Hierarchically branched titania nanotubes with tailored diameters and branch numbers

Over the past decade, electrochemical anodization of self-organized TiO(2) nanotubes has been studied intensively with the main focus being on uniform diameters along the TiO(2) nanotube depth direction. In the present work, hierarchically branched TiO(2) nanotubes with tailored diameters and branch numbers are successfully achieved by adjusting the anodization voltage. Reducing the applied voltage by a factor of 1/√n causes a one trunk nanotube to diverge into n-branched TiO(2) nanotubes, whose diameters are 1/√n of the trunk nanotube diameter (n is an integer). Multiple layers of branched TiO(2) nanotubes are also obtained by further dividing the branched nanotubes when the applied voltage is further reduced step-by-step with a 1/√n factor. Enlargement and termination of TiO(2) nanotubes occur when the anodization voltage increases by √n times. Alternating increase and decrease in the applied voltage lead to a more sophisticated hierarchical structure of TiO(2) nanotubes. The fundamental understanding of these processes is discussed.     

Effect of Polymer Degree of Conversion on Streptococcus mutans Biofilms

Biofilm–material interactions are increasingly recognized as critical to success of some materials/devices and failure of others. We use a model system of dental monomers, salivary pellicles, and oral biofilms to demonstrate for the first time that degree of conversion of cross‐linked dimethacrylate polymers alters biofilm metabolic activity. This response is due primarily to leachable release (not surface chemistry) and is complex, with no changes in some biofilm measurements (i.e., biomass), and time‐ and leachable‐dependent responses in others (i.e., metabolic activity). These results highlight the need for considering biofilm‐material interactions when designing/evaluating new materials.

     

Complex inorganic/organic core-shell architectures via an inverse emulsion process

The preparation of complex inorganic/organic core-shell particles and their in situ hydrophobization via an inverse emulsion technique is described here. Typically, aqueous solutions of precursor salts are dispersed with the help of statistical copolymers in an organic phase and subsequently polymer-stabilized nanoparticles precipitate at room temperature (e.g., barium- or strontium-based perovskite nanoparticles). By this technique, core-multiple-shell ZnO–silica–polymer nanoparticles may also be obtained, whereby the polymer matrix is protected against the photocatalytically active ZnO by the silica shell. The particles are characterized by X-ray, transmission electron microscopy, and dynamic light scattering. In this approach, amphiphilic statistical copolymers act not only as stabilizers for inverse emulsions, but they also hydrophobize the remaining complex inorganic particles shelled on the surface after the precipitation. The preparation of hybrid nanoparticles is performed by a one-pot procedure, which makes this process attractive for industrial applications.     

Zeros of linear combinations of Laguerre polynomials from different sequences

We study interlacing properties of the zeros of two types of linear combinations of Laguerre polynomials with different parameters, namely and . Proofs and numerical counterexamples are given in situations where the zeros of R_n, and S_n, respectively, interlace (or do not in general) with the zeros of , , k=n or n−1. The results we prove hold for continuous, as well as integral, shifts of the parameter α.     

The electronic and chemical structure of the a-B(3)CO(0.5):H(y)-to-metal interface from photoemission spectroscopy: implications for Schottky barrier heights

The electronic and chemical structure of the metal-to-semiconductor interface was studied by photoemission spectroscopy for evaporated Cr, Ti, Al and Cu overlayers on sputter-cleaned as-deposited and thermally treated thin films of amorphous hydrogenated boron carbide (a-B(x)C:H(y)) grown by plasma-enhanced chemical vapor deposition. The films were found to contain ～10% oxygen in the bulk and to have approximate bulk stoichiometries of a-B(3)CO(0.5):H(y). Measured work functions of 4.7/4.5?eV and valence band maxima to Fermi level energy gaps of 0.80/0.66?eV for the films (as-deposited/thermally treated) led to predicted Schottky barrier heights of 1.0/0.7?eV for Cr, 1.2/0.9?eV for Ti, 1.2/0.9?eV for Al, and 0.9/0.6?eV for Cu. The Cr interface was found to contain a thick partial metal oxide layer, dominated by the wide-bandgap semiconductor Cr(2)O(3), expected to lead to an increased Schottky barrier at the junction and the formation of a space-charge region in the a-B(3)CO(0.5):H (y) layer. Analysis of the Ti interface revealed a thick layer of metal oxide, comprising metallic TiO and Ti (2)O (3), expected to decrease the barrier height. A thinner, insulating Al(2)O(3) layer was observed at the Al-to-a-B(3)CO(0.5):H(y) interface, expected to lead to tunnel junction behavior. Finally, no metal oxides or other new chemical species were evident at the Cu-to-a-B(3)CO(0.5):H(y) interface in either the core level or valence band photoemission spectra, wherein characteristic metallic Cu features were observed at very thin overlayer coverages. These results highlight the importance of thin-film bulk oxygen content on the metal-to-semiconductor junction character as well as the use of Cu as a potential Ohmic contact material for amorphous hydrogenated boron carbide semiconductor devices such as high-efficiency direct-conversion solid-state neutron detectors.     

Towards Non-Targeted Screening of Lipid Biomarkers for Improved Equine Anti-Doping

The current approach to equine anti-doping is focused on the targeted detection of prohibited substances. However, as new substances are rapidly being developed, the need for complimentary methods for monitoring is crucial to ensure the integrity of the racing industry is upheld. Lipidomics is a growing field involved in the characterisation of lipids, their function and metabolism in a biological system. Different lipids have various biological effects throughout the equine system including platelet aggregation and inflammation. A certain class of lipids that are being reviewed are the eicosanoids (inflammatory markers). The use of eicosanoids as a complementary method for monitoring has become increasingly popular with various studies completed to highlight their potential. Studies including various corticosteroids, non-steroidal anti-inflammatories and cannabidiol have been reviewed to highlight the progress lipidomics has had in contributing to the equine anti-doping industry. This review has explored the techniques used to prepare and analyse samples for lipidomic investigations in addition to the statistical analysis and potential for lipidomics to be used for a longitudinal assessment in the equine anti-doping industry.     

The effect of branching on chain diffusion in ultralong N-alkane crystals observed by 13C NMR

¹³C NMR progressive saturation measurements are used to investigate solid state chain diffusion in semicrystalline alkanes. Monodisperse, ultralong n-alkanes, of 198 and 191 carbon atoms in length, are characterized and prepared in such a way that they comprise crystals containing chains which are exclusively of once-folded conformation. This preparation is confirmed with DSC and SAXS. The progressive saturation experiments show that the longitudinal relaxation of magnetisation is consistent with a solid state chain diffusion process. Reptation and one-dimensional diffusion models are demonstrated to satisfactorily represent the data. The addition of branches to the alkane chains is shown to result in a decrease in the diffusion coefficient. The obtained diffusion coefficients range from 0.0918 nm²s⁻¹ for the linear chain to 0.016 nm²_s⁻¹ for a chain with a branch 4 carbons in length. These diffusion coefficients are consistent with those previously obtained for polyethylenes.