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Sample records for cymbopogon citratus dc

  1. Cellular Suspensions Establishment and Multiplication of Cymbopogon citratus (D.C Staff

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    Elisa Quiala

    2002-07-01

    Full Text Available Cellular suspensions settled down starting from callus of Cymbopogon citratus (D.C Stapf cultivated in semisolid medium, according to the methodology described for Freire (1998, for the cultivation of the cane of sugar and later on modified by Licea and Gómez (2000 for the cultivated callus of Cane Santa, with the objective of analyzing the effect of the cellular density on the cellular growth, being studied the behavior of the fresh mass, dry mass and the pH in three inocule densities (20, 40 and 60 gMF.l-1. The development of roots was evaluated in the cellular aggregated and it was also analyzed directly the influence of the explants on the callus formation cultivated directly in liquid medium, starting from cultivated plants in vitro. The biggest increment of fresh mass was obtained when 20 gMF.l-1 was used, the values of mass dry off they behaved in a similar way, being obtained the biggest rate of growth in this same treatment. The pH in the three densities of studied inocule, diminished during the first eight days and stayed stable starting from this moment. The alone presence of roots was appreciated only in the cellular aggregated cultivated without coconut water. The formation of callus directly in liquid medium took place in the region near to the meristematic area. Key words: coconut water, biomass production, lemon grass, root formation

  2. Study of the chemical composition of essential oils and floral waters of Cymbopogon citratus (DC.) Stapf (Poaceae) from Senegal

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    Diop, Serigne Mbacké; Guèye, Momar Talla; Ndiaye, Ibrahima; Diop, Michel Bakar; Ndiaye, El Hadji Barka; Thiam, Abdoulaye; Fauconnier, Marie-Laure; Lognay, Georges

    2017-01-01

    This work aimed to study the chemical composition of essential oils and floral waters of Cymbopogon citratus (DC.) Stapf (Poaceae) from Senegal. The plants were collected in two different localities, Dakar and Kaolack. The extracts were obtained by steam distillation from both fresh and dried plants and analyses carried out by GC/FID and GC/MS. Oils from Dakar were dominated by geranial which represented 46.0-43.9%, neral 31.8-31.0%, myrcene 10.8-11.7% and geraniol 2.7-4.2% in the fresh and d...

  3. Antifungal Activity of the Essential Oil of Cymbopogon citratus (DC Stapf. An in vitro study.

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    Naiana Braga da Silva

    2017-12-01

    Full Text Available Aim. To evaluate the antifungal potential of the essential oil of Cymbopogon citratus by determining the Minimum Inhibitory Concentration (MIC and the Minimum Fungicidal Concentration (MFC for Candida albicans (ATCC 90029, Candida albicans (CBS 562, Candida tropicalis (ATCC 705 and Candida tropicalis strains (CBS 94, as well as to analyze the possible mechanism of action of the oil through the addition of sorbitol to the culture medium. Methods. For the MIC determination, inocula were previously adjusted through spectrophotometry and 100μL were added to the wells of plates already containing the culture medium and 100μL of the serial dilutions of the oil, incubating them in aerobiosis for 24 hours, with subsequent staining by 1% TCT. For the MFC, 50μL of the supernatant from the MIC assay wells were dripped onto Petri dishes and incubated in aerobiosis for 24 hours. Tests were performed in triplicate and data analysed by descriptive statistics. Results. It was determined that the MIC for C. albicans was 125 μg/mL while MIC for C. tropicalis was 250 μg/mL, with the essential oil presenting fungicidal effect for both analyzed yeasts. Conclusion. The essential oil of Cymbopogon citratus does not act at the cellular wall level and demonstrated an antimicrobial effect on Candida albicans and Candida tropicalis, therefore acting as a fungicide.

  4. Antimicrobial activity of the essential oil of Cymbopogon citratus (DC Stapf. on Staphylococcus spp., Streptococcus mutans and Candida spp.

