Gravesoil fungi are more sensitive than bacteria in response to precipitation

Precipitation scenario alteration leads to grievous ecological consequences in ecosystems,especially on the Qinghai-Tibet Plateau.Bacterial and fungal community and their abundant and rare taxa in soil ecosystems may respond differently to the changed precipitation.Therefore,more attention needs to be paid to the sensitivity of bacteria and fungi and their abundant and rare taxa to precipitation shifts.The responses of bacterial and fungal populations and their abundant and rare taxa concerning diversity,assembly,and interactions to manipulative changes of precipitation were explored via imitating no precipitation,little precipitation,and medium precipitation using 16S rRNA gene and ITS amplicon sequencing.The results indicated that the change rate of fungal Simpson diversity with precipitation was higher than that of bacteria.The slope of the modified stochasticity ratio(MST)value of fungi to precipitation was steeper than that of bacteria.The Simpson diversity and the MST value of abundant and rare taxa within bacteria had no difference with precipitation.In contrast,those of abundant taxa within fungi varied more than rare ones with precipitation.By unveiling the differential responses of microbial populations with discrepant characteristics,this study allowed us to understand the different microbial communities responding to rainfall on the Qinghai-Tibet Plateau.

Multivariate relationships between microstructure evolution and strengthening mechanisms in laser powder bed fusion of Al-Mn-Sc alloy:towards improved fatigue performance

The effects of direct aging treatment(at 300°C for 5 hours)on selective laser melted(SLMed)Al-4.5Mn-1.5Mg-0.9Sc-0.2Zr alloy were investigated in this work,with the microstructure,fatigue behaviors,and fracture characteristics examined to determine the primary cause of fatigue crack source.The results revealed that the microstructure of the investigated alloy comprised fine equiaxed and columnar grains.Upon aging treatment,a significant number of nano-scaled Al3(Sc,Zr)precipitates were dispersed within the grains,leading to a substantial increase in strengths.The yield strength improved from 431 MPa to 568 MPa,representing an increase of more than 32%,while the fatigue strength improved from 180 MPa to 220 MPa after aging treatment.Nevertheless,the fracture toughness decreased significantly from 25.1 MPa·√m to 12.3 MPa·√m.The results of the fatigue fracture characteristics indicate that the Mn-rich phase and the formation of defects such as pores and poor powder fusion are the sources of fatigue cracking.Although direct aging treatment can significantly increase the yield strength,decrease the rate of fatigue crack propagation,and thus improve the fatigue performance,it deteriorates the fracture toughness,and thus shortens the fatigue life of the alloy as well.