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Histology and micro-CT study of diamond-coated metal bone implants in rabbit femurs
Potocký, Štěpán; Ižák, Tibor; Dragounová, Kateřina; Kromka, Alexander; Rezek, Bohuslav; Mandys, V.; Bartoš, M.; Bačáková, Lucie; Sedmera, David
2018 - English
A conformal coating of a thin diamond layer on three-dimensional metal bone implants was shown directly on stainless steel and TiAl6V4 cortical screw implant using ultrasonic and composite polymer pretreatment method. The best conformation coverage was achieved in the case of the WO3 interlayer for both stainless steel and TiAl6V4 screws. The process of osteointegration of the screw implants into rabbit femurs is evidenced by the formation of a bone edge via desmogenous ossification around the screws in less than six months after implantation. A detailed evaluation of the tissue reaction around the implanted screws shows good biocompatibility of diamond-coated metal bone implants.
Keywords:
screw implant; diamond coating; osteointegration; histology
Available at various institutes of the ASCR
Histology and micro-CT study of diamond-coated metal bone implants in rabbit femurs
A conformal coating of a thin diamond layer on three-dimensional metal bone implants was shown directly on stainless steel and TiAl6V4 cortical screw implant using ultrasonic and composite polymer ...
Electronic transfer between nanostructures. Negative differential resistance in conductive polymers.
Král, Karel; Menšík, Miroslav
2018 - English
The effect of negative differential resistance can be observed experimentally in some material systems based on polymers. These observation are explained usually to be due to the presence of certain carrier traps which can capture the carriers of the electric current. In the present theoretical work we are going to show that besides this carrier trapping origin of the negative differential resistance there can also be an intrinsic mechanism present, causing such an effect. Namely, instead of the traps, the electron-phonon interaction can cooperate with the tunneling of the charge carriers between their localized states and can provide the effect the negative differential resistance. This electron-phonon interaction is included in a non-perturbative way. The theory will be briefly summarized and explained.
Keywords:
electronic transfer; charge transfer; nanostructures; quantum dots; nonequilibrium transport theory
Available at various institutes of the ASCR
Electronic transfer between nanostructures. Negative differential resistance in conductive polymers.
The effect of negative differential resistance can be observed experimentally in some material systems based on polymers. These observation are explained usually to be due to the presence of certain ...
Mechanical properties of Cr-DLC layers prepared by hybrid laser technology
Písařík, Petr; Jelínek, Miroslav; Remsa, J.; Tolde, Z.
2017 - English
Diamond like carbon (DLC) layers have excellent biological properties for use in medicine for coating implants, but poor adhesion to biomedical alloys (titanium alloys, chromium alloys and stainless steel). The adhesion can be improved by doping the DLC layer by chromium, as described in this article. Chromium doped diamond like carbon layers (Cr DLC) were deposited by hybrid deposition system using KrF excimer laser (deposition diamond like carbon - graphite target) and\nmagnetron sputtering (deposition chromium - chromium target). Carbon and chromium contents were determined by wavelength dispersive X-ray spectroscopy.\n
Keywords:
DLC; chromium doped; mechanical properties; PLD
Available at various institutes of the ASCR
Mechanical properties of Cr-DLC layers prepared by hybrid laser technology
Diamond like carbon (DLC) layers have excellent biological properties for use in medicine for coating implants, but poor adhesion to biomedical alloys (titanium alloys, chromium alloys and stainless ...
Correlated microscopy of electronic and material properties of graphene grown on diamond thin films
Rezek, Bohuslav; Čermák, Jan; Varga, Marián; Tulic, S.; Skákalová, V.; Waitz, T.; Kromka, Alexander
2017 - English
In this work we compare growth of graphene on diamond thin films that enable large area processing. We use films with different crystal size and surface roughness to obtain deeper insight into formation and properties of GoD. The diamond films are coated by a nm thin sputtered Ni layer and heated to 900°C in a forming gas atmosphere (H2/Ar) to initiate catalytic thermal CVD process. The samples are cleaned from residual Ni after the growth process. We employ scanning electron microscopy, Raman micro-spectroscopy and Kelvin probe force microscopy to correlate material, structural, and electronic properties of graphene on diamond. We show how grain size and grain boundaries influence graphene growth and material and electronic properties. For instance we show that the grain boundaries (with non-diamond carbon phases) in diamond films have an important role. They influence the electronic properties and they are beneficial for forming graphene on diamond higher quality.
