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Skjöldebrand C, Tipper JL, Hatto P, Bryant M, Hall RM, Persson C. Current status and future potential of wear-resistant coatings and articulating surfaces for hip and knee implants. Mater Today Bio 2022; 15:100270. [PMID: 35601891 PMCID: PMC9118168 DOI: 10.1016/j.mtbio.2022.100270] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 04/09/2022] [Accepted: 04/24/2022] [Indexed: 10/29/2022] Open
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Ankha MDVEA, Silva ADM, Prado RFD, Camalionte MP, Vasconcellos LMRD, Radi PA, Silva Sobrinho ASD, Vieira L, Carvalho YR. Effect of DLC Films with and without Silver Nanoparticles Deposited On Titanium Alloy. Braz Dent J 2019; 30:607-616. [DOI: 10.1590/0103-6440201902708] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 06/24/2019] [Indexed: 11/22/2022] Open
Abstract
Abstract Diamond-like carbon (DLC) film is a biocompatible hard coating material that can prevent the leaching of metal ions. This study evaluates the structural characteristics of DLC, with and without silver nanoparticles, deposited by plasma (PECVD) on titanium alloy (Ti-6Al-4V) and bone formation in contact with DLC films. Sixty Ti-6Al-4V samples were used divided in: uncoated, coated with DLC and coated with DLC-Ag. After structural characterization, samples were fixed bilaterally at the rabbit's mandible. After 15 and 90 days, samples were characterized again and bone formation in the area was analyzed by histomorphometry. Statistical analysis was performed by two-way ANOVA. Both the DLC and DLC-Ag films were firmly adhered and showed a high electrical resistance without significant changes in the Raman spectrum after in vivo integration. After 15 days, there were immature bone trabeculae in the interface and partially covering the surface. After 90 days, mature bone filled the interface and coved the surface. There was no statistically significant difference among the three groups in both periods. In conclusion, osseointegration with DLC, DLC-Ag and uncoated Ti-6Al-4V is similar. However, DLC and DLC-Ag coverings have the advantage of electrical insulation and can presumably control bacterial activity and ion leaching.
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Affiliation(s)
| | | | | | | | | | - Polyana Alves Radi
- Universidade Estadual Paulista, Brazil; Universidade do Vale do Paraíba, Brazil
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Jelinek M, Kocourek T, Jurek K, Jelinek M, Smolková B, Uzhytchak M, Lunov O. Preliminary Study of Ge-DLC Nanocomposite Biomaterials Prepared by Laser Codeposition. NANOMATERIALS (BASEL, SWITZERLAND) 2019; 9:E451. [PMID: 30889797 PMCID: PMC6474194 DOI: 10.3390/nano9030451] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 03/09/2019] [Accepted: 03/13/2019] [Indexed: 02/07/2023]
Abstract
This paper deals with the synthesis and study of the properties of germanium-doped diamond-like carbon (DLC) films. For deposition of doped DLC films, hybrid laser technology was used. Using two deposition lasers, it was possible to arrange the dopant concentrations by varying the laser repetition rate. Doped films of Ge concentrations from 0 at.% to 12 at.% were prepared on Si (100) and fused silica (FS) substrates at room temperature. Film properties, such as growth rate, roughness, scanning electron microscopy (SEM) morphology, wavelength dependent X-ray spectroscopy (WDS) composition, VIS-near infrared (IR) transmittance, and biological properties (cytotoxicity, effects on cellular morphology, and ability to produce reactive oxygen species (ROS)) were studied in relation to codeposition conditions and dopant concentrations. The analysis showed that Ge-DLC films exhibit cytotoxicity for higher Ge doping.
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Affiliation(s)
- Miroslav Jelinek
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 21 Prague 8, Czech Republic.
- Faculty of Biomedical Engineering, Czech Technical University in Prague, nam. Sitna 3105, 27 201 Kladno, Czech Republic.
| | - Tomáš Kocourek
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 21 Prague 8, Czech Republic.