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    RBA Almeida

    2013-01-01

    Full Text Available Medicinal plants with fungicide action, antibacterial and anti-inflammatory effects are under investigation. The main purpose of this work was to evaluate the antimicrobial activity of the essential oil from Cymbopogon citratus (DC Stapf. on strains of Staphylococcus spp., Streptococcus mutans and Candida spp. with planktonic and biofilm growth. To study the micro-organisms in planktonic cells, the minimal inhibitory concentration (MIC and minimal bactericidal concentration (MBC were determined by using 9 clinical strains for each species and 1 ATCC (American Type Culture Collection from C. albicans, C. tropicalis, C. glabrata, S. aureus, S. epidermidis and S. mutans. In order to evaluate the effects of the essential oils on biofilms, strains of S. aureus (ATCC 6538, S. mutans (ATCC 35688 and C. albicans (ATCC 18804 were used. The biofilm was formed on acrylic resin discs with isolated micro-organisms or in associations. The number of colony-forming-units (CFU obtained in each biofilm (CFU/ml was submitted to Student's t statistical test. The results demonstrated that the essential oil of Cymbopogon citratus showed microbiostatic and microbicidal activity against all tested strains. The average CFU/ml for the biofilm of S. aureus, S. mutans and C. albicans, whether isolated or in association, was lower in the group treated with essential oil than in the control group.

  5. Evaluation of Antibacterial Activity of Aminoglycosides and Modulating the Essential Oil of Cymbopogon citratus (DC. Stapf

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    Saulo R. TINTINO

    2015-01-01

    Vários trabalhos vêm demonstrando a importância do estudo de produtos naturais como fonte alternativa para novos antimicrobianos ou que venham potencializar os já existentes. Neste contexto este trabalho teve como objetivo investigar a atividade antibacteriana e as possíveis interações entre o óleo essencial de Cymbopogon citratus combinados a aminoglicosídeos frente a linhagens padrões e multirresistentes de S. aureus, E. coli e de P. aeruginosa provenientes de isolados clínicos. Um ensaio de microdiluição foi realizado para verificar a atividade antibacteriana e as possíveis interacções entre o produto natural e os antibióticos, utilizando uma concentração sub-inibitória. Através dos resultados foi constatado a interferência sinérgica dos aminoglicosídeos quando associados com o óleo essencial em uma concentração de CIM/8, com redução das CIMs em até quatro pontos frente às linhagens de S. aureus 358, E. coli 27 e P. aeruginosa-143. Mas nenhuma atividade modificadora foi observada frente a P. aeruginosa 78 e P. aeruginosa 91. Através dos resultados pode-se concluir que o óleo essencial de Cymbopogon citratus pode ser uma fonte alternativa de produtos naturais com atividade antibacteriana. Vários trabalhos vêm demonstrando a importância do estudo de produtos naturais como fonte alternativa para novos antimicrobianos ou que venham potencializar os já existentes. Neste contexto este trabalho teve como objetivo investigar a atividade antibacteriana e as possíveis interações entre o óleo essencial de Cymbopogon citratus combinados a aminoglicosídeos frente a linhagens padrões e multirresistentes de S. aureus, E. coli e de P. aeruginosa provenientes de isolados clínicos. Um ensaio de microdiluição foi realizado para verificar a atividade antibacteriana e as possíveis interacções entre o produto natural e os antibióticos, utilizando uma concentração sub-inibitória. Através  dos resultados foi constatado a

  6. Evaluation of the Chemical Composition of Brazilian Commercial Cymbopogon citratus (D.C. Stapf Samples

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    Evandro de Castro Melo

    2008-08-01

    Full Text Available Abstract: The concentration and the chemical composition of the essential oils obtained from different samples of Cymbopogon citratus were evaluated. Among the 12 samples investigated (11 dried leaf samples and fresh plant leaves, seven presented essential oil concentrations within the threshold established by the Brazilian legislation. The moisture content was also determined and the majority of the samples presented humidity contents near 12%. The GC and GC/MS analyses of the essential oils led to identification of 22 compounds, with neral and geranial as the two major components. The total percentage of these two compounds varied within the investigated sample oils from 40.7% to 75.4%. In addition, a considerable variation in the chemical composition of the analyzed samples was observed. The process of grinding the leaves significantly decreased (by up to 68% the essential oil content, as well as the percentage of myrcene in the oils.

