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991.
Hendrik Heinz Chandrani Pramanik Ozge Heinz Yifu Ding Ratan K. Mishra Delphine Marchon Robert J. Flatt Irina Estrela-Lopis Jordi Llop Sergio Moya Ronald F. Ziolo 《Surface Science Reports》2017,72(1):1-58
Nanostructures of diverse chemical nature are used as biomarkers, therapeutics, catalysts, and structural reinforcements. The decoration with surfactants has a long history and is essential to introduce specific functions. The definition of surfactants in this review is very broad, following its lexical meaning “surface active agents”, and therefore includes traditional alkyl modifiers, biological ligands, polymers, and other surface active molecules. The review systematically covers covalent and non-covalent interactions of such surfactants with various types of nanomaterials, including metals, oxides, layered materials, and polymers as well as their applications. The major themes are (i) molecular recognition and noncovalent assembly mechanisms of surfactants on the nanoparticle and nanocrystal surfaces, (ii) covalent grafting techniques and multi-step surface modification, (iii) dispersion properties and surface reactions, (iv) the use of surfactants to influence crystal growth, as well as (v) the incorporation of biorecognition and other material-targeting functionality. For the diverse materials classes, similarities and differences in surfactant assembly, function, as well as materials performance in specific applications are described in a comparative way. Major factors that lead to differentiation are the surface energy, surface chemistry and pH sensitivity, as well as the degree of surface regularity and defects in the nanoparticle cores and in the surfactant shell. The review covers a broad range of surface modifications and applications in biological recognition and therapeutics, sensors, nanomaterials for catalysis, energy conversion and storage, the dispersion properties of nanoparticles in structural composites and cement, as well as purification systems and classical detergents. Design principles for surfactants to optimize the performance of specific nanostructures are discussed. The review concludes with challenges and opportunities. 相似文献
992.
SergioAmat SoniaBusquier VicenteF.Candela 《计算数学(英文版)》2004,22(1):1-10
An alternative to the classical extrapolations is proposed. The stability and the accuracy are studied. The new extrapolation behaves better than the classical ones when there are problems of stability. This technique will be useful in those problems where the region of stability is very small and it forces to work with too fine scales. 相似文献
993.
Sergio A. Oliveira Marcelo A. Savi Alexander L. Kalamkarov 《Archive of Applied Mechanics (Ingenieur Archiv)》2010,80(10):1163-1175
Shape memory alloys (SMAs) are materials that, among other characteristics, have the ability to present high deformation levels
when subjected to mechanical loading, returning to their original form after a temperature change. Literature presents numerous
constitutive models that describe the phenomenological features of the thermomechanical behavior of SMAs. The present paper
introduces a novel three-dimensional constitutive model that describes the martensitic phase transformations within the scope
of standard generalized materials. The model is capable of describing the main features of the thermomechanical behavior of
SMAs by considering four macroscopic phases associated with austenitic phase and three variants of martensite. A numerical
procedure is proposed to deal with the nonlinearities of the model. Numerical simulations are carried out dealing with uniaxial
and multiaxial single-point tests showing the capability of the introduced model to describe the general behavior of SMAs.
Specifically, uniaxial tests show pseudoelasticity, shape memory effect, phase transformation due to temperature change and
internal subloops due to incomplete phase transformations. Concerning multiaxial tests, the pure shear stress and hydrostatic
tests are discussed showing qualitatively coherent results. Moreover, other tensile–shear tests are conducted modeling the
general three-dimensional behavior of SMAs. It is shown that the multiaxial results are qualitative coherent with the related
data presented in the literature. 相似文献
994.
The modeling of the elastoplastic behaviour of single crystals with infinite latent hardening leads to a nonconvex energy density, whose minimization produces fine structures. The computation of the quasiconvex envelope of the energy density is faced in this case with huge numerical difficulties caused by the clusters of local minima. By exploiting the structure of the problem, we present a fast and efficient numerical relaxation algorithm as alternative to global optimization techniques usually adopted in literature which are computationally more expensive. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
995.
Sandra Rojas-Lema Jordi Arevalo Jaume Gomez-Caturla Daniel Garcia-Garcia Sergio Torres-Giner 《Molecules (Basel, Switzerland)》2021,26(19)
Framing the Circular Bioeconomy, the use of reactive compatibilizers was applied in order to increase the interfacial adhesion and, hence, the physical properties and applications of green composites based on biopolymers and food waste derived lignocellulosic fillers. In this study, poly(butylene succinate) grafted with maleic anhydride (PBS-g-MAH) was successfully synthetized by a reactive melt-mixing process using poly(butylene succinate) (PBS) and maleic anhydride (MAH) that was induced with dicumyl peroxide (DCP) as a radical initiator and based on the formation of macroradicals derived from the hydrogen abstraction of the biopolymer backbone. Then, PBS-g-MAH was used as reactive compatibilizer for PBS filled with different contents of pistachio shell flour (PSF) during melt extrusion. As confirmed by Fourier transform infrared (FTIR), PBS-g-MAH acted as a bridge between the two composite phases since it was readily soluble in PBS and could successfully form new esters by reaction of its multiple MAH groups with the hydroxyl (–OH) groups present in cellulose or lignin of PSF and the end ones in PBS. The resultant compatibilized green composites were, thereafter, shaped by injection molding into 4-mm thick pieces with a wood-like color. Results showed significant increases in the mechanical and thermomechanical rigidity and hardness, meanwhile variations on the thermal stability were negligible. The enhancement observed was related to the good dispersion and the improved filler-matrix interfacial interactions achieved by PBS-g-MAH and also to the PSF nucleating effect that increased the PBS’s crystallinity. Furthermore, water uptake of the pieces progressively increased as a function of the filler content, whereas the disintegration in controlled compost soil was limited due to their large thickness. 相似文献
996.
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998.
Dealing with long‐range interactions in the determination of polyelectrolyte ionization properties. Extension of the transfer matrix formalism to the full range of ionic strengths 下载免费PDF全文
999.
Ring opening metathesis polymerization of triazole‐bearing cyclobutenes: Diblock copolymer synthesis and evaluation of the effect of side group size on polymerization kinetics 下载免费PDF全文
Jia Wei William Trout Yoan C. Simon Sergio Granados‐Focil 《Journal of polymer science. Part A, Polymer chemistry》2017,55(11):1929-1939
Cyclobutenes containing pendant groups of varying sizes were polymerized via ring opening metathesis polymerization using Grubbs catalyst 2nd generation (G2). The rate of polymerization depended on the size of the pendant groups attached to the cyclobutene rings, with longer side‐chains producing slower polymerization rates and narrower molecular weight distributions. The polymerization of these new molecules proceeded with first order kinetics, consistent with a living polymerization. Chain extension experiments produced cyclobutene‐based diblock copolymers with polydispersity indices below 1.33. The synthetic methods in this report will allow the use of G2 to access new complex polymeric architectures with a higher density of pendant groups than those derived from norbornene analogs and cyclooctene moieties. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1929–1939 相似文献
1000.