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au:SILVA, RAPHAEL S. F.

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Impact of solar irradiance on gas exchange and growth of heliconia grown in a semi-arid region
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Souza, Rafaela R. de

; Silva Neto, José M. da

; Silva, Raphael R. da

; Souza, Geisse C. da S.

; Figueiredo, Hebert F. de

; Paiva Neto, Vespasiano B. de

; Borges, Mônica C. R. Z.

; Beckmann-Cavalcante, Márkilla Z.

Revista Brasileira de Engenharia Agrícola e Ambiental

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Oct 2023, Volumen 27 Nº 10 Paginas 757 - 763

Resumen: En Pt | Texto: En Pt | PDF: En | PDF: Pt

ABSTRACT Light is essential for providing energy for photosynthetic reactions and has a complex and not yet fully understood effect on heliconia growth and yield. Thus, the objective of this study was to evaluate the effect of light intensity on the growth and photosynthesis of heliconia under semi-arid conditions and to screen potential genotypes tolerant to high solar irradiation levels during the vegetative stage. The experiment was conducted in Petrolina, PE, Brazil, whose geographic coordinates are 09° 19’ 14” S, 40° 32’ 40” W, with an average altitude of 387 m. The experimental design used was in randomized blocks, arranged in a split-plot scheme, and the treatments were composed of two light intensities (full sun and 50% shading) and five genotypes (Heliconia psittacorum x H. spathocircinata cv. Golden Torch; H. psittacorum cv. Red Opal; H. bihai cv. Lobster Claw Two; H. rauliniana and H. rostrata). Growth and gas exchange assessments were conducted on the 100th day after the trial initiation. Light intensity (full sun and 50% shading) did not influence the rates of photosynthesis (A), stomatal conductance (gs), or transpiration (E) of plants. However, the isolated effect of the genotype revealed that plants of cv. Red Opal, H. bihai, H. rauliniana, and cv. Golden Torch had higher values of A, gs, and E. Overall, shading improved plant growth. We conclude that the genotypes H. psittacorum cv. Red Opal, and H. psittacorum cv. Golden Torch exhibited the greatest tolerances to high solar irradiance conditions.

RESUMO A luz é essencial por fornecer energia para as reações fotossintéticas e tem uma influência complexa e não totalmente compreendida no crescimento e produção de helicônias. Assim, objetivou-se avaliar o efeito da intensidade de luz sobre o crescimento e fotossíntese de helicônias em condições semiáridas e a triagem de genótipos potenciais tolerantes as condições de altos níveis de irradiação solar durante o estágio vegetativo. O experimento foi conduzido em Petrolina-PE, Brasil, cujas coordenadas geográficas são: 09° 19’ 14” S, 40° 32’ 40” O, com altitude média de 387 m. O delineamento experimental utilizado foi em blocos casualizados, arranjados em esquema de parcelas subdivididas, e os tratamentos foram compostos por duas intensidades de luz (pleno sol e sombreamento de 50%) e cinco genótipos (Heliconia psittacorum x H. spathocircinata cv. Golden Torch; H. psittacorum cv. Red Opal; H. bihai cv. Lobster Claw Two; H. rauliniana e H. rostrata). No 100° dia após o início do experimento foram realizadas avaliações de crescimento e trocas gasosas. As intensidades de luz (pleno sol e sombreamento 50%) não influenciaram a taxa fotossintética (A), condutância estomática (gs) e transpiração (E) das plantas. Porém, o efeito isolado do genótipo revela que plantas de cv. Red Opal, H. bihai, H. rauliniana e cv. Golden Torch apresentaram maiores valores de A, gs e E. Em geral, o sombreamento favoreceu maior incremento no crescimento das plantas. Conclui-se que os genótipos H. psittacorum cv. Red Opal e H. psittacorum cv. Golden Torch exibem maior tolerância às condições de elevada irradiância solar.

https://doi.org/10.1590/1807-1929/agriambi.v27n10p757-763

Characterization of Flavonoids Profiles in Polar Extracts from Croton grewioides Baill. Using Ultra-High Resolution Mass Spectrometry Baill UltraHigh Ultra High
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Nascimento, Pedro E. S. do

; Prado, Vilma M. J.

