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Your search keyword '"FERREIRA, MÁRCIA M. C."' showing total 141 results
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141 results on '"FERREIRA, MÁRCIA M. C."'

1. Synthesis of vanillin derivatives with 1,2,3‐triazole fragments and evaluation of their fungicide and fungistatic activities

Author

Gazolla, Poliana A. R., primary, de Aguiar, Alex R., additional, Costa, Maria C. A., additional, Oliveira, Osmair V., additional, Costa, Adilson V., additional, da Silva, Cleiton M., additional, do Nascimento, Claudia J., additional, Junker, Jochen, additional, Ferreira, Rafaela S., additional, de Oliveira, Fabrício M., additional, Vaz, Boniek G., additional, do Carmo, Paulo H. F., additional, Santos, Daniel A., additional, Ferreira, Márcia M. C., additional, and Teixeira, Róbson R., additional

Published
2023
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3. Estudo do coeficiente de partição octanol-água de bifenilas policloradas (PCBs) utilizando parâmetros topológicos

Author

Silva Lucicleide Ribeiro da and Ferreira Márcia M. C.

Subjects
topological indices, chemometrics, QSPR, Chemistry, QD1-999
Abstract

A model based on chemical structure was developed for the accurate prediction of octanol/water partition coefficient (K OW) of polychlorinated biphenyls (PCBs), which are molecules of environmental interest. Partial least squares (PLS) was used to build the regression model. Topological indices were used as molecular descriptors. Variable selection was performed by Hierarchical Cluster Analysis (HCA). In the modeling process, the experimental K OW measured for 30 PCBs by thin-layer chromatography - retention time (TLC-RT) has been used. The developed model (Q² = 0,990 and r² = 0,994) was used to estimate the log K OW values for the 179 PCB congeners whose K OW data have not yet been measured by TLC-RT method. The results showed that topological indices can be very useful to predict the K OW.

Published
2003

4. Clustering of comb and propolis waxes based on the distribution of aliphatic constituents

Author

Custodio Angela R., Ferreira Márcia M. C., Negri Giuseppina, and Salatino Antonio

Subjects
propolis wax, comb wax, hydrocarbons, wax esters, Hierarchic Cluster Analysis, Chemistry, QD1-999
Abstract

Chemical composition data for 41 samples of propolis waxes and 9 samples of comb waxes of Apis mellifera collected mainly in Brazil were treated using Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA). For chemometrical analysis, the distribution of hydrocarbons and residues of alcohols and carboxylic acids of monoesters were considered. The clustering obtained revealed chemical affinities and differences not previously grasped by simple eye-inspection of the data. No consistent differences were detected between comb and propolis waxes. These and previous results suggest that hydrocarbons, carboxylic acids, aliphatic alcohols and esters from both comb and propolis waxes are bee-produced compounds and, hence, the differences detected between one and another region are dependent on genetic factors related to the insects rather than the local flora. The samples analyzed were split into two main clusters, one of them comprising exclusively material collected in the State of São Paulo. The results are discussed with respect to the africanization of honeybees that first took place in that State and therefrom irradiated to other parts of Brazil.

Published
2003

5. Molecular graphics-structural and molecular graphics descriptors in a QSAR study of 17-a-acetoxyprogesterones

Author

Kiralj Rudolf and Ferreira Márcia M. C.

Subjects
progesterone derivatives, partial least squares, molecular graphics descriptors, molecular graphics-structural descriptors, Chemistry, QD1-999
Abstract

Quantitative Structure-Activity Relationship study on 21 oral progestogens, 19 of which are 17-alpha-acetoxyprogesterones, was performed by using Partial Least Squares. Fairly good regression models were achieved, the best being Q²=0.707, R²=0.811 with two Principal Components and four descriptors. Most of the molecular descriptors were generated from molecular graphics of DFT 6-31G** optimized geometries (molecular graphics descriptors) or were additionally combined with experimental structural parameters of progesterone receptor - progesterone complex (molecular graphics-structural, or molecular graphics and modeling descriptors). Regression models employing only these molecular graphics-based descriptors reached Q²=0.556, R²=0.718 with three Principal Components and five descriptors, demonstrating their usefulness in QSAR studies. In the case of progesterone derivatives, molecular graphics descriptors successfully included various conformational, steric and electronic substituent effects.

Published
2003

6. Multivariate QSAR

Author

Ferreira Márcia M. C.

Subjects
chemometrics, principal component analysis, partial least squares, SIMCA, KNN, Chemistry, QD1-999
Abstract

In this work, the chemometric techniques most frequently used in QSAR (quantitative structure-activity relationships) studies are reviewed. They are introduced in chronological order, beginning with Hansch analysis and the exploratory data analysis methods of principal components and hierarchical clustering (PCA and HCA). Principal component regression and partial least squares regression methods (PCR and PLS) are discussed, followed by the pattern recognition methods (KNN and SIMCA). Different applications are presented to illustrate these chemometric techniques. The methodology used for regression in 3D-QSAR is presented (unfolding PLS). Finally, the higher order method called Multilinear PLS, already used in analytical chemistry but not yet explored by the QSAR community, is introduced. This method maintains the multiway structure of the data and has several advantages over bilinear PLS including speed in calculation, simplicity and stability, since the number of parameters to be estimated can be greatly reduced.

