Non-metal boron atoms on CuB12 monolayer as efficient catalytic sites for urea production

Electrocatalytic C-N coupling reaction to convert CO2 and N2 into urea under mild conditions has been proposed to be a promising alternative experimentally, but the development of high-stable, low-cost and...

INVESTIGATION OF THE PROCESS OF PROCESSING LIQUID WASTE OF UREA PRODUCTION USING A BIOFILTER

The kinetic regularities of the recycling process of liquid waste of urea on the combined filter which contains the immobilized layer of enzymes at the process of their purification from the suspended substances, dissolved nitrate anions; the effect of pH on the filtration process are investigated and established in our research. A stable positive result was obtained on the filters with layers of: – oak and birch, the concentration of nitrate anions decreased from 12 to 0,06 — 0,05 mg/dm3 after 80 minutes of filtration. The content of suspended solids decreased from 37 g/dm3 to 6 — 7 g/dm3. At the same time, the increased content of tannins and the natural structure of oak and birch leaves contributes to the resistance of the leaf layer to fermentation processes, helps to use such kind of filter repeatedly. – linden and maple leaves, the concentration of nitrate anions decreased from 12 mg/dm3 to 0,08 mg/dm3 after 80 minutes of filtration. The content of suspended solids decreased from 37 g/dm3 to 15 g/dm3 after the third use of the filter, due to increased activity of microorganisms. At the same time, the natural structure of linden and maple leaves is thin, has a biofilm that is easily destroyed and accelerates the process of natural aerobic fermentation. The scientific substantiation of the direction of improvement of technology of processing of liquid waste with the increased content of nitrogen is executed. A bio filtration unit on a combined filter with a layer of oak and birch leaves with the use of an immobilized layer of enzymes is proposed. The combined filter consists of a layer of gravel, sand and dry oak and/or birch leaves. The enzyme Chymotrypsin at a concentration of 0,005 g/dm3 is fed into the formed bio filter from above. After 30 minutes, liquid waste with a temperature of 10 25 °С is gradually fed into the filter over 60 — 80 minutes. The initial concentration of suspended particles in liquid waste should not exceed a concentration of 37 — 40 g/dm3. It is determined that the optimal rate of processing of liquid waste of urea production is achieved in solutions with active reaction of hydrogen ions in the range of 6,5—7,3.

Regulation of Ethyl Carbamate of Saccharomyces cerevisiae in Chinese Luzhou-Flavor Liquor Fermentation

The carcinogen ethyl carbamate (EC) in alcoholic beverages mainly comes from the spontaneous reaction of ethanol and urea, and urea is produced by the breakdown of arginine by arginase in Saccharomyces cerevisiae. Regulating activity of arginase and decreasing urea content are beneficial to reduce EC in liquor. In this study, Saccharomyces cerevisiae isolated from Daqu was fermented under a series of stress conditions to evaluate the content changes of EC and its precursors. Temperature and pH below 25 °C and pH 4.0, ethanol concentration of 4–6% and a certain initial salt concentration could reduce arginine consumption and urea production by decreasing transcription level of arginase and increasing transcription level of urea carboxylase, and eventually lead to the reduction of EC. These methods will help to improve the strategy of EC control in Chinese liquor.

PENENTUAN TINGKAT EFISIENSI ALOKATIF DAN EFISIENSI TEKNIS PADA USAHATANI JAGUNG MANIS ( Zea mays saccharata L. ) DI KECAMATAN KUPANG TIMUR

Research about the determining of allocative and technical efficiency level of sweet corn farming in East Kupang Sub District aims to find out the effect of the use of production factors toward sweet corn production; to analyze the level of allocative efficiency of its use; and to analyze the level of production technical efficiency of sweet corn. The research location was chosen by purposive sampling with the consideration that Oesao village and Pukdale are villages where produce sweet corn in East Kupang Sub District. The sample of research respondents was taken by simple random sampling with 79 respondents consisting of 35 farmers from Oesao village and 44 farmers from Pukdale village. The collect of data had been carried out as long as February to March 2020. The reseach results showed that the factors of land, seed, and urea production significantly affected the production of sweet corn, while the factors of NPK, pesticides and labor production had no significant effect. The level of efficiency can be reached through allocate production inputs precisely. In this case, by reducing the use of land and urea fertilizer, on the other hand, by adding the use of seeds. Also, the farmer production level technically is not efficient yet with the average of actual production level is 10,408 grains or around 1,487 kg, while the average frontier production level is 28,146.64 grains or around 4,021 kg. There are 39 farmers who their technical efficiency in low level category, than, 28 farmers in moderate level category, and as many as 12 farmers have reached a level of technical efficiency.