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Fourier-Based PLL Applied for Selective Harmonic Estimation in Electric Power Systems
Santos, Claudio H.G.,Ferreira, Reginaldo V.,Silva, Sidelmo Magalhaes,Cardoso Filho, Braz J. The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.5
In this paper, the Fourier-based PLL (Phase-locked Loop) is introduced with a new structure, capable of selective harmonic detection in single and three-phase systems. The application of the FB-PLL to harmonic detection is discussed and a new model applicable to three-phase systems is introduced. An analysis of the convergence of the FB-PLL based on a linear model is presented. Simulation and experimental results are included for performance analysis and to support the theoretical development. The decomposition of an input signal in its harmonic components using the Fourier theory is based on previous knowledge of the signal fundamental frequency, which cannot be easily implemented with input signals with varying frequencies or subjected to phase-angle jumps. In this scenario, the main contribution of this paper is the association of a phase-locked loop system, with a harmonic decomposition and reconstruction method, based on the well-established Fourier theory, to allow for the tracking of the fundamental component and desired harmonics from distorted input signals with a varying frequency, amplitude and phase-angle. The application of the proposed technique in three-phase systems is supported by results obtained under unbalanced and voltage sag conditions.
Boron nitride nanotube-CREKA peptide as an effective target system to metastatic breast cancer
Ferreira Tiago Hilário,de Oliveira Freitas Luiza Baptista,Fernandes Renata Salgado,dos Santos Virgílio Mateus,Resende Jarbas Magalhães,Cardoso Valbert Nascimento,de Barros André Luís Branco,de Sousa E 한국약제학회 2020 Journal of Pharmaceutical Investigation Vol.50 No.5
Purpose The development of nanomaterials that are capable of recognizing disease-specific biomarkers with high sensitivity and specificity is related to several advances in the field of nanomedicine. Furthermore, the targeted delivery of anticancer agents to tumor tissues enhances their efficiency and reduces their toxic side effects. Boron nitride nanotubes (BNNTs) are nanostructured materials, analog to carbon nanotubes, which present good biocompatibility and morphology suitable for tumor cell internalization. CREKA is a pentapeptide that has a high affinity to fibrin, a protein found in the new tumor vessels in the early stages of metastasis and in thrombosis regions. Methods In this study BNNTs were chemically functionalized with the peptide CREKA, and this system was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), zeta potential, scanning electron microscopy, and transmission electron microscopy. Results After the mentioned chemical steps, the FTIR analysis shows an organic phase related to the CREKA, TGA indicates that about 10% of the peptide is firmly attached to BNNT surface. In addition, the radiolabeling process was successful, achieving the purity required for the biodistribution study. In vivo experiments showed that a considerable amount of BNNTCREKA was accumulated at the tumor and metastasis sites. Conclusion The present results indicate an effective targeting of the system to tumor and metastasis sites. Further studies can reveal potential applications of functionalized BNNTs in cancer treatment.
Anderson Santos Souza,Marcos Almeida Bezerra,Uillian Mozart Ferreira Mata Cerqueira,Caiene Jesus Oliveira Rodrigues,Bianca Cotrim Santos,Cleber Galvão Novaes,Erica Raina Venâncio Almeida 한국식품과학회 2024 Food Science and Biotechnology Vol.33 No.6
Principal component analysis (PCA) is currently one of the most used multivariate data analysis techniques for evaluating information from food analysis. In this review, a brief introduction to the theoretical principles that underlie PCA will be given, in addition to presenting the most commonly used computer programs. An example from the literature was discussed to illustrate the use of this chemometric tool and interpretation of graphs and parameters obtained. A list of recently published articles will also be presented, in order to show the applicability and potential of the technique in the food analysis field.
Analysis of Different Electric Current Frequencies in Soil Apparent Conductivity
dos Santos Fernando Ferreira Lima,de Queiroz Daniel Marçal,Valente Domingos Sárvio Magalhães,Khorsandi Farzaneh,de Moura Araújo Guilherme 한국농업기계학회 2023 바이오시스템공학 Vol.48 No.2
Purpose The electrical resistivity method is commonly used to identify areas with similar soil characteristics by measuring the soil’s apparent electrical conductivity (EC a ). However, the ideal frequency range to be used and the infl uence of the signal frequency on EC a values obtained by sensors is still uncertain. This study aimed to (1) evaluate the eff ect of electric current frequency on EC a values and (2) evaluate the correlation between EC a values obtained from diff erent frequencies and soil attributes of agronomic interest, such as soil water content and pH. EC a determinations were obtained in four experimental areas using six diff erent frequencies of electric current (1, 5, 10, 20, 30, and 40 Hz). Methods The infl uence of the electric current signal frequency on the value obtained by the sensor was analyzed by linear regressions in all experimental areas, followed by the F- test ( α = 0.05). Pearson’s correlations ( α = 0.05) were calculated to quantify the relationships between EC a and soil physical and chemical attributes, for each frequency of the electric current signal of the sensor. Results Statistical analyses indicated that the electric current frequency does not signifi cantly aff ect the measured conductivity value. According to the chi-square test ( p ≤ 0.05), the number of signifi cant correlations between EC a and soil physical and chemical attributes was homogeneous for all frequencies. The F -test indicated that the frequency of the electric current had no signifi cant eff ect on EC a in 90% of the experimental points. Conclusion It was shown that all frequencies in the range of 1 to 40 Hz can be used to correlate EC a values with chemical and physical soil attributes, such as soil water content ( r = 0.73, p < 0.05) and exchangeable calcium content ( r = 0.66, p < 0.05).
