Nor-β-lapachone-loaded (NβL-loaded) microcapsules were characterized. The NβL-loaded PLGA microca... more Nor-β-lapachone-loaded (NβL-loaded) microcapsules were characterized. The NβL-loaded PLGA microcapsules exhibited a pronounced initial burst release. The cytotoxic activity against a set of cancer cell lines was investigated.
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, Jan 5, 2017
The chemical imidacloprid belongs to the neonicotinoids insecticide class, widely used for insect... more The chemical imidacloprid belongs to the neonicotinoids insecticide class, widely used for insect pest control mainly for crop protection. However, imidacloprid is a non-selective agrochemical to the insects and it is able to kill the most important pollinators, the bees. The high toxicity of imidacloprid requires controlled release and continuous monitoring. For this purpose, high performance liquid chromatography (HPLC) is usually employed; infrared and Raman spectroscopy, however, are simple and viable techniques that can be adapted to portable devices for field application. In this communication, state-of-the-art quantum level simulations were used to predict the infrared and Raman spectra of the most stable conformer of imidacloprid. Four molecular geometries were investigated in vacuum and solvated within the Density Functional Theory (DFT) approach employing the hybrid meta functional M06-2X and the hybrid functional B3LYP. The M062X/PCM model proved to be the best to predict...
The role of hydration on the structural, electronic, optical, and vibrational properties of monoh... more The role of hydration on the structural, electronic, optical, and vibrational properties of monohydrated (CaCO3·H2O, hexagonal, P31, Z = 9) and hexahydrated (CaCO3·6H2O, monoclinic, C2/c, Z = 4) calcite crystals is assessed with the help of published experimental and theoretical data applying density functional theory within the generalized gradient approximation and a dispersion correction scheme. We show that the presence of water increases the main band gap of monohydrocalcite by 0.4 eV relative to the anhydrous structure, although practically not changing the hexahydrocalcite band gap. The gap type, however, is modified from indirect to direct as one switches from the monohydrated to the hexahydrated crystal. A good agreement was obtained between the simulated vibrational infrared and Raman spectra and the experimental data, with an infrared signature of hexahydrocalcite relative to monohydrocalcite being observed at 837 cm(-1). Other important vibrational signatures of the lattice, water molecules, and CO3(2-) were identified as well. Analysis of the phonon dispersion curves shows that, as the hydration level of calcite increases, the longitudinal optical-transverse optical phonon splitting becomes smaller. The thermodynamics properties of hexahydrocalcite as a function of temperature resemble closely those of calcite, while monohydrocalcite exhibits a very distinct behavior.
Science China Physics, Mechanics & Astronomy, 2014
ABSTRACT The structural, electronic, and optical absorption properties of TiO2 nanotube (TiO2NT) ... more ABSTRACT The structural, electronic, and optical absorption properties of TiO2 nanotube (TiO2NT) with Cu n clusters (n =1–4) adsorbed on its surface have been investigated based on density functional theory calculations. The TiO2NT is constructed by rolling up a (101) sheet of anatase TiO2 around the \([\bar 101]\) direction; the ground states of Cun/TiO2NT systems are determined by analyzing the average adsorption energies. Calculation results show that odd-even oscillations occur for the average adsorption energy, the Cu-O bond length, and the amount of transferred electrons, with the increase in Cu n cluster size; and the Cu n /TiO2NTs with odd n’s demonstrate stronger interaction between the Cu n cluster and the TiO2NT. Also, the impurity states introduced by the Cu n cluster to the band gap of TiO2NT cause an obvious redshift of the optical absorption spectrum toward the visible light region, especially for the even n cases.
