With a continuous study on the catalytic mechanism of semiconductors, it has been found that semiconductor materials can undergo catalytic reactions to produce reactive oxygen species under light/ultrasound stimulation. Therefore, it has been widely studied and applied to tumor treatment in recent years. Based on different excitation sources, semiconductor catalytic therapy can be mainly divided into photocatalytic therapy and sonocatalytic therapy. Heterojunctions exhibit better efficacy in tumor catalytic therapy due to their unique electron transfer methods compared to pure semiconductor materials. By analyzing the catalytic mechanism of heterojunction materials, this review classifies variously synthesized inorganic metal heterojunctions in recent years into four categories. Meanwhile, the research and development of different heterojunction materials in the field of photocatalytic and sonocatalytic therapy are discussed in detail. It is hoped to provide a new idea to design inorganic metal heterojunction materials for efficient tumor therapy based on the mechanism of catalytic enhancement of heterojunctions.
Osteoarthritis (osteoarthritis, OA) is a degenerative disease that can lead to disability, often affecting subchondral bone. Damaged articular cartilage and subchondral bone remain challenging to heal independently, and scaffolds for tissue regeneration are a promising therapeutic method. Recently, Magnesium alloys have been considered as promising candidates for biodegradable porous scaffolds due to their good mechanical and biological properties. However, there is still no consensus on the structural design and optimization of magnesium-based scaffolds suitable for subchondral bone regeneration. Therefore, this review summarizes the research progress of magnesium alloys used for osteochondral scaffolds, including fabrication methods of porous scaffolds, optimization strategies involving alloying elements and surface modifications, parametric and non-parametric structural design, degradation, mechanical and biological properties of magnesium-based scaffolds and their influencing factors. Also, this paper discussed the potential directions of future research, intending to provide references for the development and clinical applications of porous magnesium-based scaffolds.
The hot compression test of copper/graphite composites was conducted using a thermal simulation testing machine, Gleeble-3500, to study the thermal deformation behavior of the composites at a deformation temperature of 700-850 °C and a strain rate of 0.001-1.000 s−1. According to the experimental data, the constitutive equation and thermal processing map of the composites were constructed, and the microstructure evolution of the composites was studied by optical microscope. The rheological stress of the composites was studied according to Zener-Hollomon parameter model. The flow stress of the composites decreases with the increase of strain temperature and increases with the increase of strain rate. The calculated thermal deformation activation energy of the composites is 463.02 kJ/mol, which shows that the composites has good formability. The consistency of the maximum stress was verified through the constructed constitutive equation, and it was found that the error between the calculated and experimental values was within 9.5%, indicating that the equation has a guiding role in the rheological behavior of composites materials. The thermal processing map shows that the suitable working temperature is 780-820 °C and the deformation rate is around 0.050-0.100 s−1, when the deformation temperature is 830-850 °C, the deformation rate is about 0.001s−1.
Cobalt ion doped MnO2 was prepared on flexible carbon cloth by constant-current electrodeposition with a loading of 13.8 mg/cm2. The effect of cobalt ion doping on the electrochemical properties of MnO2 was investigated by characterizing the structure and properties of the material using an X-ray diffractometer (XRD), scanning electron microscope (SEM), X-ray photoelectron spectrometer (XPS) and electrochemical workstation. The results showed that when the electrode was assembled with activated carbon to form liquid zinc ion hybrid capacitors (Zn-HCs), the area-specific capacitance of Zn-HCs was as high as 5 883.0 mF/cm2 and the area energy density was 3 154.9 μWh/cm2 at a current density of 2 mA/cm2, comparable to the energy level of zinc ion batteries. When the electrodes were assembled with activated carbon to form quasi-solid flexible Zn-HCs, the Zn-HCs exhibited good energy density (1 351.1 μWh/cm2 at a power density of 1 mW/cm2) and excellent mechanical flexibility, which makes it promising for the next generation of flexible wearable devices.
