羟基磷灰石与氧化锆体积比对钛基复合支架力学性能和腐蚀性能的影响

通过环保、低成本的混合法制备氧化锆(ZrO2)和羟基磷灰石(HA)增强钛基支架材料,该材料具有较低的弹性模量(E)、足够的物理、电化学和生物学性能.研究羟基磷灰石和氧化锆体积分数的变化对支架力学性能、腐蚀性能和抗菌性能的影响.采用扫描电子显微镜结合电子色散光谱和X射线衍射对支架进行表征,通过压缩试验检测材料的力学性能及...     

Calcium phosphate scaffolds for bone repair

Calcium phosphates, with their chemical similarity to bone mineral, show biocompatibility with hard and soft tissues and offer massive potential for bone repair, both as scaffolds to be implanted directly into the defect and as structures for cell transplantation or to guide new bone growth in tissue engineering. This paper reviews the requirements and motivation for synthetic bone graft alternatives and the production routes for, particularly, hydroxyapatite porous scaffolds. It also considers the important role of substitution of ions such as silicate into calcium phosphates so as to more closely mirror the chemistry of bone mineral and to elicit specific biological responses.     

Engineering the biological performance of hierarchical nanostructured poly(ε-carpolactone) scaffolds for bone tissue engineering

Scaffolds play an important role as physical substrates for cell proliferation and differentiation, leading to tissue regeneration. For bone applications, researchers are focusing on cellular or acellular biocompatible biodegradable polymeric scaffolds. However, high biological performance scaffolds are still required to meet actual clinical demands. This paper discusses a novel strategy to engineer the biological performance of polymeric scaffolds through the combined use of additive manufacturing, acetone vapour annealing surface treatment and dopamine grafting, enabling the fabrication of hierarchical nanostructured tissue engineering structures. Produced scaffolds present improved biological behaviour compared to conventional additive manufactured scaffolds, and similar mechanical properties, showing high potential for clinical applications.     

Fabrication and characteristics of novel microelectronic structures fabricated by plasma-based techniques

A number of novel microelectronic structures have recently been produced using plasma-based techniques such as plasma immersion ion implantation (PIII) and this paper describes the recent progress made in this area in our laboratory. Conventional silicon-on-insulator (SOI) substrates utilizing a buried silicon dioxide layer suffer from self-heating effects as device dimensions shrink to the deep-submicrometer regime. Novel SOI structures using dielectric materials with higher thermal conductance such as aluminum nitride and diamond-like carbon have been produced. In the area of high-k (dielectric constant) thin films, plasma nitridation conducted on materials such as zirconium dioxide improves the recrystallization and interfacial properties. In the conventional Smart-Cut™ or ion-cut technique, high-energy hydrogen implantation is performed to effect layer transfer. Low-energy (several hundred eVs) plasma hydrogenation has recently been conducted in conjunction with damage engineering to produce wafer splitting for layer transfer. This new process allows more flexible control of the depth of hydrogen accumulation and the location of layer cleavage.     

A new method for immunosensor preparation: Atmospheric plasma torch

This paper describes a new method for the modification of piezoelectric quartz crystals for immunosensor preparation. The surfaces of the piezoelectric quartz crystals were modified employing Atmospheric Pressure Plasma System using different monomers such as Ethylene diamine (EDA), 1,4-Diaminobutane (DAB) and n-Butylamine (BA). The atmospheric pressure plasma system was adjusted to use the temperature sensitive and volatile monomers. A tunnel from stainless steel was constructed and combined with the plasma torch to introduce the monomers into the plasma jet and preventing the mixing of atmospheric air with the plasma jet. Plasma parameters were; power: 1 kW, pressure: 1 atm, speed of plasma particles: 219 m/s, and exposure time 10 min for EDA and BA monomers, 15 min for DAB monomer. Crystals were characterized by frequency shift measurements, Atomic Force Microscopy (AFM) imaging, contact angle measurements and Infrared (IR) spectra. Frequency shifts for EDA, DAB and BA modified crystals after plasma modification were 56 ± 10, 143 ± 3 and 904 ± 3 Hz respectively. AFM images showed the presence of a film on the surfaces for all monomers. N-H, C-N, C-H and CO group bands were determined in the IR spectra of the crystals. Decrease in the contact angle values of the modified crystals indicated the increase in hydrophilicity. Those results showed that amine containing films on the crystal surfaces were successfully deposited using atmospheric pressure plasma torch. The chemical groups on quartz surface were further activated with gluteraldehyde (GA) and protein immobilisation properties were checked with test antibody (anti-aflatoxin B1) in liquid phase quartz crystal microbalance system. The dip coating method was chosen for immobilisation procedure. After the immobilisation step, chemical structure of surfaces was analyzed by X-ray Photoelectron Spectroscopy.     

