Azo benzene derivatives

Pressure-volume isotherms for 4-(trans-4-butylcylohexyl)benzonitrile were measured by means of piston-cylinder method. This substance has a monotropic nematic phase at atmospheric pressure. But over a pressure, the nature of isotropic to nematic phase transition changed from monotropic to enantiotropic phase transition. It is the first observation in P-V-T experiments that the monotropic isotropic-nematic transition changes enantiotropic under pressure.     

Asymptotic profiles of steady Stokes and Navier–Stokes flows around a rotating obstacle

We analyze the spatial anisotropic profiles at infinity of steady Stokes and Navier–Stokes flows around a rotating obstacle. It is shown that the Stokes flow is largely concentrated along the axis of rotation in the leading term and that a rotating profile can be found in the second term. The leading term for Navier–Stokes flow will be an adequate Landau solution. The proofs rely upon a detailed analysis of the associated fundamental solution tensor.     

Tactile impression and friction of water on human skin

Water has a unique touch as well as characteristic physical properties. However, nobody knows the real identity of its touch. Here, we show that water creates a stick-slip feel when a small amount is rubbed using fingertip on an artificial skin that mimics the structure of human skin. The results of frictional analyses predict that this stick-slip feel is caused by a drastic change in frictional resistance. The present result is valuable for biologists and robot engineers as well as cognitive scientists and tribologists, because it is a new example of stick-slip phenomena on biological surfaces. The tactile texture of this most familiar material could also be applied to consumer products or virtual reality systems.     

A characterization of isotropic immersions by extrinsic shapes of smooth curves

In this paper we show that an isometric immersion is isotropic in the sense of O'Neill if and only if it preserves logarithmic derivatives of first geodesic curvatures of some curves.     

Degradation of aliphatic-aromatic copolyesters by bacteria that can degrade aliphatic polyesters

The degradation activities of bacteria that can degrade aliphatic polyesters on various aliphatic-aromatic copolyesters (PBSTIL, PBST, and Ecoflex™) were investigated. Among the bacteria examined, strain TB-71 showed the best degradation activity. An HPLC analysis of the degradation products revealed that PBST55 and Ecoflex™ are degraded into monomers by strain TB-71. In the case of PBSTIL, an unknown peak was detected by the HPLC analysis and was considered to be derived from water-soluble oligomers containing isophthalic acid segments. This finding seemed to be attributed to the chemical structure of the aromatic segments of the copolymers.     

Kinetic and equilibrium studies of urea adsorption onto activated carbon: Adsorption mechanism

We found that activated carbon effectively removed urea from solution and that urea adsorption onto activated carbon followed a pseudo-second-order kinetic model. We classified the urea adsorption on activated carbon as physical adsorption and found that it was best described by the Halsey adsorption isotherm, suggesting that the multilayer adsorption of urea molecules on the adsorption sites of activated carbon best characterized the adsorption system. The mechanism of adsorption of urea by activated carbon involved two steps. First, an amino (–NH₂) group of urea interacted with a carbonyl (–C?O) group and a hydroxyl (?OH) group on the surface of activated carbon via dipole–dipole interactions. Next, the –C?O group of the urea molecule adsorbed to the activated carbon interacted with another –NH₂ group from a second urea molecule, leading to multilayer adsorption.     

Development and photo-responsive peptide bond cleavage reaction of two-photon near-infrared excitation-responsive peptide

Two-photon near-infrared excitation-responsive amino acid was developed. It was incorporated into a peptide, and focused near-infrared pulsed laser irradiation-induced peptide bond cleavage reaction at the C-terminal position of the photo-responsive amino acid was observed.     

The reaction of 1-silylcyclopropyl anions with dichloromethyl methyl ether: the efficient synthesis of cyclopropyl silyl ketones via cyclopropylidene derivatives

The reaction of 1-silylcyclopropyl anions with dichloromethyl methyl ether is described. The reaction with an excess amount of dichloromethyl methyl ether gives the corresponding cyclopropyl silyl ketones in low yields. On the other hand, the reaction under basic conditions proceeded smoothly to afford the corresponding cyclopropylidene derivatives, exclusively. The resulting cyclopropylidene compounds are subjected to hydrolysis or trapping with electrophiles easily to give the cyclopropyl silyl ketone derivatives in good yields.