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CHEMISTRY (656 journals)            First | 1 2 3 4 | Last

Showing 401 - 600 of 735 Journals sorted alphabetically
Journal of Pure and Applied Chemistry Research     Open Access   (Followers: 3)
Journal of Raman Spectroscopy     Hybrid Journal   (Followers: 17)
Journal of Research Updates in Polymer Science     Hybrid Journal   (Followers: 3)
Journal of Saudi Chemical Society     Open Access  
Journal of Solid State Chemistry     Hybrid Journal   (Followers: 14)
Journal of Solution Chemistry     Hybrid Journal   (Followers: 2)
Journal of Structural Chemistry     Hybrid Journal   (Followers: 1)
Journal of Sulfur Chemistry     Hybrid Journal   (Followers: 3)
Journal of Supercritical Fluids     Hybrid Journal   (Followers: 4)
Journal of Superhard Materials     Hybrid Journal   (Followers: 1)
Journal of Surface Science and Technology     Hybrid Journal  
Journal of Surfactants and Detergents     Hybrid Journal   (Followers: 3)
Journal of Taibah University for Science     Open Access   (Followers: 1)
Journal of the American Chemical Society     Hybrid Journal   (Followers: 377)
Journal of the American Society for Mass Spectrometry     Hybrid Journal   (Followers: 31)
Journal of the American Society of Brewing Chemists     Full-text available via subscription   (Followers: 3)
Journal of the Bangladesh Chemical Society     Open Access  
Journal of the Chilean Chemical Society     Open Access   (Followers: 2)
Journal of the Iranian Chemical Society     Hybrid Journal  
Journal of the Korean Society for Applied Biological Chemistry     Hybrid Journal   (Followers: 1)
Journal of the Mexican Chemical Society     Open Access   (Followers: 2)
Journal of the Serbian Chemical Society     Open Access  
Journal of the Turkish Chemical Society, Section A : Chemistry     Open Access  
Journal of Theoretical and Computational Chemistry     Hybrid Journal   (Followers: 10)
JPC - Journal of Planar Chromatography - Modern TLC     Full-text available via subscription   (Followers: 2)
Jurnal Inovasi Pendidikan Kimia     Open Access   (Followers: 5)
Jurnal Katalisator     Open Access  
Jurnal Kimia (Journal of Chemistry)     Open Access  
Jurnal Kimia Riset     Open Access  
Jurnal Penelitian Sains (JPS)     Open Access  
Karadeniz Chemical Science and Technology     Open Access  
Karbala International Journal of Modern Science     Open Access   (Followers: 3)
Kinetics and Catalysis     Hybrid Journal   (Followers: 5)
Konfigurasi : Jurnal Pendidikan Kimia dan Terapan     Open Access  
Korea-Australia Rheology Journal     Hybrid Journal  
Langmuir     Hybrid Journal   (Followers: 64)
Latvian Journal of Chemistry     Open Access   (Followers: 1)
Lebensmittelchemie     Hybrid Journal   (Followers: 1)
Lipid Insights     Open Access  
Luminescence     Hybrid Journal   (Followers: 5)
Macromolecular Materials & Engineering     Hybrid Journal   (Followers: 5)
Macromolecular Rapid Communications     Hybrid Journal   (Followers: 10)
Macromolecular Research     Hybrid Journal   (Followers: 2)
Macromolecular Symposia     Hybrid Journal   (Followers: 3)
Macromolecular Theory and Simulations     Hybrid Journal   (Followers: 2)
Macromolecules     Hybrid Journal   (Followers: 52)
Maghrebian Journal of Pure and Applied Science     Full-text available via subscription  
Magnetic Resonance in Chemistry     Hybrid Journal   (Followers: 10)
Magnetochemistry     Open Access  
Marine Chemistry     Hybrid Journal   (Followers: 7)
Marine Drugs     Open Access   (Followers: 3)
MATEC Web of Conferences     Open Access   (Followers: 5)
Materials Characterization     Hybrid Journal   (Followers: 35)
Materials Chemistry Frontiers     Full-text available via subscription  
Materials Horizons     Full-text available via subscription   (Followers: 3)
Materials Research Bulletin     Hybrid Journal   (Followers: 28)
Materials Science Monographs     Full-text available via subscription   (Followers: 3)
Materials Science-Poland     Open Access   (Followers: 1)
Materials Sciences and Applications     Open Access   (Followers: 3)
MedChemComm     Full-text available via subscription   (Followers: 6)
Medicinal Chemistry Research     Hybrid Journal   (Followers: 12)
Mediterranean Journal of Chemistry     Open Access  
Metallography, Microstructure, and Analysis     Hybrid Journal   (Followers: 2)
Metallomics     Full-text available via subscription  