- Faculty of Biomedical Engineering, Czech Technical University in Prague, nam. Sitna 3105, 27 201 Kladno, Czech Republic.
| | - Karel Jurek
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 21 Prague 8, Czech Republic.
| | - Michal Jelinek
- Faculty of Nuclear Science and Physical Engineering, Czech Technical University in Prague, Brehova 7, 115 19 Prague 1, Czech Republic.
| | - Barbora Smolková
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 21 Prague 8, Czech Republic.
| | - Mariia Uzhytchak
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 21 Prague 8, Czech Republic.
| | - Oleg Lunov
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 21 Prague 8, Czech Republic.
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Pardo A, Ilic E, Thorwarth K, Stiefel M, Hauert R. Corrosion fatigue in DLC-coated articulating implants: an accelerated methodology to predict realistic interface lifetime. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2019; 20:173-186. [PMID: 30891104 PMCID: PMC6419647 DOI: 10.1080/14686996.2019.1580483] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 01/25/2019] [Accepted: 01/25/2019] [Indexed: 06/09/2023]
Abstract
We present a methodology to accelerate and estimate the lifetime of an interlayer under dynamic loading in body-like media. It is based on accelerating corrosion fatigue processes taking place at the buried interface of a Si-based adhesion-promoting interlayer in articulating implants on a CoCrMo biomedical alloy; the implants are coated with diamond-like carbon (DLC). The number of interface loading cycles to delamination is determined by reciprocal loading in corrosive fluid. Its dependence on the load is summarized in a Wöhler-like curve of a DLC/DLC-Si/CoCrMo system in body working conditions: cyclic stresses at 37 °C in phosphate buffered saline (PBS). The presence of oxygen as a contaminant strongly affects the lifetime of the interface under corrosion fatigue. The main parameters acting on the prediction, with a special emphasis on simulated in vivo conditions, are analyzed and discussed: the media (PBS, Milli-Q water, NaCl, Ringers' solution and bovine calf serum), the load, the frequency and the composition of the interface determined by X-ray photoelectron spectroscopy.
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Affiliation(s)
- Ainhoa Pardo
- Laboratory for Joining Technologies and Corrosion, Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-Dübendorf, Switzerland
| | - Emilija Ilic
- Laboratory for Joining Technologies and Corrosion, Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-Dübendorf, Switzerland
| | - Kerstin Thorwarth
- Laboratory for Nanoscaled Materials Science, Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-Dübendorf, Switzerland
| | - Michael Stiefel
- Laboratory for Transport at Nanoscale Interfaces, Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-Dübendorf, Switzerland
| | - Roland Hauert
- Laboratory for Joining Technologies and Corrosion, Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-Dübendorf, Switzerland
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Li SS, Wu BJ, Deng QY, Guo YB, Leng YX, Huang N. In vitro cytotoxicity evaluation of nano-carbon particles with different sp 2/sp 3 ratios. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2017; 75:854-862. [PMID: 28415539 DOI: 10.1016/j.msec.2017.02.077] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2016] [Revised: 12/18/2016] [Accepted: 02/14/2017] [Indexed: 12/22/2022]
Abstract
Graphitization occurs during the long-term service of a diamond-like carbon (DLC) modified artificial joint. Then, DLC wear debris, which are carbon particles with different sp2/sp3 ratios and sizes ranging from the nano- to micro-meter scale produced. In this paper, to promote the application of DLC coating for artificial joint modification, the cytotoxicity of DLC debris (nano-carbon particles, NCs) with different sp2/sp3 ratios was studied. The microstructure and physical characteristics of NCs with different sp2/sp3 ratios were investigated by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Transmission Electron Microscope (TEM) and Dynamic Light Scattering (DLS). Meanwhile, osteoblasts and macrophages were applied to characterize the cytotoxicity of the NCs. In vitro cytotoxicity assay results indicated that cells incubated with NCs of different sp2/sp3 ratios had greater osteogenic capacity, and these particles caused a weaker immune response in comparison with CoCrMo particles. Taken together, the results indicated that NCs with different sp2/sp3 ratios presented a good cytocompatibility than CoCrMo particles. But no significant differences were observed among NCs with different sp2/sp3 ratios. The better cytocompatibility of NCs is mainly attributable to their surface charge.
