Superior machinability of steel enhanced with BN and MnS particles

The strategy that replacing part of MnS with BN was proposed in order to decrease the sulfur content in sulfur based free-cutting steel. The effects of BN and MnS inclusions on the microstructure and machinability of the steel were systematically investigated. The results show that most of the BN and MnS inclusions exist individually in the steel and only a small amount of them are in a composite state form- ing either isolated particles or clusters of particles. In the case of multi-phased steel, the theoretical calculation predicts that the volume of large BN particles should be 0.7 times of the volume of large MnS particles. The machinability of this type of BN and MnS alloy steel over a wide range of cutting speeds ranging from a low speed appropriate for drilling to a high speed appropriate for turning is confirmed as being equal to or superior to that of an MnS reference steel, even though the sulfur content in the composite steel is only half that of the MnS steel. The aptitude for cutting effect of 240 ppm nitrogen and 115 ppm boron in the composite steel is demonstrated to be equivalent or even better than 1000 ppm sulfur in MnS free-cutting steel.

Research progress of acupuncture in the treatment of Parkinson's disease

Parkinson's disease(PD)is a common degenerative disease of the central nervous system.The basic and clinical research of acupuncture therapy has witnessed several advances in the treatment of PD.The purpose of this study is to provide some ideas for clinical acupuncture therapy in the treatment of PD.The authors attempt to achieve this objective by systematically organizing the clinical efficacy studies of several acupuncture therapies for PD and elaborating the mechanisms of action in terms of secretion of substantia nigra dopaminergic neurons,level of oxidative stress,inflammatory response,excitotoxicity,and mitochondrial dysfunction.

A cluster-plus-glue-atom composition design approach designated for multi-principal element alloys

Multi-principal element alloys(MPEAs)have shown extraordinary properties in different fields.However,the composition design of MPEAs is still challenging due to the complicated interactions among principal elements(PEs),and even more challenging with precipitates formation.Precipitation can be either beneficial or detrimental in alloys,thus it is important to control precipitates formation on purpose during alloy design.In this work,cluster-plus-glue-atom model(CGM)composition design method which is usually used to describe short-range order in traditional alloys has been successfully extended to MPEAs for precipitation design.The key challenge of extending CGM to MPEAs is the determination of center atom since there are no solvent or solute in MPEAs.Research has found that the element type of center atom was related not only with chemical affinity,but also with atomic volume difference in MPEAs,which has inevitable effect on atomic arrangement.Based on experimental data of MPEAs with precipitates,it was found that elements with either stronger chemical affinity or larger volume difference with other PEs would occupy the center site of clusters.Therefore,a cluster index(P_(C)),which considers both chemical affinity and atomic volume factors,was proposed to assist the determination of center atom in MPEAs.Based on the approach,a solid-solution Zr-Ti-V-Nb-Al BCC alloy was obtained by inhibiting the precipitation,while precipitation-strengthened Al-Cr-FeNi-V FCC alloy and Al-Co-Cr-Fe-Ni BCC alloy were designed by promoting the precipitation.Corresponding experimental results demonstrated that the approach could provide a relatively simple and accurate predication of precipitation and the compositions of precipitations were in line with PEs in cluster in MPEAs.The research may open an effective way for composition design of MPEAs with desired phase structure.