Cycloaddition of arynes with iodonium ylides: a mild and general route for the synthesis of benzofuran derivatives

A mild and general cycloaddition of arynes with iodonium ylides protocol has been developed for the synthesis of benzofurans. In the presence of CsF, ortho-silyl aryltriflates were reacted with iodonium ylides smoothly at room temperature in moderate to good yields.     

接枝共聚法制备二氧化钛/聚（苯乙烯-二乙烯基苯）复合微球

本文以KH560、苯乙烯、马来酸酐为连接组分,将二氧化钛接枝到聚（苯乙烯-二乙烯基苯）微球的表面,成功制备了无孔和多孔纳米复合微球。研究了硅烷偶联剂（KH560）和苯乙烯对二氧化钛在无孔微球表面的分散性和接枝数量以及支撑微球的多孔性质对接枝到微球内部的二氧化钛数量的影响。结果表明,KH560和苯乙烯能够提高二氧化钛在微球表面的分散性和稳定性,使二氧化钛以30-80nm的粒径接枝在微球表面。苯乙烯又能使二氧化钛在无孔微球表面的接枝数量从10.4%增大到20.4%。平均孔径为136nm的多孔微球为支撑微球得到的复合粒子中二氧化钛最高接枝量可达26%,明显高于无孔微球和平均孔径为31nm的多孔微球。     

The influence of nanoparticle architecture on latex film formation and healing properties

We present a study of chain interdiffusion in films formed by specially architectured PBMA nanoparticles by Förster Resonance Energy Transfer – FRET. Polymer nanoparticles contained linear chains with narrower molecular weight distributions than other previous reports, allowing a more detailed study. Apparent fractions of mixing and diffusion coefficients, determined from the quantum efficiency of energy transfer, were used to characterize the interdiffusion mechanism in the different films. The resistance of the films to dissolution by a good solvent was finally correlated with the interdiffusion results, in order to get information about film healing. We concluded that whenever interdiffusion occurs between nanoparticles containing linear chains and fully cross-linked nanoparticles, healing becomes more effective in spite of showing slower interdiffusion. We also observed that particles with longer chains are more effective for film healing. Finally, we concluded that interdiffusion occurs both ways across interfaces in blends formed by particles swollen with linear chains of different molecular weights.     

Dual signaling system with an extended-tetrathiafulvalene-phenanthroline dyad acting as an electrooptical cation chemosensor

An efficient synthesis of unprecedented fused extended-tetrathiafulvalene-dipyridoquinoxaline (exTTF-dpq) dyad is described through the Horner-Wardsworth-Emmons olefination methodology from the dipyrido[3,2-a:2',3'-c]-benzo[3,4]phenazine-11,16-quinone (NqPhen) ligand starting material. This exTTF-dpq dyad is demonstrated to act as a dual redox and colorimetric sensor for cations exploiting the proximity between the redox tetrathiafulvalene and the optical phenanthroline detecting sites. Its ability for sensing cations from the d-group metal transitions (Fe(2+), Ni(2+), and Zn(2+)) and also with varied cations such as Ca(2+) and Pb(2+) is presented.     

Lycopene/arabinoxylan gels: rheological and controlled release characteristics

Arabinoxylan gels exhibiting different rheological and lycopene transport properties were obtained by modifying the polysaccharide concentration from 3 to 4% (w/v). The apparent lycopene diffusion coefficient decreased from 2.7 × 10?? to 2.4 × 10?? cm2/s as the arabinoxylan concentration in the gel changed from 3 to 4% (w/v). A low amount of lycopene is released by diffusion from arabinoxylan gels. These results indicate that arabinoxylan gels could be carriers for lycopene delivery in specific sites after network degradation. The possibility to modulate lycopene release from arabinoxylan gels makes these biomaterials potential candidates for the controlled delivery of biomolecules.     

Orientation Imaging in Scanning Electron and Transmission Electron Microscopy for Characterization of the Shear Banding Phenomenon

The texture evolution during deformation of high purity fcc single crystals with initial (112) [11 ] orientation has been characterised in detail by transmission (TEM) and scanning (SEM–FEG) electron microscopes. The channel-die deformed samples up to reduction of about 1–1.5, first developing strongly anisotropic layers of elongated cells or twin-matrix plates and then compact clusters of SB. Substantial progress in understanding the mechanism of the SB formation was possible thanks to systematic local orientation measurements (orientation mapping) using SEM and TEM. These two techniques of local orientation measurements have been compared with respect to their applicability for the study of shear banding phenomenon and for characterization of the specific nanostructure of SB in metals with fcc lattice. It was shown that well-developed SB exhibit large orientation spreads up to 35–40° with respect to the adjacent areas outside the band. Most of these misorientations occur by rotations about the TD‖〈110〉 axis with significant further rotations about 〈112〉 poles. This ultimately leads to the formation of the texture components whose occurrence cannot be explained by models homogeneous deformation.     

Identification of triterpenoid compounds of Centella asiatica by thin-layer chromatography and mass spectrometry

The identification of the four principal triterpenoid components of Centella asiatica has been achieved by TLC on silica gel plates and mass spectrometry, as a modification of the method described in the European Pharmacopoeia (5th edn). A combination of ethyl acetate and methanol as the mobile phase was found to be successful in separating these compounds from the rest of the main components of the extract. The spots were detected with anisaldehyde solution. The separated compounds were confirmed by MALDI -TOF mass spectrometry.     

Superabsorbing fullerenes: spectral and kinetic characterization of photoinduced interactions in perylenediimide-fullerene-C60 dyads

Two n-type molecular materials are covalently combined into a new photovoltaic component for polymer solar cells. Light harvesting by the perylenediimide results in very fast energy transfer to the fullerene unit, as shown with femtosecond transient absorption spectroscopy in toluene solution. Two energy transfer rates are observed of 2.5 x 10(12) s-1 (53%) and 2 x 10(11) s-1 (47%), attributed to two conformations. The final excited state that is populated is a perylenediimide-based triplet state that is formed on the nanosecond time scale with a high yield.     

A modified Chan-Vese model and its theoretical proof

We present a modified Chan-Vese functional and give its theoretical proof. By using the geometric heat flow method to all the Euler-Lagrange equations, a system of evolution equations in level set formulation is derived. We study the existence of solution to this system by Schauder fixed point theorem and the implicit function theorem in Banach space. This variational formulation can detect interior and exterior boundaries of desired object(s) in color images.