This study investigated the precipitation behavior and morphological evolution of alpha phase including intragranular alpha and grain boundary alpha (GB-alpha) in a laser-directed energy deposition (L-DED) processed metastable beta-Ti alloy (Ti-38644), focusing on the effects of heat treatment conditions and carbon addition. During both direct aging and solution and aging treatments, as the heat treatment temperature increased, the size of the intragranular alpha increased. The carbon addition decreased the intragranular alpha sizes. Meanwhile, GB-alpha preferentially nucleated at high-angle grain boundaries due to solute segregation (Al, O) and high interfacial energy. In addition, trace carbon addition (0.07 wt. %) introduced Ti2C precipitates, which disrupted solute transport, and physically impeded alpha lateral growth. As a result, continuous GB-alpha was transformed into discontinuous blocky forms, alpha laths were refined, and precipitate-free zones (PFZs) were eliminated. Furthermore, the side alpha plates (alpha sp) near GB-alpha were replaced by isolated point-like alpha variants or suppressed entirely due to variant interference and carbide-induced stress fields. These findings provided a comprehensive mechanism for GB-alpha regulation through heat treatment design and carbon engineering, enabling microstructure optimization for enhanced mechanical properties in L-DED metastable beta titanium alloys.

Aim or purpose: Titanium (Ti) is widely used in medicine due to its excellent biomechanical properties, but precise nano-fabrication of its surfaces is challenging. We developed a DNA-nanocoating system to functionalize Ti surfaces and explored the effects of tetrahedral DNA (TDNs) on rat bone marrow mesenchymal stem cells (rBMSCs) adhesion, proliferation, and osteogenic differentiation, as well as their biological effects under hypoxic and inflammatory conditions. Materials and methods: Clickable Ti surface made via hydroxylation, silanization, click chemistry. FE-SEM, XPS analyzed roughness, composition. Confocal imaging showed 30 nm and 7 nm-TDNs on Ti. Contact angle tested hydrophilicity. rBMSCs cultured on TDNs-modified Ti for adhesion, proliferation (CCK-8), osteogenic differentiation (ALP, ARS, qRT-PCR). In vivo, TDNs-modified Ti rods implanted in mice femurs, bone formation analyzed by micro-CT, H&E, Van Gieson staining. Results: 1. Developed a DNA nanocoating system for titanium surfaces using hydroxylation, silanization, click chemistry, and base-pairing. 2. Assembled 30 nm and 7 nm TDNs; 30 nm TDNs showed better cellular responses and osteointegration via focal adhesion pathway. 3. 30 nm TDN-modified surfaces performed better under inflammatory and hypoxic conditions. Conclusions: We functionalized Ti surfaces with ssDNA overhangs via click reaction and assembled 30 nm and 7 nm TDNs. The 30 nm TDNs significantly enhanced Ti surface hydrophilicity, cell proliferation, and osteogenic differentiation, and maintained performance under inflammatory and hypoxic conditions.

Adding metal ions is a promising strategy to enhance the biological performance of titanium implants. In this study, we aimed to explore the effects of yttrium on the osseointegration of titanium implants. First, a series of yttrium-doped titanium surfaces were fabricated via microarc oxidation (MAO) by incorporating yttrium acetate into the electrolyte, and then the surface characteristics of different substrates were evaluated. Subsequently, the cellular behaviors of different coatings were assessed, and the osteointegration effects were examined using a rat model. Finally, high-throughput sequencing was employed to elucidate the underlying mechanisms of the yttrium-doped MAO coatings. As the results indicated, the proportion of yttrium in the coatings increased as the concentration of yttrium acetate improved. Surface characterization revealed that the yttrium-doped MAO coatings exhibited a homogeneous porous morphology, with comparable roughness and wettability to those of the undoped MAO coating, while the morphology became inconsistent when the yttrium acetate concentration reached 30 mM. The in vitro assays demonstrated that the addition of yttrium notably improved the cell adhesion, spreading, proliferation, and osteogenic differentiation of MAO coatings when doped with a low proportion, accompanied by enhanced osseointegration according to the in vivo experiments. Further exploration revealed a significant enrichment of osseointegration-related signaling factors and the activation of BMP/Smad signaling in the effects of yttrium-doped titanium coatings, which was attributed to the excessive accumulation of phosphorylated Smad1/5/9 in the nucleus. In summary, our work demonstrates that the use of MAO coatings doped with a low proportion of yttrium can enhance the osseointegration of titanium implants, providing an efficient strategy to optimize titanium implant performance.

