.cos L K    , was developed in 1918, to calculate the nano crystallite size (L) by XRD radiation of wavelength λ (nm) from measuring full width at half maximum of peaks (β) in radian located at any 2θ in the pattern. Shape factor of K can be 0.62 -2.08 and is usually taken as about 0.89. But, if all of the peaks of a pattern are going to give a similar value of L, then .cosθ  must be identical. This means that for a typical 5nm crystallite size and λ Cukα 1 = 0.15405 nm the peak at 2θ = 170˚ must be more than ten times wide with respect to the peak at 2θ = 10˚, which is never observed. The purpose of modified Scherrer equation given in this paper is to provide a new approach to the kind of using Scherrer equation, so that a least squares technique can be applied to minimize the sources of errors. Modified Scherrer equation plots lnβ against ln(1/cosθ) and obtains the intercept of a least squares line regression, ln / K L   , from which a single value of L is obtained through all of the available peaks. This novel technique is used for a natural Hydroxyapatite (HA) of bovine bone fired at 600˚C, 700˚C, 900˚C and 1100˚C from which nano crystallite sizes of 22.8, 35.5, 37.3 and 38.1 nm were respectively obtained and 900˚C was selected for biomaterials purposes. These results show that modified Scherrer equation method is promising in nano materials applications and can distinguish between 37.3 and 38.1 nm by using the data from all of the available peaks.

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One of the major challenges facing researchers of tissue engineering is scaffold design with desirable physical and mechanical properties for growth and proliferation of cells and tissue formation. In this research, firstly, nano-bioglass powder with grain sizes of 55-56 nm was prepared by melting method of industrial raw materials at 1,400 °C. Then the porous ceramic scaffold of bioglass with 30, 40 and 50 wt% was prepared by using the polyurethane sponge replication method. The scaffolds were coated with poly-3-hydroxybutyrate (P3HB) for 30 s and 1 min in order to increase the scaffold's mechanical properties. XRD, XRF, SEM, FE-SEM and FT-IR were used for phase and component studies, morphology, particle size and determination of functional groups, respectively. XRD and XRF results showed that the type of the produced bioglass was 45S5. The results of XRD and FT-IR showed that the best temperature to produce bioglass scaffold was 600 °C, in which Na2Ca2Si3O9 crystal is obtained. By coating the scaffolds with P3HB, a composite scaffold with optimal porosity of 80-87% in 200-600 μm and compression strength of 0.1-0.53 MPa was obtained. According to the results of compressive strength and porosity tests, the best kind of scaffold was produced with 30 wt% of bioglass immersed for 1 min in P3HB. To evaluate the bioactivity of the scaffold, the SBF solution was used. The selected scaffold (30 wt% bioglass/6 wt% P3HB) was maintained for up to 4 weeks in this solution at an incubation temperature of 37 °C. The XRD, SEM EDXA and AAS tests were indicative of hydroxyapatite formation on the surface of bioactive scaffold. This scaffold has some potential to use in bone tissue engineering.

Abstract. The aim of this study is to evaluate the e ects of Multi-Walled Carbon NanoTubes (MWNTs) on the structural and mechanical properties of poly-3-hydroxybutyrate (P3HB) electrospun sca olds. To achieve optimal properties of the electrospinning machine, P3HB polymer solutions were prepared at di erent concentrations and spinned in di erent electrospinning parameters. After optimization, MWNTs in di erent weight percentages (0.5%, 0.75%, 1%, and 1.25%) were added to the polymer solutions and electrospinned. The e ects of MWNTs on the structure of bers were investigated using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR) techniques. The addition of MWNTs increased the average ber diameter from 210 (neat P3HB) to 700 nm at 1.25% MWNTs. In addition, SEM photomicrographs and the MATLAB software program showed an increase in porosity from 81% to 84% in the presence of MWNTs. Tensile strength of P3HB/MWNTs composites revealed 158% improvement over pure P3HB sca old. According to mechanical and structural properties, the best amount of MWNTs was 0.5 wt%. Therefore, MWNTs with low percentages can signi cantly improve the mechanical properties of pure P3HB sca old, so that they can become favorable mechanically for tissue engineering applications.

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