We present some computational simulations of graphene-based nanoribbons with a number of half-twi... more We present some computational simulations of graphene-based nanoribbons with a number of half-twists varying from 0 to 4 and two types of defects obtained by removing a single carbon atom from two different sites. Optimized geometries are found by using a mix of classical-quantum semiempirical computations. According with the simulations results, the local curvature of the nanoribbons increases at the
We employ quantum biochemistry methods based on the Density Functional Theory (DFT) approach to u... more We employ quantum biochemistry methods based on the Density Functional Theory (DFT) approach to unveil the detailed binding energy features of willardiines co-crystallized with the AMPA receptor. Our computational results demonstrate that the total binding energies of fluorine-willardiine (FW), hydrogen-willardiine (HW), bromine-willardiine (BrW) and iodine-willardiine (IW) to the iGluR2 ligand-pocket correlate with the agonist binding energies, whose experimental sequential data match our computational counterpart, excluding the HW case. We find that the main contributions to the total willardiine-iGluR2 binding energy are due to the amino acid residues in decreasing order Glu705 > Arg485 > Ser654 > Tyr450 > T655. Furthermore, Met708, which is positioned close to the 5-substituent, attracts HW and FW, but repels BrW and IW. Our results contribute significantly to an improved understanding of the willardiine-iGluR2 binding mechanisms.
ABSTRACT The axial sliding of carbon-based normal nanorings (NCNs) and one-turn Möbius nanorings ... more ABSTRACT The axial sliding of carbon-based normal nanorings (NCNs) and one-turn Möbius nanorings (MCNs) along inner coaxial carbon nanotubes with hydrogen-terminated edges is described. Classical molecular dynamics simulations were carried out to investigate their sliding considering C300H100 NCN and MCN nanostructures and single wall armchair carbon nanotubes (SW CNTs) with chiralities (16, 16), (18, 18), and (20, 20). The NCN:CNT system exhibited an oscillatory movement with an initial frequency of about 10 gigahertz decaying slowly with time as the vibrational energy is transferred to radial and torsional modes of the nanoring, while the amplitude remained practically constant except for the (16, 16)-CNT. The MCN:CNT systems, on the other hand, initially oscillated as the NCN:CNT, but a strong damping regime ensued due to the strong interaction of the twisted nanoring with the CNT tips, effectively stopping the oscillation after 400 ps for all MCN:CNT structures investigated.
Nor-β-lapachone-loaded (NβL-loaded) microcapsules were characterized. The NβL-loaded PLGA microca... more Nor-β-lapachone-loaded (NβL-loaded) microcapsules were characterized. The NβL-loaded PLGA microcapsules exhibited a pronounced initial burst release. The cytotoxic activity against a set of cancer cell lines was investigated.
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, Jan 5, 2017
The chemical imidacloprid belongs to the neonicotinoids insecticide class, widely used for insect... more The chemical imidacloprid belongs to the neonicotinoids insecticide class, widely used for insect pest control mainly for crop protection. However, imidacloprid is a non-selective agrochemical to the insects and it is able to kill the most important pollinators, the bees. The high toxicity of imidacloprid requires controlled release and continuous monitoring. For this purpose, high performance liquid chromatography (HPLC) is usually employed; infrared and Raman spectroscopy, however, are simple and viable techniques that can be adapted to portable devices for field application. In this communication, state-of-the-art quantum level simulations were used to predict the infrared and Raman spectra of the most stable conformer of imidacloprid. Four molecular geometries were investigated in vacuum and solvated within the Density Functional Theory (DFT) approach employing the hybrid meta functional M06-2X and the hybrid functional B3LYP. The M062X/PCM model proved to be the best to predict...
The role of hydration on the structural, electronic, optical, and vibrational properties of monoh... more The role of hydration on the structural, electronic, optical, and vibrational properties of monohydrated (CaCO3·H2O, hexagonal, P31, Z = 9) and hexahydrated (CaCO3·6H2O, monoclinic, C2/c, Z = 4) calcite crystals is assessed with the help of published experimental and theoretical data applying density functional theory within the generalized gradient approximation and a dispersion correction scheme. We show that the presence of water increases the main band gap of monohydrocalcite by 0.4 eV relative to the anhydrous structure, although practically not changing the hexahydrocalcite band gap. The gap type, however, is modified from indirect to direct as one switches from the monohydrated to the hexahydrated crystal. A good agreement was obtained between the simulated vibrational infrared and Raman spectra and the experimental data, with an infrared signature of hexahydrocalcite relative to monohydrocalcite being observed at 837 cm(-1). Other important vibrational signatures of the lattice, water molecules, and CO3(2-) were identified as well. Analysis of the phonon dispersion curves shows that, as the hydration level of calcite increases, the longitudinal optical-transverse optical phonon splitting becomes smaller. The thermodynamics properties of hexahydrocalcite as a function of temperature resemble closely those of calcite, while monohydrocalcite exhibits a very distinct behavior.
