Studies on lens-aldose-reductase inhibitor in medicinal plants. II. Active constituents of Monochasma savatierii Franch. et Maxim

The 70% acetone extract of Monochasma savatierii FRANCH. et MAXIM. showed very strong inhibition of rabbit lens aldose reductase (AR). From the active fraction, five iridoid glucosides along with the two phenolic glycosides, acteoside and dehydroacteoside, have been isolated. Among them, acteoside showed the highest activity, being about 2.5 times more potent than baicalein, a known natural inhibitor of AR (IC50 = 9.8 x 10(-7) M). Demethylmussaenoside and 7-O-acetyl-8-epi-loganic acid, which are iridoid glucosides, had weak inhibitory activity.     

Use of functional microgels with vinyl groups to accelerate photopolymerization reaction

Three types of functional microgels with vinyl groups on their surface were prepared. For the first type, the counter anion from clorin was exchanged with β-methacryloylethyl sulfonic acid, styrene sulfonic acid or allyl sulfonic acid in a microgel with ammonium anions. For the second and third types, a quaternization with N,N-dimethylaminoethyl methacrylate of 3-chloro-2-hydroxypropyl methacrylate in the presence of microgel particles was prepared by emulsion copolymerization of styrene, chloromethylstyrene or N,N-dimethylamino-methylbenzene, and divinylbenzene. The resulting samples show good dispersibility in organic solvents without an emulsifier. A functional microgel-based photopolymer combined with an acrylate monomer and ultraviolet (UV) or visible (VIS) light-absorbing photoinitiators provides oleophilic images when exposed to UV or VIS light and developed in tap water. This photopolymer has a higher sensitivity than those of photopolymers based on microgels with an analogous composition but without vinyl groups. Photopolymers pepared by using functional microgels with a methacryloyl group exhibited a higher rate of polymerization (R_p) than that of photopolymers based on microgels without a vinyl group. The R_p of photopolymers prepared by using a functional microgel with either an allyl group or vinylphenyl group was nearly equal to that of photopolymers based on microgels with ammonium ions. Their high sensitivities are attributed to the rapid photopolymerization in the methacryloyl group. To determine how the photoreaction mechanism enhances sensitivity, the photoreaction products were investigated using a model photopolymerization system. It was found that the gelation reactions enhancing sensitivity are predominantly the polymerization and crosslinking ones when a microgel with the methacryloyl group is used, and the graft copolymerization with acrylate monomers when a microgel with either the allyl group or vinylphenyl group is used.     

Synthesis of 12-acetoxy-1, 3-dodecadiene,an insect sex pheromone of the red bollworm moth,from a butadiene telomer

8-Phenoxy-1, 6-octadiene (1) formed by the Pd-catalyzed telomerization of butadiene with phonol was converted to 8-phenoxy-6-octen-1-ol (3). The alcohol 3 was converted to 8-iodo-1-phenoxy-2-octene (5). The Grignard reagent 7 prepared from 4-chloro 1-butyl tetrahydropranyl ether was coupled with the iodide 5 by the catalysis of CuI and bipyridyl to give 12-phenoxy-10-dodecen-1-ol (9), which was converted to 12-acetoxy-1-phenoxy-2-dodecene (10). Finally, 12-acetoxy-1, 3-dodecadiene (11) was obtained by the palladium catalyzed elimination of phenol from phenoxyacetoxy-dodecene (10).     

Thermal and acid-catalyzed reaction of bifunctional vinyl ether urethane in nonionic and ionic polymer matrices

A bifunctional vinyl ether urethane derivative (BVU) was synthesized and characterzed. Photoresist systems consisting of BVU and a photoacid generator (PAG) along with various matrix polymers were prepared and the photoresist characteristics were evaluated. In the presence of BVU and a PAG, poly(methylmethacrylate-co-acrylic acid) and poly(methylmethacrylate) exhibited positive and negative tone behavior, respectively, where as poly(p-hydroxystyrene) showed both positive and negative working properties depending on the prebake temperature of the system. The depandence of the photoresist behaviors on these matrix polymers was studied. The mechanism of the thermal and photochemical reactions was revealed.     

