Change search
Refine search result
12 1 - 50 of 73
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Almeida, Nuno A.F.
    et al.
    Mechanical Engineering Department & TEMA, University of Aveiro, Campus Universitário de Santiago.
    Rodrigues, Joana
    Physics Department & I3N, University of Aveiro, Campus Universitário de Santiago.
    Silva, Patricia
    Mechanical Engineering Department & TEMA, University of Aveiro, Campus Universitário de Santiago.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Soares, Manuel J.
    Physics Department & I3N, University of Aveiro, Campus Universitário de Santiago.
    Monteiro, Teresa
    Physics Department & I3N, University of Aveiro, Campus Universitário de Santiago.
    Lopes-da-Silva, José A.
    Chemistry Department & QOPNA, University of Aveiro, Campus Universitário de Santiago.
    Marques, Paula A.A.P.
    Mechanical Engineering Department & TEMA, University of Aveiro, Campus Universitário de Santiago.
    Pressure dependent luminescence in titanium dioxide particles modified with europium ions2016In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 234, p. 137-144Article in journal (Refereed)
    Abstract [en]

    Particles of titanium dioxide were prepared in the presence of europium ions (TiO2:Eu) by a solvothermal method and thermal annealed in air at 500 °C. The spectroscopic properties of TiO2:Eu particles were analyzed indicating that the Eu3+ ions are likely distributed at the surface or near the surface of the titanium dioxide particles. The photoluminescence analysis showed that the intraionic emission was strongly sensitive to reduced pressure conditions, as seen by its absence under vacuum conditions. The ion emission was re-established as soon as the atmosphere was restored. Additionally, the ion integrated emission intensity follows a linearly dependence with pressure in the range of 150 to 800 mbar revealing a high sensitivity to small variations in pressure, which is an unprecedented result. This innovation will allow the study of new technologies in the area of low vacuum sensors where TiO2:Eu may act as the active element of an optical sensor for a pressure device.

  • 2.
    Coelho, Margarida
    et al.
    Department of Mechanical Engineering, University of Aveiro.
    Torrao, Guilhermina
    Department of Mechanical Engineering, University of Aveiro.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Gracio, Jose
    Department of Mechanical Engineering, University of Aveiro.
    Nanotechnology in automotive industry: research strategy and trends for the future – small objects, big impacts2012In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 12, no 8, p. 6621-6630Article in journal (Refereed)
    Abstract [en]

    The goal of this paper is to emphasize and present briefly the nanotechnology science and its potential impact on the automotive industry in order to improve the production of recent models with an optimization of the safety performance and a reduction in the environmental impacts. Nanomaterials can be applied in car bodies as light weight constructions without compromising the stiffness and crashwortiness, which means less material and less fuel consumption. This paper outlines the progress of nanotechnology applications into the safety features of more recent vehicle models and fuel efficiency, but also emphasis the importance of sustainable development on the application of these technologies and life cycle analysis of the considered materials, in order to meet the society trends and customers demands to improve ecology, safety and comfort.

  • 3.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Biointerface characterization of metal on metal implant materials using XPS and ToF-SIMS: comparison of human serum, synovial fluid, MEM and water2008Conference paper (Other academic)
  • 4.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Biomaterials and biotribology2009In: Thule: Kungl. Skytteanska samfundets årsbok 2009, Umeå: Kungl. Skytteanska samfundet , 2009, p. 117-127Chapter in book (Other (popular science, discussion, etc.))
  • 5.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Effect of light power density variation on dental light-cure resin composites2001Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Dental resin based composites are tooth-colored filling materials composed of synthetic resins and particulate ceramic reinforcing filler particles. The resin system also contains molecules that promote and/or modify the polymerisation reaction of the dimethacrylate resin monomers. The filler is bonded to the cured polymer with a film of silane coupling agent covering the filler particles. That silane film is also bonded to the reinforcing filler particles. Dental composites have been used as restorative materials for anterior applications since the 60s. Their tooth matching ability, ability to bond to tooth tissues and their lack of mercury have also promoted them as an alternative to dental amalgam for use in posterior teeth. Favourable results from long-term clinical trails demonstrate that when placed correctly, composites can produce esthetical posterior restorations with acceptable longevity ( el-Mowafy et al., 1994: Taylor et al., 1994 ), although not yet comparable to amalgams (Mjor). Significant problems still remain to be solved and limit their usefulness in the routine practice of dentistry. One of the most significant problems today relates to large material contraction during intra-oral polymerisation of composites. The hardening of composites is the result of polymerisation reactions involving dimethacrylate monomers. A rigid and heavily cross-linked polymer network is produced which surrounds the inert filler particles. The extent of this reaction, the degree of conversion, dictates many of the physical and mechanical properties of the composites. The degree of cure is influenced by many factors, including the light energy used to activate the reaction (Rueggeberg and Jordan, 1993). A reduction in volume, here termed shrinkage, occurs when the monomer polymerises. That shrinkage, which is more than 10-20 times higher in microns than what occurs when an amalgam sets, is caused by a change from van der Waal bonding to covalent bond formation. During that reaction, the monomer molecules rearrange and move closer together (Oleinik, 1986). The magnitude of the shrinkage is dictated by the extent of the reaction, as well as by the nature of the monomers. Research program In the currently ongoing study we are studying the effect of light intensity on polymerisation-induced strain, degree of conversion, volumetric changes and modulus of elasticity of two commercial dental composites. The objective is to test the hypothesis that low light intensity and increased curing time can be used to cure composites with better performance than high intensity cured composites. The benefits with the low intensity long time cure could be improved marginal integrity without loss of mechanical and physical properties. MethodsPolymerisation strain: Small ring shape samples were prepared and cured with three different light intensities (800, 450 and 200 mW/cm2). The polymerisation strain was measured by strain gages. The temperature increase was also measured. The sources of increased temperature are heat generated from the lamp as well as exothermal heat from curing. Volumetric shrinkage: The overall volumetric shrinkage was measured using water and mercury displacement methods. Degree of conversion: The effect of light intensity irradiation time on degree of conversion was measured by spectroscopy (FT- Raman). Modulus of Elasticity: One important factor influencing residual stresses is the stiffness of the dental composite. A miniature tensile machine for small sample size was used to measure the Young's modulus for two materials cured with different light intensities. ResultsA decrease in light intensity decreased the residual strain for the different material systems being evaluated. As long as the lower light intensity was compensated with an increased curing time, degree of conversion, Young's modulus and volumetric shrinkage were compared to high intensity cure for shorter time. The temperature increase, though, was lower for the low intensity cure than for the high intensity cure, even if longer time was used for the low intensity cure. DiscussionThe above results support the proposed hypothesis. A lower light intensity delays gelation, allowing the material to flow more initially. Such flow decreases the induced strain. Another important factor is the lower increase in temperature, which also decreases the thermal shrinkage that occurs during cooling back to room temperature. Differences between the two materials can also be related to differences in molecular structures between the two composites. An important conclusion is that for these materials, the polymerisation reaction is controlled by the total light energy supplied to the dental composite.

