具有规则微结构表面聚丙烯塑件的超声模压粉末成型

利用自制的组合式模具,通过超声模压粉末成型工艺,制得形状尺寸可控的聚丙烯微塑件,成功复制了模芯表面的微沟槽阵列结构。设计单因素实验,研究了超声能量、焊接压力、保压时间对聚丙烯微结构塑件成型的影响。结果表明,适当增加超声能量与焊接压力,可有效提高熔体的填充能力。当超声能量为1000 J、焊接压力为115 kPa、保压时间为8 s时,所制得的微结构塑件具有较好的表面形貌复制率。差示扫描量热和X射线衍射分析表明,超声能量的增加不会改变聚丙烯的晶体结构;随着超声能量的增加,微结构塑件的结晶度降低、晶粒细化。

Effects of three coniferous plantation species on plant-soil feedbacks and soil physical and chemical properties in semiarid mountain ecosystems

Background:Large-scale afforestation can significantly change the ground cover and soil physicochemical properties,especially the soil fertility maintenance and water conservation functions of artificial forests,which are very important in semi-arid mountain ecosystems.However,how different tree species affect soil nutrients and soil physicochemical properties after afforestation,and which is the best plantation species for improving soil fertility and water conservation functions remain largely unknown.Methods:This study investigated the soil nutrient contents of three different plantations(Larix principis-rupprechtii,Picea crassifolia,Pinus tabuliformis),soils and plant-soil feedbacks,as well as the interactions between soil physicochemical properties.Results:The results revealed that the leaves and litter layers strongly influenced soil nutrient availability through biogeochemical processes:P.tabuliformis had higher organic carbon,ratio of organic carbon to total nitrogen(C:N)and organic carbon to total phosphorus(C:P)in the leaves and litter layers than L.principis-rupprechtii or P.crassifolia,suggesting that higher C:N and C:P hindered litter decomposition.As a result,the L.principis-rupprechtii and P.crassifolia plantation forests significantly improved soil nutrients and clay components,compared with the P.tabuliformis plantation forest.Furthermore,the L.principis-rupprechtii and P.crassifolia plantation forests significantly improved the soil capacity,soil total porosity,and capillary porosity,decreased soil bulk density,and enhanced water storage capacity,compared with the P.tabuliformis plantation forest.The results of this study showed that,the strong link between plants and soil was tightly coupled to C:N and C:P,and there was a close correlation between soil particle size distribution and soil physicochemical properties.Conclusions:Therefore,our results recommend planting the L.principis-rupprechtii and P.crassifolia as the preferred tree species to enhance the soil fertility and water conservation functions,especially in semi-arid regions mountain forest ecosystems.

High-entropy alloy and amorphous alloy composites fabricated by ultrasonic vibrations

We successfully fabricate high-entropy alloys and amorphous alloy composites by adopting the proposed ultrasonic vibration method.The low-stress,low-temperature method enables us to create composites that combine both amorphous and crystalline properties.Microscopic observations and computed tomography measurements indicate good bonding quality without pores or cracks in the composites.Due to the unique structure which mixes soft and rigid phases,the composite exhibits improved mechanical performance compared to that obtained from a pure single phase.Our results are promising for the manual design and fabrication of smart materials containing multiple phases and compositions.

CircPlant:An Integrated Tool for circRNA Detection and Functional Prediction in Plants

The recent discovery of circular RNAs(circRNAs)and characterization of their functional roles have opened a new avenue for understanding the biology of genomes.circ RNAs have been implicated to play important roles in a variety of biological processes,but their precise functions remain largely elusive.Currently,a few approaches are available for novel circRNA prediction,but almost all these methods are intended for animal genomes.Considering that the major differences between the organization of plant and mammal genomes cannot be neglected,a plant-specific method is needed to enhance the validity of plant circ RNA identification.In this study,we present Circ Plant,an integrated tool for the exploration of plant circRNAs,potentially acting as competing endogenous RNAs(ceRNAs),and their potential functions.With the incorporation of several unique plant-specific criteria,Circ Plant can accurately detect plant circRNAs from high-throughput RNA-seq data.Based on comparison tests on simulated and real RNA-seq datasets from Arabidopsis thaliana and Oryza sativa,we show that Circ Plant outperforms all evaluated competing tools in both accuracy and efficiency.Circ Plant is freely available at http://bis.zju.edu.cn/circplant.