Search results for "FISICA APLICADA"
showing 10 items of 316 documents
Pressure effects on the vibrational properties of alpha-Bi2O3: an experimental and theoretical study
2014
We report an experimental and theoretical high-pressure study of the vibrational properties of synthetic monoclinic bismuth oxide (alpha-Bi2O3), also known as mineral bismite. The comparison of Raman scattering measurements and theoretical lattice-dynamics ab initio calculations is key to understanding the complex vibrational properties of bismite. On one hand, calculations help in the symmetry assignment of phonons and to discover the phonon interactions taking place in this low-symmetry compound, which shows considerable phonon anticrossings; and, on the other hand, measurements help to validate the accuracy of first-principles calculations relating to this compound. We have also studied …
Multiproject–multicenter evaluation of automatic brain tumor classification by magnetic resonance spectroscopy
2008
[EN] Automatic brain tumor classification by MRS has been under development for more than a decade. Nonetheless, to our knowledge, there are no published evaluations of predictive models with unseen cases that are subsequently acquired in different centers. The multicenter eTUMOUR project (2004-2009), which builds upon previous expertise from the INTERPRET project (2000-2002) has allowed such an evaluation to take place. A total of 253 pairwise classifiers for glioblastoma, meningioma, metastasis, and low-grade glial diagnosis were inferred based on 211 SV short TE INTERPRET MR spectra obtained at 1.5 T (PRESS or STEAM, 20-32 ms) and automatically pre-processed. Afterwards, the classifiers …
Temporal variability analysis reveals biases in electronic health records due to hospital process reengineering interventions over seven years
2019
[EN] Objective To evaluate the effects of Process-Reengineering interventions on the Electronic Health Records (EHR) of a hospital over 7 years. Materials and methods Temporal Variability Assessment (TVA) based on probabilistic data quality assessment was applied to the historic monthly-batched admission data of Hospital La Fe Valencia, Spain from 2010 to 2016. Routine healthcare data with a complete EHR was expanded by processed variables such as the Charlson Comorbidity Index. Results Four Process-Reengineering interventions were detected by quantifiable effects on the EHR: (1) the hospital relocation in 2011 involved progressive reduction of admissions during the next four months, (2) th…
Asymmetric nanopore rectification for ion pumping, electrical power generation, and information processing applications
2011
Single-track, asymmetric nanopores can currently be functionalised with a spatially inhomogeneous distribution of fixed charges and a variety of pore tip shapes. Optimising the asymmetric nanopore characteristics is crucial for practical applications in nanofluidics. We have addressed here this question for three cases based on different input/output chemical and electrical signals: (i) ion pumping up a concentration gradient by means of a periodic, time-dependent bias potential, (ii) information processing with a single nanopore acting as the nanofluidic diode of a logic gate, and (iii) electrical energy harvesting using a nanopore that separates two solutions of different salt concentrati…
Biomolecular conjugation inside synthetic polymer nanopores via glycoprotein-lectin interactions
2011
We demonstrate the supramolecular bioconjugation of concanavalin A (Con A) protein with glycoenzyme horseradish peroxidase (HRP) inside single nanopores, fabricated in heavy ion tracked polymer membranes. Firstly, the HRP-enzyme was covalently immobilized on the inner wall of the pores using carbodiimide coupling chemistry. The immobilized HRP-enzyme molecules bear sugar (mannose) groups available for the binding of Con A protein. Secondly, the bioconjugation of Con A on the pore wall was achieved through its biospecific interactions with the mannose residues of the HRP enzyme. The immobilization of biomolecules inside the nanopore leads to the reduction of the available area for ionic tran…
Broadband, site selective and time resolved photoluminescence spectroscopic studies of finely size-modulated Y2O3:Eu3+ phosphors synthesized by a com…
2014
Undoped and Eu3+-doped cubic yttria (Y2O3) nanophosphors of good crystallinity, with selective particle sizes ranging between 6 and 37 nm and showing narrow size distributions, have been synthesized by a complex-based precursor solution method. The systematic size tuning has been evidenced by transmission electron microscopy, X-ray diffraction, and Raman scattering measurements. Furthermore, size-modulated properties of Eu3+ ions have been correlated with the local structure of Eu3+ ion in different sized Y2O3:Eu3+ nanophosphors by means of steady-state and time-resolved site-selective laser spectroscopies. Time-resolved site-selective excitation measurements performed in the 7F0 ¿ 5D0 peak…
Energy conversion from external fluctuating signals based on asymmetric nanopores
2015
Electrical transduction from fluctuating external signals is central to energy conversion based on nanoscale electrochemical devices and bioelectronics interfaces. We demonstrate theoretically and experimentally a significant energy transduction from white noise signals using the electrical rectification of asymmetric nanopores in polymeric membranes immersed in aqueous electrolyte solutions. Load capacitor voltages of the order of 1 V are obtained within times of the order of 1 min by means of nanofluidic diodes which convert zero time-average potentials of amplitudes of the order of 1 V into average net currents. We consider single-nanopore and multipore membranes to show that the convers…
Electrical network of nanofluidic diodes in electrolyte solutions: Connectivity and coupling to electronic elements
2016
[EN] We consider a nanopore network with simple connectivity, demonstrating a two-dimensional circuit (full-wave rectifier) with ensembles of conical pores acting as nanofluidic diodes. When the bridge nanopore network is fed with an input potential signal of fluctuating polarity, a fixed output polarity is obtained. The full-wave rectification characteristics are demonstrated with square, sinusoidal, and white noise input waveforms. The charging of a load capacitor located between the two legs of the bridge demonstrates that the nanofluidic network is effectively coupled to this electronic element. These results can be relevant for energy transduction and storage procedures with nanopores …
Single cigar-shaped nanopores functionalized with amphoteric amino acid chains: experimental and theoretical characterization.
2012
We present an experimental and theoretical characterization of single cigar-shaped nanopores with pH-responsive carboxylic acid and lysine chains functionalized on the pore surface. The nanopore characterization includes (i) optical images of the nanostructure obtained by FESEM; (ii) different chemical procedures for the nanopore preparation (etching time and functionalizations; pH and electrolyte concentration of the external solution) allowing externally tunable nanopore responses monitored by the current-voltage (I-V) curves; and (iii) transport simulations obtained with a multilayer nanopore model. We show that a single, approximately symmetric nanopore can be operated as a reconfigurab…
Current rectification by nanoparticle blocking in single cylindrical nanopores.
2014
Blocking of a charged pore by an oppositely charged nanoparticle can support rectifying properties in a cylindrical nanopore, as opposed to the usual case of a fixed asymmetry in the pore geometry and charge distribution. We present here experimental data and model calculations to confirm this fundamental effect. The nanostructure imaging and the effects of nanoparticle concentration, pore radius, and salt concentration on the electrical conductance–voltage (G–V) curves are discussed. Logic responses based on chemical and electrical inputs/outputs could also be implemented with a single pore acting as an effective nanofluidic diode. To better show the generality of the results, different ch…