Flavonol Glycoside from Psorospermum androsaemifolium

A new flavonol glycoside, 3′‐(4′''‐(3′''',4′'''‐dihydroxyphenoxy)‐2′''‐hydroxyphenoxy)acanthophorin B ( 1a ) together with 3′‐(2′'',4′''‐dihydroxyphenoxy)acanthophorin B ( 1 ), acanthophorin B ( 2 ), vismiaquinone ( 3 ), rheochrysidin ( 3a ), lupeol acetate and fatty acid were isolated from the chloroform extract of the stem bark of Psorospermum androsaemifolium Baker (Clusiaceae). The structure of 1a was determined on the basis of detailed spectroscopic analysis and comparison with the literature. Compounds 1a and 3a showed moderate antimicrobial activity.     

Nectrianolins A,B, and C,new metabolites produced by endophytic fungus Nectria pseudotrichia 120-1NP

Two sesquiterpene-epoxycyclohexenone conjugates, nectrianolins A (1) and B (2), together with a sesquiterpene, nectrianolin C (3), were isolated from the brown rice culture of Nectria pseudotrichia 120-1NP, an endophytic fungus isolated from Gliricidia sepium. Their structures were determined on the basis of 1D-/2D-NMR spectroscopy and HRESIMS data analyses in combination with chemical means. Nectrianolins A–C (1–3) exhibited cytotoxic activity against both HL60 and HeLa cells.     

PIV and LDA measurements of secondary flow in a meandering channel for overbank flow

Secondary flow in a compound meandering channel with straight floodplain banks for overbank was investigated by a visualization method and velocity measurement using three-component laser Doppler anemometor (LDA). The secondary flow in a cross section was visualized by the neutral buoyant tracer method with a submergible video camera. Secondary flow vectors in a cross section were obtained by using PIV software with captured frames from video source through PC and also by LDA measurements. From the comparison of the PIV and LDA results, it is found that PIV data show good agreement in quality with LDA measurements when the secondary flow is strong and stable as shown in this paper.     

Synthesis and characterization of cis‐polybutadiene‐block‐syn‐polystyrene copolymers with a cyclopentadienyl titanium trichloride/modified methylaluminoxane catalyst

This article reports a practical method for preparing cis‐polybutadiene‐block‐syn‐polystyrene (cis‐PB‐b‐syn‐PS) copolymers with long crystallizable syndiotactic polystyrene (syn‐PS) segments chemically bonded with high cis‐1,4‐polybutadiene segments through the addition of styrene (ST) to a cis‐specific 1,3‐butadiene (BD) living catalyst composed of cyclopentadienyl titanium trichloride (CpTiCl₃) and modified methylaluminoxane (MMAO). The incorporation of ST into the living polybutadiene (PB) precursor remarkably depended on the polymerization temperature. A low temperature (?20 °C) suppressed the rate of ST incorporation, but a high temperature (50 °C) tended to decompose the livingness of the active species and enhance the rate of the aspecific ST polymerization initiated by MMAO. Consequently, temperatures of 0–25 °C seemed to be best for this copolymerization system. Because of the absence of ST livingness, the final products contained not only the block copolymer but also the homopolymers. Attempts to isolate the block copolymer were carried out with common solvent fractionation techniques, but the results were not sufficient. Cross‐fractionation chromatography was, therefore, used for the isolation of the cis‐PB‐b‐syn‐PS copolymer. The presence of long syn‐PS segments was confirmed by the observation of a strong endothermic peak at 260 °C in the differential scanning calorimetry curve. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2698–2704, 2004     

Copolymerization of 3‐buten‐1‐ol and propylene with an isospecific zirconocene/methylaluminoxane catalyst

The copolymerization of propylene and 3‐buten‐1‐ol protected with alkylaluminum [trimethylaluminum (TMA) or triisobutylaluminum] was conducted with an isospecific zirconocene catalyst [rac‐dimethylsilylbis(1‐indenyl)zirconium dichloride], combined with methylaluminoxane as a cocatalyst, in the presence of additional TMA or H₂ as the chain‐transfer reagent if necessary. The results indicated that end‐hydroxylated polypropylene was obtained in the presence of the chain‐transfer reagents because of the formation of dormant species after the insertion of the 3‐buten‐1‐ol‐based monomer followed by chain‐transfer reactions. The selectivity of the chain‐transfer reactions was influenced by the alkylaluminum protecting the comonomer and the catalyst structure. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5600–5607, 2004     

Synthesis of highly thermostable norbornene‐isoprene‐1‐octene terpolymer with titanium catalyst

Terpolymerization of norbornene (NB), isoprene (IP), and 1‐octene was achieved by using fluorenylamido‐ligated titanium catalyst, which showed very high activity for the copolymerization of NB and various α‐olefins. The content of IP in the terpolymer was controlled by the feed ratio and reaction temperature up to 7 mol %. The incorporated IP was mainly inserted in 1,4‐addition. The polymer was dissolved into common solvents such as toluene and chloroform, which enabled the preparation of a transparent film by solution casting process. The degradation temperature of the terpolymer was comparable with other cyclic olefin copolymers and the glass transition temperature (T_g) was higher than that of NB‐1‐octene copolymer with almost the same NB content. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2136–2140     

A flow-through cell for use with an enzyme-modified field effect transistor without polymeric encapsulation and wire bonding

A new type of flow-through cell for an enzyme-modified field effect transistor (FET) is described. The cell makes it possible to use a FET without polymeric encapsulation and wire bonding. Electrical evaluation of a FET used with the flow cell demonstrates that the flow cell has no practical problems causing sensor malfunctions. The noise and drift levels of tbe FET sensor with the flow cell are shown to be similar to those of an epoxy-encapsulated FET sensor. The application of the flow cell with a urease-modified FET is described. Useful responses are obtained for 0.25–50 mg l^?1 urea with relative standard deviations of <3%.