Construction of a Long-Range Quantitative Fluorescence Sensor for Multiple Amine Vapors by π···π Aggregates of Carborane.

The exploitation of small molecules as fluorescence sensors represents a minimalistic solution toward the sensing of hazardous volatile organic compounds (VOCs). Compared with the conventional aggregation-induced emitting sensors, the carborane (Cb)-based sensors have exhibited multiple advantages and improved quantitative fluorescence (QF) sensing abilities toward the gaseous VOCs. However, in the current Cb-based sensors, the localization of a single responsive site toward VOCs remains less focused, which results in a bias in the trace detection and short-range testing windows.

Lattice Vacancy Induced Energy Renormalization of Photonic Quasiparticles in Two-Dimensional Semiconductors.

Coulomb interactions among dense charges and quasiparticle energy renormalization are at the center of quantum science because they significantly reshape the fundamental electronic and photonic properties of materials. While lattice vacancies are ubiquitous in solid materials, their physical effect on the Coulomb interaction among quasiparticles is normally weak and negligible. Here we show that in atomically thin semiconductors the presence of lattice vacancies emerges as an important but unexplored origin for the nontrivial renormalization of quasiparticle binding energies, due to the subtle modification of overall dielectric functions at low dimensionality.

Achieving Simplified and Tunable Flexibility in Carborane-Based Emitters for Quantitative Vapochromic VOC Sensing.

Photoluminescence (PL) sensing of volatile organic compounds (VOCs) represents a convenient and economic detection method toward air pollutants. However, tetraphenylethylene (TPE)-based and recent carborane (Cb)-based sensors retained multiple sites that are responsive to VOC stimulation, making quantitative PL sensing rather challenging. Rendering the simplified and tunable flexibility in the PL sensors is key to achieve the quantitative target.

All-Optical Switching Based on Sub-Bandgap Photoactivation of Charge Trapping in Metal Halide Perovskites.

Controllable optical properties are crucial for the application of light-emitting materials in optical devices. In this work, controllable photoluminescence in metal halide perovskite crystals is realized via photoactivation of their defects. It is found that under continuous excitation, the photoluminescence intensity of a CH NH PbBr crystal can be fully controlled by sub-bandgap energy photon illumination.

Moisture-Dependent Blinking of Individual CsPbBr Nanocrystals Revealed by Single-Particle Spectroscopy.

All-inorganic metal halide perovskite nanocrystals (NCs) have been exceptional candidates for high-performance solution-processed optoelectronic and photonic devices compared with organometal halide perovskite NCs due to their superior stability. However, the interactions between all-inorganic perovskite NCs and moisture, which is an acknowledged detrimental factor, are still under debate, and detailed investigations to uncover such fundamentals remain to be performed. Herein, with wide-field fluorescence microscopy, the burst photoluminescence blinking responses of CsPbBr NCs were observed in ambient air, and moisture rather than oxygen was verified to be the key factor that leads to the enhanced PL intensity and reduced OFF duration.

Ultrasensitive detection of local acoustic vibrations at room temperature by plasmon-enhanced single-molecule fluorescence.

Sensitive detection of local acoustic vibrations at the nanometer scale has promising potential applications involving miniaturized devices in many areas, such as geological exploration, military reconnaissance, and ultrasound imaging. However, sensitive detection of weak acoustic signals with high spatial resolution at room temperature has become a major challenge. Here, we report a nanometer-scale system for acoustic detection with a single molecule as a probe based on minute variations of its distance to the surface of a plasmonic gold nanorod.

Controllable Introduction of Surface Defects on CHNHPbI Perovskite.

One of the unique characteristics of semiconductors is the strong dependence of their properties on crystal defects and doping. However, due to the species diversity and low density, it is very difficult to control the type and concentration of the defects. In perovskite materials, crystal defects are randomly formed during the fast crystallization process, causing large heterogeneity of the samples.

Characterizing Academic Help-seeking Moods for Enrollment Performance of Institutional Online Student.

