Alan Vieira - Academia.edu (original) (raw)

Papers by Alan Vieira

Research paper thumbnail of Evaluation of the influence of the position of the syringe during the management of pasteurized human milk

Objetivo: evaluar si la posicion de la jeringa durante la administracion de la leche humana paste... more Objetivo: evaluar si la posicion de la jeringa durante la administracion de la leche humana pasteurizada para gastroclise interfiere en concentraciones finales de macronutrientes, especialmente en concentraciones de grasa. Metodo: ensayo clinico controlado, ciego, donde se compararon las concentraciones de grasas, proteinas e carbohidratos de la leche humana pasteurizada despues de su administracion, a traves de gastroclise. Las muestras de 20 ml de leche humana pasteurizada se homogeneizaron y se separaron en dos alicuotas de 10 ml cada una. Se calculo un n de muestra de 49 muestras y las concentraciones de macronutrientes se compararon mediante la prueba t-pareada y expresadas como medidas de tendencia central. Se utilizo el paquete estadistico SPSS 16.0. La investigacion fue aprobada por el Comite de Etica en Investigacion del HUAP/UFF, protocolo no 189/2011. Resultados: las concentraciones de grasa obtenidas despues de gastroclise realizada con jeringas en posicion horizontal fu...

Research paper thumbnail of Nutrição e crescimento do recém-nascido de muito baixo peso: um desafio para a prática perinatal

... MUITO BAIXO PESO – UM DESAFIO PARA A PRÁTICA PERINATAL. ALAN ARAÚJO VIEIRA Rio de Janeiro, ju... more ... MUITO BAIXO PESO – UM DESAFIO PARA A PRÁTICA PERINATAL. ALAN ARAÚJO VIEIRA Rio de Janeiro, junho de 2005. Page 2. 2 ... Ciências, área de concentração: neonatologia. AlanAraújo Vieira Orientadora: Dra. Maria Elizabeth Lopes Moreira ...

Research paper thumbnail of Fast spark discharge-laser-induced breakdown spectroscopy method for rice botanic origin determination

Food chemistry, 2020

A simple, fast, and efficient spark discharge-laser-induced breakdown spectroscopy (SD-LIBS) meth... more A simple, fast, and efficient spark discharge-laser-induced breakdown spectroscopy (SD-LIBS) method was developed for determining rice botanic origin using predictive modeling based on support vector machine (SVM). Seventy-two samples from four rice varieties (Guri, Irga 424, Puitá, and Taim) were analyzed by SD-LIBS. Spectral lines of C, Ca, Fe, Mg, N and Na were selected as input variables for prediction model fitting. The SVM algorithm parameters were optimized using a central composite design (CCD) to find the better classification performance. The optimum model for discriminating rice samples according to their botanical variety was obtained using C = 5.25 and γ = 0.119. This model achieved 96.4% of correct predictions in test samples and showed sensitivities and specificities per class within the range of 92-100%. The developed method is robust and eco-friendly for rice botanic identification since its prediction results are consistent and reproducible and its application does...

Research paper thumbnail of Fatores perinatais relacionados à falha da pressão positiva contínua nasal precoce em recém-nascidos de muito baixo-peso

Recém-nascido de muito baixo-peso; Pressão positiva contínua nas vias aéreas; Terapia respiratóri... more Recém-nascido de muito baixo-peso; Pressão positiva contínua nas vias aéreas; Terapia respiratória; Fatores de risco.

Research paper thumbnail of Aperfeiçoamento e avaliação de um novo sistema de digestão assistida por aquecimento condutivo em frasco fechado para preparar amostras de carne “in natura” para análise elementar

Research paper thumbnail of Influence of different breast expression techniques on human colostrum macronutrient concentrations

