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141.
Nanostructure development in nylon 6-Cloisite® 30B composites. Effects of the preparation conditions
Massimo Paci 《European Polymer Journal》2010,46(5):838-853
PA6 composites with Cloisite® 30B (30B), prepared by different procedures, i.e., melt compounding, static annealing and solution blending, have been characterized by X-ray diffraction and microscopic analyses (TEM, SEM, POM) in order to shed more light on the mechanism of nanostructure development. It has been demonstrated that intercalation of the PA6 chains within the 30B galleries takes place very rapidly, in the absence of applied stresses, even when the size of the clay particles is relatively large (tens of microns) and the clay loading is very high (even 50 wt.%). It has also been shown that, if, conversely, the filler content is low (∼10 wt.% or less) and the particles are tiny (e.g., as for polymer/clay mixtures prepared by precipitation from a common solution), intercalation continues, under quiescent conditions, and leads in reasonable times to complete destruction of the silicate platelets stacking order. The composites with higher filler contents display a mixed exfoliated/intercalated morphology, with the intercalated silicate stacks characterized by an interlayer distance of about 3.7 nm. Contrary to statically annealed composites, the melt kneaded ones are characterized by a homogeneous dispersion of the filler particles and a local parallel orientation of the silicate platelets that induces, during polymer crystallization, an orientation of the polymer crystallites parallel to the faces of the compression molded specimens. Experiments carried out using 30B samples previously treated at 250 °C for 4 h under vacuum (30Bdegr) indicate that this treatment, probably due to the collapsed interlayer spaces, lowers the extent of PA6 chains intercalation. Thus, the relevant PA6/30Bdegr composites are characterized by the coexistence of unintercalated clay tactoids/agglomerates and individual silicate layers formed as result of intercalation on the edges of the filler particles. 相似文献
142.
Massimo Bietti Alessandra Calcagni Daniel Oscar Cicero Roberto Martella Michela Salamone 《Tetrahedron letters》2010,51(31):4129-1537
A product study on the reactivity of a 1,1-diarylalkoxyl radical bearing 2,2-diphenylcyclopropyl groups in the para-positions has been carried out. The exclusive formation of a product deriving from cyclopropyl ring-opening has been observed, indicating that 1,1-diarylalkoxyl radicals exist in equilibrium with a bridged 1-oxaspiro[2,5]octadienyl radical. This represents the first experimental evidence in support of the stepwise nature of the O-neophyl rearrangement of 1,1-diarylalkoxyl radicals. 相似文献
143.
Cristina Tortolini Massimo Di Fusco Marco Frasconi Gabriele Favero Franco Mazzei 《Microchemical Journal》2010,96(2):301-307
Bioelectrochemical properties of Trametes versicolor Laccase (TvL) and Trametes hirsuta Laccase (ThL) immobilized by using polyazetidine prepolymer (PAP) onto multi-walled carbon nanotubes (MWCNTs) screen printed electrode (SPE) surface, have been studied with several redox mediators by cyclic voltammetry (CV). The efficient entrapment of laccase in the PAP layer was confirmed by determination of both kinetic parameters (maximum current and Michaelis–Menten apparent constant) and analytical performances by chronoamperometry. The Laccase-modified MWCNTs electrode provides an effective biosensor for determination of polyphenols and catecholamines in real matrices; performances of the considered biosensors for real samples analysis are also compared and discussed. 相似文献
144.
This short review describes a breakthrough provided by the synthesis of d6 metal complexes containing the intact molecules P4 and P4S3. The coordinated cage molecules acquire unexpected reactivity and undergo dismutation reactions in mild conditions in the presence of water. The outcomings are obtained either in form of free or coordinated molecules; the former are hypophosphorous and phosphorous acids, the latter comprise, besides phosphine, PH3, such species as thiophosphinous acid, PH2SH, diphosphane, P2H4, 1-hydroxytriphosphane, PH(OH)PHPH2 and 1,1,4-tris-hydroxytetraphosphane, P(OH)2PHPHPH(OH), which are either unknown or extremely reactive as free molecules. The formation of the above molecules provides a clue to the hydrolytic activation of the P4 and P4S3 cage molecules. 相似文献
145.
