CPSF30-L-mediated recognition of mRNA m^(6)A modification controls alternative polyadenylation of nitrate signaling-related gene transcripts in Arabidopsis

N6-methyladenosine(m^(6)A),a ubiquitous internal modification of eukaryotic mRNAs,plays a vital role in almost every aspect of mRNA metabolism.However,there is little evidence documenting the role of m^(6)A in regulating alternative polyadenylation(APA)in plants.APA is controlled by a large protein-RNA complex with many components,including CLEAVAGE AND POLYADENYLATION SPECIFICITY FACTOR30(CPSF30).In Arabidopsis,CPSF30 has two isoforms and the longer isoform(CPSF30-L)contains a YT512-B Homology(YTH)domain,which is unique to plants.In this study,we showed that CPSF30-L YTH domain binds to m^(6)A in v itro.In the cpsf30-2 mutant,the transcripts of many genes including several important nitrate signaling-related genes had shifts in polyadenylation sites that were correlated with m^(6)A peaks,indicating that these gene transcripts carrying m^(6)A tend to be regulated by APA.Wild-type CPSF30-L could rescue the defects in APA and nitrate metabolism in cpsf30-2,but m^(6)A-binding-defective mutants of CPSF30-L could not.Taken together,our results demonstrated that m^(6)A modification regulates APA in Arabidops is and revealed that the m^(6)A reader CPSF30-L affects nitrate signaling by controlling APA,shedding new light on the roles of the m^(6)A modification during RNA 3-end processing in nitrate metabolism.

Grain size effect on wear resistance of WC-Co cemented carbides under different tribological conditions

The grain-size dependence of wear resistance of WC-Co cemented carbides(with mean WC grain sizes of 2.2μm,1.6μm,0.8μm and 0.4μm,respectively)was investigated under different tribological conditions.The results showed that the grain size had opposite effects on wear resistance of the cemented carbides in dry sliding wear and microabrasion tests.In the former condition,with decrease of WC grain size hence the increase of hardness,plastic deformation,fracture,fragmentation and oxidation were all mitigated,leading to a drastic decrease in the wear rate.In the latter condition,pull-out of WC grains after Co removal dominated the wear,so that the hardness of cemented carbide was not a core factor.As a result,the wear resistance of the cemented carbide generally showed a decreasing trend with decrease of the grain size,except for a slight increase in the ultrafine-grained cemented carbide.Single-pass scratching of the cemented carbides under various loads indicated the same failure mechanism as that in the sliding wear tests.Furthermore,the reasons for severe surface oxidation of the coarse-grained cemented carbides were disclosed.

Development of manufacturing technology on WC-Co hardmetals

Hardmetals are tungsten carbide(WC)-based composites,which are made of WC as a hard phase and transition metals such as Co,Fe,or/and Ni as ductile binder matrices.Their properties can be mainly tailored through the grain sizes of the sintered carbides and the amount of metallic binder.As successful tool materials,hardmetals are widely applied in metal cutting,wear applications,chipless forming,stoneworking,wood,and plastic working.In 2017,about two-thirds of tungsten consumption(including recycled materials)were produced for hardmetals in the world.This paper briefly introduces the development of manufacturing technology on WC-Co hardmetals from three aspects:powder preparation,bulk densifica-tion,and performance characterization.Two special WC-Co hardmetals are also described:cobalt-enrichment zone(CEZ)hardmetals,and binderless hardmetals.Furthermore,the development prospects for manufacturing techniques of hardmetals are also presented in the end.

Atomistic observation of in situ fractured surfaces at a V-doped WC–Co interface

1.Introduction Cemented carbides are composites of WC ceramic phases and metallic Co binders that endow them with superior hardness and excellent toughness.Hard metals are widely used as metal cutting and rock drilling tools[1,2].Their hardness is believed to be inversely proportional to the sizes of WC grains^([3]).Grain growth inhibitors are widely employed to achieve smaller grain sizes.