Journal of Perinatology

To evaluate the effects of breast expression methods on macronutrient and caloric concentrations ... more To evaluate the effects of breast expression methods on macronutrient and caloric concentrations in human colostrum. A cross-sectional study in which colostrum samples were collected simultaneously from each breast using different milk expression methods, including manual expression or electric pumping, assigned by simple randomization. Macronutrients were measured by infrared spectroscopy, and their concentrations were compared by the Wilcoxon test. Ninety-six samples from each breast of selected donors were evaluated. There were no differences in carbohydrate (6.1 vs. 6.1 g/dL; p: 0.218) and protein (2.1 vs. 2.1 g/dL; p: 0.772) concentrations between the samples collected by manual expression and electric pumping. However, in those collected by manual expression, lipid concentrations (2.6 vs. 2.2 g/dL; p < 0.001) and caloric content (60 vs. 57 Kcal/dL; p = 0.001) were higher. Colostrum collected by hand expression had a higher lipid concentration and caloric content than that collected by an electric pump.

Research paper thumbnail of Back to the medical classes-Part I- Strategy for return to the presential practices during COVID-19 pandemics in a Brazilian Medical School

Introduction: In Brazil, practices of medical students have been interrupted due to COVID-19 to m... more Introduction: In Brazil, practices of medical students have been interrupted due to COVID-19 to meet emergency demands. Aim: To describe a strategy for a controlled return to the presential practices for medical students. Methods: We developed a standardized protocol to be applied before and during the return of the practical classes in medical students of Universidade Federal Fluminense, in the follow months after COVID-19 pandemic beginning. The protocol was comprised in three parts: Remote training on COVID-19 prevention; Face-to-face training focused in COVID-19 prevention, handwashing and personal protective equipment use; Investigation of students COVID-19 status before starting practical activities and weekly monitoring for COVID-19 during seven weeks. The training was done by medical teachers in small groups for medical students of the last lective semester. Results: The classes were interrupted on March 12, 2020 and returned in August 10, 2020. Seventy-one students were tra...

Research paper thumbnail of Retinopathy of prematurity and telemedicine in developing countries

Journal of American Association for Pediatric Ophthalmology and Strabismus

Research paper thumbnail of Construção De Uma Bomba Peristáltica e De Um Sistema De Detecção Utilizando Um Hardware De Código Fonte Aberto “Arduino” Para Análise Em Fluxo

Química Nova

This work describes the development of a peristaltic pump and a photometric detector, using "Ardu... more This work describes the development of a peristaltic pump and a photometric detector, using "Arduino" and alternative and low-cost materials for flow analysis system. The analytical calibration curve of the acid-red-283 using the proposed system presents 0.9984 and 3.9% as the coefficients of determination and variation, and 1.1 and 3.8 mg L-1 as limits of detection and quantification, respectively. Three prepared samples of the acid-red-283 (25, 30 and 35 mg L-1) showed recovery between 99 to 104%. For construction of the peristaltic pump and the photometer using Light Emitting Diodes (LED), light-dependent resistor (LDR) were spent less than 10% of the cost was spent on a commercial system employing a peristaltic pump and a spectrophotometer. Furthermore, the peristaltic pump and the photometer developed in this work allow the implementation of practical disciplines, such as molecular absorption spectrophotometry and flow analysis system in undergraduate courses, making these instruments more accessible, especially for the chemistry students.

Research paper thumbnail of Comparação entre os resultados do teste da orelhinha e da timpanometria: Devemos revisar o protocolo de triagem auditiva neonatal?

Revista de Pediatria SOPERJ

Comparação entre os resultados do teste da orelhinha e da timpanometria: devemos revisar o protoc... more Comparação entre os resultados do teste da orelhinha e da timpanometria: devemos revisar o protocolo de triagem auditiva neonatal? Comparison of the results of the otoacoustic emission tests and tympanometry tests: should we revise the neonatal hearing screening protocol?

Research paper thumbnail of Evaluation of an improved closed-vessel conductively heated digestion system for the analysis of raw meat samples by ICP techniques

Journal of Analytical Atomic Spectrometry

In this work, an improved conductively heated digestion system (CHDS) with closed vessels, which ... more In this work, an improved conductively heated digestion system (CHDS) with closed vessels, which provides simpler, easier and safer digestion of raw chicken, beef and pork meat samples aiming at Ca, Cu, Fe, K, Mg, Mn, Na, P, S, and Zn determinations by ICP OES and As, Cd, Cr, Mo, Pb and Se by ICP-MS/MS, was evaluated.

