The inhibition of superoxide anion generation by neutrophils from Viscum articulactum

Two new flavanones, (2S)-pinocembrin 7-O-[beta-D-apiosyl(1-->2)]-beta-D-glucoside (1), and (2S)-pinocembrin 7-O-[cinnamoyl(1-->5)-beta-D-apiosyl(1-->2)]-beta-D-glucoside (2) together with eighteen known compounds, which include five known flavanones, nine benzenoids, one inositol and three triterpenoids, were isolated and characterized from fresh Viscum articulactum. Structures of new compounds were determined by spectral analysis. Among them, oleanolic acid (18) showed a significant inhibition effect on superoxide anion generation by human neutrophils in response to formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP).     

Iron oxide nanoparticles within the pore system of mesoporous SBA-15 in different acidity: the synthesis and characterization

Direct hydrothermal method is employed for incorporating iron into the pore structure of SBA-15. The resultant materials were analyzed by X-ray diffraction (XRD) patterns, N₂ sorption isotherm and X-ray photoelectron spectroscopy (XPS). The characterizations of XRD patterns and XPS revealed that iron nanoparticles were present as highly dispersed nanoclusters in the well-ordered mesoporous channels of SBA-15. The characterizations of t-plot reveal only microporous channels of SBA-15 are confirmed to be filled with iron nanoparticles, leaving the mesopores unaffected. The supported material still maintained its ordered mesoporous structure similar to SBA-15 and possessed high surface area, large pore volume and uniform pore size.     

Preparation of the stabilized glycoenzymes by cross-linking their carbohydrate chains

Each of the three high-mannose type glycoproteins studied, acid phosphatase, invertase, and glucose oxidase, could be specifically cross-linked through its carbohydrate chains. The procedure involves periodate oxidation of carbohydrate residues followed by reaction of the generated aldehyde groups with adipic acid dihydrazide as a cross-linker. The amount and size as well as solubility of the formed polymers could be efficiently controlled by varying the reaction conditions, i.e., the oxidation degree and the concentrations of glycoproteins, cross-linker, and hydrogen ions during the cross-linking reaction. It was found that the quantity and size of polymers increased with oxidation degree and protein concentration and by lowering the pH. When the protein concentration was above and pH below certain values, depending on the glycoenzyme, insoluble polymers formed. The soluble cross-linked polymers retained a high level of original activity, and the minor decrease in specific activity noticed was shown to occur during the periodate oxidation step. The cross-linked glycoenzymes are much more resistant to denaturation by high temperature and by changes in pH, demonstrating the usefulness of this method in preparation of the stabilized glycoprotein derivatives.     

Smectic Bimetallomesogens: Synthesis and Mesomorphic Properties in Oxygen-Bridged Dicopper and Divanadyl Complexes

The synthesis and mesomorphic properties of a homologous series of N-(3-hydroxypropyl)-4-alkoxylsalicylaldimine, N-(3-hydroxypropyl)-4-(4′-alkoxybenzoxy)salicylaldimine, and their dicopper(II) and di-oxovanadium(VI) complexes are reported. Copper complexes exhibited monotropic smectic A phases; however, vanadyl complexes showed no mesomorphism. A systematic comparison revealed that the meso-genie behaviors of these bimetallic complexes are induced by the weak intermolecular force and determined mainly by the central metal. The effects on the structural variations near the metal central cores and side chain density are also discussed.     

Cytotoxic Principles from Saussurea Lappa and Corydalis Turtshaninovii f. Yanhusuo

Four protoberberine alkaloids, berberine, palmatine, dehydrocorydaline and coptisine were characterized as cytotoxic principles from the tuber of Corydalis turtshaninovii f. yanhusuo. On the other hand, dehydrocostus lactone and costunolide demonstrated cytotoxicity from the root of Saussurea lappa. Their structures were elucidated by spectral analyses.     

The Constituents of the Stem and Roots of Aristolochia foveolata

One new aristolactam glucoside: aristolactam-Ia-N-D-glucoside together with seventeen known compounds were isolated from the fresh stems and roots of Aristolochia foveolata. Their structures were determined by spectral and chemical methods. Among seven aristolochic acid derivatives, five were determined to be salt forms by IR and ¹H NMR methods.     

