New Alkylated Purine Derivatives from Colletotrichum sp. F169

Chemistry of Natural Compounds - An endophytic strain F169 was isolated from the plant Huperzia serrata. It was identified as Colletotrichum sp. based on the sequence at the internal transcribed...     

Crystal rigidifying strategy toward hybrid cadmium halide to achieve highly efficient and narrowband blue light emission

Highly efficient and narrowband blue light-emitting performance is extremely crucial for the optoelectronic applications of organic-inorganic hybrid perovskites. However, the not yet viable approach has been shown to simultaneously improve photoluminescence quantum yield (PLQY) and narrow linewidth of blue light emission. Herein, a new crystal rigidifying strategy is proposed as a viable dual-optimization avenue. Specifically, we perform a post-synthetic technique on hybrid cadmium halides and successfully convert zero-dimensional (0D) DMP-0-CdBr₄ to one-dimensional (1D) DMP-1-CdBr₃, accompanied by luminescent transformation from sky-blue (470 nm) to deep-blue (432 nm) emissions. The structural evolution from discrete block to infinite chain significantly enhances the crystal rigidity, which results in narrower emission linewidth (89 to 50 nm) and increased color purity (74.5% to 96.7%). Synchronously, the PLQY also realizes a notable enhancement from 14.0% to 52.3%. Systematical characterizations demonstrate that enhanced crystal rigidity simultaneously weakens the electron-phonon interaction and slows down nonradiative decay, which narrows the emission linewidth and boosts the PLQY. The highly efficient light-emitting performance enables them as excellent down-conversion blue phosphors to fabricate solid-state LED giving bright warm white light with high color rendering index of 95.4. This work paves a novel structural optimization way to rationally design or fine-tune high-performance blue-light emitting halides.     

Stronger Versions of Sensitivity for Minimal Group Actions

Acta Mathematica Sinica, English Series - We study several stronger versions of sensitivity for minimal group actions, including n-sensitivity, thick n-sensitivity and blockily thick n-sensitivity,...     

Numerical calculation and experimental measurement of temperatures and welding residual stresses in a thick-walled T-joint structure

Journal of Thermal Analysis and Calorimetry - In this investigation, a T-joint numerical welding simulation of thick steel plates is performed to estimate transient temperature distributions,...     

Low Mach number limit of global solutions to 3‐D compressible nematic liquid crystal flows with Dirichlet boundary condition

In this paper, we consider the uniform estimates of strong solutions in the Mach number ? and t ∈ [0,∞) for the compressible nematic liquid crystal flows in a 3‐D bounded domain , provided the initial data are small enough and the density is close to the constant state. Here, we consider the case that the velocity field satisfies the Dirichlet boundary condition. Based on the uniform estimates, we obtain the global convergence of the compressible nematic liquid crystal system to the incompressible nematic liquid crystals system as the Mach number tends to zero.     

Bulk Mn2+ Doped 1D Hybrid Lead Halide Perovskite with Highly Efficient,Tunable and Stable Broadband Light Emissions

Mn²⁺ doped colloidal three-dimensional (3D) lead halide perovskite nanocrystal (PNC) has attracted intensive research attention; however, the low exciton binding energy and fatal optical instability of 3D PNC seriously hinder the optoelectronic application. Therefore, it remains significant to explore new stable host perovskite with strongly bound exciton to realize more desirable luminescent property. In this work, we utilized bulk one-dimensional (1D) hybrid perovskite of [AEP]PbBr₅ ⋅ H₂O (AEP=N-aminoethylpiperazine) as structural platform to rationally optimize the luminescent property by a controllable Mn²⁺ doping strategy. Significantly, the series of Mn²⁺-doped 1D [AEP]PbBr₅ ⋅ H₂O show enhanced energy transfer efficiency from the strongly bound excitons of host material to 3d electrons of Mn²⁺ ions, resulting in tunable broadband light emissions from weak yellow to strong red spectral range with highest photoluminescence quantum yield up to 28.41 %. More importantly, these Mn²⁺-doped 1D perovskites display ultrahigh structural and optical stabilities in humid atmosphere, water and high temperature exceeding the conventional 3D PNC. Combined highly efficient, tunable and stable broadband light emissions enable Mn²⁺-doped 1D perovskite as excellent down-converting phosphor showcasing the potential application in white light emitting diode. This work not only provides a profound understanding of low-dimensional perovskites but also opens a new way to rationally design high-performance broadband light emitting perovskites for solid-state lighting and displaying devices.     

Superhydrophobic,strong and transparent paper made from cellulosic fibers

Cellulose - Superhydrophobic and strong cellulosic paper was fabricated in a two-step process consisting of heavy refining and dip coating with PDMS (trimethylsiloxy-terminated poly...     

NIR-II Fluorescent Brightness Promoted by “Ring Fusion” for the Detection of Intestinal Inflammation

Fluorophores with emission in the second near-infrared window (NIR-II) have displayed salient advantages for biomedical applications. However, the common strategy of reducing the energy bandgap of fluorophores so as to achieve red-shifted wavelengths always leads to compromised fluorescent brightness. Herein, we propose a molecular design concept of “ring-fusion” to modify the acceptor of AIEgen that can extend the luminous wavelength from NIR-I to NIR-II. The fused-acceptor-containing fluorophore yielded, TTQP, has an enhanced absorption coefficient with a higher brightness in nanoparticle formation compared to its NIR-I emissive counterpart (TTQ-DP) with a non-fused acceptor. Theoretical calculation further confirms that the ring fusion can efficiently promote the rigidity and planarity of the electron-deficient core, leading to a lower reorganization energy and nonradiative decay. The TTQP NPs yielded thus allow sensitive NIR-II fluorescence imaging of vasculature and intestinal inflammation in mice models. Therefore, we anticipate that our work will provide a promising molecular-engineering strategy to enrich the library and broaden the application scope of NIR-II fluorophores.     

S-(Trifluoromethyl)Benzothioate (TFBT): A KF-Based Reagent for Nucleophilic Trifluoromethylthiolation

S-(Trifluoromethyl)benzothioate (TFBT) has been developed as an inexpensive, bench-stable, and user-friendly trifluoromethylthiolation reagent, which can be easily synthesized by using KF as the only fluorine source. By using TFBT, trifluoromethylthiolates with various counterions can be readily obtained. The synthetic application of TFBT was demonstrated by trifluoromethylthiolation-halogenation of arynes, bis(trifluoromethylthiolation)–halogenation of 1,2-benzdiynes, nucleophilic substitution of alkyl halides, deoxytrifluoromethylthiolation of alcohols, and cross-coupling with aryl and vinyl boronic acids.