Research paper thumbnail of A user-friendly excel spreadsheet for dealing with spectroscopic and chromatographic data

Chemometrics and Intelligent Laboratory Systems

Abstract A user-friendly interface was developed in Excel (Microsoft Office) to deal with spectro... more Abstract A user-friendly interface was developed in Excel (Microsoft Office) to deal with spectroscopic and chromatographic data. The Excel spreadsheet includes baseline correction, area and height determination, and identification of variables that represent the maximum height. In addition, the user can quickly evaluate standardization methods and create databases by adding information to the library, where up to 300 peaks can be saved. In the present work, the application of the Excel spreadsheet is exemplified by analytical curves developed with gas chromatography, Raman spectroscopy and laser-induced breakdown spectroscopy (LIBS) data. The analytical parameters obtained by the Excel spreadsheet were compared with the results generated in different software, such as MATLAB (routine), Origin and ChromQuest. The coefficient of determination (R2) and root-mean-square error (RMSE) obtained from Excel spreadsheet were very similar to those from other software. The analytical curves were also submitted to analysis of variance (ANOVA) and, regarding the F-test, all presented values of Fcalculated greater than Fcritical. The relationship between the analytical responses from the Excel spreadsheet and other software showed a coefficient of correlation close to 1. Therefore, the proposed Excel interface is an attractive alternative to expensive software and provides easy handling for LIBS data. The spreadsheet and a short tutorial video are available in the electronic supplementary material (or in the link https://1drv.ms/f/s!AjTI1LyRsk35lYtYOvj6EGyXvFgWlQ).

Research paper thumbnail of Multi-energy calibration for the determination of non-metals by high-resolution continuum source molecular absorption spectrometry

Journal of Analytical Atomic Spectrometry

Spectra of diatomic molecules are rich in fine structures which may be used for different analyti... more Spectra of diatomic molecules are rich in fine structures which may be used for different analytical applications in high-resolution continuum source molecular absorption spectrometry (HR-CS MAS).

Research paper thumbnail of The antibacterial activity of rhamnolipid biosurfactant is pH dependent

Food Research International

Rhamnolipid (RL) biosurfactants have been studied as agents to control the growth of food pathoge... more Rhamnolipid (RL) biosurfactants have been studied as agents to control the growth of food pathogens however, to be successful applied as antimicrobial agent in food, is important to determine the effect of environmental conditions on RL activity. Once pH is a determinant factor to the development of microorganisms in food, we investigated the antimicrobial activity of RL under different pH values. The antimicrobial activity of RL against the Gram-positive pathogens L. monocytogenes, B. cereus and S. aureus was pH dependent and favored at more acidic conditions while the Gram-negative Salmonella enterica and E. coli (EHEC) showed resistance at all pH levels studied. Bacillus cereus was the most sensitive bacteria showing MIC of 19.5 μg/mL and eradication of the population was observed after 30 min with 39.1 μg/mL of RL. The sensitivity to RL was associated with reduction on cell surface hydrophobicity and cytoplasmic membrane damage. Scanning Electron Microscopy images evidenced the cell damage promoted by RL on sensitive strains. The pH is an important factor to be considered on developing RL-based strategies to the control of food pathogens.

Research paper thumbnail of Determinations of phosphorus in fertilizers by spark discharge-assisted laser-induced breakdown spectroscopy