  • 6.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Manufacturing of bionano-composite: CNT reinforced UHMWPE composite2007Conference paper (Other academic)
  • 7.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Reactivity of XPS Ion-etched CoCrMo and TiAlV alloys in physiological medium2009Conference paper (Other academic)
    Abstract [en]

    Introduction: Osteolysis induced by wear particles in metal-on-polyethylene hip implants has been the key motivation to look for alternative bearings and in fact emergence and development of new metal-on-metal (MOM) implant materials for joint replacement. However, while the volume of wear particles produced in metal-on-metal articulations is lower in MOM implants, it is clear that the smaller size of the metal wear particles has a dramatic effect on the number of particles produced per unit volume of wear. Although various surface and interface characterization methods have been applied to study the physical wear, corrosion and implant surface interactions with biological environments, presently the local and systematic effects of metal debris in body are poorly understood. Materials and Methods: Cobalt-chromium-molybdenium (CoCr) and titanium-aluminum-vanadium (TiAlV) alloys have been used in MOM implants extensively. Metallic samples were cut and mirror polished. In the present study the samples were immersed in four different biological lubricants (Human serum, synovial fluid and MEM) for 10 min, 1 hr, and 5 days of immersion and then studied by X-ray Photoelectron Spectroscopy (XPS) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). XPS determined the chemistry of elements located whit in the top few nanometers of materials. Significant differences in the absorbed layers and differences in the corrosive nature of CoCr implant substrates immersed in different media were found. Results and discussion: Spectra from P2p3/2, O1s, Ca2p3/2, C1s and N1s were collected. Metallic substrates behaved differently when immersed in the same lubricant for different time intervals. The three lubricants reacted different with metallic surfaces. Larger calcium deposits occurred in supersaturated physiological solutions. Deposition of calcium phosphate was different on CoCr and TiAlValloys depending on the lubricant and the immersion period. Specimens immersed into synovial fluid gave thinner oxide layers and lower calcium phosphate deposits. For all specimens, water immersion resulted in thicker oxide layer. Conclusion: Passivation of the metal surface is fundamental to corrosion resistance where a metallic oxide (like chromium oxide) barrier protects the underlying metal from further corrosion. The amount and purity of the oxide layer on immersed specimens depends on the density and thickness of the overlying deposits of calcium phosphate (Figure 1), proteins and other adsorbed molecules, as well the contaminations. The ration of Cr2O3 to Cr was calculated for CrCo alloy and was related to the thickness and/or concentration of the oxide in different lubricants. The lower calcium phosphate deposit in synovial fluid might be due to the present of components such as GAG and associated proteins, which stop the calcium deposition due to the circulation of the fluid in the effective joint space. ToF-SIMS measurements showed that the resulting corrosion products depend upon the nature of the environment. The thickness of the calcium phosphate deposits was different for different metal substrate.

  • 8.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Variables affecting stress development and resin conversion in light-cured dental composites2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The general aim of this dissertation was to identify and investigate factors that can be used to minimize stress development in light cured dental resins without compromising the conversion level of the polymer. Modulus of elasticity, polymerization contraction strain, degree of conversion and shrinkage of light-cure dental composites were determined after curing with three different light power densities where total irradiated energy (J/cm2) kept constant. FT-Raman spectroscopy was employed to determine the degree of conversion. The cure kinetic of light cured resins was studied by use of photocalorimetry (photo-DSC). Dynamic mechanical thermal (DMTA) analysis was used to investigate how different light curing methods affected glass transition and tangent delta of light curable dental resins when the temperature changed from 0 to 200°C. Optical properties of dental composites were studied. Three different filler types, two different surface treatments and eight different filler fractions per filler type and surface treatment were investigated. Light transmission was measured for the different composite compositions at sample thicknesses of 1 to 5 mm by use of a universal power meter. As long as the total light energy remained the same, the modulus of elasticity remained constant for each composite, even though the power density differed. Composite thickness, irradiance time, composition of the light cure composite and irradiation value had significant impact on degree of conversion. The irradiance value did not significantly affect on the transition temperature value. Initiator, co-initiators and light irradiance value had all significant impact on cure behavior. Different filler types and filler surface treatments had significant effects on light absorption. In general, light absorption increased linearly with filler fraction and sample thickness of the cured composites. Conclusion: Low rather than high light irradiance values decrease stress levels in composites, and comparable conversion levels are reached as long as the total light energy value remains the same for low versus high irradiance. By increasing the composite thickness above 2 mm but not exceeding 6 mm, energy levels exceeding 30 J are needed to achieve acceptable levels of degree of conversion. Different irradiance values do not affect the final Tg of tested composites as long as the total light energy remains the same. By using appropriate photo initiator/co-initiator combination and soft-start curing it is possible to achieve slow curing and high DC within a 40 s. As expected, different filler particle properties have significant effects on light absorption during curing making it important to consider these differences when one tries to develop a general light curing strategy for light curable dental resins.

  • 9.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Enqvist, Evelina
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Grácio, José
    Nanotechnology Research Division, University of Aveiro.
    Gonçalves, Gil
    Nanotechnology Research Division, University of Aveiro.
    Marques, Paula
    Nanotechnology Research Division, University of Aveiro.
    Biotribolological behaviour of reinforced UHMWPE2010Conference paper (Other academic)
    Abstract [en]

    Carbon nanoforms exhibit exceptional physical and chemical properties due to their nano-scale dimensions. They also have very high aspect ratio which makes them an excellent reinforcement material for polymer composites. Hydroxyapatite (HA) is the prime constituent of bone generation because of its ability to bond chemically with living bone tissues and positively affect the osteoblasts; this is due to its similar chemical composition and crystal structure to apatite in the human skeletal system. Ultra high molecular weight polyethylene (UHMWPE) is already used as implant material in high stress bearing areas such as hip and knee prosthesis. Wear debris of ultra high molecular weight polyethylene cause osteolysis which is a major reason of long-term failure of total hip replacements. In this study carbon nanoforms together with hydroxyapatite (HA) nanoparticles were used as reinforcement in UHMWPE matrix in order to produce high strength and wear resistant biocomposite with better bioactivity character. Solvent casting and melt blending methods were used during the preparation of this bio-nano composite. The manufacturing process was studied using different characterization methods such as diferencial scanning calorimetry (DSC), scanning electron microscopy (SEM) and Raman-spectroscopy. The tribological behaviour of the manufactured bio-nano composite was studied using pin-on-plate method. Wear and friction of the produced novel composite were studied in different biological lubrications. Different lubrication affected the friction rate and wear, though the results were not statistically different. The reinforced UHMWPE showed superior tribology behaviour in comparison to pure UHMWPE (p>0.05).

  • 10.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Enqvist, Evelina
    Larsson, Roland
    Gracio, José
    University of Aveiro.
    Kumar, Sunil
    University of South Australia.
    Friction, wear and surface characterization of metal-on-metal implant in protein rich lubrications2010In: 14th Nordic Symposium on Tribology: NORDTRIB 2010 : Storforsen, Sweden, June 8-11, 2010, Luleå: Luleå tekniska universitet, 2010Conference paper (Refereed)
    Abstract [en]

    Although various surface and interface characterization methods have been applied to study the physical wear, corrosion and implant surface interactions with biological environments, presently - in metal on metal (MOM) hip implant- the local and systematic effects of interaction between metal surfaces and protein rich lubrication in body are poorly understood. Materials and Methods: Cobalt-chromium-molybdenium (CoCrMo) alloys have been used in MOM implants extensively. In the present study the samples were immersed in four different biological lubricants (Human serum, synovial fluid, MEM and distill water) for 10 min, 1 hr, and 5 days of immersion and then studied by X-ray Photoelectron Spectroscopy (XPS) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). XPS determined the chemistry of elements located whit in the top few nanometers of materials. Friction and wear behavior of CoCrMo substrate in different biological lubricatin were also studied. Results and discussion: Spectra from P2p3/2, O1s, Ca2p3/2, C1s and N1s were collected. Metallic substrates behaved differently when immersed in the same lubricant for different time intervals. The four lubricants reacted differently with metallic surfaces. Larger calcium deposits occurred in supersaturated physiological solutions. Deposition of calcium phosphate was different on CoCrMo alloys depending on the lubricant and the immersion period. Specimens immersed in synovial fluid gave thinner oxide layers and lower calcium phosphate deposits. For all specimens, water immersion resulted in thicker oxide layer. Synovial fluid gave lowest coefficient of friction when distill water gave the highest value. Generally wear was higher for disc in comparison to the pin (in the pin on plate test).