Micro and Nano Systems Letters     Open Access   (Followers: 6)
Microchimica Acta     Hybrid Journal   (Followers: 2)
Microporous and Mesoporous Materials     Hybrid Journal   (Followers: 10)
Modern Chemistry & Applications     Open Access   (Followers: 1)
Modern Research in Catalysis     Open Access   (Followers: 1)
Molbank     Open Access   (Followers: 1)
Molecular Astrophysics     Full-text available via subscription   (Followers: 1)
Molecules     Open Access   (Followers: 7)
Molecules and Cells     Hybrid Journal   (Followers: 1)
Monatshefte für Chemie - Chemical Monthly     Hybrid Journal   (Followers: 4)
Mongolian Journal of Chemistry     Open Access  
Moroccan Journal of Chemistry     Open Access  
Moroccan Journal of Heterocyclic Chemistry     Open Access  
Moscow University Chemistry Bulletin     Hybrid Journal   (Followers: 1)
MRS Bulletin     Full-text available via subscription   (Followers: 4)
MRS Online Proceedings     Full-text available via subscription   (Followers: 1)
Nachrichten aus der Chemie     Hybrid Journal   (Followers: 17)
Nano Convergence     Open Access   (Followers: 1)
Nano Reviews & Experiments     Open Access   (Followers: 14)
Nanochemistry Research     Open Access  
Nanocontainers     Open Access   (Followers: 1)
Nanomaterials and the Environment     Open Access   (Followers: 1)
Nanoscale     Full-text available via subscription   (Followers: 20)
Nanoscale Advances     Open Access   (Followers: 1)
Nanoscale Research Letters     Open Access   (Followers: 9)
Nanoscience and Nanotechnology Letters     Full-text available via subscription   (Followers: 22)
Nanospectroscopy     Open Access   (Followers: 2)
Natural Product Reports     Full-text available via subscription   (Followers: 10)
Natural Products Chemistry & Research     Open Access   (Followers: 1)
Natural Products Journal     Hybrid Journal   (Followers: 1)
Natural Science     Open Access   (Followers: 9)
Natural Volatiles & Essential Oils     Open Access  
Nature Chemistry     Full-text available via subscription   (Followers: 92)
Nature Protocols     Full-text available via subscription   (Followers: 72)
Nature Reviews Chemistry     Hybrid Journal   (Followers: 8)
New Journal of Chemistry     Full-text available via subscription   (Followers: 20)
Nitric Oxide     Hybrid Journal  
Nitrogen     Open Access   (Followers: 1)
Nova Biotechnologica et Chimica     Open Access  
Nukleonika     Open Access   (Followers: 2)
Open Chemistry     Open Access   (Followers: 6)
Open Chemistry Journal     Open Access  
Open Conference Proceedings Journal     Open Access  
Open Journal of Composite Materials     Open Access   (Followers: 20)
Open Journal of Inorganic Non-metallic Materials     Open Access   (Followers: 4)
Open Journal of Medicinal Chemistry     Open Access   (Followers: 5)
Open Journal of Polymer Chemistry     Open Access   (Followers: 13)
Open Journal of Synthesis Theory and Applications     Open Access  
Open Medicinal Chemistry Journal     Open Access  
Orbital - The Electronic Journal of Chemistry     Open Access   (Followers: 3)
Organic & Biomolecular Chemistry     Full-text available via subscription   (Followers: 74)
Organometallics     Hybrid Journal   (Followers: 22)
Organosulfur Chemistry     Full-text available via subscription  
Oxidation of Metals     Hybrid Journal   (Followers: 18)
Peptidomics     Open Access  
Pharmaceuticals     Open Access   (Followers: 6)
Pharmaceutics     Open Access   (Followers: 4)
Phosphorus, Sulfur, and Silicon and the Related Elements     Hybrid Journal   (Followers: 2)
Photochemistry and Photobiology     Hybrid Journal   (Followers: 4)
Physical Sciences Reviews     Hybrid Journal   (Followers: 1)
Physics and Materials Chemistry     Open Access   (Followers: 2)
Phytochemistry     Hybrid Journal   (Followers: 6)
Phytochemistry Letters     Full-text available via subscription   (Followers: 4)
Plasma     Open Access   (Followers: 2)
Plasma Chemistry and Plasma Processing     Hybrid Journal   (Followers: 6)
Polímeros : Ciência e Tecnologia     Open Access  
Polycyclic Aromatic Compounds     Hybrid Journal  
Polyhedron     Hybrid Journal   (Followers: 4)
Polymer Chemistry     Full-text available via subscription   (Followers: 25)
Polymer Degradation and Stability     Hybrid Journal   (Followers: 26)
Polymer Engineering & Science     Hybrid Journal   (Followers: 17)
Polymer Reviews     Hybrid Journal   (Followers: 36)
