Navegando por Orientadores "CHAVES NETO, Antonio Maia de Jesus"

Agora exibindo 1 - 12 de 12

Acesso aberto (Open Access)
Espectrometria Raman, UV, DOS e Circular Dicroísmo de alcalóides do cigarro
(Universidade Federal do Pará, 2011-02-28) GUEDES, Alberto Monteiro; CHAVES NETO, Antonio Maia de Jesus; http://lattes.cnpq.br/3507474637884699
This work is about spectroscopic analysis of some molecular structures present in tobacco (Nicotiana glauca), the base for cigarette, and their interactions with the DNA molecule. According to its importance, among the variety present in the cigarette, the molecules studied were derived from nicotinic acid, nicotinic acid (niacin / vitamin B3), nicotinamide, trigonelline, nicotine, nornicotine and anabasine. The optimizations of these structures were initially obtained in the Hyperchem 7.5 computational software based on the theory of molecular mechanics. Then, they were optimized using the method Density Functional Theory, on the basis B3LYP/ 6-311 + + G (d, p), simulated in software Gaussian 03. Once the optimized structures, we obtained the UV absorption, Raman, Infrared, Circular Dichroism and Density of States spectra using Time-Dependent Density Functional Theory also simulated the in the same software. At the end of this process was also simulated, via molecular mechanics, the interactions of these structures with the DNA molecule in order to verify the potential carcinogenic or not these substances.
Acesso aberto (Open Access)
Estudo das ftalocianinas metálicas na adsorção de gases do efeito estufa e poluentes utilizando docagem molecular
(Universidade Federal do Pará, 2025-04-30) SOUSA, José Antonio Ferreira de; OLIVEIRA, Mozaniel Santana de; http://lattes.cnpq.br/0810227136654245; CHAVES NETO, Antonio Maia de Jesus; http://lattes.cnpq.br/3507474637884699
Atmospheric pollution, driven by the emission of toxic gases, represents an environmental and public health challenge. This study investigates the application of phthalocyanines (Pc) and metal phthalocyanines (MPc) of iron (FePc), cobalt (CoPc), copper (CuPc), zinc (ZnPc), and titanium (TiPc) for the capture of gases such as carbon dioxide (CO₂), carbon monoxide (CO), ammonia (NH₃), hydrogen cyanide (HCN), hydrogen sulfide (H₂S), and aromatic compounds like benzene (C₆H₆). AutoDock Vina 1.2.0 and Gaussian 09W were the software employed in the molecular docking technique to investigate these interactions. Gaussian 09W enabled adjustments in atomic positions to minimize the total interaction energy and build the molecular models. AutoDock Vina 1.2.0 facilitated the calculation of the most favorable binding mode between the toxic molecules and the MPc and Pc, providing detailed information on the most stable adsorption positions, orientations, and energies. The analyses indicate that MPc and Pc exhibit the best interactions with C₆H₆, while the weakest coupling occurred with H₂S. Among the evaluated substances, the best binding interactions occurred with MPc, and among them, TiPc proved to be the most efficient, exhibiting the strongest attraction to CO₂. These molecules are highly promising for the capture and elimination of the tested molecules and, consequently, constitute fundamental strategies for protecting the environment, promoting public health, and ensuring sustainable development for future generations.
Acesso aberto (Open Access)
Estudo de nanofios de Au e dendrímeros
(Universidade Federal do Pará, 2010-01-12) COSTA, José Francisco da Silva; CHAVES NETO, Antonio Maia de Jesus; http://lattes.cnpq.br/3507474637884699
First part of this work is about the classical molecular dynamics simulation of the interaction of matrix systems of parallel nanowires of Au as a function of time. The results find the time of collision between the wires of the array. The second part of this work is using classical molecular dynamics simulation for five generations of PAMAM dendrimers, each interacting individually with a carbon nanotube as a function of time resulting in a molecular motor. Furthermore, it were calculated the absorption spectra of this system and it was found that they could be nanomotors controlled by light. For all these systems were calculated kinetic energy, potential, speed, thermodynamic properties as molar entropy variation, molar heat capacity and temperature in situ. These quantities provide us with valuable information about the behavior of these systems.
