Bio-Medical Materials and Engineering - Volume 15, issue 5

Authors: Wan, Tao | Li, Shipu | Zhou, Wenjuan | Yan, Yuhua | Li, Jianhua | He, Jianhua

Article Type: Research Article

Abstract: In this paper, preparation technologies for the compound fibers of poly D,L-lactic acid (PDLLA)/hydroxyapatite (HA) were investigated. Starting with PDLLA of weight average molecular mass 94,200–1,130,000 and HA powders of diameter 4–10 μm, the compound fibers of PDLLA/HA were obtained through a two stage process: first the adsorption of HA particles on the surface of PDLLA flakes using the liquid-phase adsorption method then melt-extrusion, and second the spinning collection. Experimental result was showed that the high performance composite fibers of PDLLA/HA with diameter of 15–30 micrometer could be produced by the PDLLA of weight average molecular mass 150,000–300,000, the HA …powders content 5 wt%, the melt extrusion temperature below 160°C and the screw rotating speed of 10–15 r/min, the spinning collection speed of 2–5 m/min. Show more

Keywords: PDLLA/HA, composite fiber, melt-extrusion, spinning collection, SEM

Citation: Bio-Medical Materials and Engineering, vol. 15, no. 5, pp. 333-339, 2005

Authors: Tang, C.Y. | Stojanovic, B. | Tsui, C.P. | Kojic, M.

Article Type: Research Article

Abstract: A new model incorporating muscle fatigue has been developed to predict the effect of muscle fatigue on the force–time relationship of skeletal muscle by using the PAK-program. Differential equations in the incremental form have been implemented into Hill's muscle model. In order to describe the effect of muscle fatigue and recovery on skeletal muscle behaviors, a set of equations in terms of three phenomenological parameters which are a fatigue curve under sustained maximal activation, a recovery curve and an endurance function were developed. With reference to existing models and experimental results, the input parameters for fatigue curve under sustained maximal …activation and endurance function were determined. The model has been investigated under an isometric condition. The effects of different shapes of the recovery curves have also been considered in this model. Validation of the model has been performed by comparing the predicted results with the experimental data from an existing literature. Show more

Keywords: Muscle model, muscle fatigue, fatigue, recovery, hill, prediction, maximal effort

Citation: Bio-Medical Materials and Engineering, vol. 15, no. 5, pp. 341-348, 2005

Authors: Janna, Sied | Dwiggins, David P. | Lewis, Gladius

Article Type: Research Article

Abstract: In cases where the Weibull probability distribution is being investigated as a possible fit to experimentally obtained results of a random variable (V), there is, currently, no accurate and reliable but simple-to-use method available for simultaneously (a) establishing if the fit is of the two- or three-parameter variant of the distribution, and/or (b) estimating the minimum value of the variable (V0 ), in cases where the three-parameter variant is shown to be applicable. In the present work, the details of such a method – which uses a simple nonlinear regression analysis – are presented, together with results of its use …when applied to 4 sets of number-of-cycles-to-fracture results from fatigue tests, performed in our laboratory, using specimens fabricated from 3 different acrylic bone cement formulations. The key result of the method is that the two- or three-parameter variant of the probability distribution is applicable if the estimate of V0 obtained is less than or greater than zero, respectively. Show more

Keywords: Weibull relationship, acrylic bone cement, fatigue

Citation: Bio-Medical Materials and Engineering, vol. 15, no. 5, pp. 349-355, 2005

Authors: Domingo, S. | Puértolas, S. | Gracia-Villa, L. | Mainar, M. | Usón, J. | Puértolas, J.A.

Article Type: Research Article

Abstract: We have designed, manufactured and evaluated a prototype of a new stent based on the superelasticity of the NiTi alloy for colon obstruction, which is the first clinical manifestation of colorectal cancer in up to 29% of cases. The stent is auto-expandable diamond cell type, manufactured from a NiTi tube with 4.5 mm in diameter, in which longitudinal grooves were performed by cutting laser technique. The expansion process to the final shape was made by deformation in the martensite state. The stent reaches a high free expansion rate of 7, with a longitudinal variable radial strength and a bell-shaped profile …in the extremes in order to avoid migration. Finite elements models were used for simulating the mechanical behaviour. The prototype was evaluated by implantation in a colon stenosis model of 6 mm in diameter performed in a porcine speciment. The stent gave a good deployment, fixation and capability to open the gap up to 15 mm in diameter. Show more

Keywords: Stent, colon, NiTi, Nitinol, shape memory alloys, stenosis

Citation: Bio-Medical Materials and Engineering, vol. 15, no. 5, pp. 357-365, 2005

