Kink dynamics in one-dimensional nonlinear systems

A certain class of nonlinear evolution equations of one space dimension which permits kink type solutions and includes one-dimensional time-dependent Ginzburg-Landau (TDGL) equations and certain nonlinear wave equations is studied in some strong coupling approximation where the problem can be reduced to the study of kink dynamics. A detailed study is presented for the case of TDGL equation with possible applications to the late stage kinetics of order-disorer phase transitions and spinodal decompositions. A special case of kink dynamics of nonlinear wave equations is found to reduce to the Toda lattice dynamics. A new conservation law for dissipative systems is found which corresponds to the momentum conservation law for wave equations.     

Lower bounds on the cardinality of the maximum matchings of planar graphs

Lower bounds on the cardinality of the maximum matchings of planar graphs, with a constraint on the minimum degree, are established in terms of a linear polynomial of the number of vertices. The bounds depend upon the minimum degree and the connectivity of graphs. Some examples are given which show that all the lower bounds are best possible in the sense that neither the coefficients nor the constant terms can be improved.     

Structure of holothurin A a biologically active triterpene-oligoglycoside from the sea cucumber holothuria leucospilota brandt

On the basis of chemical and physicochemical evidence, the structure of holothurin A, a biologically active major obligoglycoside o lanostane-type triterpene holothurigenol ($\text{2}$), has been elucidated to be $\text{8}$.     

Hydrogen-bonding abilities for phenols assessed by quantitative analyses of their partition coefficients derived from different partitioning systems

We recently proposed a new hydrogen-accepting scale, S(HA), on the basis of the heat of formation calculated by the conductor-like screening model (COSMO) method. In this work, the same approach was applied to a series of compounds with a common hydrogen-donor group. Thus the S(HA) values for monosubstituted phenols were calculated and used for correlating their log P(oct) values (P(oct): 1-octanol/water partition coefficient) with log P(CL) (P(CL): chloroform/water partition coefficient) and log P(E) (P(E): butyl ether/water partition coefficient). It was demonstrated that the S(HA) parameter works effectively, providing excellent correlations whose physicochemical meanings are well rationalized in terms of hydrogen-bonding characteristics of the substituents.     

Synthesis of photoactivatable acyclic analogues of the lobatamides

[structure: see text] The lobatamides and related salicylate enamide natural products are potent mammalian V-ATPase inhibitors. To probe details of binding of the lobatamides to mammalian V-ATPase, three photoactivatable analogues bearing benzophenone photoaffinity labels have been prepared. The analogues were designed on the basis of a simplified acyclic analogue 2. Late-stage installation of the enamide side chain and tandem deallylation/amidation were employed in synthetic routes to these derivatives. Simplified analogue 2 showed strong inhibition against bovine clathrin-coated vesicle V-ATPase (10 nM). Analogues 3-5 were also evaluated for inhibition of bovine V-ATPase in order to select a suitable candidate for future photoaffinity labeling studies.     

Hurwitz and Tasoev Continued Fractions

The continued fractions studied by Tasoev are not widely known although their characteristics are very similar to those of Hurwitz continued fractions. Recently, the author found several general forms of Tasoev continued fractions, and by applying this method he also obtained some more general forms of Hurwitz continued fractions belonging to so called tanh-type and tan-type. In this paper, we constitute a new class of general forms of Hurwitz continued fractions of e-type. The known continued fraction expansions of e^1/a (a 1), ae^1/a and (1/a)e^1/a are included as special cases. The corresponding Tasoev continued fractions are also derived.     

Hurwitz and Tasoev Continued Fractions

The continued fractions studied by Tasoev are not widely known although their characteristics are very similar to those of Hurwitz continued fractions. Recently, the author found several general forms of Tasoev continued fractions, and by applying this method he also obtained some more general forms of Hurwitz continued fractions belonging to so called tanh-type and tan-type. In this paper, we constitute a new class of general forms of Hurwitz continued fractions of e-type. The known continued fraction expansions of e^1/a (a 1), ae^1/a and (1/a)e^1/a are included as special cases. The corresponding Tasoev continued fractions are also derived.     

Volume collapsed three-manifolds with a lower curvature bound

In this paper we determine the topology of three-dimensional complete orientable Riemannian manifolds with a uniform lower bound of sectional curvature whose volume is sufficiently small.     

Homolytic alkylthiyldealkylation of mixed alkylboranes

The relative ease of displacement of different alkyl groups in mixed alkylboranes by butylthiyl radicals derived from butanethiol follows the sequence p-R < s-R < t-R.