Arabinoxylan gels are receiving increasing attention as oral delivery systems of biomolecules for therapeutic purposes. The aim of this research was to evaluate arabinoxylan gels as an oral delivery system for insulin, representing a painless therapy for diabetics. Gels at two concentrations of arabinoxylan were prepared (2.5 and 3.5 % w/v). One concentration of insulin (0.05 % w/v) entrapped in the arabinoxylan gels was investigated. At the end of gelation elasticity (G’) values were 11 and 20 for gels at 2.5 and 3.5% (w/v) in arabinoxylan, respectively. The presence of insulin in the gels did not affect the values of G’. The apparent diffusion coefficient for insulin decreased from 1.30 x 10-7 to 1.09 x 10-7 cm2/s when the concentration of arabinoxylan in the gel increased from 2.5 to 3.5% (w/v). The percentage of proteolysis for insulin entrapped in the gels at 2.5 and 3.5% in arabinoxylan (w/v) were 35 and 17%, respectively, in relation to 100% hydrolysis of insulin in solution. Results indicate that arabinoxylan gels could be potential candidates as oral delivery systems for insulin.

The enzymatic catalyzed synthesis and gelation of an ionic peptide and its use to create hydrogels for 3D cell culture is discussed. Time resolved small angle scattering in conjunction with imaging technique allowed the structural changes occurring through this enzymatic reaction to be assessed. In turn, the structural information about the fibrillar network and its local density proved key in facilitating the understanding of the relationships between self-assembly behavior, local nanostructure and final physical properties of the materials. The understanding of the gelation process of these materials allowed the design of a simple and efficient methodology to prepare gels for cell culture. Tetrapeptide/enzyme solution containing cells could be injected into cell culture plate with subsequent gelation of the materials leading to encapsulation of the cells into a 3D network. This system was evaluated for the 3D cell culture of human dermal fibroblasts (HDF). Microscopy showed that cells were uniformly distributed within the gel matrix. Cell counting and live/dead staining showed proliferation of HDF with limited cell death over 10 days.

Batch sorption experiments were carried out, in a glove box under N2 atmosphere, for analysing the effect of increasing ISA (isosaccharinic acid) concentrations on sorption of Tc(IV) and Pu(IV) onto previously characterised Spanish concrete and mortar used in a radioactive waste repository. Results clearly showed that concentrations of ISA around 10-4–10-3 M are able to decrease the distribution coefficients (Rd) of the tetravalent elements analysed, both on concrete and mortar. The decrease in Rd experimentally observed was approximately 2 orders of magnitude for technetium and between 3 and 5 orders of magnitude for plutonium.

We report the preparation and characterization of binary blend films of poly(vinylidene fluoride) (PVDF) and poly(1- ethyl-3-vinylimidazolium trifluoromethylsulfonylimide) (PVIm+ TFSI-) derived from ionic liquid imidazolium monomers and doped with TFSI- salt. The potential utility of such materials in capacitive electronic devices and in proton exchange membrane fuel cells is of particular interest. Thin PVDF/ PVIm+ TFSI- films were fabricated from solutions of dimethly formamide (DMF) by doctor blading. The nature of the PVDF crystalline polymorph and degree of crystallinity were evaluated as a function of the volume fraction of imidazolium polymer and thermal treatment. The morphology, thermal and mechanical characteristics and crystallinity of PVDF, in semicrystalline blend films was studied by wide angle X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetry, and dynamic mechanical analysis. In these materials, conditions such as choice of solvent, drying conditions, and thermal treatment affect the crystal phase, crystallite size, and degree of crystallinity of PVDF as well as the distribution of the minor component, the vinylimidazolium polymer. The polar beta phase of PVDF crystals dominates in as-cast films, while the non-polar alpha phase is observed after cooling from the melt. PVDF imparts mechanical strength and chemical stability to the composite films, and because of its high crystal melting point (Tm > 160 °C), serves to improve the high temperature stability of resulting films.

Engineering and manufacturing of thick and bio-functional tissue products is one of the big issues in tissue engineering. To produce such tissues, we need some innovative technologies, which enable us to build up thick, three-dimensional structures and to arrange multiple types of cells to make complicated tissue structures. Based on such considerations, we have developed a custom-made inkjet 3D bioprinter, which realized both of direct cell printing and 3D laminating printing with cells and hydrogel. Recently, it has been improved, and here we report recent progresses and our achievements with new version 3D bioprinter.

Image based printing mode and active Z-axis control system were added. As a useful structure, an image of multi-honeycomb pattern was designed in computer and next it was copied and finally in total 100 image data were prepared. Using those digital data, 3D image of thick multi-honeycomb structure was reconstructed in computer, and then, laminating printing was carried out using our new version 3D bioprinter with alginate hydrogel. The new version printer showed good performance of 3D laminating printing and finally complicated 3D multi-honeycomb hydrogel structures could be successfully fabricated. It is indicated that fabrication of cell containing 3D structures based on the computer aided designs is feasible and that such biofabrication technologies must contribute to further innovative advancement of tissue engineering.

