Fernando Cunha Peixoto

Scopus Publications

Analysis of Sugar Distributions in Barley Wort Saccharification via Capillary Electrophoresis
Rafaella Silva Aredes, Fernando Cunha Peixoto, Leandro Alcoforado Sphaier, Vinicius Nunes Henrique Silva, Lucas Mattos Duarte, and Flávia Ferreira de Carvalho Marques
American Chemical Society (ACS)

Predicting Optical Properties of Pyrotechnic Illuminant Compositions Using Multiple Linear Regression Model
Luciana Amorim da Silva, Erick Braga Ferrão Galante, Fernando Cunha Peixoto, and Aline Cardoso Anastácio
Informa UK Limited

Heat and mass transfer with chemical kinetics in alcoholic fermentation of multiple sugars: Lumped formulation and dimensional analysis
I.F. Pinheiro, H.L. Serrano, L.A. Sphaier, F.C. Peixoto, and V.N.H. Silva
Elsevier BV

Solving boundary value problems in heterogeneous catalysis with orthogonal collocation and arc-length continuation
André Von‐Held Soares, Housam Binous, Fernando Cunha Peixoto, and Ahmed Bellagi
Wiley
AbstractAn important part of the education of chemical engineers involves the design and assessment of heterogeneous catalytic reactions. They pose fundamental phenomena and constitute invaluable industrial processes. Progressing in this field, especially in graduate‐level courses, entails solving nonlinear differential equations systems, which can only be achieved by using efficient and reliable numerical techniques. In this work, we solve nonisothermal one‐dimensional reaction‐diffusion BVP considering convection in the boundary conditions, by applying orthogonal collocation and arc‐length continuation. Particularly, we predict the effectiveness factor as a function of the Thiele modulus for the main three particle geometries: plane slab, cylinder, and sphere. For chemical engineering students, such problems are at the zenith of the discipline, and the results of such calculations can elucidate basic and advanced concepts of mass and heat transfer as well as chemical reaction engineering. Both Chebyshev and shifted Legendre polynomials were used to transform the boundary value problem into a set of algebraic nonlinear equations. In addition, we also compare our findings against the available analytic solutions whenever possible. Codes in Scilab, Matlab®, and Mathematica© were developed for the solution of such problems and are available in the Supporting Information. There are two possible approaches to compute effectiveness factors: (a) integration as per definition versus (b) differentiation and nonlinear system. It is demonstrable that software performance is dependent on the approach, and that the differentiation approach yields better results.

Combinations of essential oils as effective green stabilizers for single base propellants
José Daniel Langendorf da Silva, Rodrigo Leonard Barboza Rodrigues, Rogério Rosato, Maurício Ferrapontoff Lemos, Letivan Mendonça Filho, Tanos Celmar Costa França, and Fernando Cunha Peixoto
Wiley
AbstractNitrocellulose‐based propellants undergo natural (and inevitable) autocatalytic degradation reactions. The presence of a stabilizer is essential to avoid and reduce the degradation reactions by capturing the NOx molecules. Traditional stabilizers, such as diphenylamine, and ethylcentralite, react with NOx through their amine and/or amide groups, leading to n‐nitroso groups, which are known to have carcinogenic, mutagenic and reprotoxic properties. Molecules that are not prone to form by‐products containing nitrosamines have been studied as substitutes, such as guaiacol and curcumin. However, the aromatic rings on these molecules have their acidity augmented when capturing the NOx groups and, paradoxically, increasing hydrolysis rates. In order to find a solution for the problem, we evaluated the use of essential oils containing terpenes and/or phenolic compounds to introduce a buffering capacity. Several propellant formulations with those compounds were subjected to traditional stability tests (German, Bergman–Junk and Storage tests), Pressure Vacuum Stability Test and Heat Flow Microcalorimetry. Finally, industrial batches were produced for the evaluation of real (ballistic) performance. Results indicated that the usage of essential oils increases stability properties not only through a sum of effects, but also in a synergistic way. Ballistic results were also adequate.

