741 research outputs found

    Analytical approach to directed sandpile models on the Apollonian network

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    We investigate a set of directed sandpile models on the Apollonian network, which are inspired on the work by Dhar and Ramaswamy (PRL \textbf{63}, 1659 (1989)) for Euclidian lattices. They are characterized by a single parameter qq, that restricts the number of neighbors receiving grains from a toppling node. Due to the geometry of the network, two and three point correlation functions are amenable to exact treatment, leading to analytical results for the avalanche distributions in the limit of an infinite system, for q=1,2q=1,2. The exact recurrence expressions for the correlation functions are numerically iterated to obtain results for finite size systems, when larger values of qq are considered. Finally, a detailed description of the local flux properties is provided by a multifractal scaling analysis.Comment: 7 pages in two-column format, 10 illustrations, 5 figure

    Secondary Metabolites

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    Plants are the main source for obtaining secondary metabolites that are used in the pharmaceutical, cosmetic and food industries. In nature, the performance of bioactive compounds is affected by biotic and abiotic factors, an alternative to overcome this adversity is in vitro plant cultures and particularly plant cell culture that has multiple advantages, highlighting the possibility of controlling variables to increase the content. of compounds of interest. The objective of this research was to determine and optimize the effect of some elicitors on the production of secondary flavonoid metabolites in suspension cell cultures of Thevetia peruviana on a shake flask scale. The experimental part was performed from cell cultures in suspension cells of T. peruviana maintained by the Bioconversion Laboratory of the Universidad Nacional de Colombia, sede Medellin. Firstly, methyl jasmonate (MeJa) 3 µM and salicylic acid (SA) 300 µM were added to two los of cell cultures, that circumstantially they differed in their time suspension state lot 1 (9 months) and lot 2 (3 months). Secondly, certain were evaluated, in order to be optimized; the operational parameters cosidered were: day of addition, concentration and hours of harvest. Finally, the combined effect of MeJa (0.3 µM) and SA (100 µM) was determined in different proportions, the day of elicitation and the hours of harvest were constant. Flavonoid content was quantified by UV-vis spectrophotometry usinfg the AlCl3 complexation method and was evaluated at extracellular and intracellular level. In the first part, at intracellular level, SA generated 14.6 % and 9.56 % more flavonoid content than MeJa in lots 1 and 2, respectively. In the second part, 4.14 mg EQ/g DW were generated with MeJa 0.3 µM, elicitation day 5 and harvest at 90 h; 3.75 mg EQ/g DW were generated with 100 µM SA, elicitation day 0 and harvests at 96 h. In the third part, 4.62 mg EQ / g DW were generated with the combination of MeJa (0.3 µM) – SA (100 µM) in a ratio of 20-80, elicitation on day 0 and harvest at 96 h. Eliciting cell cultures of Thevetia peruviana with MeJa and SA under optimal conditions of concentration, day of addition and hours of harvest increased the content of flavonoid compounds. The results obtained could serve as a basis for the development of investigations at the bioreactor scale.Las plantas son la principal fuente para la obtención de metabolitos secundarios que se usan en la industria farmacéutica, cosmética y alimentaria. En la naturaleza el rendimiento de compuestos bioactivos se ve afectado por factores bióticos y abióticos, una alternativa para superar esta adversidad son los cultivos vegetales in vitro y particularmente el cultivo de células en suspensión que presenta múltiples ventajas destacándose la posibilidad de controlar variables para aumentar el contenido de compuestos de interés. El objetivo del presente trabajo de investigación fue determinar y optimizar el efecto de algunos elicitores sobre la producción de metabolitos secundarios tipo flavonoides en cultivos de células en suspensión de Thevetia peruviana a escala de matraz agitado. La parte experimental se realizó a partir de cultivos de células en células en suspensión de T. peruviana que mantenía el laboratorio de bioconversiones de la Universidad Nacional de Colombia sede Medellín. Primeramente, metil jasmonato (MeJa) 3 μM y ácido salicílico (AS) 300 μM se adicionaron a dos lotes de cultivos de células; que circunstancialmente diferían en su tiempo en estado de suspensión lote 1 (9 meses) y lote 2 (3 meses). Segundamente, determinadas condiciones fueron evaluadas, con el fin de ser optimizadas; los parámetros operacionales que se consideraron fueron: día de adición, concentración y las horas de cosecha. Por último, el efecto combinado de MeJa (0,3 μM) – AS (100 μM) se determinó en diferentes proporciones, el día de elicitación y las horas de cosecha fueron constantes. El contenido de flavonoides se cuantificó por espectrofotometría UV – vis por el método de complejación de AlCl3 y se evaluaron a nivel extracelular e intracelular. En la primera parte, a nivel intracelular AS generaron 14,6 % y 9,56 % más contenido de flavonoides que MeJa en lotes 1 y 2, respectivamente. En la segunda parte, 4,14 mg EQ/g MS fueron generados con MeJa 0,3 μM, elicitación día 5 y cosecha a 90 h; por otro lado, 3,75 mg EQ/g MS fueron generados con AS 100 μM, elicitación día 0 y cosecha a 96 h. En la tercera parte, 4,62 mg EQ/g MS fueron generados con la combinación de MeJa (0,3 μM) – AS (100 μM) en proporción 20 – 80, elicitación el día 0 y cosecha a las 96 h. Elicitar cultivos celulares de Thevetia peruviana con MeJa y AS en condiciones óptimas de concentración, día de adición y horas de cosecha incrementaron el contenido de compuestos flavonoides. Los resultados obtenidos podrían servir como base para el desarrollo de investigaciones a escala de biorreactor.Maestrí