Intermetallic titanium aluminides are potential materials for application in high temperature components. In particular, alloys solidifying via the β-phase are of great interest because they possess a significant volume fraction of the disordered body-centered cubic β-phase at elevated temperatures ensuring good processing characteristics during hot-working. Nevertheless, their practical use at temperatures as high as 800°C requires improvements of the oxidation resistance. This paper reports on the fluorine effect on a multi-phase TiAl-alloy in the cast and hot-isostatically pressed condition at 800°C in air. The behavior of the so-called TNM material (Ti-43.5Al-4Nb-1Mo-0.1B, in at %) was compared with that of two other TiAl-alloys which are Nb-free and contain different amounts of Mo (3 and 7 at%, respectively). The oxidation resistance of the fluorine treated samples was significantly improved compared to the untreated samples. After fluorine treatment all alloys exhibit slow alumina kinetics indicating a positive fluorine effect. Results of isothermal and thermocyclic oxidation tests at 800°C in air are presented and discussed in the view of composition and microstructure of the TiAl-alloys investigated, along with the impact of the fluorine effect on the oxidation resistance of these materials.

Modern concepts for biofunctional implants often comprise the controlled release of bioactive compounds to gain specific biofunctionalities. Here, amorphous and semi-crystalline copolyester-based shape-memory polymer (SMP) networks are reported as matrix for pharmaceutical applications. Drug loading of such crosslinked networks by swelling techniques requires tools to determine the actual payload. In this report, the capability of determining loading kinetics by mass increase or changes of drug concentration in the swelling medium is explored for two types of copolyester-based SMP networks differing in their crosslinking chemistry. Nitrofurantoin and ethacridine lactate served as hydrophobic and hydrophilic model drugs. It was found, that the absolute values of the determined payload did not systematically agree with those obtained by the more reliable technique of network cleavage and spectrophotometric quantification. However, the studies indicate that for both types of SMP materials and both drugs, maximum incorporation of the drugs occurred within a few hours. The time until equilibration depended on the network properties.

Light effects on the performance of the a-Si:H PIN photodiode has been studied. The leakage current-voltage and capacitance-voltage curves under the red, green and blue light illuminations were measured. The apparent charge storage density in the negative voltage range was quantified from the capacitance-voltage curve; charges in the positive voltage range were estimated from the leakage current-voltage curve. A comparison of charge storage capacities of diodes with different intrinsic layer thicknesses is also presented. The diode under the long wavelength light illumination condition stored more charges than that under the short wavelength light illumination condition because the former could penetrate the intrinsic a-Si:H layer deeper than the latter could. The leakage current and charge storage capacity of the diode are determined by the generation of electron-hole pairs, the depletion of charges in the intrinsic layer, and the supply of charges from the electrodes. The number of incident photons is critical to the process.

Ribbons of the Ni-44.8wt%Ti shape memory alloy are prepared through the melt spinning technique. The study is focused on investigating the effect of the rapid solidification and grain size at characteristic start martensitic (Ms), final martensitic (Mf), start austenite (As) and final austenite (Af) transformation temperatures. Changes on martensitic transformation temperatures in Ti45Ni55 melt spun ribbons are observed as grain size is reduced. Results of optical microscopy and differential scanning calorimetry (DSC) are used to associate grain size with transformation temperatures.

Kaolin is an important material that is used in industrial applications, including ceramics, paper, paints, fiberglass, inks, pharmaceuticals, and cement. The presence of impurities, particularly iron and titanium bearing materials, imparts color to kaolin. During weathering or hydrothermal alteration, significant levels of iron oxides can be deposited that leave a concentrated kaolinitic clay unusable for industrial application. Therefore, several chemical methods have been applied to kaolin beneficiation in order to reduce these contaminants. Ferric oxide dissolution is of particular interest for producers of industrial minerals such as kaolin. The objective of this work was to examine the kinetics of iron dissolution form low grade kaolin using oxalic acid solutions. The effects of acid concentration and reaction temperature were studied. It was determined that the iron dissolution rate increases with oxalic acid concentration, temperature. Leaching data showed that iron dissolution from low grade kaolin is due to diffusion through the product layer. The activation energy of the process was 46.32 kJ/mol.

Understanding of nickel (Ni) grain size, distribution, and structure are critical parameters in a sputter-deposited Ni catalyst for achieving the desired number of graphene layers [1] grown by atmospheric pressure chemical vapor deposition (APCVD). The size and distribution of grains can be controlled by variations in sputtering parameters, but the final crystal structure and defects are not apparent until after the high temperature annealing. We analyzed the x-ray diffraction patterns in the Ni catalyst to determine effect of thermal annealing on the Ni grain size, orientation, and structural defects. Experiments have shown that in-situ sputter-deposited Ni films at 250 °C are highly oriented in the direction [111] that produced the high yield of graphene films with desired number of layers. Low defect density in a sputtered nickel (Ni) catalyst is a necessary ingredient for achieving precision number of graphene layers. These sputtering parameters can accelerate or postpone the final preferred orientation of the Ni film. A sputter temperature of 250 °C achieved complete transformation from polycrystalline film to the preferred [111] orientated film.

