Synthesis of active, robust and cationic Au25 cluster catalysts on double metal hydroxide by long-term oxidative aging of Au25(SR)18

Synthesis of an atomically precise Au25 cluster catalyst was attempted by long-term, low-temperature pretreatment of Au25(BaET)18 (BaET-H = 2-(Boc-amino)ethanethiol) on various double metal hydroxide (DMH) supports. X-ray absorption fine structure...

Bulb Dormancy In Vitro—Fritillaria meleagris: Initiation, Release and Physiological Parameters

In ornamental geophytes, conventional vegetative propagation is not economically feasible due to very slow development and ineffective methods. It can take several years until a new plant is formed and commercial profitability is achieved. Therefore, micropropagation techniques have been developed to increase the multiplication rate and thus shorten the multiplication and regeneration period. The majority of these techniques rely on the formation of new bulbs and their sprouting. Dormancy is one of the main limiting factors to speed up multiplication in vitro. Bulbous species have a period of bulb dormancy which enables them to survive unfavorable natural conditions. Bulbs grown in vitro also exhibit dormancy, which has to be overcome in order to allow sprouting of bulbs in the next vegetation period. During the period of dormancy, numerous physiological processes occur, many of which have not been elucidated yet. Understanding the process of dormancy will allow us to speed up and improve breeding of geophytes and thereby achieve economic profitability, which is very important for horticulture. This review focuses on recent findings in the area of bulb dormancy initiation and release in fritillaries, with particular emphasis on the effect of plant growth regulators and low-temperature pretreatment on dormancy release in relation to induction of antioxidative enzymes’ activity in vitro.

The effect of Sibunit graphitization on the stability of Ru/(Pt, Pd)/Sibunit catalysts in an oxidizing atmosphere at elevated temperatures

The effect of high-temperature treatment on the thermal stability of a graphitic carbon material Sibunit in an oxidizing medium was studied in dependence on the presence of active component – Pt, Pd or Ru. According to thermal analysis data, a high-temperature pretreatment of Sibunit increases the onset temperature of carbon oxidation. It was found that holding of the Ru/Sibunit samples for 4 h in a nitrogen: air (1 : 1) mixture at a temperature of 400 °С resulted in a partial destruction of the pyrocarbon matrix of Sibunit and increased the mean size of Ru particles. It was demonstrated that ruthenium catalysts can efficiently oxidize CO at a temperature not higher than 200 °С and withstand overheats up to 400 °С without a significant loss in activity.

OPTIMIZING THE EFFECT OF CHEMICAL PRETREATMENT ON LIGNOCELLULOSIC PROPERTIES OF WHEAT STRAW

The current research was postured for optimizing the pretreatment of wheat straw with three different chemicals i.e., 1% NaOH at 121°C for 1 hour, 4% lime at 80°C for 40 minutes, similarly 4% acetic acid at 121°C for 1 hour and studying their effect on lingo cellulosic structure of wheat straw. It was observed that NaOH treatment was most suitable maximum degradation of lignin and least disruption of cellulosic contents. NaOH pretreatment was optimized for three main process parameters i.e., temperature, pretreatment time and chemical concentration. It was analyzed that at same concentration by varying treatment time and temperature, hemicelluloses and lignin contents decreased with the increase of both parameters. Concentration of chemical was optimized at boiling temperature of 105°C for 10 minutes, revealed that with the increase in NaOH concentration lignin and hemicelluloses contents degrade more. Time parameter was optimized applying treatment of 2, 5 and 8 days. Lignin degradation was highest at 8% NaOH concentration for 2 days. Lignin contents increased abruptly at 8% NaOH and 8 days of treatment. Optimum conditions obtained for cellulose and hemicellulose are 2% NaOH, 105°C for 10 minutes.