    Infraspecific variability in the essential oil composition of Lychnophora ericoides

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    Variations in the composition of the leaf essential oils of wild Lychnophora ericoides, with and without scent, which were grown in three sampling sites, were examined by GC-MS. Results were submitted to principal component and cluster analysis which allowed for two groups of essential oils to be distinguished with regard to scent: cluster I with specimens exhibiting an aromatic scent and containing a high percentage of α-bisabolol (34 ± 23%) and o-cymene (8.4 ± 6.9%); cluster II with specimens without any scent and characterised by a high percentage of caryophyllene oxide (11 ± 9%) and δ-elemene (5.7 ± 6.9%). The two types of oil coexist in all the populations under study, although patterns of aromatic samples deriving from Caldas Novas' State Park reveal chemical differences in relation to the samples from Brasília's National Park and Santo Antônio do Descoberto. Such chemical variations clearly suggest, apart from a geographical influence, genetic differences between individuals in the populations. The high content of α-bisabolol supports the folk medicinal use of arnica as anti-inflammatory

    Efeitos de doses de fósforo em mamoneira (Ricinus communis L.), cultivar 'Campinas'

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    With the aim to verify as phosphorus can increase castor bean yield, an experiment was conducted, using the "Campinas" cultivar. It was laid out during season of 1971-1972 and the experimental design was in randomized brodkss, with five replications and six rates of phosphorus, 0 - 40 - 80 - 120 - 160 - 200 kg of P2O5/ha. According to the data, the following conclusions can be drawn. There was an increase of the seed production of 320% when the data of the treatments with prosphorus were compared with that without phosphorus. This is due to the fact that phosphorus increased the number of fruits by raceme and by plot, the seed weight, and decreased the percentage of hulls in the fruits. Among the racemes, the first one gave better response to phosphorus. Fertilizer phosphorus application increased the phosphorus content of the seed and showed a tendency to diminish the nitrogen content of the hulls. The oil seed content was not affected by the phosphorus addition in soil.Nos últimos trabalhos de adubação, feitos no Estado de São Paulo, com mamoneira, tem-se observado que o fósforo é o fator limitante na produção de sementes. Para observar como o fósforo atua no crescimento, na produção e nos teores de óleo e de macronutrientes nos frutos, foi realizado um ensaio de campo, utilizando-se cultivar "Campinas" e as doses de 0-40-80-120-160 e 200 kg/ha de P2O5, num solo pobre, classificado como Latossolo Vermelho Escuro - fase arenosa. Em relação ao tratamento sem fósforo, o incremento médio observado na produção de sementes foi de 320,40%. Esses aumentos foram alcançados porque o fósforo contribuiu para aumentar o número de frutos, por cacho e por parcela, diminuir a porcentagem de casca no fruto e aumentar o peso de sementes por cacho. Dentre os cachos, os primários sempre reagiram melhor ao fósforo. Contribuiu também para elevar o teor do próprio fósforo nas sementes e uma tendência a diminuir o teor de nitrogênio nas cascas. O teor de óleo nas sementes não foi afetado pela adição de fósforo no solo

