Mass transfer in gas–liquid stirred reactor with various triple-impeller combinations

The gassed power demand and volumetric mass transfer coefficient （kca） were investigated in a fully baffled, dished-base stirred vessel with a diameter of 0.30 m agitated by five triple-impeller combinations. Six types of impellers （six-half-elliptical-blade disk turbine （HEDT）, four-wide-blade hydrofoil impeller （WH） pumping down （D） and pumping up （U）, parabolic-blade disk turbine （PDT）, and CBY narrow blade （N） and wide blade （W）） were used to form five combinations identified by PDT ＋ 2CBYN, PDT ＋ 2CBYw, PDT ＋ 2WHD, HEDT ＋ 2WHD and HEDT ＋ 2WHo, respectively. The results show that the relative power demand of HEDT ＋ 2WHu is higher than that of other four impeller combinations under all operating conditions. At low superficial gas velocity （uc）, kLa differences among impeller combinations are not obvious. However when UG iS high, PDT ＋ 2WHD shows the best mass transfer performance and HEDT ＋ 2WHu shows the worst mass trans- fer performance under all operating conditions. At high uc and a given power input, the impeller combinations with high agitation speed and big projection cross-sectional area lead to relatively high values of kLa. Based on the experimental data, the regressed correlations of gassed power number with Froude number and gas flow number, and kLa with power consumption and superficial gas velocity are obtained for five different impeller combinations, which could be used as guidance for industrial design.

Establishment of new convenient two-line system for hybrid production by targeting mutation of OPR3 in allopolyploid Brassica napus

The two-line pollination control system,which usually depends on the utilization of thermosensitive or photoperiod genic male-sterile lines,has been widely used in various crops.However,this system is susceptible to instability issues caused by uncontrollable weather fluctuations.A stable and handy two-line pollination control system is highly desirable in many crop species for heterosis exploitation.Oxophytodienoic acid reductase 3(OPR3)was proven to be involved in jasmonate biosynthesis.In the present study,CRISPR/Cas9(Clustered Regularly Interspaced Short Palindromic Repeat)was utilized to mutate two OPR3 homologs in Brassica napus.After two OPR3 homologs were simultaneously mutated,mutants exhibited complete male sterility,and fertility could be easily restored by exogenous MeJA treatment.Hybrids produced from crosses between the opr3 sterile lines and normal varieties exhibited heterosis.This new two-line system based on OPR3 mutation provides higher stability and convenience than traditional systems.By using exogenous MeJA treatment to restore fertility,the system enables more precise control of male fertility transition,which has great potential to significantly contribute to the maneuverable production of hybrid seeds in rapeseed as well as other Brassica species crops.

Configurable microcavity-enhanced graphene photothermoelectric terahertz detectors

Terahertz(THz)detectors with high sensitivity,fast response speed,room temperature operation,and self-powered feature are the key component for many THz applications.Microcavity resonators can effectively improve the sensitivity of THz detectors.However,it is difficult to precisely evaluate the microcavity resonator induced such improvement in experiment.Here,we realize a configurable microcavity–antenna-integrated graphene photothermoelectric(PTE)THz detector.Through the microcavity–antenna hybrid structure,THz radiations are localized and enhanced at one end of the graphene channel,and the temperature difference along the channel is greatly increased,resulting in the strong enhancement of PTE response.At the resonant frequency,the device has a high responsivity(976 V/W),low noise equivalent power(2.87 pW∕Hz1∕2),and fast response speed(300 ns)at room temperature and in zero-bias operation mode.The microcavity-induced peak enhancement factor of 13.14 is accurately extracted.The microcavity–antenna introduced enhancement is further confirmed by using a two-temperature heat transfer model.The strategy of using a configurable microcavity is useful for further optimizing THz detectors by introducing the critical coupling mechanism.