Enantioselective heterocyclic synthesis of spiro chromanone-thiochroman complexes catalyzed by a bifunctional indane catalyst

Novel asymmetric domino reactions of benzylidenechroman-4-ones and 2-mercaptobenzaldehydes for efficient construction of spiro chromanone-thiochroman complexes were accomplished with high yields and excellent selectivities via a novel bifunctional indane catalyst.     

Involvement of reactive oxygen species and calcium in photo-induced membrane damage in HeLa cells by a bis-methanophosphonate fullerene

Photo-excited bioactivities of fullerene derivatives are attracting much attention. In this report, a bis-methanophosphonate fullerene (BMPF) and the other two fullerene derivatives, a bis-malonic acid fullerene (BMAF) and a fullerol were incubated with HeLa cells and irradiated with a green light emitted from a mercury lamp on a fluorescent microscopy. By using DNA fluorescent probe propidium iodide staining method, damage towards cell membrane could be detected when cells were treated by irradiation altogether with BMPF or BMAF at a low concentration (4 μM), and the damage was dose-dependent. The activity of BMPF was much higher than that of BMAF, while fullerol had no effects under the same condition. It was also revealed that different kinds of reactive oxygen species (ROS) correlated to BMPF and BMAF. Additionally, presence of extracellular calcium could promote the activities of both derivatives, while removal of extracellular calcium could not abort their membrane-damaged activities. These results indicated that ROS and calcium were involved in the photosensitization of fullerene derivatives, and BMPF was a superior photosensitizer which would find potential application in biomedical field.     

The spectrum sequences of periodic frame multiresolution analysis

The periodic multiresolution analysis （PMRA） and the periodic frame multiresolution analysis （PFMRA） provide a general recipe for the construction of periodic wavelets and periodic wavelet frames, respectively. This paper addresses PFMRAs by the introduction of the notion of spectrum sequence. In terms of spectrum sequences, the scaling function sequences generating a normalized PFMRA are characterized; a characterization of the spectrum sequences of PFMRAs is obtained, which provides a method to construct PFMRAs since its proof is constructive; a necessary and sufficient condition for a PFMRA to admit a single wavelet frame sequence is obtained; a necessary and sufficient condition for a PFMRA to be contained in a given PMRA is also obtained. What is more, it is proved that an arbitrary PFMRA must be contained in some PMRA. In the meanwhile, some examples are provided to illustrate the general theory.     

Electrochemical capacitances of well-defined carbon surfaces

Reported is the capacitive behavior of homogeneous and well-defined surfaces of pristine carbon nanofibers (CNFs) and surface-modified CNFs. The capacitances of the well-defined CNFs were measured with cyclic voltammetry to correlate the surface structure with capacitance. Among the studied pristine CNFs, the edge surfaces of platelet CNFs (PCNF) and herringbone CNFs were more effective in capacitive charging than the basal plane surface of tubular CNF by a factor of 3-5. Graphitization of PCNF (GPCNF) changed the edge surface of PCNF into a domelike basal plane surface, and the corresponding capacitances decreased from 12.5 to 3.2 F/g. A chemical oxidation of the GPCNF, however, recovered a clear edge surface by removal of the curved basal planes to increase the capacitance to 5.6 F/g. The difference in the contribution of the edge surface and basal-plane surface to the capacitance of CNF was discussed in terms of the anisotropic conductivity of graphitic materials.     

Preparative isolation of hydrolysable tannins chebulagic acid and chebulinic acid from Terminalia chebula by high-speed counter-current chromatography

As a chromatographic column, the high-speed counter-current chromatography system was equipped with a preparative HPLC series, enabling the successful isolation of hydrolysable tannins from the fruits of Terminalia chebula, a traditional Chinese medicine. The two-phase solvent system was composed of n-hexane-ethyl acetate-methanol-water (1:20:1:20 v/v). As a result, 33.2 mg chebulagic and 15.8 mg chebulinic acids were obtained in one step from 300 mg of crude extract. Their purities were determined by HPLC to be 95.3 and 96.1%, respectively. The chemical structures were identified by their MS and 1H NMR spectra.     

Perturbation of Yamabe equation on Iwasawa N groups in presence of symmetry

Let G be a simple Lie group of real rank one and N be in the Iwasawa decomposition of G. Under the assumption of some symmetries, we obtain an existent result for the nonlinear equation △NU ＋ （1 ＋ ∈K（x, z））u2＊-1 = 0 on N, which generalizes the result of Malchiodi and Uguzzoni to the Kohn＇s subelliptic context on N in presence of symmetry.     

Multiple forced rotational solutions for the planar <Emphasis Type="Italic">N</Emphasis>-pendulum equation

This paper presents a theorem of existence of \((N - N_{0} + 1)2^{N_{0}}\) noncontractible periodic orbits of any given rotational vector with zero components for the planar forced N-pendulum equation, where N₀ denotes the number of zero components of given rotational vector. We make special arrangements for masses and length instead of the nondegenerate assumption. Moreover, for rotational vectors with identical components, similar results is also obtained.     

Assay of vitamin B in urine by capillary electrochromatography with methacrylate-based monolithic column

A novel and simple method for the separation of major vitamin B analytes, such as thiamine, riboflavin, nicotinamide, vitamin B4, pyridoxine, has been developed by CEC using the monolithic column. It has been found that the baseline separation of the five analytes could be achieved with 5.0 mM phosphate buffer at pH 4.0. Compared with the open-tubular capillary and the bared capillary columns, the poly(butylmethacrylate-co-ethylene glycol dimethacrylate) monolithic capillary could exhibit the best resolution in the analysis. Then the method was validated and the linear calibration ranges were obtained with correlation coefficients more than 0.997. The precision and the recovery were also investigated and showed a good result. Furthermore, the proposed method was successfully applied to assay the concentration of vitamin B analytes and the metabolic situation in human urine samples.