Transfer film effects induced by 3D-printed polyether-ether-ketone with excellent tribological properties for joint prosthesis

Based on the building principle of additive manufacturing,printing orientation mainly determines the tribological properties of joint prostheses.In this study,we created a polyether-ether-ketone(PEEK)joint prosthesis using fused filament fabrication and investigated the effects of printing orientation on its tribological properties using a pin-on-plate tribometer in 25% newborn calf serum.An ultrahigh molecular weight polyethylene transfer film is formed on the surface of PEEK due to the mechanical capture of wear debris by the 3D-printed groove morphology,which is significantly impacted by the printing orientation of PEEK.When the printing orientation was parallel to the sliding direction of friction,the number and size of the transfer film increased due to higher steady stress.This transfer film protected the matrix and reduced the friction coefficient and wear rate of friction pairs by 39.13%and 74.33%,respectively.Furthermore,our findings provide a novel perspective regarding the role of printing orientation in designing knee prostheses,facilitating its practical applications.

Imaging the crystal orientation of 2D transition metal dichalcogenides using polarization-resolved second-harmonic generation

We use laser-scanning nonlinear imaging microscopy in atomically thin transition metal dichalcogenides(TMDs)to reveal information on the crystalline orientation distribution,within the 2D lattice.In particular,we perform polarization-resolved second-harmonic generation(PSHG)imaging in a stationary,raster-scanned chemical vapor deposition(CVD)-grown WS2 flake,in order to obtain with high precision a spatially resolved map of the orientation of its main crystallographic axis(armchair orientation).By fitting the experimental PSHG images of sub-micron resolution into a generalized nonlinear model,we are able to determine the armchair orientation for every pixel of the image of the 2D material,with further improved resolution.This pixel-wise mapping of the armchair orientation of 2D WS2 allows us to distinguish between different domains,reveal fine structure,and estimate the crystal orientation variability,which can be used as a unique crystal quality marker over large areas.The necessity and superiority of a polarization-resolved analysis over intensity-only measurements is experimentally demonstrated,while the advantages of PSHG over other techniques are analysed and discussed.

A 3D biophysical model for cancer spheroid cell-enhanced invasion in collagen-oriented fiber microenvironment

The process of in situ tumors developing into malignant tumors and exhibiting invasive behavior is extremely complicated.From a biophysical point of view,it is a phase change process affected by many factors,including cell-to-cell,cell-to-chemical material,cell-to-environment interaction,etc.In this study,we constructed spheroids based on green fluorescence metastatic breast cancer cells MDA-MB-231 to simulate malignant tumors in vitro,while constructed a three-dimensional(3D)biochip to simulate a micro-environment for the growth and invasion of spheroids.In the experiment,the 3D spheroid was implanted into the chip,and the oriented collagen fibers controlled by collagen concentration and injection rate could guide the MDA-MB-231 cells in the spheroid to undergo directional invasion.The experiment showed that the oriented fibers greatly accelerated the invasion speed of MDA-MB-231 cells compared with the traditional uniform tumor micro-environment,namely obvious invasive branches appeared on the spheroids within 24 hours.In order to analyze this interesting phenomenon,we have developed a quantitative analyzing approach to explore strong angle correlation between the orientation of collagen fibers and invasive direction of cancer cell.The results showed that the oriented collagen fibers produced by the chip can greatly stimulate the invasion potential of cancer cells.This biochip is not only conducive to modeling cancer cell metastasis and studying cell invasion mechanisms,but also has the potential to build a quantitative evaluation platform that can be used in future chemical drug treatments.

An object oriented multi-robotic graphic simulation environment for programming the welding tasks

An object oriented multi robotic graphic simulation environment is described in this paper. Object oriented programming is used to model the physical objects of the robotic workcell in the form of software objects or classes. The virtual objects are defined to provide the user with a user friendly interface including realistic graphic simulation and clarify the software architecture. The programming method of associating the task object with active object effectively increases the software reusability, maintainability and modifiability. Task level programming is also demonstrated through a multi robot welding task that allows the user to concentrate on the most important aspects of the tasks. The multi thread programming technique is used to simulate the interaction of multiple tasks. Finally, a virtual test is carried out in the graphic simulation environment to observe design and program errors and fix them before downloading the software to the real workcell.

