Purification and uniqueness of quantum Gibbs states

We give a new condition for uniqueness of Gibbs states of quantum spin models on lattices.Research fellow of Canon Foundation in Europe, on leave from Tokyo Metropolitan University, Hachioji, 192-03 Japan     

Translational Symmetry Breaking and Soliton Sectors for Massive Quantum Spin Models in 1 + 1 Dimensions

We consider the classification of pure infinite volume ground states and that of soliton sectors for 1+1 dimensional massive quantum spin models. We obtain a proof that non-translationally invariant ground state cannot exist for a class of translationally invariant Hamiltonians including the spin 1 AKLT (Affleck Kennedy Lieb Tasaki) antiferromagnetic spin model. We also obtain a complete classification of soliton sectors (up to unitary equivalence) for certain massive models (e.g. ferromagnetic XXZ models). Received: 13 January 1997 / Accepted: 11 March 1997     

7,10,14-Tri-t-butyl-3-hydroxy-1,8-bisdehydro[14]annulene

Tri-t-butyl-(β-methoxyethoxy)methoxybisdehydro[14]annulene has been prepared. Cleavage of the ether linkage to give hydroxyannulene was unsuccessful. Treatment of the methoxy analogue with iodotrimethylsilane yielded iodoketone, which gave anion of hydroxyannulene by the reaction with base. Formation of hydroxyannulene could be confirmed by NMR spectroscopy and reconversion of the anion into the methoxyannulene.     

Effects of frequency/polarization allocations and the zero-dispersion frequency on FDM lightwave transmission systems

In long-haul frequency-division-multiplexing lightwave transmission systems, transmission characteristics are degraded by four-wave mixing (FWM) generated in optical fibers. To overcome this problem, several FWM suppression techniques have been reported. In this paper, dependence of FWM noises on frequency allocations, polarization allocations, and the zero-dispersion frequency is investigated. It is revealed that FWM noises are drastically decreased in frequency allocations such as equally spaced, repeated unequally spaced (RUS), equally spaced RUS, and unequally spaced RUS allocations by arranging polarization allocations of the channels with an increase in a separation between the channel frequencies and the zero-dispersion frequency.     

Dominant parameters for maximum velocity induced by body-force models for plasma actuators

This study investigates the relationship between body-force fields and maximum velocity induced in quiescent air for development of a simple body-force model of a plasma actuator. Numerical simulations are conducted with the body force near a wall. The spatial distribution and temporal variation of the body force are a Gaussian distribution and steady actuation, respectively. The dimensional analysis is performed to derive a reference velocity and Reynolds number based on the body-force distribution. It is found that the derived Reynolds number correlates well with the nondimensional maximum velocity induced in quiescent conditions when the center of the Gaussian distribution is fixed at the wall. Additionally, two flow regimes are identified in terms of the Reynolds number. Considering the variation of the center of gravity of force fields, another Reynolds number is defined by introducing a new reference length. The nondimensional maximum velocity is found to be scaled with the latter Reynolds number, i.e., the maximum induced velocity in quiescent conditions is determined from three key parameters of the force field: the total induced momentum per unit time, the height of the center of gravity, and the standard deviation from it. This scaling turns out to be applicable to existing body-force models of the plasma actuator, despite the force distributions different from the Gaussian distribution. Comparisons of velocity profiles with experimental data validate the results and show that the flow induced by a plasma actuator can be simulated with simple force distributions by adjustment of the key body-force parameters.     

High‐Yield Excited Triplet States in Pentacene Self‐Assembled Monolayers on Gold Nanoparticles through Singlet Exciton Fission

One of the major drawbacks of organic‐dye‐modified self‐assembled monolayers on metal nanoparticles when employed for efficient use of light energy is the fact that singlet excited states on dye molecules can be easily deactivated by means of energy transfer to the metal surface. In this study, a series of 6,13‐bis(triisopropylsilylethynyl)pentacene–alkanethiolate monolayer protected gold nanoparticles with different particle sizes and alkane chain lengths were successfully synthesized and were employed for the efficient generation of excited triplet states of the pentacene derivatives by singlet fission. Time‐resolved transient absorption measurements revealed the formation of excited triplet states in high yield (172±26 %) by suppressing energy transfer to the gold surface.     

Direct labeling of 5-methylcytosine and its applications

Cytosine methylation is one of the most important epigenetic events, and much effort has been directed to develop a simple reaction for methylcytosine detection. In this paper, we describe the design of tag-attachable ligands for direct methylcytosine labeling and their application to fluorescent and electrochemical assays. The effect of the location of bipyridine substituents on the efficiency of osmium complexation at methylcytosine was initially investigated. As a result, a bipyridine derivative with a substituent at the C4 position showed efficient complexation at the methylcytosine residue of single-stranded DNA in a reaction mixture containing potassium osmate and potassium hexacyanoferrate(III). On the basis of this result, a bipyridine derivative with a tag-attachable amino linker at the C4 position was synthesized. The efficiency of metal complex formation in the presence of the osmate and the synthetic ligand was clearly changed by the presence/absence of a methyl group at the C5 position of cytosine. The succinimidyl esters of functional labeling units were then attached to the bipyridine ligand fixed on the methylcytosine. These labels attached to methylcytosine enabled us to detect the target methylcytosine in DNA both fluorometrically and electrochemically. For example, we were able to fluorometrically obtain information on the methylation status at a specific site by means of fluorescence resonance energy transfer from a hybridized fluorescent DNA probe to a fluorescent label on methylcytosine. In addition, by the combination of electrochemically labeled methylcytosine and an electrode modified by probe DNAs, a methylcytosine-selective characteristic current signal was observed. This direct labeling of methylcytosine is a conceptually new methylation detection assay with many merits different from conventional assays.