Keywords:
graphene; diamond; microscopy; micro-spectroscopy; electronic properties
Available at various institutes of the ASCR
Correlated microscopy of electronic and material properties of graphene grown on diamond thin films
In this work we compare growth of graphene on diamond thin films that enable large area processing. We use films with different crystal size and surface roughness to obtain deeper insight into ...
Performance of cement composites reinforced with surface-modified polypropylene micro-fibers
Antoš, J.; Dejdar, L.; Trejbal, J.; Prošek, Zdeněk
2017 - English
This paper focuses on the mechanical properties investigation of cement pastes reinforced with surface treated polymer fibers. The cement matrix was composed of Portland cement (CEM I 42.5 R, w/c ratio equal to 0.4). Two polypropylene fiber types (micro-and macro-fibers) were used as randomly distributed and oriented reinforcement in volume amount of 2 %. The fibers were modified in the low-pressure inductively coupled cold oxygen plasma in order to enhance their surface interaction with the cement matrix. The investigated composite mechanical properties (load bearing capacity and response during loading) were examined indirectly by means of four-point bending mechanical destructive tests. A response of loaded samples containing treated fibers were compared to samples with reference fibers. Moreover, cracking behavior development was monitored using digital image correlation (DIC). This method enabled to record the micro-cracks system evaluation of both fiber reinforced samples.\n
Keywords:
cement composite; fiber reinforcement; polymeric fiber; surface modification; four-point bending; plasma treatment
Available at various institutes of the ASCR
Performance of cement composites reinforced with surface-modified polypropylene micro-fibers
This paper focuses on the mechanical properties investigation of cement pastes reinforced with surface treated polymer fibers. The cement matrix was composed of Portland cement (CEM I 42.5 R, w/c ...
Structure and properties of DLC layers for industrial applications
Mates, Tomáš; Ledinský, Martin; Vetushka, Aliaksi; Pikna, Peter; Fejfar, Antonín; Marek, A.; Vyskočil, J.; Erichsen, J.; Dawah, P.
2017 - English
Diamond-like carbon (DLC) layers based on amorphous carbon are used for wide range of applications, mostly for mechanical protection of various industrial components. We examined DLC layers at micro- and nanoscale by two independent microscopic techniques: Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) with a good agreement. We compared DLC layers grown on steel substrate and Si wafer and found similarly structured clusters and a certain difference in the density of nucleation centres. The measurements of local mechanical properties by the AFM tip revealed that the Si wafer behaves as softer material compared to the growing DLC nanoclusters that also exhibit lower values in the map of the relative local friction coefficient. Finally, we observed changes in the Raman spectra of the DLC exposed to annealing at ambient conditions and found a gradual shift from the diamond phase to the graphite phase as a function of increasing temperature.
Keywords:
DLC; PACVD; AFM; SEM; Raman
Available at various institutes of the ASCR
Structure and properties of DLC layers for industrial applications
Diamond-like carbon (DLC) layers based on amorphous carbon are used for wide range of applications, mostly for mechanical protection of various industrial components. We examined DLC layers at micro- ...
Characterization and tribological testing of a carbon-based nanolayer prepared by ion beam assisted deposition
Horažďovský, T.; Kovač, J.; Drbohlav, Ivo
2017 - English
Carbon-based nanolayers have been attracting much attention due to their excellent low-friction properties, their high hardness and their good wear resistance. In this work we present the results of material research aimed at reducing the friction of the functional surfaces of titanium implants, and thus extending their lifetime to reoperation. An analysis of the chemical composition showed that the modified surface is composed of a carbon-based nanolayer, a mixed interface, and a nitrogen-enriched sublayer. Raman spectroscopy showed the DLC character of the carbon-based nanolayer with sp2 rich bonds. A TiN compound was detected by X-ray diffraction in the modified surface area.\n
Keywords:
nanolayer; friction; nanohardness
Available at various institutes of the ASCR
Characterization and tribological testing of a carbon-based nanolayer prepared by ion beam assisted deposition
Carbon-based nanolayers have been attracting much attention due to their excellent low-friction properties, their high hardness and their good wear resistance. In this work we present the results of ...
