Article
Energy & Fuels
Sherif S. M. Ghoneim
Summary: The aging of power transformers can cause various defects and damages in the insulating system, particularly in the insulating paper. Statistical tools can be used to establish a connection between the DP and testing parameters of transformer samples to determine the status of the insulating paper and the remaining life percentage.
Article
Automation & Control Systems
Yun Liu, Tom Fearn, Matija Strlic
Summary: This paper explores the development of a NIR spectroscopic method combined with multivariate analysis for characterising historical paper, focusing on predicting the degree of polymerisation (DP) using PLS regression. The study found that variance of predicted DP by the NIR-PLS models contributed the most to the total error of prediction, highlighting the importance of improving instrumentation and operational procedures to enhance model performance. Additionally, the model for historical paper was shown to be robust to variations in relative humidity, indicating its applicability for collection surveys in different environments.
CHEMOMETRICS AND INTELLIGENT LABORATORY SYSTEMS
(2021)
Article
Automation & Control Systems
Lakshmi Alagappan, Jia En Chu, Joanna Huixin Chua, Jia Wen Ding, Ronghui Xiao, Zhe Yu, Kun Pan, Untzizu Elejalde, Kevin Junliang Lim, Limsoon Wong
Summary: In this study, a new classification and correction technique called CSCAC is proposed, which can simultaneously correct batch effects, perform multi-class classification, and detect new classes. The effectiveness of the method is demonstrated through classification experiments on different types of oils.
CHEMOMETRICS AND INTELLIGENT LABORATORY SYSTEMS
(2023)
Article
Engineering, Chemical
Sherif S. M. Ghoneim
Summary: The continuity of transformer operation is crucial for maintaining power flow and revenue for utilities. Transformer failures are mainly due to the degradation of the insulating system, with DP being a key detector of insulating paper state. This research constructed a prediction model using regular tests on transformer insulating oil as predictors, and classified the DP into five classes to express the insulating paper aging rate, with decision tree proving to be the most accurate classifier with a 96.2% prediction accuracy.
Article
Spectroscopy
Nana Adwoa Nkuma Johnson, Selorm Yao-Say Solomon Adade, Suleiman A. Haruna, John-Nelson Ekumah, Yongkun Ma
Summary: This study investigated the prospects of using near-infrared (NIR) spectroscopy and effective variable selection algorithms for quantifying phytochemical compounds in chickpea beverages. The competitive adaptive reweighted sampling-partial least squares (CARS-PLS) model showed superior performance in predicting biochanin A, chlorogenic acid, pcoumaric acid, and stigmasterol.
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
(2024)
Article
Materials Science, Composites
Xing Li, Bowen Zhang, Zhiyu Wu, Yuemei Liu, Jun Hu, Chunhua Zhang, Genyang Cao, Ke Zhang, Jiuxiao Sun, Xin Liu, Weilin Xu
Summary: A polyimide (PI) fiber with a dense three-dimensional network structure was obtained by planar centrifugation using poly(amic acid) (PAA) as a source solution. A PI composite paper was formed by sandwiching the PI fiber paper between two PI films. The PI fiber paper showed good mechanical properties, high thermal stability, low dielectric constant, and high breakdown strength. The PI composite paper had a breakdown strength much better than commercial organic electrical insulating paper, and the production of large scaled PI fiber paper and PI composite paper could be achieved continuously and environmentally.
COMPOSITES COMMUNICATIONS
(2023)
Article
Materials Science, Paper & Wood
Enze Zhang, Hanbo Zheng, Chuansheng Zhang, Jiaqi Wang, Kuikui Shi, Jing Guo, Harald Schwarz, Chaohai Zhang
Summary: The study introduced a non-destructive method based on multivariate chemical indicators to improve the reliability and accuracy of transformer cellulose paper insulation assessment, which was validated by experiments.
Review
Engineering, Electrical & Electronic
Haoxi Cong, Hao Pan, Danyang Qian, Haiyu Zhao, Qingmin Li
Summary: This article provides a comprehensive summary on the field of sulphur corrosion of oil-paper insulation in mineral oil transformers, covering the corrosion mechanisms, factors influencing corrosion reactions, characterisation methods, protection technologies, and operational measures. It also highlights four key issues that need further exploration: the synergistic deterioration mechanism of sulphide, the micro-process and forming path of sulphur corrosion reaction, characteristic parameters and quantitative characterisation methods of sulphur corrosion degree, and effective protection technologies. Efforts will be made to deepen understanding of the sulphur corrosion phenomenon and its deterioration mechanisms in order to propose solid theoretical basis and feasible technical means for preventing sulphur corrosion insulation failure.
