Advanced Materials Research Vols. 123-125

Abstract: The main objective of this work is to make an absorbable monofilament suture from Thai rice starch. The improvement of the mechanical properties of Thai rice starch polymer films were achieved by addition of small amount of gelatin, carboxymethylcellulose (CMC) and carbon nanopowders. The carbon nanopowders were produced from coconut shell in our laboratory room by milling method. The incorporation of carbon nanopowders with a high aspect ratio and/or an extremely large surface area into Thai rice starch polymer films improves their mechanical performances significantly. Additionally, the black color from carbon nanopowder is easily visualized in tissue during surgery. The manufacturing processes are very simple by blending of the raw materials in hot water and then dry heating in electric oven. The final product was characterized of microstructures and mechanical properties. The resulting Thai rice starch-carbon nanocomposites possess several advantages for manufacture of sutures: 1. high water resistance that can be uses in the human body. 2. high mechanical strength that appropriate to manufacture of sutures. 3. biocompatibility and bioabsorbable. 4. low cost. 5. Eco-friendly green nanocomposites. However, the method of size designation of sutures fibers and needle attachment are the problem which restricts our suture in really applications. The investigation of knowledge and simple technology of manufacture of suture and needle attachment will be performed.

Abstract: Cuttlebone is a natural material possessing a unique microstructure providing a high compressive strength to weight ratio. It is potentially desirable to use cuttlebone directly in engineering applications or to design new biomimetic materials based on the microstructural features of cuttlebone. A finite element based homogenization method can be used for characterizing the mechanical properties of such a biomaterial and for the design of biomimetic materials. However, this method assumes a periodicity of microstructure, which does not reflect the variation present in natural or fabricated materials. The method can be extended to investigate the effect of natural variation and manufacturing tolerance by enlarging the base cell domain to include a number of representative volume elements (RVEs) and applying a random displacement vector to the nodes at the internal intersections of the RVEs. As the boundary of the base cell domain is not modified, the homogenization method can still be employed to calculate the bulk mechanical properties. It is found that the number of RVEs in the base cell has an impact on the decrease in mean stiffness tensor components, while the length of the introduced variation seems to influence both the mean and the standard deviation of stiffness tensor components.

Abstract: Natural bone is a composite mainly made from nano/micro-structure of hydroxyapatite and collagen fibers. For bone regeneration by tissue engineering, it is important to synthesize nano-composites with good biocompatibility, high bioactivity and great bonding property as potentially useful scaffold. In this study, we fabricated chitosan nano-nonwoven scaffold via electrospinning and modified chitosan scaffolds by carboxymethylation (CM). Moreover scaffolds were macerated in SBF (simulated body fluid) to form hydroxyapatite on its surface. Surface morphologies (SEM) showed that nano/micro particles formed on the surface of the carboxymethyl chitosan fibrous scaffold. Results of FT-IR and XRD confirmed that the nano/micro particles were hydroxyapatite crystalline. Moreover by employed mice osteoblast (MC3T3-E1) cell for adhesion, proliferation and differentiation assays, and the hydroxyapatite particles appeared to have a great effect on the late stages of osteoblast behavior (alkaline phosphatase ).

Abstract: Novel reinforcements such as beam, film, and porous frame were developed to improve the mechanical properties of poly(L-lactide) (PLLA) scaffolds. A solid-liquid phase separation method was used to fabricate porous structures such as core portions and porous frame of reinforced scaffolds. The beam and film reinforcements were also fabricated from PLLA pellets by applying the thermal-press technique. In the standard scaffold, the localized deformation was characterized as buckling of the pore structures. On the contrary, the primary microstructural deformation mechanism in the beam and the film reinforced scaffolds was characterized as buckling deformation and interfacial failure of the matrix and the reinforcement respectively. It is also seen that the inner porous structure could maintain the initial structure without local buckling of the pore structure. The compressive mechanical properties of the reinforced scaffolds were dramatically improved by about 2 ~ 5 times compared to the standard scaffold.