Polymer Science Series D     Hybrid Journal   (Followers: 4)
Polymer Testing     Hybrid Journal   (Followers: 129)
Polymer-Plastics Technology and Engineering     Hybrid Journal   (Followers: 5)
Polymers     Open Access   (Followers: 19)
Procedia Chemistry     Open Access  
Proceedings in Radiochemistry. A Supplement to Radiochimica Acta     Open Access   (Followers: 1)
Proceedings of the Combustion Institute     Full-text available via subscription   (Followers: 8)
Processes     Open Access  
Progress in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 1)
Progress in Lipid Research     Hybrid Journal   (Followers: 3)
Progress in Organic Coatings     Hybrid Journal   (Followers: 9)
Progress in Polymer Science     Full-text available via subscription   (Followers: 38)
Progress in Reaction Kinetics and Mechanism     Full-text available via subscription   (Followers: 2)
Progress in Solid State Chemistry     Full-text available via subscription   (Followers: 3)
Progress in Surface Science     Full-text available via subscription   (Followers: 4)
Protein Science     Hybrid Journal   (Followers: 46)
Pure and Applied Chemistry     Hybrid Journal   (Followers: 8)
Química Nova     Open Access  
Quimica Viva     Open Access  
Radiochemistry     Hybrid Journal   (Followers: 2)
Rapid Communications in Mass Spectrometry     Hybrid Journal   (Followers: 31)
Reaction Chemistry & Engineering     Hybrid Journal  
Reaction Kinetics, Mechanisms and Catalysis     Hybrid Journal   (Followers: 2)
Recent Advances in Phytochemistry     Full-text available via subscription   (Followers: 3)
Recyclable Catalysis     Open Access   (Followers: 2)
Reports in Theoretical Chemistry     Open Access  
Research and Reports in Medicinal Chemistry     Open Access   (Followers: 3)
Research Journal of Phytochemistry     Open Access   (Followers: 3)
Review Journal of Chemistry     Hybrid Journal  
Reviews in Chemical Engineering     Hybrid Journal   (Followers: 6)
Reviews in Mineralogy and Geochemistry     Hybrid Journal   (Followers: 4)
Reviews of Adhesion and Adhesives     Full-text available via subscription  
Revista Boliviana de Química     Open Access  
Revista CENIC. Ciencias Quimicas     Open Access   (Followers: 2)
Revista Ciências Exatas e Naturais : RECEN     Open Access  
Revista Colombiana de Química     Open Access   (Followers: 1)
Revista Cubana de Química     Open Access  
Revista de Ciencia y Tecnología     Open Access  
Revista de Ciencias     Open Access  
Revista de la Societat Catalana de Química     Open Access  
Revista Debates em Ensino de Química     Open Access  
Revista ION     Open Access  
Revista Química : ciência, tecnologia e sociedade     Open Access  
RHAZES : Green and Applied Chemistry     Open Access  
RSC Advances     Open Access   (Followers: 33)
Rubber Chemistry and Technology     Full-text available via subscription   (Followers: 2)
Russian Chemical Reviews     Full-text available via subscription   (Followers: 4)
Russian Journal of Bioorganic Chemistry     Hybrid Journal   (Followers: 2)
Russian Journal of Coordination Chemistry     Hybrid Journal   (Followers: 1)
Russian Journal of General Chemistry     Hybrid Journal   (Followers: 1)
Russian Journal of Inorganic Chemistry     Hybrid Journal  
Sainstek : Jurnal Sains dan Teknologi     Open Access  
Science China Chemistry     Hybrid Journal   (Followers: 2)
Sciences & Technologie A : sciences exactes     Open Access  
Scientific Journal of Frontier Chemical Development     Open Access   (Followers: 2)
Scientific Reports     Open Access   (Followers: 76)
Sensors and Actuators B: Chemical     Hybrid Journal   (Followers: 17)
Separation & Purification Reviews     Hybrid Journal   (Followers: 8)
Separation Science and Technology     Hybrid Journal   (Followers: 14)
Separations     Open Access   (Followers: 6)
Silicon Chemistry     Hybrid Journal   (Followers: 2)
Smart Materials Research     Open Access   (Followers: 7)
Soft     Open Access  
Soft Nanoscience Letters     Open Access   (Followers: 2)

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Revista Colombiana de Química
Journal Prestige (SJR): 0.115
Number of Followers: 1  

  This is an Open Access Journal Open Access journal
ISSN (Print) 0120-2804
Published by SciELO Homepage  [736 journals]
  • Selection of reference genes for transcriptional analysis in the
           pathosystem carnation (Dianthus Caryophyllus L.) - Fusarium oxysporum f.
