A low-cost and easily prepared manganese carbonate (MnCO₃) has been synthesized for catalytic conversion of 5-hydroxymethylfurfural (5-HMF) to 2,5-diformylfuran (DFF). The properties and morphology of the manganese carbonate were measured by SEM, XRD, TGA, BET and XPS. In this method, no harsh reaction conditions were required, and it was a simple and green process for the oxidation of 5-HMF into DFF. To achieve an optimum DFF yield, different reaction conditions, including reaction temperature, reaction time, catalyst amount, and solvents were investigated. Results from the experiments indicated that the highest DFF yield of 86.9% was obtained at 120 °C under atmospheric oxygen pressure after 6 h. Finally, MnCO₃ could be used at least five times with considerable stability.

In this study, particle image velocimetry was applied to investigate flow fields of wormlike micelle (WLM) fluids in a mixing tank equipped with a four-blade, down-pumping, pitched blade turbine. First, the rheology of WLM fluids was investigated, and the Carreau model was utilized to describe their apparent viscosity. Then, the effects of the rotation speeds and rheological properties on the flow fields were studied using different WLM fluids at different rotation speeds. The results revealed that with increasing Reynolds number, the discharge angle decreases and the carven size increases. Furthermore, elastic effects of WLM fluids lead to a more curved flow and a smaller carven.

In this study, we investigated the effects of 6-benzylaminopurine (6-BA)–calcium chloride (CaCl₂)–salicylic acid (SA) treatment on the yellowing and reactive oxygen metabolism of harvested broccoli heads. We dipped fresh broccoli heads in a compound solution (0.6 mmol/L 6-BA + 40 mmol/L CaCl₂ + 3 mmol/L SA) for 5 min and then stored them at 23 °C for 4 days. The results showed that the 6-BA–CaCl₂–SA postharvest treatment effectively retarded the increase in color values (e.g., variations from black to white, from green to red, and from blue to yellow) and the decline in chlorophyll content of the broccoli heads. Compared with the control broccoli, the rate of superoxide anion radical (O₂ ^·−) production and the hydrogen peroxide (H₂O₂) content were lowered by the treatment. We also found significant differences in the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in the treated broccoli. Based on these results, we consider 6-BA–CaCl₂–SA to inhibit the accumulation of reactive oxygen, delay the degradation of chlorophyll, and prolong the shelf life of broccoli heads at 23 °C.

Brookite TiO₂, the latest TiO₂ photocatalyst, promises to be an interesting candidate for photocatalytic applications because of its unique physical and chemical properties. In this study, pure-phase brookite TiO₂ with a quasi-spherical nanostructure was successfully synthesized via a solvothermal method using tetrabutyl titanate (Ti(OC₄H₉)₄, TBOT) as the Ti source in the presence of oxalic acid. NaOH was used to regulate the pH of solution. The structure and morphology of the samples were then analyzed using multiple methods, such as X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) measurements and ultraviolet–visible diffuse spectroscopy (UV–Vis). Photocatalytic activities of the as-synthesized brookite TiO₂ were evaluated by degrading aqueous methylene blue solution under UV light irradiation. The effect of thermal treatment temperature on photocatalytic activity of the samples was also investigated. The produced brookite TiO₂ nanopowders calcined at 500 °C for 2 h showed the highest photocatalytic activity, and the corresponding degradation rate of methylene blue (10 mg/L) reached 96.7% after 90 min of illumination. In addition, the formation mechanism of pure-phase brookite TiO₂ was investigated. It was found that the formation of pure-phase brookite TiO₂ in this study was ascribed to the combined action of oxalic acid and sodium hydroxide.

Ni₂P/ZrO₂-SBA-15 catalysts with different zirconium n-propoxide/SBA-15 mass ratios were synthesized to evaluate their dibenzothiophene hydrodesulfurization catalytic activity. Effect of ZrO₂ introduction was investigated. Supports and catalysts were characterized by BET, XRD, ²⁹Si NMR, XPS and FTIR. The results indicated that zirconium was incorporated into SBA-15 in the forms of [(–O–)₂Si(–O–Zr)₂] and/or [(–O–)₃Si–O–Zr], and that the SBA-15 framework structure was maintained after incorporation of ZrO₂. With zirconium content increasing, ZrO₂ was transformed from amorphous phase to tetragonal phase. Zirconium incorporation into SBA-15 supports could facilitate to form more dispersed Ni₂P active phase. There might be some interaction occurring between the P and Zr species. In addition to Ni₂P, another kind of active phase, ZrP, was formed, which might exhibit a better HDS activity than Ni₂P. It was observed that at a temperature of 280 °C, pressure of 3.0 MPa, WHSV of 6.5 h⁻¹ and H₂ to oil ratio of 450, the Ni₂P/Zr-SBA(1.5) catalyst, where 1.5 represents zirconium n-propoxide/SBA-15 mass ratio, showed the highest DBT conversion, which was 86.6%, almost 35% higher than that of the Ni₂P/Zr-SBA(0) catalyst.