Microchemical Journal

A spark discharge system was coupled to laser-induced breakdown spectroscopy (SD-LIBS) to improve... more A spark discharge system was coupled to laser-induced breakdown spectroscopy (SD-LIBS) to improve sensitivity in the determination of P in fertilizers. A LIBS system consisting of a Q-switched Nd:YAG laser operating at 1064 nm and emitting pulses at 50 mJ with a fluence of 70 J cm −2 at the focal point was used. Results of preliminary experiments suggested that the most appropriate wavelength to measure P was the P (I) line at 214.9 nm, which did not show interferences by Fe, Cu and Zn. The electrical discharge was provided by a homemade highvoltage electronic circuit consisting of two cylindrical tungsten electrodes at the optimized output voltage of 4.5 kV, with tips arranged at the optimal distances of 4 mm between them and 2 mm above the sample surface. To minimize the expected matrix effects calibration standards of P 2 O 5 in the range of 4.8 and 33.3% were prepared by mixing various amounts of a phosphate rock reference material (SRM-120c) with a mixture of CaCO 3 , CaSO 4 , (NH 2) 2 CO and KCl at a 1:1:1:1 mass ratio. The calibration curves obtained at a 4.5 kV SD-LIBS output voltage showed correlation coefficients ≥0.993, RSD ≤8% and LOQ 5.3% (m/m) P 2 O 5. Data obtained by analyzing commercial samples by the proposed system were in good agreement, at 95% confidence level, with those obtained by using high-resolution continuum-source flame atomic absorption spectroscopy.

Research paper thumbnail of Expanding the potentialities of standard dilution analysis: Determination of ethanol in gasoline by Raman spectroscopy

Microchemical Journal

This work describes the application of standard dilution analysis (SDA) in Raman spectroscopy, de... more This work describes the application of standard dilution analysis (SDA) in Raman spectroscopy, demonstrating the versatility of this new calibration method. A flow system (FA) was developed for ethanol determination in gasoline employing liquid-liquid extraction (LLE) and acetone as the internal standard (IS). Applying LLE eliminated the intense fluorescence background, allowing for ethanol determination using a portable 785-nm-laser Raman system. The SDA-LLE-FA method was applied to commercial gasoline samples and the results were compared with values obtained using the ABNT NBR 13992 reference method. No statistically significant differences were observed for ethanol concentrations determined using the two methods (paired t-test at the 95% confidence level). SDA's accuracy was also evaluated by comparing results from analyses using the same LLE-FA system combined with the traditional calibration methods of matrix matching (MM), standard additions (SA) and internal standardization (IS). Recoveries from spike experiments were in 98.6-104.1% (SDA-LLE-FA), 94.7-171.1% (ABNT NBR 13992), 106.8-114.1% (MM-LLE-FA), 103.7-108.4% (IS-LLE-FA), and 114.7-125.8% (SA-LLE-FA) range. The relative standard deviation (RSD, n = 12, 25.5% v/v −1 ethanol in gasoline), limits of detection and quantification calculated for the SDA-LLE-FA method were 2%, 0.5% and 1.8% (v/v −1), respectively.

Research paper thumbnail of Plastia mitral cir�rgica em crian�as com febre reum�tica

Research paper thumbnail of Implementation of a protocol for antibiotic use in very low birth weight infants

Jornal De Pediatria, Jul 16, 2013

Research paper thumbnail of 3ª Fase - GERENCIAMENTO DE CLIENTES DE UMA PETSHOP A PARTIR DA UTILIZAÇÃO DAS COLLECTIONS DO JAVA

Anais Sulcomp, Sep 21, 2010

Research paper thumbnail of Interference of heart and transcutaneous oxygen monitoring in the measurement of bioelectrical impedance analysis in preterm newborns

Jornal de Pediatria, 2016

Objective: To verify if the connection of electrodes for heart and transcutaneous oxygen monitori... more Objective: To verify if the connection of electrodes for heart and transcutaneous oxygen monitoring interfere with the measurement of electrical bioimpedance in preterm newborns. Methods: This was a prospective, blinded, controlled, cross-sectional, crossover study that assessed and compared paired measures of resistance (R) and reactance (Xc) by BIA, obtained with and without monitoring wires attached to the preterm newborn. The measurements were performed in immediate sequence, after randomization to the presence or absence of electrodes. The sample size calculated was 114 measurements or tests with monitoring wires and 114 without monitoring wires, considering for a difference between the averages of 0.1 ohms, with an alpha error of 10% and beta error of 20%, with significance <0.05. Results: No differences were observed between the R (677.37 ± 196.07 vs. 677.46 ± 194.86) and Xc (31.15 ± 9.36 vs. 31.01 ± 9.56) values obtained with and without monitoring wires, respectively, with good correlation between them (R: 0.997 and Xc: 0.968).

