Tricalysiosides P-U: Ent-kaurane glucosides and a labdane glucoside from leaves of Tricalysia dubia OHWI

Further extensive isolation work on the 1-BuOH-soluble fraction of a MeOH extract of Tricalysia dubia afforded five new ent-kaurane glucosides (4-8) and one new labdane glucoside (9), together with a known megastigmane glucoside, sammangaoside B (1), and monoterpene glucosides (2, 3). The structures of the new compounds were elucidated by analyses of one- and two-dimensional NMR spectroscopic data. The absolute configuration of the 9-position of sammangaoside B was revised to S and its total stereochemistry was established by the modified Mosher's method.     

Hyper-Raman scattering enhanced by anisotropic dimer plasmons on artificial nanostructures

Silver nanodimers with a small gap of a few nanometers aligned on glass substrates were used to enhance hyper-Raman scattering of crystal violet dye molecules. When localized surface plasmon of the dimer array was resonantly excited along the interparticle axis, hyper-Raman intensity was significantly enhanced. Moreover, the spectral appearance was slightly different between the two excitation polarizations, suggesting a possibility of two resonance contributions at one-photon and two-photon energies. Since the plasmonic property of dimer arrays can be controlled by the dimer geometry, the dimer arrays are expected to be well-defined substrates for surface-enhanced hyper-Raman spectroscopy.     

Rheological and DSC studies of mixtures of gellan gum and konjac glucomannan

The interaction between gellan gum (GELL) and konjac glucomannan (KGM) with and without sodium chloride, potassium chloride, calcium chloride and magnesium chloride has been monitored using mechanical spectroscopy and differential scanning calorimetry (DSC). The rheological results indicated that the synergism occurred at sufficient low temperatures where individual helices of GELL molecules were sufficiently aggregated. With progressive addition of monovalent cations, storage shear modulus G' and loss shear modulus G” for mixtures gradually increased, and not only the helix-coil transition temperature of GELL molecules in mixtures but also the sol-gel transition temperature for mixtures shifted to higher temperatures with increasing concentration of salts. Moreover, in the presence of sufficient monovalent cations, mixtures formed an elastic gel with large thermal hysteresis. In the presence of divalent cations, the synergistic interaction was promoted up to a certain concentration, however, with more progressive addition of divalent cations, the main structure formed by aggregates of GELL helices would be smaller, so that mixtures could not form a gel in the presence of excessive divalent cations. DSC results indicated that the intermolecular binding complexes between GELL and KGM molecules would not occur, but KGM markedly influenced the disorder-order transition of GELL molecules. We have suggested that KGM was attached to the surface of large aggregates of GELL helices, and since cations promote GELL self-aggregation by a screening effect, the synergistic interaction between GELL and KGM was promoted with increasing concentration of salts. However, excessive divalent cations formed various aggregates of GELL helices with different thermal stabilities, so that the phase-separation in GELL/KGM mixtures was promoted in the presence of excessive divalent cations.     

Synthesis of nickel nanoparticles supported on hollow samaria-doped ceria particles via the solution-spray plasma technique: Anode catalysts for SOFCs

Aiming at SOFC anode applications, we have synthesized nanometer-sized nickel catalysts supported on hollow spherical particles of samaria-doped ceria (Ni/SDC) by spraying a mixed solution of nickel, samarium, and cerium nitrates into an atmospheric pressure plasma. The as-prepared particles consisted of SDC (average diameter d_SDC = ca. 0.8 µm) and uniformly dispersed nanometer-sized NiO particles. When reduced in H₂ at 800 °C or 1000 °C, Ni nanoparticles (average diameter d_Ni = 34 nm) were found to be embedded uniformly into the SDC surface.     

Isotope effects in the dissociation of the B 1A1 state of SiH2, SiHD, and SiD2 using three-dimensional wave packet propagation

Dissociations after the A 1B1-->B 1A1 photoexcitation of SiH2, SiHD, and SiD2 were studied to investigate excited-state dynamics and effects of the initial vibrational state. The cross section (sigma) for the photodissociation relative to SiH2(B)-->Si(1D)+H2 and the rovibrational population of the H2 fragment were computed using the wave packet propagation technique based on the three-dimensional potential energy surfaces (PESs) of the A and B electronic states and the transition dipole surfaces, which were reported in our previous paper [J. Chem. Phys. 122, 144307 (2005)]. The photodissociation spectrum consists of a broadband and a number of sharp peaks. For SiH2 and SiD2, the sharp peaks correspond to the resonance structure of the vibrational levels of the B state and the broadbands are nearly independent of the photon energy. The broadband for SiHD increases steeply with the photon energy above 30,000 cm(-1). The flux leaving the computational grid for SiH2 and SiD2 consists of at least two components, whereas that for SiHD consists of only a faster component. These large isotope effects were discussed based on the valley to the dissociation channel on PES and the difference in the position of the initial wave packet for three isotopomers.     