This study provides a detailed report on the synthesis of spherical activated carbon with mesoporous structure using a soluble low molecular weight phenolic resol precursor through an ammonium alginate assisted sol–gel method. The effects of calcinating temperature and the addition of CaCO₃ as a pore-enlarging agent on texture structure and catalytic performance in isobutane dehydrogenation to isobutene were investigated. Characterization of N₂ sorption, mechanical strength tests, and optical photographs confirmed that the obtained carbon materials had high mechanical strength, a good degree of sphericity, and a large surface area. Introducing CaCO₃ as a pore-enlarging agent during the preparation process promoted the formation of a mesoporous structure of carbon spheres and evidently increased the surface area and oxygen content, which can improve isobutane conversion and isobutene selectivity of these carbon spheres. The conversion of isobutane reached up to 28% for this spherical activated carbon, and the selectivity of isobutene reached up to 96%. Isobutane conversion increased with an increase in calcination temperature due to an increase in the oxygen content, whereas the selectivity of isobutene decreased due to the slight decrease in the specific surface area.

Active Fe- and Mn-loaded MCM-41 (Fe–Mn/MCM-41), which was synthesized via a hydrothermal reaction followed by impregnation, is used in the heterogeneous Fenton reaction to degrade methyl orange (MO) in aqueous solution. The synthesized samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N₂ adsorption–desorption isotherm analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Compared with Fe/MCM-41 and Mn/MCM-41, Fe–Mn/MCM-41 showed higher activity for MO degradation and mineralization. Effects of various operating parameters, such as pH, Mn content, and H₂O₂ dosage, on the degradation process were subsequently investigated. Results of experiments on the effect of radical scavengers revealed that the degradation of MO could be attributed to oxidation by HO·. The synergy of Fe and Mn species in the Fenton oxidation process was also explained.

The complex heat of BF₃ with methanol was measured by utilizing the principle of the Bunsen ice calorimeter. The complex heat of BF₃–methanol was found to be 49.2 and 58.1 kJ/mol when the molar ratio of BF₃ to methanol was 1:2 and 1:1, respectively. In addition, the complex heat of BF₃–anisole was also measured to test the apparatus error. The BF₃–anisole result showed a calorimeter value of 53.1 kJ/mol with a system error of 2.3% as compared with the value reported in the literature. The mechanism of the reaction of BF₃ and methanol was interpreted based on our obtained results. This apparatus is useful and suitable for measuring the heat of other liquid–gas and liquid–liquid reactions.

To measure the latency between human motion stimulation and stereo image display response in a visual feedback-based minimally invasive surgical (MIS) robotic system, a method was proposed by comparing the orientations of input and output events through image-processing technology. This method used a black bar to keep pace with the measured joint rotating at a number of speeds. During tests, an external camera was placed in front of the apparatus with a proper visual field, so that it can simultaneously view orientations of both bars fixed on the corresponding joints. After quantitatively analyzing the accuracy of the proposed measurement method, the method was applied to a visual feedback-based master–slave robotic system with two-degrees-of-freedom. Experimental results show that the latency of the overall system was approximately 250 ms, and the opposite clearance of the measured joint was in the range of 1.7°–1.9°.

Shear failure in panel zones and plastic hinges in steel beams are the two major failure modes of connections between concrete-filled steel tubular (CFST) columns and steel beams. To investigate the behavior of this type of connection in both modes, two through-diaphragm connections were tested under cyclic and monotonic loadings and the load-carrying capacity, ductility, and strength of degradation of connections were discussed. Using ABAQUS software, we developed nonlinear finite-element models (FEMs) to simulate the load-carrying capacity and failure modes of the connections under monotonic loading. The finite-element (FE) analysis and test results showed reasonable agreement for the through-diaphragm connections, which confirms the accuracy of FEMs in predicting the load-carrying capacity and failure modes of connections. Based on the validated FEM, a parametric study was then conducted to investigate the influence of the thicknesses of the tube and diaphragm on the load-carrying capacity and failure modes of these connections. The results indicate that the strength, stiffness, and load-carrying capacity are influenced less by the thickness of the diaphragm, and more by the thickness of the steel tube. According to the FE analysis results, it can be found that the critical condition between the two failure modes is determined by the shear resistance and bending resistance.