Research paper thumbnail of Evaluation of the influence of the position of the syringe during the management of pasteurized human milk

Objetivo: evaluar si la posicion de la jeringa durante la administracion de la leche humana paste... more Objetivo: evaluar si la posicion de la jeringa durante la administracion de la leche humana pasteurizada para gastroclise interfiere en concentraciones finales de macronutrientes, especialmente en concentraciones de grasa. Metodo: ensayo clinico controlado, ciego, donde se compararon las concentraciones de grasas, proteinas e carbohidratos de la leche humana pasteurizada despues de su administracion, a traves de gastroclise. Las muestras de 20 ml de leche humana pasteurizada se homogeneizaron y se separaron en dos alicuotas de 10 ml cada una. Se calculo un n de muestra de 49 muestras y las concentraciones de macronutrientes se compararon mediante la prueba t-pareada y expresadas como medidas de tendencia central. Se utilizo el paquete estadistico SPSS 16.0. La investigacion fue aprobada por el Comite de Etica en Investigacion del HUAP/UFF, protocolo no 189/2011. Resultados: las concentraciones de grasa obtenidas despues de gastroclise realizada con jeringas en posicion horizontal fu...

Research paper thumbnail of Nutrição e crescimento do recém-nascido de muito baixo peso: um desafio para a prática perinatal

... MUITO BAIXO PESO – UM DESAFIO PARA A PRÁTICA PERINATAL. ALAN ARAÚJO VIEIRA Rio de Janeiro, ju... more ... MUITO BAIXO PESO – UM DESAFIO PARA A PRÁTICA PERINATAL. ALAN ARAÚJO VIEIRA Rio de Janeiro, junho de 2005. Page 2. 2 ... Ciências, área de concentração: neonatologia. AlanAraújo Vieira Orientadora: Dra. Maria Elizabeth Lopes Moreira ...

Research paper thumbnail of Fast spark discharge-laser-induced breakdown spectroscopy method for rice botanic origin determination

Food chemistry, 2020

A simple, fast, and efficient spark discharge-laser-induced breakdown spectroscopy (SD-LIBS) meth... more A simple, fast, and efficient spark discharge-laser-induced breakdown spectroscopy (SD-LIBS) method was developed for determining rice botanic origin using predictive modeling based on support vector machine (SVM). Seventy-two samples from four rice varieties (Guri, Irga 424, Puitá, and Taim) were analyzed by SD-LIBS. Spectral lines of C, Ca, Fe, Mg, N and Na were selected as input variables for prediction model fitting. The SVM algorithm parameters were optimized using a central composite design (CCD) to find the better classification performance. The optimum model for discriminating rice samples according to their botanical variety was obtained using C = 5.25 and γ = 0.119. This model achieved 96.4% of correct predictions in test samples and showed sensitivities and specificities per class within the range of 92-100%. The developed method is robust and eco-friendly for rice botanic identification since its prediction results are consistent and reproducible and its application does...

Research paper thumbnail of Fatores perinatais relacionados à falha da pressão positiva contínua nasal precoce em recém-nascidos de muito baixo-peso

Recém-nascido de muito baixo-peso; Pressão positiva contínua nas vias aéreas; Terapia respiratóri... more Recém-nascido de muito baixo-peso; Pressão positiva contínua nas vias aéreas; Terapia respiratória; Fatores de risco.

Research paper thumbnail of Aperfeiçoamento e avaliação de um novo sistema de digestão assistida por aquecimento condutivo em frasco fechado para preparar amostras de carne “in natura” para análise elementar

Research paper thumbnail of Influence of different breast expression techniques on human colostrum macronutrient concentrations

Journal of Perinatology

To evaluate the effects of breast expression methods on macronutrient and caloric concentrations ... more To evaluate the effects of breast expression methods on macronutrient and caloric concentrations in human colostrum. A cross-sectional study in which colostrum samples were collected simultaneously from each breast using different milk expression methods, including manual expression or electric pumping, assigned by simple randomization. Macronutrients were measured by infrared spectroscopy, and their concentrations were compared by the Wilcoxon test. Ninety-six samples from each breast of selected donors were evaluated. There were no differences in carbohydrate (6.1 vs. 6.1 g/dL; p: 0.218) and protein (2.1 vs. 2.1 g/dL; p: 0.772) concentrations between the samples collected by manual expression and electric pumping. However, in those collected by manual expression, lipid concentrations (2.6 vs. 2.2 g/dL; p < 0.001) and caloric content (60 vs. 57 Kcal/dL; p = 0.001) were higher. Colostrum collected by hand expression had a higher lipid concentration and caloric content than that collected by an electric pump.