; Jesus, Raphael A. de

; Silva, Wenes R. da

; Wisniewski Jr., Alberto

; Sá Filho, José C. F.

; Blank, Arie F.

; Souza, Daniel A. de

; Wartha, Elma R. S. A.

; Nogueira, Paulo C. L.

; Moraes, Valéria R. S.

Journal of the Brazilian Chemical Society

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Jul 2023, Volumen 34 Nº 7 Paginas 937 - 948

Resumen: En | Texto: En | PDF: En

Research to identify plant bioactive compounds led to the evolution of extraction methods. This study optimized ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) to extract the flavonoids of Croton grewioides Baill. species contributing to characterize the polar extract profile and understand the antioxidant potential of these plant constituents. The use of experimental design and statistical treatments enabled the determination of the ideal conditions for each technique. The extracts of five accessions of C. grewioides were obtained under the optimized extraction conditions and were analyzed using ultra high-resolution mass spectrometry (FT-Orbitrap MS) operating at negative ionization mode for flavonoids detection. The accurate experimental mass obtained to the main compounds was used to attribute the molecular formula. Chemical structures of the main compounds detected were proposed using structure data bases. Chemometric analysis were performed with two FT-Orbitrap MS spectra samples using the identified metabolites and, the antioxidant activity data, showing that for this species the MAE was most effective in extracting the antioxidant compounds. It was possible to propose the structures for forty compounds in the C. grewioides extracts, demonstrating the excellent performance of the FT-Orbitrap MS in providing information on the chemical profile of polar compounds in plant extracts. methods ultrasoundassisted ultrasound assisted UAE (UAE microwaveassisted microwave (MAE Baill constituents technique C highresolution high resolution FTOrbitrap FT Orbitrap detection formula bases

https://doi.org/10.21577/0103-5053.20230004

Predicting soybean grain yield using aerial drone images
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Andrade Júnior, Aderson S. de

; Silva, Silvestre P. da

; Setúbal, Ingrid S.

; Souza, Henrique A. de

; Vieira, Paulo F. de M. J.

; Casari, Raphael A. das C. N.

Revista Brasileira de Engenharia Agrícola e Ambiental

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Jun 2022, Volumen 26 Nº 6 Paginas 466 - 476

Resumen: Pt En | Texto: Pt En | PDF: Pt | PDF: En

RESUMO O estudo objetivou avaliar a capacidade de índices de vegetação (IV) obtidos de imagens aéreas por veículo aéreo não tripulado em estimar a produtividade de grãos de soja, nas condições de solo e clima da microrregião de Teresina, Piauí, Brasil. Avaliou-se a cultivar de soja BRS-8980, em estádio R5, submetida a dois regimes hídricos (RH) (100 e 50% da evapotranspiração da cultura - ETc) e dois níveis de N (com e sem suplementação de N). O delineamento experimental foi o de blocos ao acaso, em parcelas subdivididas, sendo as parcelas os regimes hídricos e as subparcelas os níveis de nitrogênio, com cinco repetições. Cada parcela continha 20 linhas de 4,5 m de comprimento, espaçadas de 0,5 m entre linhas, com área de 45 m² e uma área útil para avaliação da produtividade de grãos de 6 m². Avaliaram-se 20 IV obtidos de imagens aéreas de câmera multiespectral, os quais foram correlacionados com medidas de produtividade de grãos em campo. Adotaram-se análises de correlação de Pearson, de regressão linear e de autocorrelação espacial (índice I de Moran global e local) para geração e análise de desempenho dos IV na predição da produtividade de grãos. Para validação dos modelos de regressão linear, usou-se os índices R2, RMSE e nRMSE. O modelo de predição baseado no EVI-2 apresenta elevada aleatoriedade espacial, para todos os tratamentos avaliados, e menores erros de predição iguais a 149,68 kg ha-1 (sem suplementação de N) e 173,96 kg ha-1 (com suplementação de N).

