Mechanical and bioactivity assessment of wollastonite/PVA composite synthesized from bentonite clay

Glass/polymer composites can mimic the natural structure of bone by possessing a fiber-matrix configuration which provides appropriate physical and biological properties. Wollastonite ceramics are known for their promising bioactivity and biocompatibility when applied in bone regeneration. Polyvinyl alcohol (PVA) has various attractive properties including biocompatibility and degradability which may be exploited as a polymer matrix in composites for biomedical applications. Therefore, a cost-effective method of preparing wollastonite/PVA composites is desirable by starting from bentonite clay as a silica source for the glass, instead of traditional alkoxysilanes. The composite prepared was characterized by mechanical testing, scanning electron microscopy, X-ray diffractometry and Fourier-transform infrared spectroscopy to evaluate its compressive strength, morphology, phase composition and bioactivity, respectively. Results obtained revealed for the composite a compressive strength of 0.3 MPa, the ability to induce apatite on its surface when immersed in a simulated body fluid for 7 days and desirable controlled degradation. Hence, this method can be up-scaled for preparation of wollastonite/PVA composite commercially for possible use in bone regeneration.

Experimental investigation on air-side flow-field and water-side heat exchange performance of radiator based on matrix fans

This paper investigated the effect of four different fan matrix configurations on the air-side flow-field and water-side heat exchange performance of a radiator. With the introduction of fan matrix configurations, the wake region behind bumper beam is enlarged, and the vortex pair breaks up much rapidly, thus enhancing the turbulence intensity of wake. The vorticity reaches the minimum level under the fan matrix N = 6, which could reduce the energy loss of the airflow upstream of radiator. The fan matrix configuration can increase the velocity uniformity of the airflow passing through the radiator, especially for the fan matrix N = 6. Furthermore, due to the fan matrix N = 6 achieves the maximum heat dissipation uniformity of radiator, and it also achieves the best heat exchange performance. Consequently, to achieve the maximum cooling air mass flow rate and heat exchange performance, it should carry out an optimization process during the design phase of fan matrix.

Matrix Arrangement of Three-Dimensional Sheath Flow for Multiple Component Nanofibers

Multiple core-sheath flow was realized using matrix arrangement of 3D sheath flows. The sheath flow was hydrodynamically formed in a flow shift area which has symmetrical microgrooves on channel walls. Vertical and horizontal alignments of the sample streams are a key element of matrix configuration. The flow shift areas were connected in parallel to achieve horizontal alignment of the sheath flow. The cascade connection of the flow shift areas is used for vertical alignment of the sheath flow. In order to achieve matrix arrangement of core-sheath flow, combination of the parallel and cascade connections was utilized. In this work, the horizontal and vertical configurations of the 2-sample sheath flow were demonstrated. Two streams of the vertically aligned 2-sample sheath flow were joined horizontally, and, as a result, 4-sample core-sheath flow of matrix configuration was obtained successfully.

Mathematical Modeling of Polymer Biodegradation and Erosion

The biodegradable polymers are widely used in therapeutic surgery and pharmaceutics, in which the degradation process has drawn significant attention in recent years. In this paper, we propose a mathematical model to predict the polymer degradation in tissue engineering applications. A stochastic model is introduced to characterize the hydrolysis reaction in an elemental basis and the mass transport is also performed to investigate the diffusive transport of polymer erosion. Two representative polymeric films in different configurations are studied. It is found that for biodegradable systems, mass transport plays an important role in controlling the erosion pathway, in which the matrix configuration could be one of the key factors that determine the characteristics of erosion and drug release rates. The proposed model makes a useful benefit to the design optimization of the matrix architectures for biodegradable devices.

Inherited complex I deficiency is associated with faster protein diffusion in the matrix of moving mitochondria

Mitochondria continuously change shape, position, and matrix configuration for optimal metabolite exchange. It is well established that changes in mitochondrial metabolism influence mitochondrial shape and matrix configuration. We demonstrated previously that inhibition of mitochondrial complex I (CI or NADH:ubiquinone oxidoreductase) by rotenone accelerated matrix protein diffusion and decreased the fraction and velocity of moving mitochondria. In the present study, we investigated the relationship between inherited CI deficiency, mitochondrial shape, mobility, and matrix protein diffusion. To this end, we analyzed fibroblasts of two children that represented opposite extremes in a cohort of 16 patients, with respect to their residual CI activity and mitochondrial shape. Fluorescence correlation spectroscopy (FCS) revealed no relationship between residual CI activity, mitochondrial shape, the fraction of moving mitochondria, their velocity, and the rate of matrix-targeted enhanced yellow fluorescent protein (mitoEYFP) diffusion. However, mitochondrial velocity and matrix protein diffusion in moving mitochondria were two to three times higher in patient cells than in control cells. Nocodazole inhibited mitochondrial movement without altering matrix EYFP diffusion, suggesting that both activities are mutually independent. Unexpectedly, electron microscopy analysis revealed no differences in mitochondrial ultrastructure between control and patient cells. It is discussed that the matrix of a moving mitochondrion in the CI-deficient state becomes less dense, allowing faster metabolite diffusion, and that fibroblasts of CI-deficient patients become more glycolytic, allowing a higher mitochondrial velocity.