           sp. dianthi

    • Abstract: Resumen En el presente trabajo se seleccionaron y validaron genes de referencia para estudios transcripcionales en el modelo clavel -Fusarium oxysporum f. sp. dianthi. Para ello, se seleccionaron genes asociados a procesos básicos celulares que han sido usados como genes de referencia en otros modelos planta-patógeno y se determinó el efecto de la inoculación del patógeno sobre su expresión. Se realizó un diseño de cebadores para los diferentes genes candidatos con el fin de verificar tanto su presencia en el genoma de claveles cultivados en Colombia, como su transcripción constitutiva en los diferentes tejidos por medio de la técnica de transcripción reversa y posterior reacción en cadena de la polimerasa (RT-PCR por sus siglas en ingles). Posteriormente, se evaluaron los niveles transcripcionales de los genes candidatos usando RT-qPCR en tallos y raíces de dos variedades con diferentes niveles de resistencia a la enfermedad, que fueron inoculados con este patógeno. La validación estadística realizada, usando ANOVA y los programas GeNorm y Normfinder, determinó que los genes codificantes para una histona H3 y el ARNr18S no presentan variación en sus niveles de expresión por efecto de la inoculación, permitiendo su uso como genes de referencia en estudios transcripcionales en esta interacción planta-patógeno. In this research, reference genes were validated for transcriptional studies in the pathosystem carnation - Fusarium oxysporum f. sp. dianthi. Genes associated with basic cellular processes that have been used as reference genes in other plant-pathogen models were selected and the effect of the inoculation with the pathogen on their expression was determined. For this, it was necessary to design primers for each candidate genes to check their presence in the genome of carnations grown in Colombia and their constitutive transcription in different tissues of the plant using reverse transcription subsequent polymerase chain reaction (RT-PCR). The transcriptional levels of the candidate genes were evaluated using RT-qPCR in stems and roots inoculated with this pathogen for two cultivars with different levels of resistance to the disease. According to the statistical validation carried out using ANOVA and the GeNorm and Normfinder programs, the genes coding for a histone H3 and rRNA18S did not show any significant variation in their expression levels due to inoculation, so they can be used as reference genes in transcriptional studies in this plant-pathogen interaction.Resumo Neste trabalho foram validados genes de referencia para estudos de transcrição no modelo cravo - Fusarium oxysporum f. sp. dianthi. Genes associados a processos básicos celulares, anteriormente usados como genes de referencia noutros modelos planta-patógeno, foram selecionados e se determinou o efeito, sobre a sua expressão, que apresentava a inoculação com o patógeno. Foi realizado um desenho de iniciadores para os diferentes genes candidatos para verificou a sua presença no genoma de cravos cultivados na Colômbia, e uma transcrição constitutiva em diferentes tecidos da planta com a técnica de transcrição reversa e posterior reação em cadeia da polimerase (RT-PCR). Em seguida, os níveis de transcrição dos genes candidatos foram avaliados por RT-qPCR em caules e raízes de duas variedades com diferentes níveis de resistência à doença, que tinham sido inoculados com o patógeno. A validação estatística realizada por ANOVA y com os programas GeNorm y Normfinder, permitiram determinar que os genes que codificam para uma histona H3 y para o ARNr 18S, não apresentam variação nos seus níveis de expressão por efeito da inoculação, sugerindo que podem ser usados como genes de referencia em estudos de transcrição nesta interação planta-patógeno.