  • 11.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Fernberg, Patrik
    Evaluation of manufacturing schemes for carbon nanotube doped epoxy resins and composites2005Report (Other academic)
  • 12.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Griesser, H.
    Ian Wark Research Institute, University of South Australia.
    Biotribocorrosion: time dependence of the surface chemistry of metal-on-metal implants in biological environment2009In: 8th World Biomaterials Congress 2008: Amsterdam, the Netherlands, 28 May - 1 June 2008 ; [WBC 2008], Red Hook, NY: Curran Associates, Inc., 2009, Vol. 4, p. 1978-Conference paper (Refereed)
  • 13.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, Roland
    Höglund, Erik
    Biotribology: surface chemistry characterization of metal-on-metal implants in rich environment2008In: Proceedings of NORDTRIB 2008, 13th Nordic Symposium on Tribology: Scandic Rosendahl Hotel, Tampere, Finland, June 10 - 13, 2008 / [ed] Jaakko Kleemola; Arto Lehtovaara, Tampere: Tampere University of Technology, 2008Conference paper (Refereed)
    Abstract [en]

    Introduction: Osteolysis induced by wear particles in metal-on-polyethylene hip implants has been the key motivation to look for alternative bearings and in fact emergence and development of new metal-on-metal (MOM) implant materials for joint replacement. However, while the volume of wear particles produced in metal-on-metal articulations is lower the number of particles produced is higher per volume of wear, due to the reduced size of wear particles. Although various surface and interface characterization methods have been applied to study the physical wear, corrosion and implant surface interactions with biological environments, presently the local and systematic effects of metal debris are poorly understood. Materials and Methods: Cobalt-chromium-molybdenium (CoCr) alloys have been used in MOM implants extensively. Metallic samples were cut and mirror polished. In the present study The samples were immersed in four different biological lubricants (Human serum, synovial fluid, MEM and Milli-Q water) for 10 min, 1 hr, and 5 days of immersion and then studied by X-ray Photoelectron Spectroscopy (XPS) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). XPS determined the chemistry of elements located whitin the top few nanometers of materials. Significant differences in the absorbed layers and differences in the corrosive nature of Ti and CoCr implant substrates and wear particles were found. Results and discussion: Spectra from P 2p3/2, O1s, Ca2p3/2, C1s and N1s were collected. Metallic substrates behaved differently when immersed in the same lubricant. The four lubricants reacted different with metallic surfaces. Larger calcium deposits occurred in supersaturated physiological solutions. Deposition of calcium phosphate was different on CoCr alloys depending on the lubricant and the immersion period. Specimens immersed into synovial fluid gave thinner oxide layers and lower calcium phosphate deposits. For all specimens, water immersion resulted in thicker oxide layer. For many reactive metals, dissolution of ions from the metal surface takes place along with thickening of the metal oxide during passivation, or surface corrosion.Conclusion: Glycoaminoglycans (GAG) and related proteins may hinder calcium phosphate deposition on samples immersed in synovial fluid. ToF-SIMS measurements showed that the resulting corrosion products depend upon the nature of the environment. The thickness of the calcium phosphate deposits was different for different metal substrate.

  • 14.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Lindberg, A.
    Umeå universitet.
    Dijken, J.W.V. van
    Umeå universitet.
    The effect of flow-composite on interfacial-chemistry and morphology of dentin/bonding2008Conference paper (Other academic)
    Abstract [en]

    Objectives: to study the interfacial bond of self-etching primer to coronal and root dentin with and without the use of flow composite. Methods: morphology, structural characteristics and interaction at the interfaces were studied with Raman micro-spectroscopy and SEM. Coronal (superficial) dentin and root (deep) dentin were prepared from eight non-carious extracted premolars. Immediately after extraction, teeth were carefully cleaned and stored in chlorhexidine digluconate solution prior to preparation. Smear-layer was generated by wet grinding with 600 grit silicon carbide polishing paper for 10 s. A self etching primer Xeno III (Dentsply) was applied according to manufacturer instruction. Half of the specimens were covered with a thin layer of Tetric flow (Ivoclar Vivadent) prior to curing. A 1mm slice was cut of the mesial and distal surface of the teeth with a low speed diamond saw to uncover the interfacial margins and hybrid layer. A modified Nakabayashi method, using HCl and HNO3 followed by NaOCl, was used to show the penetration depth of the monomers. SEM images from 750 to 6000 magnification were collected from dentin/bonding interfaces. Raman spectrums were collected at 1µm intervals across the dentin/bonding interface and provided chemical information. Degree of demineralization as function of depth was calculated. Results: No difference in degree of demineralization was seen between coronal and root dentin. It was slightly lower by using a thin layer of flow prior to curing. The thickness of the dentin/bonding hybrid layer was less for samples with flow and its morphology of hybrid layer and interfacial structure was significantly different. Conclusion: Flow composite had an undesirable affect on the physical-chemistry structure of dentin bonding with a self etching primer. HL and bonding tags morphology was significantly different by using flow composite. No significant different were observed between root and coronal dentin interfaces.

  • 15.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Marques, Paula
    University of Aveiro.
    Gracio, Jose
    University of Aveiro.
    Enqvist, Evelina
    Gonçalves, Gil
    University of Aveiro.
    Novel bio nano-composite for biomedical application2010In: 14th Nordic Symposium on Tribology: NORDTRIB 2010 : Storforsen, Sweden, June 8-11, 2010, Luleå: Luleå tekniska universitet, 2010Conference paper (Refereed)
    Abstract [en]

    Carbon nanoforms exhibit exceptional physical and chemical properties due to their nano-scale dimensions. They also have very high aspect ratio which makes them an excellent reinforcement material for polymer composites. Hydroxyapatite (HA) is the prime constituent of bone generation because of its ability to bond chemically with living bone tissues and positively affect the osteoblasts; this is due to its similar chemical composition and crystal structure to apatite in the human skeletal system. Ultra high molecular weight polyethylene (UHMWPE) is already used as implant material in high stress bearing areas such as hip and knee prosthesis. Wear debris of ultra high molecular weight polyethylene cause osteolysis which is a major reason of long-term failure of total hip replacements.In this study carbon nanoforms together with hydroxyapatite (HA) nanoparticles were used as reinforcement in UHMWPE matrix in order to produce high strength and wear resistant biocomposites with better bioactivity character. Solvent casting and melt blending methods was used during the preparation of this bio-nano composite. The phase compositions and the surface morphology of the nanocomposite material have been studied using X-ray diffraction (XRD), scanning electron microscopy (FE-SEM), and micro-Raman spectroscopy. Nanoindentation technique was used to determine the elastic modulus and hardness of the nanocomposites with different weight% of HA and carbonnanoforms concentrations. The tribologic behaviour of this nano composite was studied using pin-on-plate method. Wear and friction of the produced nano-composites were studied in different biological lubrications.

  • 16.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Nilsson, Greger
    SICOMP AB, Swedish Institute of Composites.
    Undersökning av rotstift av kompositmaterial2004Report (Other academic)
  • 17.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Ramanenka, Dmitrij
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Enqvist, Evelina
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Mechanical and thermal characterisation of novel UHMWPE-nano composite: A copmarrative study against virgin UHMWPE2012Conference paper (Refereed)
  • 18.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Sjödahl, Mikael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Söderholm, Karl-Johan M.
    University of Florida.
    How filler properties, filler fraction, sample thickness and light source affect light attenuation in particulate filled resin composites2005In: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 21, no 8, p. 721-730Article in journal (Refereed)
    Abstract [en]

    The way by which variables such as filler type, filler surface treatment and light source affect light attenuation in particulate filled resin composites was presented. Mixture of 50 wt% bisGMA and 50wt% TEGDMA consisting of a photo-initiatior and a co-initiator was prepared. Three different filler types, HBB, SBB, and KU, which were either silane surface treated or not, were added to that mixture in eight different volume percentage. It was observed that of the two light sources, more light was absorbed by the composite when the laser light was used. It was also observed that the HBB filler absorbed most light and the KU filler the least.