  7. Chemical composition and cardiovascular effects induced by the essential oil of Cymbopogon citratus DC. Stapf, Poaceae, in rats

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    Flávia V. Moreira

    2010-08-01

    Full Text Available Cymbopogon citratus DC. Stapf, Poaceae, is used in the folk medicine for hypertension treatment. This work investigated the chemical composition and cardiovascular effects in rats of C. citratus essential oil (EOCC. A phytochemical screening demonstrated the presence of eight constituents, being geranial the major compound (43.08%. In rats, EOCC (1, 5, 10, and 20 mg/kg, i.v. induced transient hypotension and bradycardia that were attenuated by atropine and sodium thiopental, but not by L-NAME or indomethacin. In rings of rat superior mesenteric artery pre-contracted with phenylephrine, EOCC (1 to 3000 µg/mL induced relaxation that was not affected after removal of the endothelium, after TEA or in rings pre-contracted with KCl (80 mM. Furthermore, EOCC (1000 µg/mL was not able to induce additional effect on maximal relaxation of nifedipine (10 µM. In conclusions, EOCC induces hypotension, possibly by reduction in vascular resistance caused by inhibition of the Ca2+ influx, and bradycardia probably due to an activation of cardiac muscarinic receptors.

  8. Free radical scavengers and antioxidants from Lemongrass (Cymbopogon citratus (DC.) Stapf.).

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    Cheel, José; Theoduloz, Cristina; Rodríguez, Jaime; Schmeda-Hirschmann, Guillermo

    2005-04-06

    Methanol, MeOH/water extracts, infusion, and decoction of Cymbopogon citratus were assessed for free radical scavenging effects measured by the bleaching of the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical, scavenging of the superoxide anion, and inhibition of the enzyme xanthine oxidase (XO) and lipid peroxidation in human erythrocytes. The extracts presented effect in the DPPH and superoxide anion assay, with values ranging between 40 and 68% and 15-32% at 33 and 50 microg/mL, respectively, inhibited lipid peroxidation in erythrocytes by 19-71% at 500 microg/mL and were inactive toward the XO at 50 microg/mL. Isoorientin, isoscoparin, swertiajaponin, isoorientin 2' '-O-rhamnoside, orientin, chlorogenic acid, and caffeic acid were isolated and identified by spectroscopic methods. Isoorientin and orientin presented similar activities toward the DPPH (IC(50): 9-10 microM) and inhibited lipid peroxidation by 70% at 100 microg/mL. Caffeic and chlorogenic acid were active superoxide anion scavengers with IC(50) values of 68.8 and 54.2 microM, respectively, and a strong effect toward DPPH. Caffeic acid inhibited lipid peroxidation by 85% at 100 microg/mL.

  9. Controle da ferrugem das folhas do capim-limão [Cymbopogon citratus (DC: Stapf] com produtos naturais Rust control in leaves of lemongrass [Cymbopogon citratus (DC: Stapf] by using natural products

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    E.R. Lorenzetti

    2012-01-01

    Full Text Available Cymbopogon citratus (DC. Stapf é uma planta medicinal pertencente a família Poaceae, perene, importante para a indústria farmacêutica e alimentícia devido ao óleo essencial que produz. Um problema limitante para a produção comercial é a ferrugem, doença cujo agente etiológico é o fungo Puccinia nakanishikii Dietel. O presente trabalho objetivou avaliar a ação de produtos naturais no controle da doença in vitro e in vivo. Para os testes in vitro, empregaram-se os seguintes produtos sobre a germinação de esporos do patógeno: óleos essenciais de eucalipto, palma-rosa, cravo-da-índia, menta, limão, citronela e mil-folhas; extrato pirolenhoso de eucalipto e mentol cristalizado, em diferentes concentrações. Para os testes de campo foram selecionados quatro produtos, o óleo de citronela e de eucalipto, o extrato pirolenhoso, e o mentol. In vitro, todos os agentes mostraram-se promissores no controle do patógeno. Quando em condições in vivo, sob alta severidade da doença no ato da avaliação, os produtos testados foram capazes de reduzir a severidade da doença em comparação com a testemunha. O controle da doença com os agentes naturais variou de 38% (extrato pirolenhoso a 61%(óleo essencial de eucalipto.Cymbopogon citratus (DC. Stapf is a medicinal plant that belongs to the Poaceae family; it is perennial and important for the pharmaceutical and food industry due to the essential oil it produces. A limiting problem for commercial production is rust, a disease that has as etiological agent the fungus Puccinia nakanishikii Dietel. The present study aimed to evaluate the action of natural products on the disease control, in vitro and in vivo. For the in vitro tests, the following products were employed on the germination of the pathogen spores: essential oils from eucalyptus, palmarosa, clove, peppermint, lemon, citronella and yarrow, pyroligneous extract from eucalyptus, and crystallized menthol, at different

