医用钛表面生物活性化研究

钛及钛合金具有优良的生物相容性和机械性能，已应用于临床．尤其是用作骨替换与修复材料。但是．钛属于生物惰性材料．不能与骨组织形成化学键合或称骨键合。通过表面改性可使其在生理环境具有诱导羟基磷灰石在表面自发生长的能力．即生物活性化。这是当今生物医用材料研究的热点领域之一。本文评述了钛表面生物活化的研究现状．简要总结了本课题组在这方面的研究工作。     

生物医用多孔钛的表面仿生处理研究进展

介绍了钛作为生物医用材料的研究现状.针对多孔钛的结构特点,综述了当前生物医用材料的各种表面活化方法,如溶胶-凝胶法、预钙化处理法、碱热处理法、酸碱两步法等,总结了当前多孔钛表面改性和骨诱导机理的研究现状.     

钛基生物复合材料的研究进展

钛及钛合金由于具有优秀的抗腐蚀性、生物相容性、低密度和高的比强度等特性,而被应用于生物医学方面。然而,与人骨相比,钛合金的弹性模量较高,可达100～110GPa,而人骨的弹性模量只有10～30 GPa。虽然与其它金属材料相比具有与骨较为接近的弹性模量,但仍远远高于骨的弹性模量,这就容易造成钛与人体骨界面上力学性能的不匹配,如直接植入则会带来“应力屏蔽“效应,因此对钛及钛合金进行处理来降低弹性模量和提高活性成为当前研究的热点。目前主要通过两种途径来改善纯钛及其合金的生物活性和生物相容性问题,一种就是通过各种不同工艺在纯钛及其合金表面涂覆羟基磷灰石及生物玻璃涂层,另一种是将生物活性材料HA作为一种活性相混入纯钛及其合金中,形成一种微观复合材料。本文重点介绍了近年来钛基生物复合材料的研究进展。     

新型生物活性材料的设计和研究进展

生物活性材料是生物医用材料领域中一个重要的研究方向.研究表明,在体液的作用下这类材料的表面能够形成Si-OH、Ti-OH、Ta-OH、-COOH和PO4H2等功能基团,从而诱导类骨磷灰石层生成并与骨发生键合.综述了人们利用医用金属进行表面生物活化或通过有机/无机复合的方法得到力学性能良好的新型生物活性材料,为人工植入体的临床应用提供了更广阔的前景.     

生物医用多孔钛及钛合金的研究进展

多孔钛和钛合金因具有优异的生物相容性、与人骨力学性能匹配良好、可作为植入物材料的优点,而引起了广泛关注。介绍了医用多孔钛及钛合金的产生背景,综述了近几年国内外对生物医用多孔钛及钛合金的制备方法、微结构特征与性能的关系、表面处理的研究进展,并展望了生物医用多孔材料的发展。     

医用金属表面含锶涂层耐蚀性和生物相容性研究进展

随着全球人口老龄化进展以及骨关节疾病发病率的增加,人们对于骨修复医用金属材料的需求日益增多.生物医用金属材料包括不可降解钛及可降解金属镁和铁.金属材料在耐蚀性及骨整合方面存在一些不足,有必要对其表面改性进一步优化.锶元素具有促进成骨抑制破骨的作用,将其用作改性成分对提高医用金属表面骨细胞活性具有重要意义.本文主要对近年来医用金属钛、镁和铁表面掺锶涂层在耐蚀性和生物相容性方面进行了归纳及比较.重点介绍了锶与降解性、生物相容性好的载体(如羟基磷灰石、透钙磷石等)结合制备的复合涂层在钛合金、镁合金表面及铁合金表面提高骨整合性能的研究.最后,提出将锶元素与锌元素结合使得金属材料在促进骨修复的同时具有抗菌性能的建议.     

骨修复用生物玻璃复合材料研究进展

生物玻璃是一类性能优良的生物材料,具有良好的生物活性和生物相容性,作为骨修复植入体可以在材料界面与人体骨组织之间形成化学键合,诱导骨的修复与再生.将生物玻璃与其它材料进行复合,可以制备出生物活性和机械性能优良的骨修复复合材料.综述了生物玻璃复合材料的研究现状,并探讨了该类材料目前存在的不足,展望了其发展趋势.     

医用钛合金骨移植材料的研究现状

纯钛及钛合金以其优异的生物相容性、抗腐蚀性及与骨相近的弹性模量,在医学领域中获得了越来越广泛的应用.综述了医用钛合金骨移植材料的发展现状,并从抗磨损、耐腐蚀及生物活性3方面阐述了钛及其合金的表面改性技术.     

粉末烧结制备的生物医用多孔钛合金的力学性能

钛及钛合金由于具有优秀的抗腐蚀性、生物相容性、低密度和高的比强度等特性,而被应用于生物医学方面.然而,与人骨相比,钛合金的杨氏模量较高,可达100 GPa～110 GPa,而人骨的杨氏模量只有10 GPa～30 GPa.此外,人骨的拉伸强度、压缩强度和抗弯强度都比钛及钛合金低得多.这些力学性能上的差异使得植入件和骨的界面处成为体内负修复和骨治疗时的裂纹源.如果将钛及钛合金的杨氏模量降低到与人骨的相近,那么这些问题就不存在了.降低钛及钛合金的杨氏模量有2种途径:①是合金化;②是制备多孔材料.本研究将从这2点出发开发低模量的钛合金.     

