89 research outputs found
Modyfikacja powierzchni stopu Ti-6Al-4V metodą PEO-EPD w zawiesinie ZrSiO4
Investigations on the surface modification of the Ti-6Al-4V alloy by plasma electrolytic oxidation are reported here. The oxidation process was carried out in a solution containing a zirconium silicate (ZrSiO4) suspension and sodium hydroxide (NaOH). Anodising was realised at voltages in a range from 100 V to 250 V. It was found that the morphology of the sample surface did not change during the oxidation of the alloy at 100 V. Application of voltages higher than 100 V led to the incorporation of zirconium silicate into the formed oxide layer and to significant changes of the surface morphology
Alginate biopolymer coatings obtained by electrophoretic deposition on Ti15Mo alloy
In this work, the electrophoretic deposition method has been developed for the fabrication of bioactive alginate
coatings on the surface of Ti15Mo implant alloy. Thin ZnO lm was deposited cataphoretically as the interlayer
prior to anaphoretic deposition of alginate (Alg) which was performed from aqueous solution containing 1 g dm3
of NaAlg at room temperature. The deposition voltage and time varied in the range 20 50 V and 30 120 min,
respectively. The microstructure of Alg coatings was studied by scanning electron microscope, and the surface
roughness was analysed using atomic force microscopy. Structure was studied by grazing incidence X-ray di raction. Chemical composition and functional group were examined using energy dispersive spectrometry and attenuated total re ectance Fourier transform infrared spectroscopy methods, respectively. It was found that controlling the deposition conditions it is possible to obtain amorphous Alg coatings of variable thickness and porosity. Mechanism of electrophoretic deposition of bioactive Alg coatings on the Ti15Mo alloy surface was discussed
Modification of niobium surfaces using plasma electrolytic oxidation in silicate solutions
Herein, a study of the plasma electrolytic oxidation (PEO) of niobium in an anodising bath composed of potassium silicate (K2SiO3) and potassium hydroxide (KOH) is reported. The effects of the K2SiO3 concentration in the bath and the process voltage on the characteristics of the obtained oxide layers were assessed. Compact, barrier-type oxide layers were obtained when the process voltage did not exceed the breakdown potential of the oxide layer. When this threshold was breached, the morphology of the oxide layer changed markedly, which is typical of PEO. A significant amount of silicon, in the form of amorphous silica, was incorporated into the oxide coatings under these conditions compared with the amount obtained with conventional anodising. This surface modification technique led to an improvement in the corrosion resistance of niobium in Ringer’s solution, regardless of the imposed process conditions
Mystery of Chronic Cerebrospinal Venous Insufficiency: Identical Venographic and Ultrasound Findings in Patients with MS and Controls
Atomic and electronic structure of graphene oxide/Cu interface
The results of X-ray photoemission (XPS) and valence bands spectroscopy,
optically stimulated electron emission (OSEE) measurements and density
functional theory based modeling of graphene oxide (GO) placed on Cu via an
electrophoretic deposition (EPD) are reported. The comparison of XPS spectra of
EPD prepared GO/Cu composites with those of as prepared GO, strongly reduced
GO, pure and oxidized copper demonstrate the partial (until C/O ratio about
two) removal of oxygen-containing functional groups from GO simultaneously with
the formation of copper oxide-like layers over the metallic substrate. OSEE
measurements evidence the presence of copper oxide phase in the systems
simultaneously with the absence of contributions from GO with corresponding
energy gap. All measurements demonstrate the similarity of the results for
different thickness of GO cover of the copper surface. Theoretical modeling
demonstrates favorability of migration of oxygen-containing functional groups
from GO to the copper substrate only for the case of C/O ratio below two and
formation of Cu-O-C bonds between substrate and GO simultaneously with the
vanishing of the energy gap in GO layer. Basing on results of experimental
measurements and theoretical calculations we suggest the model of atomic
structure for Cu/GO interface as Cu/CuO/GO with C/O ratio in gapless GO about
two.Comment: 22 pages, 14 figures, accepted to Thin Solid Films journa
INFLUENCE OF PLASMA-CHEMICAL OXIDATION ON CHEMICAL COMPOSITION TANTALUM SURFACE SAMPLES
Anodization of electropolished tantalum improves the bioactive properties of the surface by increasing the thickness of the oxide layer. The results allow to select optimal conditions for treatment of metal implants. Anodizing at 20 V already sufficient to generate a sample on the surface of the oxide layer Ta2O5