  10. Efecto anti-Trypanosoma cruzi del aceite esencial de Cymbopogon citratus (DC Stapf (hierba luisa en ratones Balb/c

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    Juan Rojas

    2012-01-01

    Full Text Available Objetivo: Determinar la actividad anti-Trypanosoma cruzi in vivo del aceite esencial de Cymbopogon citratus en ratones Balb/c. Diseño: Estudio experimental, prospectivo. Institución: Instituto de Investigaciones Clínicas e Instituto de Medicina Tropical de la Facultad de Medicina de la Universidad Nacional Mayor de San Marcos, Lima, Perú. Material biológico: Aceite esencial de Cymbopogon citratus; ratones albinos Balb/c. Intervenciones: Los animales fueron asignados aleatoriamente a seis grupos de 15 ratones cada uno: infectados y no tratados (G1, infectados y tratados con benznidazol 100 mg/kg (G2, infectados y tratados con aceite esencial de Cymbopogon citratus 100 mg/kg y 250 mg/kg (G3 y G4, respectivamente, no infectados y no tratados (G5, y no infectados y tratados con 250 mg de Cymbopogon citratus (G6. La infección con T. cruzi se realizó con 10(4 trypomastigotes sanguíneos y el tratamiento empezó en el 8º día post infección (dpi hasta el 28° dpi. La parasitemia se determinó con microscopia óptica cada dos días en 5 µL de sangre de la cola. En el 14°, 21° y 28° dpi, cinco animales de cada grupo fueron sacrificados y se removió el corazón para estudio histopatológico. Principales medidas de resultados: Parasitemia, número de nidos de amastigotes e infiltrados inflamatorios. Resultados: El aceite esencial de Cymbopogon citratus 250 mg/kg/día produjo una reducción significativa en el pico de parasitemia desde 113,92 ± 25,66 hasta 74,60 ± 12,37 tripomastigotes/mL (p < 0,05. Con 100 mg/kg/día se produjo una reducción hasta 77,40 ± 14,93 tripomastigotes/ mL (p < 0,05. También redujo el número de amastigotes y de infiltrados inflamatorios en el corazón. Conclusiones: El aceite esencial de Cymbopogon citratus tuvo efecto anti-Trypanosoma cruzi en ratones Balb/c en lo referente a la disminución de la parasitemia, el número de nidos de amastigotes y los resultados inflamatorios.

  11. Sugarcane Molasse and Whey as Additives in the Silage of Lemongrass (Cymbopogon citratus [DC.] Stapf) Leaves Melaza de Caña de Azúcar y Suero de Leche como Aditivos en el Ensilaje de Hojas de Zacate de Limón (Cymbopogon citratus [DC.] Stapf)

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    Lucía María Cristina Ventura-Canseco; José Alfredo Mendoza Nunez; Miguel Abud-Archila; Maria Ángela Oliva-Llaven; Luc Dendooven; Federico A. Gutiérrez-Miceli

    2012-01-01

    After extraction of essential oil from lemongrass (Cymbopogon citratus [DC.] Stapf) leaves by steam distillation (heat treatment), large amounts of organic wastes are obtained. This by-product could easily be used as animal feed. The potential of sugarcane molasse and whey as additives to ensile lemongrass leaves was investigated. The vegetative material was obtained after essential oils were extracted from lemongrass leaves with steam distillation. Lemongrass leaves were chopped, mixed with ...

  12. Calagem e adubação fosfatada favorecem o crescimento do capim-limão, Cymbopogon citratus (DC Stapf Liming and phosphate fertilization promote lemongrass, Cymbopogon citratus (DC Stapf., growth