Research paper thumbnail of Back to the medical classes-Part I- Strategy for return to the presential practices during COVID-19 pandemics in a Brazilian Medical School

Introduction: In Brazil, practices of medical students have been interrupted due to COVID-19 to m... more Introduction: In Brazil, practices of medical students have been interrupted due to COVID-19 to meet emergency demands. Aim: To describe a strategy for a controlled return to the presential practices for medical students. Methods: We developed a standardized protocol to be applied before and during the return of the practical classes in medical students of Universidade Federal Fluminense, in the follow months after COVID-19 pandemic beginning. The protocol was comprised in three parts: Remote training on COVID-19 prevention; Face-to-face training focused in COVID-19 prevention, handwashing and personal protective equipment use; Investigation of students COVID-19 status before starting practical activities and weekly monitoring for COVID-19 during seven weeks. The training was done by medical teachers in small groups for medical students of the last lective semester. Results: The classes were interrupted on March 12, 2020 and returned in August 10, 2020. Seventy-one students were tra...

Research paper thumbnail of Retinopathy of prematurity and telemedicine in developing countries

Journal of American Association for Pediatric Ophthalmology and Strabismus

Research paper thumbnail of Construção De Uma Bomba Peristáltica e De Um Sistema De Detecção Utilizando Um Hardware De Código Fonte Aberto “Arduino” Para Análise Em Fluxo

Química Nova

This work describes the development of a peristaltic pump and a photometric detector, using "Ardu... more This work describes the development of a peristaltic pump and a photometric detector, using "Arduino" and alternative and low-cost materials for flow analysis system. The analytical calibration curve of the acid-red-283 using the proposed system presents 0.9984 and 3.9% as the coefficients of determination and variation, and 1.1 and 3.8 mg L-1 as limits of detection and quantification, respectively. Three prepared samples of the acid-red-283 (25, 30 and 35 mg L-1) showed recovery between 99 to 104%. For construction of the peristaltic pump and the photometer using Light Emitting Diodes (LED), light-dependent resistor (LDR) were spent less than 10% of the cost was spent on a commercial system employing a peristaltic pump and a spectrophotometer. Furthermore, the peristaltic pump and the photometer developed in this work allow the implementation of practical disciplines, such as molecular absorption spectrophotometry and flow analysis system in undergraduate courses, making these instruments more accessible, especially for the chemistry students.

Research paper thumbnail of Comparação entre os resultados do teste da orelhinha e da timpanometria: Devemos revisar o protocolo de triagem auditiva neonatal?

Revista de Pediatria SOPERJ

Comparação entre os resultados do teste da orelhinha e da timpanometria: devemos revisar o protoc... more Comparação entre os resultados do teste da orelhinha e da timpanometria: devemos revisar o protocolo de triagem auditiva neonatal? Comparison of the results of the otoacoustic emission tests and tympanometry tests: should we revise the neonatal hearing screening protocol?

Research paper thumbnail of Evaluation of an improved closed-vessel conductively heated digestion system for the analysis of raw meat samples by ICP techniques

Journal of Analytical Atomic Spectrometry

In this work, an improved conductively heated digestion system (CHDS) with closed vessels, which ... more In this work, an improved conductively heated digestion system (CHDS) with closed vessels, which provides simpler, easier and safer digestion of raw chicken, beef and pork meat samples aiming at Ca, Cu, Fe, K, Mg, Mn, Na, P, S, and Zn determinations by ICP OES and As, Cd, Cr, Mo, Pb and Se by ICP-MS/MS, was evaluated.