Titanium (Ti) is extensively used in the medical field because of its excellent biomechanical properties; however, how to precisely fabricate Ti surfaces at a nanoscale remains challenging. In this study, a DNA nanocoating system to functionalize Ti surfaces via a series of sequential reactions involving hydroxylation, silanization, and click chemistry is developed. Tetrahedral DNA nanostructures (TDNs) of two different sizes (≈7 and 30 nm) are assembled and characterized for subsequent surface attachment. In vitro and in vivo assays demonstrated significantly enhanced cell adhesion, spreading, proliferation, osteogenesis, and osseointegration on Ti surfaces modified with 30‐nm TDNs, compared to slightly improved effects with 7‐nm TDNs. Mechanistic studies showed that the focal adhesion pathway contributed to the enhanced bioaffinity of the 30‐nm TDNs, as evidenced by the upregulated expression of vinculin and activation of the Akt signaling pathway. Moreover, under inflammatory or hypoxic conditions, Ti surfaces modified with 30‐nm TDNs maintained excellent cellular performance comparable to that under normal conditions, suggesting a broader adaptability for DNA nanoparticles. Thus, better performance is achieved following modification with 30‐nm TDNs. In summary, the proposed DNA‐guided nanocoating system provides a novel and efficient strategy for the surface nanofabrication of Ti.

Peri-implantitis and insufficient osseointegration are major challenges currently facing dental implants. Therefore, enhancing the antibacterial and bioactive properties of implants is crucial. This study developed a novel Ce-doped porous coating on low-modulus Ti40Nb alloy by micro-arc oxidation to improve antibacterial and bioactive properties. We systematically investigated the microstructure, phase composition, adhesion to the substrate, hydrophilicity, antibacterial and cell compatibility of the coatings, and the effect of Ce content on the coating formation was discussed. The increase in the concentration of Ce3+ ions in the coating significantly enhances its antibacterial properties. The introduction of the porous structure endows the coating with excellent osteogenic differentiation activity, indicating that the cerium-doped MAO coating on the Ti40Nb alloy has great potential in dental applications.

In this study, we designed the processing windows for laser powder bed fusion (LPBF) of Ti-6Al-4V (Ti-64) alloy by using central composite design and made a detailed investigation into the influence of processing parameters on the defects. The purpose is to investigate the effect of defects on mechanical properties. It was found that insufficient energy density could lead to the formation of lack of fusion (LOF) defects and produce non-melted powders on the surface, while excessive energy density could lead to cracks that were detrimental to mechanical performance. In addition, the microstructural evaluation found that relatively low energy density could lead to shorter columnar prior-β grains, while prior-β grains in the sample processed by the high energy density extended almost the entire height of the cross-section, which could lead to the strong mechanical property anisotropy. The prior β grains are formed by heterogeneous nucleation on the partially melted material powder. As the energy input increases, all the powder powders in the molten pool can be melted so that these particles do not act as nucleation sites and the prior β grain can grow through more layers without forming new grains being able to nucleate. The prior β-grain in as-built Ti-64 samples consisted of acicular α’ martensite with myriads of lattice distortions, as a precursor to a phase transition, which lead to strong tensile strength and poor ductility. Annealing heat treatment promoted the improvement of the ductile performance of LPBF Ti-64. Overall, this study provides comprehensive views on the effects of processing parameters (laser power, scanning speed, and hatch distance) on the internal (pores and LOF) and external (unmelted powder, sintering neck, and crack), defects, microstructure, and tensile property evaluation of LPBF Ti-64, which offer insights for the development of additive manufactured titanium alloys with excellent mechanical property.

