Surface structures and osteoblast response of hydrothermally produced CaTiO3 thin film on Ti-13Nb-13Zr alloy

This study investigated the surface characteristics and in vitro biocompatibility of a titanium (Ti) oxide layer incorporating calcium ions (Ca) obtained by hydrothermal treatment with or without post heat-treatment in the Ti-13Nb-13Zr alloy. The surface characteristics were evaluated by scanning electron microscopy, thin-film X-ray diffractometry, X-ray photoelectron spectroscopy, atomic force microscopy and contact angle measurements. In vitro biocompatibility of the Ca-containing surfaces was assessed in comparison with untreated surfaces using a pre-osteoblast cell line. Hydrothermal treatment produced a crystalline CaTiO₃ layer. Post heat-treatment at 400 °C for 2 h in air significantly decreased water contact angles in the CaTiO₃ layer (p < 0.001). The Ca-incorporated alloy surfaces displayed markedly increased cell viability and ALP activity compared with untreated surfaces (p < 0.001), and also an upregulated expression of various integrin genes (α1, α2, α5, αv, β1 and β3) at an early incubation time-point. Post heat-treatment further increased attachment and ALP activity in cells grown on Ca-incorporated Ti-13Nb-13Zr alloy surfaces. The results indicate that the Ca-incorporated oxide layer produced by hydrothermal treatment and a simple post heat-treatment may be effective in improving bone healing in Ti-13Nb-13Zr alloy implants by enhancing the viability and differentiation of osteoblastic cells.     

Perturbation theory analysis for electronic response of DNA base pairs

The electronic responses of duplex B-DNA sequences are investigated using perturbation theory analyses. The electronic polarizability and effective mass are computed for base pair doublets and triplets and the electronic structures are calculated according to density functional theory. High polarizability and a light effective mass are obtained in a sequence such as 5′-GGG-3′. The results indicate that the concentration of GC base pairs causes a high response of the electronic states, and molecular orbitals that are very responsive to the electric field tend to be reactive with other orbitals or conducting hole carriers. Furthermore, the interaction between the electronic states and a positively charged wavepacket is discussed, assuming hole injection in the DNA sequences. The sequence of 5′-GGG-3′ responds sensitively to the external hole approach, which is presumably injected to a guanine site.     

Optical properties of AgI/Ag infrared hollow fiber in the visible wavelength region

We report on AgI/Ag infrared hollow fiber with low-loss in visible region. Improved methods of silver plating and iodination were proposed to fabricate the hollow fiber. The surface roughness of the silver layer and the silver iodide layer was reduced by the pretreatment with an SnCl2 solution and low iodination temperature. Losses for the Er:YAG and green laser light were 0.4 and 7dB/m. The loss property of green laser beam was low to deliver a pilot beam for the invisible infrared laser light. Owing to the smooth and uniform AgI film, the loss spectrum of the hollow fiber showed clear interference peaks in the visible region. An empirical formula for AgI material dispersion was derived, which is of special importance for the design of high-performance AgI/Ag hollow fiber.     

One‐Handed Helical Screw Direction of Homopeptide Foldamer Exclusively Induced by Cyclic α‐Amino Acid Side‐Chain Chiral Centers

Chiral cyclic α,α‐disubstituted amino acids, (3S,4S)‐ and (3R,4R)‐1‐amino‐3,4‐(dialkoxy)cyclopentanecarboxylic acids ((S,S)‐ and (R,R)‐Ac₅c^dOR; R: methyl, methoxymethyl), were synthesized from dimethyl L ‐(+)‐ or D ‐(?)‐tartrate, and their homochiral homoligomers were prepared by solution‐phase methods. The preferred secondary structure of the (S,S)‐Ac₅c^dOMe hexapeptide was a left‐handed (M) 3₁₀ helix, whereas those of the (S,S)‐Ac₅c^dOMe octa‐ and decapeptides were left‐handed (M) α helices, both in solution and in the crystal state. The octa‐ and decapeptides can be well dissolved in pure water and are more α helical in water than in 2,2,2‐trifluoroethanol solution. The left‐handed (M) helices of the (S,S)‐Ac₅c^dOMe homochiral homopeptides were exclusively controlled by the side‐chain chiral centers, because the cyclic amino acid (S,S)‐Ac₅c^dOMe does not have an α‐carbon chiral center but has side‐chain γ‐carbon chiral centers.     

Rugged distal tips for CO2 laser medicine

Low-loss and rugged distal tips for CO₂ laser have been proposed and fabricated based on a commercially available stainless steel (St) pipe. A method of smoothening the inner surface of the St pipe with a rough inner surface is put forward. Fabrication parameters, transmission properties, and mechanical strength of the cyclic olefin polymer-coated silver hollow St distal tip are experimentally discussed.     

Well‐Defined Iron Complexes as Efficient Catalysts for “Green” Atom‐Transfer Radical Polymerization of Styrene,Methyl Methacrylate,and Butyl Acrylate with Low Catalyst Loadings and Catalyst Recycling

Environmentally friendly iron(II) catalysts for atom‐transfer radical polymerization (ATRP) were synthesized by careful selection of the nitrogen substituents of N,N,N‐trialkylated‐1,4,9‐triazacyclononane (R₃TACN) ligands. Two types of structures were confirmed by crystallography: “[(R₃TACN)FeX₂]” complexes with relatively small R groups have ionic and dinuclear structures including a [(R₃TACN)Fe(μ‐X)₃Fe(R₃TACN)]⁺ moiety, whereas those with more bulky R groups are neutral and mononuclear. The twelve [(R₃TACN)FeX₂]_n complexes that were synthesized were subjected to bulk ATRP of styrene, methyl methacrylate (MMA), and butyl acrylate (BA). Among the iron complexes examined, [{(cyclopentyl)₃TACN}FeBr₂] ( 4 b ) was the best catalyst for the well‐controlled ATRP of all three monomers. This species allowed easy catalyst separation and recycling, a lowering of the catalyst concentration needed for the reaction, and the absence of additional reducing reagents. The lowest catalyst loading was accomplished in the ATRP of MMA with 4 b (59 ppm of Fe based on the charged monomer). Catalyst recycling in ATRP with low catalyst loadings was also successful. The ATRP of styrene with 4 b (117 ppm Fe atom) was followed by precipitation from methanol to give polystyrene that contained residual iron below the calculated detection limit (0.28 ppm). Mechanisms that involve equilibria between the multinuclear and mononuclear species were also examined.     

Solid‐Phase Combinatorial Synthesis and Biological Evaluation of Destruxin E Analogues

The solid‐phase combinatorial synthesis of cyclodepsipeptide destruxin E has been demonstrated. The combinatorial synthesis of cyclization precursors 8 was achieved by using a split and pool method on SynPhase Lanterns. The products were successfully macrolactonized in parallel in the solution phase by using 2‐methyl‐6‐nitrobenzoic anhydride and 4‐(dimethylamino)pyridine N‐oxide to afford macrolactones 9 , and the subsequent formation of an epoxide in the side chain gave 18 member destruxin E analogues 6 . Biological evaluation of analogues 6 indicated that the N‐MeAla residue was crucial to the induction of morphological changes in osteoclast‐like multinuclear cells (OCLs). Based on structure–activity relationships, azido‐containing analogues 15 were then designed for use as a molecular probe. The synthesis and biological evaluation of analogues 15 revealed that 15 b , in which the Ile residue was replaced with a Lys(N₃) residue, induced morphological changes in OCLs at a sufficient concentration, and modification around the Ile residue would be tolerated for attachment of a chemical tag toward the target identification of destruxin E ( 1 ).