Marcelo Nalin - Academia.edu (original) (raw)

Papers by Marcelo Nalin

$Research paper thumbnail of Nonlinear Refractive Index of Terbium Doped Germanate Glass$

Latin America Optics and Photonics (LAOP) Conference 2022, 2022

2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference (CLEO EUROPE/EQEC), 2011

Page 1. Experimental evidence of asymmetrical spectrum broadening in a heavy-metal oxide glass do... more Page 1. Experimental evidence of asymmetrical spectrum broadening in a heavy-metal oxide glass doped with silver nanoparticles N. Zhavoronkov1, R. Driben2,3, BA Bregadiolli4, M. Nalin4 and BA Malomed3 1Max-Born-Institut ...

Physica B: Condensed Matter, 2015

The influence of both thermal treatment and laser irradiation on the structural and optical prope... more The influence of both thermal treatment and laser irradiation on the structural and optical properties of films in the Sb 2 O 3-Sb 2 S 3 system was investigated. The films were prepared by RF-sputtering using glass compositions as raw materials. Irreversible photodarkening effect was observed after exposure the films to a 458 nm solid state laser. It is shown, for the first time, the use of holographic technique to measure "in situ", simultaneously and independently, the phase and amplitude modulations in glassy films. The films were also photo-crystallized and analysed "in situ" using a laser coupled to a micro-Raman equipment. Results showed that Sb 2 S 3 crystalline phase was obtained after irradiation. The effect of thermal annealing on the structure of the films was carried out. Different from the result obtained by irradiation, thermal annealing induces the crystallization of the Sb 2 O 3 phase. Photo and thermal induced effects on films were studied using UV-Vis and Raman spectroscopy, atomic force microscopy (AFM), thermal analysis (DSC), X-ray diffraction, scanning electron microscopy (MEV) and energy-dispersive X-ray spectroscopy (EDX).

Journal of Chemical Physics, Oct 28, 2006

Analytical Chemistry, Oct 16, 2020

Emerging contaminants, including pharmaceutical compounds, are receiving research attention as a ... more Emerging contaminants, including pharmaceutical compounds, are receiving research attention as a result of their widespread presence in effluents and wastewater treatment plants (WWTPs). The antibiotic ciprofloxacin (CIP) is extensively employed to treat infections in animal and human medicine. Both CIP and its metabolites are common contaminants found in WWTPs. In this study, a label-free ultrasensitive U-bent optical fiber-based immunosensor for the determination of CIP in wastewater samples was developed using the properties of the conducting polymer polyaniline (PANI). The anti-CIP immunoglobulin G (IgG) was deposited on a silica optical fiber surface previously functionalized with PANI. Scanning electron microscopy and micro-Raman spectroscopy were used to investigate the surface of the immunosensor. The analysis of CIP in wastewater was performed without the use of an organic solvent or sample preparation steps, with only the sample dilution in saline buffer (pH = 7.4). The linear range for CIP was from 0.01 to 10,000 ng L −1. The detection limit was 3.30 × 10 −3 ng L −1 and the quantification limit was 0.01 ng L −1. The immunosensor provided a high average recovery of 91% after spiking wastewater samples with CIP at a concentration of 9,100 ng L −1. The method was applied in triplicate to wastewater samples from Quebec (Canada), obtaining concentrations of 549 and 267 ng L −1. A comparison with a reference method showed no significant difference (t-test at 95% confidence). The new technique developed is selective, allowing a quantitative analysis of CIP in wastewater.

Materials Chemistry and Physics, May 1, 2021

ABSTRACT This paper reports on the synthesis and characterization of gel-like calcium polyphospha... more ABSTRACT This paper reports on the synthesis and characterization of gel-like calcium polyphosphate coacervates (Ca-PPCs) with three different [P]:[Ca] ratios as new matrixes for drug release. Caffeine and chlorhexidine were used as model drugs, showing encapsulation efficiency of up to 95.4% and 70.4%, respectively. Based on the correlation coefficient (r2) values, different in vitro release behaviors were determined. While the caffeine release followed the Weibull model, the chlorhexidine release was best described by the Korsmeyer-Peppas model. The caffeine-loaded coacervate sample with the highest Ca2+ concentration (CAFPCa0.5) showed the highest incorporation and a total drug release within 720 min. The Ca-PPC-drug interactions were evaluated by infrared and Raman spectroscopies. The Ca2+ concentration, drug molecule size and intermolecular drug/matrix interactions determined the incorporation and release of drugs in the polyphosphate coacervates. High calcium concentration led to a Ca-PPC with small and tight “cage-like” structure that better incorporated caffeine molecules because of their 4.3 times smaller size compared to chlorhexidine. In addition, caffeine interacted through Van der Walls' forces with polyphosphate and its release from the coacervates was most likely to occur in relation to chlorhexidine, which interacted with the coacervates through hydrogen bonding. Thus, the calcium polyphosphate coacervates loaded with the proposed drugs can be competitive and promising as drug delivery systems.