Antonella De Palma Antonella Roveri Mattia Zaccarin Louise Benazzi Simone Daminelli Giorgia Pantano Mauro Buttarello Fulvio Ursini Massimo Gion Pier Luigi Mauri 《Journal of chromatography. A》2010,1217(33):5328-5336
Since red blood cells (RBCs) lack nuclei and organelles, cell membrane is their main load-bearing component and, according to a dynamic interaction with the cytoskeleton compartment, plays a pivotal role in their functioning. Even if erythrocyte membranes are available in large quantities, the low abundance and the hydrophobic nature of cell membrane proteins complicate their purification and detection by conventional 2D gel-based proteomic approaches. So, in order to increase the efficiency of RBC membrane proteome identification, here we took advantage of a simple and reproducible membrane sub-fractionation method coupled to Multidimensional Protein Identification Technology (MudPIT). In addition, the adoption of a stringent RBC filtration strategy from the whole blood, permitted to remove exhaustively contaminants, such as platelets and white blood cells, and to identify a total of 275 proteins in the three RBC membrane fractions collected and analysed. Finally, by means of software for the elaboration of the great quantity of data obtained and programs for statistical analysis and protein classification, it was possible to determine the validity of the entire system workflow and to assign the proper sub-cellular localization and function for the greatest number of the identified proteins. 相似文献
146.
Agnes Voitl Alessandro Butté Massimo Morbidelli 《Journal of chromatography. A》2010,1217(34):5492-5500
Experiments with human serum albumin on a strong cation exchange resin exhibit a peculiar elution pattern: the protein elutes with two peaks in a modifier gradient. This behavior is modeled with a general rate model, where the two elution peaks are modeled with two binding conformations, one of which is at equilibrium conditions, while for the other, the adsorption process is rate limited. Isocratic experiments under nonadsorbing conditions were used to characterize the mass transfer process. The isotherm of both adsorption conformations as well as the kinetic of adsorption and desorption for the second conformation are functions of the modifier concentration. They are evaluated with linear modifier gradient experiments and step experiments with various adsorption times. All experimental features are well reproduced by the proposed modified general rate model. 相似文献
147.
Ayers J Apetre N Ruzzene M Sabra K 《The Journal of the Acoustical Society of America》2011,129(2):585-588
A single head scanning laser Doppler vibrometer is used for the estimation of the polarization of the first symmetric (S(0)) and antisymmetric (A(0)) Lamb wave modes. The measurements at two known incidence angles are performed in order to resolve the two components of motion. Filtering in the frequency/wavenumber domain of the response recorded along a scan line separates the contributions from each mode and allows the evaluation of the corresponding elliptical trajectories of particle motion. Comparison between measured and analytically estimated trajectories validates the measurement technique and suggests its application for the development of material characterization and diagnostics tools. 相似文献
148.
A frequency selective acoustic transducer (FSAT) is proposed for directional sensing of guided waves. The considered FSAT design is characterized by a spiral configuration in wavenumber domain, which leads to a spatial arrangement of the sensing material producing output signals whose dominant frequency component is uniquely associated with the direction of incoming waves. The resulting spiral FSAT can be employed both for directional sensing and generation of guided waves, without relying on phasing and control of a large number of channels. The analytical expression of the shape of the spiral FSAT is obtained through the theoretical formulation for continuously distributed active material as part of a shaped piezoelectric device. Testing is performed by forming a discrete array through the points of the measurement grid of a scanning laser Doppler vibrometer. The discrete array approximates the continuous spiral FSAT geometry, and provides the flexibility to test several configurations. The experimental results demonstrate the strong frequency dependent directionality of the spiral FSAT and suggest its application for frequency selective acoustic sensors, to be employed for the localization of broadband acoustic events, or for the directional generation of Lamb waves for active interrogation of structural health. 相似文献
149.
P. Castorina D. E. Miller H. Satz 《The European Physical Journal C - Particles and Fields》2011,71(6):1673
We consider deconfined matter in SU(N) gauge theory as an ideal gas of transversely polarized quasi-particle modes having a temperature-dependent mass m(T). Just above the transition temperature, the mass is assumed to be determined by the critical behavior of the energy density
and the screening length in the medium. At high temperature, it becomes proportional to T as the only remaining scale. The resulting (trace anomaly based) interaction measure Δ=(ϵ−3P)/T
4 and energy density are found to agree well with finite temperature SU(3) lattice calculations. 相似文献
150.
Marcella Reale Antonia Patruno Maria A De Lutiis Mirko Pesce Mario Felaco Massimo Di Giannantonio Marta Di Nicola Alfredo Grilli 《BMC neuroscience》2011,12(1):13