External fixators, as the most common fixation devices, are widely used in open bone fracture surgeries. However, screws used in conjunction with external fixators are susceptible to infection. Utilizing radio frequency magnetron sputtering technology to prepare Ag-ZnO/Ti nano-composite coatings adhered to the surface of Ti6Al4V screws, it is possible to effectively reduce bacterial adhesion. By adjusting the ratio of target material bonding, the effect of the microstructure of different Ag content in composite coatings on the antibacterial performance of Ti6Al4V screws were investigated. The results indicate that when the volume ratio of Ag, ZnO, Ti target materials are 2:2:96, the mass fraction of Ag in the Ag-ZnO/Ti nanocomposite coating reaches 1.85%, with a roughness of 4.24 nm. The coating surface is smooth and hydrophobic, which is conducive to reducing bacterial adhesion. The cytotoxicity of the coating meets the biosafety standard, with the antibacterial rate as high as 99.62%.
Porous titanium alloys have good mechanical properties, which can reduce the "stress shielding" effect and promote the bonding with biological tissues, but there are still deficiencies in their functionalization. Surface modification can be achieved by modifying the surface morphology of the material or loading functional components on the material surface, thereby imparting good functional properties such as osteoblastic, antimicrobial and corrosion/abrasion resistance. Unlike dense titanium materials such as titanium plates/bars, porous titanium has a complex internal structure, and thus its modification is mostly carried out in fluid (liquid, gas) media to achieve good cladding properties. This paper is categorized according to the principle of surface modification and the nature of the functional components, focusing on surface modification methods and effects of the traditional and new medical porous titanium alloys, and the advantages, disadvantages and influencing factors of different methods are summarized and analyzed, aiming to provide guidance for the surface modification of medical porous titanium alloys.
With the rapid advancement of nanotechnology, nanomaterials have shown unique advantages as novel biomaterials in biomedicine, attracting widespread attention from researchers. Bismuth-based nanomaterials, renowned for their commendable biocompatibility, exceptional optical properties, and other physical and chemical attributes, have been extensively investigated and documented in various biomedical domains, including tumor diagnosis, treatment, and antibacterial applications. This paper provides a brief overview of the research progress of bismuth-based nanomaterials in biomedical imaging techniques such as computed tomography imaging and photoacoustic imaging, as well as their applications in tumor therapy including photodynamic therapy, radiotherapy, and photothermal therapy, as well as antimicrobial therapies. It is hoped that this review will contribute to the application of bismuth-based nanomaterials in biomedicine.
High concentrations of acetone can irritate mucous membranes and cause poisoning, and acetone can also be used as a marker of exhaled gas in the medical field. In order to realize effective detection of acetone gas, WO3 nanomaterials were used to prepare a self-heated gas sensor, and the basic characteristics of the sensor were systematically tested. Based on this, a dual gas sensor array composed of WO3 sensor and SnO2 sensor was designed and the back propagation neural network method was combined to identify acetone mixture gas. In the test of 10−5 volume concentration acetone gas, the results indicated that the response value of the WO3 acetone sensor reached 9.3, the response and recovery time are both 4 s, and the repeatability error is less than 10−8, respectively. The identification error of the dual gas sensor array for acetone and ethanol in the mixed gas is less than 10−8. The results show that prepared WO3 sensor has good response sensitivity, stability, selectivity, transient response and so on, indicating that the multi-sensor fusion technology can realize the effective recognition of mixed gas.
采用激光金属沉积技术制备TC4 钛合金,采用X射线衍射仪、金相显微镜、扫描电子显微镜、显微硬度计等分析TC4 钛合金成型件的物相结构、组织形貌、缺陷裂纹、维氏硬度,以研究打印过程中的激光功率和扫描速率对TC4 钛合金组织及缺陷的影响规律.结果表明:沉积态TC4 钛合金以密排六方结构的α相为主,存在少量的体心立方结构的β相,主要含有细针状、片层状组织.随着激光功率的增加,TC4 钛合金的缺陷逐渐减少.随着扫描速率的升高,柱状晶的宽度和熔覆层间距逐渐减小.激光功率为 550 W、扫描速率为 600 mm/min时,TC4 钛合金的最大维氏硬度达到 409.
