New 5-designs with automorphism group PSL(2, 23)

Blocks of the unique Steiner system S(5, 8, 24) are called octads. The group PSL(2, 23) acts as an automorphism group of this Steiner system, permuting octads transitively. Inspired by the discovery of a 5-(24, 10, 36) design by Gulliver and Harada, we enumerate all 4- and 5-designs whose set of blocks are union of PSL(2, 23)-orbits on 10-subsets containing an octad. © 1999 John Wiley & Sons, Inc. J Combin Designs 7: 147–155, 1999     

Synthesis of 4‐(7‐diethylaminocoumarin‐3‐yl)benzeneisocyanate (DACB‐NCO): A highly sensitive fluorescent derivatization reagent for alcohols in high‐performance liquid chromatography

4‐(7‐Diethylaminocoumarin‐3‐yl)benzeneisocyanate (DACB‐NCO) was synthesized as a new fluorescent derivatization reagent for alcohols for use in high‐performance liquid chromatography (hplc). Saturated alcohols (C₆‐C₂₂) were derivatized in good yields into the corresponding fluorescent DACB‐carbamic esters by treating with DACB‐NCO. The DACB‐carbamic esters of these alcohols were clearly separated on a reversed‐phase hplc column (Inertsil ODS‐2, mobile phase: methanol‐water, excitation wavelength 402 nm; emission wavelength 488 nm). The detection limit (S/N = 3) of cetyl alcohol, as a test compound, was 5 fmol/10 μl.     

Near-infrared spectra of formamide and its anharmonic potential

The near-infrared spectra of formamide and its N- and C-deuterated compounds in chloroform solutions were investigated and a perturbation calculation of the vibrational levels of these isotopic formamides was carried out. The trans-interaction constant and the cubic cross-term constants between the NH stretching and the CNH bending coordinates were found to be necessary to reproduce observed frequencies. The stretching potentials of the trans- and the cis-NH bonds show close correspondence with those of the free and the bonded NH bonds of o-bromoaniline. The correlation between the compliance constants and the change of the CH, CO, and NH bond lengths on the dissociation of the CN bond is discussed.     

A Correction to “Incidence Matrices and Collineations of Finite Projective Planes” by Chat Yin Ho, Designs, Codes and Cryptography, 18 (1999), 159–162

In this note we consider the set of incidence matrices of a cyclic projective planes whose set of points has cardinality a prime number p. We provide a correct proof of a result of Ho, showing that there exists an incidence matrix that possesses exactly p distinct eigenvalues.     

Persistent spectral hole‐burning study on dendrimer porphyrins

We report the first results of persistent spectral hole burning of dendrimer porphyrins having three‐, four‐, or five‐layered aryl ether dendritic arrays. We evaluate structural relaxations of dendrimer framework around the porphyrin core at low temperatures. A large environmental change around the porphyrin core, as evaluated from the hole area, was suppressed in dendrimer porphyrins of higher generation numbers, whereas a small environmental change, as evaluated from hole width, showed no dependence on the number of generations. The dendrimer porphyrins showed sharp holes at 20 K, suggesting a long dephasing time and the suppression of spontaneous spectral diffusion. The results of dendrimer‐embedded polymer sample indicated that the structural relaxation of polymer chain outside the dendrimer does not have an influence on the resonant frequency of the porphyrin core. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 210–215, 2002     

Direct Enantiomeric Purity Determination of Acetyl-L-carnitine by LC with a Ligand-Exchange Chiral Stationary Phase

A direct HPLC method for the determination of acetyl-D-carnitine in acetyl-L-carnitine was investigated. The enantiomers were successfully separated on a SUMICHIRAL OA-6100 column, which has a ligand-exchange type of chiral moiety. The mobile phase consisted of an aqueous solution of copper (II) sulfate and sodium perchlorate. Successful enantioseparation seems to be achieved through the formation of not only the complex with copper (II) ion but also by ion-pairing with the perchlorate ion, because no enantioseparation was observed with the usual copper (II) mobile phase alone. Employing 2 mM aqueous CuSO₄ solution containing 500 mM NaClO₄, the enantiomers of acetylcarnitine eluted in the order of D- and L-forms within 15 min with R _s = 1.92 and α = 1.11. The obtained LOQ and LOD values were 0.15 and 0.1%, respectively. The validated results were satisfactory for a practical quality control method for the enantiomeric purity determination of acetyl-L-carnitine.