Search results for "engineering.material"
showing 10 items of 2352 documents
Thermostimulated luminescence of plasma electrolytic oxidation coatings on 6082 aluminium surface
2019
Financial support provided by Scientific Research Project for Students and Young Researchers Nr. SJZ/2016/12 realized at the Institute of Solid State Physics, University of Latvia is greatly acknowledged. Authors are grateful to R. Ignatans for measurements and analysis of XRD spectra and ElGoo Tech ltd. for providing PEO equipment.
Phase evolution by thermal treatment of equimolar cobalt–magnesium cordierite glass powders
2004
Abstract The structural evolution with annealing time at temperatures between 900 and 1100 °C of loosely compacted equimolar cobalt–magnesium cordierite glass powder was reported. The glass, with composition MgCoAl4Si5O18, was prepared by melting a glass precursor, previously synthesized by a semiwet method, at 1650 °C. Field emission scanning electron microscopy (FESEM) of isothermally heated glasses at 900 and 950 °C revealed increased phase separation with thermal treatment. X-ray diffraction (XRD) results of these powders indicated that the first crystalline phase formed was μ cobalt-containing cordierite which transformed to α cordierite with longer annealing. At the beginning of the μ…
SURFACE AND VOLUME CRYSTALLIZATION OF METALLIC GLASS (Ni50Zr50)99.9P0.1 AS INVESTIGATED BY EXOELECTRON EMISSION (EEE) AND DIFFERENTIAL THERMAL ANALYS…
2002
Surface and volume crystallization of amorphous, melt-quenched (Ni50Zr50)99.9P0.1 alloy has been investigated by measurements of the temperature dependencies of the intensity of photostimulated exoelectron emission (EEE) and by differential scanning calorimetry (DSC). A comparison of these dependencies enables one to assess the tendency of the investigated materials to premature surface crystallization. For the (Ni50Zr50)99.9P0.1 alloy the surface crystallization occurs at temperatures distinctly lower than that for the crystallization in bulk. The activation energy for the surface crystallization, determined by the Ozawa method, i.e. from the shift of EEE peak corresponding to the surface…
Outgrowth endothelial cells isolated and expanded from human peripheral blood progenitor cells as a potential source of autologous cells for endothel…
2006
One challenge of particular importance in tissue engineering is to improve vascularization of larger size defects, which would then facilitate a sufficient supply with oxygen and nutrients to the central regions of a larger tissue-engineered construct or in highly vascularized tissues. In this study, we show that outgrowth endothelial cells (OECs) derived from human peripheral blood can serve as a source of human autologous endothelial cells and can be used in combination with fibroin silk fiber meshes for applications in tissue engineering. OEC reveal a highly differentiated endothelial phenotype as well as a high phenotypic stability during their expansion. Furthermore, OEC showed very pr…
Vascularization and gene regulation of human endothelial cells growing on porous polyethersulfone (PES) hollow fiber membranes.
2004
Abstract Open-cell hollow fibers made of polyethersulfone (PES) manufactured in the absence of solvents with pore diameters smaller than 100 μm were examined for vascularization by human endothelial cells. The goal of this study was to determine whether the 3-D porous character of the PES surface affected human endothelial cell morphology and functions. Freshly isolated human endothelial cells from the skin (HDMEC), from the lung (HPMEC) and from umbilical cords (HUVEC) and two human endothelial cell lines, HPMEC-ST1.6R and ISO-HAS.c1 were added to PES fibers and cell adherence and growth was followed by confocal laser scanning microscopy. Prior coating of PES with gelatin or fibronectin wa…
Spin-Polarized Scanning Tunnelling Microscopy of Ultrathin Films
2006
Using low temperature spin-polarized scanning tunneling microscopy we have studied the morphology and magnetic properties of ultrathin Fe(0.5 ML)Au(0.5 ML) nanowires prepared on a Mo(110) single crystal. The Fe nanostripes grown by step flow on a Mo(110) at 700 K were covered by Au at RT, and subsequently annealed at 700 K. Differences in the morphology of Au on Fe(110)/Mo(110) and clean Mo(110) surfaces are observed and discussed. After annealing, the Mo is covered by a homogeneous FeAu ML alloy with several iron enriched islands which reveal an out-of-plane magnetic contrast. Direct lateral exchange coupling has been observed for these islands.
Influence of Co content on structural and magnetic properties of CoxFe84−xNb7B9 alloys
2003
Nanocrystallization of CoxFe84� xNb7B9 (x ¼ 17; 25, 33) alloys has been studied. Crystallization of specimens starts above 4501C. After annealing of specimens in the range 500–7001C, apart from amorphous component and BCC Fe-Co alloy, a non-magnetic component also appears, which is attributed to (Fe1� xCox)2Nb phase with a relative area of about 14%. Decrease of quadrupole splitting with annealing temperature indicates some possible ordering of the nonmagnetic phase. r 2002 Elsevier Science B.V. All rights reserved.
Processing and properties of nanocrystalline Pb(Sc0.5Ta0.5)O3, Pb(Sc0.5nb0.5)O3 and Pb(Mg1/3Nb2/3)O3 films produced by RF-sputtering from ceramic tar…
2000
Abstract Nanocrystalline thin films of different relaxor materials, namely Pb(Sc0.5Ta0.5)O3 (PST), Pb(Sc0.5Nb0.5)O3(PSN), Pb(Mg1/3Nb2/3)O3(PMN) have been produced by RF-sputtering to investigate whether it will affect their dielectric properties if their grain size is reduced to the dimensions known from their nanodomains. The XRD shows that the amorphous film crystallizes in pyrochlore structure at lower temperatures and short times. Annealing at higher temperatures and far longer time intervals leads to an increasing amount of perovskite phase with a grain size in the nanometer range. These results including dielectric measurements will be presented and discussed.
Fast-neutron-induced and as-grown structural defects in magnesium aluminate spinel crystals with different stoichiometry
2019
Abstract Several hole-type paramagnetic defects (a hole localized at a regular oxygen ion near charged structural defect/defects) have been revealed in fast-neutron-irradiated MgO⋅2.5Al2O3 single crystals using the EPR method. Three of them (a dominant V1 and small amount of V2 and V22) were recently revealed in a neutron-irradiated stoichiometric MgAl2O4, while a novel V4 center, ascribed to a hole in a form of O− ion nearby a complex of a magnesium vacancy and a positively charged antisite defect (V4 ≡ O–‑VMg‑Al|Mg), was created by fast neutrons only in a nonstoichiometric single crystal. The pulse annealing of the EPR signal of these centers was compared to that of radiation induced opti…
CEMS Study of 57Fe Implanted in Diamond
2002
Conversion electron Mossbauer (CEMS) measurements have been made on a diamond sample implanted with 70 keV 57Fe to a dose of 5 × 1014 cm−2. CEMS spectra were collected in the as-implanted state and after annealing the diamond up to 1470 K. The lower temperature spectra were consistently fitted with three symmetric doublets. With annealing the areal fractions of two of the doublets increased to 44% and 48 %, respectively, while that of the third doublet decreased to be replaced by a single line component with isomer shift δ = 0.0 mm/s. Comparison of the observed isomer shifts with recent in-beam Mossbauer measurements and theoretical calculations allow us to attribute the singlet to intersti…