研究了Ti-(22,24,26,28)Nb-2Fe-4Sn合金的显微组织和力学性能.使用真空非自耗电弧熔炼炉制备合金铸锭,均匀化处理后对合金铸锭进行冷轧和固溶处理.使用X射线衍射仪和光学显微镜对其物相和微观组织进行分析.通过拉伸试验测定了合金的力学性能,使用扫描电子显微镜观察了拉伸样品断口形貌.结果表明,Ti-(22,24,26,28)Nb-2Fe-4Sn合金具有单一β相.Nb的加入使合金的β相稳定性提高,合金的变形机制由孪晶变形转变为位错滑移变形,孪晶诱导塑性变形使得合金具有较高的伸长率.所有合金拉伸断口呈韧性断裂特征.Ti-26Nb-2Fe-4Sn合金的弹性模量为 59 GPa,伸长率为 19%,抗拉强度为 621 MPa,具有良好的生物医学应用前景.
作为具备良好发展前景的可时效强化镁合金,Mg-Sn合金通过Mg2Sn相析出强化、固溶强化与细晶强化获得了优异的性能.与Mg-Zn、Mg-Al主要镁合金相比,Sn在Mg中的固溶度较好,析出强化效果优异;另外,Mg2Sn相的熔点高达 771.5℃,使Mg-Sn合金成为非稀土系列的低成本耐热镁合金.从合金化、固溶-时效处理工艺分析总结了可时效强化Mg-Sn合金的研究进展,分析Mg-Sn合金时效行为的重要参数及其影响因素,主要目的为细化Mg2Sn析出相或增加Mg2Sn析出相数量;同时,对添加到Mg-Sn合金中的合金元素的固溶效果、细晶效果与形成三元强化相效果进行系统总结与分析,为Mg-Sn合金成分的设计和性能改善提供重要参考.
316L不锈钢具备良好的力学性能、焊接性能、耐蚀性能,被广泛应用于化工管道、船舶及核电等领域.因其应用环境复杂,316L不锈钢在特定介质环境和拉应力的协同作用下,易发生应力腐蚀开裂,导致严重事故.概述了 316L不锈钢应力腐蚀裂纹萌生及扩展的规律,总结了其应力腐蚀的阳极溶解和氢致开裂两种微观主导机制的特点.在此基础上,针对介质环境、材料、表面应力状态 3 个影响因素,综述了近年来通过调节介质环境的pH、溶液浓度、引入压应力、优化微观结构及涂层工艺等方面,改善 316L不锈钢应力腐蚀性能的研究进展.最后,基于 316L不锈钢面临的应力腐蚀问题,从应力腐蚀机制和防护措施两方面展望了 316L不锈钢应力腐蚀的研究热点和方向.
日前,记者从沈阳工业大学了解到,该校武祥教授团队研制出一种新型正极材料,将锌离子电池的循环寿命提高到 6500 次,有效改善了锌离子电池寿命短的问题.这将进一步推动锌离子电池研究走向成熟,并为开发可持续能源提供新的方案.
采用磁控溅射技术在单晶Si基片上交替沉积CrN层、ZrYN层,制备不同厚度ZrYN层的CrN/ZrYN纳米多层膜.利用X射线衍射仪、扫描电子显微镜、透射电子显微镜、纳米压痕仪表征纳米多层膜的微观结构和力学性能.结果表明:随着ZrYN层厚度的增大,纳米多层膜中CrN相的结晶程度呈现出先上升后下降的趋势;纳米多层膜的硬度、弹性模量、韧性也呈现出先增大后减小的趋势;当ZrYN层厚度为 0.9 nm时,纳米多层膜具有最高的硬度、弹性模量、韧性,分别为 20.3 GPa、210.4 GPa、2.25 MPa·m1/2.上述结果表明,随着ZrYN层厚度的增大,纳米多层膜出现由晶态向非晶态转变,在非晶态下,能够获得良好的综合力学性能.
2023 年 9 月 15 日在广东省梅州市举行的科技成果评价会上获悉,我国科学家成功研发出风化壳型稀土矿电驱开采技术,稀土回收率提高约 30％,杂质含量降低约 70％,开采时间缩短约70％.据了解,风化壳型稀土矿是我国的特色资源.目前普遍采用的铵盐原地浸取技术在生态环境、资源利用效率、浸出周期等方面存在的问题制约了我国稀土资源的高效绿色利用.
