Chemical constituents from rauvolfia verticillata and bioactivities research

A new acridone alkaloid, named 9-hydroxynoracronycine (1), together with four known compounds, including coumarins, lignan, and indole alkaloid, was isolated and identified from the roots and rhizomes of Rauvolfia verticillata. The structure of the new compound was determined by spectroscopic means (UV, IR, MS, and NMR). The acridone alkaloid and coumarins were identified as new constituents of Rauvolfia genus. The cytotoxic activities of the new compound were tested against human breast cancer cell line MCF-7 and human promyelocytic leukemia HL-60. Results showed that compound 1 decreased MCF-7 cell proliferation in a statistically IC₅₀ significant manner at 102.8 μmol/L. In addition, compound 1 exhibited moderate small intestine smooth muscle relaxation.     

High resolution two-dimensional dose mapping of electron beam processed polymers

The recent advances in electron beam processing of polymer samples require increasingly dose mapping techniques with depth and volume resolution capability. In this paper, the use of micro-indentation and thermo-mechanical analysis is proposed to fulfill the necessary requirements in terms of resolution and accuracy. Experimental procedures are used to acquire mechanical data that are successively converted into dose levels based on dedicated calibrated samples. Physical principles, experimental artifacts, and limitations are discussed with special focus on calibration and validation of a simulator for dosimetry in electron beam cross-linking of electrical cables.     

An LC‐MS method for simultaneous determination of nine ginsenosides in rat plasma and its application in pharmacokinetic study

A sensitive and reliable LC‐ESI‐MS method for simultaneous determination of nine ginsenosides (Rh₁, Rg₂, Rg₁, Rf, Re, Rd, Rc, Rb₂ and Rb₁) in rat plasma was developed and validated using saikosaponin A as an internal standard. The samples were extracted by solid‐phase extraction. Chromatographic separation was carried out on a Hypersil Gold C₁₈ column (100 × 2.1 mm, 5 µm) by stepwise gradient elution with water (0.1% formic acid, v/v) and acetonitrile as the mobile phase. Detection was determined by selective ion monitoring mode using electrospray ionization in the negative ion mode. Good linearity over the investigated concentration ranges was observed with the values of r higher than 0.9900. The intra‐ and inter‐day precisions were all no more than 15% and the average recoveries varied from 71.8 to 91.7%. This quantitative measurement was successfully applied to a pharmacokinetic study of Yi‐Qi‐Fu‐Mai injection. Copyright © 2010 John Wiley & Sons, Ltd.     

Porous V2O5 -SnO2 /CNTs composites as high performance cathode materials for lithium-ion batteries

Vanadium pentoxide (V2O5 ) exhibits high theoretical capacities when used as a cathode in lithium ion batteries (LIBs), but its application is limited by its structural instability as well as its low lithium and electronic conductivities. A porous composite of V2O5 -SnO2 /carbon nanotubes (CNTs) was prepared by a hydrothermal method and followed by thermal treatment. The small particles of V2O5 , their porous structure and the coexistence of SnO2 and CNTs can all facilitate the diffusion rates of the electrons and lithium ions. Electrochemical impedance spectra indicated higher ionic and electric conductivities, as compared to commercial V2O5 . The V2O5 -SnO2 /CNTs composite gave a reversible discharge capacity of 198 mAh g-1 at the voltage range of 2.05 4.0 V, measured at a current rate of 200 mA g-1 , while that of the commercial V2O5 was only 88 mAh g-1 , demonstrating that the porous V2O5 -SnO2 /CNTs composite is a promising candidate for high-performance lithium secondary batteries.     

Copper(II) mediated C–H methylthiolation of 2-phenyl pyridines with dimethyl sulfoxide using an amino acid ligand

A novel protocol for the C–H methylthiolation of 2-phenyl pyridines using DMSO as the methylthio source and an amino acid ligand is described. This simple procedure requires neither an oxidant nor additional solvent. The developed protocol tolerates a wide range of functional groups including methyl, methoxy, fluoro, chloro, and in particular the formyl group. This new strategy is highly regioselective and provides aryl methyl sulfides from 2-phenyl pyridines in moderate to good yields.     

