Copper–iron mixed oxide catalyst precursors prepared by glycine-nitrate combustion method for ammonia borane dehydrogenation processes

The influence of the properties of copper ferrite, prepared by the combustion method from glycine-nitrate precursor, on the kinetics of NH₃BH₃ hydrolysis, thermolysis and hydrothermolysis are presented. As-prepared and annealed samples were studied by X-ray diffraction, scanning electron microscopy, differential dissolution, and attenuated total reflection infrared spectroscopy. It has been shown that in the hydrolysis and hydrothermolysis of NH₃BH₃, the as-prepared combustion product, which mainly consisted of a cubic spinel Cu_0.67Fe_2.33O₄ with Fe²⁺ higher content, had the highest activity, as compared with oxides of copper and iron and the annealed samples. According to transmission electron microscopy and X-ray diffraction, in the reaction medium copper ferrite is reduced to nanosized Cu⁰ and Fe⁰. This allowed the average rate of H₂ evolution per 1 g of the composition to be increased from 30 to 76 ml⋅min⁻¹, as compared with non-catalytic process. The high gravimetric hydrogen capacity (7.3 wt%) was observed at 90 °C.     

建宁莲子中二氧化硫检测及污染情况分析

目的检测建宁及其周边地区出产的52批莲子中二氧化硫残留量,以了解莲子加工过程中二氧化硫污染情况。方法采用半自动凯氏定氮仪建立莲子中二氧化硫残留量的检测方法。莲子样品经凯氏定氮仪酸化、蒸馏,蒸馏物用乙酸铅溶液吸收,吸收后的溶液用盐酸酸化,碘标准溶液滴定,根据所消耗的碘标准溶液量计算出样品中的二氧化硫含量。结果经统计学方法验证,该方法与GB 5009.34-2016中的玻璃蒸馏法测定的结果无显著性差异(P0.05);对于0.254、0.507、1.014 g/kg水平添加回收率范围在71.9%～93.5%之间;相对标准偏差范围在4.4%～7.8%。应用该方法对建宁及其周边地区出产的52批莲子进行二氧化硫污染检测分析,有7批样品不同程度检出二氧化硫,最高的83mg/kg,超过了50mg/kg的标准限量,最低的19mg/kg。结论建宁莲子中二氧化硫总体污染水平不高,但仍存在个别超标现象。     

Proteomic and high-throughput analysis of protein expression and microbial diversity of microbes from 30- and 300-year pit muds of Chinese Luzhou-flavor liquor

Luzhou-flavor liquor is fermented based on the metabolism of special microbial communities in pit. In this study, total proteins and DNAs of microbes from 30- and 300-year pit muds were firstly extracted. Meanwhile, an efficient approach for protein extraction with increased protein content was optimized. iTRAQ-based proteomic was then applied to investigate the aroma-forming functional protein expression of microbes from the samples. Furthermore, high-throughput sequencing of 16S rDNA was employed to reveal microbial diversity. We comparatively identified 63 proteins of aroma-forming functional microbes in these samples, and found that 59 of these proteins were highly expressed in the 300-year pit mud. Those aroma-forming functional proteins were found to be involved in methanogenesis, as well as the formation of caproic acid and butyric acid during the liquor fermentation. High-throughput sequencing revealed that the microbes most commonly found in both samples were members of phylum Firmicutes (by 97% sequence similarity), both of which, along with another common Methanobacterium, were important components of aroma-forming functional colonies in the pit muds for the brewing of Chinese liquor. The findings in this study afford us new insight into the different protein expression levels and microbial communities in two pit muds.