RESUMEN
A resin monomer-soluble polyrotaxane (PRX) crosslinker with cleavable end groups was synthesized to develop degradable photosetting composite resins. The PRX containing 50 α-cyclodextrins (α-CDs) with disulfide end groups was initially modified with n-butylamine to obtain a resin monomer-soluble PRX. The PRX containing 13 n-butyl groups per α-CD molecule was completely soluble in conventional resin monomers such as 2-hydroxyethyl methacrylate (HEMA) and urethane dimethacrylate (UDMA). The synthesized n-butyl-containing PRX was further modified with 2-aminoethyl methacrylate to provide crosslinkable acrylic groups onto PRX. The prepared resin monomer-soluble PRX crosslinker was successfully polymerized with a mixture of HEMA and UDMA to provide photosetting plastic. It was confirmed that the Vickers hardness of the prepared plastic was greatly decreased after treatment with dithiothreitol. This indicates that the resin monomer-soluble PRX crosslinker can be applied to design degradable photosetting plastics potentially used in the industrial or biomedical field.
RESUMEN
We grew graphene by thermal decomposition of B(4)C and investigated its features by high-resolution transmission electron microscope observations. At temperatures higher than 1600 °C in a vacuum, B(4)C decomposes and graphene forms epitaxially on its surface. The number and the morphology of the graphene layers depend on the surface orientation. An electron diffraction technique revealed the presence of a superstructure with a two-times larger unit cell, which is consistent with the structure of BC(3). We have directly confirmed boron in the graphene layers by electron energy loss spectroscopy measurements and boron-mapping experiments.
RESUMEN
A unique tactic for the separation of single-base sequential isomers of oligomeric single-stranded DNA by a CE separation system employing the specific interaction of metal ion with nucleotide was demonstrated, enabling the separation of the mixture of a 12-mer oligonucleotide and its single-base mutants, as well as their positional isomers.