Temperature Field Reconstruction in High-Temperature Gas by Using the Colored Background Oriented Schlieren Method

A 3D temperature field reconstruction method using the colored background oriented schlieren(CBOS)method is proposed to address image blurring due to the different refractive index of the multi-wavelength light and significant errors produced when the traditional background oriented schlieren(BOS)method is applied to high-temperature gas.First,the traditional method is employed to reconstruct the non-uniform 3D temperature field.Second,the CBOS method is applied to correct the distortion.Then,by analyzing the correlation coefficient among different color points of the colored background pattern,the non-uniform temperature field is reconstructed much more accurately.Finally,the experimental results are verified by applying the Runge-Kutta ray-tracing method and the thermocouple contact measurement method.The maximum average temperature error of the CBOS-reconstructed temperature field is 12.92°C,compared with the thermocouples.Therefore,an accurate three-dimensional reconstruction of the temperature field can be achieved by the proposed method effectively.

“三三交互、六D联动”导向模式在英语教学中的应用

基于数字化时代与商务业态的新发展时代背景下,市场对于英语专业人才要求越来越高,市场需求的改变直接影响到高校教学目标及教学模式。市场要求人才不仅需要具备英语专业能力,还需要具备综合素养及信息技术技能;而这也是当前高校教学的主要目标。成果导向模式、任务型模式、合作学习模式为英语教学常用教学模式,基于教育改革创新背景下,新型三联教学模式“成果导向+任务型模式+合作学习模式”也随之产生。如何确保三联教学模式的应用效果是当前讨论的重点课题。“三三交互、六D联动”是一种多平台交互、多维度联动模式,对于成果导向任务型合作学习模式英语教学改革及创新有着深刻实践意义。

NAA和2,4-D对东方百合组织培养的影响

借助正交回归多项式建立数学模型的方法,研究了NAA对东方百合＂蒂伯＂（Tiber）鳞片诱导小鳞茎及2,4-D对小叶片诱导愈伤组织的影响,以探讨东方百合组织培养中NAA及2,4-D的用量范围及最佳用量。结果表明,NAA诱导离体鳞片外植体产生小鳞茎的用量范围为0.15～0.9 mg·L^-1,最佳用量为0.69 mg·L^-1;2,4-D诱导叶片形成愈伤组织的最佳用量为3.2 mg·L^-1。

基于Visual C++的SolidWorks三维标准件库

以SolidWorks2 0 0 1和Windows98为平台 ,采用VisualC ++、MicrosoftExcel和MicrosoftAccess等开发工具 ,应用面向对象的程序开发方法 。

东方白鹳mtDNA D-loop序列的多样性

利用线粒体DNA(mtDNA)控制区(D-loop)序列,对东方白鹳的遗传多样性进行了研究。35条长为335bp的mtDNA控制区序列存在11个核苷酸变异位点,定义10种单倍型,序列差异3.28%,核苷酸多态性(Pi)为0.00760,单倍型多态性(Hd)为0.859,核苷酸差异均数(К)为2.545。通过与鹤形目和鹳形目的某些濒危物种线粒体DNA控制区核苷酸多样性进行比较发现,东方白鹳遗传多样性相对较高。

产品创新战略导向与R&D/市场界面关系实证研究

产品创新战略导向对R&D/市场界面管理水平具有重要的影响作用。通过问卷调查的方法,运用统计分析软件,得出如下结论:产品创新市场导向对于R&D/市场界面管理水平具有较大的正向促进作用,技术战略导向对于R&D/市场界面及R&D/市场界面管理水平也有着正向促进作用。最后总结了上述结论的管理学意义,进而针对我国企业实际提出了相应的建议。

基于“资源诅咒”学说的能源输出型城市R&D行为研究——理论解释及其实证检验

文章在Romer的R&D增长模型基础上,将一个纯资本密集型的能源开发部门引入其中,并在最终产品生产函数中加入了能源生产要素,建立了能源输出型城市的四部门内生增长模型,对能源开发与R&D行为之间的关系进行了市场竞争动态均衡分析及平衡增长路径的比较静态分析,为我国能源输出型城市遭受的"资源诅咒"现象提出了一种理论解释,即能源开发对R&D行为的挤出效应。文章还利用36座中国典型的能源输出型城市的面板数据样本对上述理论推断进行了有效验证。最后给出了我国能源输出型城市经济发展的政策建议。

