Search results for "Ligo"
showing 10 items of 1427 documents
Electronic Properties of Discotic LC-Materials
1996
Abstract We have made extensive studies of the charge-carrier mobilities in the discotic hexagonal mesophases of triphenylene-based discotic liquid crystals. Using the time-of-flight technique, transient photocurrents were measured yielding charge-carrier mobilities for various electric fields and temperatures. Starting from promising results obtained with the monomeric discotic liquid crystalline model compound hexapentyloxytriphenylene (H5T), we synthesized a “discotic twin” with two triphenylene units linked together by a suitable spacer. Additionally, we synthesized a discotic liquid crystalline oligomer consisting of four triphenylene units which are bound to a flexible cyclosiloxane r…
Thermal behavior of ethylene copolymers with di- and tri-alkenylsilsesquioxane comonomers synthesized by post-metallocene catalysts
2020
AbstractThis paper reported thermal properties of ethylene copolymers with di- and tri-alkenylsilsesquioxanes (POSS) synthesized by bis(phenoxy-imine) Ti, Zr, V, and V salen-type complexes. Ethylene copolymers with multi-alkenyl POSS obtained by such complexes contain multi-alkenyl POSS incorporated into the polymer chain as a side group. They were characterized by different thermal behavior depending on the kind of multi-alkenyl POSS comonomer, and type of the catalyst used, as well as polymerization conditions and thus the structure of the copolymer chain. Ethylene/POSS copolymers differed in incorporation of POSS into the polymer chain, content of specific unsaturation groups, and molecu…
Thermal stability of ethylene copolymers with multi-alkenylsilsesquioxane comonomers synthesized by organometallic catalyst - Effect of copolymer str…
2020
Abstract This study was focused on thermal properties of ethylene copolymers with di-, tri- and tetra-alkenylsilsesquioxanes (POSS) synthesized by ansa-metallocene complex. Ethylene copolymers with multi-alkenyl POSS were characterized by different thermal behavior depending on the kind of POSS comonomer and its content, as well as the copolymer structure. The copolymers differed in the incorporation way of POSS into the polymer chain (linear and crosslinked structure), content of specific unsaturation groups, molecular weight, as well as heterogeneity of polymer chain compositions. It was found that the kind and content of unsaturation groups in E/POSS copolymers played a significant role …
Ethylene/POSS copolymerization behavior of postmetallocene catalysts and copolymer characteristics
2017
Copolymerization of ethylene with iso-butyl substituted monoalkenyl(siloxy)- or monoalkenylsilsesquioxane (POSS) comonomers over bis(phenoxy-imine) and salen-type titanium and zirconium catalysts was studied. It was found that the polyreaction performance was significantly depended by the kind of the catalyst and by the structure and concentration of POSS in the feed. The POSS comonomer was efficiently incorporated into the polymer chain at up to 0.2 mol %. The differences in the copolymer compositions as the functions of the catalyst kind and the POSS comonomer were observed, including the varied number-average sequence length of ethylene and unsaturated end groups, as determined by 1H NMR…
DNA-based biosensor on flexible nylon substrate by dip-pen lithography for topoisomerase detection
2019
Dip-pen lithography (DPL) technique has been employed to develop a new flexible biosensor realized on nylon with the aim to detect the activity of human topoisomerase. The sensor is constituted by an ordered array of a DNA substrate on flexible nylon supports that can be exploited as a drug screening platform for anticancer molecules. Here, we demonstrate a rapid protocol that permits to immobilize minute quantities of DNA oligonucleotides by DPL on nylon surfaces. Theoretical and experimental aspects have been investigated to successfully print DNA oligonucleotides by DPL on such a porous and irregular substrate.
Excited state absorption spectra of dissolved and aggregated distyrylbenzene: A TD-DFT state and vibronic analysis
2017
Made available in DSpace on 2018-12-11T17:33:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-07-21 Federación Española de Enfermedades Raras Ministerio de Economía y Competitividad A time-dependent density functional theory study is performed to reveal the excited state absorption (ESA) features of distyrylbenzene (DSB), a prototype π-conjugated organic oligomer. Starting with a didactic insight to ESA based on simple molecular orbital and configuration considerations, the performance of various density functional theory functionals is tested to reveal the full vibronic ESA features of DSB at short and long probe delay times. UNESP-Universidade Estadual Paulista POSMAT-Graduate Pr…
Au@MnO nanoflowers: hybrid nanocomposites for selective dual functionalization and imaging.
2010
Recently, the development of hybrid nanostructures consisting of various materials has attracted considerable interest. The assembly of different nanomaterials with specific optical, magnetic, or electronic properties to multicomponent composites can change and even enhance the properties of the individual constituents. Specifically tuning the structure and interface interactions within the nanocomposites has resulted in novel platforms of materials that may lead the way to various future technologies, such as synchronous biolabeling, protein separation and detection, heterogeneous catalysis, and multimodal imaging in biomedicine. Of the various kinds of nanomaterials, gold nanorods show an…
Influence of Fano resonance on SERS enhancement in Fano-plasmonic oligomers
2019
Plasmonic oligomers can provide profound Fano resonance in their scattering responses. The sub-radiant mode of Fano resonance can result in significant near-field enhancement due to its light trapping capability into the so-called hotspots. Appearance of these highly localized hotspots at the excitation and/or Stokes wavelengths of the analytes makes such oligomers promising SERS active substrates. In this work, we numerically and experimentally investigate optical properties of two disk-type gold oligomers, which have different strength and origin of Fano resonance. Raman analysis of rhodamine 6G and adenine with the presence of the fabricated oligomers clearly indicates that an increment …
The glass transition of mixtures of polystyrene with alkyl-terminated oligostyrene — experimental evidence for microphase separation in a polymer ble…
1995
Mixtures of high molecular weight polystyrene (P n = 961.5 ; T g = 373 K) and sec-butyl-terminated oligostyrene (P n = 10.6 ; T g = 302 K) show a dependence of the glass transition on the composition (i.e., number-average molecular weight) which cannot be described by the classic equations of Fox & Flory or Kanig & Ueberreiter. Addition of small amounts of the oligostyrene strongly decreases the glass transition, and above an oligomer content of 40 wt.-% the glass transition remains constant within experimental error. This behavior can be attributed to the unfavorable interactions between the alkyl-terminated oligomer and the high molecular weight PS. As a result the oligomer is a bad solve…
Accelerated laboratory weathering of polypropylene composites filled with synthetic silicon-based compounds
2019
Abstract Non-functionalized and n-alkyl functionalized polyhedral oligomeric silsesquioxanes (POSS), siloxane-silsesquioxane resins and the sol-gel silicas were for the first time examined as possible UV-stabilizers and/or antioxidants in polypropylene (PP). The obtained composites were subjected to the accelerated laboratory weathering tests. The influence of the weathering conditions on the structure and properties of the PP materials was evaluated on the basis of the results from Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) studies. It was found that weathering resistance of the PP materials was strongly de…