鲜白酒糟提取液对Q235钢硫酸酸洗的缓蚀性能

为了综合利用白酒糟和开发新型绿色酸洗缓蚀剂,制取了鲜白酒糟提取液,采用失重法和电化学法研究了其作为硫酸酸洗缓蚀剂的缓蚀性能。结果表明：15g酒糟在300mL5％硫酸溶液中30℃静置浸泡6h,得到的提取液在5％硫酸介质中对Q235钢的缓蚀率最高;酒糟提取液在Q235钢表面的吸附符合E1-Awady动力学模型和Flory-Huggins吸附等温方程,属于几何覆盖效应的单分子层吸附,提取液为混合型缓蚀剂;放置时间延长时,提取液的缓蚀率降低。     

Fabrication of porous (Ba,Sr)(Co,Fe)O3-δ (BSCF) ceramics using gelatinization and retrogradation phenomena of starch as pore-forming agent

Porous (Ba,Sr)(Co,Fe)O_3-δ (BSCF) ceramics with high open porosity and good electrical conductivity was fabricated using Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF), which shows a high mixed ionic-electronic conductivity. In general, during the fabrication of porous ceramics by the sacrificial template method using pore former particles, closed pores are easily formed unless sufficient pore former particles are added. In this study, we have devised a method using the gelatinization-retrogradation phenomena of starch for producing a porous body with an excellent percolated pore network structure. By dispersing BSCF and starch in an aqueous slurry (0–50% by weight) and heating, gelatinization of the starch occurred and the starch particles adhered to each other. Furthermore, in order to retain the percolated structure, the water solvent was removed by freeze-drying without heating to obtain a dried green body. The sintering behavior of the porous BSCF bodies prepared under various conditions was characterized by microstructural observations and relative density measurements. By optimizing the process conditions of the gelatinization and retrogradation, a porous body having an open porosity of 48.3%, and with 99% of the total pores open, was obtained. The matrix was also well connected and showed a sufficiently high conductivity which was similar to the porous bodies made by the traditional sacrificial template method.     

Effect of initial solution apparent pH on nano-sized nickel catalysts in p-nitrophenol hydrogenation

The effect of initial solution apparent pH (pH_a) on nano-sized nickel in the catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated in detail. Experimental results show that the catalytic activity of the nano-sized nickel shows a strong dependence on the initial solution pH_a, and is the highest at the initial solution pH_a 4.8. At lower or higher pH_a values the nano-sized nickel will obviously deactivate, but the deactivation mechanisms are fully different. With respect to the former, the nickel dissolution and the strong adsorption of the complex compound of nickel ion and p-nitrophenol on the surface of nano-sized nickel are the main reasons. The severe agglomeration of nickel particles also causes the deactivation of nickel used at the initial solution pH_a 1.6. For the latter the main reasons are the formation of nickel hydroxide surface species and the decrease of p-nitrophenol adsorption on the hydrogenation sites.     

分子印迹技术在天然药物有效成分提取分离中的应用

简绍了分子印迹技术原理、分子印迹聚合物制备方法,对分子印述技术在天然药物分离纯化中的手性分离、固相萃取、膜分离方法等应用进行评述,分析了现有分子印迹技术存在的问题,展望了分子印迹技术在天然药物提取分离中的应用前景.     

Effects of YH2 addition on pressureless sintered AlN ceramics

A new type of non-oxide sintering additive of YH₂ was introduced for the fabrication of AlN ceramics with high thermal conductivity and flexural strength. The effects of YH₂ addition (0–5 wt%) on the phase composition, densification, microstructure, thermal conductivity and flexural strength of pressureless sintered AlN ceramics were investigated and compared with those Y₂O₃-added samples (1–5 wt%). The addition of 1 wt% YH₂ led to an in-situ reduction reaction with oxygen impurities, the formation of Y₂O₃ and finally the formation of yttrium aluminate, which in turn improved densification and microstructure. A high flexural strength (408.69 ± 28.23 MPa) was achieved. The addition of 3 wt% YH₂ increased the average grain size and purified the lattice. All these effects are believed to help achieve a high thermal conductivity of 184.82 ± 1.75 W·m^?1·K^?1. Although the thermal conductivity was close to the value of 3 wt% Y₂O₃-added sample, its strength was much increased to 381.53 ± 43.41 MPa. Meanwhile, it demonstrated a good combination of the thermal conductivity and flexural strength than the values reported in some literature. However, further increasing the YH₂ addition to 5 wt% resulted in a high N/O ratio that inhibited the densification behavior of AlN ceramics. The current study showed that AlN ceramics with excellent thermal and mechanical properties could be obtained by the introduction of a suitable YH₂ additive.