Tropical representation of Weyl groups associated with certain rational varieties

Starting from certain rational varieties blown-up from N(P¹), we construct a tropical, i.e., subtraction-free birational, representation of Weyl groups as a group of pseudo-isomorphisms of the varieties. We develop an algebro-geometric framework of τ-functions as defining functions of exceptional divisors on the varieties. In the case where the corresponding root system is of affine type, our construction yields a class of (higher order) q-difference Painlevé equations and its algebraic degree grows quadratically.     

Toda equation and special polynomials associated with the Garnier system

We prove that a certain sequence of τ-functions of the Garnier system satisfies Toda equation. We construct algebraic solutions of the system by the use of Toda equation; then show that the associated τ-functions are expressed in terms of the universal character which is a generalization of Schur polynomial attached to a pair of partitions.     

Fluorescence Energy Transfer Study of Interstrand DNA Cross-linking Caused by Rigid Bisintercalator

The intermolecular cross-linking of DNA with a rigid bisintercalator, 1,4-bis(( N -methylquinolinium-4-yl)vinyl)benzene (pMQVB) has been studied using fluorescence resonance energy transfer (FRET), fluorescence anisotropy measurements, and dynamic fluorescence microscopy. Short DNA duplexes, single-labeled with fluorescein (donor) and x-rhodamine (acceptor), were used as energy transfer partners. Due to the quenching effect of pMQVB on the emission of both fluorescein and x-rhodamine, the energy transfer was monitored using the corrected Stern-Volmer plots. The cross-linking ability of pMQVB depended on the ligand structure; the planar E , E isomer cross-linked DNA contrary to the non-planar E , Z isomer. Dynamic fluorescence microscopy observation also demonstrated the ability of pMQVB to cross-link large T4 DNA molecules.     

Photochemistry and photocuring properties of thiol‐substituted α‐aminoalkylphenone as radical photoinitiator

Thiol‐substituted α‐aminoalkylphenone was newly developed as a radical photoinitiator. Introduction of the thiol group drastically improved photosensitivity in an alkaline developable resist formulation composed of a prepolymer and a multifunctional acrylate monomer. The improvement in the photocuring speed was explained by a mechanism based on chain transfer reaction of the thiol group. Time‐resolved electron spin resonance (ESR) spectroscopy indicated that the thiol group attached to the chromophore does not influence the photochemical process to generate primary radicals. The photoinitiation of α‐aminoalkylphenone can be spectrally sensitized by 2,4‐diethylthioxanthone (DETX). However, thiol‐substituted α‐aminoalkylphenone showed smaller spectral sensitization than the corresponding compound without a thiol group. Time resolved laser flash photolysis indicated that the rate constant of the quenching of the triplet state of DETX by thiol‐substituted α‐aminoalkylphenone is twice as large as that by the corresponding one without a thiol group. This suggests that, besides energy transfer from DETX in the excited triplet state to the α‐aminoalkylphenone, the thiol group quenches the excited triplet state of DETX via charge transfer and/or hydrogen transfer, as supported by the ESR analysis using a spin trapping technique, and lowers the efficiency of the spectral sensitization effect. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1684–1695, 2005     

The exo and endo isomers of [N,N′‐bis­(salicyl­idene)‐1,2‐di­phenyl‐(RS,SR)‐1,2‐ethane­diyl­diamin­ato]­oxo­vanadium(IV)

The title complexes, exo‐ and endo‐[VO(C₂₈H₂₂N₂O₂)], show monomeric structures with a distorted square‐pyramidal coordination. The two phenyl groups on the five‐membered N,N′‐chelate ring are both on the same side as the oxo ligand for the exo isomer and on opposite sides for the endo isomer.     

Reductive alkylation of indoles with alkynes and hydrosilanes under indium catalysis

Under Indium catalysis, diverse alkylindoles were successfully prepared with a flexible combination of indoles and alkynes in the presence of hydrosilanes. In addition to the hydrosilane, carbon nucleophiles are also available. This new method generates alkylindoles in yields over 70% with a broad scope of functional group compatibility.