Baocai Xu

As a natural compound with various biological activities, tangeretin (TAN) has numerous potential advantages in food and medical fields. However, its poor aqueous solubility and bioavailability limit its effective application. In this paper, the mixed monolayer characteristics of different mass fractions of TAN with stearic acid (SA) and dipalmitoyl phosphatidyl choline (DPPC) were investigated. The optimal film-forming composition was obtained by analyzing the molecular area, monolayer compressibility, shrinkage and expansion, and other thermodynamic parameters. The results indicated that there was mutual repulsion between SA and TAN molecules, and the stability of the monolayer was poor. However, TAN/DPPC mixed monolayers exhibited favorable interactions and mutual attraction between the two components. When ω_TAN was 0.2, the minimum excess surface pressure of the TAN/DPPC system was −17.16 mN/m, and the minimum excess Helmholtz free energy was −3413.62 J/mol. At this composition, the intermolecular attraction between DPPC and TAN was strongest, and the mixed monolayer displayed strong deformation resistance and high stability.

It is of great significance to develop a simple and rapid electrochemical sensor for simultaneous determination of heavy metal ions (HMIs) in Baijiu by using new nanomaterials. Here, graphene (GR) was utilized to combine with covalent organic frameworks (COFs) that was synthesized via the aldehyde-amine condensation between 2, 5-dimethoxyterephthalaldehyde (DMTP) and 1, 3, 5-tris(4-aminophenyl) benzene (TAPB) to prepare a new GR/COF_DPTB/GCE sensor for electrochemical sensing multiple HMIs. Compared with the glass carbon electrode (GCE), GR/GCE and COF_DPTB/GCE, the developed sensor exhibited excellent electrochemical analysis ability for the simultaneous detection of Cd²⁺, Pb²⁺, and Cu²⁺ owing to the synergistically increased the specific surface area, the periodic porous network and plenty of effective binding sites, as well as the enhanced conductivity. Under the optimized experimental parameters, the proposed sensor showed good linearity range of 0.1–25 μM for Cd²⁺, and both 0.1–11 μM for Pb²⁺ and Cu²⁺ with the detection limits of Cd²⁺, Pb²⁺, and Cu²⁺ being 0.011 μM, 8.747 nM, and 6.373 nM, respectively. Besides, the designed sensor was successfully applied to the simultaneous detection of the three HMIs in Baijiu samples, suggesting its good practical application performance and a new method for the rapid detection of HMIs being expended.

This study developed an electrochemical sensor for Mn²⁺ assay in Baijiu based on TiO₂-NH₂@COF_DPTB nanocomposite, which was synthesized via the controllable growth of COF_DPTB onto the surface of TiO₂-NH₂ using the Schiff-base condensation reaction.

Heavy metal ions (HMIs) pose a serious threat to the environment and human body because they are toxic and non-biodegradable and widely exist in environmental ecosystems. It is necessary to develop a rapid, sensitive and convenient method for HMIs detection to provide a strong guarantee for ecology and human health. Ion-imprinted electrochemical sensors (IIECSs) based on nanomaterials have been regarded as an excellent technology because of the good selectivity, the advantages of fast detection speed, low cost, and portability. Electrode surfaces modified with nanomaterials can obtain excellent nano-effects, such as size effect, macroscopic quantum tunneling effect and surface effect, which greatly improve its surface area and conductivity, so as to improve the detection sensitivity and reduce the detection limit of the sensor. Hence, the present review focused on the fundamentals and the synthetic strategies of ion-imprinted polymers (IIPs) and IIECSs for HMIs detection, as well as the applications of various nanomaterials as modifiers and sensitizers in the construction of HMIIECSs and the influence on the sensing performance of the fabricated sensors. Finally, the potential challenges and outlook on the future development of the HMIIECSs technology were also highlighted. By means of the points presented in this review, we hope to provide some help in further developing the preparation methods of high-performance HMIIECSs and expanding their potential applications.

A new type of NADH model compound, which has six asymmetric carbon centers, has been synthesized by an efficient and convenient method. We preliminarily attempted that NADH models combined with enzyme were used in the asymmetric reduction. It is the first time that dehydrogenase with NADH models instead of inorganic catalysts such as MgCl2 were used in the asymmetric reduction. Furthermore, the experimental results showed that the new NADH model has the strongest fluorescence emission properties compared with previous reported models.