Hypothesis: The water wettability of a hydrophilic surface is dictated by the hydration of the region less than 1 nm below the surface plane, yet it hitherto remains a topic rarely touched upon how a subtle change in surface structural features at molecular level affects the surface wettability and its response to the environmental nature. Experiments: Binary self -assembled monolayers (SAMs) consisting of plain and functional thiols were constructed, where the surface fraction of the functional thiols was varied from 0.1 to 0.3, 0.6, 0.8 and 1.0 and the difference in CH 2 unit number between two types of thiols - defined as height difference between surface polar (OH, NH 2 , COOH, or H 2 PO 3 ) and non -polar (CH 3 ) groups - from 0 to 1, 3, and 5. The surface wettability of as -prepared binary SAMs and their surface energy were assessed in both air/water/solid and oil/water/solid triphasic systems. Findings: With the relative height of surface H 2 PO 3 groups being deliberately set as 3 in particular, as -prepared binary SAMs gain unique environmentally adaptable surface lyophobicity, namely, they can be both oleophobic in water and hydrophobic in oil. Thanks to this new environmentally adaptable surface lyophobicity, such binary SAM coating enables copper meshes to realize selective and efficient oil/water separation without need of prewetting. Both the polar and dispersion interaction components of surface energy of the binary SAM coatings are found crucial to effective oil/water separation of the coated copper meshes; the former defines critical intrusion pressure and the latter must be larger than 22 nN/m.

Titanium and titanium alloys are the most commonly used implant materials, but they are biologically inert. These materials lack rapid osseointegration and resistance to bacterial infections, problems that remain unsolved. The preparation of titanium dioxide coatings by microarc oxidation improves both the biocompatibility of titanium-based materials and their resistance to corrosion during long-term presence in the body. This paper discusses and summarizes the mechanisms of microarc oxidation and some classical models that need to be developed to provide a better understanding and guidance for future research. Subsequently, the effects of electrolyte type, additives, and surface modification of the microarc oxidized coating on the coating morphology were analyzed in detail. In addition, biological applications of microarc oxidation coatings are analyzed, including antimicrobial properties, osseointegration, hydrophilicity, corrosion resistance, and wear resistance.

HYPOTHESIS:Integration of ultralow surface energy and surface functionality on one surface coatings is highly desirable in chemical and biomedical applications. However, it is a fundamental challenge to reduce surface energy without cost of surface functionality and vice versa. To address this challenge, the present work made use of the rapid and reversible change of surface orientation conformations of weak polyelectrolyte multilayers to create ionic, perfluorinated surfaces. EXPERIMENTS:Poly(allylamine hydrochloride) (PAH) chains and the micelles of sodium perfluorooctanoate (SPFO) were layer-by-layer (LbL) assembled into (SPFO/PAH)n multilayer films, which readily exfoliated to freestanding membranes. The static and dynamic surface wetting behaviors of the resulting membranes were studied by sessile drop technique and their surface charge behaviors in water by electrokinetic analysis. FINDINGS:As-prepared (SPFO/PAH)n membranes exhibited ultralow surface energy in air; the lowest surface energy is 2.6 ± 0.5 mJ/m2 for PAH-capped surfaces and 7.0 ± 0.9 mJ/m2 for SPFO-capped surfaces. They readily became positively charged in water, which allowed not only effective adsorption of ionic species for further functionalization with subtle change in surface energy, but effective adhesion onto various solid substrates such as glass, stainless steel, and polytetrafluoroethylene to endorse the wide applicability of (SPFO/PAH)n membranes.

原有"电子测量实验"课程存在验证性实验多、综合性设计型实验少、与前沿理论联系不紧密、实验平台缺乏等问题,无法满足课程培养目标.针对上述问题,构建了"基础实验+综合拓展+科研引导"的递进式多层次实验课程体系;引入翻转课堂提升实验教学效果;研制开放式实验教学平台,支撑多层次个性化课程内容.应用表明,该课程体系提升学生应用前沿技术解决实际问题能力,锻炼学生创新思维.