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    C.V.T. Amarante

    2012-01-01

    Full Text Available O capim-limão, Cymbopogon citratus (DC Stapf., é uma planta utilizada para fins medicinais e aromáticos, porém pouco se conhece sobre as exigências nutricionais. O objetivo do presente trabalho foi avaliar os efeitos da elevação do pH do solo e da adubação com fósforo (P na disponibilidade de nutrientes e no crescimento inicial do capim-limão. O experimento foi conduzido em Lages, SC, de abril a dezembro de 2008, em casa de vegetação. Foi utilizado um esquema fatorial, incluindo quatro níveis de pH (4,1; 5,5; 6,0 e 6,5 e três doses de P (0, 50 e 100 mg kg-1 de solo, com quatro repetições (correspondendo a um vaso com duas plantas. A correção do pH aumentou o Ca e Mg e diminuiu o Al, Mn, Fe, Cu e Zn no solo. A aplicação de 100 mg kg-1 de P elevou em mais de 250% a concentração deste nutriente no solo, independente do pH. A aplicação de P e, principalmente, a elevação do pH do solo incrementaram todos os atributos avaliados nas plantas de capim limão (massa seca da parte aérea e do sistema radicular, número de folhas e altura de plantas, sendo que a interação entre pH e dose de P somente foi significativa para o número de folhas. O maior crescimento das plantas ocorreu no tratamento com pH 6,5, associado à adição de 100 mg kg-1 de P.Lemongrass, Cymbopogon citratus (DC Stapf., is a plant with medicinal and aromatic uses. However, little is known about its nutrition requirements. This work was carried out to investigate the effects of pH and phosphorus levels on nutrients availability and the initial growth of lemongrass. The experiment was carried out in Lages (SC, Brazil from April tol December 2008, in greenhouse conditions. The experiment followed a factorial design, with four levels of pH (4.1, 5.5, 6.0, and 6.5, three doses of phosphorus (0, 50, and 100 mg kg-1 of soil, and four replicates (each replicate corresponding to a pot with two plants. The correction of pH increased Ca and Mg, and reduced Al, Mn, Fe

  13. Efecto del aceite esencial de Cymbopogon citratus (DC.) stapf “hierba luisa” en los niveles de ansiedad de estudiantes de educación secundaria

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    Soto Vásquez, Marilú Roxana; Universidad Nacional de Trujillo; Alvarado García, Paúl Alan Arkin; Rosales Cerquin, Luis Enrique; Cerna Castillo, José

    2017-01-01

    El objetivo de la investigación fué evaluar el efecto del aceite esencial de Cymbopogon citratus (DC.) Stapf “hierba luisa” en los niveles de ansiedad de estudiantes del quinto grado de educación secundaria de una institución educativa pública. Se realizó un estudio cuasiexperimental, pretest y postest, con una muestra de 54 alumnos, divididos en un grupo experimental tratado con aromaterapia del aceite esencial estudiado, vía inhalatoria, y un grupo control, al cual no se le aplicó ningún es...

  14. Inhibitory activity of Syzygium aromaticum and Cymbopogon citratus (DC. Stapf. essential oils against Listeria monocytogenes inoculated in bovine ground meat

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    Thales Leandro Coutinho de Oliveira

    2013-01-01

    Full Text Available This research evaluated the antimicrobial effect of the clove (Syzygium aromaticum and lemongrass (Cymbopogon citratus (DC. Stapf. essential oils (EOs against Listeria monocytogenes ATCC 19117 growth added to bovine ground meat stored under refrigeration (5 ± 2 °C for three days. The EOs, extracted by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS, were tested in vitro using an agar well diffusion methodology for determination of Minimum Inhibitory Concentration (MIC. The MIC concentrations for both essential oils on culture tested of L. monocytogenes were 1.56%. The EOs concentrations applied in contaminated ground beef were 1.56, 3.125 and 6.25% (w/v based on MIC levels and possible activity reductions by food constituents. The bacteria populations were significantly reduced (p < 0.05 after one day of storage in ground meat samples treated with clove and lemongrass EOs at concentrations of 1.56%. There were no significant counts of L. monocytogenes in samples at the other concentrations of the two oils applied after the second day of storage. The sensory acceptability evaluation of the bovine ground meat samples treated with EOs showed that the addition at concentrations higher than 1.56% promote undesirable alterations of taste, odor and characteristic color. The application of EOs at low concentrations in food products can be used in combination with other preservation methods, such as refrigeration, to control pathogens and spoilage bacteria during shelf-life; which goes according to current market trends, where consumers are requesting natural products.

  15. Inhibitory activity of Syzygium aromaticum and Cymbopogon citratus (DC.) Stapf. essential oils against Listeria monocytogenes inoculated in bovine ground meat.