Ion implantation and diamond-like coatings of aluminum alloys

In an attempt to increase the wear resistance of some key automotive components, General Motors Research and Development Center initiated a study to determine the potential of surface modification as a means of improving the tribological properties of automotive parts, and to investigate the feasibility of mass producing such parts. This paper describes the plasma immersion ion implantation system that was designed for the study of various options for surface treatment, and it discusses bench testing procedures used for evaluating the surface-treated samples. In particular, both tribological and microstructural analyses are discussed for nitrogen implants and diamond-like hydrocarbon coatings of some aluminum alloys.     

Biomedical production of implants by additive electro-chemical and physical processes

Biomanufacturing integrates life science and engineering fundamentals to produce biocompatible products enhancing the quality of life. The state-of-the-art of this rapidly evolving manufacturing sector is presented and discussed, in particular the additive electrical, chemical and physical processes currently being applied to produce synthetic and biological parts. This fabrication strategy is strongly material-dependent, so the main classes of biomaterials are detailed. It is explained the potential to process composite materials combining synthetic and biological materials, such as cells, proteins and growth factors, as well the interdependences between materials and processes. The techniques commonly used to increase the bioactivity of clinical implants and improve the interface characteristics between biological tissues and implants are also presented.     

基于AduC812单片机的等离子熔积控制系统的设计

在等离子熔积快速成形的强电磁干扰的恶劣环境下,采用数据采集系统芯片AduC812单片机,设计了实现采样、控制一体化的自动控制系统.通过综合采用软硬件抗干扰和信号过滤措施,使该单片机控制系统在恶劣环境下实现了稳定的数据采集和自动控制.     

Ultra-low carbon (ULC) steel modified by triode plasma nitriding and PVD coating: Effects on micro-abrasive wear behavior

Ultra-low carbon (ULC) steels exhibit low yield strength and excellent formability. Plasma Assisted Physical Vapor Deposition (PAPVD) is a potential coating method for enhancing the strength at the surface of these steels [1]. However, when deposited onto low strength alloys PAPVD coatings may undergo premature failure if the substrate plastically deforms under heavy load. Extra load support is usually required for hard coatings to perform satisfactorily. Combined treatments involving plasma nitriding and PAPVD coating have been used to improve the load-bearing capacity of hard films [2]. This work describes the characterization and micro-abrasive wear behavior of Ti-stabilized ULC steels after surface modification by D.C Triode Plasma Nitriding (DC-TPN) and sequential coating with CrAlN by Electron Beam Plasma Assisted Physical Vapor Deposition (EB-PAPVD). Ti-ULC steel, plasma nitrided Ti-ULC steel and Ti-ULC duplex system were characterized by SEM, EDS, XRD analyses, micro-hardness and instrumented indentation hardness measurements, and stylus profilometry. Micro-abrasive wear tests were performed in fixed-ball configuration up to 1350 revolutions using SiC abrasive slurry and a 25 mm diameter — AISI 52100 steel ball. Micro-abrasion mechanisms are presented and discussed. Nitrided steel and duplex systems were, respectively, 2.6 and 3.5 times harder than the untreated Ti-ULC steel. Wear coefficient of nitrided steel was 36% lower than that of the parent Ti-ULC steel. Regression analyses were used to calculate substrate (k_s) and coating (k_c) wear coefficients for the duplex system, the latter being 6.5 times lower than that of the nitrided steel. Coating thickness (3 μm max.) was determined from inner and outer diameter measurements of the wear scars. Results indicate that it is feasible to manufacture duplex Ti-ULC steel via PAPVD, as significant improvements in wear resistance were recorded for both nitrided and duplex-treated steels. Duplex treatment clearly was the most effective method to enhance the wear resistance of ULC steels.     

医用材料聚醚醚酮等离子喷涂表面改性研究进展

聚醚醚酮材料(PEEK)具有良好的生物相容性、化学稳定性、X射线可穿透性及优异的力学性能,广泛用于创伤、脊柱和关节等生物医疗领域。然而,PEEK属于生物惰性材料,其骨整合性不足,这在一定程度上限制了该材料在骨修复与替换等领域的发展和应用。等离子喷涂技术由于工艺简单、经济,喷涂涂层的黏结强度高等特点,是解决聚醚醚酮材料骨整合能力不足的重要表面涂层改性技术。首先,简述了等离子喷涂工艺的涂层沉积机理,并分别对等离子喷涂钛以及羟基磷灰石两种常用涂层进行了介绍;其次,从不同喷涂工艺以及喷涂参数对涂层的影响出发,详细介绍了近几年对PEEK基等离子喷涂涂层的结合强度等机械性能的最新研究进展,并对等离子喷涂过程对PEEK基体的机械强度、疲劳强度、热性能和化学降解等初始性能影响进行了总结与评价,详细介绍了PEEK基等离子喷涂涂层体内外生物性能的最新研究进展;最后,展望了等离子喷涂改性PEEK基材料的临床应用前景,以期为未来设计新型PEEK基生物材料提供理论指导。     

Recent Trends in Newly Developed Plasma-Sprayed and Sintered Coatings for Implant Applications

