Classification of extremal contractions from smooth fourfolds of -type

We investigate divisorial contractions of extremal rays from
smooth fourfolds. When the exceptional divisor is contracted to a curve, we prove that the divisor is a -bundle or quadric bundle over a smooth curve and the contraction is the blowing up along the curve. Furthermore we determine the local analytic structure of the contraction.

     

Calorimetric determination of enthalpies,gibbs energies,and entropies of inclusion of some alcohols into α- and β-cyclodextrins in aqueous solutions

The enthalpies of transfer of cyclohexanol from aqueous to aqueous - or -cyclodextrin solutions have been measured at various mole fractions at 298.15 K on a rocking twin-microcalorimeter of heat-conduction type and the molar enthalpies, Gibbs energies, and entropies of inclusion in the aqueous solutions have been determined by the method proposed by the authors [Netsu Sokutei 10, 103 (1983)], to elucidate the driving force of the molecular inclusion. Discussions are given for all the systems obtained by the authors, concluding that the driving force is the enhancement of the entropy.Calorimetric studies on molecular inclusion V.     

Avenic acid,a new amino acid possessing an iron chelating activity

A new amino acid derivative possessing an iron chelating activity was isolated from root washings of water cultured $\text{Avena sativa}$ under iron deficient conditions. The structure of this compound, avenic acid A has been determined as 2(S),3′(S),3″(S)-N-[3-(3-hydroxy-3-carboxypropylamino)-3-carboxypropyl]-homoserine (1) on the basis of chemical and spectroscopic evidence.     

Novel soft chemical method for optically transparent Ru(bpy)3-K4Nb6O17 thin film

A unique guest-guest ion exchange method was developed for preparing a thin film of a nano-layered K(4)Nb(6)O(17).3H(2)O that possesses both (1) optical transparency and (2) ion-exchangeability under ambient conditions without calcination at high temperature. An optically transparent Ru(bpy)(3)(2+)-K(4)Nb(6)O(17) hybrid thin film, a photoresponsive electrode, was successfully prepared by the guest-guest exchange method by use of the intercalation compound MV(2+)-K(4)Nb(6)O(17) as a precursor. The optically transparent Ru(bpy)(3)(2+)-K(4)Nb(6)O(17) hybrid thin films have been characterized by X-ray diffraction, SEM, AFM, IR, and UV spectroscopies, as well as elemental analysis. The electrochemical behavior of the ITO/Ru(bpy)(3)(2+)-K(4)Nb(6)O(17) hybrid thin film electrode was studied; it also exhibits swift photoresponse in the visible region.     

Texture in the superconducting order parameter of CeCoIn5 revealed by nuclear magnetic resonance

We present a 115In NMR study of the quasi-two-dimensional heavy-fermion superconductor CeCoIn5 believed to host a Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) state. In the vicinity of the upper critical field and with a magnetic field applied parallel to the ab plane, the NMR spectrum exhibits a dramatic change below T*(H) which well coincides with the position of reported anomalies in specific heat and ultrasound velocity. We argue that our results provide the first microscopic evidence for the occurrence of a spatially modulated superconducting order parameter expected in a FFLO state. The NMR spectrum also implies an anomalous electronic structure of vortex cores.     

Iridium complex-catalyzed highly enantio- and diastereoselective [2+2+2] cycloaddition for the synthesis of axially chiral teraryl compounds

An asymmetric [2+2+2] cycloaddition of an alpha,omega-diyne, possessing ortho-substituted aryl groups on its terminus, and a monoalkyne with oxygen functionalities gave various axially chiral teraryl compounds. The coupling proceeded with extremely high enantio- (>99.5% ee) and diastereoselectivities (dl/meso = >95/5) when catalyzed by an iridium-chiral phosphine complex. As the products were readily transformed into diol compounds by deprotection without racemization, the present procedure provides access to a new chiral pool of diol compounds with C2 symmetry.     

Interpretation of Hund's multiplicity rule for the carbon atom

Hund's multiplicity rule is investigated for the carbon atom using quantum Monte Carlo methods. Our calculations give an accurate account of electronic correlation and obey the virial theorem to high accuracy. This allows us to obtain accurate values for each of the energy terms and therefore to give a convincing explanation of the mechanism by which Hund's rule operates in carbon. We find that the energy gain in the triplet with respect to the singlet state is due to the greater electron-nucleus attraction in the higher spin state, in accordance with Hartree-Fock calculations and studies including correlation. The method used here can easily be extended to heavier atoms.     

Observation of a liquid-gas-type transition in the pyrochlore spin ice compound Dy2Ti2O7 in a magnetic field

Low temperature magnetization measurements on the pyrochlore spin ice compound Dy2Ti2O7 reveal that the ice-rule breaking spin flip, appearing at H approximately 0.9 T applied parallel to the [111] direction, turns into a novel first-order transition for T<0.36 K which is most probably of a liquid-gas type. T-linear variation of the critical field observed down to 0.03 K suggests the unusual situation that the entropy release across the transition remains finite [approximately 0.5 (J/K) x mol-Dy] as T-->0, in accordance with a breaking of the macroscopic degeneracy in the intermediate "kagomé ice" state.