Miniaturized boron doped diamond film electrode for neuroblastoma biomarkers determination
Hrdlička, Vojtěch; Barek, J.; Navrátil, Tomáš; Taylor, Andrew
2017 - English
Cathodically pretreated miniaturized boron doped diamond film electrodewas successfully tested for the purposes of in-situ determination of neuroblastoma biomarkers after hollow-fibre based microextraction. Electrode was tested using K-3[Fe(CN)(6)] and vanillyl-mandelic acid as model substances. Limits of detection and determination are 2.2 and 6.6 mu mol L-1, respectively. Linear range was 2.2-100 mu molL(-1), repeatability 1.34% (n = 10).
Keywords:
biomarkers; boron doped diamond film; voltammetry
Available at various institutes of the ASCR
Miniaturized boron doped diamond film electrode for neuroblastoma biomarkers determination
Cathodically pretreated miniaturized boron doped diamond film electrodewas successfully tested for the purposes of in-situ determination of neuroblastoma biomarkers after hollow-fibre based ...
The intrinsic submicron ZnO thin films prepared by reactive magnetron sputtering
Remeš, Zdeněk; Stuchlík, Jiří; Purkrt, Adam; Chang, Yu-Ying; Jirásek, Vít; Štenclová, Pavla; Prajzler, V.; Nekvindová, P.
2017 - English
The DC reactive magnetron sputtering of metallic target in oxide atmosphere is a simple method of depositing the intrinsic (undoped) nanocrystalline layers of metal oxides. We have optimized the deposition of the intrinsic ZnO thin films with submicron thickness 50-500 nm on fused silica glass substrates and investigated the localized defect states below the optical absorption edge down to 0.01 % using photothermal deflection spectroscopy from UV to IR. We have shown that the defect density, the optical absorptance and the related optical attenuation in planar waveguides can be significantly reduced by annealing in air at 400 °C.
Keywords:
ZnO; reactive magnetron sputtering; plasma treatment; photothermal deflection spectroscopy; optical spectroscopy
Available at various institutes of the ASCR
The intrinsic submicron ZnO thin films prepared by reactive magnetron sputtering
The DC reactive magnetron sputtering of metallic target in oxide atmosphere is a simple method of depositing the intrinsic (undoped) nanocrystalline layers of metal oxides. We have optimized the ...
Hydrogen plasma treatment of ZnO thin films
Chang, Yu-Ying; Neykova, Neda; Stuchlík, Jiří; Purkrt, Adam; Remeš, Zdeněk
2017 - English
ZnO is an attractive wide band gap semiconductor with large exciton binding energy, high refractive index, high biocompatibility and diversety of nanostructure shapes which makes it suitable for many applications in the optoelectronic devices, optical sensors, and biosensors. We study the effect of hydrogen plasma treatment of the nominally undoped ZnO thin film deposited by DC reactive magnetron sputtering of Zn target in the gas mixture of argon and oxygen plasma. The SEM images show that the crystal size increases with film thickness. We confirm, that the electrical conductivity significantly increases after hydrogen plasma treatment by 4 orders of magnitude. Moreover, the increase of the infrared optical absorption, related to free carrier concentration, was detected below the optical absorption edge by the photothermal deflection spectroscopy.\n
Keywords:
ZnO; reactive magnetron sputtering; hydrogen plasma treatment
Available at various institutes of the ASCR
Hydrogen plasma treatment of ZnO thin films
ZnO is an attractive wide band gap semiconductor with large exciton binding energy, high refractive index, high biocompatibility and diversety of nanostructure shapes which makes it suitable for many ...
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