Acesso aberto (Open Access)
Interações com nanotubos de carbono e pontos quânticos de óxido de grafeno com estruturas externas do Sars-cov-2 via simulações de dinâmica e docagem molecular
(Universidade Federal do Pará, 2023-06-02) LOBATO, Júlio César Mendes; OLIVEIRA, Mozaniel Santana de; http://lattes.cnpq.br/0810227136654245; https://orcid.org/0000-0002-4076-2443; CHAVES NETO, Antonio Maia de Jesus; Lattes: 3507474637884699
The interaction between nanoparticles and SARS-CoV-2 virus proteins was evaluated using ligands such as single-walled carbon nanotubes (NTCPUs) and receptors including envelope protein (E-pro), major protease (M-pro) and Spike glycoprotein (Sgly). Molecular docking modeling and molecular dynamics techniques were applied. Molecular dynamics revealed root mean square shift of atomic positions ranging from 0.5Å to 3.0Å. The results indicated that the zigzag nanotube showed better affinity energy, with binding free energy values of -9.48, -9.98 and -10.08 kcal/mol for E-pro, M-pro and S-gly, respectively. Furthermore, the mean square deviation of the atomic positions remained more stable for this type of nanotube, indicating a high probability of binding to the active sites of the macromolecules. Molecular couplings and binding free energy showed strong interaction between NTCPUs and residues of the S-gly active site, with values of -112.73, -94.38 and -80.49 kcal/mol for zigzag, chiral and armchair ligands, respectively. In a second step, five graphene oxide (GO) quantum dots smaller than 20 nm were used as ligands, interacting only with the spike receptors of three different strains: S-GLY-OMICRON, S-GLY-KAPPA and S-GLY-DELTA. Comparing the two ligands, it was observed that the S-GLY-OMICRON/OG-E interaction showed better affinity with Gibbs free energy of 172.2510 KJ/mol, compared to the better affinity of carbon nanotubes, S-gly/zig-zag, with ΔG of -112.73 KJ/mol. The eight proposed ligands have a high probability of binding to the active sites of the macrostructures. In conclusion, both carbon nanotubes and OG showed promise for application in SARS-CoV-2 inhibitor products, such as the development of materials for the manufacture of personal protective equipment, sprays and waterproofing solutions in general.
Acesso aberto (Open Access)
Interações de carvão ativado, fármacos e libidibia ferrea contra o vírus SARS-COV-2
(Universidade Federal do Pará, 2021-08-25) ARAÚJO, Herica Daniele Costa; CHAVES NETO, Antonio Maia de Jesus; http://lattes.cnpq.br/3507474637884699; https://orcid.org/0000-0002-9730-3512
The high rates of infection and mortality from Severe Acute Respiratory Syndrome (SARS-CoV-2) or COVID-19 infection has caused severe socio-economic impacts worldwide. Transmission basically occurs through contact with bodily fluids. In the airways, by spraying droplets and/or aerosols suspended in the environment and/or deposited on surfaces. The effectiveness of using effective masks to contain contagion is a necessity. The present work evaluated the adsorption capacity of filters containing activated carbon and modified activated carbon during nanofiltration in masks with greater efficiency. The possible interactions between Spike (S) and membrane (M) proteins with activated carbon oxygen non-modified and activated carbon oxygen modified were evaluated by docking and molecular dynamics. Autodock Vina 4.2.6 and AMBER 16 software were used in the simulations. Results of the formed ligand-receptor complexes had the affinity energy, the root mean-square deviation (RMSD) and the Gibbs free energy of binding evaluated. Activated carbon oxygen modified showed greater spontaneity in protein interactions. And, another front to combat the coronavirus was addressed in this work: the treatment of the infected, as evaluations of the inhibitory action of the active principles of retroviral drugs known in the literature, as well as new compounds from the Brazilian Amazon flora were docked with proteins S, M and envelope (E). Three drugs (Colchicine, Nafamostat and Selinexor) and three compounds originated from Libidibia ferrea or Caesalpinia ferrea (Elagic Acid, Pauferrol A and Sitosterol) interacted as ligands. And, after docking, the most favorable affinity energies of the active sites established between ligands and receptors were graphically demonstrated. The docking was carried out through the SwissDock server. The interactions of the ligands Pauferrol A and Colchicine on the proteins contained in the viral surface were highlighted.