  • Determination of the content of ursolic and oleanolic acid in the
           cuticular wax of fruits of different species of Rosaceae

    • Abstract: Ursolic acid (UA) and oleanolic acid (OA) are two widely distributed triterpenes in fruits, especially those belonging to Rosaceae family. These triterpene isomers are of great pharmacological interest due to their multiple bioactive properties. For this reason, the objective of this study was to determine the content of UA and OA extracted from the cuticular wax of five highly edible fruits (quince, loquat, pear, peach and apple) all belonging to the Rosaceae family. The acids were analyzed by high performance liquid chromatography. Both UA and OA are present in all these fruits, however, UA is in greater quantities.Resumen El ácido ursólico (AU) y el ácido oleanólico (AO) son dos triterpenos ampliamente distribuidos en los frutos, sobre todo en aquellos que pertenecen a la familia Rosaceae. Estos isómeros triterpénicos son de gran interés farmacológico por sus múltiples propiedades bioactivas. Por esta razón, el presente trabajo tuvo como objetivo determinar el contenido de AU y AO extraídos de la cera cuticular de cinco frutos bastante comestibles (membrillo, níspero, pera, durazno y manzana), todos ellos pertenecientes a la familia Rosaceae. El método empleado para analizar estos ácidos fue cromatografía líquida de alta eficiencia. De lo anterior, se concluyó que tanto el AU como el AO están presentes en todos los frutos mencionados, sin embargo, el AU se encuentra en mayores cantidades.Resumo Ácido ursólico (AU) e ácido oleanólico (AO) são dois triterpenos amplamente distribuídos em frutos, especialmente aqueles pertencentes à família Rosaceae, estes isómeros triterpénicos são de grande interesse farmacológico por suas múltiplas propriedades bioativas. Por esse motivo, o objetivo deste estudo foi determinar o conteúdo de AU e AO extraídos da cera cuticular de cinco frutos altamente comestíveis (marmelo, néspera, péra, pêssego e maçã) pertencentes à família Rosaceae. O método utilizado para esse fim foi a cromatografia líquida de alta eficiência. O resultado mostrou que AU e AO estão presentes em todas essas frutas, sendo a primeira a que está em maior quantidade.
  • Phenolic compounds and antioxidant activity of extracts from chirimoya
           (Annona cherimola Mill) leaf

    • Abstract: Resumen Después de la cosecha del fruto chirimoya, los árboles liberan enormes cantidades de hojas, las cuales son quemadas por los agricultores. Este trabajo muestra que las hojas pueden ser usadas para nuestro beneficio como antioxidante. Se determinaron los compuestos fenólicos (CF) y la actividad antioxidante (AA) de los extractos de la hoja seca de Annona cherimola Mill en etanol al 70% v/v, agua a 80 °C, y agua subcrítica (AS) a 110, 120 y 130 °C, siguiendo un diseño factorial con el programa Minitab. Los CF se cuantificaron con la metodología de Folin Ciocalteu y la AA con el 2,2-difenil-1-picrilhidrazilo (DPPH) y con el poder antioxidante reductor del hierro (FRAP). Los resultados indicaron que el tipo de solvente y el tiempo de extracción presentaron un efecto significativo en el contenido de CF y AA de los extractos. Se concluyó que el extracto de hoja de chirimoya es un potencial antioxidante. El extracto de AS a 130 °C presentó el mayor contenido de CF (5,6 g EAG/100 g de hoja seca) y el extracto etanólico presentó mayor AA (0,86 mg equivalente trolox/mg extracto seco; IC50=0,020 mg de extracto seco/mL de extracto de hoja seca y FRAP de 1710,14 μmol equivalente trolox /g de hoja seca) y los extractos obtenidos con AS a menor temperatura presentaron mayores valores de AA. After harvesting cherimoya fruit, the trees release huge amounts of leaves, which are burned by farmers. This work shows that the leaves can be used as a source of antioxidants. Total phenolic compounds (TPC) and antioxidant activity (AA) of extracts of the dry leaf of Annona cherimola Mill in 70% v/v ethanol, water at 80 °C, subcritical water (SW) at 110 °C, 120 °C and 130 °C were determined, following a factorial design with the Minitab program. The TPC was quantified with the Folin Ciocalteu methodology, and the AA with 2,2-diphenyl-1-picrilhidrazil (DPPH) and Ferric Reducing Antioxidant Power (FRAP). Results indicate that the type of solvent and the extraction time had a significant effect on the TPC and AA of the extracts. Extracts of cherimoya leaves were found to be a potential antioxidant. The extract of SW at 130 °C presented the highest content of TPC (5.6 g EAG/100 g dry leaves) and the ethanolic extract had the highest AA (0.86 mg trolox equivalent/mg dry extract, IC50 = 0.020 mg dry extract/mL extract of dry leaves and FRAP of 1710.14 μmol ET/g dry leaves) and the extracts obtained with SW at a lower temperature presented a higher AA value.Resumo Depois da colheita da fruta Cherimoya, as árvores liberam grandes quantidades de folhas, que são queimadas pelos agricultores. Este trabalho mostra que as folhas podem ser usadas para nosso benefício como um antioxidante. Compostos fenólicos (FC) e a actividade antioxidante (AA) de extractos de folha seca Annona cherimola Mill em etanol a 70% v/v água a 80 °C, água subcrítica (AS) 110, 120, 130 °C, foram determinados seguindo um planejamento fatorial com o programa Minitab. Os FC foram quantificados com a metodologia Folin Ciocalteu; e a capacidade antioxidante (AA) com 2,2-difenil-1-picrilhidrazil (DPPH) e poder antioxidante redutor de ferro (FRAP). Os resultados indicaram que o tipo de solvente e o tempo de extração tiveram um efeito significativo no conteúdo deCFeAA dos extratos. Conclui-se que o extracto de folha de cherimoya é um potencial antioxidante, o extracto de AS 130 °C tinha o maior conteúdo de CF (5,6 g EAG/100 g folha seca) e o extracto etanólico mostraram maior AA (0,86 mg equivalente Trolox/mg extrato seco, IC50 = 0,020 mg extrato seco/mL extracto de folha seca e FRAP de 1710,14 μmol ET/g folha seca). Os extratos obtido com AS a uma temperatura mais baixa apresentaram um maior valor de AA.