从中国高校的R&D现状看我国研究型大学的建设

文章从分析中国高校的研究与开发入手,对研究型大学进行了界定,最后提出创立和建设我国研究型大学的若干建议。

专利平台驱动的企业创新模式:基于38家高新技术企业的组态分析

实现高水平的科技自立自强,要求企业转变创新模式,从“技术拿来主义”的“外源式”创新走向平台驱动的“内源式”持续创新,专利平台是内源式创新的重要支撑。尽管现有研究关注到专利平台对技术创新的重要作用,但对专利平台的内涵和特征刻画研究不足,导致难以回答“什么样的专利平台在什么条件下能够更好地驱动企业自主创新”。本文创新性地采用“基础区块强度”和“区块赋能强度”来刻画专利平台的内涵,并基于企业结构、战略与环境适配的经典框架,分析企业专利平台结构特征、研发战略导向与外部环境特征的组态对企业自主创新绩效的作用。研究发现:专利平台是驱动企业自主创新的重要基础设施,由其驱动的自主创新组态有4种,具体可归纳为核心专利型平台驱动和专利衍生型平台驱动两类。尽管缺少专利平台驱动的企业也可能获得高自主创新绩效,但本文发现在市场或技术不确定性较大的情境下,这种创新模式难以持续。本文的研究结论对创新管理与平台研究具有一定贡献,对新时期中国企业转变创新模式及如何依托专利平台驱动创新具有重要的启示。

我国R&D强度变化趋势及稳定增长研究——基于创新型国家建设的视角

目前我国R&D强度变化轨迹与国际R&D强度增长模式的第一阶段基本相符,并已进入第二阶段"科技起飞"阶段,正进人一个快速增长的关键时期,但与典型创新型国家相比仍相对较低。不过,经过分析发现,我国R&D强度已较早进入了"科技起飞"阶段,其增长率也与GDP增长率大致持平。因此,我国R&D强度完全有可能实现稳定、快速的增长,早日实现创新型国家的建设。

用面向对象的方法实现3DS文件的读取与操纵

介绍了利用面向对象的程序设计方法实现了3DS文件的读取。与面向过程的方法比较,面向对象方法对于理解3DS文件的读取、重绘及控制显得条理清晰,易于掌握,同时又方便移植到其它应用程序中。基于这一点,提出了将3DS文件的读取工作封装在一个类中,从而提高了程序的可读性。

以结果为中心的韩国R&D评价制度的建立及启示

通过研究科技管理新范式下以结果为中心的韩国R&D评价制度,分析韩国当前科技项目评价体系结构、机制、体制及其制度背后的动因,从中得到引入以结果为中心的评价模式是现阶段研究开发事业良性循环的保障、细致入微的法律制度是科技评价的依据和评价结果客观公正的保障、选择适合的评价机制与体制和合理设置管理机构是促进研究开发事业发展的保障等启示。

D-S证据理论在指纹图像分割中的应用研究

有效的指纹分割能够提高特征提取精度和减少后续处理时间,针对这种情况,提出一种基于D-S证据理论的指纹图像分割算法。该算法首先用改进的灰度方差和均值进行初级分割,然后进行平滑;其次使用方向性和对比度两个信息分别作为两个分类器的特征,并利用模糊规则对各分类器的基本概率分配判断,最后利用D-S证据理论的合成法则将两个分类器的结果进行融合判决,实验结果验证了算法的有效性。

三维空间深度位置上情绪面孔对返回抑制的影响

通过虚拟现实技术构建虚拟三维场景,将Posner线索化范式应用到三维空间,通过两个实验操纵了目标深度、线索有效性以及情绪面孔的效价,考察了三维空间深度位置上情绪面孔如何影响视觉空间返回抑制。结果发现,(1)情绪面孔作为目标时,目标出现在近处空间,情绪面孔效价与返回抑制存在交互作用,负性面孔下的返回抑制减小;(2)情绪面孔作为线索时,目标出现在远处空间,情绪面孔效价与返回抑制存在交互作用,负性面孔下的返回抑制增大。研究表明,三维空间中情绪面孔能够影响返回抑制的大小,且这种影响在远近空间下存在差异。

R&D知识品与我国科技财政的职能定位

研究和开发(R&D)所提供的是具有非竞争性和部分排他性的知识品。由经济学中的公共产品理论所提供的分析框架,R&D知识品可被分为专有技术、共性技术和基础研究带来的科技知识三类。不同的R&D知识品,科技财政对其生产干预的强度、范围和方式上就会有所区别。本文对这些区别进行了梳理,并在最后分析了我国科技财政的职能定位问题。

基于d轴电流直接求解的异步电动机定子磁场定向控制

在异步电动机磁场定向控制系统中,准确的磁场定向是实现高性能控制的前提。在对异步电动机定子磁场定向控制进行了较深入的分析后,提出了一种基于解析计算的定子磁场定向控制的改进方法,给出了计算d轴电流分量的解析计算式。根据该方法,在磁链的控制通道中,没有任何的积分调节器,d轴电流是通过解析式的方法直接计算得到的,克服了常规定子磁场定向控制须加解耦器及其带来的定子磁链输出延时的缺点。实验结果表明:这种方法具有控制性能不受电机转子参数的影响,以及快速的磁链和转矩响应的特点。