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131.
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133.
Marcello Baldo Renato Pucci Pasquale Tomasello 《International journal of quantum chemistry》1983,23(3):1111-1119
In the framework of the PPP Hamiltonian, we have studied the low-lying spectra of all trans linear polyenes with the dielectirc function method. It is shown that higher order processes, not included in the RPA scheme as local field correction (LFC) and self-energy (SE) effects can be introduced in a effective way by a suitable parametrization of the residual coulomb interaction. This parametrization is fixed along the polyene series both for singlet and triplet states, at variance with previous RPA calculations. Comparison with the most refined CI calculations, as well as with the experimental findings shows very good agreement. Furthermore, chain length and geometry dependence of the electron–electron correlation is briefly discussed. 相似文献
134.
Pasquale Piraino Giuseppe Tresoldi Felice Faraone 《Journal of organometallic chemistry》1982,224(3):305-312
The syntheses of [Rh(diol)(formamidine)]2 complexes (diol cycloocta-1,5-diene (1); diol norbornadiene (2); formamidine N,N′-di-p-tolylformamidine) are reported. These complexes are dimeric and contain the bridging formamidino ligand. They react with CO, dppe and PPh3 with displacement of the diene ligand to yield the known [Rh(CO)2(formamidine)]2, [Rh(dppe)2]+ and [Rh(PPh3)2(formamidine)], respectively; the last complex, in which the formamidine acts as a chelating ligand, was isolated only as the O2 adduct. With HCl or HBF4 aqueous 1 and 2 do not form hydrides but instead the formamidino cation [p-tolyl-NHCHNHtolyl-p]+ and the complexes [Rh(diol)X]2 (X Cl, F); a possible scheme for the reaction with HCl is proposed. The [Rh(C8H12)(formamidine)]2 complex reacts with heterocumulenes as CS2, SO2, PhNCS and PhNCO with diene displacement; the only product isolated was [Rh(CS2)2(formamidine], to which a polymeric structure is assigned. 相似文献
135.
136.
Mitnik L Novotny M Felten C Buonocore S Koutny L Schmalzing D 《Electrophoresis》2001,22(19):4104-4117
A number of significant improvements in the electrophoretic performance and design of DNA sequencing devices have culminated in the introduction of truly industrial grade production scale instruments. These instruments have been the workhorses behind the massive increase in genomic sequencing data available in public and private databases. We highlight the recent progress in aspects of capillary electrophoresis (CE) that has enabled these achievements. In addition, we summarize recent developments in the use of microfabricated devices for DNA sequencing that promise to bring the next leap in productivity. 相似文献
137.
Lo Schiavo S Mineo P Tresoldi G Cardiano P Piraino P 《Dalton transactions (Cambridge, England : 2003)》2005,(18):2979-2981
A novel class of polymers was obtained by insertion of dirhodium(II,II) metal systems into a methacrylate backbone; the synthesis was realized by free radical polymerization of an appropriate methacrylate-functionalized dirhodium polymer precursor, namely [Rh2(form)2(MA-COO)2](form =N,N'-di-p-tolylformamidinate)(MA-COO = 2-(methacroyloxy)ethyl-phthalate), with methylmethacrylate (MMA); the new copolymers, in solution, show reversible CO-absorption, connected to the axial reactivity of dirhodium(II,II) species. 相似文献
138.
Polymer based interfaces as bioinspired 'smart skins' 总被引:1,自引:0,他引:1
This work reports on already achieved results and ongoing research on the development of complex interfaces between humans and external environment, based on organic synthetic materials and used as smart 'artificial skins'. They are conceived as wearable and flexible systems with multifunctional characteristics. Their features are designed to mimic or augment a broad-spectrum of properties shown by biological skins of humans and/or animals. The discussion is here limited to those properties whose mimicry/augmentation is achievable with currently available technologies based on polymers and oligomers. Such properties include tactile sensing, thermal sensing/regulation, environmental energy harvesting, chromatic mimetism, ultra-violet protection, adhesion and surface mediation of mobility. Accordingly, bioinspired devices and structures, proposed as suitable functional analogous of natural architectures, are analysed. They consist of organic piezoelectric sensors, thermoelectric and pyroelectric sensors and generators, photoelectric generators, thermal and ultra-violet protection systems, electro-, photo- and thermo-chromic devices, as well as structures for improved adhesion and reduced fluid-dynamic friction. 相似文献
139.
Potassium niobium silicate (KNS) glasses the composition of which is characterized by the K2O/Nb2O5 molar ratio ranging from 0.85 to 1.2 and SiO2 50-54 mol% were examined in order to clarify the influence of chemical composition on formation of transparent nanostructured state of glasses. Differential thermal analysis, X-ray diffraction and scanning electron microscopy were used to study the non-isothermal crystallization of the KNS glasses as well as their morphological features. It was found that all glasses devitrify in three steps forming unidentified phases at the first two ones while at higher temperature (1000-1100 °C) the crystallization of K3Nb3O6Si2O7 takes place. For prolonged heat treatment time (more than 5 h) at high temperature (1050-1100 °C) the transformation of this phase into the KNbSi2O7 ferroelectric one occurs in some extent. Nanostructuring occurs at the first stage of the devitrification process. It results from two partially overlapped processes: amorphous phase separation and subsequent crystallization. It was shown that only for the glass with the K2O/Nb2O5 molar ratio equal to 0.85 and SiO2 50 mol% it is possible to separate the above processes by isothermal heat treatments at 680 °C obtaining fully transparent nanostructured samples. These samples contain nanocrystals 10 times smaller than the amorphous inhomogeneities of the phase separated matrix in which are dispersed. 相似文献
140.
Pasquale Longo Antonio Proto Patrizia Oliva Irene Sessa Adolfo Zambelli 《Journal of polymer science. Part A, Polymer chemistry》1997,35(13):2697-2702
Copolymerization of styrene with (Z)-1,3-pentadiene affords copolymers mostly containing 1,2 pentadiene units. Both the styrene and the pentadiene units are in syndiotactic arrangement but the comonomer sequence distribution is far from bernoullian. Interestingly, the behavior of (Z)-1,3-pentadiene does not change much when polymerization temperature raises from −20 to +20°C, notwithstanding that (Z)-1,3-pentadiene affords a 1,2-syndiotactic homopolymer at −20°C but a prevailingly 1,4 cis homopolymer at +20°C. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2697–2702, 1997 相似文献