N-fused pentaphyrins (NFP5), stable forms of meso-aryl pentaphyrins, are interesting platforms to realize Hückel aromaticity, nonaromaticity, and Möbius aromaticity depending upon the number of π-electrons, meso-substituent, and metalation. Remarkably, Rh(I) complex of pentakis(pentafluorophenyl) substituted [24]NFP5 has been characterized as a Möbius aromatic macrocycle by the crystal structure, 1H NMR spectrum, NICS calculation, and two-photon absorption (TPA) cross section. This system is, to the best of our knowledge, the smallest Möbius aromatic molecule with a distinct diatropic ring current characterized so far. This work demonstrates the great potential of our synthetic strategy toward Möbius aromatic molecules as well as the possible use of TPA value as a quantitative measure of aromaticity.

Starting from a 1,3-phenylene-linked diporphyrin zinc(II) complex 2ZA, repeated stepwise Ag(I)-promoted coupling reactions provided linear oligomers 4ZA, 6ZA, 8ZA, and 12ZA. The intramolecular cyclization reaction of 12ZA under dilute conditions (1x10(-6) M) gave porphyrin ring C12ZA with a diameter of approximately 35 A in 60% yield. This synthetic strategy has been applied to a 1,3-phenylene-linked tetraporphyrin 4ZB to provide 8ZB, 12ZB, 16ZB, 24ZB, and 32ZB. The intramolecular coupling reaction of 24ZB gave a larger 24-mer porphyrin ring C24ZB with a diameter of approximately 70 A in 34% yield. These two large porphyrin rings were characterized by means of 1H NMR spectroscopy, matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectroscopy, UV-visible spectroscopy, gel permeation chromatography (GPC) analysis, and scanning tunneling microscopy (STM) techniques. The STM images of C12ZA reveal largely circular structures, whereas those of C24ZB exhibit mostly ellipsoidal shapes, indicating more conformational flexibility of C24ZB. Similar to the case of C12ZA, the efficient excitation energy transfer along the ring has been confirmed for C24ZB by using the time-correlated single-photon counting (TCSPC) and picosecond transient absorption anisotropy (TAA) measurements, and occurs with a rate of (35 ps)(-1) for energy hops between neighboring tetraporphyrin subunits. Collectively, the present work provides an important step for the construction of large cyclic-arranged porphyrin arrays with ample electronic interactions as a model of light-harvesting antenna.

Acetylacetone in the supersonic jet, which exists predominantly as an enolic form, is found to give rise to the OH fragment after the -* transition induced by the UV absorption. The nascent OH product state distributions are determined using a laser-induced fluorescence technique at the excitation wavelengths of 291 and 266 nm. The OH fragment is vibrationally cold, and its rotational state distribution is peaked at Nϭ3 or 4 at the pump wavelength of 291 or 266 nm, respectively. No fluorescence from the excited acetylacetone has been observed even in the energy region near the origin, suggesting the ultrafast nonradiative processes of the excited state. From the measured OH product state distributions, the upper bound for the dissociation energy of the acetylacetone is estimated to be 90.3 kcal/mol. The ratios of ⌳-doublets and spin-orbit states of the OH fragment are also measured. A slight preference of the OH fragment in the 2 ⌸ 3/2 state over the 2 ⌸ 1/2 state is observed. The ⌸ Ϫ /⌸ ϩ ratios, determined by the relative intensity ratios of Q and P ͑or R͒ lines, are found to be less than unity, suggesting the preferential cleavage of the C-OH bond on the molecular plane probably due to a relatively strong intramolecular hydrogen bonding of the enolic acetylacetone. The prior calculation reproduces the experiment quite well for the OH rotational state distribution at 291 nm, while it does not for that at 266 nm. This suggests that the transition state in the acetylacetone dissociation, at the low energy near threshold, may be completely loosely defined on the potential energy surface which does not have a barrier to recombination, and it becomes tightened as the energy increases above the reaction threshold.

In the diagnosis of the presacral epidermoid cyst, sonographic and magnetic resonance imaging findings may be helpful.

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We have comparatively investigated the photophysics of a series of bis-metal doubly N-confused hexaphyrins(1.1.1.1.1.1) using time-resolved fluorescence, femtosecond transient absorption, two-photon absorption measurements, and geometry-optimized ab initio calculations. Bis-Zn(II) and free-base doubly N-confused hexaphyrins exhibit well-resolved and red-shifted B- and Q-like absorption bands compared with porphyrins. Their allowed transitions are (pi,pi) transitions of the hexaphyrin ring, as confirmed by the HOMO and LUMO frontier orbitals based on ab initio calculations at the B3LYP/6-31G level. On the other hand, the absorption spectra of bis-Cu(II) and bis-Co(II) doubly N-confused hexaphyrins are relatively broad, presumably due to large couplings between the metal d-orbitals and pi-electrons of the hexaphyrin ring. Owing to these couplings, bis-Cu(II) and bis-Co(II) doubly N-confused hexaphyrins have much shorter excited-state lifetimes of 9.4 +/- 0.3 ps and 670 fs, respectively, than those (267 +/- 16 and 62.4 +/- 1.2 ps, respectively) of bis-Zn(II) and free-base doubly N-confused hexaphyrins. The two-photon absorption cross section (sigma(2)) values, which are believed to depend strongly on the ring planarity (pi-conjugation), are in line with the excited-state lifetime trends.

The reduction of cogging torque is the most important design objective for electric power steering (EPS) motors, because the rotation characteristics of the motor are directly transmitted to a driver. Therefore, a variety of optimal design methods are applied to reduce the cogging torque for EPS motors. However, the measured cogging torques of fabricated models are significantly greater than the finite-element analysis (FEA) results, because the additional harmonic components (AHCs) of the cogging torque are generated by manufacturing tolerances. The cogging torque generated by manufacturing tolerances can be divided into two components, which are generated by stator and rotor tolerances. In this study, AHCs, which cause cogging torque, are analysed by FEA by applying various tolerances to the analysis model, and harmonic analysis is also conducted. The relation of AHC generated from the stator and rotor is analysed by a rotor swapping test. Consequently, this study can be helpful to analyse the components of the cogging torque generated by manufacturing processes.

Color Doppler US may be helpful for differential diagnosis of tuberculous epididymitis and non-tuberculous epididymitis.