Papers by Keyword: Surface Properties

Abstract: The surface properties and iron distribution of Acidianus manzaensis YN25 grown on four different energy substrates (chalcopyrite, pyrite, S⁰, and Fe²⁺) were comparatively studied. The results showed different growth and absorption features of A. manzaensis grown on different energy substrates. Results also showed that Zeta potentials, adsorption forces and cell surface acid-base properties were significantly influenced by the growth condition. Studies based on FT-IR and UV-vis spectroscopy indicated that the differences in cell surface properties may result from the different amounts of proteins and iron distribution on the cell surface of A. manzaensis grown on different growth conditions. The SR-μ-STXM images showed that the cell surface densities of iron spread on the cells grown on chalcopyrite, pyrite, S⁰ or Fe²⁺ were 4.31×10^-5 - 23.25×10^-5 g/cm², 4.43×10^-5 - 20.24×10^-5 g/cm², 0.10×10^-5 - 0.29×10^-5 g/cm², and 6.45×10^-5 - 24.06×10^-5 g/cm², respectively, further indicating that the surface of A. manzaensis cells grown on chalcopyrite, pyrite and Fe²⁺ had an iron-contained compounds, which might be the reason why the surface of A. manzaensis cells grown on chalcopyrite, pyrite and Fe²⁺ carried weak positive charges at pH 2 while negative for the cells grown on S⁰.

Abstract: Bonding has experienced an enormous expansion in the various applications during the last few years in the field of material joining, due to which it is classified as a new joining technology, although it is, in fact, very old. Compared with the conventional joining methods (riveting, screwing and welding), bonding provides a new material combination possibilities and it allows us to obtain special shapes and properties, which can not be formed by conventional methods. To create a high-quality bonded joint, it is important to wet the bonded surface very well wetted by a wetting liquid. The wettability of the material is characterized by a contact angle of wetting, by which the surface energy is subsequently determined. For a high quality of the joint, the bonded material must have higher surface energy than the witting liquid (adhesive) [1-3]. This paper describes the effect of plasma surface treatment on the surface properties (surface energy, microhardness) of low-density polyethylene (LDPE) and high-density polyethylene (HDPE), and also on the final strength of bonded joints. The measured results indicate, that plasma surface treatment is very effective tool for improvement of surface properties and strength of bonded joints of HDPE and LDPE. The strength of bonded joints after plasma surface treatment was increased up to 350 % compared to untreated material. A similar trend was observed even for surface energy and microhardness of materials.

Abstract: In situ TiO₂ nanofiber arrays have been successfully produced directly on a Ti-6Al-4V substrate by using thermal oxidation under a limited supply of oxygen. Their morphology, elemental composition, crystal structure, surface roughness and surface wettability were characterized by field-emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffractometer (XRD), atomic force microscope (AFM) and contact angle goniometer, respectively. The results of material characterization studies revealed that TiO₂ nanofibers possessed greater surface roughness and wettability, as well as the degree of crystallinity. In vitro characterization have also been evaluated by using bovine articular chondrocytes on the resulting TiO₂ nanofibrous surface at different time points. Cell adhesion was observed qualitatively by using FESEM and cell proliferation was determined quantitatively by using AlamarBlue reduction assay. The results showed that the TiO₂ nanofibrous substrate triggers enhanced chondrocytes adhesion, proliferation, and production of extracellular matrix (ECM) fibrils compared to untreated substrate. These results suggest that the oxidation process produces a surface structure to which chondrocytes affinity, and thus this surface would has potential use in implants designed for cartilaginous applications.

Abstract: This work concerns the changes to wood surface morphology induced by surface cleaning with dry ice. The surface roughness values demonstrated that the surface treatment with dry ice resulted in amplified surface roughness, mainly due to the increase in the roughness of early wood. The treatment of old wood with dry ice not only guarantees effective removal of contamination from the wood surface, it also induces positive changes in other (such as wettability, surface free energy, color, and similar). This way of wood surface treatment guarantees more wood surface quality for the surface treatment, impregnation or gluing.

Abstract: In order to meet the requirements of large-scale industrial production, a hybrid sol-gel route which was used to fabricate PZT thick film attract a lot due to its low price [1]. However, surface imperfections, such as crack, pore and thickness nonuniform must be controlled. In this work, in order to get perfect film additive such as formylamine, acetic acid, polyvinylpyrrolidone (PVP) were studied. The surface morphologies were characterized by the Dimension 3100 atomic force microscope (AFM) and the Quanta 400 FEG Field emission environmental scanning electron microscope (SEM) respectively. The effect of additives on film thickness was studied by the JA.Woollam MD2000D Elliptic polarization spectrometer. The results show us that the additive can improve the the defects such as crack, porous and thickness nonuniform of PZT films effectively. We got crack-free, nonporous and compact PZT piezoelectric films when the PZT sol was acetic acid 20%, formylamine 15% and PVP 1% inside.