High-nitrogen energetic compounds are widely used in military and civil fields. To cope with some special conditions, materials with high melting point and good heat resistance are required. Herein, synthetic approach of two TACOT-derived compounds with high heat resistance and strong insensitivity for friction has been optimized. Significantly, 100 g-scale of aza-TACOT(I) was prepared with a total yield of 80% and a purity of 99.9%. Meanwhile, aza-TACOT(II) was obtained with a purity of 98.9% under the optimized conditions. This practical method features scalable and simple operations. In addition, an acceptable mechanism was firstly proposed for the critical step. Graphical Abstract

DMSO‐TsCl has been developed for direct methylthiolation of various electron‐rich heteroarenes (more than 40 examples) with high regioselectivity in moderate to excellent yields (up to 96 %). Especially, pyrroles, furans, and thiophenes can be efficiently mono‐methylthiolated. This practical method features scalable, metal‐free, mild conditions and is compatible with air and moisture. Several applications of methylthiolated products were demonstrated for the first time. Based on controlled experimental results, a plausible mechanism was proposed with two key intermediates involved in the mechanism being detected by HRMS.

N-lauroyl-L-Valine sodium (NLLVS) was synthesized and characterized by FT-IR, ¹H-NMR spectrometry. Surface and interface tension were measured by wilhelmy plate and spinning drop method. The effects of surfactant concentration, salt, polymer and mixed surfactant on interfacial tension were studied in detail. The critical micelle concentration (cmc) was 6 × 10⁻³mol/L and cmc _oil was 8 × 10⁻³mol/L. The equilibrium interfacial tension (IFT_equ) first decreased and then increased with NLLVS increasing. Mixed salts were less effective at reducing interfacial tension than NaCl and CaCl₂, while the higher concentration of NaCl was needed to obtain the same IFT as added CaCl₂ and NaCl/CaCl₂. The lowest IFT_equ obtained at the NaCl concentration of 10% when the ratio of NLLVS and Alkyl polyoxypropylene polyoxyethylene ether sulfate (P12) was 2:8. Polyacrylamide was disadvantage to reduce IFT, while polyacrylamide was arranged more tightly by NLLVS. Graphical Abstract

The effect of metal ions and surfactants on the enzymatic hydrolysis of pretreated wheat straw lignocellulose was investigated. Scanning electron microscopy, infrared spectrum analysis, dynamic light scattering, and fluorescence spectra analysis were used to characterize the influence of Fe3+/ polyoxyethylene (20) sorbitan monooleate (Tween 80). The interaction between Fe3+/Tween 80 and enzyme was further investigated by enzyme kinetics and enzyme activity measurements. The best synergistic effect was obtained when the ratio of Fe3+ and Tween 80 was 0.06. The scanning electron microscopy images showed that the Fe3+/Tween 80 combination was associated with high porosity substrates. The infrared spectrum analysis indicated that the components of the substrates depended on additive types. The highest relative enzymatic activity increase rate was obtained with added Fe3+/ Tween 80. The Vmax and Km values of the group with added Fe3+/Tween 80 were much higher than that of the group without additives. With the addition of Fe3+/ Tween 80, the intensity of the fluorescence emission peak decreased and the peak shifted towards a longer wavelength.

The foam and rheological properties of four extended surfactants C_12–14P_mE₂S (m = 0, 3, 5, and 8) of four different concentrations were investigated in this paper. The foam properties, including, foamability, foam stability, liquid carrying ability, foam drainage and foam morphology were characterized. The rheological measurements were carried out through frequency sweep in the oscillation mode. The foamability and foam stability decreased with increasing numbers of PO groups embedded in those surfactants. At the same concentration, the longer the PO chain of the surfactant molecule, the larger the liquid carrying capacity of the foam. The foaming number decreases as the time increases, and longer PO chains were associated with faster foam number decline. The rheological measurements show that those surfactant solutions are “liquid-like”. With increasing surfactant concentration, the viscous modulus of C_12–14P₈E₂S increases gradually, whereas that of C_12–14E₂S decreases.