Effects of Substrate Pulse Bias Duty Cycle on the Microstructure and Mechanical Properties of Ti–Cu–N Films Deposited by Magnetic Field-Enhanced Arc Ion Plating

Ti–Cu–N films were deposited on 316 L stainless steel substrates by magnetic field-enhanced arc ion plating.The effect of substrate pulse bias duty cycle on the chemical composition,microstructure,surface morphology,mechanical and tribological properties of the films was systemically investigated.The results showed that,with increasing the duty cycle,Cu content decreases from 3.3 to 0.58 at.%.XRD results showed that only Ti N phase is observed for all the deposited films and the preferred orientation transformed from Ti N（200） to Ti N（111） plane with the increase in duty cycle.The surface roughness and deposition rate showed monotonous decrease with increasing the duty cycle.The residual stress and hardness firstly increase and then decrease afterwards with the increase in duty cycle,while the variation of critical load shows reverse trend.Except for the film with duty cycle of 10%,others perform the better wear resistance.

Experimental investigation on upstream-injection interaction with a scramjet cavity flameholder

The study has evaluated the coherent structures and the velocity field of gaseous transverse jet upstream of a scramjet flameholder in a supersonic turbulent flow.The high spatiotemporal resolution coherent structures of the jet plume/wakes and the cavity shear layer were obtained by utilizing the nanoparticle-based planar laser scattering technique.Compared to the no upstream injection case,the cavity shear layer downstream of the jet shows significant mass exchange with mainstream.The particle image velocimetry velocity field and the velocity profiles demonstrated that the interaction intensity of the cavity shear layer with the upstream injection is further enhanced as the injection stagnation pressure increases.

Effect of ciRS-7 expression on clear cell renal cell carcinoma progression

Background:Circular RNA ciRS-7 has been reported to be involved in the progression of various cancers.However,ciRS-7 expression and its role in clear cell renal cell carcinoma(ccRCC)progression remains unclear.This study aimed to investigate the effect of ciRS-7 expression on ccRCC and the related signaling pathway.Methods:ciRS-7 expression was analyzed using quantitative reverse transcription polymerase chain reaction in 87 pairs of ccRCC and matched adjacent normal tissues.The role of ciRS-7 in ccRCC cell proliferation and invasion was determined using the cell counting kit-8 and invasion assays,respectively.Potential mechanisms underlying the role of ciRS-7 in promoting ccRCC progression were explored by Western blotting.The relationship between the expression of ciRS-7 and features of ccRCC was analyzed by the Chi-square test and progression-free survival was determined using a Kaplan-Meier plot.Results:ciRS-7 was overexpressed in ccRCC tissues compared with that in matched adjacent normal tissues.In addition,ciRS-7 up-regulation was closely associated with tumor diameter(P=0.050),clinical stage(P=0.009),and distant metastasis(P=0.007).ciRS-7 knockdown in 786O and 769P cells markedly inhibited their proliferative and invasive abilities.In addition,ciRS-7 inhibition reduced phosphorylated epidermal growth factor receptor(p-EGFR)and phosphorylated serine/threonine kinase(p-Akt)levels.Conclusions:ciRS-7 up-regulation could promote ccRCC cell proliferation and invasion,which may be related with the EGFR/Akt signaling pathway.ciRS-7 might be a potential ccRCC therapeutic target.

Effect of Axial Magnetic Field on the Microstructure, Hardness and Wear Resistance of TiN Films Deposited by Arc Ion Plating

TiN films were deposited on stainless steel substrates by arc ion plating. The influence of an axial magnetic field was examined with regard to the microstructure, chemical elemental composition, mechanical properties and wear resistance of the films. The results showed that the magnetic field puts much effect on the preferred orientation, chemical composition, hardness and wear resistance of TiN films. The preferred orientation of the TiN films changed from（111） to（220） and finally to the coexistence of（111） and（220） texture with the increase in the applied magnetic field intensity. The concentration of N atoms in the TiN films increases with the magnetic field intensity, and the concentration of Ti atoms shows an opposite trend. At first, the hardness and elastic modulus of the TiN films increase and reach a maximum value at 5 m T and then decrease with the further increase in the magnetic field intensity. The high hardness was related to the N/Ti atomic ratio and to a well-pronounced preferred orientation of the（111） planes in the crystallites of the film parallel to the substrate surface. The wear resistance of the Ti N films was significantly improved with the application of the magnetic field, and the lowest wear rate was obtained at magnetic field intensity of 5 m T. Moreover, the wear resistance of the films was related to the hardness H and the H3/E＊2 ratio in the manner that a higher H3/E＊2 ratio was conducive to the enhancement of the wear resistance.