  • Characterization and stability of an extract rich in anthocyanins from
           passion purple fruit peel

    • Abstract: Resumen La gulupa es una fruta originaria de la región amazónica, cuyo epicarpio es un subproducto con alto potencial en antioxidantes como las antocianinas. Por lo anterior, los objetivos de este estudio fueron realizar una extracción por solvente, a partir del epicarpio, para obtener un extracto rico en antocianinas; caracterizar su capacidad antioxidante y realizar la cinética de degradación de antocianinas monoméricas durante el almacenamiento a tres temperaturas (-14 ± 2 °C, 5 ± 1 °C y 21 ± 0,7 °C). En consecuencia, se obtuvo un extracto con un contenido de antocianinas de 165 ±9 mg cianidina-3-O-glucosido/L. La capacidad antioxidante fue de 464 ± 19 y 366 ± 7 μmol Trolox/100 g de extracto, según los ensayos FRAP y DPPH respectivamente, y un contenido de vitamina C de 2,07 ± 0,04 mg ácido ascórbico/100 g de extracto. La cinética de degradación se definió por el orden uno con las siguientes constantes: 2, 1·10-3, 8, 6·10-3 y 2,7·10-2 días-1 para -14 ± 2 °C, 5 ± 1 °C y 21 ± 0,7 °C respectivamente, generando una energía de activación de 46, 0·103 J/mo'l. Por consiguiente, se concluyó que es posible obtener, a partir del epicarpio de gulupa, extractos ricos en compuestos de alto valor como las antocianinas, los cuales son afectados por la temperatura de almacenamiento, siendo este un factor para considerar durante su aplicación en matrices alimentarias. Purple passion fruit is a fruit from the Amazon region whose epicarp is a by-product with high potential as a source of anthocyanins. The objective of this investigation was to do a solvent extraction from the epicarp to obtain an extract rich in anthocyanins, and then, to characterize its antioxidant capacity, and evaluate the anthocyanin kinetic degradation during storage at three temperatures (-14 ± 2 °C, 5 ± 1 °C and 21 ± 0,7 °C). In consequence, an extract was obtained with an anthocyanin content of 165 ± 9 mg cyanidin-3-O-glucoside/L, an antioxidant capacity of 464 ± 19 and 366 ± 7 μmol Trolox/100 g extract according to FRAP and DPPH assays respectively, and a vitamin C content of 2.07 ± 0.04 mg ascorbic acid/100 g extract. The degradation kinetics was defined by order one with the following degradation constants: 2,1·10-3, 8,6·10-3 and 2,7·10-2 days-1 for -14 ± 2 °C, 5 ± 1 °C and 21 ± 0,7 °C, respectively, which corresponds to an activation energy of 46.0·10-3 J/mol. Therefore, it is concluded that is possible to obtain, from purple passion fruit epicarp, high-value compounds extract rich, such as anthocyanin, that is affected by storage temperature, which is an important factor during its use in food matrices.Resumo O maracujá roxo é uma fruta nativa da região amazónica cujo epicarpo é um subproduto com alto potencial em antioxidantes como as antocianinas. Por conseguinte, o objectivo deste estudo foi a extracção por solventes a partir de epicarpo para se obter um extracto rico em antocianinas, caracterizar a sua capacidade antioxidante e executar a cinética de degradação de antocianinas monoméricas durante o armazenamento a três temperaturas (-14 ± 2 °C, 5 ± 1 °C e 21 ± 0,7 °C). Portanto, obteve-se um extracto contendo antocianina 165 ± 9 mg de cianidina-3-glucósido ou/L, a capacidade antioxidante de 464 ± 19 e 366 ± 7 micromol Trolox/100 g de extrato de acordo com o ensaio de FRAP e DPPH, e vitamina C de 2,07 ± 0,04 mg de ácido ascórbico/100 g de extrato. A cinética de degradação foi definida por ordem um com as seguintes constantes: 2,1·10-3, 8,6·10-3 e 2,7·10-2 dias-1 para -14 ± 2 °C, 5 ± 1 °C e 21 ± 0,7 °C respectivamente, gerando uma energia de ativação de 46,0·103 J/mol. Portanto, conclui-se que é possível obter, a partir de gulupa epicarpo, extrai rico em compostos de alto valor, tais como as antocianinas, as quais são afectadas por temperatura de armazenamento, sendo este um factor para ter em conta a sua aplicação em matrizes alimentares.