Introduction: Drugs and biocompatible nanoparticles have raised significant potential in advancing the bone regeneration. Electrospinning technology enables the full realization of the value of drugs and nanoparticles. Methods: In this study, we have successfully fabricated core-sheath nanofibers solely composed of polycaprolactone (PCL) polymer. Simvastatin (SIM) was confined to the core of the nanofibers while nanohydroxyapatite (nHA) was loaded on the nanofiber surface. Results: All the prepared nanofibers exhibited a cylindrical micromorphology, and the core-sheath structure was exploited using a Transmission Electron Microscope. X-ray pattern results indicated that SIM was in an amorphous state within nanofibers, while Fourier Transform InfraRed spectroscopy showed excellent chemical compatibility among SIM, nHA, and PCL. The actual loading of nHA within the nanofiber was determined by a thermogravimetric test due to the high melting point of nHA. Core-sheath nanofibers could release SIM for 672 h, which was attributed to the core-sheath structure. Furthermore, nanofibers loaded with SIM or nHA had a positive impact on cell proliferation, with the core-sheath nanofibers displaying the most favorable cell proliferation behavior. Discussion: Such a synergistic facilitation strategy based on materials and nanostructure may encourage researchers to exploit new biomedical materials in future.

阻塞型睡眠呼吸暂停综合征(OSAS)是常见的睡眠类疾病,为满足居家对OSAS进行初步筛查和诊断,该文设计了基于聚偏氟乙烯(PVDF)压电薄膜的鼾声监测系统.可穿戴式的鼾声监测系统包含高灵敏度鼾声传感器、低噪声信号调理电路、嵌入式系统及上位机系统.根据鼾声段和非鼾声段能量差异大的特点,基于短时能量法进行鼾声端点检测算法设计,通过采集的鼾声信号进行算法验证.经测试,系统采集的鼾声信号信噪比高,端点检测平均误差小于0.032 s,准确率达92.6％,满足潜在OSAS患者的筛查要求以及进行康复训练的自我检查,同时可减轻患者筛查和医学多导睡眠图(PSG)检测的负担.

设计了 一组跟随式移动机器人系统,通过图像的识别与处理构建局部通信网络,完成机器人自动跟随、协同控制的功能.建立机器人运动模型,根据采集的图像信息通过PID控制算法控制机器人,通过广播网络的构建,使用广播通信方式完成机器人协同控制.单机器人在直行与转向运动测试中均具有良好的跟随表现,多机器人跟随系统具有较好的跟随鲁棒性,同时可完成多机器人的协同控制.

Based on the tactile mechanism of human fingertips, a bionic tactile sensor fabricated from polyvinylidene fluoride piezoelectric film is proposed, which can identify the surface softness, viscoelasticity, thermal conductivity, and texture roughness of the object. The tactile sensor is mounted on the fingertip of the bionic manipulator, which obtains the surface features by touching and sliding the object. The time-domain features of the output signal are used for preliminarily discriminating the softness, viscoelasticity, and heat conduction of the object. Finally, based on the Back Propagation and the Particle Swarm Optimization-Back Propagation neural network algorithm, the recognition experiment of texture roughness is carried out using the PSO algorithm to improve the BP neural network so that the optimized BP algorithm has a higher convergence accuracy. The results show that the PSO-BP algorithm achieved the highest accuracy of 98% for identifying samples with different roughnesses and the average recognition achieved an accuracy of 94%. The bionic piezoelectric tactile sensor proposed in this paper has a good application development prospect in recognizing the surface features of objects and intelligent robots.