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Affiliation(s)
- S S Li
- Key Laboratory for Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, China
| | - B J Wu
- Key Laboratory for Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, China
| | - Q Y Deng
- Key Laboratory for Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, China
| | - Y B Guo
- The Third People's Hospital of Chengdu, Sichuan 610031, China
| | - Y X Leng
- Key Laboratory for Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, China.
| | - N Huang
- Key Laboratory for Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, China
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Liang Y, Liu DG, Bai WQ, Tu JP. Investigation of silicon carbon nitride nanocomposite films as a wear resistant layer in vitro and in vivo for joint replacement applications. Colloids Surf B Biointerfaces 2017; 153:41-51. [PMID: 28213286 DOI: 10.1016/j.colsurfb.2017.02.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 02/04/2017] [Accepted: 02/08/2017] [Indexed: 01/27/2023]
Abstract
Silicon-contained CNx nanocomposite films were prepared using the ion beam assisted magnetron sputtering under different nitrogen gas pressure. With increase of the nitrogen pressure, silicon and nitrogen content of the CNx films drastically increase, and is saturated as the PN2 reach about 40%. Surface roughness and the contact angle are increase, while the friction coefficient decreased. The CNx film with 5.7at.% Si content possess the lowest friction coefficient of only 0.07, and exhibited the best tribological properties. The impact of CNx films with different silicon content on the growth and the activation of osteoblasts were compared to that of Ti6Al4V. The incorporation of silicon in the CNx film also showed an increase cell adhesion. Bonding structure and surface energy were determined to be the factors contributing to the improved biocompatibility. Macrophages attached to 5.7at.% Si contained CNx films down regulated their production of cytokines and chemokines. Moreover, employed with Si contained CNx coated joint replacements, which were implanted subcutaneously into Sprague-Dawley mice for up to 36days, the tissue reaction and capsule formation was significantly decreased compared to that of Ti6Al4V. A mouse implantation study demonstrated the excellent in vivo biocompatibility and functional reliability of wear resist layer for joint replacements with a Si doped a-CNx coating for 36days.
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Affiliation(s)
- Y Liang
- Center of Medical Device Adverse Events Monitoring of Anhui, Center for Adverse Drug Reaction Monitoring of Anhui, Hefei 230031, China
| | - D G Liu
- Institute of Industry and Equipment Technology, School of Materials Science and Engineering, Hefei University of Technology, Hefei 230099, China; Center of Composite Material and Surface Treatment, China Electronic Technology Group Corporation No. 38 Research Institute (CETC 38), Hefei 230088, China.
| | - W Q Bai
- State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - J P Tu
- State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
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Song J, Liu Y, Liao Z, Wang S, Tyagi R, Liu W. Wear studies on ZrO 2 -filled PEEK as coating bearing materials for artificial cervical discs of Ti6Al4V. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2016; 69:985-94. [DOI: 10.1016/j.msec.2016.08.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Revised: 07/15/2016] [Accepted: 08/02/2016] [Indexed: 10/21/2022]
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Zhao GH, Aune RE, Espallargas N. Tribocorrosion studies of metallic biomaterials: The effect of plasma nitriding and DLC surface modifications. J Mech Behav Biomed Mater 2016; 63:100-114. [DOI: 10.1016/j.jmbbm.2016.06.014] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 04/14/2016] [Accepted: 06/11/2016] [Indexed: 10/21/2022]
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Gorzelanny C, Kmeth R, Obermeier A, Bauer AT, Halter N, Kümpel K, Schneider MF, Wixforth A, Gollwitzer H, Burgkart R, Stritzker B, Schneider SW. Silver nanoparticle-enriched diamond-like carbon implant modification as a mammalian cell compatible surface with antimicrobial properties. Sci Rep 2016; 6:22849. [PMID: 26955791 PMCID: PMC4783782 DOI: 10.1038/srep22849] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 02/23/2016] [Indexed: 02/06/2023] Open
