Gravity spun polycaprolactone fibres for soft tissue engineering:interaction with fibroblasts and myoblasts in cell culture

Poly(ε-caprolactone) (PCL) fibres were produced by wet spinning from solutions in acetone under low shear (gravity flow) conditions. As-spun PCL fibres exhibited a mean strength and stiffness of 7.9 MPa and 0.1 GPa, respectively and a rough, porous surface morphology. Cold drawing to an extension of 500% resulted in increases in fibre strength (43 MPa) and stiffness (0.3 GPa) and development of an oriented, fibrillar surface texture. The proliferation rate of Swiss 3T3 mouse fibroblasts and C2C12 mouse myoblasts on as-spun, 500% cold-drawn and gelatin-modified PCL fibres was determined in cell culture to provide a basic measure of the biocompatibility of the fibres. Proliferation of both cell types was consistently higher on gelatin-coated fibres relative to as-spun fibres at time points below 7 days. Fibroblast growth rates on cold-drawn PCL fibres exceeded those on as-spun fibres but myoblast proliferation was similar on both substrates. After 1 day in culture, both cell types had spread and coalesced on the fibres to form a cell layer, which conformed closely to the underlying topography. The high fibre compliance combined with a potential for modifying the fibre surface chemistry with cell adhesion molecules and the surface architecture by cold drawing to enhance proliferation of fibroblasts and myoblasts, recommends further investigation of gravity-spun PCL fibres for 3-D scaffold production in soft tissue engineering. © 2005 Elsevier Ltd. All rights reserved.

Are few-mode fibres a practical solution to the capacity crunch?

In this paper, we compare the nonlinear Shannon capacity of few-mode fibre systems operating with spatial-temporal digital signal processing to the nonlinear Shannon capacity of single-mode fibre systems operating with spectral-temporal digital signal processing. Combining these results with estimates of digital signal processing complexity for each option offers valuable insights to system designers.

The nonlinear Shannon limit and the need for new fibres

This paper will review the current understanding of the so called nonlinear Shannon limit, and will speculate on methods to approach the limit through new system configurations, and increase the limit using new optical fibres. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Electrocoating of carbon fibres:a route for interface control in carbon fibre reinforced poly methylmethacrylate?

A simple method of creating defined PMMA and poly (MMA-co-Cz) electrocoatings on carbon fibres is described. The electrodeposition of poly methylmethacrylate (PMMA) onto unsized, unmodified carbon fibres was performed by simple constant current electrolyses of methylmethacrylate (MMA) monomer in dimethylformamide (DMF) solutions and the 'pur' liquid monomer using sodium nitrate and lithium perchlorate as supporting electrolytes. The presence of polymeric coatings successfully attached to the carbon fibres was verified by scanning electron microscopy and photoelectron spectroscopy (XPS). Performing the electrolysis in dilute MMA in DMF solutions ([MMA]

Numerical implementation of low-PMD spun fibres with precomputed M(w) matrices

Poster With the use of the coarse-step method for simulating the phenomenon of PMD the fibre-twist as not included into the equations. This was an obstacle in representing low-PMD spun fibres numerially.

Spin transition of 1D, 2D and 3D iron(II) complex polymers - the tug-of-war between elastic interaction and a shock-absorber effect

The structures of linear chain Fe(II) spin-crossover compounds of α,β- and α,ω-bis (tetrazol-1-yl)alkane type ligands are described in relation to their magnetic properties. The first threefold interlocked 3-D catenane Fe(II) spin-transition system, [μ-tris(1,4-bis(tetrazol-1-yl)butane-N1,N1′) iron(II)] bis(perchlorate), will be discussed. An analysis is made among the structures and the cooperativity of the spin-crossover behaviour of polynuclear Fe(II) spin-transition materials.