Abstract: This Chapter is focused on the Ti-Nb-based shape memory alloys for biomedical applications; the principal objective being to understand interrelations between structure and transformation features, static and dynamic functional properties, and conditions of their thermomechanical treatment. This Chapter includes also preliminary study of the surface characteristics of Ti-Nb-based alloys, including their elemental and phase compositions, tribological characteristics, wettability, electrochemical behaviour, and in vitro biocompatibility. The results obtained make it possible to conclude that Ti-Nb-based shape memory alloys represent one of the strongest candidates for a new generation of load-bearing orthopaedic or dental implants with improved biocompatibility, since they combine high biomechanical compatibility of Ti-Ni shape memory alloys with excellent biochemical compatibility of pure titanium.

Abstract: Ultrasonic shot peening (USP) on AALY12 sheet was studied. Several parameters (arc heights, surface roughness, surface topography and micro hardness) with different USP process parameters were measured. The research proposes that radius of curvature of shot peened sheet increases with time and electric current decreasing, while increases with pin diameter increasing, and radius of curvature reaches a saturation level after a specific processing time and electric current. An empirical model of the relationship between radius of curvature and pin diameter, electric current, time was also obtained. The research shows that the increment of surface and vertical micro hardness of material is more obvious with longer time and higher value of electric current, which can be up to 20% and 28% respectively.

Abstract: The surfaces of building materials are constantly exposed to the actions of environmental factors, pollutants of inorganic and organic origin as well as to microorganisms, which significantly contribute to corrosion phenomena.The application of coatings decreases the negative action of the pollutants minimizing their direct contact with the substrate. Different types of coatings with additional functions have been developed. A specific problem of these applications is the lack of compatibility of the photocatalysts with the surface of the building materials and the detachment of potentially toxic TiO₂ nanoparticles. In the present study, this problem was solved by the proper immobilization of TiO₂ nanoparticles onto the photocatalyst support, layered double hydroxides (LDHs). The newly formed coating possesses acceptable porosity for a porous building material (porosity within the range of 30-46 %) and satisfied photocatalytic activity, as well as mineralogical compatibility with the substrates (mortars, renders, bricks). Additionally, a positive effect considering the self-cleaning phenomenon was attained.

Abstract: Titania nanofiber (TiO₂ NFs) arrays were fabricated in situ on a Ti-6Al-4V substrate by an oxidation process. Their surface morphology, crystallographic structure, surface roughness and wettability were characterized, as well as their in vitro interaction with bovine articular chondrocytes at different time points. Results showed that TiO₂ NFs possessed greater surface roughness, hydrophilicity and degree of crystallinity. The in vitro cell studies revealed that TiO₂ NFs substrate triggers enhanced cell adhesion, proliferation and extracellular matrix (ECM) formation compared to the untreated control sample. These results showed that chondrocytes have an affinity to the nanofibrous substrate surface and thus we suggest that such surfaces are suited to be used as an implant designed for cartilage growth.

Abstract: Radiation cross-linking gives inexpensive commodity plastics and technical plastics the mechanical, thermal, and chemical properties of high-performance plastic. This upgrading of the plastics enables them to be used in conditions which they would not be able to with stand otherwise. The irradiation cross-linking of thermoplastic materials via electron beam or cobalt 60 (gammy rays) is performed separately, after processing. Generally, ionizing radiation includes accelerated electrons, gamma rays and X-rays. Radiation processing with an electron beam offers several distinct advantages when compared with other radiation sources, particularly γ-rays and x-rays. The process is very fast, clean and can be controlled with much precision. There is no permanent radioactivity since the machine can be switched off. In contrast to γ-rays and x-rays, the electron beam can steered relatively easily, thus allowing irradiation of a variety of physical shapes. The energy-rich beta rays trigger chemical reactions in the plastics which results in networking of molecules (comparable to the vulcanization of rubbers which has been in industrial use for so long). The energy from the rays is absorbed by the material and cleavage of chemical bonds takes place. This releases free radicals which in next phase from desired molecular bonds. This article describes the effect of radiation cross-linking on the surface and adhesive properties of low-density polyethylene.