Determination of carbohydrates in brewer's wort by capillary electrophoresis with indirect UV detection
Rafaella Silva Aredes, Fernando Cunha Peixoto, Leandro Alcoforado Sphaier, Vinicius Nunes Henrique Silva, Lucas Mattos Duarte, and Flávia Ferreira de Carvalho Marques
Elsevier BV

Estimation of Thermochemical Properties of Propellants Using Peng-Robinson Equation of State
Luciana Amorim da Silva, Ana Carolina Marotti Dias, Hector Gabriel Teixeira Volskis, José Daniel Langendorf da Silva, Aline Cardoso Anastacio, and Fernando Cunha Peixoto
FapUNIFESP (SciELO)
Several aspects make nitrocellulose based powders adequate as a solid propellant for rockets and missiles and the prefe rable propellant to be used in firearms and artillery: it produces less smoke and less fouling than other propellants; its burning rate shows a well-defined relation to pressure and the composition of the gaseous mixture resulting from its decomposition by burning can be predicted with relatively high levels of accuracy. This last feature, if coupled with adequate thermodynamic models, leads to a reliable framework for the simulation of internal ballistics and, ultimately, to an efficient design. Some simpler models use an ideal gas approach, which is obviously not adequate, and some others perform corrections based on the Virial E quation of S tate for sake of algebraic simplicity. This work employs the Peng-Robinson equation of state to model the pressure-volume-temperature (PVT) behavior of the gases produced during the burning reaction, once it is known to be accurate in the high pressures obtained inside combustion chambers. The results were compared to experimental data obtained in a closed vessel device and showed that the Peng-Robinson equation of state could predict the chamber pressure with higher accuracy.

On the replacement of traditional stabilizers by guaiacol in environmentally safe nitrocellulose-based propellants
Rodrigo L. B. Rodrigues, Ana Paula da Silva, Rogério Rosato, Maurício F. Lemos, Fernando C. Peixoto, Tanos C. C. França, and Letivan G. Mendonça Filho
Springer Science and Business Media LLC

Long-Range Investment Assessment in a Petrochemical Industry: Cost and Safety Considerations
Karla M. Boaventura, Fernando C. Peixoto, Heloísa L.S. Fernandes, and Fernando L.P. Pessoa
Elsevier BV

Can green nitrocellulose-based propellants be made through the replacement of diphenylamine by the natural product curcumin?
Rodrigo Leonard Barboza Rodrigues, Pedro Augusto Gomes Buitrago, Nami Lavigne Nakano, Fernando Cunha Peixoto, Maurício Ferrapontoff Lemos, Tanos Celmar Costa França, and Letivan Gonçalvez Mendonça Filho
Informa UK Limited
ABSTRACT This research evaluates the feasibility of replacing diphenylamine (DPA) with the natural product curcumin as a stabilizer in samples of nitrocellulose-based (NC-based) propellants. The stability analysis was performed using heat flow calorimetry, as described in STANAG-4582, as well as the most traditional stability testing protocols: the German test, Bergmann–Junk test, and the Storage test. Ballistic parameters were evaluated using a closed vessel ballistic test and samples underwent Scanning Electron Microscopy (SEM). Also, the Pressure Vacuum Stability Test (PVST), Differential Scanning Calorimetry (DSC), and Isothermal Thermogravimetry (TG) to evaluate the homogeneity, stability, and compatibility with NC were performed. The ballistic parameters were evaluated using a closed vessel ballistic test. All samples of propellants stabilized with curcumin passed the stability test criteria performed in this research, with better scores than the propellant sample stabilized with DPA, which was used as a reference. However, the estimation of ballistic parameters indicated that the deflagration of the propellant stabilized with curcumin exhibits some delay when compared to the reference sample, which can be easily overcome by adjusting the propellant grain dimensions, especially the thickness. Finally, an HPLC analysis method was developed to identify and characterize this new Single-Based (SB) propellant stabilizer. This method was shown to be effective, fast, accurate, and adequate to comply with the stability criteria proposed by the AOP-48 standard, especially because of the depletion of the stabilizer concentration after artificial aging. We believe that our results are promising and support the proposal that curcumin can replace DPA as a stabilizer for SB propellants.

Etched fiber Bragg grating probe using a regular CNC machine and a 3D printer
Vicente A. Oliveira, Alexander C. Carneiro, Alexandre B. Dos Santos, Andrés Pablo L. Barbero, Fernando C. Peixoto, and Vinicius N. H. Silva
Optica Publishing Group
Etched fiber Bragg gratings (EFBGs) have been widely employed for refractive index (RI) measurements that can be used to monitor sugar consumption during the fermentation of alcoholic beverages. EFBGs are obtained by removing the cladding of a fiber Bragg grating, which is traditionally performed by a chemical attack with hydrogen fluoride, an extremely hazardous corrosive substance that causes severe wounds and even death. To overcome such drawbacks, this technical note presents a simple, practical, and low cost method for the diameter reduction of single mode optical fibers by mechanical polishing, employing a small scale computer numerical control device and an ad hoc 3D-printed rod. The sensor probe obtained was tested using sucrose aqueous solutions with RIs between 1.333 and 1.394, measured in an Abbe refractometer. The results show a linear shift of the Bragg wavelength with respect to RI with a correlation of 0.928.