Effect of microstructure upon elastic behaviour of human tooth enamel

Tooth enamel is the stiffest tissue in the human body with a well-organized microstructure. Developmental diseases, such as enamel hypomineralisation, have been reported to cause marked reduction in the elastic modulus of enamel and consequently impair dental function. We produce evidence, using site-specific transmission electron microscopy (TEM), of difference in microstructure between sound and hypomineralised enamel. Built upon that, we develop a mechanical model to explore the relationship of the elastic modulus of the mineral-protein composite structure of enamel with the thickness of protein layers and the direction of mechanical loading. We conclude that when subject to complex mechanical loading conditions, sound enamel exhibits consistently high stiffness, which is essential for dental function. A marked decrease in stiffness of hypomineralised enamel is caused primarily by an increase in the thickness of protein layers between apatite crystals and to a lesser extent by an increase in the effective crystal orientation angle. © 2009 Elsevier Ltd. All rights reserved.

Effect of anisotropy on elastic moduli measured by nanoindentation in human tibial cortical bone

Many biological materials are known to be anisotropic. In particular, microstructural components of biological materials may grow in a preferred direction, giving rise to anisotropy in the microstructure. Nanoindentation has been shown to be an effective technique for determining the mechanical properties of microstructures as small as a few microns. However, the effects of anisotropy on the properties measured by nanoindentation have not been fully addressed. This study presents a method to account for the effects of anisotropy on elastic properties measured by nanoindentation. This method is used to correlate elastic properties determined from earlier nanoindentation experiments and from earlier ultrasonic velocity measurements in human tibial cortical bone. Also presented is a procedure to determine anisotropic elastic moduli from indentation measurements in multiple directions. © 2001 John Wiley & Sons, Inc. J Biomed Mater Res.

Elastic and plastic properties of Mo3Si measured by nanoindentation

Single crystal Mo3Si specimens were grown and tested at room temperature using established nanoindentation techniques at various crystallographic orientations. The indentation modulus and hardness were obtained for loads that were large enough to determine bulk properties, yet small enough to avoid cracking in the specimens. From the indentation modulus results, anisotropic elastic constants were determined. As load was initially increased to approximately 1.5 mN, the hardness exhibited a sudden drop that corresponded to a jump in displacement. The resolved shear stress that was determined from initial yielding was 10-15% of the shear modulus, but 3 to 4 times the value obtained from the bulk hardness. Non-contact atomic force microscopy images in the vicinity of indents revealed features consistent with {100}(010) slip.

Nonlinear pulse shaping in fibres for pulse generation and optical processing

The development of new all-optical technologies for data processing and signal manipulation is a field of growing importance with a strong potential for numerous applications in diverse areas of modern science. Nonlinear phenomena occurring in optical fibres have many attractive features and great, but not yet fully explored, potential in signal processing. Here, we review recent progress on the use of fibre nonlinearities for the generation and shaping of optical pulses and on the applications of advanced pulse shapes in all-optical signal processing. Amongst other topics, we will discuss ultrahigh repetition rate pulse sources, the generation of parabolic shaped pulses in active and passive fibres, the generation of pulses with triangular temporal profiles, and coherent supercontinuum sources. The signal processing applications will span optical regeneration, linear distortion compensation, optical decision at the receiver in optical communication systems, spectral and temporal signal doubling, and frequency conversion. © Copyright 2012 Sonia Boscolo and Christophe Finot.

Sensing properties of germanate and tellurite glass optical fibres

Strain and thermal sensitivities of germanate and tellurite glass fibres were measured using a fibre Fabry-Perot (FFP) interferometer and fibre Bragg gratings (FBG). The strain phase sensitivity for germanate and tellurite fibre were 5900×103 rad/m and 5600×103 rad/m respectively at a central wavelength of 1540nm using FFP interferometer, which is consistent with the value of 1.22pm/µepsilon obtained for a germanate fibre FBG. The Young's modulus for germanate and tellurite fibre were also measured to be 58GPa and 37GPa. The thermal responses of germanate fibre were examined as 24.71 and 16.80 pm/°C at 1540nm and 1033nm wavelength using the FBG.

Optical chemsensors based on etched fibre Bragg gratings in D-shape and multimode fibres

We present an implementation of high-sensitivity optical chemsensors based on FBGs UV-inscribed in D-shape and multimode fibres and sensitized by HF-etching treatment, demonstrating a capability of detecting chemical concentration changes as small as < 0.5%.