Research paper thumbnail of A user-friendly excel spreadsheet for dealing with spectroscopic and chromatographic data

Chemometrics and Intelligent Laboratory Systems

Abstract A user-friendly interface was developed in Excel (Microsoft Office) to deal with spectro... more Abstract A user-friendly interface was developed in Excel (Microsoft Office) to deal with spectroscopic and chromatographic data. The Excel spreadsheet includes baseline correction, area and height determination, and identification of variables that represent the maximum height. In addition, the user can quickly evaluate standardization methods and create databases by adding information to the library, where up to 300 peaks can be saved. In the present work, the application of the Excel spreadsheet is exemplified by analytical curves developed with gas chromatography, Raman spectroscopy and laser-induced breakdown spectroscopy (LIBS) data. The analytical parameters obtained by the Excel spreadsheet were compared with the results generated in different software, such as MATLAB (routine), Origin and ChromQuest. The coefficient of determination (R2) and root-mean-square error (RMSE) obtained from Excel spreadsheet were very similar to those from other software. The analytical curves were also submitted to analysis of variance (ANOVA) and, regarding the F-test, all presented values of Fcalculated greater than Fcritical. The relationship between the analytical responses from the Excel spreadsheet and other software showed a coefficient of correlation close to 1. Therefore, the proposed Excel interface is an attractive alternative to expensive software and provides easy handling for LIBS data. The spreadsheet and a short tutorial video are available in the electronic supplementary material (or in the link https://1drv.ms/f/s!AjTI1LyRsk35lYtYOvj6EGyXvFgWlQ).

Research paper thumbnail of Multi-energy calibration for the determination of non-metals by high-resolution continuum source molecular absorption spectrometry

Journal of Analytical Atomic Spectrometry

Spectra of diatomic molecules are rich in fine structures which may be used for different analyti... more Spectra of diatomic molecules are rich in fine structures which may be used for different analytical applications in high-resolution continuum source molecular absorption spectrometry (HR-CS MAS).

Research paper thumbnail of The antibacterial activity of rhamnolipid biosurfactant is pH dependent

Food Research International

Rhamnolipid (RL) biosurfactants have been studied as agents to control the growth of food pathoge... more Rhamnolipid (RL) biosurfactants have been studied as agents to control the growth of food pathogens however, to be successful applied as antimicrobial agent in food, is important to determine the effect of environmental conditions on RL activity. Once pH is a determinant factor to the development of microorganisms in food, we investigated the antimicrobial activity of RL under different pH values. The antimicrobial activity of RL against the Gram-positive pathogens L. monocytogenes, B. cereus and S. aureus was pH dependent and favored at more acidic conditions while the Gram-negative Salmonella enterica and E. coli (EHEC) showed resistance at all pH levels studied. Bacillus cereus was the most sensitive bacteria showing MIC of 19.5 μg/mL and eradication of the population was observed after 30 min with 39.1 μg/mL of RL. The sensitivity to RL was associated with reduction on cell surface hydrophobicity and cytoplasmic membrane damage. Scanning Electron Microscopy images evidenced the cell damage promoted by RL on sensitive strains. The pH is an important factor to be considered on developing RL-based strategies to the control of food pathogens.

Research paper thumbnail of Determinations of phosphorus in fertilizers by spark discharge-assisted laser-induced breakdown spectroscopy

Microchemical Journal

A spark discharge system was coupled to laser-induced breakdown spectroscopy (SD-LIBS) to improve... more A spark discharge system was coupled to laser-induced breakdown spectroscopy (SD-LIBS) to improve sensitivity in the determination of P in fertilizers. A LIBS system consisting of a Q-switched Nd:YAG laser operating at 1064 nm and emitting pulses at 50 mJ with a fluence of 70 J cm −2 at the focal point was used. Results of preliminary experiments suggested that the most appropriate wavelength to measure P was the P (I) line at 214.9 nm, which did not show interferences by Fe, Cu and Zn. The electrical discharge was provided by a homemade highvoltage electronic circuit consisting of two cylindrical tungsten electrodes at the optimized output voltage of 4.5 kV, with tips arranged at the optimal distances of 4 mm between them and 2 mm above the sample surface. To minimize the expected matrix effects calibration standards of P 2 O 5 in the range of 4.8 and 33.3% were prepared by mixing various amounts of a phosphate rock reference material (SRM-120c) with a mixture of CaCO 3 , CaSO 4 , (NH 2) 2 CO and KCl at a 1:1:1:1 mass ratio. The calibration curves obtained at a 4.5 kV SD-LIBS output voltage showed correlation coefficients ≥0.993, RSD ≤8% and LOQ 5.3% (m/m) P 2 O 5. Data obtained by analyzing commercial samples by the proposed system were in good agreement, at 95% confidence level, with those obtained by using high-resolution continuum-source flame atomic absorption spectroscopy.

Research paper thumbnail of Expanding the potentialities of standard dilution analysis: Determination of ethanol in gasoline by Raman spectroscopy

Microchemical Journal

This work describes the application of standard dilution analysis (SDA) in Raman spectroscopy, de... more This work describes the application of standard dilution analysis (SDA) in Raman spectroscopy, demonstrating the versatility of this new calibration method. A flow system (FA) was developed for ethanol determination in gasoline employing liquid-liquid extraction (LLE) and acetone as the internal standard (IS). Applying LLE eliminated the intense fluorescence background, allowing for ethanol determination using a portable 785-nm-laser Raman system. The SDA-LLE-FA method was applied to commercial gasoline samples and the results were compared with values obtained using the ABNT NBR 13992 reference method. No statistically significant differences were observed for ethanol concentrations determined using the two methods (paired t-test at the 95% confidence level). SDA's accuracy was also evaluated by comparing results from analyses using the same LLE-FA system combined with the traditional calibration methods of matrix matching (MM), standard additions (SA) and internal standardization (IS). Recoveries from spike experiments were in 98.6-104.1% (SDA-LLE-FA), 94.7-171.1% (ABNT NBR 13992), 106.8-114.1% (MM-LLE-FA), 103.7-108.4% (IS-LLE-FA), and 114.7-125.8% (SA-LLE-FA) range. The relative standard deviation (RSD, n = 12, 25.5% v/v −1 ethanol in gasoline), limits of detection and quantification calculated for the SDA-LLE-FA method were 2%, 0.5% and 1.8% (v/v −1), respectively.

Research paper thumbnail of Plastia mitral cir�rgica em crian�as com febre reum�tica

Research paper thumbnail of Implementation of a protocol for antibiotic use in very low birth weight infants

Jornal De Pediatria, Jul 16, 2013

Research paper thumbnail of 3ª Fase - GERENCIAMENTO DE CLIENTES DE UMA PETSHOP A PARTIR DA UTILIZAÇÃO DAS COLLECTIONS DO JAVA

Anais Sulcomp, Sep 21, 2010

Research paper thumbnail of Interference of heart and transcutaneous oxygen monitoring in the measurement of bioelectrical impedance analysis in preterm newborns

Jornal de Pediatria, 2016

Objective: To verify if the connection of electrodes for heart and transcutaneous oxygen monitori... more Objective: To verify if the connection of electrodes for heart and transcutaneous oxygen monitoring interfere with the measurement of electrical bioimpedance in preterm newborns. Methods: This was a prospective, blinded, controlled, cross-sectional, crossover study that assessed and compared paired measures of resistance (R) and reactance (Xc) by BIA, obtained with and without monitoring wires attached to the preterm newborn. The measurements were performed in immediate sequence, after randomization to the presence or absence of electrodes. The sample size calculated was 114 measurements or tests with monitoring wires and 114 without monitoring wires, considering for a difference between the averages of 0.1 ohms, with an alpha error of 10% and beta error of 20%, with significance <0.05. Results: No differences were observed between the R (677.37 ± 196.07 vs. 677.46 ± 194.86) and Xc (31.15 ± 9.36 vs. 31.01 ± 9.56) values obtained with and without monitoring wires, respectively, with good correlation between them (R: 0.997 and Xc: 0.968).