Abstract
The implant-bone interface is the scene of competition between microorganisms and distinct types of tissue cells. In the past, various strategies have been followed to support bony integration and to prevent bacterial implant-associated infections. In the present study we investigated the biological properties of diamond-like carbon (DLC) surfaces containing silver nanoparticles. DLC is a promising material for the modification of medical implants providing high mechanical and chemical stability and a high degree of biocompatibility. DLC surface modifications with varying silver concentrations were generated on medical-grade titanium discs, using plasma immersion ion implantation-induced densification of silver nanoparticle-containing polyvinylpyrrolidone polymer solutions. Immersion of implants in aqueous liquids resulted in a rapid silver release reducing the growth of surface-bound and planktonic Staphylococcus aureus and Staphylococcus epidermidis. Due to the fast and transient release of silver ions from the modified implants, the surfaces became biocompatible, ensuring growth of mammalian cells. Human endothelial cells retained their cellular differentiation as indicated by the intracellular formation of Weibel-Palade bodies and a high responsiveness towards histamine. Our findings indicate that the integration of silver nanoparticles into DLC prevents bacterial colonization due to a fast initial release of silver ions, facilitating the growth of silver susceptible mammalian cells subsequently.
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Affiliation(s)
- Christian Gorzelanny
- Experimental Dermatology, Department of Dermatology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Ralf Kmeth
- Experimental Physics IV, Physics Institute, Augsburg University, Augsburg, Germany
| | - Andreas Obermeier
- Clinic of Orthopedics and Traumatology, Technical University Munich, 81675 Munich, Germany
| | - Alexander T Bauer
- Experimental Dermatology, Department of Dermatology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Natalia Halter
- Experimental Dermatology, Department of Dermatology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Katharina Kümpel
- Clinic of Orthopedics and Traumatology, Technical University Munich, 81675 Munich, Germany
| | | | - Achim Wixforth
- Experimental Physics I, Physics Institute, Augsburg University, Augsburg, Germany.,Augsburg Center for Innovative Technologies, Augsburg, Germany
| | - Hans Gollwitzer
- Clinic of Orthopedics and Traumatology, Technical University Munich, 81675 Munich, Germany
| | - Rainer Burgkart
- Clinic of Orthopedics and Traumatology, Technical University Munich, 81675 Munich, Germany
| | - Bernd Stritzker
- Experimental Physics IV, Physics Institute, Augsburg University, Augsburg, Germany
| | - Stefan W Schneider
- Experimental Dermatology, Department of Dermatology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
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Abstract
This chapter examines the importance of surface characteristics such as microstructure, composition, crystallographic texture, and surface free energy in achieving desired biocompatibility and tribological properties thereby improving in vivo life of artificial articulating implants. Current implants often fail prematurely due to inadequate mechanical, tribological, biocompatibility, and osseointegration properties, apart from issues related to design and surgical procedures. For long-term in vivo stability, artificial implants intended for articulating joint replacement must exhibit long-term stable articulation surface without stimulating undesirable in vivo effects. Since the implant's surface plays a vital and decisive role in their response to biological environment, and vice versa, surface modification of implants assumes a significant importance. Therefore, overview on important surface modification techniques, their capabilities, properties of modified surfaces/implants are presented in the chapter. The clinical performance of surface modified implants and new surfaces for potential next-generation articulating implant applications are discussed at the end.