Evaluation of craft beers through the direct determination of amino acids by capillary electrophoresis and principal component analysis
Rafaella Silva Aredes, Fernando Cunha Peixoto, Leandro Alcoforado Sphaier, and Flávia Ferreira de Carvalho Marques
Elsevier BV

Robust data reconciliation in chemical reactors
Alexandre Santuchi da Cunha, Fernando Cunha Peixoto, and Diego Martinez Prata
Computers and Chemical Engineering Elsevier BV

Real-Time Fermentation Monitoring of Synthetic Beer Wort Using Etched Fiber Bragg Grating
Vicente A. de Oliveira, Andres Pablo L. Barbero, Leandro A. Sphaier, Alexandre B. dos Santos, Fernando C. Peixoto, and Vinicius N. H. Silva
Institute of Electrical and Electronics Engineers (IEEE)
A refractometer based on an etched fiber Bragg gratings (EFBGs) sensor has been developed for monitoring beer fermentation in real time. The sensor was calibrated using synthetic solutions composed of water, maltose, and ethanol with alcohol by volume (ABV) ranging from 4.0% to 12.0% and Brix (sugar content) varying from 5% to 25%. Calibration results showed that the EFBG sensor responds with high sensitivity even to minor density variations less than 0.5 Brix ± 0.03 Brix in a quasi-linear monotonic fashion with respect to sugar and ethanol concentration, which allowed fitting an empirical model with good adherence to experimental data (low model variance) and with well-defined parameters (parameters covariance matrix with elements exhibiting small absolute values). Finally, the developed sensor was tested in a typical fermentation scenario. A rigorous material balance framework was established to relate the fit calibration model to actual density and alcohol content in real time, which is of assistance for process control strategies. As the proposed sensor can be fit in fermentation vessels for real-time (online) fermentation monitoring, it becomes a technological improvement to traditional offline measurements in terms of both biosafety and process control.

Interference in beer bitterness measurements caused by polymer tubes
Ivi Nascimento, Lucas Calado, Maria Eduarda Duncan, Bruna Trindade, Leandro Sphaier, Vinicius Silva, and Fernando Peixoto
Elsevier BV

Low-cost fluorescence-based method for beer bitterness measurement
L.S. Calado, A.L.F. Lacerda, S.B. Fiaux, L.A. Sphaier, V.N.H. Silva, and F.C. Peixoto
Elsevier BV

NMR relaxation and relaxivity parameters of MRI probes revealed by optimal wavelet signal compression of molecular dynamics simulations
Mateus A. Gonçalves, Lizandro S. Santos, Fernando C. Peixoto, and Teodorico C. Ramalho
Wiley

Conversion of glycerine into 1,2-propanediol for industrial applications
Gustavo N. Oliveira, Natane C. Barbosa, Felipe C. Araújo, Pedro H. G. Souza, André V. H. Soares, Fernando C. Peixoto, José W. M. Carneiro, and Fabio B. Passos
Springer Singapore

Integral transform analysis of heat and mass diffusion in chemically reacting systems with Michaelis–Menten kinetics
I.F. Pinheiro, H.L. Serrano, L.A. Sphaier, F.C. Peixoto, and V.N.H. Silva
Elsevier BV

Dynamic optimization of a continuous gas lift process using a mesh refining sequential method
Lizandro de Sousa Santos, Kaio Magno Ferreira de Souza, Marina Ribeiro Bandeira, Víctor Rolando Ruiz Ahón, Fernando Cunha Peixoto, and Diego Martinez Prata
Elsevier BV

Comparing Structure and Dynamics of Solvation of Different Iron Oxide Phases for Enhanced Magnetic Resonance Imaging
Mateus A. Gonçalves, Lizandro S. Santos, Fernando C. Peixoto, Elaine F. F. da Cunha, Telles C. Silva, and Teodorico C. Ramalho
Wiley

Robust data reconciliation in a chemical reactor through simulated annealing optimization

Optimal wavelet signal compression as an efficient alternative to investigate molecular dynamics simulations: application to thermal and solvent effects of MRI probes
Mateus A. Gonçalves, Lizandro S. Santos, Diego M. Prata, Fernando C. Peixoto, Elaine F. F. da Cunha, and Teodorico C. Ramalho
Springer Science and Business Media LLC

A study of equivalent electrical circuit fitting to electrochemical impedance using a stochastic method
Marco André Abud Kappel, Fernando Cunha Peixoto, Gustavo Mendes Platt, Roberto Pinheiro Domingos, and Ivan Napoleão Bastos
Elsevier BV

Fernando Cunha Peixoto

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Scopus Publications