Few could have anticipated the sudden and dramatic impact of COVID-19 on all aspects of life, including online academic help-seeking of institutional education. Academic help-seeking is a quite prevalent phenomenon that supports students to learn knowledge and improve academic performance. This study is aiming to understand learners and associate their performances via exploiting academic help-seeking moods with online learning of institutional education setting.

Rational Building of Nonblinking Carbon Dots via Charged State Recovery.

Carbon dots (CDs), as emerging luminescent nanomaterials, possess excellent but complex properties, and thus, they have attracted immense attention for their applications. Further practical application of CDs has been hindered by their limited photostability and photoluminescence intermittency. In this study, we demonstrated that an antioxidant (Trolox) can dramatically enhance the photostability and minimize the photoblinking of CDs without affecting their native spectral characteristics.

Electric-Field-Induced Ion Migration Behavior in Methylammonium Lead Iodide Perovskite.

Ionic movement inside organometal halide perovskites (OMHP) materials has been widely reported to be linked with stability issues in the perovskite-based optoelectronic devices. However, the dynamic processes of the ionic movement and how they influence the devices are still not well-understood. In this work, we applied an external electric field to the CHNHPbI crystal and simultaneously monitored the PL behaviors.

Photostable and Uniform CHNHPbI Perovskite Film Prepared via Stoichiometric Modification and Solvent Engineering.

Solution-processed organometal halide perovskites (OMHPs) have been widely used in optoelectronic devices, and have exhibited brilliant performance. One of their generally recognized advantages is their easy fabrication procedure. However, such a procedure also brings uncertainty about the opto-electric properties of the final samples and devices, including morphology, stability, coverage ratio, and defect concentration.

Controlled Fluorescence Enhancement of DNA-Binding Dye Through Chain Length Match between Oligoguanine and TOTO.

Fluorescent DNA-binding dyes are extensively employed as probe and biosensing in biological detection and imaging. Experiments and theoretical calculations of thiazole orange homodimeric (TOTO) dye binding to a single-strand DNA (ssDNA), poly(dG) ( = 2, 4, 6, 8), reveal that the = 6 complex shows about 300-fold stronger fluorescence than = 2, 4 and a slightly stronger one than = 8 complexes, which is benefited from the length match between TOTO and poly(dG). The machine learning, based on molecular dynamics trajectories, indicates that TOTO is featured by the dihedral angle along its backbone and its end-to-end distance, in which the latter one defines the stretch and hairpin structures of TOTO, respectively.

Deactivation/Activation of Quenching Defects in CHNHPbI Perovskite by Direct Electron Injection/Extraction.

Organometal halide perovskites (OMHPs) have emerged as advisible materials for application in optoelectronic devices over the past decade. However, a variety of complex slow responses in OMHPs under an external electric field have been observed, and the mechanisms for these responses remain a topic of intense debate. In this work, with an external voltage applied to the CHNHPbI crystal, reversible photoluminescence (PL) enhancement and quenching behaviors respectively near the anode and the cathode were observed under wide-field fluorescence microscopy.

Physical insights into protection effect of conjugated polymers by natural antioxidants.

Conjugated polymers (CPs) known as organic semiconductors have been broadly applied in photovoltaic and light emitting devices due to their easy fabrication and flexibility. However, one of the bottlenecks limiting the application of CPs is their poor photostability upon continuous excitation which is one of the crucial parameters of CPs. How to improve the photostability of CPs is always one of the key questions in this field.

A Novel Application of Educational Management Information System based on Micro Frontends.

With the launch of the Education Informatization 2.0 action plan by the Ministry of Education, a large number of college information systems have been born in China. Most of these systems are single page web applications (SPA) based on traditional MVC structures.

Inhibition of Phase Segregation in Cesium Lead Mixed-Halide Perovskites by B-Site Doping.