The current paper aims to review recent trends (2011 to 2015) in newly developed plasma-sprayed and sintered coatings for implant applications. Recent developments in plasma-sprayed and sintered coatings have focused on improving biological performance, bacterial growth resistance, and mechanical properties, predominantly of HA and glass ceramics. The majority of these improvements are attributed to the addition of dopants. To improve biological performance, trace elements, such as Zn and Mg, both of which are found in bone, were added to replicate the functions they provide for the skeletal system. Though bacterial growth resistance is traditionally improved by Ag dopant, the addition of new dopants such as CeO₂ and Zn were explored as well. Great effort has also been made to improve coating adherence and reduce stresses by minimizing coefficient of thermal expansion mismatch between the coating and substrate through the addition of elements such as Zn and Mg or the inclusion of a buffer layer. For sintering process in particular, there was an emphasis on reducing sintering temperature through modification of 45S5 Bioglass. New plasma spray and sintering technologies aimed at reducing high-temperature exposure are briefly introduced as well. These include microplasma spray and spark plasma sintering.     

机床液压系统智能CAD系统的研究与开发

本文论述了作者所开发的机床液压系统智能CAD的结构、功能和开发原理。这一系统不仅可完成设计中的计算和绘图，且能完成传统CAD难以完成的模拟设计师利用知识和经验进行综合分析及方案设计的过程。本文还介绍了建造知识库时知识的表达方式及推理策略。     

生物材料的离子注入表面改性

近年来离子注入技术在改善生物医用材料综合性能方面应用日渐广泛.本文介绍了该技术的特点和作用机理,同时结合国内外学者的研究成果,对其注入工艺、改性效果及改性机理进行了的综述,预期了离子注入在生物材料改性方面的发展趋势和研究方向.     

镁合金作为生物医用材料的腐蚀与防护研究进展

镁合金具有良好的生物相容性及可降解性能,因而有潜力应用于生物医用领域.最近几年,生物医用镁合金的研究得到了广泛的重视.镁合金用于生物医用植入材料的主要问题是耐蚀性差,提高耐蚀性能的方法主要有调整合金成分和采用适当的表面处理技术.本文对镁合金作为生物医用材料的腐蚀机理和影响腐蚀的因素进行了介绍,并总结了最近几年在提高生物医用镁合金耐蚀性能方面取得的进展,最后对生物医用镁合金研究中需要解决的问题和研究趋势进行了分析.     

低温等离子体在材料表面改性中的应用

简要介绍低温等离子体表面改性的原理和装置,综述它在粘接材料、纺织纤维材料和金属材料等改性中的应用。     

环形加热炉液压系统的改造

简述了广州钢铁股份有限公司无缝钢管分厂环形加热炉液压系统改造前存在的问题。介绍了改造后所采用的具有自动卸压装置和按国家现行标准设计制造的密封式液压系统的构成、传动原理和优点。生产实践表明，该密封式液压系统运行状况良好，调整和维护监控方便，设备故障率下降了80％，能满足生产需要。     

Surface enhanced micro features using electrochemical jet processing

This work demonstrates for the first time an augmentation to electrolyte jet processing which allows plasma electrolytic oxidation to be undertaken. Using a sequential process it is possible to produce micro features (≈500 μm width) with a resolution limited only by nozzle geometry but with significant enhancement to substrate surface properties. Here the technique is demonstrated and the resulting modification is compared on the microscale to properties of conventionally produced plasma electrolytic oxide coatings. The technique is further demonstrated through the creation of an exemplar titanium component which features localised surface oxidation treated mating features.     

Transition Element Modifications of Al-Li

The development of aluminum-lithium metallurgy has led to alloys with unsurpassed combinations of density, specific strength, and specific modulus. This paper describes recent advances in the modification of aluminum-lithium binary alloys through additions of the Group IV-A transition metals (titanium, zirconium and hafnium). These elements lead to a duplex precipitation hardening behavior through the formation ofAlJLi and Al₃(TM,Li) (TM = transition element) which act as strengthening precipitates. The influence of the duplex structure on deformation mechanisms and the improvement of mechanical properties in these systems is illustrated by using results for the Al-Li-Zr system.     

等离子喷枪各种送粉方式模拟比较

介绍了等离子喷枪的3种送粉方式，并利用模拟软件分别对3种送粉方式进行模拟试验对比，通过模拟试验分析总结出3种送粉方式的特点：外送粉对材料和能源利用率低；内送粉可以节约材料和能源，达到更好的喷涂效果；中心送粉理论效果很好，但实际应用较难。     

Three-dimensional chitosan-nanohydroxyapatite composite scaffolds for bone tissue engineering

We describe the structure of biodegradable chitosan-nanohydroxyapatite (nHA) composites scaffolds and their interaction with pre-osteoblasts for bone tissue engineering. The scaffolds were fabricated via freezing and lyophilization. The nanocomposite scaffolds were characterized by a highly porous structure and pore size of ∼50–125 μm, irrespective of nHA content. The observed significant enhancement in the biological response of pre-osteoblast on nanocomposite scaffolds expressed in terms of cell attachment, proliferation, and widespread morphology in relation to pure chitosan points toward their potential use as scaffold material for bone regeneration.