STRUCTURAL ELUCIDATION OF THE 8-METHOXYPSORALEN OXIDIZED PRODUCT THAT INHIBITS THE CHEMOTACTIC ACTIVITY OF POLYMORPHONUCLEAR NEUTROPHILS TOWARD ANAPHYLATOXIN C5a

The chemical structure of the 8-methoxypsoralen oxidized product that inhibits the chemotactic activity of anaphylatoxin C5a was determined to be 2,3-dihydro-2,9-dimethoxy-3-hydroxy-7-oxo-7H-furo[3,2-g] [1]benzopyran. Its minimal concentration required to obtain the maximum inhibition of C5a des Arg (1 x 10(-8) M) chemotactic activity is 2.5 x 10(-8) M. Bioactivity of this substance was maintained for 2 weeks, stored in a dark room at room temperature under aerobic conditions. There is a possibility that this substance may be useful in the treatment of immune complex diseases.     

Prompt chemoenzymatic synthesis of diverse complex-type oligosaccharides and its application to the solid-phase synthesis of a glycopeptide with Asn-linked sialyl-undeca- and asialo-nonasaccharides

We describe herein the preparation of 24 pure asparagine-linked oligosaccharides (Asn-oligosaccharides) from asparagine-linked biantennary complex-type sialylundecasaccharide [(NeuAc-alpha-2,6-Gal-beta-1,4-GlcNAc-beta-1,2-Man-alpha-1,6/1,3-)(2)-Man-beta-1,4-GlcNAc-beta-1,4-GlcNAc-beta-1-asparagine, 2] obtained from egg yolk. Our synthetic strategy aimed at adapting branch specific exo-glycosidases digestion (beta-D-galactosidase, N-acetyl-beta-D-glucosaminidase and alpha-D-mannosidase) of the individual asialo-branch after preparation of monosialyloligosaccharides obtained from 2 by acid hydrolysis of NeuAc. In order to perform branch specific exo-glycosidase digestion, isolation of pure monosialyloligosaccharides obtained was essential. However, isolation of two kinds of monosialyloligosaccharides are difficult by HPLC due to their highly hydrophilic nature. Therefore, we examined chemical protection with hydrophobic protecting (Fmoc and benzyl) groups. These chemical protection enabled us to separate the monosialyloligosaccharides by use of a HPLC column (ODS) on synthetic scales. Using these pure monosialiloligosaccharides enable us to obtain 24 Asn-linked oligosaccharides (100 mg scale) within a few weeks by branch specific exo-glycosidase digestions (alpha-D-neuraminidase, beta-D-galactosidase, N-acetyl-beta-D-glucosaminidase and alpha-D-mannosidase). In addition, solid-phase synthesis of glycopeptide having Asn-linked sialyl-undeca- and asialo-nonasaccharides thus obtained, was also performed on an acid labile HMPA-PEGA resin.     

Island dynamics in the large-helical-device plasmas

In the Large Helical Device plasma discharges, the size of an externally imposed island with mode number ( n/m = 1/1) decreases substantially when the plasma is collisionless ( nu(*)< approximately 1) and the beta is finite ( > approximately 0.1%) at the island location. For the collisional plasmas with finite beta, on the other hand, the size of the island increases. However, there is a threshold in terms of the vacuum island size below which the island enlargement is not seen.     

Strong enhancement of extremely energetic proton production in central heavy ion collisions at intermediate energy

The energetic proton emission has been investigated as a function of the reaction centrality for the system (58)Ni + (58)Ni at 30A MeV. Extremely energetic protons (E(NN)(p) > or = 130 MeV) were measured and their multiplicity is found to increase almost quadratically with the number of participant nucleons, thus indicating the onset of a mechanism beyond one- and two-body dynamics.     

Core-level and valence-band characteristics of carbon nitride films with high nitrogen content

Carbon nitride films with high nitrogen content were prepared by reactive pulsed-laser deposition at nitrogen partial pressures varying from 0.1 to 20.0 Torr. It was found that the nitrogen content in the films first increases with increase of the nitrogen pressure, reaches a maximum of 46 at. % at 5.0 Torr, and then decreases to 37 at. % at 20.0 Torr. The almost pure carbon nitride films were systematically characterized by using X-ray photoelectron spectroscopy (XPS) concerning the core-level and valence-band structures. Some fingerprint information, which shows the role of nitrogen in controlling the electronic structure of carbon nitride films, was found based on the XPS studies. With enhancing the nitrogen incorporation, both the binding energy and the peak intensity of the core-level and the valence-band spectra vary systematically as a function of nitrogen content in the films. Received: 26 June 2000 / Accepted: 26 June 2000 / Published online: 20 September 2000     

