have been proposed to break the scaling relationship by introducing additional active sites; however, positive experimental results are still absent. Herein, a different solution is suggested on the basis of dynamic tridimensional adsorption of the OER intermediates at NiO/NiFe layered double hydroxide intersection, by which the adsorption energy of each intermediate can be adjusted independently, so as to bypass the scaling relationship and achieve high catalytic performance. Experimentally, the OER overpotential is reduced to ≈205 mV at current density of 30 mA cm−2, which represents the best performance achieved by state‐of‐the‐art OER catalysts.
The oxygen evolution reaction (OER), a key reaction for energy conversion and storage, is kinetically sluggish due to the limits of the scaling relationship. A strategy to bypass the scaling relationship through dynamic tridimensional adsorption of OER intermediates is reported, and OER overpotential is reduced to 205 mV at current density of 30 mA cm−2.
Elucidating the prefrontal cortical microcircuit has been challenging, given its role in multiple complex behaviors, including working memory, cognitive flexibility, attention, social interaction and ...emotional regulation. Additionally, previous methodological limitations made it difficult to parse out the contribution of certain neuronal subpopulations in refining cortical representations. However, growing evidence supports a fundamental role of fast-spiking parvalbumin (PV) GABAergic interneurons in regulating pyramidal neuron activity to drive appropriate behavioral responses. Further, their function is heavily diminished in the prefrontal cortex (PFC) in numerous psychiatric diseases, including schizophrenia and autism. Previous research has demonstrated the importance of the optimal balance of excitation and inhibition (E/I) in cortical circuits in maintaining the efficiency of cortical information processing. Although we are still unraveling the mechanisms of information representation in the PFC, the E/I balance seems to be crucial, as pharmacological, chemogenetic and optogenetic approaches for disrupting E/I balance induce impairments in a range of PFC-dependent behaviors. In this review, we will explore two key hypotheses. First, PV interneurons are powerful regulators of E/I balance in the PFC, and help optimize the representation and processing of supramodal information in PFC. Second, diminishing the function of PV interneurons is sufficient to generate an elaborate symptom sequelae corresponding to those observed in a range of psychiatric diseases. Then, using this framework, we will speculate on whether this circuitry could represent a platform for the development of therapeutic interventions in disorders of PFC function.
Orthogonal time frequency space (OTFS) modulation has superior performance than traditional orthogonal frequency division multiplexing (OFDM) in fast time-varying scenarios. However, due to the ...effect of Doppler shift, higher pilot overhead and pilot power are required to estimate the channel state information. According to the sparseness of the channel in the delay-Doppler domain, this letter proposes a new pilot pattern and a sparse Bayesian learning (SBL)-based channel estimation algorithm. There is no guard pilot in the pilot pattern, and the pilot has the same power as the data. Based on the new pilot pattern, we first convert the channel estimation problem to a sparse signal recovery problem. Then, we introduce a sparse Bayesian learning framework and construct a sparse signal prior model as a hierarchical Laplace prior. Finally, the expected maximum (EM) algorithm is used to update the parameters in the prior model. Numerical simulation highlights the superiority of the proposed algorithm in terms of pilot overhead, pilot power consumption, and anti-noise interference.
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•A focus on the recent developments of supramolecular catalysis based on HCCs.•Metalloligand and self-sorting approaches are commonly used to construct HCCs.•Instances of catalytic ...macrocyclic or cage-like HCCs are discussed in detail.
The rational design and facile construction of discrete heterometallic supramolecular catalysts have precipitated a surge of research interest in emulating sophisticated natural catalysts with well-defined cavities and inlaid active sites, allowing conversion of encapsulated substrates with high chemo-, regio-, and stereoselectivity. This review briefly highlights such discrete, heterometallic, coordination-driven metallacycles and metallacages obtained by the strategic utilization of a range of predesigned building blocks in the supramolecular chemist’s toolkit. The two major synthetic strategies toward these metalla-architectures are presented, and special attention has been paid to discussing both the fascinating structures and the unique catalytic performance of various heterometallic macrocycles and cages.
Waveplates are widely used in photonics to control the polarization of light1,2. Often, they are fabricated from birefringent crystals that have different refractive indices along and normal to the ...crystal axis. Similar optical components are found in the natural world, including the eyes of mantis shrimp3,4 and the iridescence of giant clams5, fish6 and plants7. Optical retardation in biology relies on sophisticated self-assembly, whereas man-made systems comprise multiple-layered materials8–11. Here we report a discovery that bridges these two design principles. We observe wideband achromatic retardation in the visible and near-infrared (532–800 nm) regions for Cs4PbBr6 perovskite crystals embedded with CsPbBr3 nanocrystals. We explain our observations as matched dispersions of the refractive indices of the ordinary and extraordinary rays caused by the ordered embedding of the nanocrystals in the host. The wideband performance and ease of fabrication of these perovskite materials are attractive for future applications.Perovskite crystals of Cs4PbBr6 embedded with CsPbBr3 nanocrystals are shown to act as wideband, achromatic waveplates in the visible and near-infrared regions.
Traditional patch-based sparse representation modeling of natural images usually suffer from two problems. First, it has to solve a large-scale optimization problem with high computational complexity ...in dictionary learning. Second, each patch is considered independently in dictionary learning and sparse coding, which ignores the relationship among patches, resulting in inaccurate sparse coding coefficients. In this paper, instead of using patch as the basic unit of sparse representation, we exploit the concept of group as the basic unit of sparse representation, which is composed of nonlocal patches with similar structures, and establish a novel sparse representation modeling of natural images, called group-based sparse representation (GSR). The proposed GSR is able to sparsely represent natural images in the domain of group, which enforces the intrinsic local sparsity and nonlocal self-similarity of images simultaneously in a unified framework. In addition, an effective self-adaptive dictionary learning method for each group with low complexity is designed, rather than dictionary learning from natural images. To make GSR tractable and robust, a split Bregman-based technique is developed to solve the proposed GSR-driven ℓ 0 minimization problem for image restoration efficiently. Extensive experiments on image inpainting, image deblurring and image compressive sensing recovery manifest that the proposed GSR modeling outperforms many current state-of-the-art schemes in both peak signal-to-noise ratio and visual perception.
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