A unification of unitary similarity transforms to compressed representations

In this paper a new framework for transforming arbitrary matrices to compressed representations is presented. The framework provides a generic way of transforming a matrix via unitary similarity transformations to, e.g., Hessenberg, Hessenberg-like form and combinations of both. The new algorithms are deduced, based on the QR-factorization of the original matrix. Relying on manipulations with rotations, all the algorithms consist of eliminating the correct set of rotations, resulting in a matrix obeying the desired structural constraints. Based on this new reduction procedure we investigate further correspondences such as irreducibility, uniqueness of the reduction procedure and the link with (rational) Krylov methods. The unitary similarity transform to Hessenberg-like form as presented here, differs significantly from the one presented in earlier work. Not only does it use less rotations to obtain the desired structure, also the convergence to rational Ritz-values is not observed in the conventional approach.     

Two new secoiridoid glucosides from Syringa velutinai Kom.

Chemical investigation of Syringa velutinai Kom. led to the isolation of two new secoiridoid glucosides. Their structures were identified as 6'-O-(6, 7-dihyrofoliamenthoyl)-8-epi-kingisidic acid (syrveoside A, 1) and 6'-O-menthiafoloyl-8-epi-kingisidic acid (syrveoside B, 2) on the basis of chemical and physicochemical evidence.     

Effect of surface micro-topography of titanium material on the behaviors of rabbit osteoblast in vitro

To study interactions of osteoblast on different topography surfaces of titanium material through in vitro systems, four kinds of micro-topography surfaces on novel titanium material were investigated. They were laser-scanned surface (LS), sandblasted surface (SS), machine-tooled surface (MS) and polished surface (PS). The titanium samples were seeded with osteoblast and maintained for a period of 1-12 days. Adhesion in 24 h, proliferation in 12 days and ALP activity in 11 days were assessed. The cell morphologies were observed by scanning electron microscopy and fluorescence microscopy. The investigation showed better cell proliferation and best cell osteogenic differentiation on the micro-grooved surface (LS) at the cell scale (50 μm). Furthermore, osteoblast on the micro-grooved surfaces also displayed a more similar morphology to osteoblast in vivo. It was shown that surface micro-texture at the cell scale have a better effect on cell responses than rough surface and surface texture above the cell scale (>100 μm). The regular micro-grooved titanium surface at the cell scale can offer a better cell growth environment compared with the other titanium surfaces.     

A new flavonoid with a benzoic acid substituent from Selaginella uncinata

6-（5-Carboxyl-2-methoxyphenyl）-apigenin （1）, a new flavonoid, was isolated from the 60% ethanol extract of Selaginella uncinata （Desv.） Spring. Its structure was established by spectroscopic methods. Compound 1 represents the first example of the flavonoids possessing a benzoic acid substituent at C-6.     

Investigating the morphology and mechanical properties of blastomeres with atomic force microscopy

Atomic force microscopy (AFM) was used to directly investigate the morphology and mechanical properties of blastomeres during the embryo development. With AFM imaging, the surface topography of blastomeres from two‐cell, four‐cell, and eight‐cell stages was visualized, and the AFM images clearly revealed the blastomere's morphological changes during the different embryo developmental stages. The section measurements of the AFM topography images of the blastomeres showed that the axis of the embryos nearly kept constant during the two‐cell, four‐cell, and eight‐cell stages. With AFM indenting, the mechanical properties of living blastomeres from several embryos were measured quantitatively under physiological conditions. The results of mechanical properties measurements indicated that the Young's modulus of the two blastomeres from two‐cell embryo was different from each other, and the four blastomeres from the four‐cell embryo also had variable Young's modulus. Besides, the blastomeres from two‐cell embryos were significantly harder than blastomeres from four‐cell embryos. These results can improve our understanding of the embryo development from the view of cell mechanics. Copyright © 2013 John Wiley & Sons, Ltd.