Climate factors affect forest biomass allocation by altering soil nutrient availability and leaf traits

Biomass in forests sequesters substantial amounts of carbon;although the contribution of aboveground biomass has been extensively studied, the contribution of belowground biomass remains understudied. Investigating the forest biomass allocation is crucial for understanding the impacts of global change on carbon allocation and cycling.Moreover, the question of how climate factors affect biomass allocation in natural and planted forests remains unresolved. Here, we addressed this question by collecting data from 384 planted forests and 541 natural forests in China. We evaluated the direct and indirect effects of climate factors on the belowground biomass proportion(BGBP). The average BGBP was 31.09% in natural forests and was significantly higher(38.75%) in planted forests. Furthermore, we observed a significant decrease in BGBP with increasing temperature and precipitation. Climate factors, particularly those affecting soil factors, such as p H,strongly affected the BGBP in natural and planted forests. Based on our results, we propose that future studies should consider the effects of forest type(natural or planted) and soil factors on BGBP.

High‐throughput formation of miniaturized cocultures of 2D cell monolayers and 3D cell spheroids using droplet microarray

Most of the biological processes,including cell signaling,cancer invasion,embryogenesis,or neural development,are dependent on and guided by the complex architecture and composition of cellular microenvironments.Mimicking such microenvironments in cell coculture models is crucial for fundamental and applied biology investigations.The ability to combine different cell types grown as both two‐dimensional(2D)monolayers and three‐dimensional(3D)spheroids in specific defined location inside a microculture environments is a key towards in vitro tissue modeling and towards mimicking complex in vivo cellular processes.In this study,we introduce and investigate a method to create in vitro models of 2D cell monolayers cocultured with 3D spheroids in defined preorganization.We demonstrate the possibility of creating such complex cellular microenvironments in a high‐throughput and automated manner by creating arrays of such droplets containing prearranged 2D and 3D cellular microcolonies.Furthermore,we demonstrate an application of this approach to study paracrine propagation of Wnt signaling between 2D and 3D cellular colonies.This method provides a general approach for the miniaturized,high‐throughput,and automated formation of complex coculture cellular microarchitectures that will be useful for mimicking various in vivo complex cellular structures and for studying complex biological processes in vitro.

Development of microstructural inhomogeneity in multi-pass flow forming of TA15 alloy cylindrical parts

Revealing the development of microstructural inhomogeneity in the multi-pass flow forming of titanium alloy components is of great significance to the microstructure control and property tailoring.To this end,the microstructural inhomogeneity of TA15 alloy spun cylindrical parts was analyzed based on the deformation history.The results indicate that the material underwent significant compressive strain in the normal direction(ND),tension strain in the rolling and circumferential directions(RD and CD),while tension strain in the CD is slightly small due to the limited material flow in this direction.These strain characteristics make the microstructure,especially the primary a(ap),present different morphologies in the different planes of the part.Meanwhile,the combined effects of inhomogeneous deformation and temperature distribution in the ND also cause the inhomogeneity of microstructure morphology and parameters in this direction.Quantitative analyses show that with the forming pass increasing,the aspect ratio of apincreases most in the normal-rolling plane,then in the normal-circumferential plane and least in the circumferential-rolling plane,whereas apcontent decreases in an opposite trend.Along the ND,the aspect ratio and content of apis relatively high in the outer and inner surface areas but lowest in the central area,and these inhomogeneous characteristics can be gradually diminished with the forming pass increasing.Furthermore,the variation of hardness inhomogeneity factor indicates that a four-pass forming with the total reduction ratio of 63%could obtain a homogenous microstructure along the ND of the TA15 alloy spun cylindrical part.

Analysis of anisotropy mechanism in the mechanical property of titanium alloy tube formed through hot flow forming

Anisotropy of mechanical property is an important feature influencing the service performance of titanium(Ti)alloy tube component.In this work,it is found that the hot flow formed Ti alloy tube exhibits higher yield strength along circumferential direction(CD),and larger elongation along rolling direction(RD),presenting significant anisotropy.Subsequently,the quantitative characteristics and underlying mechanism of the property anisotropy were revealed by analyzing the slip,damage and fracture behavior under the combined effects of the spun{0002}basal texture and fibrous microstructure for different loading directions.The results showed that the prismatic slip in primaryαgrain is the dominant deformation mechanism for both loading directions at the yielding stage.The prismatic slip is harder under CD loading,which makes CD loading present higher yield strength than RD loading.Additionally,the yield anisotropy can be quantified through the inverse ratio of the averaged Schmid Factor of the activated prismatic slip under different loading directions.As for the plasticity anisotropy,the harder and slower slip development under CD loading causes that the CD loading presents larger external force and normal stress on slip plane,thus leading to more significant cleavage fracture than RD loading.Moreover,the micro-crack path under RD loading is more tortuous than CD loading because the fibrous microstructure is elongated along RD,which may suppress the macro fracture under RD loading.These results suggest that weakening the texture and fibrous morphology of microstructure is critical to reduce the differences in slip,damage and fracture behavior along different directions,alleviate the property anisotropy and optimize the service performance of Ti alloy tube formed by hot flow forming.