In this study, we prepared and applied polymeric porous microsphere adsorbents with selectivity for Li⁺ extraction from aqueous solution. We synthesized the adsorbents by suspension polymerization using methacryloyoxyme-12-crown-4 (M12C4) as a functional monomer, which had been synthesized from 2-hyroxymethyl-12-crown-4 and methacryloyl chloride. We verified the chemical composition by solid nuclear magnetic resonance (¹³C-NMR) spectroscopy and observed the porous structure by scanning electron microscopy (SEM). We conducted adsorption isothermal and kinetic tests to determine the adsorption properties. It was found that the adsorbents showed high adsorption efficiency and an adsorption equilibrium time of 200 min. In addition, since the crown ether used in this work could form a stable complex with Li⁺, we observed good selectivity for Li⁺ in the prepared solution compared with other ions such as Na⁺, K⁺, Mg²⁺, and Ca²⁺. We reused the adsorbents five times with no significant decrease in adsorptive capacity.

In this paper, the gelation mechanism of erythromycin ethylsuccinate (EES) during crystallization is investigated for the first time. The generated semisolid gel-like phase exhibited a 3D fibrillar network morphology and the typical rheological properties of gels. The fibers inside the gel-like phase were confirmed to be new types of EES solvates using powder X-ray diffraction, thermogravimetric analysis/differential scanning calorimetry, and gas chromatography. The gelation and crystallization regions in EES-1-propanol solid–liquid phase diagram were determined. Analyses of solvent parameters showed that moderate solvent polarity may promote EES gelation. Fourier transform infrared spectra, nuclear magnetic resonance spectra, and scanning electron microscopy analyses indicated that through intermolecular hydrogen bonds, EES and solvent molecules assembled into fibers via crystallographic mismatch branching growth. The fibers intertwined into a 3D network microstructure and formed a gel-like phase, completely immobilizing the solution.

In this paper, we report a new catalytic system for realizing the rapid and efficient oxidation of 5-hydroxymethylfurfural (HMF). First, we used 9-azabicyclo [3.3.1]nonan-3-one-N-oxyl (keto-ABNO) as a catalyst for the aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) in acetic acid. Then, we systematically studied the important reaction parameters, including the solvent, co-catalyst, and temperature. The results demonstrate that the acidic solvent used is crucial for the efficient oxidation of HMF to DFF. Under optimal conditions, we achieved a 93.4% yield of DFF within half an hour at room temperature. We also proposed the possible mechanism for this system.

Flow-induced vibrations in heat exchanger tubes have led to numerous accidents and economic losses in the past. Fluidelastic instability is the most critical flow-induced vibration mechanism in heat exchangers. Both experimental and computational studies conducted to determine fluidelastic instability were presented in this paper. In the experiment, a water channel was built, and a closely packed normal square tube array with a pitch-to-diameter ratio of 1.28 was tested, and significant fluidelastic instability was observed. A numerical model adopting large-eddy simulation and moving mesh was established using ANSYS CFX, and results showed good agreement with the experimental findings. The vibration behaviors of fluidelastic instability were discussed, and results showed that the dominant vibration direction of the tubes changed from streamwise to transverse beyond a critical velocity. A 180° phase lag between adjacent tubes was observed in both the experiment and simulations. Normal and rotated square array cases with pitch-to-diameter ratios of 1.28 and 1.5 were also simulated. The results of this study provide better insights into the vibration characteristics of a square tube array and will help improve the fundamental research and safety design of heat exchangers.

Novel Ni/ZnO–HZSM-5 adsorbents were synthesized by incipient wetness impregnation. The Ni/ZnO–HZSM-5 adsorbent can achieve deep desulfurization and olefin aromatization at the same time. Thiophene sulfur was removed from 495 to less than 10 ppm via reactive adsorption desulfurization (RADS). Olefins were also converted into aromatics. HZSM-5 did not only support adsorbents but also cooperated with active Ni sites to catalyze olefins into aromatic hydrocarbons. Aromatization of 1-pentene, 2-pentene, 2-methyl-2-butene, and 1-hexene on adsorbents was investigated. The adsorbents were characterized by the Brunauer–Emmett–Teller, X-ray diffraction, temperature-programmed reduction, and temperature-programmed desorption of ammonia and thermogravimetric analysis. The experimental results showed that strong acids on the adsorbent disappeared after HZSM-5 loaded active metal sites, and almost no coke was generated on adsorbents in RADS.

