Correlation between dynamic heterogeneity and medium-range order in two-dimensional glass-forming liquids

A glassy state of matter results if crystallization is avoided upon cooling or increasing density. However, the physical factors controlling the ease of vitrification and nature of the glass transition remain elusive. Using numerical simulations of polydisperse hard disks, we find a direct relation between medium-range crystalline ordering and the slow dynamics which characterizes the glass transition. This suggests an intriguing scenario that the strength of frustration controls both the ease of vitrification and nature of the glass transition. Vitrification may be a process of hidden crystalline ordering under frustration, at least in our system.     

On a new construction of geometric mean of -operators

For n positive definite operators A₁,…,A_n, Ando-Li-Mathias defined geometric mean of n-operators by symmetric procedure. It has many nice properties, and is studied by many authors. But the process is so complicated to compute. In this paper, we shall attempt to make a new construction of geometric mean of n-operators which we can compute it easier than geometric mean by Ando–Li–Mathias.     

Polyaniline–DNA microsphere formation by simple electropolymerization

Polyaniline (PANI) microspheres were prepared by electrochemical polymerization. To obtain PANI having novel micro- and nanostructures, by the potential scan technique, aniline was electropolymerized in the presence of DNA using four polymerizing solutions containing different acids: H₂SO₄, C₆H₅SO₃H, HClO₄, and CF₃COOH. The growth rate of the PANI film on the electrode surface decreased by the presence of DNA, suggesting that DNA interacted with the growing PANI molecules during the electropolymerization. The growth rate also depended on the type of acid, i.e., the anion, in the polymerizing solution and was in the order of SO₄ ²⁻ > C₆H₅SO₃ ⁻ > ClO₄ ⁻ > CF₃COO⁻, which significantly coincided with the reverse order of the Hofmeister series representing the lyophilicity of the anion. When aniline was electropolymerized in the CF₃COOH polymerizing solution containing DNA, PANI microspheres were obtained without any templates. This PANI showed a sufficient redox activity in the less acidic solution in which the ordinary PANI has a slight redox activity. On the other hand, the electronic state of the PANI differed from the ordinary ones; a new absorption band was evident at 620 nm. The difference in the redox activity and electronic state suggested that the DNA molecules were incorporated in the PANI and electronically interacted with the PANI molecules.     

Scale-model experiments of moving fire whirl over a line fire

A fire whirl, observed during a wildland fire in Brazil in 2010, occurred over a narrow but long line fire and moved along the line fire at nearly a constant speed. There appeared to be no mountains, tall buildings or trees near the scene, indicating that the fire whirl was generated merely by the interaction between the line fire and background wind. Scale-model experiments having different line fire configurations were designed and performed to reconstruct the above-mentioned Brazil fire whirl. Moving fire whirls were successfully reconstructed during the scale-model experiments, the mechanism and conditions of which are discussed herein.     

Ligand dependence of pi-complex character in disilene-palladium complexes

The synthesis and structures of new 16-electron disilene palladium complexes with 2,6-dimethylphenyl isocyanide and phenyldimethylphosphine ligands [L(1)L(2)Pd{(t-BuMe(2)Si)(2)Si=Si(SiMe(2)Bu-t)(2)}, where L(1) = L(2) = PhMe(2)P; L(1) = (cyclohexyl)(3)P, L(2) = 2,6-dimethylphenyl isocyanide; L(1) = L(2) = 2,6-dimethylphenyl isocyanide] are described. Comparison of the X-ray structural parameters around the disilene moiety among these complexes and related bis(trimethylphosphine)(disilene)palladium and 14-electron (tricyclohexylphosphine)(disilene)palladium revealed that the pi-complex character is sensitive to the residual ligands and increases with decreasing the strength of sigma-donation from the ligands.     

Selectively substituted thiophenes and indoles by a tandem palladium-catalyzed multicomponent reaction

A variety of di- and trisubstituted thiophenes were synthesized by a one-pot palladium-catalyzed ortho-alkylation sequence terminated by either Heck or C-H coupling. Initial results toward the functionalization of indoles are also presented.