Underlying slip/twinning activities of Mg-xGd alloys investigated by modified lattice rotation analysis

The inconsistencies regarding the fundamental correlation between Gd content and slip(twinning)activities of Mg alloys appeal further investigations.However,the traditional slip dislocations analysis by TEM is time-consuming,and that by SEM/EBSD cannot recognize the partial slip modes.These urge a more efficient and comprehensive approach to easily distinguish all potential slip modes occurred concurrently in alloy matrix.Here we report a modified lattice rotation analysis that can distinguish all slip systems and provide statistical results for slip activities in Mg alloy matrix.Using this method,the high ductility of Mg-Gd alloy ascribed to the enhanced non-basal slips,cross-slip,and postponed twinning activities by Gd addition is quantitatively clarified.

Theoretical Model and Experimental Research on Friction and Torque Characteristics of Hydro-viscous Drive in Mixed Friction Stage

The hydro-viscous drive(HVD)has been widely used in fan transmission in vehicles,fans,and scraper conveyors for step-less speed regulation or soft starting.In the mixed friction stage,the contact,friction,and torque characteristics of friction pairs are very complex and change at any time.The characteristics of the frictional and hydrodynamic lubrication states were studied in order to calculate and predict the friction and torque characteristics of the friction pairs in the mixed friction stage.The fluid torque was calculated by applying the average shear stress model and the load-carrying capacity of asperity was determined on the basis of the fractal contact theory.In addition,the contact friction coefficient of the friction pairs was taken into consideration and measured by using the MM1000-Ⅲfriction and wear testing machine.The asperity friction torque and total torque in the mixed friction stage were obtained and finally,the test rig for the torque characteristics was set up.The results show that the contribution to the total torque is shared by the oil film and the asperity friction.The friction coefficient decreases sharply at first and then increases with a change in the relative rotational speed,following the Stribeck curve closely,and the contact frictional coefficient slowly decreases with increase in the pressure between the friction pairs.The torque between the friction pairs is provided by the asperity friction,and the torque due to the oil film reduces to zero.When the thickness of the oil film is small,a major contribution to the total torque is due to the asperity friction.The total torque also increases with the decrease in the film thickness ratio.Therefore,by theoretical analysis and experimental verification,the torque of the friction pairs in the mixed friction stage can be accurately calculated using the average shear stress model and asperity friction torque model.

The Influence of Abnormal Segregation Band on Mechanical Properties of Hot Rolled Ferrite/Pearlite Steel Plate

In order to further reveal the influence of abnormal segregation band on mechanical properties of hot rolled ferrite/pearlite steel plate, especially on laminated tensile fracture, the experimental method of delamination tension was adopted. In this paper, the thin tensile samples with 3 mm thickness from the surface, 1/4 positions and center along the thickness orientation of test plate were measured, also the relationship between microstructure and mechanical properties was probed. The results show that the center region of hot rolled ferrite/pearlite steel plate exists granular bainite and ferrite mixed grains, which leads to lower plasticity and toughness of this region. During the tensile process, microcracks are generated and extended at the center of steel plate due to the inconsistency of deformation and fracture on the adjacent structures, finally leading to laminated fracture of steel plate.

Phosphatidylinositol 4-kinase β mutations cause nonsyndromic sensorineural deafness and inner ear malformation

Congenital hearing loss is a common disorder worldwide.Heterogeneous gene variation accounts for approximately 20-25%of such patients.We investigated a five-generation Chinese family with autosomaldominant nonsyndromic sensorineural hearing loss(SNHL).No wave was detected in the pure-tone audiometry,and the auditory brainstem response was absent in all patients.Computed tomography of the patients,as well as of two sporadic SNHL cases,showed bilateral inner ear anomaly,cochlear maldevelopment,absence of the osseous spiral lamina,and an enlarged vestibular aqueduct.Such findings were absent in nonaffected persons.We used linkage analysis and exome sequencing and uncovered a heterozygous missense mutation in the PI4 KB gene(p.Gln121 Arg)encoding phosphatidylinositol 4-kinaseβ(PI4 KB)from the patients in this family.In addition,3 missense PI4 KB(p.Val434 Gly,p.Glu667 Lys,and p.Met739 Arg)mutations were identified in five patients with nonsyndromic SNHL from 57 sporadic cases.No such mutations were present within 600 Chinese controls,the 1000 genome project,gnom AD,or similar databases.Depleting pi4 kb m RNA expression in zebrafish caused inner ear abnormalities and audiosensory impairment,mimicking the patient phenotypes.Moreover,overexpression of 4 human missense PI4 KB mutant m RNAs in zebrafish embryos resulted in impaired hearing function,suggesting dominant-negative effects.Taken together,our results reveal that PI4 KB mutations can cause SNHL and inner ear malformation.PI4 KB should be included in neonatal deafness screening.