In our study, the mechanical properties and degradability of vascular grafts made from poly(ε-caprolactone) (PCL) and poly(lactic-co-glycolic acid) (PLGA) at different ratios were investigated. The results showed that the electrospun PCL/PLGA grafts possess good mechanical properties and biodegradability. The tensile and burst strength of the scaffolds met the demands of vascular grafts. In vitro degradation tests indicated that the degradation rate of the materials increased with the percentage of PLGA, and in vivo tests showed that increasing the amount of PLGA is an effective way to promote cell infiltration. Particularly, the electrospun PCL/PLGA blended scaffold with 10% PLGA exhibited a balance of mechanical and degradation properties, making it a promising tissue engineering material for vascular grafts.

A strain with high production of exopolysaccharide (EPS) was isolated from dried milk cake (a traditional fermented food from Inner Mongolia). The strain was called N21 and later identified as Leuconostoc citreum (Leu. citreum). The strain was cultured in Man-Rogosa-Sharpe medium containing 50 g/L of sucrose for 48 h at 30 °C and the EPS purified, with a yield of 24.5 g/L. An average molecular weight of 6.07 × 10⁶ g/mol was determined by high-performance size-exclusion chromatography. The structure of the purified EPS was investigated through gas chromatography, ¹H and ¹³C nuclear magnetic resonance spectroscopy, and Fourier transform infrared spectroscopy. The results demonstrated a polysaccharide composed of D-glucopyranose units in a linear chain with consecutive α (1 → 6) linkages. No branching was found in the structure of the exopolysaccharide. The purified EPS showed high water solubility and emulsibility. Based on the thermogravimetric curve, the degradation temperature of the EPS was 308.47 °C, which suggested that the dextran in the study exhibited high thermal stability. The results indicated that Leu. citreum N21 could be widely used to produce linear EPS and that the EPS has potential applications in food science and processing as a food additive.

A series of PtCuCeMgAl quintuple hydrotalcite-like compounds with different Ce contents were synthesized by one-pot method. After calcining and reduction, CeO₂-modified Mg(Al)O-supported Pt–Cu alloy catalysts were obtained. To understand the effect of Cu and Ce, the structure and physico-chemistry properties of the catalysts were characterized and analyzed, and the catalytic behaviors were investigated in a direct dehydrogenation of propane to propene. The results show that the Pt⁴⁺, Cu²⁺, and Ce³⁺ ions can be incorporated into the brucite-like layers and the Ce content significantly affects the interaction strength between Pt and Cu and the dehydrogenation performance of propane. Under the reaction conditions, the highest propane conversion (45%) with 89% selectivity to propene and a 40% propene yield were achieved with a 0.3 wt% Ce-modified PtCu/Mg(Al)O catalyst. The improved catalytic performance is related to the easy formation of Pt–Cu alloy phase, excellent resistance to sintering, and coke deposits of active components modified by CeO₂.

In this study, we applied a novel, mild, and convenient synthetic method involving the oxidative cyclization of 1-(pyrazin-2-yl)guanidine derivatives to produce [1,2,4]triazolo[4,3-a]pyrazin-3-amines. We optimized the reaction procedure to easily obtain 5-chloro-[1,2,4]triazolo[4,3-a]pyrazin-3-amine. Various types of halogenated pyrazines can successfully undergo this process. We synthesized a series of 1-(pyrazin-2-yl)guanidines and [1,2,4]triazolo[4,3-a]pyrazin-3-amines, and then elucidated their structures based on their ¹H-NMR, ¹³C-NMR, ESI-HRMS, and nuclear Overhauser effect spectra.

This study investigated indium tin oxide (ITO) films that were deposited on fluororesin-46 (F46) and polyimide (PI) transparent flexible substrates by a DC magnetron sputtering system. The optical properties of ITO films on F46 and PI including transmittance and reflectance in visible, near-infrared, and infrared spectral regions were obtained, and the surface morphology, and optical and electrical properties of ITO/F46 and ITO/PI after vacuum ultraviolet irradiation were investigated. The results showed that the mean transmittances of ITO/F46 and ITO/PI decreased and the sheet resistance increased after the irradiation, and these effects were mainly attributed to the greater surface roughness and crystal defects caused by the irradiation.