Solar Energy Materials and Solar Cells

Journal of Non-Crystalline Solids, 2021

Abstract Glass forming regions in the system GaO3/2 – GeO2 – LaO3/2 – BaO have been explored usin... more Abstract Glass forming regions in the system GaO3/2 – GeO2 – LaO3/2 – BaO have been explored using aerodynamic levitation coupled to laser heating synthesis technique. Structure property relationships have been established between the thermal and optical properties of the resulting glass thanks to Raman and Infrared vibrational spectroscopies. The germano-gallate glass networks are mainly made of three-dimensional interconnected corner shared GeO4 and GaO4 tetrahedra forming Ge – O – Ge and Ga – O− – Ge bridges in which gallium tetrahedral GaO4 units are charged-compensated by barium and lanthanum cations. In GeO2-rich compositions, the excess of positive charges produces mainly non-bridging oxygens on germanate moieties, leading to a depolymerization of the glass network. In the case of gallium rich compositions, the infrared cut-off is red-shifted as compared to the germanate glasses, in accordance with the disappearance of germanium associated entities such as germanium and gallium bridges or germanium sites with non-bridging oxygen both vibrating at higher wavenumber.

Physics and Chemistry of Glasses-european Journal of Glass Science and Technology Part B, 2006

Univ Estadual Campinas, Inst Fis Gleb Wataghin, Lab Opt, DFMC, BR-13083970 Campinas, SP, Brazil

Journal of Materials Research and Technology, 2021

Abstract New magnetic glass compositions, based on system (100-x) (60GeO2 -25B2O3 –4Al2O3 -10Na2O... more Abstract New magnetic glass compositions, based on system (100-x) (60GeO2 -25B2O3 –4Al2O3 -10Na2O–1PbO) – xTb4O7 were prepared by the melt-quenching technique. The materials were systematically characterized with respect to their structural (XRD, EXAFS, XANES and Raman), thermal (DSC), morphological, optical, magnetic and magneto-optical (MO) properties. Morphological and magnetic measurements show the homogeneous distribution of the Tb3+ ions as the magnetic susceptibility increases proportionally to the rare earth content. The optical window covers the range from 0.5 up to 1.6 μm, limited by absorption due to 4f8 -> 4f7 5 d 1and 4f8 -> 4f8 transitions of Tb3+. XANES and EXAFS measurements at the Ge–K edge show that the germanium atoms are always tetrahedrally coordinated, while results at the Tb-LIII edge shows terbium atoms to be eight-coordinated and exclusively present in the oxidation state 3+ independently of the glass composition. MO measurements show that the Verdet constant (VB) increases linearly with the Tb3+ concentration reaching the value of −83.9 rad T−1m−1 at 650 nm for glass containing 8 mol% of Tb4O7. Good thermal stability (ΔT = 200 °C) allowed obtaining an optical fiber of a glass containing 4 mol% of Tb4O7 featuring VB values of −37.9, −23.6 and −5.89 rad T−1 m−1, at 500, 650 and 1550 nm, respectively.

Materials Research Bulletin, 2021

Abstract Ho3+-doped YNbO4 and Y3NbO7 phosphors were synthesised via a co-precipitation synthesis ... more Abstract Ho3+-doped YNbO4 and Y3NbO7 phosphors were synthesised via a co-precipitation synthesis route. Structural characterisation and spectroscopic properties were performed as a function of the Ho3+ concentration. The Rietveld type-refinement confirms the stabilisation of the pure monoclinic Fergusonite YNbO4 phase at the highest temperatures, but the quadratic phase is stabilised for the lowest temperature, whereas a pure cubic fluorite Y3NbO7 phase was observed for all of the heat treatments. Raman and infrared spectroscopies were used to compare the cation-oxygen vibrational modes. Emission spectra and up-conversion processes were obtained under excitation at 445 and 975 nm respectively. For a similar Ho3+ content, the energy transfers observed show differences between the two crystalline compounds that are related to a stronger interaction between the holmium cations in the fluorite host lattice.

Ceramics International, 2020

A series of new transparent and magnetic germanoborate glasses in the system (100-x)[60GeO2-25B2O... more A series of new transparent and magnetic germanoborate glasses in the system (100-x)[60GeO2-25B2O3-10Na2O-4Al2O3-1PbO]-(x) Gd2O3, with x = 0, 1, 2, 5, 10, 15 and 20 mol%, was prepared and studied with respect to their thermal and structural changes in the presence of Gd2O3. Based on Differential Scanning Calorimetre (DSC) analysis, a glass with 5% of Gd2O3 showed a high thermal stability, which progressively decreases for samples with higher content of Gd2O3. By the analysis of Raman and Fourier Transform Infrared (FTIR) spectra, it was possible to identify that by increasing the amount of Gd2O3, a progressive depolymerization of 6-membered Ge [IV] rings is promoted, concomitant with an increase of Ge [IV] tetrahedra units with non-briding oxygens. The structural analysis through the local-sensitive techniques EXAFS (Extended X-ray Absorption Fine Structure) and XANES (X-ray Absorption Near Edge Structure) showed that the short-range structural modification around the elements Ge and Gd 3+ does not change with the addition of Gd2O3 and the presence of germanium four-fold coordination [Ge IV ] and Gd 3+ states, respectively. A simulation of the coordination number (N), the interatomic distance (R) of Ge-O and Gd-O bonds and the Debye-Waller factor was also carried out. The microstructure, after crystallization, of the sample with 15 mol% of Gd2O3 was evaluated using optical and electron microscopes. Finally, the paramagnetic behaviour and ion probe quantification of Gd 3+ ions were obtained based on magnetic susceptibility measurements.

Journal of Alloys and Compounds, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.