Oligonucleotides Containing Phenoxazine Artificial Nucleobases: Triplex-Forming Abilities and Fluorescence Properties

1,3-Diaza-2-oxophenoxazine (“phenoxazine”), a tricyclic cytosine analogue, can strongly bind to guanine moieties and improve π–π stacking effects with adjacent bases in a duplex. Phenoxazine has been widely used for improving duplex-forming abilities. In this study, we have investigated whether phenoxazine and its analogue, 1,3,9-triaza-2-oxophenoxazine (9-TAP), could improve triplex-forming abilities. A triplex-forming oligonucleotide (TFO) incorporating a phenoxazine component was found to show considerably decreased binding affinity with homopurine/homopyrimidine double-stranded DNA, so the phenoxazine system was considered not to function as either a protonated cytosine or thymine analogue. Alternatively, a 9-TAP-containing artificial nucleobase developed by us earlier as a new phenoxazine analogue functioned as a thymine analogue with respect to AT base pairs in a parallel triplex DNA motif. The fluorescence of the 9-TAP moiety was maintained even in triplex (9-TAP:AT) formation, so 9-TAP might be useful as an imaging tool for various oligonucleotide nanotechnologies requiring triplex formation.     

Practical model for low electric field direct-tunnelling currentcharacteristics in nanometer-thick oxide films

A practical model for direct-tunnelling characteristics at low electric fields in nanometre-thick SiO₂ films is proposed. The model allows for the effective increase in the tunnelling barrier width with a quantum-mechanical consideration of the electron density near the Si-SiO₂ interface. The simulation results coincide well with experimental results     

A new BEDT-TTF-based organic metal with an anionic weak acceptor 2-sulfo-1,4-benzoquinone

An anionic weak acceptor, 2-sulfo-1,4-benzoquinone, has provided a new BEDT-TTF (bis(ethylenedithio)tetrathiafulvalene) salt (BEDT-TTF)₂(2-sulfo-1,4-benzoquinone)·H₂O. Single crystal X-ray analysis indicates that the unit cell has two crystallographically independent donor layers, one of which has a β″-type packing motif and the other being disordered. Population analysis and SQUID magnetometry suggests that non-β″-layer has an α?-type packing motif. The dual-layered salt shows metallic behavior with a metal–insulator transition at 90 K.     

New radical salts based on TEMPO-substituted 2,4,6-triphenylpyridinium and transition metal complexes

Series of radical salts derived from a 2,4,6-triphenylpyridinium (TPP) carrying TEMPO-substituent and transition metal complexes were prepared by the anion exchange of the TPP–TEMPO tetrafluoroborate with [n-Bu₄N][Ni(dmit)₂], [n-Bu₄N]₂[Pd(dmit)₂], [n-Bu₄N]₂[Pt(dmit)₂], [n-Bu₄N][Ni(mnt)₂], or [n-Bu₄N]₂[Ni(mnt)₂] to give crystals with different structural features. While weak antiferromagnetic interactions of the Curie–Weiss behavior of S = 1/2 spin are predominantly observed in the salts of Pd(dmit)₂, Pt(dmit)₂ and Ni(mnt)₂, the magnetic behavior of 1:1 Ni(dmit)₂ salt can be explained by the additional contribution from the spins on Ni(dmit)₂ anions (χ − χ_TEMPO), obeying the 2D Heisenberg model. A couple of the oxidized salts, [TPP][Ni(dmit)₂] as well as [TPP]₂[Pd(dmit)₂], exhibit semi-conducting properties with relatively high room temperature conductivities.     

Detecting innovative topics based on user-interest ontology

In this paper, we detect “innovative topics”, those that are new and hopefully interesting to the user. We try to expand user interests significantly by letting the user browse those topics.We first generate user-interest ontologies that allow user profiles to be constructed as a hierarchy of classes where a user interest weight is assigned to each class and instance. Next, we measure the similarity between user interests by using interest weights on their user-interest ontologies and generate user group G_U that has high similarity to user u. The innovative topics for u are then detected by determining a suitable size of G_U and analyzing the ontologies in G_U.     

Structural Evolution of Highly Active Ir-Based Catalysts for the Selective Reduction of NO with Reductants in Oxidizing Conditions

NO _x reduction over Ir-based catalysts in the presence of excess oxygen with hydrocarbon as a reductant was investigated in the focus on observing microstructure of Ir particle supported on various carriers and structural evolution of highly active Ir-based catalysts in the NO _x reduction. Characterization of Ir-based catalysts using SEM, TEM, XRD, CO chemisorption and XPS, and reaction studies on various Ir-based catalysts have proved that the formation of relatively large Ir metal particle with 40–60 nm of nanocrystal size carried on inert supports has been a prerequisite for the evolution of high activities in the NO _x reduction rather than the formation of Ir metal state on the catalyst. Furthermore, in inert gas conditions in a high temperature range of 850–950°C, Ir metal was easily formed by using the support such as TiO₂ and ZrO₂ that drastically decreased its specific surface area in the temperature range.     

Preparation, surface-active properties, and antimicrobial activities of bis(alkylammonium) dichlorides having a butenylen or a butynylene spacer

A series of new cationic gemini surfactants, bis(alkylammonium) dichlorides having a butenylene or a butynylene spacer, were prepared almost quantitatively by the reaction of a long-chain alkyldimethylamine with a highly reactive allylic or propargylic dichloride, and their surface-active properties were measured. All of them showed good water solubility and quite low critical micelle concentrations, which were more than one order of magnitude lower than those of the corresponding mono(alkylammonium) salts. They also showed quite high foaming ability and foam stability when they have an appropriate hydrophile-lipophile balance. Many of them showed almost the same antimicrobial activities against the eumycetes Aspergillus sp. and Candida albicans as commercial germicides such as benzalkonium chloride and chlorhexidine gluconate.