Published
2002

11. Multitrophic interactions in the rhizosphere microbiome of wheat: from bacteria and fungi to protists

Author

Rossmann, Maike, primary, Pérez-Jaramillo, Juan E, primary, Kavamura, Vanessa N, primary, Chiaramonte, Josiane B, primary, Dumack, Kenneth, primary, Fiore-Donno, Anna Maria, primary, Mendes, Lucas W, primary, Ferreira, Márcia M C, primary, Bonkowski, Michael, primary, Raaijmakers, Jos M, primary, Mauchline, Tim H, primary, and Mendes, Rodrigo, primary

Published
2020
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15. Determination of Cellulose Crystallinity of Banana Residues Using Near Infrared Spectroscopy and Multivariate Analysis

Author

Rambo,Magale K. D. and Ferreira,Márcia M. C.

Subjects
near infrared spectroscopy, sense organs, chemometrics, crystallinity, lignocellulosic biomass, X-ray diffraction
Abstract

Crystallinity is an important property of lignocellulosic biomass due to its significant effect on acid/enzymatic hydrolysis. Normally, physicochemical analysis, such as powder X-ray diffraction and nuclear magnetic resonance, is used to reveal the crystallinity content. However, these analytical methods are expensive and laborious. In this context, methods that rapidly predict the crystallinity are important, even if used only for screening calibration. Thus, we intend to show the potential of near-infrared spectroscopy (NIRS) and chemometrics to replace reference methods in crystallinity determination. The results show that NIRS can be used to determine crystallinity in banana residues by the use of partial least squares regression, providing good coefficients of determination (R2cal,pred > 0.82), low relative errors (< 14%) and good range error ratio (≥ 7.7). The interpretation of the regression coefficients, multivariate figures of merit and external validation results indicate a strong relationship between the NIR spectrum and crystallinity in banana samples.

Published
2015

17. Reconhecimento de padrões por métodos não supervisionados: explorando procedimentos quimiométricos para tratamento de dados analíticos

Author

Correia, Paulo R. M. and Ferreira, Márcia M. C.

Subjects
analytical chemistry, pattern recognition, chemometrics
Abstract

An activity for introducing hierarchical cluster analysis (HCA) and principal component analysis (PCA) during the Instrumental Analytical Chemistry course is presented. The posed problem involves the discrimination of mineral water samples according to their geographical origin. Thirty-seven samples of 9 different brands were considered and the results from the determination of Na, K, Mg, Ca, Sr and Ba were taken into account. Non-supervised methods for pattern recognition were explored to construct a dendrogram, score and loading plots. The devised activity can be adopted for introducing Chemometrics devoted to data handling, stressing its importance in the context of modern Analytical Chemistry.

Published
2007

19. Estudo do coeficiente de partição octanol-água de bifenilas policloradas (PCBs) utilizando parâmetros topológicos

Author

Silva, Lucicleide Ribeiro da and Ferreira, Márcia M. C.

Subjects
QSPR, topological indices, chemometrics
Abstract

A model based on chemical structure was developed for the accurate prediction of octanol/water partition coefficient (K OW) of polychlorinated biphenyls (PCBs), which are molecules of environmental interest. Partial least squares (PLS) was used to build the regression model. Topological indices were used as molecular descriptors. Variable selection was performed by Hierarchical Cluster Analysis (HCA). In the modeling process, the experimental K OW measured for 30 PCBs by thin-layer chromatography - retention time (TLC-RT) has been used. The developed model (Q² = 0,990 and r² = 0,994) was used to estimate the log K OW values for the 179 PCB congeners whose K OW data have not yet been measured by TLC-RT method. The results showed that topological indices can be very useful to predict the K OW.

Published
2003

20. Separação de espectros simulados e de luminescência total através do método generalizado de anulação do posto (GRAM)

Author

Reis, Marlon Martins dos and Ferreira, Márcia M. C.

Subjects
Generalized Rank Annihilation Method, curve resolution, chemometrics
Abstract

A multivariate curve resolution method, "GENERALIZED RANK ANNIHILATION METHOD (GRAM)", is discussed and tested with simulated and experimental data. The analysis of simulated data provides general guidelines concerning the condition for uniqueness of a solution for a given problem. The second-order emission-excitation spectra of human and animal dental calculus deposits were used as an experimental data to estimate the performance of the above method. Three porphyrinic spectral profiles, for both human and cat, were obtained by the use of GRAM.

Published
1999

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