Two-dimensional and three-dimensional Fermi surfaces of superconducting BaFe2(As(1-x)P(x))2 and their nesting properties revealed by angle-resolved photoemission spectroscopy

We have studied the three-dimensional shapes of the Fermi surfaces (FSs) of BaFe(2)(As(1-x)P(x))(2) (x=0.38), where superconductivity is induced by isovalent P substitution and by angle-resolved photoemission spectroscopy. Moderately strong electron mass enhancement has been identified for both the electron and hole FSs. Among two observed hole FSs, the nearly two-dimensional one shows good nesting with the outer two-dimensional electron FS, but its orbital character is different from the outer electron FS. The three-dimensional hole FS shows poor nesting with the electron FSs. The present results suggest that the three dimensionality and the difference in the orbital character weaken FS nesting while partial nesting among the outer electron FSs of d(xy) character and/or that within the three-dimensional hole FS becomes dominant, which may lead to the nodal superconductivity.     

Formation mechanism of element distribution in glass under femtosecond laser irradiation

We report on the formation mechanism of element distribution in glass under high-repetition-rate femtosecond laser irradiation. We simultaneously focused two beams of femtosecond laser pulses inside a glass and confirmed the formation of characteristically shaped element distributions. The results of the numerical simulation in which we considered concentration- and temperature-gradient-driven diffusions were in excellent qualitative agreement with the experimental results, indicating that the main driving force is the sharp temperature gradient. Since the composition of a glass affects its refractive index, absorption, and luminescence property, the results in this study provide a framework to fabricate a functional optical device such as optical circuits with a high-repetition-rate femtosecond laser.     

Mixture diffusion of sulfonated dyes into cellulose membrane. III. Application of parallel diffusion model to binary system of direct dyes with different affinity

Mixture diffusion of two dyes (C.I. Direct Blue 15 (DB15) and C.I. Direct Yellow 12 (DY12)) with different affinity onto the substrate into cellulose membrane from the binary solution was studied at 55°C. Uptake curves and concentration–distance profiles were measured experimentally in the ratios (DB15:DY12) 1:0.5, 1:1 and 1:2. It was examined whether the diffusion of the dyes could be analyzed based on the parallel diffusion theory of surface and pore diffusion. It was revealed that the diffusion of DB15 with higher affinity could be analyzed based on the model in the ratios 1:0.5 and 1:1, although the theoretical value deviated slightly from the data in the concentration–distance profile in the ratio 1:1. On the other hand, the diffusion of DY12 with smaller affinity could not be described by the model, because the diffusivity of the dye changed during the adsorption process against the assumption of the model.     

Structure and dynamics of polymeric materials in nano-scale

The nano-palpation technique,i.e.,nanometer-scale elastic and viscoelastic measurements based on atomic force microscope,is introduced.It is demonstrated to be very useful in analyzing nanometer-scale materials properties for the surfaces and interfaces of various types of soft materials.It enables us to obtain not only structural information but also mechanical information about a material at the same place and at the same time.     

2-reducible cycles containing three consecutive edges in (2k + 1)-edge-connected graphs

LetG be ak-edge-connected graph and letf ₁,f ₀,f ₂ be consecutive edges. We call a cycleC (not necessarily simple) 2-reducible ifG – E(C) is (k – 2)-edge-connected. We here characterize the graphsG having no 2-reducible cycle containingf ₁,f ₀ andf ₂.     

Spontaneous Formation of Microgroove Arrays on the Surface of p‐Type Porous Silicon Induced by a Turing Instability in Electrochemical Dissolution

Self‐organization plays an imperative role in recent materials science. Highly tunable, periodic structures based on dynamic self‐organization at micrometer scales have proven difficult to design, but are desired for the further development of micropatterning. In the present study, we report a microgroove array that spontaneously forms on a p‐type silicon surface during its electrodissolution. Our detailed experimental results suggest that the instability can be classified as Turing instability. The characteristic scale of the Turing‐type pattern is small compared to self‐organized patterns caused by the Turing instabilities reported so far. The mechanism for the miniaturization of self‐organized patterns is strongly related to the semiconducting property of silicon electrodes as well as the dynamics of their surface chemistry.