Two New Daphniphyllum Alkaloids from Daphniphyllum calycinum

Two new daphniphyllum alkaloids named 2‐hydroxyyunnandaphnine D ( 1 ) and methyl 7‐hydroxyhomodaphniphyllate ( 2 ), together with eight known alkaloids, daphnioldhanin D, calyciphylline F, calyciphylline B, deoxycalyciphylline B, daphnicyclidin H, macropodumine C, 9,10‐epoxycalycine A, and yunnandaphnine A, were isolated from the stems and leaves of Daphniphyllum calycinum. Their structures and relative configurations were established on the basis of spectral evidence (including 2D‐NMR) and subsequently confirmed by a single‐crystal X‐ray crystallographic diffraction analysis.     

Theoretical mechanisms of the superoxide radical anion catalyzed by the copper‐zinc superoxide dismutase

The disproportionation of superoxide radical anions catalyzed by copper‐zinc superoxide dismutase was investigated in detail using density functional theory. The structures of each stationary point and the transition states were located so that the reaction pathways were determined. The results indicate that the reactions proceed by two steps both for the oxidized process of superoxide radical anion and the reduced one. The rate for the determining step of the reaction (2) is in very good agreement with the experimental value. The solvation effect on the reaction was also discussed. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Ordered long‐helical conformation of isotactic polypropylene obtained in constrained environment of nanoclay

Special crystallization event of isotactic polypropylene (iPP) in a constrained environment, a layered clay network, was followed by in situ Fourier transform infrared (FTIR) spectroscopy during the cooling process. Before occurrence of nucleation/crystallization, a conformationally ordered phase, which consists of significant amounts of long 3₁ helices with 14 monomeric units, has been identified for the first time. More importantly, it was found that the long‐ordering helices could play a more important role than short ones for the confined crystallization. It could be tentatively explained as due to the existence of constrained regions in the proximity of the nanoclay platelets or tactoids and the heterogeneous nucleation capability of the surface of nanoclay. Copyright © 2011 John Wiley & Sons, Ltd.     

Air‐tolerantly surface‐initiated AGET ATRP mediated by iron catalyst from silica nanoparticles

Well‐defined polymer‐nanoparticle hybrids were prepared by a newly reported method: atom transfer radical polymerization using activators generated by electron transfer (AGET ATRP) mediated by iron catalyst. The kinetics of the surface‐initiated AGET ATRP of methyl methacrylate from the silica nanoparticles, which was mediated by FeCl₃/triphenylphosphine as a catalyst complex, ascorbic acid as a reducing agent, N,N‐dimethylformamide as the solvent in the presence of a “sacrificial” (free) initiator, was studied. Both the free and grafted polymers were grown in a control manner. The chemical composition of the nanocomposites was characterized by Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and ¹H nuclear magnetic resonance spectroscopy. Thermogravimetric analysis was used to estimate the content of the grafted organic compound, and transmission electron micrographs was used to observe the core‐shell structure of the hybrid nanoparticles. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2006–2015, 2010     

Structure determination of selaginellins G and H from Selaginella pulvinata by NMR spectroscopy

Selaginellins G ( 1 ) and H ( 2 ), two new selaginellin derivatives, were isolated from the whole plant of Selaginella pulvinata. Their structures were elucidated, and complete assignments of the ¹H and ¹³C NMR spectroscopic data were achieved by 1D and 2D NMR experiments (HSQC, HMBC, COSY and ROESY). Compound 1 displayed good antifungal activity against Candida albicans with an IC₅₀ value of 5.3 µg/ml. Copyright © 2010 John Wiley & Sons, Ltd.     

Perovskite-type oxide films combined with gratings for reduction of material consumption and improvement of thermochromism property

Combination of thermochromism of perovskite-type materials and gratings can result in some interesting variations of the spectral properties of structured surfaces. This paper aims at investigating thermal absorptive/radiative characteristics of structured thermochromic material La_0.825Sr_0.175MnO₃ (LSMO) with metallic and/or dielectric gratings. Numerical computation is conducted to obtain the distribution of the spectral absorptance of such structured surfaces with different structural parameters. The directional and temperature dependence of absorptance are also analyzed. The results reveal that compared with bulk LSMO material, the structured surface of LSMO achieves an improved thermochromic performance and much thinner layer of a structured LSMO film by combining the film with one-dimensional Al and SiO₂ gratings. Therefore, the other advantage of such structured surface is that the reduction of material consumption and weight is achieved due to the smaller LSMO layer thickness, which may be vital for thermal management of space vehicles.     

Copper‐catalyzed one‐pot synthesis of propargylamines via C?H activation in PEG

An efficient and convenient three‐component A³ coupling reaction of aldehyde, amine and alkyne via C? H activation with CuI alone as the catalyst in PEG is developed, providing a wide range of propargylamines with yields ranging from moderate to excellent. Additionally, the catalyst system was recovered and reused several times without evident loss in activity. Copyright © 2010 John Wiley & Sons, Ltd.     

Vector meson rescattering effect in understanding the threshold enhancement observed in J/ψ→γp(p)

We propose one possible mechanism,i.e.,the vector meson(VV)rescattering effects,to interpret the near threshold narrow enhancement observed in J/ψ→γp(p).The estimate indicates that these effects can give sizeable contributions to this channel,and a destructive interference between different rescattering amplitudes is required to reproduce the line shape of the data.     

Two New Steroidal Saponins from Diuranthera inarticulata

There are only three species in the genus Diuranthera (Liliaceae), which is endemic in the southwest of China1. Four steroidal saponins, diuranthosides A-C and chloromalo-side A were isolated from the fresh roots of D. major. This paper deals with the structure elucidation of two new steroidal saponins, diuranthosides D and E, which were isolated from the methanolic extract of whole plant of D. inarticulata Wang et K. Y. Lang.Diuranthoside D (1), [(]-38 (c 0.08, pyridine), afforded galac…