Acesso aberto (Open Access)
Interações de ftalocianinas de Co, Cu e não metálicas com estruturas externas de SARS-CoV-2 utilizando docking e dinâmica molecular
(Universidade Federal do Pará, 2021-12-22) ALENCAR, Wilson Luna Machado; CHAVES NETO, Antonio Maia de Jesus; http://lattes.cnpq.br/3507474637884699; https://orcid.org/0000-0002-9730-3512
Acesso aberto (Open Access)
Nanofiltração de hormônios e metais pesados em nanotubos de carbono e de boro por dinâmica molecular
(Universidade Federal do Pará, 2020-02-27) CAVALEIRO, Rosely Maria dos Santos; CHAVES NETO, Antonio Maia de Jesus; http://lattes.cnpq.br/3507474637884699; https://orcid.org/0000-0002-9730-3512
Sewage treatment stations receive various effluents and perform the selective filtering of molecules that can, if they persist in the water, contaminate or the environment. Selection processes initiated by larger sections down to nanoparticles. Among the molecules called emerging contaminants are hormones and heavy metals that impact on graves consequences on organisms by endocrine-disrupting action. When surface waters receive effluents with traces of contamination and hormones or heavy metals, they will cause diseases in living beings, especially in pregnant women and children, as well as interfering in the chains of DNA, also affecting the next generations. This study of molecular tests carried out with nanofiltration: water with hormones and water with heavy metals filtered through carbon nanotubes and boron nitrogen, under the action of 8 (eight) electric fields lasting 100 (hundred) ps. The study hormones were: estrone, estradiol, estriol, progesterone, ethinylestradiol, levonorgestrel, diethylbestrol, and heavy metal ions: lead, cadmium, iron, zinc, and mercury. Each of the hormone molecules and the heavy metal were filtered through two nanotubes, under the same boundary conditions. The selected results that allow creating nanofiltration systems that can be removed micropollutants using carbon nanotubes or boron nitride activated by the uniform electrical fields from 10-5 a.u. to 10-8 a.u.
Acesso aberto (Open Access)
. Predição das propriedades termodinâmicas do biodiesel e diesel comum, suas blendas e efeitos de aditivos via teoria do funcional da densidade e ensemble canônico.
(Universidade Federal do Pará, 2019-11-08) ROCHA, Adriano Santos da; CHAVES NETO, Antonio Maia de Jesus; http://lattes.cnpq.br/3507474637884699
In this study, we analyzed the thermodynamic properties of soy biodiesel, the most widely used biodiesel source among the world's largest consumers, and rapeseed biodiesel, a source with significant employment in the European Union and biodiesel additives. Also, the study of ordinary diesel was carried out to simulate the situations in which this fuel is in mixtures with different concentrations of biodiesel blends. The objective of this work is to study the thermodynamic properties of the fuels mentioned. Based, where possible, on experimental results to validate the expansion of theoretical results and point out the most appropriate methodology for this type of approach. To this end, computational simulations were carried out with theoretical support in the Density Functional Theory combined with the canonical ensemble model. The functional used in the simulations was type B3LYP with bases 6-31 + (d) and 6-311 + g (d), in addition to the composite method CBS-QB3. The calculated enthalpy values are higher in the biofuels in relation to diesel and the same happened with Entropy. When we analyze the change of Gibbs Free Energy, the largest variations were noted for biofuels. The coefficient of adiabatic expansion revealed lower degrees of freedom until 400 K temperature in both types of biodiesel, from that point all fuels have the same behavior for this property. The lowest relative error was found with the B3LYP/6-311 +g(d) method, with a value of 0.15% for the combustion of ordinary diesel. In relation to biofuels, the same method provided 0.48% relative error in the combustion of rapeseed biodiesel as the best result. Regarding the effects of temperature on these fuels, the results showed that both types of biodiesel are less susceptible to heating than ordinary diesel at all calculated points, always requiring more energy to raise their temperature. The results in the additives showed that the antioxidant pyrogallol that most interferes in the biodiesel properties.
