Optimization of an Alkaline Hydrolysis Preparation of Capilliposide-A from Lysimachia capillipes Hemsl. Using Response Surface Methodology Coupled with HPLC-ELSD Analysis

Capilliposide-A, a rare secondary saponin found in Lysimachia capillipes, has been reported to exhibit good biological activities. However, it is difficult to obtain a sufficient of capilliposide-A for further research through column chromatography and chemical synthesis. The aim of this work was to establish an efficient approach for the convenient preparation of this steroid saponin based on alkaline hydrolysis. The hydrolysis conditions were optimized by response surface methodology after a preliminary investigation of the affecting factors by single-factor experiments. Under the optimal conditions, the macroporous resin that adsorbed capilliposide-B and capilliposide-C was hydrolyzed in an 8% (w/v) NaOH solution at 35 °C for 65 h, and the yield of capilliposide-A was 68.90%. The results demonstrated that this newly developed approach is efficient for the preparation of capilliposide-A, and this approach is also crucial for further development and clinical applications.

     

弹性蛋白酶生物催化酯水解的综合实验设计*

酯的水解是有机化学实验教学中的一个重要化学反应,传统的酯水解实验设计是利用酸性或碱性环境在加热的条件下进行水解,而本实验设计将酯水解与生物催化相结合,利用弹性蛋白酶的水解功能,在常温及中性环境下实现对4-三氟甲基-7-丙酰氧基香豆素的水解。该实验设计创新性地将酯水解和酶催化相结合,有利于拓展学生的知识面,培养化学生物学复合型人才。同时,生物催化反应具有反应温和、环境友好等特点,符合当代绿色化学的需求。     

Luminescent Thin Films Enabled by CsPbX3 (X=Cl,Br, I) Precursor Solution

Inorganic cesium lead halide perovskite nanocrystals are candidates for lighting and display materials due to their outstanding optoelectronic properties. However, the dissolution issue of perovskite nanocrystals in polar solvents remains a challenge for practical applications. Herein, we present a newly designed one-step spin-coating strategy to prepare a novel multicolor-tunable CsPbX₃ (X=Cl, Br, I) nanocrystal film, where the CsPbX₃ precursor solution was formed by dissolving PbO, Cs₂CO₃, and CH₃NH₃X into the ionic liquid n-butylammonium butyrate. The as-designed CsPbX₃ nanocrystal films show high color purity with a narrow emission width. Also, the blue CsPb(Cl/Br)₃ film demonstrates an absolute photoluminescence quantum yields (PLQY) of 15.6 %, which is higher than 11.7 % of green CsPbBr₃ and 8.3 % of red CsPb(Br/I)₃ film. This study develops an effective approach to preparing CsPbX₃ nanocrystal thin films, opening a new avenue to design perovskite nanocrystals-based devices for lighting and display applications.     

Effects of C3-aromatic heterocycles on 1,3,5-triaryl-2-pyrazoline sulfonium salt photoacid generators as light-emitting diode-sensitive cationic photoinitiators

Four 1,5-diphenyl-3-aromatic heterocyclyl-2-pyrazoline-based sulfonium salt photoacid generators (PAGs) with different aromatic heterocycles substituted on C3 atom and dimethyl sulfonium group on C5 atom were synthesized. These PAGs were highly photosensitive in the 365–425 nm light-emitting diode region, and the intramolecular charge transfer from the pyrazoline ring to sulfonium salts induced efficient photolysis and high Φ_H⁺. The heterocycles as well as their substituted positions significantly influenced the energy of the S₂ orbital, which was determined by the electrochemical and absorption properties of the PAGs. The raising of the S₂ orbital energy enlarged the energy gap of S₀–S₂ and S₁–S₂, resulting in blue shift of the absorption spectra and increase in the quantum yield of photoacid generation (Φ_H⁺), respectively. When the energy of excited electrons was higher than that of the S₂ orbital, the transition from S₀ to S₂ (π–π*) occurred before the C-S cleavage on S₁ and the PAGs showed high Φ_H⁺ values (0.52–0.72). The transition from S₀ to S₁ (π–σ*) occurred when the energy of electrons is lower than that of the S₂ orbital, and the PAGs showed low Φ_H⁺ value. The photopolymerization kinetics demonstrated that these PAGs were highly efficient cationic photoinitiators.     