Analogue chromophore study of the influence of electronic perturbation on color regulation of photoactive yellow protein

We report a unique lambdamax shift of the absorption maximum of a photoactive yellow protein (PYP) analogue reconstituted with a fluorinated chromophore (F-PYP). The difference in lambdamax between the free chromophore and the protein was significantly larger than that with the native chromophore. We concluded that the unusual lambdamax shift is caused by the electronegative character of the fluorine atom and not by steric hindrance. This result suggests that formation of a hydrogen bond between the fluorine atom and one or more amino acid residues could neutralize its electron-withdrawing character. The properties of analogues of PYP with brominated and methylated chromophore could be explained as an effect of steric hindrance.     

Chemical and biological evaluation on scopadulane-type diterpenoids from Scoparia dulcis of Vietnamese origin

From the aerial parts of Scoparia dulcis L. (Scrophulariaceae) grown in Vietnam, four scopadulane-type diterpenoids (4-7), of which 7 is new and was given the trivial name scopadulcic acid C, together with nine known compounds were isolated. Their structures were elucidated by spectroscopic analyses. The absolute configurations of 4-7 were ascertained by applying the modified Mosher's method to iso-dulcinol (6). The isolation of the lignans nirtetralin and niranthin for the first time from S. dulcis is also of chemotaxonomic interest. The cytotoxic activity in KB cells, inhibitory effect on LPS/IFNgamma-induced NO production, inhibition of multidrug resistance (MDR), and antibacterial and antifungal activities of the scopadulane-type diterpenoids 4-7 were examined in this study.     

A self-contained polymeric 2-DE chip system for rapid and easy analysis

We developed a polymeric 2-DE chip system. The chip consisted of an IEF region, an SDS-PAGE region, a valveless connection port, and a sample introduction port. A "junction structure" as a valveless connection port, which allowed separating and connecting the first- and second-dimensional gels, was fabricated between their regions. A "solution inlet" as a sample introduction port was fabricated to perform the liquid and sample introductions without solution leakage. Simultaneous sample monitoring was performed using the on-chip detection system. The performances of the system were demonstrated using commercially available proteins as a standard specimen and tissue-extracted proteins as the real samples. All procedures were employed without any movement of relocation part. This new 2-D separation system realized improved labor-intensive operations and a reduced experimental time.     

绿肥对华北潮土土壤可溶性有机物的影响

在华北潮土上种植不同绿肥,于绿肥翻压前原位采集其地上部及土壤样品,进行56d的绿肥翻压模拟试验。设毛叶苕子(Vicia villosa Roth.)、二月兰(Orychophragmus Violaceus L.)、黑麦(Secale cereale L.)三个绿肥处理和无绿肥对照处理,分析培养过程中土壤可溶性有机物(DOM)组分及其紫外-可见光谱参数的变化,以探究绿肥对土壤DOM的影响。种植和翻压绿肥增加土壤可溶性有机碳(DOC)、总有机酸碳(TOAs)和总碳水化合物碳(TCs)含量,三者的变化趋势一致,各处理均在培养第1 d上升至峰值后迅速下降。毛叶苕子提高DOC和TOAs的效果最好,最高比对照增加114.01%(培养第1d)和109.10%(培养第14 d)。黑麦提高TCs的效果最好,最高比对照增加323.18%(培养第42 d)。种植和翻压绿肥增加土壤可溶性有机氮(DON)含量,与DOC变化趋势不同,各处理在培养第1 d上升后迅速下降一段时间后又迅速上升。毛叶苕子提高DON的效果最好,最高比对照增加305.83%(培养第42d)。绿肥增加了SUVA₂₅₄,SUVA₂₆₀,SUVA₂₇₂,SUVA₂₈₀,SAUC_240-400,降低了A₂₅₀/A₃₆₅和A₂₄₀/A₄₂₀。紫外-可见光谱参数的主成分分析显示SUVA₂₅₄,SUVA₂₆₀,SUVA₂₇₂,SUVA₂₈₀间有很高正相关性,A₂₅₀/A₃₆₅和A₂₄₀/A₄₂₀间亦有很高正相关性,SAUC_240-400是这些参数中表征DOM性质的关键因子。综上结果表明,种植翻压绿肥增加了土壤DOM含量,提高了土壤DOM的芳香性、疏水性、腐殖化程度、平均分子量,增加了土壤DOM的稳定性。     

Glucosylated sesquiterpene alcohols from Fraxinus griffithii

Phytochemical investigation of the leaves of Fraxinus griffithii has led to the isolation of two new glucosylated acyclic sesquiterpene alcohols, griffithosides D (1) and E (2), along with iridoid and secoiridoid glycosides. The molecular structures of these compounds were elucidated using NMR, MS and other spectroscopic techniques, as well as comparison with literature data. The isolated compounds were tested for radical-scavenging activity and cytotoxicity against A549 human lung adenocarcinoma cells and Leishmania major parasites.