Ultra‐small metal nanoclusters have high surface energy and abundant active sites,and thereforetheir catalytic activities are usually significantly higher than those of larger nanoparticles.A temperature‐responsive ...Ultra‐small metal nanoclusters have high surface energy and abundant active sites,and thereforetheir catalytic activities are usually significantly higher than those of larger nanoparticles.A temperature‐responsive copolymer,namely poly(ethylene glycol)‐co‐poly(N‐isopropylacrylamide)(PEG‐PNIPAM)was synthesized as the first step,and then ultra‐small Pd clusters stabilized withinPEG‐PNIPAM copolymer micelles were formed by direct reduction.Pd nanoclusters of size less than2nm showed outstanding catalytic activity in the Suzuki coupling reaction.The reaction betweeniodobenzene and phenylboronic acid was completed in as little as10s(turnover frequency=4.3×104h?1).A yield of64%was achieved in5min in the reaction between chlorobenzene and phenylboronicacid.The catalyst showed significant deactivation during three consecutive runs.However,this composite catalyst consisting of Pd/PEG‐PNIPAM can be easily recycled based on the reversiblephase transition of temperature‐responsive PEG‐PNIPAM.This catalyst therefore has good potentialfor practical applications.展开更多
Application of improper methods on rice processing affects rice quality and head rice recovery. In Vietnam, paddy with different moisture contents (from 13% to 17%) is dehusked by both rubber roll and stone disk. Th...Application of improper methods on rice processing affects rice quality and head rice recovery. In Vietnam, paddy with different moisture contents (from 13% to 17%) is dehusked by both rubber roll and stone disk. Thus, objective of this research was to evaluate the technical and economic aspects of the two methods. Optimization was conducted with 20 experiments for input factors (moisture content) and output factors (head brown rice recovery, specific energy consumption). Besides, other factors were also monitored, such as the gap between the two disks, speed of disk and roll, and pressure of rubber roll on paddy. Test results showed that the maximum value of head brown rice (77.4%) and the minimum value of specific energy consumption (0.66 kWh/ton) corresponding to moisture content of paddy of 13.7% for stone disk dehusker. At similar moisture content (13.7%), head brown rice recovery and specific energy consumption were 77.2% and 1.04 kWh/ton for rubber roll dehusker, respectively. As the result, specific energy consumption of rubber roll dehusker was higher than that of stone disk dehusker, corresponding to the higher dehusking efficiency.展开更多
基金supported by the National Natural Science Foundation of China (51502089,51302008)the Fundamental Research Funds for the Central Universities (2016MS03)~~
文摘Ultra‐small metal nanoclusters have high surface energy and abundant active sites,and thereforetheir catalytic activities are usually significantly higher than those of larger nanoparticles.A temperature‐responsive copolymer,namely poly(ethylene glycol)‐co‐poly(N‐isopropylacrylamide)(PEG‐PNIPAM)was synthesized as the first step,and then ultra‐small Pd clusters stabilized withinPEG‐PNIPAM copolymer micelles were formed by direct reduction.Pd nanoclusters of size less than2nm showed outstanding catalytic activity in the Suzuki coupling reaction.The reaction betweeniodobenzene and phenylboronic acid was completed in as little as10s(turnover frequency=4.3×104h?1).A yield of64%was achieved in5min in the reaction between chlorobenzene and phenylboronicacid.The catalyst showed significant deactivation during three consecutive runs.However,this composite catalyst consisting of Pd/PEG‐PNIPAM can be easily recycled based on the reversiblephase transition of temperature‐responsive PEG‐PNIPAM.This catalyst therefore has good potentialfor practical applications.
文摘Application of improper methods on rice processing affects rice quality and head rice recovery. In Vietnam, paddy with different moisture contents (from 13% to 17%) is dehusked by both rubber roll and stone disk. Thus, objective of this research was to evaluate the technical and economic aspects of the two methods. Optimization was conducted with 20 experiments for input factors (moisture content) and output factors (head brown rice recovery, specific energy consumption). Besides, other factors were also monitored, such as the gap between the two disks, speed of disk and roll, and pressure of rubber roll on paddy. Test results showed that the maximum value of head brown rice (77.4%) and the minimum value of specific energy consumption (0.66 kWh/ton) corresponding to moisture content of paddy of 13.7% for stone disk dehusker. At similar moisture content (13.7%), head brown rice recovery and specific energy consumption were 77.2% and 1.04 kWh/ton for rubber roll dehusker, respectively. As the result, specific energy consumption of rubber roll dehusker was higher than that of stone disk dehusker, corresponding to the higher dehusking efficiency.