    Differential metabolic and biological profiles of Lychnophora ericoides mart. (Asteraceae) from different localities in the Brazilian "campos rupestres"

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    This paper reports HPLC-DAD-MS/MS and HPLC-ECD characterisation of secondary metabolite profiles of Lychnophora ericoides Mart. leaf extracts from different provenances and their cytotoxic and antioxidant properties. Leaf extracts from populations representing seven different locations were evaluated for antioxidant activity by the DPPH radical scavenging system and activity towards cellular growth in three tumor cell lines. The extracts were electrochemically analysed by HPLC-ECD and their main secondary metabolites were identified by HPLC-DAD-MS and HPLC-DAD-MS/MS. An amplified defensive secondary chemistry, together with maximal cytotoxic and antioxidant bioactivities, were found for plants collected at the interface between two types of forest. These findings furnish additional support for the hypothesis that plants occurring at the interface between two forests ecosystems might be stimulated to amplify their own production and storage of defensive secondary metabolites due to the greater number of environmental influences

    Acid-base titration of melanocortin peptides: evidence of Trp rotational conformer interconversion

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    Abstract: Tryptophan time-resolved fluorescence was used to monitor acid-base titration properties of ␣-melanocyte stimulating hormone (␣-MSH 2, 6

    Factors associated with thrombocytopenia in severe leptospirosis (Weil's disease)

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    OBJECTIVE: This study was conducted to investigate factors associated with thrombocytopenia in a large cohort of patients with leptospirosis in an endemic area. METHODS: This retrospective study included 374 consecutive patients with leptospirosis who were admitted to tertiary hospitals in Fortaleza, Brazil. All patients had a diagnosis of severe leptospirosis (Weil's disease). Acute kidney injury was defined according to the RIFLE criteria. Thrombocytopenia was defined as a platelet coun

    A biodiversidade terrestre e dulçaquícola dos arquipélagos da Madeira e das Selvagens

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    As ilhas atlânticas dos Açores, Madeira, Selvagens, Canárias e Cabo Verde constituem uma das regiões da Europa mais ricas em diversidade de fungos, plantas e animais. Desde 2004 que a inventariação detalhada da diversidade destas ilhas tem sido um dos principais objectivos dos projectos ATLÂNTICO e BIONATURA (incluídos no projecto EU INTERREG IIIB). Este livro é a mais recente contribuição destes projectos, apresentando uma lista de todos os fungos, flora e fauna terrestre conhecida, incluindo a dulçaquícola, para dois arquipélagos atlânticos (Madeira e Selvagens). A lista abrange o arquipélago da Madeira, constituído por duas ilhas de maiores dimensões (Madeira e Porto Santo) e três pequenas, cujo conjunto constitui as Desertas (Ilhéu Chão, Deserta Grande e Bugio), e ainda o arquipélago das Selvagens, formado por duas pequenas ilhas (Selvagem Grande e Selvagem Pequena) e um ilhéu (Ilhéu de Fora).ABSTRACT: The Azores, Madeira, Selvagens, Canary Islands and Cape Verde are among the richest regions in Fungi, plant and animal diversity in Europe. The main objectives of the EU INTERREG IIIB projects ATLÂNTICO and BIONATURA have been, since 2004, to carry out a detailed inventory of the terrestrial Fungi, Flora and Fauna of these archipelagos. This book, encompassing a checklist of all the known terrestrial and freshwater Fungi, Flora and Fauna of Madeira and Selvagens archipelagos is the latest contribution towards that goal. The geographic scope of this checklist includes the Madeira archipelago, composed of two large islands (Madeira and Porto Santo) and three small islands, which are globally named Desertas (Ilhéu Chão, Deserta Grande and Bugio), and the archipelago of Selvagens with two small islands (Selvagem Grande and Selvagem Pequena) and one islet (Ilhéu de Fora)
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