New triterpenoid saponins from fruit specimens of Panax japonicus collected in Toyama prefecture and Hokkaido (2)

Four new dammarane-type triterpenoid saponins, chikusetsusaponin FT(1) (1), chikusetsusaponin FT(2) (2), chikusetsusaponin FT(3) (3), chikusetsusaponin FT(4) (4), and six known triterpenoid saponins, chikusetsusaponin FK(4) (8), chikusetsusaponin FK(5) (9), chikusetsusaponin FK(2) (10), chikusetsusaponin FK(3) (11), chikusetsusaponin LN(4) (12), and chikusetsusaponin IVa (14), were isolated from the fruits of Panax japonicus C. A. MEYER, collected in Toyama prefecture, Japan, and five new dammarane-type triterpenoid saponins, chikusetsusaponin FT(1) (1), chikusetsusaponin FT(3) (3), chikusetsusaponin FT(4) (4), chikusetsusaponin FH(1) (5), chikusetsusaponin FH(2) (6), and eight known triterpenoid saponins, ginsenoside Re (7), chikusetsusaponin FK(5) (9), chikusetsusaponin FK(2) (10), chikusetsusaponin FK(3) (11), chikusetsusaponin LN(4) (12), 28-desglucosylchikusetsusaponin IVa (13), chikusetsusaponin IVa (14), and chikusetsusaponin V (15), were isolated from the fruits of P. japonicus C. A. MEYER, collected in Hokkaido, Japan. The structures of new chikusetsusaponins were elucidated on the basis of chemical and physicochemical evidences.     

Time-resolved fluorimetry with a sub-nanosecond dye laser source for the determination of polynuclear aromatic hydrocarbons after separation by high-performance liquid chromatography

A sub-nanosecond tunable dye laser pumped by a transversely-excited atmosphericpressure nitrogen laser is combined with a time-resolved fluorescence detection system, consisting of a microchannel plate photomultiplier, a sampling oscilloscope, and microcomputer data-processing equipment. This system has a time resolution of 1.4 ns, and is used for determinations of traces of polynuclear aromatic hydrocarbons, in conjunction with high-performance liquid chromatography. The advantages of time-resolved detection are illustrated. Benzo(a)pyrene is determined in samples obtained from airborne particulates.     

Determination of uranium at ultratrace levels by time-resolved laser fluorimetry

Uranium at ultratrace levels in the pelleted cake from a NaF/Na₂CO₃/K₂CO₃ (10:45:45) fusion is determined by laser fluorimetry. Light scattering and fluorescence from impurities are greatly reduced by time-resolved fluorimetry. The optimum excitation wavelength is shown to be 360 nm from the signal-to-background ratio spectrum; emission is measured at 555 nm. The detection limit is 9 ng kg^?1 for a standard uranium sample. Relative standard deviations in the determination of ca. 50 ng kg^?1 uranium in silica samples are about 10%.     

Synthetic macrocyclic ligands. IV. Lithium ion-characteristic coloration of a “crowned” dinitrophenylazophenol

A “crowned” dinitrophenylazophenol shows a characteristic coloration only with lithium ion of alkali metal ions, as if an indicator.     

Allylic alcohols formation by oxidation of allylic phenyl tellurides. A possible [2,3] sigmatropic rearrangement of allylic telluroxides

Treatment of cinnamyl, 3-methyl-2-butenyl, and 2-cyclohexenyl phenyl tellurides with an oxidizing agent such as H₂O₂, NaIO₄ or t-BuOOH at room temperature under nitrogen affords 1-phenyl-2-propenol, 2-methyl-3-butene-2-ol, and 2-cyclohexenol as a sole or main product respectively in a high yield. The formation of these allylic alcohols can be best explained by assuming a [2,3]-sigmatropic rearrangement of the intermediate allylic telluroxides. These tellurides also react with oxygen, the formation of α.β-unsaturated carbonyl compounds being much increased in this oxidation.     

Lens Design: Global Optimization with Escape Function

The technique of using the ‘escape function’ for global optimization in lens design is described. This includes how to identify two solutions as independent; the threshold value for this criterion can be chosen to determine how to explore local solutions—rough or fine. Choice of appropriate values for two parameters in the escape function is most important, since this will affect the efficiency of the automatic global optimization process. There are two problems, i.e. giving default values at the beginning of the design, and determining a default rule to change them when the escape is unsuccessful. The latter was solved by assuming a ‘saddle path’ as the best route to escape. An exact solution for the former was not found, but a hint for finding a second best solution is shown based on the statistical study of local minima.     

Energy decomposition analysis of borane monoammoniate: origin of the rotational barrier to nonrigid rotation

Rotational barrier for borane monoammoniate was studied at the Hartree-Fock level using several Gaussian basis sets. Rotational barrier to nonrigid rotation was estimated to be 1.85 kcal/mol using the 6–31G^☆ basis set. Furthermore, energy decomposition of the barrier was performed. For the rigid rotation, the origin of the rotational barrier was dominantly due to the exchange repulsion term. On the contrary, for the nonrigid rotation, the electrostatic term was the most important contributor, and the exchange repulsion played rather minimal role. The nonrigid rotation is also explained as the two-step process of the rigid rotation and the geometry relaxation.     

Preparation of large macrocyclic tetra-amines consisting of a methylene backbone and a cyclophane type skeleton

Efficient synthetic routes to 1,10,19,28-tetraazacyclohexatriacontane, a 36-membered ring compound with a methylene backbone, and bis(N,N-octamethylene-4,4′-diaminodiphenylmethane), a 38-membered tetra-amine with a cyclophane skeleton, have been developed via reduction of tetralactam and via a double condensation reaction, respectively. Overall yields are 51% with 5 steps for the former, and 46% with 6 steps for the latter, while the corresponding 2 + 2 cyclization gave the cyclic compounds in poor yields, 9% and 4%, respectively, for the 36-membered tetra-aza ring and for the 38-membered cyclophane derivative.