The emergence of all-inorganic halide perovskites has shown great potential in photovoltaic and optoelectronic devices. However, the photo-induced phase segregation in lead mixed-halide perovskites has severely limited their application. Herein, by real-time monitoring the photoluminescence (PL) spectra of metal mixed-halide perovskites under light irradiation, we found that the photo-induced phase transition can be significantly inhibited by B-site doping.

Identification of the Band Gap Energy of Two-dimensional (OA)(MA)PbI Perovskite with up to 10 Layers.

Two-dimensional (2D) perovskites are attracting broad attention for their stability and wavelength tunability. However, random crystallization of sample preparation makes it difficult to obtain 2D perovskites with pure structure, especially when the number of layers is large. Herein, we prepared 2D perovskite (CHNH)(MA)PbI with different layers ( = 1-10).

Surface plasmon resonance enhanced direct Z-scheme TiO/ZnTe/Au nanocorncob heterojunctions for efficient photocatalytic overall water splitting.

Solar-driven photocatalytic overall water splitting is regarded as one of the ideal strategies to generate renewable hydrogen energy without the initiation of environmental issues. However, there are still a few remaining challenges to develop wide-light-absorption and stable photocatalysts for the simultaneous production of H2 and O2 in pure water without sacrificial reagents. Herein, we report the design and preparation of Z-scheme TiO2/ZnTe/Au nanocorncob heterojunctions by homogeneously decorating Au nanoparticles onto the surface of core-shell TiO2/ZnTe coaxial nanorods for highly efficient overall water splitting.

Amino Acid Encoding Methods for Protein Sequences: A Comprehensive Review and Assessment.

As the first step of machine-learning based protein structure and function prediction, the amino acid encoding play a fundamental role in the final success of those methods. Different from the protein sequence encoding, the amino acid encoding can be used in both residue-level and sequence-level prediction of protein properties by combining them with different algorithms. However, it has not attracted enough attention in the past decades, and there are no comprehensive reviews and assessments about encoding methods so far.

Predicting protein-ligand binding residues with deep convolutional neural networks.

Background: Ligand-binding proteins play key roles in many biological processes. Identification of protein-ligand binding residues is important in understanding the biological functions of proteins. Existing computational methods can be roughly categorized as sequence-based or 3D-structure-based methods.

Photo-induced dual passivation via Usanovich acid-base on surface defects of methylammonium lead triiodide perovskite.

Post-fabrication defect passivation of organometal halide perovskites has become an efficient way to improve their photophysical properties, but the underlying mechanisms are still in debate. In this work, we used p-benzoquinone (p-BQ) to generate surface defects on methylammonium lead triiodide perovskite (MAPbI3), and found that a Usanovich acid-base (O2, acetone or acetonitrile) treatment can effectively passivate those defects and lead to photoluminescence (PL) enhancement. The passivation effect arose from partial neutralization of defect charges via electron transfer between passivation reagents and relevant defects.

Hydrophosphonodifluoromethylation of Alkenes via Thiyl-Radical/Photoredox Catalysis.

Visible-light-induced catalytic hydrophosphonodifluoromethylation of mono- and disubstituted alkenes using bromodifluoromethanephosphonate with a Hantzsch ester as the terminal reductant is reported. The combination of thiyl-radical catalysis with photoredox catalysis is important for achieving good chemoselectivity and high yields.

Aggregation-induced visible light absorption makes reactant 1,2-diisocyanoarenes act as photosensitizers in double radical isocyanide insertions.

The joint computational and experimental efforts reveal that the organic molecule 1,2-diisocyano-4,5-dimethylbenzene (1) acts as both a reactant and a photosensitizer (PS) in a metal-free reaction with perfluoroalkylhalide (2) to produce 2-perfluoroalkyl quinoxalines (3) under visible light. Both the π-π stacking aggregation in crystals and the solvation in various solvents of PS 1 exhibited visible-light absorption at 466 nm in spite of its smaller coefficient than that of the ultraviolet-light absorption. Such an aggregation-assisted visible-light absorption phenomenon is rationalized by theoretical calculations of the condensed-phase properties with the consideration of the explicit polarization effect from the neighboring molecules.