  • 19.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, K J
    University of Florida, Gainesville.
    Young's modulus and degree of conversion of different combination of light-cure dental resins2009In: Open Dentistry Journal, ISSN 1874-2106, E-ISSN 1874-2106, Vol. 3, p. 202-207Article in journal (Refereed)
    Abstract [en]

    Objectives: To evaluate Young's modulus and degree of conversion of several combinations of bisGMA,To evaluate Young's modulus and degree of conversion of several combinations of bisGMA, UEDMA, TEGDMA light-cure dental resin.Methods: Young's modulus and DC% were studied for 21 different resin combinations of bisGMA, TEGDMA and Young's modulus and DC% were studied for 21 different resin combinations of bisGMA, TEGDMA and UEDMA. Small universal testing machine and photo-calorimetry were used for the tests. The results were evaluated using ANOVA and Duncan's multiple range tests and regular t-test. Results: Young's modulus varied between 2.37±0.2 GPa (100% TEGDMA) and 4.15±0.2 GPa (100% bisGMA). By adding Young's modulus varied between 2.37±0.2 GPa (100% TEGDMA) and 4.15±0.2 GPa (100% bisGMA). By adding TEGDMA to bisGMA or UEDMA, the Young's modulus decreased significantly (p<0.05). Degree of conversion was significantly (p<0.05) higher when the wt% of TEGDMA was high in the mixtures than for highly concentrated bis-GMA (resin mixtures with TEGDMA in comparison to mixture with bisGMA had higher degree of conversion). DC% was significantly higher (p<0.05) for binary mixtures of UEDMA and TEGDMA, and significantly lower for 100 wt% bis-GMA´(p<0.05). The DC% values were between 53.1%±0.9% (100% bisGMA) and 85.6%±1% (80% UEDMA-20% TEGDMA). The concentration of bisGMA, in the monomer mixture, affected DC% and Young's modulus oppositely. Conclusions: The differences in the values for DC% were mostly justified by the differences in the molecular structures of The differences in the values for DC% were mostly justified by the differences in the molecular structures of the different monomers. It was also revealed that higher DC% does not always result in a higher Young's modulus, because molecular and network structural parameters play major roles in the final physical properties of the mixtures.

  • 20.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan
    Florida University.
    Cure kinetic behavior of light-cure dental composites2003Article in journal (Other academic)
    Abstract [en]

    Objective: To investigate differences in cure kinetic behaviours of different photo and co-initiator systems used in dental light-cure composites. Method: A resin system (50 wt.% of bisGMA and 50 wt.% of TEGDMA) was mixed with either campherquinone (CQ) or 1-phenyl-1,2-propanedione (PPD) as photo-initiator. N,N-dimethyl-p-aminobenzoic acid ethylester (DABE), N,N-cyanoethylmethylaniline (CEMA), N,N-diethanol-p-toluidine (DEPT) and 2-dimethylaminoethyl methacrylate (DMAEMA) were used as co-initiators respectively. Complex cure behaviour of 24 experimental mixtures made from 2 photoinitiators, 4 co-initiators, 3 curing light/time was studied with differential Scanning Calorimetery (DSC). Six specimens of each composition were cured either with 800 mW/cm2 for 40 s, soft start curing for 60 s or LED for 40 s. The DSC results were analysed using ANOVA and Duncan's multiple range test and regular t-test. Result: Rate of polymerisation was significantly (p<0.05) higher when materials were cured with 800 mW/cm2 compare to soft start and LED curing methods when the final degree of conversion values did not differ significantly (p>0.05). Compared to campherquinone, the photo-initiator PPD reduced the maximal DC% and rate of the polymerisation significantly (p<0.05). PPD was not a suitable photo-initiator when cured with LED since the blue spectra emitting from the used LED lamp does not cover the optimal activation wavelength for PPD properly. The highest DC% measured at the end of curing was for CQ & DABE 74%±1 cured with 800 mw/cm2 for 40s and the lowest was for PPD&DMAEMA 22%±1.1 when material was cured with LED for 40s. Use of DEPT resulted in significant decreases in degree of conversion (p<0.05). Conclusion: It was concluded that intrinsic slow cure might be obtained with certain compositions of photo & co-initiators and curing methods without impairing the final extent of degree polymerzation.

  • 21.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan
    University of Florida.
    How light irradiance and curing time affect monomer conversion in light-cured resin composites2003In: European Journal of Oral Sciences, ISSN 0909-8836, E-ISSN 1600-0722, Vol. 111, no 6, p. 536-542Article in journal (Refereed)
    Abstract [en]

    We tested the hypothesis that the degree of conversion of a light-cured dental composite relates to the calculated (s × mW cm-2 = mJ cm-2) rather than to the irradiance value (mW cm-2) of the light source. Two light-curable composite resins were cured with three different light irradiance values over different curing times. The specimens tested were 2, 4 or 6 mm thick, and the degree of conversion values were measured with Raman spectroscopy on the top and the bottom surfaces of the specimens. The highest conversion value of one of the materials was just below 60%, while the maximal conversion value of the other material was just below 65%. That difference in conversion values could be related to differences in monomer systems used in the two composites. By considering light energy per square centimeter (J cm-2) rather than light irradiance (mW cm-2), we found that equivalent energy values gave similar conversion values for a certain sample thickness. From these findings, we conclude that our experimental results support our hypothesis.

  • 22.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan
    Florida University.
    Berglund, Lars
    Kungliga tekniska högskolan, KTH.
    Effect of light intensities variations on bulk curing of dental composites2002In: Journal of Dental Research, ISSN 0022-0345, E-ISSN 1544-0591, Vol. 81, no Suppl. 1Article in journal (Refereed)
    Abstract [en]

    The light intensity used during curing of light curable dental composites is believed to affect the residual stress level. In this study we tested the hypothesis that low light intensity and long but clinically acceptable light curing time, can produce composites with physical/clinical properties (e.g. volumetric shrinkage, linear contraction stress, degree of conversion (DC%) and Young's modulus) comparable to those of high light intensity cured composites. Methods: Two dental composites, Z100 and Z250, were investigated. Specimens were cured with light intensities of 200, 450 and 800 mW/cm2 for 140, 60 and 35 s from a distance of 7 mm. Linear contraction strains were measured with strain-gages attached to stainless steel rings serving as molds (8 mm in diameter and 4 mm high). DC% was measured at the top and the bottom of samples as well through the bulk using FTIR. Volumetric polymerization shrinkage was determined using a water displacement method. Young's modulus was determined in tension on composite specimens with dimensions of 8 x 50 x 1 mm. Results: Polymerization stress level decreased significantly (p<0.05) when cured with 200 mW/cm2 rather than with 800 mW/cm2. Reduction in light intensity did not decrease the DC% values significantly, nevertheless the most dramatic differences existed between top and bottom surfaces (p<0.05) rather than among curing groups. Measured modulus and volumetric shrinkage values were no significantly different (p>0.05) between different light intensity groups. Conclusion: Low light intensity decreased the residual stress and DC% values (through the depth of cure) significantly (p<0.05), but did not significantly affect the Young's modulus and the volumetric shrinkage values. The lower residual stress values, reflected by lower strain levels in the metal rings used during measurement, suggest that more stress relaxation occurs in the low light intensity group during cure. Our results support the proposed hypothesis

  • 23.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan
    Florida University.
    Berglund, Lars
    Kungliga tekniska högskolan, KTH.
    Effect of light-intensity variations on bulk curing of dental composites2002In: Journal of Dental Research, ISSN 0022-0345, E-ISSN 1544-0591, Vol. 81, no Suppl 1Article in journal (Other academic)
  • 24.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan
    Florida University.
    Berglund, Lars
    How light-intensity and cure-time affect monomer conversion in light-cured composites2002In: Journal of Dental Research, ISSN 0022-0345, E-ISSN 1544-0591, Vol. 81, no Suppl 1Article in journal (Refereed)
  • 25.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan
    Florida University.
    Gren, Per
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Quantitative measurements of dental light beam (halogen versus LED)2005Conference paper (Other academic)
  • 26.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan M.
    Department of Dental Biomaterials, University of Florida.
    Dynamic mechanical thermal analysis of two light-cured dental composites2005In: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 21, no 10, p. 977-983Article in journal (Refereed)
    Abstract [en]

    ObjectivesClinical observations suggest that some composite resins are more often linked to post-operative sensitivity than others. These differences may relate to differences in modulus of elasticity and polymerization rates among materials. The aim of this study was to identify viscoelastic behavior of two light curable composites and determine whether significant differences in viscoelastic behavior exist between the two materials when light cured at each of three different irradiance values.MethodsTwo composites (Z100 and Z250 by 3M ESPE) were evaluated. Six specimens per composite and irradiance value (250, 500 and 850 mW/cm2) were made. The curing times were chosen to produce a fixed energy value of 30 J/cm2 independent of irradiation value. Dynamic mechanical thermal analysis (DMTA) was performed in single cantilever clamped mode.ResultsThere were significant differences in transition temperatures between the two materials and the three frequencies at their glass transition temperatures, while significant differences did not exist at the lower transitions. The glass transition of Z250 was lower and narrower than that of Z100. Z250 exhibited lower storage modulus values. The irradiance values did not affect any of the transition temperatures significantly.SignificanceThe lower and more distinct Tg of Z250 suggests that Z250 cures more efficiently than Z100. The lower storage modulus of Z250 suggests that Z250 develops less stress in the tooth than Z100 during curing if shrinkage is the same for the two materials. The findings suggest that the material chosen, rather than irradiance, determines the stress level developed during light curing.