Influence of electropolishing and anodic oxidation on morphology, chemical composition and corrosion resistance of niobium
The work presents results of the studies performed on electropolishing of pure niobium in a bath that contained: sulphuric acid, hydrofluoric acid, ethylene glycol and acetanilide. After the electropolishing, the specimens were subjected to anodic passivation in a 1 mol dm- 3 phosphoric acid solution at various voltages. The surface morphology, thickness, roughness and chemical composition of the resulting oxide layers were analysed. Thusly prepared niobium samples were additionally investigated in terms of their corrosion resistance in Ringer's solution. The electropolished niobium surface was determined to be smooth and lustrous. The anodisation led to the growth of barrier-like oxide layers, which were enriched in phosphorus species. © 2014 Elsevier B.V.Russian Foundation for Basic Research, RFBR: 13-08-96007; Ural Branch, Russian Academy of Sciences, UB RAS: 12-T-2-1009This work was supported by the Polish Ministry of Science and Education under the “Diamond Grant” programme, research project no. DI 2012 024142 . We acknowledge also the partial support of the Ural Division of the Russian Academy of Sciences (Project 12-T-2-1009 ) and the Russian Foundation for Basic Research (Project 13-08-96007 )
On the electropolishing and anodic oxidation of Ti-15Mo alloy
This paper presents research on modifying the surface of Ti-15Mo alloy using electropolishing and anodic passivation. The electropolishing process was carried out in solutions containing sulfuric acid, ethylene glycol, ammonium fluoride and oxalic acid. Whereas a voltage range from 20 to 100 V and a 1 M orthophosphoric acid solution were used during the anodic passivation. The influence of above mentioned processes parameters on the quality of the obtained oxide layer on Ti-15Mo alloy was investigated. The analysis of Ti-15Mo surface after modification was performed using scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), ellipsometry, and mechanical tests. Moreover, the corrosion resistance was investigated using a potentiostatic method in Ringer's solution. It was found that electropolishing leads to an increase in the surface homogeneity and to the form of an oxide layer, which consisted of TiO2 and MoO3. Whereas the oxide layers obtained during anodic passivation were characterized by different properties depending on the applied voltage. The anodic passivation at various voltages (20-100 V) increased the surface wettability (94.5°-87.6°) in comparison to the electropolished sample (97.5°). Moreover, the obtained oxide layer after anodization exhibited a high hardness. The electrolytic polishing and anodic passivation of Ti-15Mo also improved corrosion resistance of the alloy in contact with Ringer's solution. The sample anodized at 80 V presented the highest corrosion resistance by the smallest corrosion current density (1.4 nA cm-2) and the highest polarization resistance (37.4 MΩ cm2). © 2016 Elsevier Ltd. All rights reserved
Effects of supervised exercise training on lower-limb cutaneous microvascular reactivity in adults with venous ulcers
Purpose: To investigate the effects of a 12-week supervised exercise programme on lower-limb cutaneous microvascular reactivity in adults with venous leg ulceration.
Methods: Thirty-eight adults with unilateral venous ulceration who were being treated with lower-limb compression therapy (58% male; mean age 65 years; median ulcer size 5 cm2) were randomly allocated to exercise or control groups. Exercise participants (n=18) were invited to attend thrice weekly sessions of lower-limb aerobic and resistance exercise for 12 weeks. Cutaneous microvascular reactivity was assessed in the gaiter region of ulcerated and non-ulcerated legs at baseline and 3 months using laser Doppler fluxmetry coupled with iontophoresis of acetylcholine (ACh) and sodium nitroprusside (SNP). Cutaneous vascular conductance (CVC) was calculated as laser Doppler flux (AU)/mean arterial pressure (mmHg).
Results: Thirty-seven participants completed follow-up assessments. Median class attendance was 36 (range 2 to 36). Analyses of covariance revealed greater peak CVC responses to ACh in the exercise group at 3 months in both the ulcerated (adjusted difference = 0.944 AU/mmHg; 95% CI 0.504 to 1.384) and non-ulcerated (adjusted difference = 0.596 AU/mmHg; 95% CI 0.028 to 1.164) legs. Peak CVC responses to SNP were also greater in the exercise group at 3 months in the ulcerated leg (adjusted difference = 0.882 AU/mmHg; 95% CI 0.274 to 1.491), but not the non-ulcerated leg (adjusted difference = 0.392 AU/mmHg; 95% CI -0.377 to 1.161).
Conclusion: Supervised exercise training improves lower-limb cutaneous microvascular reactivity in adults with venous leg ulceration.
Keywords
Randomized controlled trial; Exercise; Ulceration; Vascular function; Laser Doppler fluxmetry; Iontophoresi
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