13C-NMR study of crosslinking and long-chain branching in linear polyethylene induced by 60Co gamma ray irradiation at different temperatures

H-type crosslinking and Y-type long-chain branching have been examined for linear polyethylene samples irradiate at different temperatures with ⁶⁰Co gamma rays in vacuum by solution-state ¹³C-NMR spectroscopy. In this study, relatively low molecular weight samples were irradiated with doses less than a gel dose in both solid and molten states. Resonance lines associated with H-links and Y-branches have clearly been observed for each irradiated sample and their radiation yields significantly depend on the irradiation temperature and the morphology of the samples. In particular, the G-value for the production of Y-branches is higher than that for H-links at lower temperatures, while the latter is superior to the former at higher temperatures. This may be due to the decrease in the concentration of the primary radicals, which are formed by main-chain scissions and associated with the production of Y-branches, by the recombination with small fragments at higher temperatures. The radiation yields of methyl branches and double bonds are also briefly discussed.     

Photo- and radiation-induced degradation of vinyl polymers in solution. I. Oxidative degradation of poly(α-methylstyrene) initiated by photodecomposition of AIBN

The oxidative degradation of poly(α-methylstyrene) initiated by the photodecomposition of azobisisobutyronitrile was studied at 30°C in benzene solution. The progress of the reaction was followed by measuring the rate of chain scission of the polymer. It has been confirmed by GPC measurements that random scission of the polymer chain occurs in the present system. Chain scission did not occur in the absence of AIBN and oxygen. The rate was proportional to the initiation rate and independent of polymer concentration and oxygen pressure under these experimental conditions. Phenol was an effective inhibitor to this reaction. The mechanism of chain scission during oxidation is discussed, and a six-membered transition is proposed.     

Absolute photoionization cross sections with ultra-high energy resolution for Ar, Kr, Xe and N2 in inner-shell ionization regions

The high-resolution absolute photoionization cross sections for Ar, Kr, Xe and N₂ in the inner-shell ionization region have been measured using a multi-electrode ion chamber and monochromatized synchrotron radiation. The energy ranges of the incident photons for the target gases were as follows: Ar: 242–252 eV (2p Rydberg excitation), Kr: 1650–1770 eV (near the 2p ionization thresholds), Xe: 665–720 eV (near the 3d ionization thresholds) and 880–1010 eV (near the 3p ionization thresholds), N₂: 400–425 eV (N 1s excitation and ionization). It is the first time to measure the absolute ionization cross sections of Ar, Kr, Xe and N₂ over the present energy ranges with the energy resolution of over 10,000. The natural lifetime widths of , , and resonances for Ar, resonance for Xe, and resonance for N₂ have been obtained based on the cross sections determined. The ionization energies into the Ar⁺ (), Ar⁺ () and Xe⁺ () ionic states are also determined using the Rydberg formula.     

Reversing-pulse electric birefringence of multicomponent systems: the formulation and signal simulation for two axially symmetric components in equilibrium and the appearance of unusual signal patterns

This paper consists of two parts on reversing-pulse electric birefringence (RPEB) signal patterns. The first is the theoretical formulation of two axially symmetric models coexisting in equilibrium in solution. The present RPEB theory is based on the original Tinoco-Yamaoka theory with classical electric dipole moments, which was recently modified and extended by Yamaoka, Sasai, and Kohno to include various electric and optical parameters and most importantly the ion-fluctuation dipole moment (1/2) along the longitudinal direction of axially symmetric molecules. The theory contains the electric polarizability anisotropy Deltaalpha', which can be either positive or negative in relation to the shape of components. The overall signal can be expressed as the sum of the fractions of two components in proportions to the coefficient F(1) or F(2) (=1-F(1)). The second part is the simulation of theoretical RPEB curves for the two-component system with various sets of electric and hydrodynamic parameters for hypothetical but interesting cases. In consideration of the decay behavior, calculated decay curves were compared with experimentally conceivable signals, classifying them into three categories according to cases: F(1)>1, 0/ktDeltaalpha(') is the crucial factor that controls the pattern of RPEB signals. If q value of one component is positive and the other is negative, the simulated RPEB curves are characterized by three cases: q>0, q<-1, and -10 or q<-1, the resultant patterns are often encountered with experimental signals. If -1相似文献