Aplicação de análise de componentes principais para verificação de atribuições de sinais nos espetros de RMN ¹H: o caso dos 3-aril (1,2,4)-oxadiazol-5-carboidrazida benzilidenos

Silva, João Bosco P. da; Malvestiti, Ivani; Hallwass, Fernando; Ramos, Mozart N.; Leite, Luiz Arthur Calheiros; Barreiro, Eliezer J.

doi:10.1590/s0100-40422005000300022

Cited by 5 publications

(4 citation statements)

References 3 publications

(3 reference statements)

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“…Principal component analysis (PCA) is a mathematical method of reorganizing information from data sets. It is used in many branch of science, such as biology and public health [9], chemistry [10], physics [11] and materials science [12]. In brief, what PCA does is to discover new variables, termed principal components (PCs), which account for the majority of the variability in the data.…”

Section: Briefing On the Principal Component Analysis Theorymentioning

confidence: 99%

Viscosity of strong and fragile glass-forming liquids investigated by means of principal component analysis

Nascimento

Aparicio

2007

Journal of Physics and Chemistry of Solids

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The Vogel-Fulcher-Tammann-Hesse (VFTH) equation has been the most widespread tool for describing the temperature dependence with viscosity for strong, moderate and fragile glass-forming liquids. In this work, the VFTH equation was applied over a wide temperature range (between the glass transition temperature, T g , and the melting point, T m ) for 38 oxide glasses, considering simple, binary and ternary compositions of silicate and borate systems. The Levenberg-Marquart non-linear fitting procedure was used to assess VFTH viscosity parameters B and T 0 , maintaining A ¼ À5 fixed (in Pa Á s) to reduce the number of adjustable parameters. Regarding this restriction, the VFTH formula has shown to adjust very well to experimental data in a wide temperature range. Previous assertions revealed that there is statistical correlation between B and T 0 . Principal component analysis (PCA) was used in the present study to verify the correlation between the B and T 0 parameters [J. F. Mano, E. Pereira, J. Phys. Chem. A 108 ( 2004) 10824], as well as between T g and T m . In brief, PCA is a mathematical method aimed at reorganizing information from data sets. The results have shown that it is possible to map either borate (and almost fragile) or silicate (usually strong up to near fragile) systems. As a statistical tool, PCA justifies the use of B, T 0 and T g as the main parameters for the fragility indexes m ¼ dðlog 10 ZÞ dðT g =TÞ T¼Tg and D ¼ B/T 0 , where Z is the viscosity and T the absolute temperature.

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Section: Briefing On the Principal Component Analysis Theorymentioning

confidence: 99%

Viscosity of strong and fragile glass-forming liquids investigated by means of principal component analysis

Nascimento

Aparicio

2007

Journal of Physics and Chemistry of Solids

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“…Essa análise será realizada por meio da técnica de análise de componentes principais, conforme estabelecem Mardia, Kent e Bibby (1979). Essa técnica já tem sido empregada com sucesso (RAMOS et al, 2005) e (SILVA; RAMOS, 2012) em diversos problemas que exigiram uma análise estatística de dados multivariados, permitindo construir gráficos bidimensionais a partir de matrizes multidimensionais.…”

Section: Introductionunclassified

Uma análise estatística multivariada do desempenho das escolas municipais de Ribeirão Preto ,

Ramos

Filho

Silva

et al. 2021

Ensaio: aval.pol.públ.Educ.

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Resumo Esse estudo faz uma análise estatística multivariada de componentes principais (ACP) para estabelecer padrões de desempenho escolar para o 5° e o 9° ano do Ensino Fundamental das escolas municipais de Ribeirão Preto. As equações matemáticas obtidas de gráficos bidimensionais de ACP revelam que os percentuais de alunos com aprendizado adequado em língua portuguesa e em matemática são os indicadores mais significativos para explicar tais padrões de desempenho. A partir dessa análise, foi possível estabelecer vetores de desempenho escolar para cada uma das escolas dos dois anos escolares do Ensino Fundamental aqui considerados. Isso permitiu construir um indicador de heterogeneidade para as escolas da rede municipal de Educação de Ribeirão Preto.

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“…The application of PCA to spectroscopy in general and to NMR spectroscop y in particular , has increased recently with the aim of providing valuable graphica l representation s for the analysis of multivari ate data [18][19][20][21]. PCA is a mathematical method for reducing the dimensional ity of a data set consisting of a large number of interrelated variables.…”

Section: Introductionmentioning

confidence: 99%

Determination of the position of the N-O function in substituted pyrazine N-oxides by chemometric analysis of carbon-13 nuclear magnetic resonance data

Butler

Cabrera

2013

Journal of Molecular Structure

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Aplicação de análise de componentes principais para verificação de atribuições de sinais nos espetros de RMN ¹H: o caso dos 3-aril (1,2,4)-oxadiazol-5-carboidrazida benzilidenos

Cited by 5 publications

References 3 publications

Viscosity of strong and fragile glass-forming liquids investigated by means of principal component analysis

Viscosity of strong and fragile glass-forming liquids investigated by means of principal component analysis

Uma análise estatística multivariada do desempenho das escolas municipais de Ribeirão Preto ,

Determination of the position of the N-O function in substituted pyrazine N-oxides by chemometric analysis of carbon-13 nuclear magnetic resonance data

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