晶界工程是改善晶界特性以提高抗晶间退化能力的一种可行方法,能有效提高Σ重位点阵晶界的比例.研究基于 304 奥氏体不锈钢,通过控制不同的热机械加工工艺,以获得更高的Σ重位点阵晶界,优化晶界特征分布,利用电子背散射衍射技术分析不同样品的微观结构,通过室温拉伸试验研究晶界类型对 304 型奥氏体不锈钢力学性能的影响.结果表明,经过晶界工程处理的样品,其伸长率能得到一定程度的提升.分析断口微观形貌、平均施密特因子、泰勒因子得出,晶界工程处理能使得 304 奥氏体不锈钢基体内的第二相杂质减少、微观区域应变分布更均匀、滑移系统的激活过程更容易发生.
采用激光熔化沉积(laser melting deposition,LMD)成形Cu-Al-Mn-Ti形状记忆合金,研究其组织、冶金缺陷与性能特点.研究表明,LMD成形Cu-Al-Mn-Ti合金的显微组织具有各向异性特征:建造面为柱状晶组织,扫描面为等轴晶组织.这是由于LMD成形过程沉积方向存在较大的温度梯度导致的.LMD成形Cu-Al-Mn-Ti合金的基体组织为β相板条马氏体,并存在大量Cu2AlMn颗粒状析出相.孔隙缺陷是LMD成形Cu-Al-Mn-Ti合金中主要的冶金缺陷,严重影响了合金的力学性能.热处理可提高LMD成形Cu-Al-Mn-Ti合金的力学性能及形状记忆性能.固溶、时效处理后,LMD成形Cu-Al-Mn-Ti合金的抗拉强度可由 453.6 MPa提高至 519.5 MPa,形状回复率可由 68%提高至 97%;当时效温度为 500℃时,在晶界上开始析出网状α相导致Cu基体中的Al含量增加,使合金的力学性能和形状回复率下降.
在钛和钛合金表面制备羟基磷灰石(hydroxyapatite,HAp)涂层能够显著提升其生物活性.HAp中进一步掺杂Cu,可以获得抗菌效果,有效避免术后感染.为研究温度对纯钛表面制备Cu掺杂羟基磷灰石(CuHAp)涂层形貌的影响,采用电化学沉积的方法,在不同温度下制备CuHAp涂层.采用扫描电子显微镜、能量色散X射线光谱仪、X射线衍射仪对涂层的表面形貌、元素含量和物相组成进行表征.结果表明:随着沉积温度的升高,沉积过程中的电流密度也随之增大.沉积温度由 25℃升高至 45℃,会加快CuHAp涂层致密均匀的生长;但温度升高到 55℃时,CuHAp涂层变得疏松,并且出现裂纹.沉积温度低于 45℃时,Ca+Cu与P的物质的量比小于 1.67,有利于骨生长.适当提高沉积温度,可以得到均匀致密的CuHAp涂层.
随着社会的发展,人们的日常生产生活对电热材料提出了更高的要求.碳纳米管因具有轻质、高电导率、高电热转换效率等特点,成为新型轻质高效电热材料的研究热点.纳米尺度的单根碳纳米管无法直接使用,因此,需要以有序的宏观形态进行组装以获得可用的高性能电热材料.介绍了基于碳纳米管的电热材料的主要宏观组装形态,对其结构设计进行了阐述,并对其应用方向进行了介绍,最后对碳纳米管的进一步工业化应用进行了展望.
针对钛合金弹性模量快速预测的需要,采用合金设计公式对原始合金数据进行转换,利用转换所得的Mo当量、d-电子结合次数和d-电子结合能作为数据集;采用多层感知器、随机森林网络和卷积神经网络三种机器学习方法,基于数据驱动方式搭建钛合金成分与弹性模量的关系模型.结果表明,相比随机森林网络模型和卷积神经网络模型,多层感知器模型具有更优的预测性能和预测精度.此外,多层感知器模型的预测能力符合预期,其相关指数评分达到 0.66,均方根误差为 7.54 GPa;说明多层感知器适用于医用钛合金的数据挖掘和研发.