ABSTRACT This study aimed to evaluate the ability of vegetation indices (VIs) obtained from unmanned aerial vehicle (UAV) images to estimate soybean grain yield under soil and climate conditions in the Teresina microregion, Piaui state (PI), Brazil. Soybean cv. BRS-8980 was evaluated in stage R5 and submitted to two water regimes (WR) (100 and 50% of crop evapotranspiration - ETc) and two N levels (with and without N supplementation). A randomized block design in a split-plot scheme was used, in which the plots were the water regimes and the subplots N levels, with five replicates. Each plot contained twenty 4.5 m-long rows, spaced 0.5 m apart, with a total area of 45 and 6 m² study area for grain yield evaluations. Twenty VIs obtained from multispectral aerial images were evaluated and correlated with grain yield measurements in the field. Pearson’s correlation, linear regression, and spatial autocorrelation (Global and Local Moran’s I) were used to analyze the performance of the VIs in predicting grain yield. The R2, RMSE and nRMSE indices were used to validate the linear regression models. The prediction model based on EVI-2 exhibited high spatial randomness for all the treatments, and smaller prediction errors of 149.68 and 173.96 kg ha-1 (without and with N supplementation, respectively).

https://doi.org/10.1590/1807-1929/agriambi.v26n6p466-476

Influence of Homogenization and Annealing Temperatures on the Microstructure, Mechanical Properties, and Passive Properties of Cold Rolled 2205 Duplex Stainless Steel
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Assumpção, Raphael F.

; A. Júnior, Ricardo

; Silva, Amanda P.

; Dias, Francislaynne L.

; Santos, Dagoberto B.

; Sicupira, Dalila C.

Materials Research

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2022, Volumen 25 elocation e20220066

Resumen: En | Texto: En | PDF: En

Abstract The effects of homogenization, cold working, and subsequent annealing treatment were studied on the microstructural evolution, mechanical properties, and passive properties of duplex stainless steel (DSS). A hot-rolled 2205 DSS was subjected to two processing routes. In one, the DSS goes through an extra homogenization step at 1100 °C for 1800 s before cold rolling. After cold deformation (~75%) the specimens were isothermally annealed at 900, 1000, and 1100 °C for 180 s. The microstructure evolution was studied by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XDR). Mechanical properties were evaluated by microhardness and tensile tests. The electrochemical behaviors were investigated by potentiodynamic measurements, electrochemical impedance spectroscopy (EIS) and Mott-Schottky analysis (MS). Chemical composition of the lowest corrosion resistant passive film was assessed by X-ray photoelectron spectroscopy (XPS). Homogenization before cold rolling lowered strain hardening, slowing the microstructural transformation process. The thermomechanical process did not change the semiconductor type of the passive films. However, grain refinement after annealing improved the corrosion resistance in borate buffer solution. Cold rolling significantly decreased the corrosion resistance. The passive film of the specimen homogenized before cold rolling had the lowest corrosion resistance and high amounts of Cr(OH)3 and FeO.

https://doi.org/10.1590/1980-5373-mr-2022-0066

Schools reopening and the COVID-19 pandemic: a case study from Macaé, Rio de Janeiro, Brazil
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POZZOBON, ALLAN P. B.

; PETRY, ANA C.

; ZILBERBERG, CARLA

; BARROS, CINTIA M. DE

; NEPOMUCENO-SILVA, JOSÉ L.

; FEITOSA, NATÁLIA M.

; GOMES NETO, LUPIS R.

; RODRIGUES, BRUNO C.

; BRINDEIRO, RODRIGO M.

; NOCCHI, KEITY JAQUELINE C.V.

; MURY, FLAVIA B.

; SOUZA-MENEZES, JACKSON DE

; SILVA, MANUELA L. DA

; MEDEIROS, MARCIO JOSÉ DE

; GESTINARI, RAQUEL S.

; ALVARENGA, ALESSANDRA S. DE

; SILVA, CARINA A.O.

; SANTOS, DANIELE G. DOS

; SILVESTRE, DIEGO HENRIQUE

; SOUSA, GRAZIELE F. DE

; ALMEIDA, JANIMAYRI F. DE

; SILVA, JHENIFER N. DA

; BRANDÃO, LAYZA M.

; DRUMMOND, LEANDRO O.

; CARPES, RAPHAEL M.

; SANTOS, RENATA C. DOS

; PORTAL, TAYNAN M.