Article
Biochemistry & Molecular Biology
Tibor Casian, Alexandru Gavan, Sonia Iurian, Alina Porfire, Valentin Toma, Rares Stiufiuc, Ioan Tomuta
Summary: The study evaluated the performance of a portable NIR spectrometer in a pharmaceutical powder blend application, showing accurate prediction of content uniformity but lower performance compared to a benchtop spectrometer. Spectral variability induced by dynamic acquisition was efficiently managed through spectral pre-processing.
Review
Engineering, Electrical & Electronic
Qingguo Chen, Wei Sun, Song Cheng, Guokai Huang
Summary: Insulation paper plays a crucial role in evaluating the insulation status of transformers. The traditional evaluation methods, such as dissolved gas component content analysis and furfural content analysis, have limitations in accuracy and field application. Recent research has explored methanol as a novel marker for aging evaluation of transformer insulating paper, which has shown better correlation with insulation aging state. This paper summarizes the current research status, detection methods, and development prospects of methanol in insulating oil, with the aim of providing reference for aging evaluation of oil immersed power transformer.
IET GENERATION TRANSMISSION & DISTRIBUTION
(2023)
Article
Agronomy
Audrey Pissard, Emanuel Jose Nascimento Marques, Pierre Dardenne, Marc Lateur, Celio Pasquini, Maria Fernanda Pimentel, Juan Antonio Fernandez Pierna, Vincent Baeten
Summary: The study compared the analytical performance of benchtop and portable spectrometers for evaluating quality parameters of apples and found that they offered similar performance. Calibration transfer between devices using LS-SVM method showed significant improvement in prediction accuracy with only a few transfer samples needed.
POSTHARVEST BIOLOGY AND TECHNOLOGY
(2021)
Article
Chemistry, Analytical
Mayara F. Barbosa, Jainny R. B. Santos, Alexandre N. Silva, Sofacles F. C. Soares, Mario C. U. Araujo
Summary: A new NIR detection system was developed for automatic quantification of methane, ethane, and propane in natural gas and biogas samples. High correlation coefficients were achieved using PLS models constructed from raw and second-derivative NIR spectra, with the advantage of eliminating preprocessing steps for future sample prediction.
MICROCHEMICAL JOURNAL
(2021)
Article
Chemistry, Analytical
Robert C. Spiers, Callan Norby, John H. Kalivas
Summary: Determining sample similarity is crucial in analytical chemistry, but quantifying it is a challenge. This paper introduces PRISM, a hybrid method that integrates spectral similarity information with contextual considerations to evaluate sample similarity. PRISM is tested on NIR data sets for various applications and shows effectiveness in collecting and integrating similarity information to produce quantitative evaluations.
ANALYTICAL CHEMISTRY
(2023)
Article
Spectroscopy
Suleiman A. Haruna, Huanhuan Li, Muhammad Zareef, Md Mehedi Hassan, Muhammad Arslan, Wenhui Geng, Wenya Wei, Munir Abba Dandago, Selorm Yao-Say Solomon Adade, Quansheng Chen
Summary: This study investigated two key parameters for evaluating the oxidation level in crude peanut oil. The combination of near-infrared spectroscopy and chemometric algorithms was attempted and assessed. The results showed that near-infrared spectroscopy coupled with CARS-PLS could be used as a fast and non-invasive technique for quantifying acid value and peroxide value in crude peanut oil.
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
(2022)
Article
Energy & Fuels
Ahmed Sayadi, Djillali Mahi, Issouf Fofana, Lakhdar Bessissa, Sid Ahmed Bessedik, Oscar Henry Arroyo-Fernandez, Jocelyn Jalbert
Summary: The aim of this research is to predict the mechanical properties and behaviors of insulation paper used in power transformers under thermal aging. An artificial neural network model trained with a multiple regression model and a particle swarm optimization model is applied. The aging of the paper insulation is monitored directly and indirectly using chemical markers. A mathematical model is developed to simulate the mechanical properties of the aged insulation paper. The proposed model shows accurate results when compared to experimental data.
