Hydroxyapatite/cellulose acetate composite webs were fabricated by an electro-spinning process. This electro-spinning process makes it possible to fabricate complex three-dimensional shapes. Nano fibrous web consisting of cellulose acetate and hydroxyapatite was produced from their mixture solution by using an electro-spinning process under high voltage. The surface of the electro-spun fiber was modified by a plasma and alkaline solution in order to increase its bioactivity. The structure, morphology and properties of the electro-spun fibers were investigated and an in-vitro bioactivity test was evaluated in simulated body fluid (SBF). Bioactivity of the electro-spun web was enhanced with the filler concentration and surface treatment. The surface changes of electro-spun fibers modified by plasma and alkaline solution were investigated by FT-IR (Fourier Transform Infrared Spectroscopy) and XPS (X-ray Photoelectron Spectroscopy).
Formation and characterization of hydroxyapatite-based porous ceramics derived from polymer pyroysis were investigated. Polymer based process is chosen for preparing porous hydroxyapatite-based ceramics having a high mechanical strength. The hydroxyapatite-based porous ceramic was prepared by a self-blowing process of a polymethylsiloxane with filler and pyrolyzed at above 1000 o C. Biphasic material consisted of hydroxyapatite and CaO has been prepared by solid state reaction from calcium hydroxide(Ca(OH) 2) and calcium hydrogen phosphate dihydrate(CaHPO 4 •2H 2 O) as a filler material. The influence of filler content on mechanical properties was evaluated. The change of crystalline phase, microstructure and mechanical properties were investigated and discussed.
We have isolated two isomeric solids 1 and 2 of N,N′-bis(3,5-dichlorosalicylidene)-2,2′-ethylenedianiline and characterized by IR, UV/Vis, X-ray powder diffraction, thermogravimetric analysis/differential thermal analysis, and X-ray crystallography. Although the solids are same formulas, each shows different colors and crystal structures. Orange solid (1) shows endo conformation while yellow solid (2) exhibits exo form depending on packing modes. UV/Vis spectra of 1 and 2 appear very similar patterns in the solid state; however, the bands of 1 are slightly red-shifted compared with those of 2. 1 displays a strong fluorescent emission band at~582 nm while 2 shows an intense fluorescent signal at~563 nm. The charge density populations of 1 and 2 have been studied by computational simulations using density functional theory at pbe1pbe/6-311G** level. The calculated highest occupied molecular orbital and lowest unoccupied molecular orbital energies of 1 and 2 confirm that charge transfer occurs within the organic molecules. The energy difference of HOMO-LUMO in 1 is smaller slightly than that of 2 about 0.05 eV (~17 nm).
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