; TANURI, AMILCAR

; NUNES-DA-FONSECA, RODRIGO

Anais da Academia Brasileira de Ciências

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2022, Volumen 94 elocation e20211361

Resumen: En | Texto: En | PDF: En

Abstract Since the first reported case of COVID-19 in Brazil, the public and private educational system started to close. Up to November 2020, scientific discussions about the return of schooling activities have been rarely performed by the national scientific community and police-makers. The great delay of school returning in Brazil contrasts with successful international strategies of school reopening worldwide and seems counterintuitive with the reopening of non-essential activities. Here, important issues to be considered before and during school reopening are reviewed and discussed. COVID-19 testing is essential to avoid disease spreading, but high cost of individual RT-qPCRs impairs an extensive testing strategy for school returning. To reduce costs and increase the speed of diagnosis, we tested the efficiency of a pooled-sample PCR strategy in a cohort of the educational staff in the city of Macaé/RJ, finding five asymptomatic individuals (0,66%) among the 754 people tested. Thus, a polled-sample PCR testing strategy of the educational staff might prevent infection spreading in schools at a reasonable cost. We discuss how our test strategy could be coupled with internationally recognized safety rules to allow for a safe school return and how countries from different world regions are dealing with educational activities during COVID-19 pandemic.

https://doi.org/10.1590/0001-3765202220211361

Unexpected Rearrangement and Aromatization on Dehydration Reaction of the Bioactive Diterpenequinone 7α-Hydroxyroyleanone
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Leitão, Gilda G.

; Pinheiro, Aline G. L.

; Rezende, Victor L. D.

; Silva, Raphael S. F.

; Paula, Leonardo R.

; Soares, Deivid C.

; Saraiva, Elvira M.

Journal of the Brazilian Chemical Society

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Mar 2020, Volumen 31 Nº 3 Paginas 597 - 602

Resumen: En | Texto: En | PDF: En

7a-Hydroxyroyleanone is a bioactive diterpene isolated from leaves of Tetradenia riparia, active against tuberculosis and T. cruzi. In order to use this compound as starting material for the synthesis of compounds with enhanced bioactivity we aimed the dehydration of the 7-alpha-hydroxyl group of royleanone. The reaction performed in acetic acid and hydrochloric acid under reflux gave an unexpected chlorinated naphtoquinone, with aromatization and opening of one of the rings of the starting material, as major product, besides 6,7-dehydroroyleanone and a complex mixture of other products. The reaction products were purified by high-speed countercurrent chromatography with hexane-acetonitrile 1:1. Compounds were tested for their anti-leishmanial activity (L. amazonensis) pointing out a potential leishmanicidal agent which may favor the development of more effective therapies.

https://doi.org/10.21577/0103-5053.20190223 288 descargas

Application of LC-DAD Metabolic Fingerprinting in Combination with PCA for Evaluation of Seasonality and Extraction Method on the Chemical Composition of Accessions from Lippia alba (Mill) N. E. Brown and Biological Activities
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Jesus, Raphael A. de

; Prado, Vilma M. J.

; Pinto, Vanderson S.

; Silva, Valdenizia R.

; Santos, Luciano S.

; Nogueira, Paulo C. L.

; Navickiene, Sandro

; Pereira-Filho, Edenir R.

; Blank, Arie F.

; Bezerra, Daniel P.

; Soares, Milena B. P.

; Seidl, Claudia

; Cardoso, Carmen L.

; Moraes, Valéria R. S.

Journal of the Brazilian Chemical Society

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May 2019, Volumen 30 Nº 5 Paginas 978 - 987

Resumen: En | Texto: En | PDF: En

The methodology developed in this study through the acquisition of fingerprint chromatograms by liquid chromatography-diode array detector (LC-DAD), aided by principal component analysis, made it possible to assess, in a rational way, the chemical differences between six accessions of Lippia alba and to verify the influence of the method of extraction, the seasonality and the individuality of each accession on chemical composition of its extracts. Among all extracts analyzed against cancer cell lines, eight of them showed to be more promising against a human leukemia cell line (HL-60), displaying cell growth inhibition percentage ranging between 40.0 and 52.0%. In the inhibitory activity assays against acetylcholinesterase enzyme, all extracts showed weak inhibitory effect, with highlight only for six of them, which displayed inhibition ranging between 27.0 and 32.0%.

https://doi.org/10.21577/0103-5053.20180244 666 descargas

PHYTOCHEMISTRY INVESTIGATION OF CASEARIA ARBOREA (RICH.) URB. (SALICACEAE) AND ANTIMICROBIAL ANALYSIS OF ITS DITERPENE
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Leite-Ferreira, Maria D.

; Rocha-Souza, Maria S.

; Ramirez, Raphael R. de A.

; Chaves, Otemberg S.

; Teles, Yanna C. F.

; Pereira, Fillipe de O.

; Braz-Filho, Raimundo

; Lima, Edeltrudes de O.

; Sarquis, Rosangela do Socorro F. R.

; Silva, Tânia Maria Sarmento da

; Souza, Maria de Fátima Vanderlei de

Química Nova

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Jun 2018, Volumen 41 Nº 6 Paginas 619 - 622

Resumen: En | Texto: En | PDF: En

A phytochemical investigation from aerial parts of Casearia arborea (Rich.) Urb. (Salicaceae) led to isolation and identification of: sitosterol, 4-en-stigmast-3-one, 13-hydroxy-trans-ent-cleroda-3,14-diene,3-hydroxy-2-oxo-trans-ent-cleroda-3,14-diene (kolavelone), a mixture of 13-hydroxy-trans-ent-cleroda-3,14-diene and an ester ethyl hexadecanoate, kaempferol-3-O-a-L-arabinofuranoside and 4',5,7-trihydroxy-3',5'-dimethoxyflavone (tricin). The compounds have been described for the first time in this species. Five trihydroxy-flavone-hexoside derivatives have been identified by LC-ESI-HR-MS. The antimicrobial activity of kolavelone was evaluated against strains of Staphylococcus, Bacillus, Pseudomonas, Shigella and Candida spores, and its minimum inhibitory concentration (MIC) was determined. The results showed the antimicrobial activity of kolavelone against several bacteria and Candida tropicalis indicating its potential use as antimicrobial agent.

https://doi.org/10.21577/0100-4042.20170220 669 descargas

The Antinociceptive Effect of the Leaves and Flowers Ethanolic Extracts of Tabebuia aurea (Silva Manso) Benth & Hook. F. ex S. Moore
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Silva, Suellen Maria Albuquerque da

; Silva Neto, Geraldo José da

; Nascimento, Ivenis Raphael Cavalcante do

; Viana, Max Denisson Maurício

; Lima, Alyne Almeida de

; Bezerra, Pedro Henrique Simões

; Bastos, Maria Lysete de Assis

; Moreira, Magna Suzana Alexandre

; Campesatto, Eliane Aparecida

Brazilian Archives of Biology and Technology

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2018, Volumen 61 elocation e18180367

Resumen: En | Texto: En | PDF: En

ABSTRACT In view of the traditional use of Tabebuia aurea for treating pain and inflammation, the antinociceptive pharmacological potential of T. aurea ethanolic extracts (TAEE) was investigated through in vivo experimental models. First, the MTT assay was conducted to determine the potential cytotoxicity of the TAEEs. Afterwards, the acetic acid-induced writhing test and the formalin-, and glutamate-induced nociception tests were performed on Swiss adult mice treated with TAEEs (100 and 200 mg/kg doses, p.o.), or saline solution (control groups, 10mL/kg, p.o.), or standard drugs: dipyrone 40 mg/kg (p.o.), and morphine 5,7 mg/kg (i.p). In the MTT assay, none of the tested concentrations demonstrated signals of cytotoxicity. In the in vivo experimental models of acetic acid-induced writhing and glutamate-induced nociception, all TAEEs doses were able to statistically reduce the nociceptive response. However, the TAEEs did not show significant decrease in the amount of time that the animals spent licking the stimulated paw in the neurogenic phase of formalin-induced nociception test, differently of what was observed in the inflammatory phase. The results showed that T. aurea species induce an antinociceptive effect in rodents, which encourages the study of new drugs and contributes to the research on natural products.

https://doi.org/10.1590/1678-4324-2018180367 2834 descargas

10.

The influence of aerobic fitness status on ventilatory efficiency in patients with coronary artery disease
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Prado, Danilo M.L.

; Rocco, Enéas A.

; Silva, Alexandre G.

; Silva, Priscila F.

; Lazzari, Jaqueline M.

; Assumpção, Gabriela L.

; Thies, Sheyla B.

; Suzaki, Claudia Y.

; Puig, Raphael S.

; Furlan, Valter

Clinics

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Ene 2015, Volumen 70 Nº 1 Paginas 46 - 51

Resumen: En | Texto: En | PDF: En

OBJECTIVE: To test the hypotheses that 1) coronary artery disease patients with lower aerobic fitness exhibit a lower ventilatory efficiency and 2) coronary artery disease patients with lower initial aerobic fitness exhibit greater improvements in ventilatory efficiency with aerobic exercise training. METHOD: A total of 123 patients (61.0±0.7 years) with coronary artery disease were divided according to aerobic fitness status into 3 groups: group 1 (n = 34, peak VO2<17.5 ml/kg/min), group 2 (n = 67, peak VO2>17.5 and <24.5 ml/kg/min) and group 3 (n = 22, peak VO2>24.5 ml/kg/min). All patients performed a cardiorespiratory exercise test on a treadmill. Ventilatory efficiency was determined by the lowest VE/VCO2 ratio observed. The exercise training program comprised moderate-intensity aerobic exercise performed 3 times per week for 3 months. Clinicaltrials.gov: NCT02106533 RESULTS: Before intervention, group 1 exhibited both lower peak VO2 and lower ventilatory efficiency compared with the other 2 groups (p<0.05). After the exercise training program, group 1 exhibited greater improvements in aerobic fitness and ventilatory efficiency compared with the 2 other groups (group 1: ▵ = -2.5±0.5 units; group 2: ▵ = -0.8±0.3 units; and group 3: ▵ = -1.4±0.6 units, respectively; p<0.05). CONCLUSIONS: Coronary artery disease patients with lower aerobic fitness status exhibited lower ventilatory efficiency during a graded exercise test. In addition, after 3 months of aerobic exercise training, only the patients with initially lower levels of aerobic fitness exhibited greater improvements in ventilatory efficiency.

https://doi.org/10.6061/clinics/2015(01)09 1491 descargas

11.

Comprehensive two-dimensional gas chromatography coupled to time of flight mass spectrometry: new biomarker parameter proposition for the characterization of biodegraded oil
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Soares, Renata F.

; Pereira, Ricardo

; Silva, Raphael S. F.

; Mogollon, Leonardo

; Azevedo, Débora A.

Journal of the Brazilian Chemical Society

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Oct 2013, Volumen 24 Nº 10 Paginas 1570 - 1581

Resumen: Pt En | Texto: Pt En | PDF: Pt | PDF: En

Cromatografia gasosa bidimensional abrangente acoplada à espectrometria de massas por tempo de voo (GC×GC-TOFMS) é uma técnica apropriada para a elucidação da composição molecular de amostras petroquímicas, como óleos biodegradados. Biomarcadores foram separados, identificados e razões de biomarcadores convencionais foram determinados usando cromatografia gasosa acoplada à espectrometria de massas (GC-MS) e GC×GC-TOFMS. No cromatograma de íons extraídos m/z 123 + 177 + 191, coeluições entre terpanos tricíclicos, hopanos e 25-nor-hopanos com secohopanos foram resolvidas usando GC×GC-TOFMS. GC×GC-TOFMS permitiu a identificação da série completa dos 25-nor-hopanos, nor-gamacerano, C29 28-nor-espergulano e oleanano, que não foram identificados por GC-MS. A avaliação dos parâmetros geoquímicos dos óleos estudados indicou uma origem marinha e um ambiente deposicional sob condições anóxicas. A alta resolução cromatográfica e sensibilidade alcançada usando GC×GC-TOFMS permitiram sugerir três novos parâmetros geoquímicos para a caracterização de óleos altamente biodegradados. Estes resultados demonstram a superioridade da técnica GC×GC-TOFMS na separação e identificação de compostos individuais e não-alvos em óleos severamente biodegradados

Comprehensive two-dimensional gas chromatography with time of flight mass spectrometry (GC×GC-TOFMS) is an appropriate technique for the elucidation of molecular composition of petrochemical samples, such as biodegraded oils. Biomarkers were separated and identified, and conventional biomarker ratios were determined via gas chromatography-mass spectrometry (GC-MS) and GC×GC-TOFMS. In the extracted ion chromatogram m/z 123 + 177 + 191, coelutions between tricyclic terpanes, hopanes and 25-nor-hopanes with secohopanes were resolved by GC×GC-TOFMS. GC×GC-TOFMS allowed the identification of complete series of 25-nor-hopanes, nor-gammacerane, C29 28-nor-spergulanes and oleanane not identified by using GC-MS. The biomarker ratios from the studied oils indicated that they derived from marine source rock deposited under anoxic conditions. The higher chromatographic resolution and sensitivity achieved by using GC×GC-TOFMS allowed for three new parameters to characterize biodegraded oils. These results indicated the superiority of GC×GC-TOFMS for separation and identification of individual and non-target compounds in severely biodegraded oils.

https://doi.org/10.5935/0103-5053.20130198 4613 descargas

12.

Specificity and selectivity improvement in doping analysis using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry
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Barbosa, Samantha S.

; Leal, Felipe D.

; Padilha, Monica C.

; Silva, Raphael S. F.

; Pereira, Henrique Marcelo G.

; Aquino Neto, Francisco R.

; Silva Júnior, Ademário I. da

Química Nova

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2012, Volumen 35 Nº 5 Paginas 982 - 987

Resumen: En | Texto: En | PDF: En

Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry was used for the identification of forty doping agents. The improvement in the specificity was remarkable, allowing the resolution of analytes that could not be done by one-dimensional chromatographic systems. The sensitivity observed for different classes of prohibited substances was clearly below the value required by the World Anti-Doping Agency. In addition time-of-flight mass spectrometry gives full spectrum for all analytes without any interference from the matrix, resulting in selectivity improvements. These results could support the implementation of an exhaustive monitoring approach for hundreds of doping agents in a single injection.

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13.

Comprehensive two-dimensional gas chromatography with time of flight mass spectrometry applied to analysis of Fischer-Tropsch synthesis products obtained with and without carbon dioxide addition to feed gas
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Silva, Raphael S. F.

; Tamanqueira, Juliana B.

; Dias, Julio César M.

; Passarelli, Fábio M.

; Bidart, Antonio Marcos F.

; Aquino Neto, Francisco R.

; Azevedo, Débora A.

Journal of the Brazilian Chemical Society

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Nov 2011, Volumen 22 Nº 11 Paginas 2121 - 2126

Resumen: Pt En | Texto: Pt En | PDF: Pt | PDF: En

A cromatografia gasosa bidimensional abrangente acoplada à espectrometria de massas por tempo de vôo (CG×CG-EMTDV) foi aplicada para avaliar o efeito do CO2 sobre a distribuição dos n-alcanos, alcanos ramificados, alquenos e compostos oxigenados em produtos da reação de Fischer-Tropsch. Coeluições de material não resolvido observadas em CG convencional foram resolvidas por CG×CG-EMTDV.

Comprehensive two-dimensional gas chromatography coupled to time of flight mass spectrometry (GC × GC-TOFMS) was applied to evaluate the CO2 effect on distribution of n-alkanes, branched alkanes, alkenes and oxygen-containing compounds in Fischer-Tropsch products. GC × GC-TOFMS was able to resolve the unresolved compounds observed in conventional GC.

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14.

Yeast communities in two Atlantic rain Forest fragments in Southeast Brazil
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Pimenta, Raphael S.

; Alves, Priscila D. D.

; Almeida, Gabriel M. F.

; Silva, Juliana F.M

; Morais, Paula B.

; Corrêa Jr., Ary

; Rosa, Carlos A.