Laplacian Perfect State Transfer in Extended Neighborhood Coronas

Acta Mathematica Sinica, English Series - In this paper, we give some sufficient conditions for extended neighborhood coronas to have Laplacian perfect state transfer. We also give some conditions...     

Dye Sensitization Offers a Brighter Afterglow Nanoparticle Future for in vivo Recharged Luminescent Imaging

While concerns about improving recharged afterglow intensity in vivo still motivate further exploration, afterglow nanoparticles (AGNP) offer unique optical merit for autofluorescence-free biological imaging. Apart from efforts enhancing the afterglow emission properties of AGNP, improving afterglow excitation response to visible or near infrared light is important but has lacked success. Dye sensitization has been used to improve the optical response of photovoltaic nanomaterials and to enhance upconversion luminescence efficiency. This concept has recently been expanded and applied to AGNPs. As a new multifunctional nanoprobe, such dye-sensitized AGNP takes advantage of both high spatial resolution fluorescence imaging and sensitive afterglow imaging. This Concept introduces the background, the concept, mechanism, and related imaging application, as well as reviewing existing challenges and proposing future developmental directions for the dye-sensitized AGNPs.     

A new MnxOy/carbon nanorods derived from bimetallic Zn/Mn metal–organic framework as an efficient oxygen reduction reaction electrocatalyst for alkaline Zn-Air batteries

Journal of Solid State Electrochemistry - In this work, nanorods like bimetallic Zn/Mn metal–organic-frameworks (MOFs) are proposed as the precursor for preparing MnxOy/porous carbon...     

Computational Insights into the Allosteric Effect and Dynamic Structural Features of the SARS-COV-2 Spike Protein

COVID-19 caused by SARS-COV-2 is continuing to surge globally. The spike (S) protein is the key protein of SARS-COV-2 that recognizes and binds to the host target ACE2. In this study, molecular dynamics simulation was used to elucidate the allosteric effect of the S protein. Binding of ACE2 caused a centripetal movement of the receptor-binding domain of the S protein. The dihedral changes in Phe329 and Phe515 played a key role in this process. Two potential cleavage sites S1/S2 and S2′ were exposed on the surface after the binding of ACE2. The binding affinity of SARS-COV-2 S protein and ACE2 was higher than that of SARS-COV. This was mainly due to the mutation of Asp480 in SARS-COV to Ser494 in SARS-COV-2, which greatly weakened the electrostatic repulsion. The result provides a theoretical basis for the SARS-COV-2 infection and aids the development of biosensors and detection reagents.     

Multiplasmid DNA in agarose gel electrophoresis: Suitable dye and temperature is essential for prominent profiles

Nucleic acids dye Goldview is widely used in agarose gel electrophoresis (AGE). However, in this study, a sample of multiplasmid DNA (multi-pDNA) stained with Goldview analyzed by AGE showed its instability at low temperature. Three types of DNA samples were analyzed, including linear DNA (ladder), single-plasmid DNA (single-pDNA), and multi-pDNA, electrophoretic conditions were optimized by adjusting the dye, the buffer, and the temperature (1–50°C). The results showed that the light intensity of Gelred is 2.2-times higher than that of Goldview in staining multi-pDNA. Compared with the single-pDNA and the linear DNA, the multi-pDNA stained with Goldview was greatly affected by temperature. This short communication indicated that Gelred is a highly applicable dye for analyzing multiplasmid samples. The degree and the way of binding of Goldview to multi-pDNA are greatly affected by temperature.     

Linear codes from support designs of ternary cyclic codes

Designs, Codes and Cryptography - For a long time, the literature has demonstrated that designs and codes are exciting topics for combinatorics and coding theory. Linear codes and t-designs are, in...