Science China Physics, Mechanics & Astronomy, 2014
ABSTRACT The structural, electronic, and optical absorption properties of TiO2 nanotube (TiO2NT) ... more ABSTRACT The structural, electronic, and optical absorption properties of TiO2 nanotube (TiO2NT) with Cu n clusters (n =1–4) adsorbed on its surface have been investigated based on density functional theory calculations. The TiO2NT is constructed by rolling up a (101) sheet of anatase TiO2 around the \([\bar 101]\) direction; the ground states of Cun/TiO2NT systems are determined by analyzing the average adsorption energies. Calculation results show that odd-even oscillations occur for the average adsorption energy, the Cu-O bond length, and the amount of transferred electrons, with the increase in Cu n cluster size; and the Cu n /TiO2NTs with odd n’s demonstrate stronger interaction between the Cu n cluster and the TiO2NT. Also, the impurity states introduced by the Cu n cluster to the band gap of TiO2NT cause an obvious redshift of the optical absorption spectrum toward the visible light region, especially for the even n cases.
We present some computational simulations of graphene-based nanoribbons with a number of half-twi... more We present some computational simulations of graphene-based nanoribbons with a number of half-twists varying from 0 to 4 and two types of defects obtained by removing a single carbon atom from two different sites. Optimized geometries are found by using a mix of classical-quantum semiempirical computations. According with the simulations results, the local curvature of the nanoribbons increases at the
We employ quantum biochemistry methods based on the Density Functional Theory (DFT) approach to u... more We employ quantum biochemistry methods based on the Density Functional Theory (DFT) approach to unveil the detailed binding energy features of willardiines co-crystallized with the AMPA receptor. Our computational results demonstrate that the total binding energies of fluorine-willardiine (FW), hydrogen-willardiine (HW), bromine-willardiine (BrW) and iodine-willardiine (IW) to the iGluR2 ligand-pocket correlate with the agonist binding energies, whose experimental sequential data match our computational counterpart, excluding the HW case. We find that the main contributions to the total willardiine-iGluR2 binding energy are due to the amino acid residues in decreasing order Glu705 > Arg485 > Ser654 > Tyr450 > T655. Furthermore, Met708, which is positioned close to the 5-substituent, attracts HW and FW, but repels BrW and IW. Our results contribute significantly to an improved understanding of the willardiine-iGluR2 binding mechanisms.
ABSTRACT The axial sliding of carbon-based normal nanorings (NCNs) and one-turn Möbius nanorings ... more ABSTRACT The axial sliding of carbon-based normal nanorings (NCNs) and one-turn Möbius nanorings (MCNs) along inner coaxial carbon nanotubes with hydrogen-terminated edges is described. Classical molecular dynamics simulations were carried out to investigate their sliding considering C300H100 NCN and MCN nanostructures and single wall armchair carbon nanotubes (SW CNTs) with chiralities (16, 16), (18, 18), and (20, 20). The NCN:CNT system exhibited an oscillatory movement with an initial frequency of about 10 gigahertz decaying slowly with time as the vibrational energy is transferred to radial and torsional modes of the nanoring, while the amplitude remained practically constant except for the (16, 16)-CNT. The MCN:CNT systems, on the other hand, initially oscillated as the NCN:CNT, but a strong damping regime ensued due to the strong interaction of the twisted nanoring with the CNT tips, effectively stopping the oscillation after 400 ps for all MCN:CNT structures investigated.
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Papers by Ewerton Caetano