  • 27.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan M.
    How degree of conversion and E-modulus of light-cure dental-resins interact2006In: 84th General Session and Exhibition of the IADR and 1st Meeting of the Pan-Asian-Pacific Federation: Brisbane Convention and Exhibition Centre, Brisbane, Queensland (Australia), 28 Jun-1 Jul 2006, IADR , 2006Conference paper (Other academic)
    Abstract [en]

    Objectives: To investigate how E-modulus, degree of conversion (DC%) and rate of polymerization of the most used monomer resins in dental light-cure composites interact. Methods: Young's modulus and DC% were studied for 21 different resin combinations of three commonly used dental monomers, bis-GMA, TEGDMA and UEDMA (combinations of 0, 20, 40, 60 and 100 wt% as it is illustrated in the figure). For each resin combination 6 specimens were tested. Small Instron and differential scanning calorimetry (photo-calorimetry) were used as testing machines. The results were tested using ANOVA and Duncan's multiple range tests and regular t-test. Results: Rate of polymerization was significantly (p<0.05) higher when the wt% of the TEGDMA was high in the mixtures compare to highly concentrated bis-GMA. DC% was significantly high (p<0.05) for binary mixture of UEDMA and TEGDMA. The DC% was significantly lower for 100 wt% bis-GMA (p<0.05). The calculated values for DC% were between 53.1%± 0.9% and 85.6%±1%. Young's modulus values varied between 2.37± 0.15 GPa and 4.15± 0.2 GPa. It was noticeable that by adding TEGDMA to bisGMA or UEDMA, the Young's modulus decreased significantly (p<0.05). There were no significant (p>0.05) differences between Young's modulus values when the monomer mixtures contained bis-GMA, TEGDMA and UEDMA at different concentration levels. The higher the concentration of bisGMA in the monomer mixture, the lower was the degree of conversion. However, Young's modulus increased at higher concentration of bis-GMA. Conclusions: The differences in the values for degree of conversion were mostly justified by the differences in the molecular structures of the different monomers. It was also revealed that higher degree of conversion does not always result in a higher Young's modulus, because molecular and network structural parameters play major roles in the final mechanical/physical properties of the mixtures.

  • 28.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan M.
    Department of Dental Biomaterials, University of Florida.
    Influence of light-curing procedures and photo-initiator/co-initiator composition on the degree of conversion of light-curing resins2005In: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 16, no 1, p. 47-52Article in journal (Refereed)
    Abstract [en]

    Objective: The hypothesis that the degree and rate of conversion can be modified favourably by using different light-curing procedures and different photo initiator/co-initiator combinations was tested.Method: A photo-initiator (0.02 mM/g resin); either camphorquinone (CQ) or 1-phenyl-1,2-propanedione (PPD), was mixed with bisGMA:TEGDMA (50:50 by weight). In addition, a co-initiator (0.04 mM/g resin); either N,N-dimethyl-p-aminobenzoic acid ethylester (DABE), N,N-cyanoethylmethylaniline (CEMA), or 2-dimethylaminoethyl methacrylate (DMAEMA), was added. These six combinations were subjected to three curing conditions (standard curing, soft-start curing or LED curing). The conversion levels (DC) were determined with differential scanning calorimetry (DSC). The DSC results were analysed using a general linear model (GLM) and Duncans multiple range test and regular t-test.Results: The fastest conversion initially was obtained by standard curing, followed by LED curing and soft-start curing. After 40 s of curing, conventional curing and soft-start curing produced a higher DC than LED curing. However, strong interactions occurred between the different variables (curing method, initiator and co-initiator). Initially, CQ was more efficient than PPD, but after 40 s, this difference was insignificant.Conclusion: By using soft-start curing and an appropriate photo initiator/co-initiator combination it is possible to achieve slow curing and a high DC at within a curing time of 40 s.

  • 29.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan M.
    Berglund, Lars A.
    Luleå tekniska universitet.
    Effect of light power density variations on bulk curing properties of dental composites2003In: Journal of Dentistry, ISSN 0300-5712, E-ISSN 1879-176X, Vol. 31, no 3, p. 189-196Article in journal (Refereed)
    Abstract [en]

    Objective. The hypothesis that low light intensity and long but sufficient curing time can produce composites with volumetric shrinkage, degree of conversion (DC%) and Young's modulus (E-modulus) comparable to those of high light intensity cured composite was tested, when the contraction strain and heat generation were lower with low light intensity curing. Methods. Dental composites (Z100 and Z250, 3M ESPE) were investigated. Specimens were cured with light intensities of 200, 450 and 800 mW/cm2 for 140, 60 and 35 s from a distance of 7 mm. Strain-gages were used for contraction strain measurements. DC% was measured at the top and the bottom of 4 mm thick samples using FT-Raman spectroscopy. Volumetric polymerization shrinkage was determined using a water displacement method. E-modulus was determined in tension on composite specimens. Results. The results were analyzed using ANOVA and Duncan's multiple range tests and regular t-test. Polymerization stress level decreased significantly (p<0.05) when cured with 200 mW/cm2 rather than with 800 mW/cm2. Temperature rises were significantly different (p<0.05) for different composites and light intensity values. Reduction in light intensity did not decrease the DC% values significantly at the top surfaces. The most dramatic differences existed between top and bottom surfaces (p<0.05) rather than among curing groups. Measured E-modulus and volumetric shrinkage values were not significantly different (p>0.05) between different light intensity groups. Conclusion. DC%, E-modulus and the volumetric shrinkage values in cured composites were not affected by low light intensity, however, the contraction strain and polymerization's exotherm were decreased. Thus our results support the proposed hypothesis.

  • 30.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Tavassoli, Sara
    Department of Carilogy and Preventive Dentistry, Tehran.
    Mehran, Majid
    Department of Carilogy and Preventive Dentistry, Tehran.
    Shear bond strength of sealant to primary and permanent enamel2010Conference paper (Refereed)
    Abstract [en]

    Objectives: The purpose of this study was to compare the effect of phosphoric acid, one-bottle adhesive and self-etching adhesive on shear bond strength (SBS) of light-curing sealant to ungrounded primary and permanent enamel.Methods: In this in vitro study 30 primary molars and 30 permanent premolars were cleaned and divided to 6 groups (n=10). The following materials used on flattest, peripheral surface (mesial or distal) of permanent (groups 1,3,5) and primary (groups 2,4,6) teeth. Group 1&2 (control): acid etching + light-Curing sealant (Concise 3M-ESPE). Group 3&4 (SB): acid etching +2 layer bonding agent (Single Bond 3M-ESPE) + sealant. Group 5&6 (PLP): self etching adhesive (Prompt L-Pop 3M-ESPE) +sealant. The teeth were thermocycled 500 cycles between 5„a and 55„a with a dwell time of 30s. For shear bond strength testing, the load was applied vertically from the Zwick universal testing machine with load cell 10KN to the base of the mold at a cross-head speed of 5 mm/min. Then two way variance analysis (Between-Subject Effect) and multiple comparisons (Post Hoc Test-LSD) were performed. Failure mode was determined in a stereomicroscope at x20. Result: There was no significant difference in SBS between control (1&2), and PLP (5&6) groups, neither between SB (3&4) and PLP (5&6) groups (P>0.5). But there was significant difference in SBS between control and SB (3&4) groups (P=0.22). However, the SBS to primary enamel were lower than those to permanent enamel (P<0.5). Conclusion: The self-etching adhesive Prompt L-Pop, is as effective as conventional acid-etching in mediating a bond between a light-curing sealant and ungrounded human enamel. Applying Single Bond adhesive under fissure sealant would be beneficial for increasing the bond strength.