Brazilian Journal of Microbiology

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Mar 2009, Volumen 40 Nº 1 Paginas 90 - 95

Resumen: Pt En | Texto: Pt En | PDF: Pt | PDF: En

O objetivo deste trabalho foi estudar as comunidades de leveduras associadas a frutos, cogumelos, exudatos de árvores e moscas do gênero Drosophila, em dois fragmentos de Mata Atlântica no Estado de Minas Gerais, Brasil. Foram coletadas 456 amostras no Parque Estadual do Rio Doce e 142 na Estação Ecológica da Universidade Federal de Minas Gerais. Destas amostras foram obtidas 608 isolados de levedura, distribuídas em 71 espécies. Entre os isolados obtidos a partir do Parque Estadual do Rio Doce, 17 foram provenientes de frutos, 12 de cogumelos, 13 de exudatos de árvores e 299 de Drosophila spp. A Estação Ecológica da Universidade Federal de Minas Gerais possibilitou a obtenção de 24 isolados de frutos e 243 de Drosophila spp. Foram observadas comunidades distintas de leveduras associadas a Drosophila, frutos, cogumelos e exudatos de árvores. O maior número de espécies foi obtido em drosófilas, sugerindo que estas moscas são vetores naturais destes microrganismos.

We studied the yeast communities associated with fruits, mushrooms, tree exudates, and flies of the genus Drosophila, in two Atlantic Rain Forest fragments in state of Minas Gerais, Brazil. A total of 456 samples were collected from Rio Doce State Park and 142 from Ecological Station of Universidade Federal de Minas Gerais. From these samples, 608 yeast isolates were obtained, belonging to 71 different species. Among the yeasts isolated from Rio Doce State Park, 17 isolates were recovered from fruits, 12 from mushrooms, 13 from tree exudates, and 299 from Drosophila spp. In the Ecological Station of Universidade Federal de Minas Gerais, 24 isolates were recovered from fruits and 243 from Drosophila spp. Distinct communities of yeast were observed in Drosophila flies, fruits, mushrooms and tree exudates. The highest number of yeast species was recovered from Drosophila flies suggesting that flies are the natural vectors of these microorganisms.

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15.

Chemoselective oxidation of benzophenazines by m-CPBA: n-oxidation vs. oxidative cleavage
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Silva, Raphael S. F.

; Amorim, Mauro B. de

; Pinto, Maria do Carmo F. R.

; Emery, Flávio S.

; Goulart, Marília O. F.

; Pinto, Antonio V.

Journal of the Brazilian Chemical Society

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2007, Volumen 18 Nº 4 Paginas 759 - 764

Resumen: Pt En | Texto: Pt En | PDF: Pt | PDF: En

Quimiosseletividade é observada, após reação de oxidação, utilizando-se m-CPBA, a partir da piranobenzo[a]fenazina e da furanobenzo[a]fenazina, derivadas, respectivamente da beta-lapachona e da nor-beta-lapachona. A fenazina pirânica forneceu macrolactonas, principalmente, enquanto a fenazina furânica conduziu a um único produto: o N-8 óxido da fenazina. Objetivando entender essa diferença de reatividade, uma nova fenazina furânica foi sintetizada, tendo como característica principal, a presença da ligação dupla em um sítio menos encoberto estericamente do que aquele presente no derivado nor-beta-lapachônico. Essa furanofenazina, após oxidação com m-CPBA, forneceu, principalmente, a macrolactona esperada. Esses resultados experimentais, aliados a cálculos mecânico-moleculares do estado fundamental dos substratos, permitiram sugerir que a quimiosseletividade observada pode ter controle estérico, relacionado à presença dos grupos substituintes metila geminados, que dificultam a aproximação do oxidante. Muitos dos compostos sintetizados são relatados, pela primeira vez, no presente artigo.

Chemoselectivity is observed when a pyran-benzo[a]phenazine and a furan-benzo[a]phenazine from beta-lapachone and nor-beta-lapachone, respectively, were submitted to oxidation by m-CPBA. The pyran phenazine furnished mainly macrolactones, while the furan one led exclusively to a phenazine N-8 oxide. To understand this difference in reactivity, we synthesized a new furan phenazine, with the reactive double bond site less hindered than that of the derivative from nor-beta-lapachone. This furan phenazine, upon oxidation with m-CPBA, furnished mainly the expected macrolactone. These experimental results, along with preliminary analysis based on mechanical molecular calculations of the ground state of the substrates, allowed us to suggest that the observed chemoselectivity has a steric oxidant approach control origin, related to the presence of the geminal methyl groups in the phenazine structure. Several of the synthesized compounds are, herein, reported for the first time.

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