Remarkable enhancement of gas selectivity on organosilica hybrid membranes using urea-modulated metal-organic framework nanoparticles

Metal-organic framework/organosilica hybrid membranes on tubular ceramic substrates have shown great potential for the implementation of membrane technology in practical gas separation projects due to their higher permeance compared to commercial polymers.However,the selectivities of the reported membranes are moderate.Here,we have incorporated urea-modulated metal-organic frameworks into organosilica membranes to greatly enhance its separation performance.The urea-modulated metal-organic frameworks exhibit less-defined edges of crystallographic facets and high defect density.They can be well-dispersed in the organosilica layer,which substantially suppresses the interfacial defects between metal-organic frameworks and organosilica,which is beneficial for improving the selectivity of membranes for gas separation.The results have shown that the enhanced ideal selectivity of H_(2)/CH_(4) was 165 and that of CO_(2)/CH_(4) was 43,with H_(2) permeance of about 1.25×10^(−6) mol·m^(−2)·s^(−1)·Pa^(−1) and CO_(2) permeance of 3.27×10^(−7) mol·m^(−2)·s^(−1)·Pa^(−1) at 0.2 MPa and 25℃.In conclusion,the high level of hybrid membranes can be used to separate H_(2)(or CO_(2))from the binary gas mixture H_(2)/CH_(4)(or CO_(2)/CH_(4)),which is important for gas separation in practical applications.Moreover,the simple and feasible modulation of metal-organic framework is a promising strategy to tune different metal-organic frameworks for membranes according to the actual demands.

Discrete element simulations and experiments of soil-winged subsoiler interaction

Understanding soil disturbance behaviors under the impact of the winged subsoiler is critical for designing or optimizing the winged subsoiler(a primary subsoiling tool).In this study,a soil-winged subsoiler interaction model was developed and the effects of winged subsoiler on soil disturbance behaviors were investigated using the discrete element method(DEM)simulations and lab soil-bin tests.The results showed that wings mainly affected the disturbance range and fragmentation degree of soil above them.The draught forces of share section(SS),arc section in the hardpan(ASHP),arc section in the top layer(ASTL)and line section(LS)were accounted for 69.53%,25.22%,4.73%and 0.52%of the total draught force of winged subsoiler;the lateral disturbance range from high to low of the soil at different depths followed the ranking:top layer(TL),hardpan disturbed by arc section(HDAS)and hardpan disturbed by share section(HDSS).Wings had the greatest influence on the draught force of ASHP.Adding wings to an arc-shaped subsoiler increased the disturbance areas of HDAS,TL and HDSS by 47.52%,7.74%and 4.59%,respectively,but meanwhile increased the total draught force by 36%.Compared with a non-winged subsoiler,winged subsoiler had higher soil looseness(15.83%),soil disturbance coefficient(58.59%),furrow width(448.65 mm)and soil disturbance area ratio(0.3835),but poorer soil surface flatness(19.79 mm)and lower soil loosening efficiency(39.35 mm²/N).This study provided critical information for optimizing winged subsoilers on aspects of improving soil loosening effectiveness and reducing draught force.

Lentivector-mediated RNAi efficiently downregulatesexpression of murine cdk4 gene in vitro

In order to explore the role of cyclin-dependent kinase 4(cdk4)in neurodegenerative diseases,lentiviral-delivered RNA interference(RNAi)was used to silence the expression of the murine cdk4 gene in vitro.Three cdk4-shRNAs of mouse and a negative sequence were designed.After synthesis and annealing,double strand oligonucleo-tides were cloned into a linearized pSIH1-H1-copGFP shRNA vector.It was confirmed by polymerase chain reaction(PCR)and sequencing that three pairs of cdk4-shRNAs and a negative shRNA were correctly inserted into the pSIH1-H1-copGFP vector.The above recombi-nants were transfected by lipofectamine into BV-2 cells.The gene silencing efficacy rates of the 3 targets were compared by Western blotting.The cdk4-siRNA2 was the most effective in silencing cdk4.The optimized pSIH1-cdk4-siRNA2 and pSIH-negative-siRNA were co-transfected into 293T cells with the lentiviral packaging plasmids respectively.The culture supernatant was har-vested and condensed at the 24th and 48th h after transfection.Interference efficiency of the lentivirus expressing cdk4-siRNA was determined by reverse transcriptase-PCR(RT-PCR)and Western blotting in BV-2 cells.Lentivector-mediated RNAi could efficiently down-regulate the expression of the murine cdk4 gene in vitro,which provides a potential tool for studying and treating cdk4-related diseases.