Effects of thermal activation conditions on the microstructure regulation of corncob-derived activated carbon for hydrogen storage

Activated carbons derived from corncob （CACs） were prepared by pyrolysis carbonization and KOH activation. Through modifying activation conditions, samples with large pore volume and ultrahigh BET specific surface area could be obtained. The sample achieved the highest hydrogen uptake capacity of 5.80 wt% at 40 bar and -196℃ The as-obtained samples were characterized by N2-sorption, transmission electron microscopy （TEM） and scanning electron microscopy （SEM）. Besides, thermogravimetric analysis was also employed to investigate the activation behavior of CACs. Detailed investigation on the activation parameters reveals that moderate activation temperature and heating rate are favorable for preparing CACs with high surface area, large pore volume and optimal pore size distribution. Meanwhile, the micropore volume between 0.65 nm and 0.85 nm along with BET surface area and total pore volume has great effects on hydrogen uptake capacities. The present results indicate that CACs are the most promising materials for hydrogen storage application.

Rice OsUBR7 modulates plant height by regulating histone H2B monoubiquitination and cell proliferation

Plant height is an important agronomic trait for lodging resistance and yield.Here,we report a new plantheight-related gene,OsUBR7 in rice(Oryza sativa L.);knockout of OsUBR7 caused fewer cells in internodes,resulting in a semi-dwarf phenotype.OsUBR7 encodes a putative E3 ligase containing a plant homeodomain finger and a ubiquitin protein ligase E3 component N-recognin 7(UBR7)domain.OsUBR7 interacts with histones and monoubiquitinates H2B(H2Bub1)at lysine148 in coordination with the E2 conjugase OsUBC18.OsUBR7 mediates H2Bub1 at a number of chromatin loci for the normal expression of target genes,including cell-cycle-related and pleiotropic genes,consistent with the observation that cell-cycle progression was suppressed in the osubr7 mutant owing to reductions in H2Bub1 and expression levels at these loci.The genetic divergence of OsUBR7 alleles among japonica and indica cultivars affects their transcriptional activity,and these alleles may have undergone selection during rice domestication.Overall,our results reveal a novel mechanism that mediates H2Bub1 in plants,and UBR7 orthologs could be utilized as an untapped epigenetic resource for crop improvement.