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排序方式: 共有134条查询结果,搜索用时 15 毫秒
71.
We propose a model to explain finite-size effects in intracellular microrheology observed in experiments. The constrained dynamics of the particles in the intracellular medium, treated as a viscoelastic medium, is described by means of a diffusion equation in which interactions of the particles with the cytoskeleton are modeled by a harmonic force. The model reproduces the observed power law behavior of the mean square displacement in which the exponent depends on the ratio between particle-to-cytoskeleton-network sizes. 相似文献
72.
Carmona D Balas F Mayoral Á Luque R Urriolabeitia EP Santamaría J 《Chemical communications (Cambridge, England)》2011,47(45):12337-12339
The structure of ordered mesoporous materials presenting a cubic structure undergoes a strong modification after adding aluminium alkoxides to the synthesis gel. As a result, an outstanding increase in the surface area and pore volume is observed, together with changes in the mesopore ordering. Hydrated aluminium species influence the chemical environment of the micelles during synthesis, which seems to induce the accumulation of stacking faults in the mesopore framework, and give rise to closer structural packing. The adsorption and release of ibuprofen as a test molecule correlates well with the textural changes observed. 相似文献
73.
74.
The high-pressure behaviour of cesium sulphide Cs(2)S has been studied up to 19 GPa at room temperature using angle-dispersive x-ray powder diffraction in a diamond-anvil cell. X-ray results show that the initial anticotunnite-type structure (S.G. Pnma) seems to undertake a continuous transformation to a distorted Ni(2)In-type structure (also with S.G. Pnma), starting below 1 GPa and being almost completed at 5 GPa. The profile of the x-ray diffraction patterns did not change noticeably from this pressure to 17 GPa. The observed structural changes in Cs(2)S are discussed in relation to the high-pressure behaviour of the rest of alkaline sulfides and their systematic trends are pointed out. Finally, we discuss the analogies between the structures of alkaline-metal chalcogenides and those of the cationic arrays of their corresponding oxides (sulfates, selenates, and tellurates) comparing the insertion of oxygen and the application of pressure. 相似文献
75.
Isabel Villar David J. Suarez-De la Calle Zoraida González Marcos Granda Clara Blanco Rosa Menéndez Ricardo Santamaría 《Adsorption》2011,17(3):467-471
Different porous carbons (MWCNT, a carbon aerogel, an activated carbon cloth and a chemically activated carbon) were evaluated
as electrode material for the electrosorption of NaCl. The results obtained from the chronoamperometric experiments were correlated
to the surface area and the size of the pores present in each carbon. These results indicate that all the surfaces are equivalent
for the electrosorption process, demonstrating that both, mesopores and micropores, are equally effective. Nevertheless, the
kinetics of the process is influenced by the pore size distribution of the carbon, although it is rather fast for all the
carbons studied. The chemically activated carbon seems to be the most suitable carbon material for electrosorption of NaCl
due to the combination of a high surface area and an appropriate pore size distribution. 相似文献
76.
Pedro A. Martínez Martínez V. Fernandez Escartïn T. Pollán Santamaría 《International Journal of Mathematical Education in Science & Technology》2013,44(6):747-748
A new method for the analysis of sinusoidal oscillators, based on a general characterization of feedback electronic systems, is drawn. This exact and algorithmic method allows us to find the oscillation conditions by the calculation of only one transfer function of a circuit which, generally, is obtained by a simple inspection of the system. 相似文献
77.
Aurora Pacini Marco Caricato Stefania Ferrari Doretta Capsoni Antxon Martínez de Ilarduya Sebastián Muñoz‐Guerra Dario Pasini 《Journal of polymer science. Part A, Polymer chemistry》2012,50(22):4790-4799
We report on a series of novel poly(γ‐glutamic acid) (PGGA) esters, in which the chemical structure and composition, and the molecular weight are systematically changed. Modification of PGGA of microbial origin, used either as the sodium salt or in the free acid form, by means of alkylation with highly reactive bromides under SN2 conditions, affords copolymers with an essentially random microstructure. These reaction conditions are applied iteratively to achieve full esterification, obtaining allyl or propargyl ester functionalities within the polymer backbone, diluted with inert functional groups, such as benzyl, ethyl, or hexyl ester functionalities. The copolymers have been characterized regarding their chemical structure and thermal and bulk properties using nuclear magnetic resonance, thermogravimetry, differential scanning calorimetry, and X‐ray diffraction techniques. We demonstrate that allyl and propargyl ester groups can be efficiently transformed using click chemistries, such as thiol‐ene or copper(I)‐catalyzed azide–alkyne cycloaddition reactions; such efficient conjugation strategies will be required to transform the native bacterial biopolymer into a material with tailored properties for bulk scale or biomedical applications. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
78.
Montserrat García-Alvarez Antxon Martínez de Ilarduya José Antonio Portilla Abdelilah Alla Sebastián Muñoz-Guerra 《Macromolecular Symposia》2008,273(1):85-94
Summary: Stoichiometric complexes of biotechnological poly(γ-glutamic) acid and poly(β,L -malic) acid with alkyltrimethylammonium surfactants of long alkyl chains could be readily prepared in aqueous medium. They adopt a biphasic layered structures in which the main chain and the side chain alternate with nanometric periodicity. Alkyl side chains show reversible melting that involves generation of mesophases. Complexes degraded by water by different mechanisms depending on the constitution of the main chain; the polymalic complexes underwent surface erosion whereas the polyglutamic ones degraded in bulk. Erythromycin could be homogenously loaded into the paraffinic subphase of the complexes and delivered upon incubation under physiological conditions in parallel to the hydrolysis of the polymer. 相似文献
79.
Hoffmann A Nieva G Guimpel J Bruynseraede Y Santamaría J Lederman D Schuller IK 《Physical review letters》2006,97(11):119701; author reply 119702
80.
León C Rivera A Santamaría J Moynihan CT Ngai KL 《Physical review letters》2002,89(7):079601; author reply 079602