  • 31.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Tavassolie, Sara
    Dental Faculty, Shahed University.
    Mehran, M
    Dental Faculty, Shahed University.
    Sealant microleakage study of two-component self-etch and one-component total-etch adhesives2009Conference paper (Other academic)
  • 32. Enqvist, Evelina
    et al.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Nanodiamond reinforced ultra high molecular weight polyethylene for orthopaedic applications: Dry versus wet ball milling manufacturing method2014In: Tribology - Materials, Surfaces & Interfaces, ISSN 1751-5831, E-ISSN 1751-584X, Vol. 8, no 1, p. 42564-Article in journal (Refereed)
    Abstract [en]

    Nanodiamonds (NDs) were investigated as reinforcement for ultra high molecularweight polyethylene (UHMWPE). Dry and wet mixing with planetary ball milling was compared and analysed by scanning electron microscopy (SEM), differential scanning calorimerty (DSC), X-ray diffraction (XRD) and contact angle measurements. The composites were mixed from one to four hours to study the dispersion of the nanoparticles. It was concluded that wet mixing is more effective at distributing nanodiamonds in comparison to dry mixing. It could also be concluded that dry mixing increases the temperature by 20°C more than wet mixing which resulted in a more distinct welding process of the UHMWPE powder.

  • 33. Enqvist, Evelina
    et al.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Grácio, José
    TEMA-NRD, Mechanical Engineering Department, University of Aveiro.
    Gonçalves, Gil
    TEMA-NRD, Mechanical Engineering Department, University of Aveiro.
    Marques, Paula
    TEMA-NRD, Mechanical Engineering Department, University of Aveiro.
    Optimisation of manufacturing process of UHMWPE/nanoHA/MWCNTs2010Conference paper (Other academic)
    Abstract [en]

    Hip- and knee replacements are amongst the most common performed surgical operations performed today. Ultra high molecular weight polyethylene (UHMWPE) is frequently used for joint-replacements due to its excellent properties such as high impact strength, toughness and low friction. Wear debris produced when UHMWPE is sliding against a metal counter face is one of the major causes of total failure of implant as an effect of wear debris induced osteolysis. The nano scale dimensions of Carbon nanotubes (CNTs) give them unique physical and chemical properties. Their high aspect ratio makes them perfect as reinforcement in composite materials. Hydroxyapatite (HA) is similar in chemical composition and structure to apatite naturally occurring in human bone tissue and is thus positively affecting bone integration. However the brittleness and poor strength of HA limits the use of HA in load-bearing areas. This work focuses on the manufacturing of a new CNT and HA reinforced UHMWPE bio nanocomposite, using solvent casting and a melt-mixing method. Hot press was used to fabricate the final sample. The produced bio-nanocomposite was characterized by use of differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and micro-Raman spectroscopy. Nanoindentation was used to study the hardness and elastic modulus of samples containing CNTs and different HA loading.

  • 34.
    Enqvist, Evelina
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Marques, Paula
    TEMA – NRD, Mechanical Engineering Department, University of Aveiro, 3810-193 Aveiro, Portugal. Aveiro Institute of Nanotechnology (AIN).
    Grásio, José
    TEMA – NRD, Mechanical Engineering Department, University of Aveiro, 3810-193 Aveiro, Portugal. Aveiro Institute of Nanotechnology (AIN).
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Nanoparticle reinforced UHMWPE for orthopaedic applications: Parameters affecting the manufacturing process2012Conference paper (Refereed)
  • 35.
    Enqvist, Evelina
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Ramanenka, Dmitrij
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Grácio, José
    TEMA – NRD, Mechanical Engineering Department, University of Aveiro, 3810-193 Aveiro, Portugal. Aveiro Institute of Nanotechnology (AIN).
    Marques, Paula
    TEMA – NRD, Mechanical Engineering Department, University of Aveiro, 3810-193 Aveiro, Portugal. Aveiro Institute of Nanotechnology (AIN).
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    The effect of ball milling time and rotational speed on ultra high molecular weight polyethylene reinforced with multiwalled carbon nanotubes2016In: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569, Vol. 37, no 4, p. 1128-1136Article in journal (Refereed)
    Abstract [en]

    Ultra high molecular weight polyethylene (UHMWPE) composites reinforced with multiwalled carbon nanotubes (MWCNT) were produced using planetary ball milling. The aim was to develop a more wear resistant composite with increased mechanical properties to be used in stress bearing joints. The manufacturing technique, using ball-milling to incorporate MWCNT into UHMWPE matrix was investigated. The effect of manufacturing parameters such as effect of ball milling time and rotational speed on final composite was analyzed by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), particle size distribution and contact angle measurements. Ball milling as mixing technique for UHMWPE based composites is not a new approach but yet, the effect of time, rotational speed, loading of milling jar and type of ball mill has not been reported properly for UHMWPE. 0.5 and 1 wt% UHMWPE/MWCNTs were manufactured at different rotational speed and mixing time. The results indicate that rotational speed rather than mixing time is important for dispersing MWCNTs

  • 36.
    Golchin, Arash
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Villain, Alexis
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Tribological Behaviour of Nanodiamond Reinforced UHMWPE in Water-Lubricated Contacts2017In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 110, p. 195-200Article in journal (Refereed)
    Abstract [en]

    In this study, the tribological behaviour of nanodiamond reinforced UHMWPE composites was investigated in water-lubricated sliding contacts. A significant reduction of 72% in wear and 24% in friction of UHMWPE was observed with incorporation of 1 wt% nanodiamond in the polymer matrix. Various bulk and surface characterization techniques were utilised to reveal the main mechanisms involved in the friction and wear response of the polymeric materials. The improved tribological behaviour of UHMWPE upon incorporation of various loadings of nanodiamond in the polymer matrix was mainly attributed to the boundary lubricating action of nanodiamonds and the polishing effect of the nanodiamond reinforced UHMWPE composites on the counter surfaces in water-lubricated sliding contacts.

  • 37.
    Golchin, Arash
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Wikner, Alfred
    Luleå University of Technology.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    An Investigation into Tribological Behaviour of Multi-Walled Carbon Nanotube/Graphene Oxide Reinforced UHMWPE in Water Lubricated Contacts2016In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 95, p. 156-161Article in journal (Refereed)
    Abstract [en]

    In this study, the influence of incorporation of carbon based nano fillers, namely multi-walled carbon nanotubes and graphene oxide on the tribological behaviour of ultra-high molecular weight polyethylene was investigated in water lubricated sliding contacts. Further investigations were carried out to study the influence of γ-irradiation and hygrothermal aging on the friction and wear response of the polymeric materials. It was found that regardless of the treatment, GO/MWNT reinforced composites consistently exhibited a lower friction and higher wear resistance in comparison to the unfilled UHMWPE. This was mainly attributed to the lubricating action of the carbonaceous nano fillers in water lubricated sliding contacts.

  • 38.
    Goncalves, Gil
    et al.
    TEMA-NRD, Mechanical Engineering Department, University of Aveiro.
    Marques, Paula
    TEMA-NRD, Mechanical Engineering Department, University of Aveiro.
    Barros-Timmons, Ana
    CICECO, Department of Chemistry, University of Aveiro.
    Bdkin, Igor
    TEMA-NRD, Mechanical Engineering Department, University of Aveiro.
    Singh, Manoj
    TEMA-NRD, Mechanical Engineering Department, University of Aveiro.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Gracio, Jose
    TEMA-NRD, Mechanical Engineering Department, University of Aveiro.
    Graphene oxide modified with PMMA via ATRP as a reinforcement filler2010In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 40, no 44, p. 9927-9934Article in journal (Refereed)
    Abstract [en]