钛氧膜生物相容性与生物活性的研究与应用

对钛氧膜的生物相容性和生物活性的研究及应用进行了评述.重点讨论了钛氧膜的制备方法、钛氧膜的活化处理方式以及钛氧膜在心血管材料和骨替代材料中的应用前景.     

Gender differences in publication productivity in psychology in India

An analysis of gender differences in psychology in India provides quantitative and qualitative assessment of R&D output contributed by psychologists with the indication of the trend of growth, skewness, relatedness, co-authorship pattern of productivity.     

Metrology in Chemistry in Germany

The system for Metrology in Chemistry in Germany is described. At the national standards level, a network of high-level chemistry institutes coordinated by the national metrology institute, PTB, provides the primary references for chemical measurements. A dissemination mechanism employs chemical calibration laboratories accredited within the framework of the German Calibration Service (DKD). They act as “multipliers” between the national standards level and the user level by providing the user with calibration means which are traceable to the SI via national standards. Traceability structures in clinical chemistry, electrochemistry, elemental analysis and gas analysis are described     

Natural radioactivity in drinking water in private wells in Finland

Natural radioactivity in drinking water was determined in population-based random study of 472 private wells. The mean concentrations of (222)Rn, (226)Ra, (234)U, (238)U, (210)Pb and (210)Po in drilled wells were 460, 0.05, 0.35, 0.26, 0.04 and 0.05 Bq l(-1), and in wells dug in the soil were 50, 0.016, 0.02, 0.015, 0.013 and 0.007 Bq l(-1), respectively. Approximately 10% of the drilled wells exceeded a radon concentration of 1000 Bq l(-1) and 18% a uranium concentration of 15 microg l(-1). The mean annual effective dose from natural radionuclides for a drilled well user was 0.4 mSv and 0.05 mSv for a user of a well dug in the soil. The effective dose arising from (222)Rn was 75% of the total of all natural radionuclides for drilled well users. As regards long-lived radionuclides, (210)Po and (210)Pb caused the largest portion of the effective dose. The dose arising from (238)U, (234)U and (226)Ra was only 8% of the total of all natural radionuclides.     

Natural radioactivity in drinking water in private wells in Finland

Radiation Protection Dosimetry     

Optische in situ Schichtdickenmessung in Bedampfungsanlagen. Optical in situ film thickness monitoring in coating systems

Optical film thickness monitoring is more precise than crystal monitoring. The optical measurement makes use of the fact that the intensity of a monochromatic light beam which is reflected on a film will change periodically with increasing film thickness. The measurement is performed at an exchangeable test glass that is positioned beside the substrates and is therefore coated in the same way as the substrates. The accuracy of cut‐off is achieved by a “fit” of a theoretical curve shape to the measured values. Order filters are used to ensure that, at a certain wavelength, higher deflection orders do not influence the measurement when a monochromator grating is used.     

Spanish experience in education and training in radiation protection in medicine

In most of its publications, the International Commission on Radiological Protection has highlighted the importance of education and training in radiation protection (RP) for medical exposures. Spain, like other Member States of the European Union, has implemented the Directive and the Guidelines in the medical area. The purpose of this paper is to present the Spanish experience in RP education and training in medicine, the different objectives established according to professional levels, existing regulations and feedback obtained from various RP actions.     

Differences in coagulation in clotting of vascular access in hemodialysis patients

Arteriovenous graft (AVG) thrombosis is a frequent cause of graft failure. We evaluated coagulation protein concentrations, platelet function, and viscoelasticity factors in 20 hemodialysis (HD) patients with AVGs. The goal was to determine whether significant differences in protein concentrations, platelet function, and viscoelasticity factors exist among dialysis patients requiring frequent AVG declot procedures vs. those who do not. Twenty HD patients were enrolled: 10 frequent clotters (>3 declots in the previous year) and 10 were nonclotters. Patients on antiplatelets or chronic anticoagulation were excluded. Laboratories were drawn pretreatment and heparinase was added to counteract any potential heparin effect. Coagulation protein concentrations including tissue factor (TF), thrombin/antithrombin III complex (TAT), and prothrombin fragment 1 + 2 (F₁₊₂) were assayed. The time to clot onset was measured by force onset time (FOT). Platelet contractile force (PCF) measured the force produced by platelets during clot retraction, whereas clot rigidity was measured as clot elastic modulus (CEM). FOT, CEM, and PCF were measured by Hemodyne. Both groups had upregulation of the TF pathway, as TF, TAT, and F₁₊₂ levels were similarly increased over baseline levels. Hemodialysis patients with frequent AVG clotting had higher levels of both PCF and CEM compared with nonclotters. Additionally, the frequent clotters had a lower FOT relative to nonclotters, although both were considered in the normal range. Our study suggests that HD patients with recurrent AVG thrombotic events form clots with higher tensile strength compared with HD patients without recurrent graft thrombosis.