Unveiling the importance of reactant mass transfer in environmental catalysis: Taking catalytic chlorobenzene oxidation as an example

To date, investigations onto the regulation of reactants mass transfer has been paid much less attention in environmental catalysis. Herein, we demonstrated that by rationally designing the adsorption sites of multi-reactants, the pollutant destruction efficiency, product selectivity, reaction stability and secondary pollution have been all affected in the catalytic chlorobenzene oxidation (CBCO). Experimental results revealed that the co-adsorption of chlorobenzene (CB) and gaseous O₂ at the oxygen vacancies of CeO₂ led to remarkably high CO₂ generation, owning to their short mass transfer distance on the catalyst surface, while their separated adsorptions at Brönsted HZSM-5 and CeO₂ vacancies resulted in a much lower CO₂ generation, and produced significant polychlorinated byproducts in the off-gas. However, this separated adsorption model yielded superior long-term stability for the CeO₂/HZSM-5 catalyst, owning to the protection of CeO₂ oxygen vacancies from Cl poisoning by the preferential adsorption of CB on the Brönsted acidic sites. This work unveils that design of environmental catalysts needs to consider both of the catalyst intrinsic property and reactant mass transfer; investigations of the latter could pave a new way for the development of highly efficient catalysts towards environmental pollution control.     

Plasmonic sensing of CTAB in gold nanorods solution based on Cu(II) ions-mediated H2O2 etching effect

Controlled release formulation of pesticides is highly desirable for attaining the most effective utilization of the pesticide as well as reducing environmental pollution. Nano-sized controlled release formulations can provide better penetration through cuticle and deliver the active ingredients efficiently to the targeted tissue. In this study, a novel strategy for the preparation of a nanoconjugate derived from kasugamycin with amino-modified silica was developed. The kasugamycin was connected with amino-modified silica matrix by an amide bond, which could avoid the initial burst release effectively and prolong the duration remarkably. The results showed the kasuga-silica can protect kasugamycin against photo-degradation effectively and the release rate of the active ingredient of nanoconjugate was related to the temperature, pH value, and the particle size (52.5–315.4 nm). With reduced particle size as well as increased temperature and acidity, the release of the active ingredient was faster. This amide linkage of kasuga-silica could be degraded by amidase effectively. This nanoconjugate displayed a better and a sustained bactericidal efficacy against E. coli than kasugamycin technical, which makes it a potential candidate as a controlled release conjugate for kasugamycin in the future.     

Failure Processes in Fiber-Reinforced Liquid-Crystalline Polyester Composites

A hierarchical structural model for liquid-crystalline polyester reinforced with short glass fibers has been determined by using injection-molded bars. The gradient structure showed similar orientations between the glass fibers and the molecular orientation of the matrix. In the fiber-reinforced composites, the core failed prior to the skin by matrix cracking and transverse fiber pull-out as evidenced by the initial growth of parabolic cracks in the core. In the 30 wt% composite this was followed by complex cooperative phenomena involving fiber breakage, debonding, pull-out, and matrix deformation in the skin. The 50 wt% composite failed prematurely due to inadequate fiber/matrix interactions in the skin structure. Acoustic emission coupled with microscopy provided mechanistic insight throughout this work into the amount and intensity of specific failure mechanisms.     

高效液相色谱法测定榨菜中柠檬黄的不确定度评定

根据JJF1059～1999《测量不确定度评定与表示》对高效液相色谱法测定榨菜中柠檬黄含量的测定不确定度进行评定。通过对实验过程中样品的取样称量、使用仪器、标准物质、测试过程中的随机因素以及标准工作曲线的拟合等因素进行分析,计算了不确定度分量和合成不确定度。榨菜中柠檬黄含量的测定结果为（0．0375±0．0050）g／kg,k=2。