    Graphene is a two-dimensional new allotrope of carbon, which is stimulating great curiosity due to its superior mechanical, electrical, thermal and optical properties. Particularly attractive is the availability of bulk quantities of graphene (G) which can be easily processed by chemical exfoliation, yielding graphene oxide (GO). The resultant oxygenated graphene sheets covered with hydroxyl, epoxy and carboxyl groups offer tremendous opportunities for further functionalization opening plenty of opportunities for the preparation of advanced composite materials. In this work poly(methyl methacrylate) (PMMA) chains have been grafted from the GO surface via atom transfer radical polymerization (ATRP), yielding a nanocomposite which was soluble in chloroform. The surface of the PMMA grafted GO (GPMMA) was characterized by AFM, HRTEM, Raman, FTIR and contact angle. The interest of these novel nanocomposites lies in their potential to be homogenously dispersed in polymeric dense matrices and to promote good interfacial adhesion, of particular relevance in stress transfer to the fillers. PMMA composite films were prepared using different percentages of GPMMA and pristine GO. Mechanical analysis of the resulting films showed that loadings as low as 1% (w/w) of GPMMA are effective reinforcing agents, yielding tougher films than pure PMMA films and even than composite films of PMMA prepared with GO. In fact, addition of 1% (w/w) of GPMMA fillers led to a significant improvement of the elongation at break, yielding a much more ductile and therefore tougher material. Thermal analysis showed an increase of the thermal stability properties of these films providing evidence that strong interfacial interactions between PMMA and GPMMA are achieved. In addition, AFM analysis, in friction force mode, is demonstrated to be an effective tool to analyse the surface filler distribution on polymer matrices

  • 39.
    Gonçalves, Gil
    et al.
    TEMA-NRD, Mechanical Engineering Department, University of Aveiro, University of Aveiro, Nanotechnology Research Division, University of Aveiro.
    Vila, Mercedes
    TEMA-NRD, Mechanical Engineering Department, University of Aveiro.
    Bdikin, Igor
    TEMA-NRD, Mechanical Engineering Department, University of Aveiro.
    Andres, Alicia de
    Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Ferreira, Rute A.S.
    Physics Department and CICECO, University of Aveiro.
    Carlos, Luis D.
    Physics Department and CICECO, University of Aveiro.
    Gracio, Jose
    TEMA-NRD, Mechanical Engineering Department, University of Aveiro.
    Marques, Paula A.P.A.
    TEMA-NRD, Mechanical Engineering Department, University of Aveiro.
    Breakdown into nanoscale of graphene oxide: Confined hot spot atomic reduction and fragmentation2014In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 4, article id 6735Article in journal (Refereed)
    Abstract [en]

    Nano-graphene oxide (nano-GO) is a new class of carbon based materials being proposed for biomedical applications due to its small size, intrinsic optical properties, large specific surface area, and easy to functionalize. To fully exploit nano-GO properties, a reproducible method for its production is of utmost importance. Herein we report, the study of the sequential fracture of GO sheets onto nano-GO with controllable lateral width, by a simple, and reproducible method based on a mechanism that we describe as a confined hot spot atomic fragmentation/reduction of GO promoted by ultrasonication. The chemical and structural changes on GO structure during the breakage were monitored by XPS, FTIR, Raman and HRTEM. We found that GO sheets starts breaking from the defects region and in a second phase through the disruption of carbon bonds while still maintaining crystalline carbon domains. The breaking of GO is accompanied by its own reduction, essentially by the elimination of carboxylic and carbonyl functional groups. Photoluminescence and photothermal studies using this nano-GO are also presented highlighting the potential of this nanomaterial as a unique imaging/therapy platform

  • 40.
    Henriques, Bruno
    et al.
    CESAM & Department of Chemistry, University of Aveiro.
    Gonçalves, Gil
    TEMA-NRD, Mechanical Engineering Department, University of Aveiro, University of Aveiro, Nanotechnology Research Division, University of Aveiro.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Pereira, Eduarda
    CESAM & Department of Chemistry, University of Aveiro.
    Vila, Mercedes
    TEMA-NRD, Mechanical Engineering Department, University of Aveiro.
    Marques, Paula A.P.A.
    TEMA-NRD, Mechanical Engineering Department, University of Aveiro.
    Optimized graphene oxide foam with enhanced performance and high selectivity for mercury removal from water2016In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 301, p. 453-461Article in journal (Refereed)
    Abstract [en]

    This work explores the preparation of three-dimensional graphene oxide macroscopic structures, shaped by self-assembling single graphene oxide (3DGO) sheets with control of its surface chemistry by combining with nitrogen functional groups (3DGON), or with nitrogen and sulphur functional groups (3DGOSN), and their application in the removal of mercury (Hg(II)) from aqueous solutions. The chemical structure of the materials was assessed by using different characterization techniques: SEM, XPS and BET. Adsorption studies conducted in Hg(II) contaminated ultra-pure water reveal the enhanced ability of 3DGON for the adsorption of this metal, when compared to the other GO foams. A small dose of 3DGON (10 mg L−1) allows to remove up to 96% of Hg(II) after 24 h of contact time, leading to a residual concentration in solution close to the guideline value for drinking water (1 μg L−1). The ability of this material to adsorb Hg (II) was evaluated relatively to different experimental parameters such as pH, sorbent dose, time and effect on different competing metal ions. Real application was also evaluated by testing its performance in two different natural matrices, river and sea water, with very promising results.

  • 41.
    Hu, Xinming
    et al.
    School of Mechanical Engineering, University of Leeds.
    Sin, Jorge Rituerto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Neville, Anne
    School of Mechanical Engineering.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Tribocorrosion behaviour of Hf in Simulated Body Fluids2012Conference paper (Refereed)
  • 42.
    Li, Bin
    et al.
    Department of Mechanical Engineering, Wichita State University.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Gong, Guan
    Swerea SICOMP AB, Box 271, 941 26, Piteå.
    Song, Weidong
    Department of Mechanical Engineering, Wichita State University, PD Materials, Boeing Commercial Airplanes, Seattle, WA 98124.
    Applications of Nanomaterials in Multifunctional Polymer Nanocomposites2016In: Journal of Nanomaterials, ISSN 1687-4110, E-ISSN 1687-4129, Vol. 2016, article id 5790194Article in journal (Other academic)
  • 43.
    Lindberg, A.
    et al.
    Public Dental Health Clinic, Skellefteå.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Dijken, JW. van
    Department of Odontology, Dental School Umeå.
    A Fourier transform Raman spectroscopy analysis of the degree of conversion of a universal hybrid resin composite cured with light-emitting diode curing units2005In: Swedish Dental Journal, ISSN 0347-9994, Vol. 29, no 3, p. 105-112Article in journal (Refereed)
    Abstract [en]

    The degree of conversion (DC), of a universal hybrid resin composite cured with LED curing units with low and high power densities and a 510 mW/cm2 quartz tungsten halogen unit, was investigated with Fourier Transform Raman spectroscopy. Three curing depths (0, 2, 4mm) and 0 and 7 mm light guide tip - resin composite (LT - RC) distances were tested. The DC of the LED units varied between 52.3% - 59.8% at the top surface and 46.4% - 57.0% at 4 mm depth. The DC of specimen cured with a 0 mm LT- RC distance at 4 mm depth varied between 50.8% - 57.0% and with 7 mm distance between 46.4% - 55.4%. The low power density LED unit showed a significantly lower DC for both distances at all depth levels compared to the other curing units (p < 0.05). Significant differences between the other curing units were only found at the 4 mm depth level cured from 7 mm distance (p < 0.05). The reduction in DC by increasing LT- RC distance was less than 10% for all curing units. It can be concluded that the improved LED curing units could cure the studied resin composite to the same DC as the control unit.