Synthesis of methylcellulose model copolymers with heterogeneous distribution and their solution properties

In order to elucidate the characteristic features of commercial methylcellulose precisely, O-methylcellulose model copolymers consisting of 2,3,6-tri-O-methylanhydroglucose unit (236MeAGU) and 2-O-methylanhydroglucose unit (2MeAGU) with various composition ratios were synthesized via cationic ring-opening copolymerization of the corresponding glucose orthoester derivatives, subsequent removal of pivaloyl and allyl groups, and methylation. The structure of the obtained copolymers was confirmed by ¹H-, ¹³C-NMR, and FT-IR. Temperature-dependent turbidity measurement verified their thermoresponsive behavior in aqueous solution. The lower critical solution temperature was tuned from 63 to 45 °C above 47 mol-% 236MeAGU content. The hydrophobicity along the cellulose chain was dominant to determine their physical properties. However, the aqueous properties of the MC model copolymers were strongly affected by the slight difference of the composition ratio. The present method would provide further details of the structure–property relationship of O-methylcellulose.     

Measurements of thermally stratified pipe flow using image-processing techniques

The cross-correlation technique and Laser Induced Fluorescence (LIF) have been adopted to measure the time-dependent and two-dimensional velocity and temperature fields of a stably thermal-stratified pipe flow. One thousand instantaneous and simultaneous velocity and temperature maps were obtained at overall Richardson numberRi = 0 and 2.5, from which two-dimensional vorticity, Reynolds stress and turbulent heat flux vector were evaluated. The quasi-periodic inclined vortices (which connected to the crest) were revealed from successive instantaneous maps and temporal variation of vorticity and temperature. It has been recognized that these vortices are associated with the crest and valley in the roll-up motion.List of symbols A Fraction of the available light collected - C Concentration of fluorescence - D Pipe diameter - I Fluorescence intensity - L Sampling length along the incident beam - I ₀ Intensity of an excitation beam - I _c (T) Calibration curve between temperature and fluorescence intensity - I _ref Reference intensity of fluorescence radiation - Re _b Reynolds number based on bulk velocity,U _b D/v - Ri Overall Richardson number based on velocity difference,gDT/U ² - t Time - t Time interval between the reference and corresponding matrix - T Temperature - T ₁,T ₂ Temperature of lower and upper layer - T ^* Normalized temperature, (T–T ₁)/T - T _c (I) Inverse function of temperature as a function ofI _c - T _ref Reference temperature - T Temperature difference between upper and lower flow,T ₂ –T ₁ - U ₁ Velocity of lower stream - U ₂ Velocity of upper stream - U _b Bulk velocity - U _c Streamwise mean velocity atY/D=0 - U Streamwise velocity difference between upper and lower flow,U ₁–U ₂ - u, v, T Fluctuating component ofU, V, T - U, V Velocity component of X, Y direction - X Streamwise distance from the splitter plate - Y Transverse distance from the centerline of the pipe - Z Spanwise distance from the centerline of the pipe - Quantum yield - Absorptivity - vorticity calculated from a circulation - Kinematic viscosity - circulation     

Element distributions for the reactions32S+100Mo,32S+93Nb and28Si+93Nb near the coulomb barrier

The element distributions for the reactions³²S+¹⁰⁰Mo,³²S+⁹³Nb, and²⁸Si+⁹³Nb have been measured atE/B～1.4. The correlations between the first moment of the measured distributions and TKEL are consistent with the predictions of the liquid drop potential energy surfaces showing the charge equilibration of the dinuclear systems. The measured second moments are compared with a recent systematics.     

Synthesis and central nervous system stimulant activity of 5,8-methanoquinazolines fused with 1,2,4-triazole,tetrazoleand 1,2,4-triazine

5,8-Methanoquinazolines fused with 1,2,4-triazole 4–5 , tetrazole 6 , and 1,2,4-triazine 8 were prepared starting from 2-hydrazino-5,8-methanoquinazoline 3 . Compound 3 and 6 showed the most potent central nervous system (CNS) stimulant activities.     

High field magnetization of the Laves phase compounds M(Co1−xAlx)2 (M = Y, Lu)

Magnetization measurements have been carried out on the Laves phase compounds M(Co_1−xAl_x)₂(M = Y, Lu) up to 42 T. Sharp metamagnetic transitions with small hysteresis are found in Y(Co_1−xAl_x)₂, while broad transitions with large hysteresis are found in Lu(Co_1−xAl_x)₂. The results suggest that the former compounds are magnetically homogeneous but the latter inhomogenous.