Prof. Antônio M. Figueiredo Neto Profile

Prof. Antônio M. Figueiredo Neto

Professor at Univ de Sao Paulo

SPIE Involvement:

Conference Program Committee | Author | Editor

Proceedings Article | 3 October 2022 Presentation

Structure and local order of lyotropic cholesteric calamitic phases: the effect of the chiral molecule (Conference Presentation)

Antônio Figueiredo Neto, Oscar Santos, Dennys Reis, Arnaldo Oliveira-Filho, Cristiano L. Oliveira

Proceedings Volume PC12207, PC122070E (2022) https://doi.org/10.1117/12.2632245

KEYWORDS: Molecules, X-rays, Shape analysis, Scattering, Potassium, Optical microscopy, Laser scattering, Laser optics, Doping

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Proceedings Article | 8 September 2021 Presentation + Paper

X-ray microscopy developments at Sirius-LNLS: first commissioning experiments at the Carnauba beamline

Hélio C. Tolentino, Renan Geraldes, Gabriel B. Z. Moreno, Artur Pinto, Cassiano S. N. Bueno, Leonardo Kofukuda, Anna P. Sotero, Antonio C. Neto, Francesco Lena, Willian Wilendorf, Giovanni Baraldi, Sergio A. Luiz, Carlos S. Dias, Carlos Pérez, Itamar Neckel, Douglas Galante, Veronica Teixeira, Dean Hesterberg

Proceedings Volume 11839, 1183904 (2021) https://doi.org/10.1117/12.2596496

KEYWORDS: Mirrors, Cryogenics, Crystals, Nanoprobes, Imaging spectroscopy, X-rays, Luminescence, X-ray imaging, X-ray fluorescence spectroscopy

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Proceedings Article | 5 March 2021 Presentation

Effect of the anionic azo dye sunset yellow in lyotropic mixtures with uniaxial and biaxial nematic phases

Antônio Figueiredo Neto, Erol Akpinar, Gokhan Topcu, Dennys Reis

Proceedings Volume 11707, 117070H (2021) https://doi.org/10.1117/12.2582566

KEYWORDS: Ions, X-rays, Scattering, Laser scattering, X-ray microscopy, Temperature metrology, Optical microscopy, Molecules, Molecular aggregates, Laser optics

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Proceedings Article | 13 March 2019 Presentation

Influence of an external magnetic field in the two-photon absorption coefficient of magnetite nanoparticles in colloids and thin films (Conference Presentation)

Antonio Figueiredo Neto, Daniel Espinosa, Dennys Reis, Cristiano L. de Oliveira

Proceedings Volume 10941, 1094103 (2019) https://doi.org/10.1117/12.2502912

KEYWORDS: Magnetism, Nanoparticles, Thin films, Absorption, Liquids, Picosecond phenomena, Femtosecond phenomena, Refractive index, X-rays, Light scattering

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Magnetic fluids or ferrofuids (FF) are colloidal suspension of magnetic nanoparticles in a liquid carrier. When a material is illuminated with a high-intensity light, typically nanosecond, picosecond and femtosecond pulsed laser beam, its refractive index n2 and absorption coefficient β depend on the light intensity I. The Z-Scan (ZS) nonlinear optical and the Small-Angle X-Ray Scattering (SAXS) techniques are used to investigate the structure and nonlinear optical properties of magnetite nanoparticles dispersed in a colloid and trapped in thin films. n2 and β were measured as a function of the intensity of an external applied magnetic field H. Different relative orientations of the field with respect to the light-polarization direction were investigated. When the external magnetic field is applied to the colloidal sample (H parallel to the light-polarization direction), β increases with the field, ranging from 1.5 cm/GW (without field) to 2.4 cm/GW (2700 Oe). For the field direction perpendicular to the light polarization direction, β decreases to 1.0 cm/GW (2700 Oe) and after remains stable. These values allowed us to evaluate some elements of the third-order nonlinear optical susceptibility tensor χ^((3)). The SAXS experiments revealed that when the eld is applied, small linear aggregates are formed in the direction of H. Considering that the nanoparticles rotate to align their magnetic moment parallel to the applied field direction, and the particle's magnetic moment is aligned along the ⟨111⟩ lattice direction of the nanoparticle’s crystalline structure, our results indicate an optical anisotropy in magnetite. The calculated third-order nonlinear optical susceptibility, along the ⟨111⟩ direction, is Imχ_xxxx^((3))=2.0(3)×〖10〗^(-20) m^2/V^2, while its average along the other two orthogonal directions is 1/2 (Imχ_yyyy^((3))+Imχ_zzzz^((3)) )=0.9(3)×〖10〗^(-20) m^2/V^2. For the thin-film sample, however, the n2 and β values do not change when the field of 1600 Oe is applied. Within the experimental error, n_2 does not seem to change with field for the colloidal samples. CNPq, FAPESP, CAPES, INCT-FCx and NAP-FCx.

