Surface‐Modifiable Free‐Floating Films Formed by Multiway Connection of Collagen‐Like Triple‐Helical Peptides

Square‐millimeter‐sized free‐floating translucent films are formed in physiological buffer by multiway connections between biotinylated collagen‐like triple‐helical peptides and avidin. Although the compositions of the films are almost constant, regardless of the ratios of the components loaded, their thicknesses can be controlled by the concentrations of the components. The film surfaces can be further modified by taking advantage of exposed biotin (or avidin) functionalities. The self‐assembled films could serve as novel materials in biomedical and biosensing applications.     

Comparability of data for natural radionuclides in marine sediment obtained by different analytical techniques

In the paper are presented results of potassium, uranium, thorium and radium measurements performed on the natural marine sediment sample SD-N-1/2 in the framework of the IAEA-organized worldwide intercomparison exercise. Analytical methods applied in this exercise were evaluated for performance and significance of the observed discrepancies are discussed in the light of statistical and operative criteria. Possible sources of error have been identified in alpha and gamma spectrometric measurements and suggestions are given about how to avoid them. Well characterized reference materials based on natural matrices have been shown helpful in achieving better data comparability in low level measurements of environmental radioactivity.     

Fabrication and properties of fullerodendron thin films

Thin films of fullerodendron (C(60)(Gn-COOMe) (n = 0.5, 1.5, 2.5)), which was synthesized from fullerene and anthracenyl poly(amido amine) dendron with methyl ester terminals and different generations (G), were fabricated by the Langmuir-Blodgett (LB) and adsorption techniques. It was characterized by X-ray reflectometry that the LB films possessed well-ordered structure, although the adsorption method led to random orientation of molecules. As to C(60)(G0.5-COOMe) and C(60)(G1.5-COOMe), the LB films took a four-layer structure consisting of a double layer of molecules, and fullerene moieties exist in the interior of the LB films. On the other hand, C(60)(G2.5-COOMe) led to a two-layer structure in which the fullerene moieties were at the air side and the dendron moieties were at the substrate side. With increasing generation of dendron, the monolayer formation ability at the air/water interface as amphiphilic molecule strengthens and the amphiphilic property becomes superior to the fullerene-fullerene attractive interaction that prevents the monolayer formation. Furthermore, in the case of C(60)(G0.5-COOMe) and C(60)(G1.5-COOMe), the reduction peak in cyclic voltammetry of the LB film remained even after UV light irradiation. On the contrary, the peak of the C(60)(G2.5-COOMe) LB film disappeared, indicating that molecular arrangement in the films affects electrochemical properties.     

Synthesis of hexahydropyrrolo[2,3-b]indole alkaloids based on the aza-Pauson-Khand-type reaction of alkynecarbodiimides

Upon treatment with 30 mol % of Co2(CO)(8) and 30 mol % of TMTU in toluene at 70 degrees C, benzene-bridged alkynecarbodiimides efficiently underwent a ring-closing reaction to give the pyrrolo[2,3-b]indol-2-ones in good yields. These conditions could nearly suppress the formation of the urea derivatives, which were consistently observed when 10 mol % of Co2(CO)(8) and 60 mol % of TMTU in benzene were used. The synthesis of the eight hexahydropyrrolo[2,3-b]indole alkaloids was accomplished from the resulting pyrrolo[2,3-b]indol-2-ones via the introduction of an angular substituent at the C(3a)-position by treatment with NaBH(4)/alkyl bromide as the crucial step.     

Photoreaction of 1H‐azepine‐2,7‐dione in alkaline solution

Photolysis of 1H‐azepine‐2,7‐dione 2 proceeded with alkali as in the photoreaction of N‐alkylimide to give 7‐hydroxy‐1H‐azepine‐2‐one 13 .     

Preparation of SnO2 Monolithic Gel by Sol-Gel Method

The effects of aging of a wet gel at room temperature and a use of a drying control chemical additive (DCCA) were investigated on the prevention of cracking of the gel during drying. N,N-Dimethylformamide (DMF) having low surface tension was used as a DCCA in this study. Before drying, the aged wet gel was immersed in DMF for several days to replace the pore liquid in the wet gel with DMF.The longer the aging and DMF immersing times became, a fewer cracks generated during drying. Especially, the immersion in DMF for over 8 days made it possible to obtain the SnO₂ gel monolith without cracking from the wet gel aged for short time (1 day). However, the wet gel aged for long time without immersing in DMF could not be dried without cracking. Therefore, the replacement of the pore liquid in the wet gel with DMF having low surface tension is thought to be more effective on avoiding a crack generation than aging. From a pore size distribution measurement by N₂ gas adsorption, it was found that the pore size and the breadth of the pore size distribution of the dried gel became larger and narrower respectively with increasing DMF immersing time. DMF is thought to be capable of forming strong hydrogen bonding to hydroxyl groups remaining on the surface of the wet gel and providing a shielding cage around the reactants (Sn–OH), thus further condensation reaction is probably suppressed. Consequently, a large pore distribution is developed in the gel, which reduces the magnitude of capillary stress induced during drying.     

Hydrogen-induced states in VHx and VDx observed by soft X-ray emission spectroscopy

From measurements of soft X-ray emission spectra (V-L₃) of VH_x and VD_x, a gradual change of d-band of V metal with addition of H(D), and an appearance of H(D)-induced states immediately below the d-band, are clearly demonstrated. The states, located at 7 eV below the Fermi energy for all compositions, are interpreted as being bonding states formed by H(D)-1s and V-3d orbitals. No isotope effects were detected within the accuracy of the experiment.     

Anomalous diffusion of hydrogen in β-VHx: Pulsed-NMR experiments on H1

Diffusion of hydrogen atoms in β-VH_x has been studied by means of a pulsed-NMR technique. A large temperature dependence of the activation energy towards the phase transition temperature βα has been noted, and is interpreted in terms of a saddle point energy and the energy of stabilization of c-octahedral sites relative to other sites.     

A stereoselective synthesis of (±)-homochelidonine

(±)-Homochelidonine (1) was stereoselectively synthesized from berberine (3) through C₆-N bond cleavage, followed by recyclization between C-6 and C-13 position of the latter according to a biogenetic route.