Article
Biochemical Research Methods
Levi Oliveira, Manuel Arroyave, Marcelo F. Pistonesi, Wallace Fragoso, Valeria Springer
Summary: In this study, quantification of mixed nanoparticles, including carbon dots and silver nanoparticles, was successfully achieved using CE-DAD analysis method and chemometric models. This provides an effective solution for research applications and regulatory purposes of mixed nanoparticles. The method is efficient, accurate, and does not require sample purification.
Article
Chemistry, Applied
Bruno Henrique da Silva Melo, Rafaella Figueiredo Sales, Lourival da Silva Bastos Filho, Jorge Souza Povoas da Silva, Aluska Gabrielle Carolino de Almeida Sousa, Deborah Maria Camara Peixoto, Maria Fernanda Pimentel
Summary: This study evaluated a handheld NIR spectrometer for developing calibration models to quantify brix and pol in an industrial sugar production process. Results showed that SVR performed the best in handling non-linear relationships within the data, leading to more accurate predictions of brix and pol content.
Article
Spectroscopy
Aline C. S. Fonseca, Jose F. Q. Pereira, Ricardo S. Honorato, Rasmus Bro, Maria Fernanda Pimentel
Summary: This study evaluated the potential of identifying human blood in stains deposited on different types of floor tiles using a portable NIR instrument, achieving high sensitivity and specificity results. Hierarchical models combining multivariate analysis techniques successfully identified traces of human blood, animal blood, and common false positives, demonstrating significant advances in the methodology for identifying human blood stains at crime scenes.
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
(2022)
Article
Chemistry, Analytical
Flavio M. de Andrade, Rafaella Sales, Neirivaldo C. da Silva, Maria Fernanda Pimentel
Summary: This study presents a novel multivariate calibration method using virtual standards for the on-line monitoring of alkyl-esters content during biodiesel production. By mathematically mixing spectra from pure components and performing an adjustment, the need for calibration samples is greatly reduced, resulting in similar predictive results compared to conventional methods.
Article
Food Science & Technology
Ivo Diego de Lima Silva, Jose Augusto de Almeida Nascimento, Luiz Emilio Pessoa Timeni de Moraes Filho, Viviane Fonseca Caetano, Michelle Felix de Andrade, Yeda Medeiros Bastos de Almeida, Fernando Hallwass, Andrea Monteiro Santana Silva Brito, Gloria Maria Vinhas
Summary: This study developed poly(vinyl alcohol) films incorporated with cashew tree extract, which showed potential antimicrobial and antioxidant applications. The films exhibited promising values for antioxidant and antimicrobial activities, making them suitable for active packaging.
JOURNAL OF FOOD PROCESSING AND PRESERVATION
(2022)
Article
Horticulture
Fred Augusto Louredo de Brito, Yara Panta de Araujo, Ariel Sharon de Araujo Nogueira Marcelino, Natanael Lucena Ferreira, Kelem Silva Fonseca, Andrea Monteiro Santana Silva Brito, Thieres George Freire da Silva, Adriano do Nascimento Simoes
Summary: This study aims to evaluate the production and properties of films made from different species of Nopalea and Opuntia clones. The research found that Nopalea has the potential to produce biodegradable films, similar to Opuntia.
JOURNAL OF THE PROFESSIONAL ASSOCIATION FOR CACTUS DEVELOPMENT
(2022)
Article
Biotechnology & Applied Microbiology
Gabriel O. Locatelli, Maria Fernanda Pimentel, Luciano A. Bueno, Murillo Lobo, Gabriel M. Mascarin, Christine L. Luna Finkler
Summary: The aim of this study was to optimize the nutritional conditions for microsclerotia (MS) production using low-cost carbon and nitrogen sources for two strains of Trichoderma asperellum from Brazil. The results showed that the optimal conditions for BRM-29104 strain were sucrose and autolyzed yeast as carbon sources, carbon concentration of 20 g L-1, and C:N ratio of 10:1, which resulted in high MS yield. Vacuum filtration using a nylon filter increased the concentration of MS.
BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY
(2022)
Article
Automation & Control Systems
Luan Cassio Barbosa-Patricio, Rafaella de F. Sales, Neirivaldo C. da Silva, Maria Eduarda Fernandes da Silva, Livia Rodrigues e Brito, Maria Fernanda Pimentel
Summary: This study proposes a method based on the physicochemical properties of gasoline to quickly compare gasoline samples. By developing a computational approach to generate virtual samples and considering the uncertainties of measurement methods, the need for repeated measurements can be reduced. The results show that the proposed method has a high discriminability for gasoline comparison.
