A5007703368- Liquid Crystal Research Advancements
- Molecular spectroscopy and chirality
- Experimental and Theoretical Physics Studies
- Material Dynamics and Properties
- Experimental Learning in Engineering
- Nonlinear Dynamics and Pattern Formation
- Sports Dynamics and Biomechanics
- Model Reduction and Neural Networks
- Surfactants and Colloidal Systems
- Synthesis and Properties of Aromatic Compounds
- Photoreceptor and optogenetics research
- Computational Physics and Python Applications
- Chemical and Physical Properties of Materials
- Graphene research and applications
- Muscle activation and electromyography studies
- Various Chemistry Research Topics
- Plant Reproductive Biology
- Advanced NMR Techniques and Applications
- Neuroscience and Neural Engineering
- Spectroscopy and Quantum Chemical Studies
- Mechanical and Optical Resonators
- Photonic Crystals and Applications
- Carbon Nanotubes in Composites
University of Lisbon
2014-2022
Instituto Politécnico de Lisboa
2006-2022
Instituto de Engenharia de Sistemas e Computadores Investigação e Desenvolvimento
1999-2017
Instituto Superior Técnico
1997-2010
University of Oxford
1979
Abstract It is proposed that the liquid phase metal-non metal transition in carbon takes place between an sp hybridized non-metallic liquid, with coordination number two, and a strongly correlated which directional bonding remains important though hybridization will probably change. Only at higher pressures quadrivalent to be expected, formation of should occur known maximum melting line graphite. Motivated by phenomenological argument, possible experiments clarify nature these different...
Oscillatory motion is a main topic in physics at all levels of undergraduate courses. In this work, we study the damping bar acting as physical pendulum subjected to air drag.
A basic setup for data acquisition and analysis from an oscillatory circuit is described, with focus on its application as either low-pass, high-pass, band-pass or band-reject frequency filter. homemade board containing the RLC elements allows interchange of some them, in particular, easy change R value, this makes apparent student influence damping factor. The function generator operates swap mode over a suitable range all parameters are chosen to provide reasonable set electronic filters...
A detailed analysis of three pendular motion models is presented. Inertial effects, self-oscillation, and memory, together with non-constant moment inertia, hysteresis negative damping are shown to be required for the comprehensive description free pendulum oscillatory regime. The effects very high initial amplitudes, friction in roller bearing axle, drag, geometry also analysed discussed. model that consists a fractional differential equation provides both best explanation of, fits to,...
A self-consistent analysis of proton and deuterium nuclear spin relaxation times in the smectic phases a partially deuterated smectogen is presented here. Proton spin-lattice T(1Z) were measured as function Larmor frequency over range 1 kHz to 300 MHz at selected temperatures. Deuterium T(1Q) temperature two different magnetic fields phase. The data provide dynamic parameters such rotational diffusion constants internal jump rates well nematic order parameter S. are analyzed using number...
This study reports deuterium nuclear-magnetic-resonance (NMR) spectra collected at 61.4MHz in the chiral smectic- C phase of liquid crystal 4{'}(octyloxy)-d{17} biphenyl-4- yl2 -chloro-3-methylpentanoate (BP8Cl). By using a goniometer probe, oriented sample was rotated to collect different rotation (theta) angles. These were simulated gain information on solitonlike distortions helical superstructure. The Landau theory adopted distortion helix by NMR magnetic field. Deuterium two-dimensional...
Abstract Advanced fitting of ordinary differential equations models to experimental results is presented within the context different academic levels students and diverse research fields. In many areas, analysis cannot be restricted cases where particular solutions models’ equations, valid only for specific limit conditions, apply. those cases, analytical mathematical are not available a complete description systems extends beyond numerical minimization statistical estimators, like...
Abstract Proton spin-lattice relaxation studies were carried out in the SA and S*C phases of liquid crystal CI IPNOC using both conventional fast field cycling NMR techniques. T 1 dispersion curves obtained at two different temperatures for each mesophase covering frequencies from 102 to 3 × 108 Hz. In mesophases data can be described assuming presence three mechanisms, namely local molecular rotations, self-diffusion collective motions. The constant D was evaluated several activation energy...
We report the first study of1nolecular dynaInics in a TGBA Inesophase, by Ineans of proton NMR relaxation, liquid crystal coInpound that exhibits and Sl Inesophases.The relaxation dispersion detected S[ phase is siInilar to those observed JOURNAL DE PHYSIQUE II N°1 1.
Hydroxypropylcellulose films are used as the alignment substrate in a liquid crystal bistable electro-optical device. These were characterized by atomic force microscopy. The behaviour of this device, which operates Clark-Lagerwall mode, is identical to that observed for typical SSFLC cells. In particular bistability cell was clearly observed, threshold voltage measured and an estimation anchoring energy LC mixture used, type system, made.
Abstract We report the first study of molecular dynamics in S*Cγ (ferrielectric) and S*CA (anti-ferroelectric) mesophases a liquid crystal, by means proton NMR relaxation. The relaxation dispersion detected both is compared with observed for SA S*C phases same compound, which similar to those previous studies. However, describe behaviour we had include an additional mechanism. Considering frequency range where it observed, this mechanism may be related antiphase azimuihal mode previously...
A power supply with potential use in the magnetic stimulation of biological systems is presented this paper. The effect depends on geometry and orientation induced electric field, as well current pulse waveform delivered by stimulator (coil). These factors are very important to define equipment requirements characteristics, namely topology size coil. proposed solution able generate pulses variable amplitude duration, according a user- defined input. main characteristics working principle,...
Abstract Molecular dynamics studies were carried out in the S A and * C mesophases of Ferroelectric Liquid Crystal Val.DOC by means longitudinal proton spin relaxation dispersion. Fast field-cycling conventional Nuclear Magnetic Resonance (NMR) techniques used to obtain frequency dependence T 1 covering frequencies from 102 3 × 108 Hz at two different temperatures each mesophase. The dispersion both could be well modeled proposed dominant mechanisms, namely collective motions, molecular self...