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Affiliation(s)
| | - Mitun Das
- CSIR-Central Glass and Ceramic Research Institute, India
| | - Someswar Datta
- CSIR-Central Glass and Ceramic Research Institute, India
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Adsorption of bovine serum albumin on Zr co-sputtered a-C(:H) films: Implication on wear behaviour. J Mech Behav Biomed Mater 2014; 39:316-27. [DOI: 10.1016/j.jmbbm.2014.08.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 07/30/2014] [Accepted: 08/03/2014] [Indexed: 11/21/2022]
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On interlayer stability and high-cycle simulator performance of diamond-like carbon layers for articulating joint replacements. Int J Mol Sci 2014; 15:10527-40. [PMID: 24921709 PMCID: PMC4100166 DOI: 10.3390/ijms150610527] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 04/29/2014] [Accepted: 05/20/2014] [Indexed: 11/25/2022] Open
Abstract
Diamond like carbon (DLC) coatings have been proven to be an excellent choice for wear reduction in many technical applications. However, for successful adaption to the orthopaedic field, layer performance, stability and adhesion in physiologically relevant setups are crucial and not consistently investigated. In vitro wear testing as well as adequate corrosion tests of interfaces and interlayers are of great importance to verify the long term stability of DLC coated load bearing implants in the human body. DLC coatings were deposited on articulating lumbar spinal disks made of CoCr28Mo6 biomedical implant alloy using a plasma-activated chemical vapor deposition (PACVD) process. As an adhesion promoting interlayer, tantalum films were deposited by magnetron sputtering. Wear tests of coated and uncoated implants were performed in physiological solution up to a maximum of 101 million articulation cycles with an amplitude of ±2° and −3/+6° in successive intervals at a preload of 1200 N. The implants were characterized by gravimetry, inductively coupled plasma optical emission spectrometry (ICP-OES) and cross section scanning electron microscopy (SEM) analysis. It is shown that DLC coated surfaces with uncontaminated tantalum interlayers perform very well and no corrosive or mechanical failure could be observed. This also holds true in tests featuring overload and third-body wear by cortical bone chips present in the bearing pairs. Regarding the interlayer tolerance towards interlayer contamination (oxygen), limits for initiation of potential failure modes were established. It was found that mechanical failure is the most critical aspect and this mode is hypothetically linked to the α-β tantalum phase switch induced by increasing oxygen levels as observed by X-ray diffraction (XRD). It is concluded that DLC coatings are a feasible candidate for near zero wear articulations on implants, potentially even surpassing the performance of ceramic vs. ceramic.
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The Effect of Bias Voltage and Gas Pressure on the Structure, Adhesion and Wear Behavior of Diamond Like Carbon (DLC) Coatings With Si Interlayers. COATINGS 2014. [DOI: 10.3390/coatings4020214] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Hauert R, Falub CV, Thorwarth G, Thorwarth K, Affolter C, Stiefel M, Podleska LE, Taeger G. Retrospective lifetime estimation of failed and explanted diamond-like carbon coated hip joint balls. Acta Biomater 2012; 8:3170-6. [PMID: 22521966 DOI: 10.1016/j.actbio.2012.04.016] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Revised: 04/05/2012] [Accepted: 04/10/2012] [Indexed: 11/16/2022]
Abstract
Diamond-like carbon (DLC) coatings are known to have extremely low wear in many technical applications. The application of DLC as a coating has aimed at lowering wear and to preventing wear particle-induced osteolysis in artificial hip joints. In a medical study femoral heads coated with diamond-like amorphous carbon, a subgroup of DLC, articulating against polyethylene cups were implanted between 1993 and 1995. Within 8.5 years about half of the hip joints had to be revised due to aseptic loosening. The explanted femoral heads showed many spots of local coating delamination. Several of these explanted coated TiAlV femoral heads have been analyzed to investigate the reason for this failure. Raman analysis and X-ray photoelectron spectroscopy (XPS) depth profiling showed that the coating consists of diamond-like amorphous carbon, several Si-doped layers and an adhesion-promoting Si interlayer. Focused ion beam (FIB) transverse cuts revealed that the delamination of the coatings is caused by in vivo corrosion of the Si interlayer. Using a delamination test set-up dissolution of the silicon adhesion-promoting interlayer at a speed of more than 100 μm year(-1) was measured in vitro in solutions containing proteins. Although proteins are not directly involved in the corrosion reactions, they can block existing small cracks and crevices under the coating, hindering the exchange of liquid. This results in a build-up of crevice corrosion conditions in the crack, causing a slow dissolution of the Si interlayer.
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Affiliation(s)
- R Hauert
- Empa, Swiss Federal Laboratories for Materials Testing and Research, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland.
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