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121.
Campidelli S Vazquez E Milic D Lenoble J Atienza Castellanos C Sarova G Guldi DM Deschenaux R Prato M 《The Journal of organic chemistry》2006,71(20):7603-7610
A second-generation cyanobiphenyl-based dendrimer was used as a liquid-crystalline promoter to synthesize mesomorphic bisadducts of [60]fullerene. Liquid-crystalline trans-2, trans-3, and equatorial bisadducts were obtained by condensation of the liquid-crystalline promoter, which carries a carboxylic acid function, with the corresponding bisaminofullerene derivatives. A monoadduct of fullerene was also prepared for comparative purposes. All the compounds gave rise to smectic A phases. An additional mesophase, which could not be identified, was observed for the trans-2 derivative. The supramolecular organization of the monoadduct derivative is governed by steric constraints. Indeed, for efficient space filling, adequacy between the cross-sectional areas of fullerene (approximately 100 A(2)) and of the mesogenic groups (approximately 22-25 A(2) per mesogenic group) is required. As a consequence, the monoadduct forms a bilayered smectic A phase. The supramolecular organization of the bisadducts is essentially governed by the nature and structure of the mesogenic groups and dendritic core. Therefore, the bisadducts form monolayered smectic A phases. The title compounds are promising supramolecular materials as they combine the self-organizing behavior of liquid crystals with the properties of fullerene. 相似文献
122.
María D. Hernández-Alonso Juan M. Coronado Javier Soria José Carlos Conesa Vittorio Loddo Maurizio Addamo Vincenzo Augugliaro 《Research on Chemical Intermediates》2007,33(3-5):205-224
Oxidation of free cyanide in aqueous suspensions of three commercial TiO2 specimens, with different anatase crystal size, has been carried out in a batch photoreactor by simultaneously applying ozonation and photocatalysis. Dissolved ozone participates both in homogeneous and catalytic reactions with cyanide; the extents of these two processes are comparable to that of the photodegradation with oxygen. The reactivity results are well described by the Langmuir-Hinshelwood kinetic model, providing the values of the kinetic and equilibrium adsorption constants for the catalytic and photocatalytic reactions contributing to cyanide oxidation. The cyanide concentration decreases faster with time for catalysts with increasing anatase crystal size, being more marked under UV irradiation. EPR studies on gaseous ozone adsorption on the three samples in the dark have shown stronger ozone interactions with Ti4+ and O2? ions of the samples with largest anatase crystal size, leading to the formation of significant signals of Ti3+ and s O??O2 radicals than with the anatase with the lowest crystal size, where ozone was mainly adsorbed on water molecular arrangements covering its surface. The hampering of the ozone and/or cyanide adsorption by the water molecular arrangements covering the surface of the catalyst with the lowest crystal size would justify the low cyanide degradation rate observed for this sample. 相似文献
123.
Candiano G Santucci L Petretto A Pavone B Del Boccio P Musante L Bruschi M Federici G Gusmano R Urbani A Ghiggeri GM 《Electrophoresis》2008,29(3):682-694
A 2-DE system has been devised in which proteins are first separated in their native state followed by separation according to mass under denaturing conditions (Nat/SDS-PAGE). Hydrophilic properties of the gel and the presence of dihydroxybisacrylamide in the first dimension allowed a good resolution for high-molecular-weight proteins and maintained interactions. With this method 252 plasma spots have been resolved and 140 have been characterized by MS as isoforms of 60 proteins, a relevant part of which (12) were not detected by traditional 2-D gels or by other nondenaturing 2-D techniques. The list includes complement factors (C4d, C7), coagulation factors (coagulation factor II, fibrin beta), apolipoproteins (apolipoprotein B) and cell debris (vinculin, gelsolin, tropomyosin, dystrobrevin beta, fibrinectin I). Nat/SDS PAGE also allowed separation of nicked forms of albumin, Apo B100 and alpha2-macroglobulin and showed the presence of atypical albumin adducts corresponding to post-translational and oxidation products. Our system provides therefore new tools for resolving proteins, protein aggregates and complexes and amplifies the potentiality of traditional electrophoretic analysis. 相似文献
124.
H.G. Rotstein et al. proposed a nonconserved phase-field system characterized by the presence of memory terms both in the heat conduction and
in the order parameter dynamics. These hereditary effects are represented by time convolution integrals whose relaxation kernels
k and h are nonnegative, smooth and decreasing. Rescaling k and h properly, we obtain a system of coupled partial integrodifferential equations depending on two relaxation times ɛ and σ.
When ɛ and σ tend to 0, the formal limiting system is the well-known nonconserved phase-field model proposed by G. Caginalp.
Assuming the exponential decay of the relaxation kernels, the rescaled system, endowed with homogeneous Neumann boundary conditions,
generates a dissipative strongly continuous semigroup Sɛ, σ(t) on a suitable phase space, which accounts for the past histories of the temperature as well as of the order parameter. Our
main result consists in proving the existence of a family of exponential attractors
for Sɛ, σ(t), with ɛ, σ ∈ [0, 1], whose symmetric Hausdorff distance from
tends to 0 in an explicitly controlled way. 相似文献
125.
126.
127.
Maurizio Lusignoli Silvano Petrarca 《The European Physical Journal C - Particles and Fields》2011,71(3):1568
A brief up-to-date review of the long-range forces generated by two neutrino exchange is presented. The potential due to exchange
of a massive neutrino–antineutrino pair between particles carrying weak charge might be larger than expected if the neutrinos
have not only masses but also magnetic moments close to the present experimental bounds. It still remains too small to be
observable. 相似文献
128.
129.
Massimiliano Aschi Caterina Fraschetti Antonello Filippi Maurizio Speranza 《Journal of mass spectrometry : JMS》2009,44(7):1038-1046
The nature of the ionic species, formed by electrospray ionization (ESI) of Co(NO3)2/CH3OH solutions with a pair of aminoalcohols W and Y, has been investigated by mass spectrometric and computational methods. Collision induced dissociation (CID) of ions, formally corresponding to the [WYCoNO3]+ structures, yields fragmentation patterns which reflect not only the expected [WYCoNO3]+ connectivity but also that of other isomeric structures. Formation of these latter species is observed only in the presence of a tertiary aminoalcohol, like N‐methylpseudoephedrine. The CID patterns are found to be strongly dependent on the chemical form (whether the free aminoalcohol or its hydrochloride), the configuration, and the relative concentration of the W and Y aminoalcohols. This variability parallels the results of classical MD (molecular dynamics) simulations of the [WYCoNO3]+ adducts which show a drastic alteration of the mechanical–dynamical features of the adducts by simply changing the charge state of W and/or Y, their absolute configuration, or by removing the solvent. The present experimental and computational study confirms the observation of fast stereoselective reactions in ESI nanodroplets before their evaporation and warns against any automatic correlation between the ESI spectrum of an analyte and its structure in solution. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
130.
Maurizio Negri 《Mathematical Logic Quarterly》1990,36(4):319-329