基于步冷试验的2.25Cr-1Mo-0.25V钢母材及焊缝回火脆化研究

对原始态、步冷态、脱脆态和脱脆步冷态2.25Cr-1Mo-0.25V钢母材及焊缝冲击试验结果进行分析,得到了母材和焊缝在不同状态下的韧脆转变温度vTr54.2和FATT以及脆化度ΔvTr54.2和ΔFATT。试验结果表明,步冷试验之后,母材发生较低程度脆化或脱脆现象,但是脆化度或脱脆度较低,表明母材具有良好的抗回火脆化性能;经脱脆试验后,母材和焊缝都发生较高程度的脱脆,表明材料的脆化主要是由于回火脆化引起的,脱脆试验使得材料的韧脆转变温度降低;脱脆步冷试验后,焊缝发生较高程度的脆化,焊缝对脱脆步冷试验的敏感性较高,脱脆步冷试验有效促进了焊缝的脆化。在相同脆化条件下,母材的脆化敏感性低于焊缝,焊缝更易发生脆化。     

β-Cypermethrin Alleviated the Inhibitory Effect of Medium from RAW 264.7 Cells on 3T3-L1 Cell Maturation into Adipocytes

Studies have elucidated that pyrethroids induce adipogenesis. It is also known that macrophages can affect the homeostasis of adipose tissue. However, whether and how the β-cypermethrin (β-CYP)-mediated inhibition of the macrophages affects adipogenesis remain unknown. To explore the effects of β-CYP on adipogenesis through modulating the function of macrophages, 3T3-L1 cells, a preadipocyte cell line, were exposed to culture medium from either RAW 264.7 cells, a macrophage cell line (RM), or β-CYP-treated RAW 264.7 cells (CRM). CRM decreased the inhibitory effects of RM treatment on cell proliferation and adipogenesis, as lipid accumulation, the CEBPA content, and Fasn and Acaca expression in 3T3-L1 cells were higher following CRM treatment than following RM treatment through the higher levels of the demethylated CEBPA promoter in 3T3-L1 cells. However, the medium from β-CYP- and N-acetyl-L-cysteine-cotreated RAW 264.7 cells (CNRM) partially restored the inhibitory effects of RAW 264.7 cells on 3T3-L1 cells that had been reduced by CRM, indicating that β-CYP might reduce the cytotoxicity and inhibitory effects of RAW 264.7 cells on the adipogenesis of 3T3-L1 cells through elevating ROS levels in RAW 264.7 cells. Moreover, exposure to β-CYP downregulated the TNF-α secretion in RAW 264.7 cells. In conclusion, these data demonstrated that β-CYP affected the function of RAW 264.7 cells, alleviating their inhibitory effects on adipogenesis and CEBPA demethylation in 3T3-L1 cells. β-CYP might achieve these effects through downregulating the secretion of TNF-α via elevating ROS levels in RAW 264.7 cells. Our experiments provide a new perspective on the obesogenic effect of pyrethroids.     

柔性钙钛矿太阳能电池的制备及性能研究

采用钛箔作为衬底,原位生长二氧化钛薄膜,然后制备有机钙钛矿吸收层及固态空穴传输层,组装成太阳能电池。通过电压-电流曲线测试,结果表明,这种钙钛矿太阳能电池的光生电压达到0.8 V、光生电流达到16 mA/cm²、光电转化效率为10.2%。进一步对电池进行弯折试验,弯折20次后,光电转化效率能达到初始值的85%,表现出良好的柔性特征。     

Investigation of the energy-size reduction and mineral liberation of raw coal in the Hardgrove mill

Raw coal was ground in a Hardgrove mill, and mineral liberation from coal was investigated by float-sink test and electron probe microanalyzer (EPMA). Based on EPMA, associated conditions of mineral were determined. Analyses of energy-size reduction show that energy efficiency decreases with time. For +0.074 mm progenies, yields of particles in ?1.5 g.cm^?3 decrease with the increase of size and time, and products in +1.8 g.cm^?3 show the opposite trend. EPMA of 0.25–0.125 mm, 1.5–1.8 g.cm^?3 products ground for 10 min indicates that only part of minerals are liberated. For ?0.074 mm products, the yield of particles in ?1.5 g.cm^?3 decreases by 23.36% in last several minutes, but ash content of +1.8 g.cm^?3 also decreases by 13.18%. Since breakage of raw coal in last 9 min does not reduce particle size obviously, and liberation degree cannot be improved dramatically, closed grinding of 10 min in Hardgrove mill is proper to balance the size reduction and mineral liberation.     

Effect of different quenching processes following solid-solution treatment on properties and precipitation behaviors of 7050 alloy

The effects of quenching in different ways following solid-solution treatment on properties and precipitation behaviors of 7050 alloy were investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), selected area electron diffraction (SAED), hardness and electrical conductivity tests. Results show that after quenching in different ways, electrical conductivity of the alloy decreases rapidly in the first 48 h of natural aging. The electrical conductivity of 7050 alloy in natural aging state is determined by the size and density of GP zones, and the size of GP zones is the main factor. After natural aging for 70 d, the size of GP zones is 1.8–2.6 nm in matrix of the immersion quenched sample and it is 1.4–1.8 nm in matrix of both water mist and forced air quenched samples. After natural and artificial peak aging, the hardness of the water mist quenched sample is HV 193.6 and its electrical conductivity is 30.5% (IACS) which are both higher than those of the immersion quenched sample. Therefore, water mist quenching is an ideal quenching method for 7050 alloy sheets after solid-solution treatment.     

Selective hydrogenation of acetylene over Pd/CeO2

Five hundred ppm Pd/CeO₂ catalyst was prepared and evaluated in selective hydrogenation of acetylene in large excess of ethylene since ceria has been recently found to be a reasonable stand-alone catalyst for this reaction. Pd/CeO₂ catalyst could be activated in situ by the feed gas during reactions and the catalyst without reduction showed much better ethylene selectivity than the reduced one in the high temperature range due to the formation of oxygen vacancies by reduction. Excellent ethylene selectivity of ~100% was obtained in the whole reaction temperature range of 50°C–200°C for samples calcined at temperatures of 600°C and 800°C. This could be ascribed to the formation of Pd_xCe_1−xO_2−y or Pd-O-Ce surface species based on the X-ray diffraction and X-ray photoelectron spectroscopy results, indicating the strong interaction between palladium and ceria.