Proceedings Article | 1 March 2019 Presentation + Paper

Hyper-Rayleigh scattering measurements of magnetite nanoparticles: determination of the first order hyperpolarizability anisotropy

E. Gonçalves, R. Fonseca, L. De Boni, A. Figueiredo Neto

Proceedings Volume 10941, 109410G (2019) https://doi.org/10.1117/12.2510249

KEYWORDS: Magnetism, Nanoparticles, Polarization, Scattering, Anisotropy, Q switching, Nonlinear optics, Hyper Rayleigh scattering

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Proceedings Article | 21 April 2017 Presentation

Determination of the two-photon absorption cross-section of magnetite and manganese ferrite nanoparticles in ferrofluids and thin films (Conference Presentation)

Daniel Espinosa, Eduardo Gonçalves, Antonio Figueiredo Neto

Proceedings Volume 10125, 101250L (2017) https://doi.org/10.1117/12.2250636

KEYWORDS: Nanoparticles, Nanotechnology, Absorption, Manganese, Thin films, Nonlinear optics, Liquids, Particles, Refractive index, Camera shutters

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Proceedings Article | 4 March 2014 Paper

New blood markers for staging and prognostics of atherosclerosis

Leticia Sicchieri, Mônica Nascimento Silva, Andrea Moreira Monteiro, Antonio Martins Figueiredo Neto, Lilia Courrol

Proceedings Volume 8947, 89472C (2014) https://doi.org/10.1117/12.2040240

KEYWORDS: Plasmas, Absorption, Biological research, Biosensors, Blood, Europium, Luminescence, Statistical analysis, Glucose, Spectroscopy

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Proceedings Article | 4 March 2014 Paper

Atherosclerosis staging: imaging using FLIM technique

Leticia Sicchieri, Marina Berardi Barioni, Mônica Nascimento Silva, Andrea Moreira Monteiro, Antonio Martins Figueiredo Neto, Amando Ito, Lilia Courrol

Proceedings Volume 8947, 89472B (2014) https://doi.org/10.1117/12.2040139

KEYWORDS: Fluorescence lifetime imaging, Luminescence, Europium, Tissues, Biological research, Microscopy, Statistical analysis, Collagen, Surface plasmons, Inflammation

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Proceedings Article | 5 March 2013 Paper

Investigation of the interaction of alkali ions with surfactant head groups for the formation of lyotropic biaxial nematic phase via optical birefringence measurements

Erol Akpinar, Dennys Reis, Antonio Martins Figueiredo Neto

Proceedings Volume 8642, 864203 (2013) https://doi.org/10.1117/12.981979

KEYWORDS: Neodymium, Ions, Head, Birefringence, Potassium, Sodium, Molecules, Liquid crystals, Temperature metrology, Crystals

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SPIE Journal Paper | 8 November 2012 Open Access

Measurement of the nonlinear optical response of low-density lipoprotein solutions from patients with periodontitis before and after periodontal treatment: evaluation of cardiovascular risk markers

Andrea Monteiro, Maria A. Jardini, Viviana Giampaoli, Sarah Alves, Antonio Figueiredo Neto, Magnus Gidlund

JBO, Vol. 17, Issue 11, 115004, (November 2012) https://doi.org/10.1117/12.10.1117/1.JBO.17.11.115004

KEYWORDS: Plasma, Surface plasmons, Blood, Particles, Teeth, Inflammation, Statistical analysis, Biomedical optics, Magnesium, Pathogens

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SPIE Journal Paper | 1 October 2012 Open Access

Behavior of the thermal diffusivity of native and oxidized human low-density lipoprotein solutions studied by the Z-scan technique

Priscila Santos, Thiago Genaro-Mattos, Andrea Monteiro, Sayuri Miyamoto, Antonio Figueiredo Neto

JBO, Vol. 17, Issue 10, 105003, (October 2012) https://doi.org/10.1117/12.10.1117/1.JBO.17.10.105003

KEYWORDS: Transmittance, Absorption, Particles, Copper, In vitro testing, Spectrophotometry, Statistical modeling, Absorbance, Sensors, Oxidation

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Proceedings Article | 2 August 1995 Paper

Ferronematics and ferrocholesteric lyotropic liquid crystals

Antonio Figueiredo Neto

Proceedings Volume 2372, (1995) https://doi.org/10.1117/12.215541

KEYWORDS: Liquid crystals, Magnetism, Doping, Curium, Information operations, Potassium, Surface plasmons, Inductive coupling, Physics, Anisotropy

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Showing 5 of 12 publications

SPIE Conference Volume | 5 March 2014

Emerging Liquid Crystal Technologies IX

Conference Committee Involvement (15)

Emerging Liquid Crystal Technologies XX

25 January 2025 | San Francisco, United States

Emerging Liquid Crystal Technologies XIX

30 January 2024 | San Francisco, California, United States

Emerging Liquid Crystal Technologies XVIII

1 February 2023 | San Francisco, California, United States

Emerging Liquid Crystal Technologies XVII

25 January 2022 | San Francisco, California, United States

Emerging Liquid Crystal Technologies XVI

6 March 2021 | Online Only, California, United States

Showing 5 of 15 Conference Committees

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