  • 44.
    Lindberg, Anders
    et al.
    Umeå universitet.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Djiken, Jan van
    Umeå universitet.
    Comparison of the effect of different LED curing units on depth of cure2005In: Swedish Dental Journal, ISSN 0347-9994, Vol. 29, no 3, p. 105-112Article in journal (Refereed)
  • 45.
    Melk, Latifa
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Mechanical and thermal performances of UHMWPE blended vitamin E reinforced carbon nanoparticle composites2018In: Composites Part B: Engineering, ISSN 1359-8368, E-ISSN 1879-1069, Vol. 146, p. 20-27Article in journal (Refereed)
    Abstract [en]

    Ultrahigh molecular weight polyethylene (UHMWPE) is a known to be the material of choice for bearing components in joint arthroplasty. However, oxidation wear of UHMWPE components is considered to be a major drawback limiting the lifespan of implants. Vitamin E was considered as a promising antioxidant to prevent long-term oxidation and reduce the wear degradation of UHMWPE material. Nevertheless, there are limited results on the improvements of vitamin E on the mechanical and thermal properties of UHMWPE. In this study, we investigated the incorporation of 0.5–3 wt.% carbon nanoparticles: Multiwalled Carbon Nanotubes (MWCNTs), Graphene (GO) and Nanodiamonds (ND) on the mechanical and thermal properties of UHMWPE blended vitamin E (UHMWPE-E). Surface analysis of the composite powders showed well-dispersed carbon nanoparticles within the UHMWPE-E matrix. Thermogravimetric (TGA) and Differential Scanning Calorimetry (DSC) were used to study the thermal behavior of the nanocomposites. It was found that the addition of GO, MWCNTs and ND improved the thermal stability of the nanocomposites compared to neat UHMWPE-E. However, the addition of carbon nanoparticles had no significant effect on the crystallization parameters of the composites. In addition, the incorporation of MWCNT and ND improved significantly the fracture toughness of the composites. The addition of 0.7 wt.% ND and 1 wt.% MWCNT increased the fracture toughness from 5.93 MPa m1/2 for neat UHMWPE-E to 7.38 and 9.19 MPa m1/2 respectively. The enhanced fracture toughness and thermal stability of the nanocomposites could be due to the successful powder processing technique where an optimized mixing and ball milling parameters were used.

  • 46.
    Moreno, Silvia Suñer
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Bladen, Catherine L.
    Institute of Medical and Biological Engineering, University of Leeds.
    Gowland, Nicholas
    Institute of Medical and Biological Engineering, University of Leeds.
    Tipper, Joanne L.
    Institute of Medical and Biological Engineering, University of Leeds.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Investigation of wear and wear Particles from a UHMWPE/multi-walled carbon nanotube nanocomposite for total joint replacements2014In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 317, no 1-2, p. 163-169Article in journal (Refereed)
    Abstract [en]

    Ultra high molecular weight polyethylene (UHMWPE) has been extensively used as a bearing surface in joint prostheses. However, wear debris generated from this material has been associated with osteolysis and implant loosening. Alternative materials, such as polymer composites, have been investigated due to their exceptional mechanical properties. The goal of the present work was to investigate the wear rate, size and volume distributions, bioactivity and biocompatibility of the wear debris generated from a UHMWPE/Multi-walled carbon nanotube (MWCNT) nanocomposite material compared with conventional UHMWPE. The results showed that the addition of MWCNTs led to a significant reduction in wear rate. Specific biological activity and functional biological activity predictions showed that wear particles from the UHMWPE/MWCNT nanocomposite had a reduced osteolytic potential compared to those produced from the conventional polyethylene. In addition, clinically relevant UHMWPE/MWCNT wear particles did not show any adverse effects on the L929 fibroblast cell viability at any of the concentrations tested over time. These findings suggest that UHMWPE/MWCNT nanocomposites represent an attractive alternative for orthopaedic applications.

  • 47.
    Moreno, Silvia Suñer
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Investigation of graphene oxide as reinforcement for orthopaedic applications2014In: Tribology - Materials, Surfaces & Interfaces, ISSN 1751-5831, E-ISSN 1751-584X, Vol. 8, no 1, p. 1-6Article in journal (Refereed)
    Abstract [en]

    Carbon based polymer composites have been suggested as an alternative to conventional ultra high molecular weight polyethylene (UHMWPE) in total joint replacements. The aim of this study was to investigate the use of graphene oxide (GO) as reinforcement of UHMWPE. Under optimised mixing conditions, the prepared UHMWPE/GO composite showed an enhanced thermal stability compared to conventional UHMWPE. Also, the present study has shown the potential of ball milling as a processing method for synthesising UHMWPE/GO composites to be used in load bearing implants.

  • 48.
    Moreno, Silvia Suñer
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Joffe, Roberts
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Tipper, Joanne
    Institute of Medical and Biological Engineering, University of Leeds.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    UHMWPE/GO nanocomposites for orthopaedic applications: thermal, mechanical and tribological characterization2014Conference paper (Refereed)
    Abstract [en]

    Metal-on-Polyethylene (MoP) is the bearing combination most commonly used in total joint replacements. However, the degradative oxidation behaviour of ultra high molecular weight polyethylene (UHMWPE) leads to high amounts of wear debris, which contributes to the development of aseptic loosening and eventually to the failure of the implant. In order to address this issue, investigations have focused on the development of novel materials with improved characteristics. Recently, Graphene oxide (GO) has generated great interest as reinforcement for polymer matrices due to its excellent mechanical properties. The aim of this study was to investigate the possibilities of UHMWPE/GO nanocomposites for their use in joint implants.UHMWPE/GO nanocomposites with different wt% GO content, up to 2 wt%, were manufactured under optimised conditions using a ball milling technique. Thermal, mechanical and structural characterizations of the UHMWPE/GO nanocomposites and conventional UHMWPE were carried out by means of Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), uniaxial tensile tests and High Resolution Scanning Electron Microscopy (HR-SEM). Contact angle measurements were carried out to investigate the wettability of the materials. In addition, the tribological performance of the novel nanocomposites will be assessed with a six-station multidirectional pin on plate wear simulator under hip kinematics.The results showed that GO has the ability to improve the performance of conventional UHMWPE. The incorporation of GO enhanced the thermal stability and oxidative resistance of conventional UHMWPE. Under optimised conditions, the mechanical properties and wettability of the nanocomposites were also improved. These findings suggest that UHMWPE/GO nanocomposites might be an interesting alternative to conventional UHMWPE for their use in orthopaedic aplications and more research concerning the biocompatibility and tribological performance of this material is currently under investigation.

  • 49.
    Moreno, Silvia Suñer
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Joffe, Roberts
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Tipper, Joanne
    Institute of Medical and Biological Engineering, University of Leeds.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Ultra High Molecular Weight Polyethylene/Graphene Oxide Nanocomposites: Thermal, Mechanical and Wettability Characterisation2015In: Composites Part B: Engineering, ISSN 1359-8368, E-ISSN 1879-1069, Vol. 78, p. 185-191Article in journal (Refereed)
    Abstract [en]

    Numerous carbon nanostructures have been investigated in the last years due to their excellent mechanical properties. In this work, the effect of the addition of graphene oxide (GO) nanoparticles to UHMWPE and the optimal %wt GO addition were investigated. UHMWPE/GO nanocomposites with different GO wt% contents were prepared and their mechanical, thermal, structural and wettability properties were investigated and compared with virgin UHMWPE. The results showed that the thermal stability, oxidative resistance, mechanical properties and wettability properties of UHMWPE were enhanced due to the addition of GO. UHMWPE/GO materials prepared with up to 0.5 wt% GO exhibited improved characteristics compared to virgin UHMWPE and nanocomposites prepared with higher GO contents.

  • 50.
    Moreno, Silvia Suñer
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Tipper, Joanne
    Institute of Medical and Biological Engineering, University of Leeds.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Biological effects of wear particles generated in total joint replacements: trends and future prospects2011Conference paper (Refereed)
    Abstract [en]

    Joint replacements have considerably improved the quality of life of patients with joints damaged by disease or trauma. However, problems associated with wear particles generated due to the relative motion between the components of the bearing are still present and can lead to the eventual failure of the implant. The biological response to wear debris is directly related to prosthesis longevity. The identification of the mechanisms by which cells respond to wear debris and how particles distribute around the human body may provide valuable information for the long term success of artificial joints.During the last few decades, orthopaedic research has been focused on predicting the in vivo performance of joint replacements. However, the exact interrelationship between material physicochemical properties and inflammatory response is not fully understood to date. Laboratory wear simulators provide an accurate prediction of implant wear performance. However, particles generated from such wear simulators require validation to compare them with particles extracted from peri-implant tissues. The present work focuses initially on the advantages and disadvantages of the different bearing combinations (hard-on-soft and hard-on-hard bearings). In addition, the similarities between particles observed in vivo and those generated in vitro to predict the cellular response to wear debris is discussed. Finally, the biological effects of the degradation products generated by wear and corrosion are described.

12 1 - 50 of 73
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf