Pub Date : 2023-03-03DOI: 10.21577/0100-4042.20170943
K. Silva, G. Caldeira, K. Nogueira, M. Canela, P. Filgueiras, Murilo Souza
COFFEE WITH CHEMOMETRIC: AN APPLICATION OF 25-1 FRACTIONAL FACTORIAL DESIGN. Chemometrics is a subfield of chemistry that emerged from advances in analytical instrumentation and computing. When seeking to solve chemical problems that depend on many concomitants experimental variables, chemometrics can be employed in order to extract as much information as possible in the least possible number of experiments. In addition, it is possible to evaluate the important effects and interactions among the variables to understand the processes being monitored in each system. In this sense, this article aimed to develop a didactic experiment of caffeine extraction using an espresso machine, applying the 25-1 fractional factorial design. The variables studied were temperature (75 and 78 ºC), pressure (2 and 15 bar), granulation (bean and ground), type of coffee (special and traditional) and period of the day (morning and afternoon) to obtain maximum extraction of caffeine. The coffee extracts obtained were analyzed using UV-Vis molecular absorption spectrophotometry. The developed experiment showed the potential to spread the application of chemometrics in the academic environment and to facilitate the teaching of fractional factorial design.
{"title":"CAFÉ COM QUIMIOMETRIA: UMA APLICAÇÃO DO PLANEJAMENTO FATORIAL FRACIONÁRIO 25-1","authors":"K. Silva, G. Caldeira, K. Nogueira, M. Canela, P. Filgueiras, Murilo Souza","doi":"10.21577/0100-4042.20170943","DOIUrl":"https://doi.org/10.21577/0100-4042.20170943","url":null,"abstract":"COFFEE WITH CHEMOMETRIC: AN APPLICATION OF 25-1 FRACTIONAL FACTORIAL DESIGN. Chemometrics is a subfield of chemistry that emerged from advances in analytical instrumentation and computing. When seeking to solve chemical problems that depend on many concomitants experimental variables, chemometrics can be employed in order to extract as much information as possible in the least possible number of experiments. In addition, it is possible to evaluate the important effects and interactions among the variables to understand the processes being monitored in each system. In this sense, this article aimed to develop a didactic experiment of caffeine extraction using an espresso machine, applying the 25-1 fractional factorial design. The variables studied were temperature (75 and 78 ºC), pressure (2 and 15 bar), granulation (bean and ground), type of coffee (special and traditional) and period of the day (morning and afternoon) to obtain maximum extraction of caffeine. The coffee extracts obtained were analyzed using UV-Vis molecular absorption spectrophotometry. The developed experiment showed the potential to spread the application of chemometrics in the academic environment and to facilitate the teaching of fractional factorial design.","PeriodicalId":49641,"journal":{"name":"Quimica Nova","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68267740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-03DOI: 10.21577/0100-4042.20170954
D. Pinto, Gabriela Lobato De Souza, Paulo Pitasse-Santos, A. Velez, Debora Decote-Ricardo, Debora Duarte Dos Santos, Leonardo Freire-de-Lima, Célio Freire-de-Lima, Marco de Lima
THE POTENTIAL OF NATURAL XANTHONE α-MANGOSTIN IN THE DEVELOPMENT OF NOVEL ANTIINFECTIVE AGENTS: A REVIEW. The mangosteen (Garcinia mangostana, Linn.) is a tropical fruit cultivated in the tropical forests of Southeast Asian countries. It is recognized as the queen of fruits due to its unique color, aroma, and flavor. It has been used for centuries in Southeastern Asian traditional medicine for the treatment of various diseases. Many functional molecules with high medicinal value are obtained from the pericarp of mangosteen fruit, whose major constituent is xanthone α-mangostin. Several studies have been carried out over the last decades to further investigate and understand the pharmacological properties associated with the plant and its main chemical constituents, belonging to the class of xanthones. In addition, numerous in vitro and in vivo studies related to mangosteen have been published, indicating its importance and its potential application in medicinal chemistry. Prenylated xanthones, which include α-mangostin, are secondary metabolites particularly common in plants belonging to the Clusiaceae family. These substances have been intensively investigated for their potential as biologically active agents. This article describes a critical analysis of published data related to the properties of α-mangostin, aiming to provide a more detailed view of its potential as a chemotherapeutic agent for the prevention and treatment of infectious diseases.
{"title":"O POTENCIAL DA XANTONA NATURAL α-MANGOSTINA NO DESENVOLVIMENTO DE NOVOS AGENTES ANTI-INFECCIOSOS: UMA REVISÃO","authors":"D. Pinto, Gabriela Lobato De Souza, Paulo Pitasse-Santos, A. Velez, Debora Decote-Ricardo, Debora Duarte Dos Santos, Leonardo Freire-de-Lima, Célio Freire-de-Lima, Marco de Lima","doi":"10.21577/0100-4042.20170954","DOIUrl":"https://doi.org/10.21577/0100-4042.20170954","url":null,"abstract":"THE POTENTIAL OF NATURAL XANTHONE α-MANGOSTIN IN THE DEVELOPMENT OF NOVEL ANTIINFECTIVE AGENTS: A REVIEW. The mangosteen (Garcinia mangostana, Linn.) is a tropical fruit cultivated in the tropical forests of Southeast Asian countries. It is recognized as the queen of fruits due to its unique color, aroma, and flavor. It has been used for centuries in Southeastern Asian traditional medicine for the treatment of various diseases. Many functional molecules with high medicinal value are obtained from the pericarp of mangosteen fruit, whose major constituent is xanthone α-mangostin. Several studies have been carried out over the last decades to further investigate and understand the pharmacological properties associated with the plant and its main chemical constituents, belonging to the class of xanthones. In addition, numerous in vitro and in vivo studies related to mangosteen have been published, indicating its importance and its potential application in medicinal chemistry. Prenylated xanthones, which include α-mangostin, are secondary metabolites particularly common in plants belonging to the Clusiaceae family. These substances have been intensively investigated for their potential as biologically active agents. This article describes a critical analysis of published data related to the properties of α-mangostin, aiming to provide a more detailed view of its potential as a chemotherapeutic agent for the prevention and treatment of infectious diseases.","PeriodicalId":49641,"journal":{"name":"Quimica Nova","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68268412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-01DOI: 10.21577/0100-4042.20170958
Jun Cai, Luyu Wang, Yunling Wu
Aniline vapor must be immediately detected at low concentrations since it is a hazardous gaseous chemical. Here, ppb level aniline vapor is detected using the metal-organic framework of UIO-66-SO3H. Utilizing a quartz crystal microbalance (QCM) sensing platform, the aniline adsorption-induced mass change of UIO-66-SO3H is converted to a signal of frequency shift. The sensor can detect a concentration of 20 ppb of aniline vapor and has good sensitivity for this purpose. Additionally, the sensor’s repeatability and stability are satisfactory. Notably, the sensor’s selectivity is prominent. Its response to aniline is much higher than that of ten interfering gases and BTEX vapor. And even in conditions with varying levels of humidity, this sensor maintains response stability.
{"title":"ROOM-TEMPERATURE PPB-LEVEL ANILINE VAPOR SENSOR FUNCTIONALIZED WITH UIO-66-SO3H","authors":"Jun Cai, Luyu Wang, Yunling Wu","doi":"10.21577/0100-4042.20170958","DOIUrl":"https://doi.org/10.21577/0100-4042.20170958","url":null,"abstract":"Aniline vapor must be immediately detected at low concentrations since it is a hazardous gaseous chemical. Here, ppb level aniline vapor is detected using the metal-organic framework of UIO-66-SO3H. Utilizing a quartz crystal microbalance (QCM) sensing platform, the aniline adsorption-induced mass change of UIO-66-SO3H is converted to a signal of frequency shift. The sensor can detect a concentration of 20 ppb of aniline vapor and has good sensitivity for this purpose. Additionally, the sensor’s repeatability and stability are satisfactory. Notably, the sensor’s selectivity is prominent. Its response to aniline is much higher than that of ten interfering gases and BTEX vapor. And even in conditions with varying levels of humidity, this sensor maintains response stability.","PeriodicalId":49641,"journal":{"name":"Quimica Nova","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68268697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-01DOI: 10.21577/0100-4042.20170960
Bruna Natali Da Costa, Camila Dantas, Beatriz Miranda, D. Lima, Olívia Maria de Oliveira, K. Garcia, Gisele Canuto, L. Teixeira
USE OF BIBLIOMETRIC ANALYSIS AS A TOOL FOR SURVEYING STUDIES ON METABOLOMICS APPLIED TO THE BIOREMEDIATION OF AREAS IMPACTED BY HYDROCARBONS. Bibliometric reviews, carried out from access to databases of scientific articles associated with software for data processing, can be helpful for qualitative and quantitative assessments of existing publications on a given topic. Several petroleum hydrocarbons are carcinogenic and immunotoxic agents, causing adverse effects on the biota, and the study of metabolites generated in bioremediation processes has been the object of current research. Therefore, in this work, the use of bibliometric analysis as a tool for surveying studies on the applied metabolomics bioremediation of areas impacted by hydrocarbons is presented. A bibliometric review was carried out in the Scopus Preview and Web of Science databases with data analysis using RStudio software with the bibliometrix package. The survey gathered the studies and prominent publications of the last seven years, making it possible to present gaps and opportunities in the area.
利用文献计量学分析作为一种工具对代谢组学进行调查研究，应用于受碳氢化合物影响地区的生物修复。利用与数据处理软件有关的科学文章数据库进行文献计量审查，有助于对某一主题的现有出版物进行定性和定量评估。几种石油碳氢化合物是致癌物和免疫毒性物质，对生物群造成不利影响，对生物修复过程中产生的代谢物的研究一直是当前研究的对象。因此，在这项工作中，使用文献计量学分析作为一种工具，对受碳氢化合物影响地区的应用代谢组学生物修复进行了调查研究。使用RStudio软件和bibliometrix软件包对Scopus Preview和Web of Science数据库进行文献计量学综述，并进行数据分析。这项调查收集了过去七年的研究和著名出版物，从而有可能提出该领域的差距和机会。
{"title":"USO DA ANÁLISE BIBLIOMÉTRICA COMO FERRAMENTA PARA O LEVANTAMENTO DE ESTUDOS SOBRE A METABOLÔMICA APLICADA NA BIORREMEDIAÇÃO DE ÁREAS IMPACTADAS POR HIDROCARBONETOS","authors":"Bruna Natali Da Costa, Camila Dantas, Beatriz Miranda, D. Lima, Olívia Maria de Oliveira, K. Garcia, Gisele Canuto, L. Teixeira","doi":"10.21577/0100-4042.20170960","DOIUrl":"https://doi.org/10.21577/0100-4042.20170960","url":null,"abstract":"USE OF BIBLIOMETRIC ANALYSIS AS A TOOL FOR SURVEYING STUDIES ON METABOLOMICS APPLIED TO THE BIOREMEDIATION OF AREAS IMPACTED BY HYDROCARBONS. Bibliometric reviews, carried out from access to databases of scientific articles associated with software for data processing, can be helpful for qualitative and quantitative assessments of existing publications on a given topic. Several petroleum hydrocarbons are carcinogenic and immunotoxic agents, causing adverse effects on the biota, and the study of metabolites generated in bioremediation processes has been the object of current research. Therefore, in this work, the use of bibliometric analysis as a tool for surveying studies on the applied metabolomics bioremediation of areas impacted by hydrocarbons is presented. A bibliometric review was carried out in the Scopus Preview and Web of Science databases with data analysis using RStudio software with the bibliometrix package. The survey gathered the studies and prominent publications of the last seven years, making it possible to present gaps and opportunities in the area.","PeriodicalId":49641,"journal":{"name":"Quimica Nova","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68268388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-01DOI: 10.21577/0100-4042.20170961
O. Lã, Caroline Sales De Azevedo, Cristina Barra, J. Netto-Ferreira, Érica de Sousa, José Rocha Jr.
The determination of total organic carbon in soils, fertilizers, sewage sludge, sediments, and humic extracts is widely performed by chemical oxidation methods with K2Cr2O7. The Yeomans-Bremner (YB) method is currently the one that stands out the most. The drawback of these methods is the large amount of concentrated H2SO4 used, which generates a large amount of hazardous waste. This work proposes using KMnO4 as an alternative to K2Cr2O7 for a lower consumption of H2SO4. The method uses the back titration of Fe2+ added to consume both the MnO2 produced and the excess KMnO4 that was not consumed in the OM oxidation. A non-trivial and yet not explored stoichiometry was applied for this purpose, providing a success not yet achieved in using permanganate to determine TOC by titration. The ideal condition for the oxidation of OC was determined by the analysis of a potassium hydrogen phthalate standard and involved the use of 0.125 mol L-1 H2SO4 and temperature of 70 °C, obtaining a significant advantage over the YB method (concentrated H2SO4 and 170 °C). The proposed method was applied to the analysis of soil samples, producing conversion factors for soil organic carbon that varied between 0.652 and 1.12.
{"title":"A GREEN AND RELIABLE TITRIMETRIC METHOD FOR TOTAL ORGANIC CARBON DETERMINATION WITH POTASSIUM PERMANGANATE","authors":"O. Lã, Caroline Sales De Azevedo, Cristina Barra, J. Netto-Ferreira, Érica de Sousa, José Rocha Jr.","doi":"10.21577/0100-4042.20170961","DOIUrl":"https://doi.org/10.21577/0100-4042.20170961","url":null,"abstract":"The determination of total organic carbon in soils, fertilizers, sewage sludge, sediments, and humic extracts is widely performed by chemical oxidation methods with K2Cr2O7. The Yeomans-Bremner (YB) method is currently the one that stands out the most. The drawback of these methods is the large amount of concentrated H2SO4 used, which generates a large amount of hazardous waste. This work proposes using KMnO4 as an alternative to K2Cr2O7 for a lower consumption of H2SO4. The method uses the back titration of Fe2+ added to consume both the MnO2 produced and the excess KMnO4 that was not consumed in the OM oxidation. A non-trivial and yet not explored stoichiometry was applied for this purpose, providing a success not yet achieved in using permanganate to determine TOC by titration. The ideal condition for the oxidation of OC was determined by the analysis of a potassium hydrogen phthalate standard and involved the use of 0.125 mol L-1 H2SO4 and temperature of 70 °C, obtaining a significant advantage over the YB method (concentrated H2SO4 and 170 °C). The proposed method was applied to the analysis of soil samples, producing conversion factors for soil organic carbon that varied between 0.652 and 1.12.","PeriodicalId":49641,"journal":{"name":"Quimica Nova","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68268856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-01DOI: 10.21577/0100-4042.20170962
Vanessa Oliveira, I. Sá, Georgtown da Silva, V. Santos, C. Araújo, A. Gonsalves
SEMICARBAZONES: INTERDISCIPLINARY APPROACH IN EXPERIMENTAL CLASSES OF ORGANIC CHEMISTRY AND MEDICINAL CHEMISTRY. Considering the chemical and pharmacological properties of semicarbazones, an interdisciplinary didactic sequence was developed to be applied in experimental classes of undergraduate courses in Pharmacy, Chemistry and related areas. This didactic sequence was planned in three steps, starting from the planning of the target molecule, a semicarbazone derived from helional, to its synthesis, physicochemical characterization (CCD, melting point, FTIR and UV-Vis) and in silico tests of its pharmacokinetic properties using the free software ADMETlab 2.0. The proposed target molecule has as molecular scaffold the 1,3-benzodiaxole nucleus and the semicarbazone function, aiming to obtain a molecule with promising anticonvulsant action and that can be obtained by a low cost and easy to execute methodology, which makes it attractive for use in experimental classes. Thus, the application of this didactic sequence aims to provide undergraduate students the opportunity to experience the process of drug development, applying techniques for planning, synthesis, characterization, and pharmacokinetic evaluation in silico. Besides reinforcing the interdisciplinary teaching of Medicinal Chemistry, applying in an integrated way the theoretical and practical knowledge of the disciplines of Organic Chemistry, Physical Chemistry, Pharmacology and Computational Chemistry.
{"title":"SEMICARBAZONAS: SEQUÊNCIA DIDÁTICA INTERDISCIPLINAR EM AULAS EXPERIMENTAIS DE QUÍMICA ORGÂNICA E QUÍMICA MEDICINAL","authors":"Vanessa Oliveira, I. Sá, Georgtown da Silva, V. Santos, C. Araújo, A. Gonsalves","doi":"10.21577/0100-4042.20170962","DOIUrl":"https://doi.org/10.21577/0100-4042.20170962","url":null,"abstract":"SEMICARBAZONES: INTERDISCIPLINARY APPROACH IN EXPERIMENTAL CLASSES OF ORGANIC CHEMISTRY AND MEDICINAL CHEMISTRY. Considering the chemical and pharmacological properties of semicarbazones, an interdisciplinary didactic sequence was developed to be applied in experimental classes of undergraduate courses in Pharmacy, Chemistry and related areas. This didactic sequence was planned in three steps, starting from the planning of the target molecule, a semicarbazone derived from helional, to its synthesis, physicochemical characterization (CCD, melting point, FTIR and UV-Vis) and in silico tests of its pharmacokinetic properties using the free software ADMETlab 2.0. The proposed target molecule has as molecular scaffold the 1,3-benzodiaxole nucleus and the semicarbazone function, aiming to obtain a molecule with promising anticonvulsant action and that can be obtained by a low cost and easy to execute methodology, which makes it attractive for use in experimental classes. Thus, the application of this didactic sequence aims to provide undergraduate students the opportunity to experience the process of drug development, applying techniques for planning, synthesis, characterization, and pharmacokinetic evaluation in silico. Besides reinforcing the interdisciplinary teaching of Medicinal Chemistry, applying in an integrated way the theoretical and practical knowledge of the disciplines of Organic Chemistry, Physical Chemistry, Pharmacology and Computational Chemistry.","PeriodicalId":49641,"journal":{"name":"Quimica Nova","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68268877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-01DOI: 10.21577/0100-4042.20170955
Josefredo Pliego Jr.
SCIENTISTS’ ASSESSMENT: ARE WE USING THE CORRECT METRICS? The use of metrics to evaluate scientists is widespread in the present time, with implications for hiring, fellowships, and research grants. Such fact requires that metrics must be constantly scrutinized to be improved. This work analyzes the use of metrics in the area of chemistry in Brazil and discusses its limitations and shortcomings. The main findings indicate that the use of the impact factor must be complemented by the cited half-life of the journals, and a composite metric named influence factor is proposed, similar to the R-impact. The h-index is not a good metric anymore because does not correct for authorship inflation. The individual h-index (hi), which takes into account fractional counting of citations, is more reliable than the h-index. An analysis on the use of hi-index with randomly selected 15 Brazilian chemists among the top 500 more productive shows an important effect on the ranking order.
{"title":"AVALIAÇÃO DOS CIENTISTAS: UTILIZAMOS AS MÉTRICAS CORRETAS?","authors":"Josefredo Pliego Jr.","doi":"10.21577/0100-4042.20170955","DOIUrl":"https://doi.org/10.21577/0100-4042.20170955","url":null,"abstract":"SCIENTISTS’ ASSESSMENT: ARE WE USING THE CORRECT METRICS? The use of metrics to evaluate scientists is widespread in the present time, with implications for hiring, fellowships, and research grants. Such fact requires that metrics must be constantly scrutinized to be improved. This work analyzes the use of metrics in the area of chemistry in Brazil and discusses its limitations and shortcomings. The main findings indicate that the use of the impact factor must be complemented by the cited half-life of the journals, and a composite metric named influence factor is proposed, similar to the R-impact. The h-index is not a good metric anymore because does not correct for authorship inflation. The individual h-index (hi), which takes into account fractional counting of citations, is more reliable than the h-index. An analysis on the use of hi-index with randomly selected 15 Brazilian chemists among the top 500 more productive shows an important effect on the ranking order.","PeriodicalId":49641,"journal":{"name":"Quimica Nova","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68268427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-01DOI: 10.21577/0100-4042.20170963
Carlos Rodrigues, Edemar Kirchhof, J. Rocco
DETERMINATION OF DEGRADATION KINETIC PARAMETERS AND FAILURE TIME ESTIMATION OF MAGNESIUM TEFLON® VITON® ELECTRONIC “FLARE” COUNTERMEASURES. Flare type countermeasures that use the composition designated as MTV (Magnesium, Teflon®, Viton®), are the most used by Air Forces around the world. In Brazil, these “flares” are used in several locations and are subjected to different handling, storage and operation conditions that can affect their performance and compromise their service life. In this work, the Monte Carlo method was applied to estimate an empirical model to predict the lifetime of these countermeasures, using as variables the temperature and the relative humidity of the place where the material is used. The results were analyzed using multiple linear regression and analysis of variance. The kinetic parameters of material thermal degradation, such as Activation Energy and Pre-exponential Factor, and the estimated failure times of these countermeasures were determined. The results pointed out to strong temperature influence on material degradation resulting in different lifetimes for each site studied.
{"title":"DETERMINAÇÃO DOS PARÂMETROS CINÉTICOS DE DEGRADAÇÃO E ESTIMATIVA DO TEMPO DE FALHA DE CONTRAMEDIDAS ELETRÔNICAS “FLARE” DO TIPO MAGNÉSIO TEFLON® VITON®","authors":"Carlos Rodrigues, Edemar Kirchhof, J. Rocco","doi":"10.21577/0100-4042.20170963","DOIUrl":"https://doi.org/10.21577/0100-4042.20170963","url":null,"abstract":"DETERMINATION OF DEGRADATION KINETIC PARAMETERS AND FAILURE TIME ESTIMATION OF MAGNESIUM TEFLON® VITON® ELECTRONIC “FLARE” COUNTERMEASURES. Flare type countermeasures that use the composition designated as MTV (Magnesium, Teflon®, Viton®), are the most used by Air Forces around the world. In Brazil, these “flares” are used in several locations and are subjected to different handling, storage and operation conditions that can affect their performance and compromise their service life. In this work, the Monte Carlo method was applied to estimate an empirical model to predict the lifetime of these countermeasures, using as variables the temperature and the relative humidity of the place where the material is used. The results were analyzed using multiple linear regression and analysis of variance. The kinetic parameters of material thermal degradation, such as Activation Energy and Pre-exponential Factor, and the estimated failure times of these countermeasures were determined. The results pointed out to strong temperature influence on material degradation resulting in different lifetimes for each site studied.","PeriodicalId":49641,"journal":{"name":"Quimica Nova","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68268937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-01DOI: 10.21577/0100-4042.20230004
Vinícius Pinto, Gerlon Oliveira, Christian Gomides, M. Monteiro, L. Lião
STUDY OF PREMIUM AND REGULAR GASOLINES MARKETED IN BRAZIL THROUGH THE ERETIC-NMR METHOD AND CHEMOMETRICS. Gasoline is a complex mixture of hydrocarbons whose detailed study of its chemical profiles is a challenging task. This type of product of great commercial importance has its quality measured in Brazil from classical physicalchemical tests. Although robust, physical-chemical analyses generally require large amounts of assays, solvents, and samples, in addition to not being indicated for the detection of small compositional changes. In this work, NMR and chemometrics were used in the quantitative study of different samples of gasoline with varying ratings of octane and ethanol contents. The results demonstrated the usefulness of NMR spectroscopy both to characterize as well as to distinguish the chemical profiles of regular and premium gasoline. With the application of the ERETIC, the chemical profiles mentioned were quantitatively differentiated and the proportions between hydrocarbons were determined for both types of gasoline. The application of the ERETIC was also successful in the quantitative determination of ethanol contents in regular and premium gasoline. The aforementioned method, which dispenses with the use of quantification standards inserted directly into the sample of interest, was unequivocal in accounting for the volume of ethanol, in addition to showing excellent agreement with the method currently adopted by the Brazilian government.
{"title":"ESTUDO DE GASOLINAS PREMIUM E COMUM COMERCIALIZADAS NO BRASIL ATRAVÉS DO MÉTODO ERETIC-RMN E QUIMIOMETRIA","authors":"Vinícius Pinto, Gerlon Oliveira, Christian Gomides, M. Monteiro, L. Lião","doi":"10.21577/0100-4042.20230004","DOIUrl":"https://doi.org/10.21577/0100-4042.20230004","url":null,"abstract":"STUDY OF PREMIUM AND REGULAR GASOLINES MARKETED IN BRAZIL THROUGH THE ERETIC-NMR METHOD AND CHEMOMETRICS. Gasoline is a complex mixture of hydrocarbons whose detailed study of its chemical profiles is a challenging task. This type of product of great commercial importance has its quality measured in Brazil from classical physicalchemical tests. Although robust, physical-chemical analyses generally require large amounts of assays, solvents, and samples, in addition to not being indicated for the detection of small compositional changes. In this work, NMR and chemometrics were used in the quantitative study of different samples of gasoline with varying ratings of octane and ethanol contents. The results demonstrated the usefulness of NMR spectroscopy both to characterize as well as to distinguish the chemical profiles of regular and premium gasoline. With the application of the ERETIC, the chemical profiles mentioned were quantitatively differentiated and the proportions between hydrocarbons were determined for both types of gasoline. The application of the ERETIC was also successful in the quantitative determination of ethanol contents in regular and premium gasoline. The aforementioned method, which dispenses with the use of quantification standards inserted directly into the sample of interest, was unequivocal in accounting for the volume of ethanol, in addition to showing excellent agreement with the method currently adopted by the Brazilian government.","PeriodicalId":49641,"journal":{"name":"Quimica Nova","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68269924","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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