Catalytic performance and mechanism study of the isomerization of 2,5-dichlorotoluene to 2,4-dichlorotoluene.

This work investigates the influence of catalyst HZSM-5 on the isomerization of 2,5-dichlorotoluene (2,5-DCT) to produce 2,4-dichlorotoluene (2,4-DCT). We observe that hydrothermal treatment leads to a decrease in total acidity and Brønsted/Lewis ratio of HZSM-5 while generating new secondary pores. These characteristics result in excellent selectivity for post-hydrothermal modified HZSM-5 in the isomerization reaction from 2,5-DCT to 2,4-DCT. Under atmospheric pressure at 350 °C, unmodified HZSM-5 achieves a selectivity of 66.4% for producing 2,4-DCT, however after hydrothermal modification the selectivity increases to 78.7%. Density Functional Theory (DFT) calculations explore the thermodynamic aspects of adsorption between the HZSM-5 surface and 2,4-DCT. The kinetic perspective investigates the mechanism involving proton attack on the methyl group of 2,5-DCT followed by rearrangement leading to formation of 2,4-DCT during isomerization. The consistency between simulation and experimental results provides evidence for the feasibility of isomerizing 2,5-DCT to 2,4-DCT. This work fills the gap in the low value-added product 2,5-DCT isomer conversion, indicating its significant practical application potential and provides a valuable reference and guidelines for industrial research in this field.

Pseudo-Diastereodivergent Synthesis of Chiral Fluorenes Bearing Bis-1,3-Nonadjacent Stereogenic Centers via Organocatalytic Desymmetrization of meso-Epoxides.

We report an enantio- and diastereodivergent synthesis of enantioenriched fluorenes bearing bis-1,3-nonadjacent stereocenters with broad substrate scope and high enantioselectivity (up to 99% ee) under low catalyst loading (0.1 mol %). The key to the success of this method is the pseudo-diastereodivergent desymmetrization of stereoisomers of meso-epoxides enabled by the same organocatalyst. Furthermore, some of the chiral fluorenes obtained exhibit high fluorescence quantum yields (up to 76.6%), as evidenced by photophysical properties studies.

Synthesis of a versatile 1H-indene-3-carboxylate scaffold enabled by visible-light promoted Wolff rearrangement of 1-diazonaphthalen-2(1H)-ones.

Herein, we have developed a sequential visible-light-promoted Wolff rearrangement of 1-diazonaphthalen-2(1H)-ones, followed by capturing the in situ generated ketene intermediates with various alcohols, producing diverse 1H-indene-3-carboxylates in moderate to good yields under mild reaction conditions. The broad substrate scope, high functional group tolerance, and robust conditions make the resulting derivative a versatile platform for the synthesis of plenty of bioactive molecules.

An Artificial MnWO4 Cathode Electrolyte Interphase Enabling Enhanced Electrochemical Performance of δ-MnO2 Cathode for Aqueous Zinc Ion Battery.

The dissolution of active material in aqueous batteries can lead to a rapid deterioration in capacity, and the presence of free water can also accelerate the dissolution and trigger some side reactions that affect the service life of aqueous batteries. In this study, a MnWO4 cathode electrolyte interphase (CEI) layer is constructed on a δ-MnO2 cathode by cyclic voltammetry, which is effective in inhibiting the dissolution of Mn and improving the reaction kinetics. As a result, the CEI layer enables the δ-MnO2 cathode to produce a better cycling performance, with the capacity maintained at 98.2% (vs. activated capacity at 500 cycles) after 2000 cycles at 10 A g-1. In comparison, the capacity retention rate is merely 33.4% for pristine samples in the same state, indicating that this MnWO4 CEI layer constructed by using a simple and general electrochemical method can promote the development of MnO2 cathodes for aqueous zinc ion batteries.

Enhanced H+ Storage of a MnO2 Cathode via a MnO2 Nanolayer Interphase Transformed from Manganese Phosphate.

The MnO2 cathode has attracted extensive attention in aqueous zinc ion battery research due to its environmental benignity, low cost, and high capacity. However, sluggish kinetics of hydrated zinc ion and manganese dissolution lead to insufficient rate and cycle performances. In this study, a manganese phosphate nanolayer synthesized in situ on a MnO2 cathode can be transformed into a δ-MnO2 nanolayer interphase after activation upon cycling, endowing the interphase with abundant interlayer water. As a result, the δ-MnO2 nanolayer interphase with the function of H+ topochemistry significantly enhances H+ (de)insertion in the MnO2 cathode, which leads to a kinetics conversion from Zn2+-dominated (de)insertion to H+-dominated (de)insertion, thus endowing the MnO2 cathode with superior rate and cycle performances (85.9% capacity retention after 1000 cycles at 10 A g-1). This strategy can be highly scalable for other manganese-based cathodes and provides an insight for developing high-performance aqueous zinc ion batteries.

