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991.
Cristina Fernandez‐Barranco Africa Yebra‐Rodriguez M. Dolores La Rubia‐Garcia Francisco J. Navas‐Martos Pedro Alvarez‐Lloret 《Polymer Composites》2015,36(12):2326-2333
Polyamide66 (PA66) and polyamide66/sepiolite (PA66/sepiolite) nanocomposites at 1, 3, 5, 7, and 9 wt% clay loading were prepared and injected to simulate industrial processing. Tensile tests were performed in the samples, and scanning electron microscopy was used to characterize the fracture surface. The samples were also examined by X‐ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), and vibrational spectroscopy analysis (FT‐IR and FT‐Raman). Higher tensile strength and stiffness and reduction of the strain to failure are observed in the nanocomposites with higher sepiolite content. Two‐dimensional XRD analyses show that the sepiolite also enhances the orientation of PA66 crystals. XRD and spectroscopic analyses corroborate that the nanoclay fibers are placed between the lamellar superstructure of the PA66 without affecting the polymer chains. DSC confirms that the presence of sepiolite does not influence the crystallinity nor the nucleation of PA66 as the arrangement of the fibers between the PA66 lamellae hinders the nucleation of new crystals. We propose a model for the crystallographic organization of the organic and inorganic phases in the PA66/sepiolite nanocomposites. POLYM. COMPOS., 36:2326–2333, 2015. © 2014 Society of Plastics Engineers 相似文献
992.
Fortuna L. La Rosa M. Nicolosi D. Porto D. 《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》2004,12(11):1167-1173
In this paper, we consider coupled quantum-dot cells, which are usually used for quantum-dot cellular automata, to build nanoscale dynamical systems. In particular, it is shown how the simple connection of few quantum-dot cells, quantum cellular nonlinear networks (Q-CNNs), can cause the onset of chaotic oscillations. Complex dynamics can be obtained only with small differences of polarizations and parameters. Local activity conditions are investigated for a two-cells case satisfying the criteria for the generation of complex spatio-temporal behaviors. The richness of dynamics of quantum CNNs is also emphasized through examples of synchronization in an array of so-built oscillators, in both cases of identical parameters and spatial dissymmetry. 相似文献
993.
C Rodriguez-Esteban JW Schwabe J De La Pe?a B Foys B Eshelman JC Izpisúa Belmonte 《Canadian Metallurgical Quarterly》1997,386(6623):360-366
Vertebrate limb outgrowth requires a structure called the apical ectodermal ridge, formation of which follows the previous establishment of the dorsoventral limb axis. Radical fringe is expressed in the dorsal ectoderm before the ridge appears, and is repressed by Engrailed-1, which is expressed in the ventral ectoderm. Misexpression of these genes indicates that a ridge is formed wherever there is a boundary between cells expressing and not expressing Radical fringe. Thus, as in Drosophila, Radical fringe positions the ridge at the dorsoventral limb boundary. 相似文献
994.
Light Leah L.; Kennison Robert; Prull Matthew W.; La Voie Donna; Zuelling Andrea 《Canadian Metallurgical Quarterly》1996,11(3):417
In this article, three experiments in which single-trial associative priming for nonwords was investigated in young and older adults in a pronunciation task are reported. During an encoding task, associative priming was observed for young and older adults, although cued recall was near zero for both groups. Associative priming for young and older adults was found under full attention conditions, but when attention was divided at study, associative priming was observed in Experiment 3, but not in Experiment 2. Divided attention also disrupted recognition memory for new associations in young and older adults. The results limit the generality of findings of age-related decrements in associative priming by showing an absence of such decrements in tasks that do not require elaborative processing during encoding. They also argue against G. Musen and L. Squire's (see record 1993-34212-001) suggestion that formation of new connections in implicit memory requires multiple study opportunities, whereas declarative memory is specialized for rapid acquisition of new associations. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
995.
Chlorinated polyesters were synthesized from the following acid di-chlorides: 2,3,5,6-tetrachloro-1,4-terephthaloyl ( I ), 2,3,5,6-tetrachloro-1,4-phenylenediacetyl ( II ), and 2,3,5,6-tetrachloro-1,4-phenylenedi(oxyacetyl) ( III ), and bisphenol A, under phase transfer conditions, using several ammonium and phosphonium salts as catalysts and a biphasic CH2Cl2/NaOH system. The influence of the nature of the catalysts and the reaction times were evaluated by the yields and ηinh of the polyesters. The reactivity of the monomers was I < II < III , due to the smaller influence of the tetrachlorinated ring when there is a spacer group between the aromatic ring and the acid chloride group. 相似文献
996.
997.
Location based services(LBS) are becoming increasingly important to the success and attractiveness of next generation wireless systems. However, a natural tension arises between the need for user privacy and the flexible use of location information. In this paper we present a framework to support privacy enhanced location based services. We classify the services according to several basic criteria and we propose a hierarchical key distribution method to support these services. The key idea behind the system is to hierarchically encrypt location information under different keys, and distribute the appropriate keys only to group members with the necessary permission. Four methods are proposed to deliver hierarchical location information while maintaining privacy. We propose a key tree rebalancing algorithm to maintain the re-keying performance of the group key management. Furthermore, we present a practical LBS system implementation. Hierarchical location information coding offers flexible location information access which enables a rich set of location based services. Our load tests show such a system is highly practical with good efficiency and scalability. 相似文献
998.
Antonio Vega-Gálvez Eduardo Notte-Cuello Roberto Lemus-Mondaca Liliana Zura Margarita Miranda 《Food and Bioproducts Processing》2009,87(4):254-260
Aloe vera (Aloe barbadensis Miller) slabs dried at 60 °C were rehydrated at three temperatures (20, 40 and 60 °C) in order to study the influence of temperature on the kinetics of mass transfer during rehydration phenomenon. Fick, Peleg and Weibull models were applied for rehydration modelling, as well as one new proposed model. All kinetic parameters of the models showed positive dependence on temperature, according to the Arrhenius-type equation. Weibull model and the new proposed model provided the best fit quality for each rehydration curve based on the statistical tests RMS, SSE and Chi-square. In accordance with the results, both models may be used to estimate the rehydration time of A. vera. Furthermore, two rehydration indices (RR and WHC) were analysed, which decreased as temperature increased. These indices confirm that drying process modifies the cell structure of A. vera, reducing the rehydration ability due to cellular and structural disruption that takes place during dehydration. 相似文献
999.
1000.