CCSD calculations on C(14), C(18), and C(22) carbon clusters

The structure and energetics of the ring isomers of C(4n+2) (n=3-5) carbon clusters were studied by using coupled-cluster singles and doubles excitation theory to overcome the vast differences existing in the literature. The results obtained in the present study clearly indicate that C(14), C(18), and C(22) carbon rings have bond-length and bond-angle alternated acetylenic minimum energy structures. Contrarily, density functional theory calculations were unable to predict these acetylenic-type structures and they ended up with the cumulenic structures. It is found from the coupled-cluster studies that the lowest-energy ring isomer for the first two members of C(4n+2) series is a bond-angle alternated cumulenic D((2n+1)h) symmetry structure while the same for the remaining members is a bond-length and bond-angle alternated C((2n+1)h) symmetry structure. In C(4n+2) carbon rings, Peierls-type distortion, transformation from bond-angle alternated to bond-length alternated minimum energy structures, occurs at C(14) carbon ring.     

Novel lanostane and rearranged lanostane-type triterpenoids from Abies sachalinensis - II -

In the previous work we reported five A-seco-rearranged lanostane triterpenoids as antibacterial constituents from the ethyl acetate soluble fraction of Abies sachalinensei leaves. In further study on the isolation of constituents from the ethyl acetate soluble fraction, two new rearranged lanostane and lanostane-type triterpenoids (3, 4) and three reported compound (1, 2, 5) were isolated. The structures of new compound 3 and 4 were determined to be 3,4-seco-4(28),6,8(14),24-mariesatetraen-26,23-olide-23-hydroxy-3-oic acid and 3,4-seco-4(28),7,24-lanostatrien-26,23-olide-23-hydroxy-3-oic acid, respectively, by spectral studies on HR-MS, (1)H-NMR, (13)C-NMR, and 2D-NMR spectra. Compound 1 was identified with pindrolactone and its structure was revised as 7,14,22Z,24-mariesatetraen-26,23-olide-3alpha-ol. Structures of 2 and 5 were determined as 7,14,24-mariesatrien-26,23-olide-3alpha,23-diol and 3alpha-hydroxy-7,14,24E-mariesatrien-23-oxo-26-oic acid. Of these compounds, 2, 3 and 4 were obtained as lactol tautomer mixtures at gamma-lactone structures of side chains.     

One-port ring refractive index sensor with attached sub-ring

Optical Review - In this report, we propose a ring resonator with one port for surface normal input/output attached with another ring resonator. A resonance generated by one of the ring resonators...     

Benzonorcorrole NiII Complexes: Enhancement of Paratropic Ring Current and Singlet Diradical Character by Benzo‐Fusion

Fused benzene rings to antiaromatic compounds generally improve their stability but attenuate their antiaromaticity. The opposite case is now reported. Ni^II benzonorcorroles were synthesized and the effect of benzo‐fusion on the antiaromaticity was elucidated. The benzo‐fusion resulted in significant decrease of the HOMO–LUMO gaps and enhancement of the paratropic ring current effect. Furthermore, the introduction of the benzo groups induced singlet diradical character in the antiaromatic porphyrinoid.     

Comparison of Capillary and Skimmer Interfaces in Evolved Gas Analysis-Mass Spectrometry (EGA-MS) with Regard to Impurities in Ceramic Raw Materials

Capillary and skimmer interfaces in EGA-MS were compared by analysis of the carbon substances remaining in the hydrolysis products of aluminum alkoxides. Peaks with higher intensities were detected in the skimmer interface mode than those in the capillary interface mode. It was confirmed in particular that the skimmer interface is effective in increasing the sensitivity for species with higher mass, e.g. the evolved butyl group, as carbon substances remaining in the hydrolysis product of aluminum sec-butoxide. This revised version was published online in July 2006 with corrections to the Cover Date.     

Antitumor-promoting constituents from Chaenomeles sinensis KOEHNE and their activities in JB6 mouse epidermal cells

Primary screening of antitumor-promoting activity using soft agar colony assays with JB6 cells was employed to isolate 22 compounds from Chaenomeles sinensis KOEHNE. These compounds were lyoniresinol-2a-O-alpha-L-rhamnopyranoside (1), lyoniresinol-2a-O-beta-D-glucopyranoside (2), aviculin (3), betulinic acid (4), betulin (5), 3-O-(E)-p-coumaroylbetulin (6), 3-O-(E)-caffeoylbetulin (7), 3-O-(Z)-p-coumaroylbetulin (8), 3-O-(E)-caffeoyllupeol (9), alphitolic acid (10), sorbikortal II (11), tormentic acid (12), euscaphic acid (13), corosolic acid (14), maslinic acid (15), erythrodiol (16), 1-beta-D-glucopyranosyloxy-3,4,5-trimethoxybenzene (17), avicularin (18), 7-O-beta-D-glucopyranosylkaempferol (19), 5-O-beta-D-glucopyranosylgenistein (20), 7-O-beta-D-glucopyranosylgenistein (21), epicatechin (22), and beta-sitosterol (23) and were identified using spectral data such as MS, (1)H- and (13)C-NMR. Compound 1, having a rhamnosyl group, showed greater activity than 2, having a glucosyl group, and 3, which was a bis-demethoxy derivative of 1. Betulinic acid (4), having a C-28 carboxyl group, 3-O-(E)-caffeoylbetulin (7), and tormentic acid (12) showed more potent activity than betulin (5), which has a C-28 hydroxymethyl group.