Fabrication of Mesoporous CoS2 Nanotube Arrays as the Counter Electrodes of Dye‐Sensitized Solar Cells

Mesoporous cobalt sulfide nanotube arrays on FTO‐coated glass were synthesized by combining three simple technologies: the selective etching of ZnO sacrificial templates, mesoporous Co₃O₄ formation from cobalt‐chelated chitosan, and ion‐exchange reaction (IER). The mesoporous Co₃O₄ nanotubes composed of the Co₃O₄ nanoparticles possess a high surface area and are taken advantage for further removal of templates and IER. The morphologies and crystal structures of the CoS₂ nanotube arrays were characterized by SEM, TEM, and XRD analyses. Their electrocatalytic properties were determined by electrochemical analyses including cyclic voltammetry measurements and Tafel polarization. The DSSCs assembled with a CoS₂ counter electrode achieved a power conversion efficiency of 6.13 %, which was comparable to that of the DSSC with the Pt counter electrode (6.04 %). This indicates that the mesoporous CoS₂ nanotube array can be a low‐cost and efficient alternative for the reduction of electrolytes in DSSCs.     

Facile synthesis of polymerized ionic liquids with high thermal stability

Twelve main-chain-type polymerized ionic liquids that have alkylimidazolium cation units were prepared using simple synthetic processes. The polymers were prepared using the self-polymerization of a single monomer; no polymerization initiators were required. The thermal stability and solvent miscibility of these polymers were studied. Results show that the combined anions greatly influence the solubility and thermal stability of the polymers. Among these polymers, poly-alkylimidazolium bis(trifluoromethylsulfonyl)imide polymers exhibited the highest thermal stability (>400 °C), which makes them candidates for many applications.     

New Spectral Techniques: Time-Resolved Fourier-Transform Spectroscopy and Two-Color Laser-Induced Grating Spectroscopy

Time-resolved Fourier-transform spectroscopy and two-color laser-induced grating spectroscopy are two new techniques recently employed in this laboratory. We recorded emission in the near infrared region during laser photolysis of HONO₂ with a step-scan Fourier-transform spectrometer and achieved temporal resolution in the microsecond range and spectral resolution of 0.1 cm¹. Rotationally resolved emission lines of the (0,0) band of the D ²∑⁺ →A ²∑ ⁺ transition of NO in the region 8900-9300 cnv^?1 with irregular relative intensities were observed when an ArF excimer laser was used to photodissociate HONO₂. The spectroscopic parameters of both D ²∑⁺ and A ²∑⁺ states agree with those previously reported. When a narrow-band ArF laser was used, selective rotational levels of the D state of NO were populated depending on the wavelength of the ArF laser. Our results indicate that absorption of a 193-nm photon by NO(υ″ = 1) is responsible for the observed emission. To test the technique of two-color laser-induced grating spectroscopy, we employed the B ³II_0U⁺-X ¹∑_g ⁺ system of I₂. Background-free spectra with transitions involving rotationally selected states were recorded. Various experimental schemes were employed with population gratings formed in either the B or X state. Signals due to different four-wave mixing schemes were distinguished by variation of relative timing between the grating beams and the probe beam.     

Fabrication and characterization of core-shell photonic crystals via a dipping process

High-quality polystyrene (PS) colloidal photonic crystals in large area were fabricated in 24 h via a capillary-enhanced process. Then, the photonic crystals with core-shell structure were obtained by incorporating silica nanoparticles into the interstitial space of opal template via a dipping process. The filling ratio (V_silica) of interstitial space could be manipulated by dipping colloidal crystals into suspensions with different concentrations of silica nanoparticles, which in turn renders the obtained core-shell photonic crystals. The absorptive peak of opal without dipping process is at 445 nm as measured by UV–vis spectrometry. The filling ratios of 0.130, 0.167 and 0.253 can be calculated according to the modified Bragg's Law, which corresponds to the absorptive peaks for core-shell opals at 453, 463 and 469 nm obtained from suspensions with silica nanoparticles of 0.017, 0.122, and 0.244 wt%, respectively. Therefore, by using this dipping process, the characteristic absorption wavelength for photonic crystal will be varied easily, efficiently and cost effectively than that by traditional methods for constructing opal from monodispersed colloids of different diameters.