Nine new secoiridoid glucosides from Jasminum nudiflorum

Phytochemical study of the leaves of Jasminum nudiflorum has led to the isolation of nine new secoiridoid glucosides, jasnudiflosides F-L (1-7), nudifloside D (8) and isooleoacteoside (9). The structures of these compounds were elucidated on the basis of chemical and spectroscopic evidence.     

Control of light pulse propagation with only a few cold atoms in a high-finesse microcavity

Propagation of a light pulse through a high-Q optical microcavity containing a few cold atoms (N<10) in its cavity mode is investigated experimentally. With less than ten cold rubidium atoms launched into an optical microcavity, up to 170 ns propagation lead time ("superluminal"), and 440 ns propagation delay time (subluminal) are observed. Comparison of the experimental data with numerical simulations as well as future experiments are discussed.     

Facile synthesis of chiral glycine using D-glucose as a chiral template

A facile synthetic method of chiral glycine and a new access to chiral acetic acid based on a concept of chirality transfer from glucose are described.     

An HPLC assay of hydroxyl radicals by the hydroxylation reaction of terephthalic acid

An HPLC assay for hydroxyl radicals is described. The hydroxyl radical was trapped by terephthalic acid (non-fluorescent), and 2-hydroxyl terephthalic acid (fluorescent) was quantitated by HPLC-fluorescence detection. At a terephthalic acid concentration of 4.25 mmol/L, the hydroxyl radical formed in the Fenton reaction was successfully assayed in the concentration range of hydrogen peroxide of 2.5-50 micro mol/L, where the concentration of Fe(II) was 50 micro mol/L. The fluorescence of 2-hydroxy terephthalate was stable at 24 h, and its detection limit by this method was 5 nmol/L (100 fmol).     

Mevashuntin, a novel metabolite produced by inhibition of the mevalonate pathway in Streptomyces prunicolor

Inhibition of the mevalonate pathway by an HMG-CoA reductase inhibitor, mevalotin, in Streptomyces prunicolor possessing both mevalonate and MEP pathways resulted in the production of a new metabolite mevashuntin that consisted of conjugated thiazolone and pyranonaphthoquinone moieties.     

Bending properties and cell wall structure of alkali-treated wood

Bending tests and X-ray diffraction studies were conducted on oven-dried wood samples (Picea jezoensis Carr.) treated with various concentrations of aqueous NaOH solution to investigate the influence of alkali treatment on the longitudinal contraction, bending properties, and cellulose structure. The length of the wood samples decreased and the density increased at NaOH concentrations greater than 10%. The Young’s modulus and the specific Young’s modulus decreased and the strain at yield increased for the same concentration range. However, the stress at yield was almost constant for all concentration ranges. X-ray diffraction analysis showed that lattice transformation from cellulose I to cellulose II did not occur during alkali treatment and the crystallinity index decreased at NaOH concentrations greater than 10%. The crystallinity index was linearly correlated with the changes in longitudinal contraction and the bending properties, which indicates that the increase in the proportion of amorphous components of the cellulose influences the longitudinal contraction and the bending properties of wood samples during alkali treatment.     

Structure and morphology of the aliphatic polyester poly(δ‐valerolactone) in solution‐grown,chain‐folded lamellar crystals

Poly(δ‐valerolactone) (PVL) crystals in the form of chain‐folded lamellae were prepared by isothermal crystallization from a 2‐methylbutane‐2‐ol solution. Wide‐angle and small‐angle X‐ray diffraction data, obtained from PVL lamellae sedimented to form oriented mats, were supplemented with morphological and structural data from electron microscopy, both imaging and diffraction. The diffraction signals index on an orthorhombic unit cell with the parameters a = 0.747 ± 0.002 nm, b = 0.502 ± 0.002 nm, and c (chain axis) = 0.742 ± 0.002 nm. Similar unit cell parameters were obtained from crystals grown from 1‐octanol and also from drawn melt‐pressed films. The evidence supports a model containing two antiparallel chain segments in the unit cell. The c value of 0.742 nm is appropriate for an all‐trans or onefold helical backbone conformation for the straight stems. Possible slight perturbations at the ester units from the all‐trans backbone conformation are discussed. Computerized modeling was used to optimize the adjacent‐reentry folded structure. The setting angles, with respect to the a axis, are ±58° for the corner and center chains. The lamellae are 7.26 ± 0.05 nm thick, and the chains run orthogonal to the lamellar surface. The chains fold in the diagonal (110) and (11¯0) planes in an alternating fashion. The X‐ray diffraction data suggest that a proportion of adjacent paired antiparallel entities, or hairpin units, are c‐axis‐sheared, and a relationship to the results obtained from drawn films is discussed. A brief comparison is also made with related polymer structures. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2622–2634, 2001     

A basic study on the sound field analysis of periodic structures by boundary integral equation method

This study deals with the development of the approximate method to analyze the sound field around equally spaced finite obstacles, using the periodic boundary condition. First, on the assumption that the equally spaced finite obstacles are the periodically arranged obstacles, the sound field is analyzed by boundary integral equation method with a Green’s function which satisfies the periodic boundary condition. Furthermore, by comparing these results and the exact solution by using the fundamental solution as Green’s function, the validity of the approximate method is also investigated. Next, in order to evaluate the applicability of the approximate method, the simple formula using some parameters, i.e., the frequency, the period, and the number of obstacles, etc., is proposed. The results of the sound field analysis applied the formula are presented.     

On the equivalent inclusion method and impotent eigenstrains

The equivalency equations and the nature of the solution are investigated when an inhomogeneity under applied stresses is simulated by an inclusion with eigenstrains. The equivalency equations by which the equivalent eigenstrain is obtained becomes singular when the inhomogeneity is void and the applied stress has a form of polynomials of coordinates of degree one. The solutions of the system of the equivalency equations are not uniquely determined. Explicit expressions are given for the impotent eigenstrains which do not generate any stress field throughout a material.This research was supported by the U.S. Army Research Office under Grant No. DAAG 29-77-G-0042 to Northwestern University.On leave of absence of Meiji University, Tokyo.