Remote asymmetric induction with vinylketene silyl n,o-acetal

A highly regio- and diastereoselective TiCl4-mediated vinylogous Mukaiyama aldol reaction using the chiral vinylketene silyl N,O-acetal has been developed. The present vinylogous Mukaiyama aldol reaction provides a unique and effective means of controlling remote asymmetric induction. The methyl group at the alpha-position is important in achieving a high level of stereoselectivity. From a synthetic point of view, this methodology can provide a one-step construction of delta-hydroxy-alpha,gamma-dimethyl-alpha,beta-unsaturated carbonyl unit that is seen in many natural polyketide products.     

A highly efficient asymmetric Suzuki-Miyaura coupling reaction catalyzed by cationic chiral palladium(ii) complexes

Cationic chiral palladium(ii) complexes are shown to catalyze the asymmetric coupling reaction of aryl boronates and aryl halides within a short period of time in good yield and enantioselectivity.     

On a p-Local Geometry Associated with a Complex of Non-Trivial p-Subgroups

Let D be a complex of non-trivial p-subgroups of a finite groupG, closed under G-conjugation. In this paper, a p-local geometry^p(G; D) is introduced for G associated with the complex D. Thehomotopy equivalence between ^p(G; D) and D is also studied.2000 Mathematics Subject Classification 20E15, 51E24.     

Synthesis and properties of multiblock copoly(arylene ether)s containing superacid groups for fuel cell membranes

A series of block copoly(arylene ether)s containing pendant superacid groups were synthesized, and their properties were investigated for fuel cell applications. Two series of telechelic oligomers, iodo‐substituted oligo(arylene ether ketone)s and oligo(arylene ether sulfone)s, were synthesized. The degree of oligomerization and the end groups were controlled by changing the feed ratio of the monomers. The nucleophilic substitution polymerization of the two oligomers provided iodo‐substituted precursor block copolymers. The iodo groups were converted to perfluorosulfonic acid groups via the Ullmann coupling reaction. The high degree of perfluorosulfonation (up to 83%) was achieved by optimizing the reaction conditions. Tough and bendable membranes were prepared by solution casting. The ionomer membranes exhibited characteristic hydrophilic/hydrophobic phase separation with large hydrophilic clusters (ca. 10 nm), which were different from that of our previous random copolymers with similar molecular structure. The block copolymer structure was found to be effective in improving the proton‐conducting behavior of the superacid‐modified poly(arylene ether) ionomer membranes without increasing the ion exchange capacity (IEC). The highest proton conductivity was 0.13 S/cm at 80 °C, 90% relative humidity, for the block copolymer ionomer membrane with IEC = 1.29 mequiv/g. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Mathematical analogy of a beam on elastic supports as a beam on elastic foundation

This paper presents the mathematical hypothesis that a beam on equidistant elastic supports (BOES) can be considered as a beam on an elastic foundation (BOEF) in static and free vibration problems. This modeling of BOES as BOEF is presumed to be applicable to a limited range of support stiffness, spacing and flexural rigidity of the beam. The authors investigate the applicability of the modeling of BOEF from the property of characteristic solutions obtained from governing equations of both BOES and BOEF. In this study, the formulation of BOES leads to governing difference equations, and the motions of BOEF are expressed by differential equations. This is because exact solutions must be employed in order to verify their analogy accurately. The characteristic solutions obtained from these two governing equations are compared to each other in order to investigate the relationship between them.     

Nanosecond Time-Gated Spectroscopy of Laser-Ablation Plume of Human Hair to Detect Calcium for Potential Diagnoses

We demonstrate the nanosecond time-gated spectroscopy of plume luminescence in UV laser ablation of human hair. Clear and sharp peaks of calcium ion (Ca⁺) appear in the spectrum although the Ca content is only 0.1% in human hair. Highly sensitive detection of Ca is thus possible. In the experiment, the peak intensity of Ca⁺ was measured for human hair samples of female subjects over a wide range of age, and compared to the bone mineral density of the lumbar vertebrae of the subjects themselves. Our experimental results suggest that this specific spectroscopy has the potential for novel diagnoses including monitoring of daily Ca intake and a screening diagnosis of osteoporosis. The spectroscopic system and time transition of plume-luminescence spectra are also described.