CHEMOMETRICS AND INTELLIGENT LABORATORY SYSTEMS
(2022)
Article
Chemistry, Applied
Jose Marcelino Netto, Fernanda A. Honorato, Paulo Gustavo Celso, Maria Fernanda Pimentel
Summary: This study developed a method based on near infrared spectroscopy to identify adulterated almond flour. The results showed that portable NIR instruments are highly efficient for the identification and quantification of adulterated almond flour.
JOURNAL OF FOOD COMPOSITION AND ANALYSIS
(2023)
Article
Chemistry, Multidisciplinary
Maria J. da Silva, Ana Paula S. Paim, Iago J. S. da Silva, Maria Fernanda Pimentel, Maria Luisa Cervera, Miguel de la Guardia
Summary: This study determined the levels of total mercury in various food samples consumed by people of different ages in Spain and evaluated the potential toxicological risks. The results showed that if tuna is excluded from the menu, the daily intake of total mercury does not pose risks to Spanish children and adults.
JOURNAL OF THE BRAZILIAN CHEMICAL SOCIETY
(2022)
Article
Environmental Sciences
Jacqueline Santos Silva-Cavalcanti, Jayne Crisleny Pereira Silva, Flavio Montenegro de Andrade, Andrea Monteiro Santana Silva Brito, Monica Ferreira da Costa
Summary: This study assessed microplastic pollution in tropical shallow lakes and found different types and colors of microplastics in lake sediments. The results showed that environmental factors influenced the concentration of microplastics, but there was only a small difference between different regions. The study also suggested that pollution from sanitation, sewage effluents, and solid waste may be the main factors contributing to microplastic contamination.
SCIENCE OF THE TOTAL ENVIRONMENT
(2023)
Article
Chemistry, Analytical
Alcides Silva Siqueira, Luciano Farias Almeida, Wallace Duarte Fragoso
Summary: A fast and sensitive strategy was developed to quantify polycyclic aromatic hydrocarbons (PAHs) in tap water and sediment samples. The method employed solid-phase extraction on a nylon membrane using a lab-made propulsion system and measured fluorescent signals on the non-pressurized membrane surface. Parallel factor analysis (PARAFAC) was used to resolve spectral overlapping and model matrix interferences. The study results demonstrated that the proposed method can successfully quantify PAHs in real samples.
Article
Chemistry, Analytical
Denilson Mendes de Oliveira, Celio Pasquini, Ana Rita de Araujo Nogueira, Marcio Dias Rabelo, Maria Lucia Ferreira Simeone, Gilberto Batista de Souza
Summary: This study compared the performance of a compact and a benchtop spectrometer in measuring six nutritional traits of Brachiaria forages. The results showed that, despite its lower analytical sensitivity, the compact instrument performed well compared to the benchtop instrument in routine measurements.
MICROCHEMICAL JOURNAL
(2024)
Article
Chemistry, Analytical
Aline C. S. Fonseca, Jose F. Q. Pereira, Ricardo S. Honorato, Rasmus Bro, Maria Fernanda Pimentel
Summary: This study aims to enhance the performance of hierarchical models in identifying bloodstains deposited at different times. The best results were achieved by adding fresher samples to the training set and using partial least squares-discriminant analysis as the second decision rule. The hierarchical model showed high sensitivity and specificity for samples aged between zero and 30 days.
ANALYTICAL METHODS
(2023)
Article
Chemistry, Analytical
Erklaylle G. C. Silva, Carolina S. Silva, M. Fernanda Pimentel
Summary: This study evaluates the advantages and disadvantages of using infrared spectroscopy and chemometric techniques for document dating in forensics. It finds that storage conditions, such as temperature and exposure to UV radiation, have an influence on the aging process of paper. Regression models based on partial least squares are used to analyze the data.
Article
Chemistry, Analytical
Elena Naumovska, Gabriel Kofi Nzulu, Laura Mazzei, Arnaud Le Febvrier, Kristina Komander, Martin Magnuson, Max Wolff, Per Eklund, Maths Karlsson
Summary: Results from an infrared spectroscopy study on hydrated nanocrystalline films of BaZr1-xScxO3-x/2 with different Sc concentrations show variations in the O-H stretching bands, indicating different proton configurations. Higher Sc concentrations exhibit a distinct O-H stretching band, while lower Sc concentrations show a broader, weaker band.
VIBRATIONAL SPECTROSCOPY
(2024)