Priscila Gonçalves Ferreira,Fernando Augusto da Silveira,Raquel Cristina Vieira dos Santos,Hugo Leonardo André Genier,Raphael Hermano Santos Diniz,José Ivo Ribeiro Júnior,Luciano Gomes Fietto,Flávia M 한국식품과학회 2015 Food Science and Biotechnology Vol.24 No.4
The simultaneous saccharification and fermentation (SSF) process is a promising strategy to obtain ethanol from cellulosic biomass. In this study, sugarcane bagasse was supplemented with ricotta whey to increase the sugar, vitamin, and trace metal concentrations in the fermentation medium. The optimum conditions for SSF ethanol production from a mixture of sugarcane bagasse and ricotta whey produced by Kluyveromyces marxianus CCT 7735 were evaluated considering five factors: cellulase concentration, cellulosic biomass concentration, pH, temperature, and agitation. The highest ethanol yield was 49.65 g/L with a cellulosic biomass of 80 g/L, pH value of 5.05, agitation at 65 rpm and temperature of 39.2ºC. The results demonstrated that a mixture of the cellulosic residue of sugarcane bagasse and ricotta whey is promising for ethanol production because the ethanol yield in the mixture was higher than that in single substrate of sugarcane bagasse.
Epidemiology of Abdominal Obesity among Adolescents from a Brazilian State Capital
Diego Augusto Santos Silva,Andreia Pelegrini,João Marcos Ferreira de Lima e Silva,Edio Luiz Petroski 대한의학회 2011 Journal of Korean medical science Vol.26 No.1
The objective of this study was to investigate the effects of socioeconomic, demographic and lifestyle factors on abdominal obesity in adolescents from a Brazilian state capital. In this cross-sectional study, 656 high school students (423 girls and 233 boys) from public schools, ranging in age from 14 to 19 yr, were evaluated. Abdominal obesity was identified based on waist circumference. Socioeconomic data (socioeconomic status,household head’s education, and school grade), demographic data (gender and age), and information regarding lifestyle (physical activity, eating habits, aerobic fitness, and nutritional status) were collected. Logistic regression was used for multivariate analysis. The prevalence of abdominal obesity was 6.6% (95% confidence interval [CI]: 4.6-8.4). Being in the second (odds ratio [OR] = 0.41; 95% CI: 0.19-0.88) or third year (OR = 0.18;95% CI: 0.06-0.59) of high school was a protective factor against abdominal obesity. In addition, students presenting low aerobic fitness (OR = 4.10; 95% CI: 1.62-10.4) and those with excess weight (OR = 208.6; 95% CI: 47.7-911.7) had a higher probability of abdominal obesity. In conclusion, demographic factors such as school grade, lifestyle habits, low aerobic fitness and excess weight are associated with central obesity.
Moreira, MarianaA.,Santos, Joã,o C.,Ferreira, Alexandre F. P.,Loureiro, José,M.,Ragon, Florence,Horcajada, Patricia,Shim, Kyu-E.,Hwang, Young-K.,Lee, U.-Hwang,Chang, Jong-S.,Serre, Christi American ChemicalSociety 2012 Langmuir Vol.28 No.13
<P>Powder, agglomerates, and tablets of the microporous zirconium(IV)terephthalate metal–organic framework UiO-66 were evaluatedfor the selective adsorption and separation of xylene isomers in theliquid phase using <I>n</I>-heptane as the eluent. Pulseexperiments, performed at 313 K in the presence of <I>n</I>-heptane, revealed the <I>o</I>-xylene preference of thismaterial, which was further confirmed by binary and multicomponentbreakthrough experiments in the presence of <I>m</I>- and <I>p</I>-xylene, resulting in selectivities at 313 K of 1.8 and2.4 with regards to <I>m</I>-xylene and <I>p</I>-xylene, respectively. Additionally, because <I>p</I>-xyleneis the less retained isomer, UiO-66 presents a selectivity patternthat is reverse of that of the xylenes' molecular dimension with respectto shape selectivity. The shaping of the material as tablets did notsignificantly change its selectivity toward the <I>o</I>-xylene isomer or toward <I>p</I>-xylene, which was theless retained isomer, despite a loss in capacity. Finally, the selectivitybehavior of UiO-66 in the liquid <I>n</I>-heptane phasemakes it a suitable material for <I>o</I>-xylene separationin the extract (heavy product) or <I>p</I>-xylene separationin the raffinate (light product) by simulated moving bed technology.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2012/langd5.2012.28.issue-13/la3004118/production/images/medium/la-2012-004118_0011.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/la3004118'>ACS Electronic Supporting Info</A></P>