Copper-doped zeolitic imidazolate frameworks-8/hydroxyapatite composite coating endows magnesium alloy with excellent corrosion resistance, antibacterial ability and biocompatibility.

Magnesium (Mg) and its alloys exhibit an excellent prospect for orthopedic clinical application due to their outstanding biodegradability and mechanical adaptability. However, the rapid corrosion rate/latent device-associated infections may lead to a failed internal fixation of Mg-based implants. Herein, a novel composite coating consisted of outer copper-doped zeolitic imidazolate frameworks-8 and inner hydroxyapatite (Cu@ZIF-8/HA) was in situ constructed on AZ31B Mg alloy via a two-step approach of hydrothermal treatment and seeded solvothermal method. The results verified that the electrochemical impedance of the obtained Cu45@ZIF-8/HA composite coating increased by two orders of magnitude to 6.6013 × 104 Ω·cm2 compared to that of bare Mg alloy. This was attributed to the reduced particle size of ZIF-8 nanoparticles due to the doped copper ions, which could be effectively grown in situ on the micro-nano flower-like structure of the HA-coated Mg alloy. Meanwhile, the Cu@ZIF-8/HA coating exhibited excellent antibacterial properties due to the release of copper ions and zinc ions from Cu@ZIF-8 dissolved in bacterial culture solution. The ICP results unraveled that the released concentration of copper and zinc ions could enhance the activity of alkaline phosphatase in the appropriate range during MC3T3-E1 cell culture in vitro for 7 days. This research revealed that the preparation of multifunctional metal-organic frameworks coating doped with antimicrobial metal ions via the seed layer solvothermal method was significant for studying the antimicrobial properties, osteogenic performance and corrosion resistance of Mg-based bioactive coatings.

Boosted H+ Intercalation Enables Ultrahigh Rate Performance of the δ-MnO2 Cathode for Aqueous Zinc Batteries.

H+ intercalation, as a critical battery chemistry, enables electrodes' high rate performance due to the fast diffusion kinetics of H+. In this work, more water molecules are introduced into δ-MnO2 by the protonation of δ-MnO2 with abundant oxygen vacancies. Benefiting from the structure with a close arrangement of water molecules in interlayers, the Grotthuss transport of proton is achieved in the energy storage of the δ-MnO2 cathode. As a result, the δ-MnO2 cathode exhibits an ultrahigh rate performance with a capacity of 368.1 mAh g-1 at 0.5 A g-1 and 83.4 mAh g-1 at 50 A g-1, which has a capacity retention of 73% after 1100 cycles at 10 A g-1. The study of the storage mechanism reveals that the Grotthuss intercalation of proton predominates the storage process, which empowers the cathode with high rate performance.

SKF-LDA: Similarity Kernel Fusion for Predicting lncRNA-Disease Association.

Recently, prediction of lncRNA-disease associations has attracted more and more attentions. Various computational models have been proposed; however, there is still room to improve the prediction accuracy. In this paper, we propose a kernel fusion method with different types of similarities for the lncRNAs and diseases. The expression similarity and cosine similarity are used for lncRNAs, and the semantic similarity and cosine similarity are used for the diseases. To eliminate the noise effect, a neighbor constraint is enforced to refine all the similarity matrices before fusion. Experimental results show that the proposed similarity kernel fusion (SKF)-LDA method has the superiority performance in terms of AUC values and other measurements. In the schemes of LOOCV and 5-fold CV, AUC values of SKF-LDA achieve 0.9049 and 0.8743±0.0050 respectively. In addition, the conducted case studies of three diseases (hepatocellular carcinoma, lung cancer, and prostate cancer) show that SKF-LDA can predict related lncRNAs accurately.

Application of sub-Doppler DAVLL to laser frequency stabilization in atomic cesium.

We achieve laser frequency stabilization by a simple technique based on sub-Doppler dichroic atomic vapor laser lock (DAVLL) in atomic cesium. The technique that combines saturated-absorption spectroscopy and Zeeman splitting of hyperfine structures allows us to obtain a modulation-free dispersion-like error signal for frequency stabilization. For the error signal, the dependence of peak-to-peak amplitude and the slope at the zero-crossing point on the magnetic field is studied by simulation and experiment. Based on the result, we obtain an available sub-Doppler DAVLL error signal with high sensitivity to the frequency drift by selecting an appropriate strength of the magnetic field. Ultimately, the fluctuation of the locked laser frequency is confined to below 0.5 MHz in a long term, exhibiting efficient suppression of frequency noise.