为解决夜晚值班人员犯困的问题,设计具有自主避障、自适应构图、自主导航及定位等功能的可辅助值守人员巡逻的自适应仓库值守机器人.利用光电、陀螺仪、激光雷达等传感器进行感知,由搭载ROS(Robot Operating System)机器人操作系统的Intel5微处理器进行控制.采用开源设计模式,结合SLAM(Simultaneous Localization And Mapping)及模拟键盘控制技术,并搭载摄像头、噪声采集模块等多种环境监测传感器,使用TeamViewer进行远程监控以实时获取当前机器人的位置及状态信息,具有较强的兼容性和扩展性.经测试表明,该自适应值守机器人能摆脱键盘自主建图,实现巡逻等各项辅助值守人员的工作,有很好的市场应用价值.

Ti6Al4V alloy exhibits good biocompatibility and has a wide range of applications in the medical fields. Additive manufacturing, especially selective laser melting (SLM), provides a new and effective way for the fabrication of Ti6Al4V alloy biological components. The corrosion resistance of SLM processed Ti6Al4V alloy needs further investigation, which is important for the application of biological components. In this study, Ti6Al4V alloy was fabricated by SLM using different process parameters. Electrochemical measurements including open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy were performed to study the influence of laser scan speed on the corrosion behavior of SLM fabricated Ti6Al4V specimens. The corrosion resistance on different planes of SLM fabricated Ti6Al4V alloy was further characterized. The electrochemical measurements indicated that the corrosion resistance was reduced as the laser scan speed increased. Microstructure analysis suggested that the inferior corrosion resistance under a high laser scan speed was related to the decreased densification behavior. Compared to the XZ-plane, the XY-plane possesses a superior corrosion resistance. The anisotropic corrosion resistance on XY- and XZ-planes of SLM fabricated Ti6Al4V alloys is attributed to the different microstructures on different planes, where more α′ martensite and less β-Ti phase were formed on the XZ-plane than on the XY-plane.

吉大仪电开放实验室一直在探索实践创新能力培养新模式,寻求适合工科类本科生的实践类教育方法,改变实验室只提供实验设备和场地的一贯模式,发挥理论课教师、实验教师与科研一线教师的各自优势,加入到开放实验室实践教育中,依托学生兴趣、竞争机制、交流平台、能力培训、实践创新等五维一体的模式进行本科生实践创新能力培养.5年的实践逐步完成了高素质创新性人才培养模式的构建,为大学生创业实践活动的开展奠定了坚实的基础.

为改善现阶段渔业养殖、水下环境监测、水质检测等领域人员作业困难、效率低下的问题,设计了一款具有水样采集功能的观测型水下机器人,该设计搭载了传感器和水样采集装置采集水体环境信息.首先进行了水样采集实验,验证其运动能力和水样采集能力.然后针对自然水域采集的图像,采取动态阈值白平衡的方法,去除光源强度和色偏的影响.最后使用对比度拉伸、直方图均衡、限制对比度自适应直方图均衡(CLAHE:Contrast Limited Adaptive Histogram Equalization)3种算法进行图像增强,选取对比度、信息熵和平均梯度进行像质评价.实验结果表明,该设计具有操作灵活,交互性强的特点,CLAHE方法明显提升了水下图像细节,为科研实验、水下探测和环境保护等方面提供了新途径.

Real-time monitoring of seismic information is important, a wide variety of geophones have emerged to achieve this goal. According to the principle of transforming seismic signals, the geophones can be classified into electromagnetic geophones, piezoelectric geophones, electrochemical geophones, fiber optic geophones and so on. Among them, piezoelectric geophones have been widely used in seismic detection. In this article, the piezoelectric material is briefly introduced at first, and then the piezoelectric seismic detector with piezoelectric ceramic and polyvinylidene fluoride as a sensitive material is involved. After analyzing the electrical equivalent model of the piezoelectric sensitive unit, the signal conditioning circuit of the piezoelectric geophone is summarized as well. After that, the promotion of MEMS technology to piezoelectric geophones is discussed. Finally, a summary of all the work listed in this article is given and an outlook of combining MEMS and PVDF to improve the performance of geophones is proposed.