2D materials' membranes with well-defined nanochannels are promising for precise molecular separation. Herein, the design and engineering of atomically thin 2D MXene flacks into nanofilms with a thickness of 20 nm for gas separation are reported. Well-stacked pristine MXene nanofilms are proven to show outstanding molecular sieving property for H 2 preferential transport. Chemical tuning of the MXene nanochannels is also rationally designed for selective permeating CO 2 . Borate and polyethylenimine (PEI) molecules are well interlocked into MXene layers, realizing the delicate regulation of stacking behaviors and interlayer spacing of MXene nanosheets. The MXene nanofilms with either H 2 -or CO 2 -selective transport channels exhibit excellent gas separation performance beyond the limits for state-of-the-art membranes. The mechanisms within these nanoconfined MXene layers are discussed, revealing the transformation from "diffusion-controlled" to "solution-controlled" channels after chemical tuning. This work of precisely tailoring the 2D nanostructure may inspire the exploring of nanofluidics in 2D confined space with applications in many other fields like catalysis and energy conversion processes.fabrication. Hence, MXene is considered to be a novel potential candidate for developing separative 2D-material membranes. However, there are a very few reports on MXene separation membranes. Gogotsi and co-workers first reported MXene membranes for rejection of trivalent cation in solution using nonpressure diffusion. [12] A high water permeance was obtained by applying MXene stacks in the pressure-filtration process, [13] but the membrane can only rejected matters with a size larger than 2.5 nm. Very recently, Wang and co-workers [14] reported the manufacturing of MXene membranes with highly ordered nanochannel structures for high-performance separation of H 2 /CO 2 , which opens the door of applying MXene membranes for molecular separation. It is considered that rationally regulating the nanostructure of 2D channels may, thereby, enlighten the exploring of MXene materials for sub-nanoscale separation with versatile functionalities.Herein, we report the design and engineering of MXene nanofilms with tunable transport channels for gas separation. Ultrathin pristine MXene nanofilms with a thickness down to 20 nm were fabricated by horizontally aligning the exfoliated MXene nanosheets on porous substrates. Molecular sieving channels within pristine MXene nanofilm can be formed to show highly selective H 2 permeation, as shown in Figure 1. Interestingly, these MXene laminates, as functionalized by borate and amine, exhibit different stacking behaviors and tunable interlayer spacing, allowing preferential CO 2 permeation. The resulting separation performance of either H 2 -or CO 2selective MXene nanofilms is beyond the performance limits for state-of-the-art membranes.

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Callose is a β-l,3-glucan with diverse roles in the viral pathogenesis of plants. It is widely believed that the deposition of callose and hypersensitive reaction (HR) are critical defence responses of host plants against viral infection. However, the sequence of these two events and their resistance mechanisms are unclear. By exploiting a point inoculation approach combined with aniline blue staining, immuno-electron microscopy and external sphincters staining with tannic acid, we systematically investigated the possible roles of callose deposition during viral infection in soybean. In the incompatible combination, callose deposition at the plasmodesmata (PD) was clearly visible at the sites of inoculation but viral RNA of coat protein (CP-RNA) was not detected by RT-PCR in the leaf above the inoculated one (the upper leaf). In the compatible combination, however, callose deposition at PD was not detected at the site of infection but the viral CP-RNA was detected by RT-PCR in the upper leaf. We also found that in the incompatible combination the fluorescence due to callose formation at the inoculation point disappeared following the injection of 2-deoxy-D-glucose (DDG, an inhibitor of callose synthesis). At same time, in the incompatible combination, necrosis was observed and the viral CP-RNA was detected by RT-PCR in the upper leaf and HR characteristics were evident at the inoculation sites. These results show that, during the defensive response of soybean to viral infection, callose deposition at PD is mainly responsible for restricting the movement of the virus between cells and it occurs prior to the HR response.

The optimization of plant architecture in order to breed high-yielding soya bean cultivars is a goal of researchers. Tall plants bearing many long branches are desired, but only modest success in reaching these goals has been achieved. MicroRNA156 (miR156)-SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) gene modules play pivotal roles in controlling shoot architecture and other traits in crops like rice and wheat. However, the effects of miR156-SPL modules on soya bean architecture and yield, and the molecular mechanisms underlying these effects, remain largely unknown. In this study, we achieved substantial improvements in soya bean architecture and yield by overexpressing GmmiR156b. Transgenic plants produced significantly increased numbers of long branches, nodes and pods, and they exhibited an increased 100-seed weight, resulting in a 46%-63% increase in yield per plant. Intriguingly, GmmiR156b overexpression had no significant impact on plant height in a growth room or under field conditions; however, it increased stem thickness significantly. Our data indicate that GmmiR156b modulates these traits mainly via the direct cleavage of SPL transcripts. Moreover, we found that GmSPL9d is expressed in the shoot apical meristem and axillary meristems (AMs) of soya bean, and that GmSPL9d may regulate axillary bud formation and branching by physically interacting with the homeobox gene WUSCHEL (WUS), a central regulator of AM formation. Together, our results identify GmmiR156b as a promising target for the improvement of soya bean plant architecture and yields, and they reveal a new and conserved regulatory cascade involving miR156-SPL-WUS that will help researchers decipher the genetic basis of plant architecture.