  • Synthesisandcharacterization of nanocompounds Fe3O4/Ag: its effect against
           Enterobacter aerogenes and Enterococcus faecaiis

    • Abstract: Resumen En el presente trabajo, se reporta la síntesis y caracterización de nanopartículas magnéticas de magnetita/plata (Fe3O4/Ag) para el estudio de sus propiedades antibacterianas frente a las bacterias Enterobacter aerogenes (Gram-negativa) y Enterococcus faecaiis (Gram-positiva). Las nanopartículas magnéticas de magnetita (MNPs) se sintetizaron por el método de solgel, usando bromuro de cetiltrimetilamonio (CTAB) como surfactante. Posteriormente, en la dispersión coloidal de magnetita, se llevó a cabo la reducción química in situ de iones de plata, usando glucosa como agente reductor y polivinilpirrolidona (PVP) como agente dispersante, para obtener un nanocompuesto magnético Fe3O4/Ag. El análisis morfológico y espectroscópico de las nanopartículas de Fe3O4 y del nanocompuesto de Fe3O4/Ag fue realizado mediante la espectroscopia infrarroja con transformada de Fourier (FTIR), Raman, y Mössbauer (MS), además de la técnica de difracción de rayos X (DRX), la microscopía electrónica de barrido (SEM) y espectroscopia de energía dispersiva de rayos X (EDS). Las nanopartículas de Fe3O4 resultaron esféricas con un diámetro medio de 10 nm y el nanocompuesto de Fe3O4/Ag con un tamaño medio de 28 nm, el test antibacteriano indicó que el uso del nanocompuesto de Fe3O4/Ag a una concentración de 5 mg'mL-1 permite una inhibición total del crecimiento de los microorganismos estudiados a partir de una concentración inicial 108 bacterias mL-1. In the present study, we report the synthesis and characterization of magnetite/silver magnetic nanoparticles (Fe3O4/Ag) and the study of their antibacterial properties against the bacteria Enterobacter aerogenes (Gramnegative) and Enterococcus faecaiis (Grampositive). Magnetite magnetic nanoparticles (MNPs) were prepared by a sol-gel method using cetyltrimethylammonium bromide (CTAB), as a surfactant, followed by in-situ chemical reduction of silver ions by glucose, and polyvinylpyrrolidone (PVP), as a dispersive agent, to obtain the antibacterial nanocomposite of Fe3O4/Ag. Morphological and spectroscopic studies of magnetite nanoparticles and nanocomposite were carried out using the Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Mössbauer spectroscopy (MS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Spherical Fe3O4 MNPs showed an average diameter of 10 nm and the average size for nanocomposite was 28 nm. The antibacterial test indicated that the use of the nanocomposite of Fe3O4/Ag at a concentration of 5 mg'mL-1 allowed a total inhibition of the growth of the microorganisms studied from an initial concentration of 108 bacteria mL-1.Resumo No presente trabalho, relatamos a síntese e caracterização de nanopartículas magnéticas de magnetita/prata (Fe3O4/Ag) e o estudo de suas propriedades antibacterianas contra as bactérias Enterobacter aerogenes (Gram-negativo) e Enterococcus faecaiis (Gram-positiva). Nanopartículas magnéticas de magnetita (MNPs) foram sintetizadas pelo método solgel usando o bromuro de cetiltrimetilamonio (CTAB) como surfactante. Posteriormente, na dispersão coloidal de magnetita, a redução química in situ dos íons de prata foi realizada utilizando-se glicose, como agente redutor, e polivinilpirrolidona (PVP), como agente dispersante, para obter um nanocompósito magnético Fe3O4/Ag. A análise morfológica e espectroscópica das nanopartículas de Fe3O4 e do nanocompuesto de Fe3O4/Ag conduziu-se através da espectroscopia infravermelha com transformada de Fourier (FTIR), Raman, e Mössbauer (MS), además da técnica de raio X da deformação (DRX), a microscopia eletrônica de barrido (SEM) e a espectroscopia de energia dispersiva de raios X (EDS). As nanopartículas de Fe O têm formas esféricas com um diâmetro médio de 10 nm e o nanocompósito de Fe3O4/Ag com um tamanho promédio de 28 nm. O teste antibacteriano indicou que o uso do nanocompósito Fe3O4/Ag na concentração de 5 mg'mL-1 permitiu inibir totalmente o crescimento dos microrganismos estudados a partir de uma concentração inicial de 108 bactérias mL-1.