Microwave dielectric heating was utilized to synthesize potential host phases for halide radioisotopes. Synthesis of Pb5(VO4)3I was successfully achieved, without the use of a sealed container, using a modified domestic microwave oven (DMO) operating at 2.45 GHz. Rapid synthesis of Pb5(VO4)3X (X = F, Cl, Br) was also achieved using a commercially available microwave muffle furnace, also operating at 2.45 GHz. The combination of rapid heating rate and inverse temperature profile characteristic of microwave heating was found to promote formation of the target phases whilst retarding the volatilization of the halide species. Pb5(VO4)3I ceramic bodies produced in the DMO exhibited a heterogeneous zoned microstructure, whereas Pb5(VO4)3X phases with X = F, Cl, and Br fabricated in the microwave muffle furnace were dimensionally uniform suggesting this could be a promising route to fabricating single phase, dense halide containing ceramics.

Variation in thermal conductivity of Ag-based composites by introduction of multi-walled carbon nanotubes (MWCNTs) was investigated. The Ag/MWCNT nanocomposite powder was successfully prepared when appropriate surfactants were used via a sonoprocess. The nanocomposite powder was subsequently cured at 280-300 ºC in air. After curing, the thermal conductivity of the nanocomposites was compared with the electronic contribution to thermal conductivity that was estimated from experimental values of the electrical conductivity. The thermal conductivity of Ag/MWCNT nanocomposites was much higher than the electronic contribution. Therefore, the increase in thermal conductivity of the Ag-based nanocomposites is attributed to phonon transfer along the percolation network of MWCNTs.

Thin film bismuth piezoresistors, defined on oxidized silicon wafers, are investigated as a function of their orientation for their eventual integration on micro-electro-mechanical (MEMS) microsensors. Bismuth’s piezoresistance (or elasto-resistance) is experimentally investigated to accurately determine its longitudinal and transverse strain sensitivities. Whisker-shaped resistive elements defined on different orientations (from 0o, the beam’s main strain axis, to 90o, perpendicular to that axis) undergo changes of resistance (ΔR), associated with the induced strains on silicon cantilevers beam’s surface when these are mechanically loaded under pure bending stress conditions. For Bi-resistors, the traditional gage factor concept, (ΔR/Ro)/εl , is found to be equal to +16 and +33, for elements oriented along 0 and 90o, respectively, considerably larger than those for metals or metal alloys. These high sensitivity values and the “unusual” positive, higher value for the 90o (perpendicular) resistors can be of considerable interest for microsensors applications. The results of this study enable us to precisely determine the bismuth’s longitudinal and transverse strain sensitivities that are calculated to be equal to +26 and +40.5 respectively. This experimental study is extended to explore the Bi-films’ response to bi-axial strain fields.

Vaterite is one of the thermodynamically less stable polymorphs of calcium carbonate. Under ambient conditions it transforms into calcite, the most stable form of calcium carbonate. Organisms are able to stabilize minerals such as vaterite by means of organic molecules. The exact mechanisms how biomineralization proteins interact with metastable mineral phases are, however, less well understood. Many in vitro studies were performed using calcite as a model system. A deeper understanding of the interaction of organic molecules with metastable mineral phases would make them useful as a tool to control mineralization processes in vitro. In this study, we report on the co-precipitation of a natively soluble histidine-tagged GFP (green fluorecent protein) with a metastable vaterite phase and the subsequent insolubility of the fluorescent organic matrix in a 30μl calcium carbonate precipitation assay. The intrinsic fluorescence of GFP is conserved during the interaction with the mineral phase, indicating proper folding even in the insoluble state. This experiment can be extended to obtain deeper insights into some mechanistic models of biomineralization proteins by tracking native and modified GFP proteins microscopically during various stages of mineral precipitation and dissolution.

A pulsed laser deposition system was employed to fabricate thin films of Li7La3Zr2O12 solid electrolyte. The deposition process was carried out at room-temperature, resulting in amorphous films. These as-deposited films had a large optical band gap of 5.13 eV, and exhibited a lithium-ion conductivity of 3.35×10-7 S/cm. The films were then annealed, and the effect of annealing on the optical and electrical properties of the films was examined. After annealing at 1000 °C, the films were found to be cubic with a narrower band gap of 3.64 eV. In addition, these annealed films showed an inferior ionic conductivity than the as-deposited ones.

The elastic properties of chalcogenide materials used for phase change applications in rewritable optical media (such as CD-RW, DVD-RW, etc) are still poorly characterized and the previously published experimental and theoretical values show large discrepancies. In this manuscript, we review these results and carry out a careful analysis of the elastic properties of a model system, crystalline Ge1Sb2Te4, using density functional theory and elastic anisotropy considerations. We show that Ge1Sb2Te4 exhibits significant anisotropy in its elastic properties.

Wireless power transfer is experimentally demonstrated by transmission between an AC power transmitter and receiver, both realised using thin film technology. The transmitter and receiver thin film coils are chosen to be identical in order to promote resonant coupling. Planar spiral coils are used because of the ease of fabrication and to reduce the metal layer thickness. The energy transfer efficiency as a function of transfer distance is analysed along with a comparison between the theoretical and the experimental results.