Homohelicity induction of propylene-linked zinc bilinone dimers by complexation with chiral amine and α-amino esters. Preorganization of structurally coupled homohelical subunits

Homohelicity induction of a series of propylene-linked zinc bilinone (ZnBL; linear tetrapyrrople-zinc(II) complex) dimers upon complexation with chiral amine and α-amino esters was investigated. Introduction of substituents such as dimethyl and diisobutyl to the central carbon of the propylene spacer gave rise to stabilization of the homohelical (PP and MM) conformers rather than the heterohelical (PM) conformer. As bulkiness of the substituent increased, stability of the homohelical conformers was raised. The preorganization of the homohelical structures led to significantly amplified homohelicity induction upon complexation with chiral amine and α-amino esters.     

Probing for electrical inclusions with complex spherical waves

Let a physical body Ω in ?² or ?³ be given. Assume that the electric conductivity distribution inside Ω consists of conductive inclusions in a known smooth background. Further, assume that a subset Γ ? ?Ω is available for boundary measurements. It is proved using hyperbolic geometry that certain information about the location of the inclusions can be exactly recovered from static electric measurements on Γ. More precisely: given a ball B with center outside the convex hull of Ω and satisfying (B? ∩ ?Ω) ? Γ, boundary measurements on Γ with explicitly given Dirichlet data are enough to determine whether B intersects the inclusion. An approximate detection algorithm is introduced based on the theory. Numerical experiments in dimension two with simulated noisy data suggest that the algorithm finds the inclusion‐free domain near Γ and is robust against measurement noise. © 2007 Wiley Periodicals, Inc.     

Design of polarization retarder suitable for nonlinear optical systems

We present a design technique of retarders suitable for nonlinear optical systems. A thin sample of LiNbO₃ crystal is utilized as a retarder for wide-ranging applications. Analysis shows that the same crystal can be used for single-wave or two-wave retardations, changing the orientation of the crystal only. As an application, the retarder is used to polarize two waves orthogonal, as necessary for difference frequency mixing in an AgGaSe₂ crystal.     

The representation type of Hecke algebras of type B

This paper determines the representation type of the Iwahori-Hecke algebras of type B when q≠±1. In particular, we show that a single parameter non-semisimple Iwahori-Hecke algebra of type B has finite representation type if and only if q is a simple root of the Poincaré polynomial, confirming a conjecture of Uno's (J. Algebra 149 (1992) 287).     

Liquid crystal lens with focus movable in focal plane

A liquid crystal lens with focus movable in the focal plane is reported. There are three electrodes in the cell. One electrode with a hole in the center is divided into four subelectrodes. The potential of each subelectrode is adjusted to produce a desired asymmetrical phase transformation resulting in off-axis movement of the focus. The potential of another electrode is adjusted to maintain the focus in the focal plane. Movements of the focus in three directions in the focal plane are demonstrated experimentally, and off-axis movement as large as approximately 800 μm is realized.     

Effects of natural polysaccharide addition on drug release from calcium-induced alginate gel beads

Calcium-induced alginate gel beads (Alg-Ca) containing various polysaccharides, including an alginate hydrolysate, were prepared and the drug release profiles were investigated. Hydrocortisone (HC) was gradually released from Alg-Ca into the mimic gastric fluid, while in intestinal fluid, it was quickly released with the dissolution of Alg-Ca. However, with Alg-Ca containing 5% chitin (CT), dissolution of Alg-Ca was not observed, and release of HC showed apparent zero-order kinetics. Furthermore, addition of the alginate hydrolysate altered the HC-release profile for Alg-Ca.     

Electron microscope study of viscoelastic cationic surfactant systems

Some cationic surfactants such as cetyltrimethylammonium bromide (CTAB) show a very spectacular viscoelasticity in solution, in even very diluted states, with some aromatic substances added, such as salicylic acid. Formerly, the authors established that the remarkable solution behaviour was the result of the entanglement of such enormously elongated giant micelles, based on recognition of the existence of large aggregates, through direct observation of them as substantial images under the electron microscope.In this report, we further confirm the relation between micelle length and solution viscoelasticity after arbitrarily obtaining different size aggregates by altering the media pH, or by admixing shorter chain length surfactants than CTAB, which alone did not induce viscoelasticity.     

Regioselective synthesis of virazole using benzyl cyanoformate as a synthon

An antiviral nucleoside or virazole was synthesized efficiently and regioselectively starting with benzyl cyanoformate.     

An efficient conversion of 1-abietic acid to (+)−3-deoxyaphidicolin

The first total synthesis of (+)?3-deoxyaphidicolin, a selective inhibitor of eukaryotic DNA polymerase α, has been completed efficiently and stereoselectively starting from 1-abietic acid.