  • Theoretical evaluation of the electronic and structural properties that
           affect the electrical conductivity in furan-thiophene copolymers

    • Abstract: Resumen Desde el punto de vista científico y tecnológico ha habido un gran interés en el uso de monosustituyentes de furano y tiofeno como polímeros conductores, debido a sus múltiples aplicaciones como OLED, amplificadores ópticos, nanotecnología, entre otros. Por ello, el propósito de este trabajo fue estudiar los aspectos teóricos que afectan las propiedades electroconductoras de este tipo de moléculas. Se determinaron teóricamente los aspectos estructurales y electrónicos que influyeron en la conductividad de copolímeros de furano-tiofeno monosustituidos, al utilizar grupos carboxilos, metilos, hidroxilos, ciano y fluoruros como sustituyentes en el carbono C3 y C10 de cada heterociclo. La diferencia de energía entre el LUMO y el HOMO (band gap, Eg) y el potencial de ionización (PI) fue calculada a partir de las geometrías optimizadas en DFT para el estado neutro, anión y catión. Los PI y la Eg de los copolímeros fueron obtenidos mediante la extrapolación de los valores del oligómero a (1/N) y de una cadena de longitud infinita (1/N=0), obteniéndose una correlación lineal (R=0,99), la cual se mantiene a lo largo de todos los modelos de ajuste de cada copolímero analizado en el estudio. There has been great scientific and technological interest in the use of mono-substituents of furan and thiophene as conducting polymers due to their multiple applications such as OLED, optical amplifiers and nanotechnology, among others. For this, the purpose of this work was to study the theoretical aspects that affect the electroconductive properties of this type of molecules. The structural and electronic properties that influence the conductivity of mono substituted-furan-thiophene copolymers were determined theoretically. The effect of using carboxyl, methyl, hydroxyl, cyano, and fluoride groups as substituents on the carbon C3 and C10 of each heterocycle was observed. The energy difference between the LUMO and the HOMO (band gap, Eg) and the ionization potential (IP) were calculated from the geometries optimized in DFT for the neutral, anion and cation state. The PI and Eg of the copolymers were obtained by extrapolating the values of the oligomer a (1/N) and a chain of infinite length (1/N=0) for which a linear correlation was obtained (R=0.99). This correlation is maintained throughout all the adjustment models of each copolymer analyzed in the study.Resumo Existe muito interesse os termos científicos e tecnológicos em utilizar substituintes mono-substituídos furano e tiofeno como polímeros condutores devido às suas múltiplas aplicações, tais como OLED, amplificadores ópticos e nanotecnologia, entre outros. O objetivo deste trabalho foi estudar os aspectos teóricos que afetam as propriedades eletrocondutoras deste tipo de moléculas. Neste contribuição os aspectos estruturais e electrónicas que influenciam a condutividade de copolímeros furano-tiofeno substituos mono teoricamente determinada observando o efeito do uso de grupos carboxilo, metilo, hidroxilo, ciano e fluoretos como substituintes em C3 e C10 de carbono de cada heterociclo. A diferença de energia entre o LUMO e o HOMO (intervalo de banda, Eg) e o potencial de ionização (IP) foram calculadas a partir das geometrias optimizadas de DFT para o estado neutro, anião e catião. O PI e o Eg dos copolímeros foram obtidos por extrapolação dos valores do oligómero (1/N) e extrapolando para uma cadeia de comprimento infinito (1/ N=0) para os quais uma correlação linear foi obtida (R=0,99), que é mantido ao longo de todos os modelos de ajuste de cada copolímero analisados no estudo.
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327
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