Abstract: The purpose of the present study was to compare the in vitro release and to findout the bioavailability of a 75 mg indomethacin capsule (Microcid®SR - reference - product A) was equivalent to optimized formulation (indomethacin loaded microspheres – test – product B). Indomethacin (IM) loaded carnauba wax fat microspheres were prepared by using meltable emulsified dispersion cooling induced solidification technique utilizing a wetting agent. Solid, discrete, reproducible free flowing microspheres were prepared. The yield of the microspheres was up to 92%, having smooth surfaces, with free flowing and good packing properties, angle of repose, % Carr’s index and tapped density values were within the limit. More than 98.0% of the isolated spherical microspheres were in the particle size range of 1135 - 1360 mm were confirmed by scanning electron microscopy (SEM). The drug loaded in microspheres was stable and compatible, as confirmed by DSC and FTIR studies. A single dose, randomized, complete cross over study of IM (75 mg) microspheres was carried out on 10 healthy male and female Albino sheep’s under fasting conditions. The plasma was separated and the concentrations of IM were determined by HPLC-UV method. Plasma IM concentrations and other pharmacokinetic parameters obtained were statistically analyzed. Based on this study, is it possible to conclude that drug loaded microspheres and Microcid®SR capsule are bioequivalent in terms of the rate and extent of absorption.

Abstract: This paper is concerned with plant biomechanics to obtain inspiration for innovative engineering technology from nature. The dynamics of the flower head movement and the plant growth was studied experimentally. The folding and unfolding movements of the petals of cut dandelion flower heads were observed by the low-speed photographing method. Movements of cut dandelion flower heads were observed as movies, and analyzed by the personal computer. The surface cell form of the petal of the dandelion, Taraxacum officinale, was also observed by the laser beam microscope. The time change of the surface form of petal cells was clarified.

Abstract: Coronary stents have been more and more widely used in clinic over the past decade. There have been a large number of stents made of different biocompatible materials available commercially in the market. It is however unclear which is more suitable to specific patients. This raises a major concern whether the choice of stents could be assessed before a delivery surgery. This paper aims to provide a computational approach for evaluating the effect of stent materials on biomechanical outcomes of the deployments of stents in different patient. It will review the typical biomaterials being used for coronary stents, seeking to qualitatively assess them for use as coronary stents. Non-linear explicit finite element (FE) procedure is carried out using the Palmaz-Schatz stent geometry to quantitatively predict the effect of mechanical properties of these biomaterials on stent and coronary artery behavior during stent deployment. A quantitative comparison is made for exploring the effect of different materials on the deployment of stents. The study is considered significant in understanding the role how stent materials affect biomechanical responses to the coronary stenting. It provides a new methodology to promote a patient-specific assessment before surgery.

Abstract: The polymerization shrinkage of light-cured composite resin, a dental restoration material, was studied using three different experimental methods. Digital image correlation method was used to examine the shrinkage deformation on the free surface of artificial cylindrical cavities. X-ray CT images and the digital image correlation were employed to measure the shrinkage deformation in the cavities. The shrinkage force was measured at the floor of the cavity using a load-cell, and evaluated as functions of time and the depth of the cavity.

Abstract: Poly(linalool) thin films were fabricated using RF plasma polymerisation. All films were found to be smooth, defect-free surfaces with average roughness of 0.44 nm. The FTIR analysis of the polymer showed a notable reduction in –OH moiety and complete dissociation of C=C unsaturation compared to the monomer, and presence of a ketone band absent from the spectrum of the monomer. Poly(linalool) were characterised by chain branching and a large quantity of short polymer chains. Films were optically transparent, with refractive index and extinction coefficient of 1.55 and 0.001 (at 500 nm) respectively, indicating a potential application as an encapsulating (protective) coating for circuit boards. The optical band gap was calculated to be 2.82 eV, which is in the semiconducting energy gap region.

Abstract: Successful human tissue adhesives depend on sure parameters which cannot be matched by any one adhesive. In this work, the novel human tissue adhesive is fabricated from gelatin and coconut shell carbon nanopowder composite. Characteristics of the carbon powder and the product samples were then investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM). Mechanical characterization and tissue adhesive bonding test of the final product were also performed.