Authors: Mathieu, Jean-Baptiste | Martel, Sylvain | Yahia, L'Hocine | Soulez, Gilles | Beaudoin, Gilles

Article Type: Research Article

Abstract: The Magnetic Resonance Submarine (MR-Sub) project is a first attempt to validate a new propulsion method for future small magnetically controlled microdevices suited for minimally invasive applications in blood vessels. A Magnetic Resonance Imaging (MRI) system provides the driving force in three dimensions to a ferromagnetic core that could be embedded onto a specialised microdevice. The paper describes preliminary tests made to match the magnetic force induced by an MRI system on a ferromagnetic sphere with the drag force it encompasses in a cylindrical tube. These tests provide a proof of concept demonstrating that this new method of propulsion is …very promising within the constraints of such types of operations. This conclusion is based on specific measurements showing that 1010/1020 carbon steel spheres (3.175 mm and 2.381 mm in diameter) can withstand a maximum flow of 0.370±0.0064 l/min (19.5 cm/s) and 0.311±0.01209 l/min (16.4 cm/s) respectively when placed inside a 6.35 mm diameter PMMA tube and subjected to a 18 mT/m magnetic field gradient. Show more

Keywords: Magnetic resonance imaging, microdevice, magnetic propulsion

Citation: Bio-Medical Materials and Engineering, vol. 15, no. 5, pp. 367-374, 2005

Authors: Cai, H. | Azangwe, G. | Shepherd, D.E.T.

Article Type: Research Article

Abstract: Tissue engineering, where cells attach and grow on a scaffold, has the potential to produce replacement ears made from natural tissues and replace the need for rubber prosthetic ears. This study investigated the feasibility of using the rapid prototyping technique of Fused Deposition Modelling (FDM) to produce an ear-shaped scaffold. A three-dimensional image of the ear was used to manufacture ear-shaped scaffolds from ABS (acrylonitrile/butadiene/styrene) plastic using FDM. Human dermal fibroblasts were seeded on the scaffold (coated with fibronectin) to attach and grow in culture medium in an incubator for two weeks. Human keratinocytes were then seeded on to the …fibroblast layer to attempt to produce a more realistic skin covering. The morphology of the cells were observed using scanning electron microscopy. The results show that a realistic ear-shaped scaffold can be made using FDM. Human fibroblasts were found to attach and grow. Human keratinocytes were successfully attached and grown on top of the fibroblasts and this resulted in a skin covering over the scaffold. This study shows that FDM has great potential as a manufacturing technique for ear-shaped scaffolds for tissue engineering. Show more

Keywords: Cell culture, ear, fibroblast, keratinocyte, rapid prototyping, tissue engineering

Citation: Bio-Medical Materials and Engineering, vol. 15, no. 5, pp. 375-380, 2005

Authors: Tomihata, Kenji | Suzuki, Masakazu | Tomita, Naohide

Article Type: Research Article

Abstract: A monofilament suture made of poly(L-lactide-co-ε-caprolactone) was examined by several mechanical tests to evaluate handling characteristics for tight tying. Six types of other monofilament sutures were also examined for comparisons. Two of these were nonabsorbable, while the others were absorbable sutures. Sutures consisting of glicolide were strongest among all the sutures examined. On the other hand, PROLENE and P(LA/CL) sutures showed high knot-pull strength despite low straight pull strength. Untying performance was evaluated by viscoelasticity, bending plasticity and tying test. A good correlation between tan δ and bending plasticity index was observed and the poly(L-lactide-co-ε-caprolactone) suture exhibited high tan δ, high bending …plasticity and good resistance against untying. Show more

Keywords: Suture, monofilament, handling characteristics, knot

Citation: Bio-Medical Materials and Engineering, vol. 15, no. 5, pp. 381-391, 2005

Authors: Saupe, Anne | Wissing, Sylvia A. | Lenk, Andreas | Schmidt, Corinna | Müller, Rainer H.

Article Type: Research Article

Abstract: Two different types of colloidal lipid particles are presented and compared as innovative carrier systems. Size distribution and storage stability of formulations produced by hot high pressure homogenisation in lab and medium scale production were investigated by laser diffractometry (LD) and photon correlation spectroscopy (PCS). Nanoparticles were characterised by their melting and recrystallisation behaviour recorded by differential scanning calorimetry (DSC). Electron microscope investigations were also carried out showing the particulate character of these carriers. Reasons for observed differences in loading capacity are discussed and possibilities for dermal application are described.

Keywords: SLN, NLC, physical stability, loading capacity, particulate character, scaling up feasibility

Citation: Bio-Medical Materials and Engineering, vol. 15, no. 5, pp. 393-402, 2005