Acesso aberto (Open Access)
Propriedades Térmicas do (Bio)Butanol e a Fotocatálise do Grafeno com Trifenilamina Dopado com Metais para Geração de H2
(Universidade Federal do Pará, 2019-01-10) MARTINS, Marcelo Gonçalves; CHAVES NETO, Antonio Maia de Jesus; http://lattes.cnpq.br/3507474637884699
In this study, the optical properties and electronic structures of the transition metal-doped G-TPA using water as solvent were theoretically investigated in order to evaluate the efficiency in the production of photocatalytic hydrogen. in the Gaussian 09W software, using the B3LYP functional for all structures, and the base 6-31g (d) for the H, C and N atoms, and the LANL2DZ base, applying the effective potentials method for the transition metals (Ni, Pt, Pd, Fe, Os). Through the DOS of each structure an increase of accessible states in the valence layer was observed, as well as the decrease of the gap for all doping and for the structure with two and three radicals of triphenylamine. Through the UV-vis absorption spectrum, there was an improvement in absorption in the range of 490 nm to 615 nm. Another analysis carried out in the sense of energy generation was the evaluation of the thermodynamic potential of the butanol properties as complementary fuel or substitute for conventional fuels. For this, the Gaussian09W allied to the DFT was used again, but combined with the functional ones, hybrid B3LYP with the base set 6-311 ++ G (d, p) and 6-31 + G (d), G3 and G4 , in addition to the CBS / QB3 compounds. The simulations were carried out and the thermodynamic properties were found, such as: the specific molar heat at constant pressure, the enthalpy of formation and the entropy. All the properties were obtained between the temperatures 100K - 1500K and constant pressure of 1atm, in addition the enthalpies of combustion of the butanol isomers were obtained, several ternary mixtures were also proposed where it was possible to compare the enthalpy variations between the fuels: gasoline, ethanol and n-butanol.
Acesso aberto (Open Access)
Propriedades termodinâmicas: querosene, bioquerosene, aditivos e mecanismos de detecção de explosivos
(Universidade Federal do Pará, 2018-11-23) MORAES, Edimilson dos Santos; CHAVES NETO, Antonio Maia de Jesus; http://lattes.cnpq.br/3507474637884699
In this work we perform the characterization of thermodynamic potentials, obtaining predictions based on Density Functional Theory and statistical thermodynamics, through the canonical ensemble model. The study compared two theoretical methods, B3lyp/6-311 ++ g(d, p) and the semi-empirical method PM3, with the experimental values of the thermodynamic property of CP with the objective of validating the method with better precission. All simulations were performed conformation of the global minimums and optimizations of the molecules in thermal equilibrium and for a temperature range of 0.5 - 1500 K. We will analyze the thermal properties, such as energy, enthalpy, Gibbs free energy, entropy, heat capacity at constant pressure with respect to temperature. In the combustion enthalpy the following methods were used: B3lyp/6-311 ++ g(d, p), B3lyp/6- 31+g(d), CBS-QB3, G3, G4 and the G3 / G4 mean, obtaining results that show a good agreement with the experimental values, and verifying which of the methods best predicts the thermodynamic properties for reactions of combustion of the kerosene and bioquerosene. Also, a theoretical analysis was performed in DFT to calculate the thermodynamic properties of three molecules of additives. We simulated a composition of JP-8 with mixtures of the three additives together and separated in order to observe its efficiency over other existing methods. Then, the thermodynamic properties of the gasoline with additives were predicted under the same conditions already described. These calculated amounts included standard gasoline mixed with the following oxygenated additives: methyl tert-butyl ether, ethyl tert-butyl ether, diisopropyl ether, ethanol and methanol. It is possible to estimate some relevant fuel properties in the injection and combustion stage, showing substantial agreement with the experimental data, presenting relative errors of less than 2%, thus establishing an excellent method to calculate and predict the thermodynamic properties of the combustion reactions for with additives. In the last stage of this work, we present a theory of a simulated sensor device to identify explosive molecules that is of extreme interest for the area of public security in the fight against terrorism. For this, an armchair-type carbon nanotube (CNT) was modeled under the action of an external, longitudinal and uniform electric field, causing the molecules of the explosives: 2,4,6 trinitrotoluenes, triacetin triperoxide, hexogen, hexamethylene triperoxide diamine, octogen and pentaerythritol tetranitrate. Turn around the CNT, behaving as a sensor depending on the temperature and the radius of rotation of the molecules. In this way, we study the physico-chemical properties of the interactions of the molecules with the CNT.