喷孔上游涡流发生器诱导下的横向射流流动特性研究

目的:通过在喷孔上游安装涡流发生器(VG)来研究超声速横向射流(JISC)的流动特性。采用纳米粒子平面激光散射(NPLS)和空间粒子图像测速(SPIV)技术对流场进行观测,并设计三种工况进行对比实验,以研究横向射流的流动特性。创新点:1.采用NPLS和SPIV为实验观测手段,定量化地研究涡流发生器对超声速来流的穿透深度和横向扩散的影响;2.根据实验观测结果展示涡流发生器与横向射流相互作用的流场特性,揭示涡流发生器的混合增强机理。方法:1.采用NPLS流场进行观测,获得瞬态流场灰度图(图6、7和10~12),并分析不同观测平面的瞬态流场结构;2.基于瞬态流场灰度图,通过边缘检测和统计分析方法,提取射流穿透深度和横向扩散边界(图14),并对涡流发生器的混合增强效果进行分析;3.采用SPIV技术对流场进行观测,获得多个观测截面的平均速度场,并根据速度场计算涡量场(图8、11和15),揭示射流流向涡的涡量分布。结论:1.在设计的三个实验工况中,CASE0是横向射流基本工况;与CASE0相比,CASE1中的VG在喷孔附近的羽流两侧产生了两个诱导涡,在形态上形成了一个耳朵形涡结构;CASE2中VG尾流的间歇性大尺度涡对射流迎风侧的诱导涡起主导作用,产生了一个大尺度流向涡。2.与CASE0相比,CASE1中射流的穿透深度和横向扩散边界分别增加了8.5%和17.0%,而CASE2中的穿透深度和横向扩散边界分别增加了26.2%和0.5%;因此,在CASE2中,穿透深度的增加更显著,而横向扩散没有明显改善,这与相互作用模式的涡结构特性有关。3.涡量分布表明,CASE1中存在一个复杂流向涡系统,且VG的尾流在射流反转旋涡对(CVP)的内侧形成了一对诱导涡,而在CASE0中,诱导涡应该在CVP的下方。4.根据多个yoz截面的涡量场分布可以发现,VG促进了射流肾形涡的形成和发展。

Effect of Axial Magnetic Field on the Microstructure and Mechanical Properties of CrN Films Deposited by Arc Ion Plating

CrN films were deposited on the high-speed-steel substrates by arc ion plating. The effect of an axial magnetic field on the microstructure and mechanical properties was investigated. The chemical composition, microstructure, surface morphology, surface roughness, hardness and film/substrate adhesion of the film were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscope（SEM）, surface morphology analyzer, Vickers microhardness test and scratch test. The results showed that the magnetic field puts much effect on the microstructure,chemical composition, hardness and film/substrate adhesion of the Cr N films. The N content increases and Cr content decreases when the magnetic flux density increases from 0 to 30 m T. All of the Cr N films were found to be substoichiometric. With an increase in the magnetic flux density, the film structures change in such way： Cr_2N →Cr_（2-N）＋CrN→CrN＋Cr_2N→CrN.The SEM results showed that the number of macroparticles（MPs） on the film surface is significantly reduced when the magnetic flux density increases to 10 mT or higher. The surface roughness decreases with the magnetic field, which is attributed to the fewer MPs and sputtered craters on the film surface. The hardness value increases from 2074 HV_（0.025） at 0 mT（without magnetic field） and reaches a maximum value of 2509 HV_（0.025） at 10 m T.The further increase in the magnetic flux density leads to a decrease in the film hardness. The critical load of film/substrate adhesion shows a monotonous increase with the increase in magnetic flux density.

Effect of Surface Layer Structural-Phase Modification on Tribological and Strength Properties of a TiC–(Ni–Cr) Metal Ceramic Alloy

This paper reports TiC–（Ni–Cr） metal ceramic alloy（ratio of components 50：50） with nanoscaled components formed in the surface layer and smoothly transformed into the initial inner structure throughout the material under pulsed electron irradiation of the alloy surface. Principal changes in the surface layer are ascribed to the formation of gradient structure leading to the increase in wear resistance of the surface layer, drop of friction coefficient and improvement of specimen bending resistance when stressing on the irradiated surface side. The above changes of tribological and strength properties in the surface layer under pulsed electron irradiation become more apparent with increasing atomic mass of a plasma-forming inert gas.

Fitness-related selection on floral traits in the distylous plant Primula poissonii (Primulaceae)

Aims Reproductive fitness of different floral phenotypes varies within and/or among populations.These variations are important to understand the process of natural selection and the evolution of floral traits.In this study,we focused on a distylous,self-incompat-ible species,Primula poissonii,to investigate fitness-related selec-tion on floral traits.Our aim was to determine how traits vary as targets of natural selection and whether morph-specific selection occurs.Methods This study was conducted at two sites(Yushuizhai at 2700 m and Haligu at 3200 m)in the Lijiang Alpine Botanical Garden,northwest-ern Yunnan,southwestern China.Insects visiting flowers of P.pois-sonii were observed,captured and identified.Randomly selected plants of long-and short-styled morphs were labeled.Five floral/inflorescence traits were measured including floral display,corolla width(CW),floral tube length(FTL),tube opening width(TOW)and floral scape height.Fruit and seed set were recorded.The total num-ber of seeds per individual plant(plant fitness)and seed production per capsule(flower fitness)were calculated.Multiple regression analyses were used to quantify selection gradients.Important Findings The frequencies of the two morphs did not deviate from the expected 1:1 ratio at both sites.Except for FTL,the four other traits did not dif-fer significantly between the long-and short-styled morphs.Floral scape height,floral display and FTL differed between two sites.The selection regimes differed between two morphs and between two sites.At the Yushuizhai site,linear selection for shorter floral tubes was stronger in the short-styled morph.However,nonlinear selec-tion on the floral display was stronger in the long-styled morph than selection on the short-styled morph.At the Haligu site,linear selec-tion for a smaller corolla was stronger in the long-styled morph.A morph-specific nonlinear selection on CW and floral display was also detected.Morph-specific selections were detected through the estimation of flower fitness only in Haligu population.In this site,morph-specific linear selection was also detected for CW and floral display.Morph-specific nonlinear selection on traits was detected only in CW.We found that butterflies and sphingid moths dominated at Yushuizhai,while long-tongued bees dominated at Haligu.The difference in pollinator fauna suggested that selection on floral tubes may be due to differences in pollinator assemblages.Overall,variation of floral and/or inflorescence traits in P.poissonii was probably driven by pollinator selection.Selection regime dif-ferences between two morphs,in part,due the inter-morph diver-gences of sexual functions in distylous plant.