Acesso aberto (Open Access)
Sensores de narcóticos, gás natural e syngás utilizando nanotubos de carbono sob ação de campo elétrico externo
(Universidade Federal do Pará, 2021-02-15) AIRES, Júlio Cesar Nunes; CHAVES NETO, Antonio Maia de Jesus; http://lattes.cnpq.br/3507474637884699; https://orcid.org/0000-0002-9730-3512
This work presents an analysis of the molecular dynamics between several illicit drugs: benzoylmethylecgonine, diacetylmorphine, 3,4 methylenedioxymethamphetamine, D-Deoxefedrine, lysergic acid diethylamide and, interacting with a section of carbon nanotubes at low initial temperature, corresponding to 10-3 K, and under a uniform electric field, like a drug detection system. In addition to the analysis of the behavior of natural gas molecules and SYNGAS interacting with a carbon nanotube at an initial simulation temperature of 300K, with all systems being relaxed by 50 ps outside the carbon nanotube, describing each possible arrangement for capture; a constant external electric field was then applied to the systems, longitudinally, along the length of the carbon nanotube, promoting an evanescent effect, capable of trapping them orbiting the carbon nanotube. Simulations for electric field intensities within a range of 10-5 to 10-1 a.u. were performed, to verify the behavior of drugs, while for the molecules that comprise Natural Gas and SYNGAS, a range of 10-8 to 10-1 a.u. was adopted. Average orbital radii were estimated, in addition to a number of thermodynamic properties. Our results indicate that the combination of a uniform external electric field and van der Waals interactions in a carbon-derived nanotube is enough to create an evanescent field of attractive potential, modeling it as a system for the detection of temperature and drug rays .
Acesso aberto (Open Access)
Teoria do funcional de densidade e ensemble canônico para análise termodinâmica do gás natural, gás de síntese e de suas misturas
(Universidade Federal do Pará, 2018-10-05) GOMES NETO, Abel Ferreira; CHAVES NETO, Antonio Maia de Jesus; http://lattes.cnpq.br/3507474637884699
In this work we performed a thermodynamic characterization of natural gas, synthesis gas and the mixtures of these two fuels, obtaining predictions based on the density functional theory and on statistical thermodynamics, through the canonical ensemble model. The study initially focused on verifies what method of the Density Functional Theory is more suitable for the thermodynamic analysis of natural gas, where properties were obtained, such as the following thermodynamic potentials: internal energy, enthalpy, Gibbs free energy and entropy. We conclude that B3LYP functional, along with the basis sets 6-311++g(d,p) corresponds to the most recommended method for the thermodynamic prediction of this fuel, the thermodynamic properties of the synthesis gas were analyzed, as well as the effects caused by the synthesis gas when mixed with natural gas. The results showed the synthesis gas can be a possible anti-knock additive, which a mixture containing up to 30% of synthesis gas can raise the resistance of natural gas to heating, reducing only about 15% of the energy their released in the combustion.