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    de Oliveira, Thales Leandro Coutinho; das Graças Cardoso, Maria; de Araújo Soares, Rodrigo; Ramos, Eduardo Mendes; Piccoli, Roberta Hilsdorf; Tebaldi, Victor Maximiliano Reis

    2013-01-01

    This research evaluated the antimicrobial effect of the clove (Syzygium aromaticum) and lemongrass (Cymbopogon citratus (DC.) Stapf.) essential oils (EOs) against Listeria monocytogenes ATCC 19117 growth added to bovine ground meat stored under refrigeration (5 ± 2 °C) for three days. The EOs, extracted by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS), were tested in vitro using an agar well diffusion methodology for determination of Minimum Inhibitory Concentration (MIC). The MIC concentrations for both essential oils on culture tested of L. monocytogenes were 1.56%. The EOs concentrations applied in contaminated ground beef were 1.56, 3.125 and 6.25% (w/v) based on MIC levels and possible activity reductions by food constituents. The bacteria populations were significantly reduced (p ≤ 0.05) after one day of storage in ground meat samples treated with clove and lemongrass EOs at concentrations of 1.56%. There were no significant counts of L. monocytogenes in samples at the other concentrations of the two oils applied after the second day of storage. The sensory acceptability evaluation of the bovine ground meat samples treated with EOs showed that the addition at concentrations higher than 1.56% promote undesirable alterations of taste, odor and characteristic color. The application of EOs at low concentrations in food products can be used in combination with other preservation methods, such as refrigeration, to control pathogens and spoilage bacteria during shelf-life; which goes according to current market trends, where consumers are requesting natural products.

  16. Modelagem matemática e parâmetros qualitativos da secagem de folhas de capim-limão [Cymbopogon citratus (DC. Stapf] Mathematical modeling and quality parameters of lemon grass [Cymbopogon citratus (DC. Stapf] leaf drying

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    A.P. Martinazzo

    2010-12-01

    Full Text Available A espécie Cymbopogon citratus, conhecida como capim-limão, é amplamente utilizada popularmente para fins medicinais e tem o uso nas indústrias farmacêuticas, alimentícias, de cosméticos e perfumaria. Devido à necessidade de conhecimentos específicos na área de pré-processamento, o presente trabalho tem a finalidade de equacionar e analisar alguns aspectos da secagem, que permitam prever as alterações na qualidade do produto. Folhas da referida espécie foram submetidas a cortes em diferentes comprimentos e à secagem em diferentes temperaturas. Aos dados experimentais, ajustaram-se diferentes equações para a modelagem das curvas de secagem. Realizaram-se também avaliações do produto seco, referentes à cor e ao teor do óleo essencial. Os resultados evidenciam que o modelo de Page Modificado é o que melhor se ajusta aos dados experimentais. A temperatura de 50ºC mostrou-se a mais indicada para a secagem da espécie, resultando em produto com menor perda do óleo essencial e maior preservação da cor verde.The species Cymbopogon citratus, known as lemon grass, is widely used for medicinal purpose and in the pharmaceutical, food, cosmetic and perfumery industries. Due to the need for more specific knowledge of pre-processing management, this work aims to equate and analyze some drying aspects that allow preview the product quality alterations. The leaves from this species were cut at different lengths and dried at different temperatures. Different equations for modeling the drying curves were adjusted to the experimental data. The dried product was also evaluated for color and essential oil content. The results showed that the Modified Page model resulted in the best adjustment for the experimental data. The temperature of 50°C was the best for drying the species leaves, resulting in less essential oil loss and higher green color maintenance.

  17. Variação dos teores de constituintes voláteis de Cymbopogon citratus (DC Staf, Poaceae, coletados em diferentes regiões do Estado de São Paulo Variation in the amounts of volatile constituents of Cymbopogon citratus (DC Staf, Poaceae, collected in different regions of São Paulo State

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    Marcos R. Furlan

    2010-11-01

    Full Text Available O óleo essencial extraído de Cymbopogon citratus (DC Staf, Poaceae, é rico em citral sendo amplamente empregado na indústria química e farmacêutica. Os objetivos desse estudo foram avaliar o conteúdo de citral entre populações de C. citratus coletados em duas regiões diferentes (Ibiúna e Pindamonhangaba, Estado de São Paulo. O óleo essencial extraído de uma população cultivada em Pindamonhangaba-SP apresentou uma concentração alta de citral (aproximadamente 96,0%, enquanto que o óleo extraído da população de Ibiúna-SP apresentou, além de citral, proporções elevadas de outro monoterpeno, o geraniol. Adicionalmente, os óleos essenciais obtidos desta população de C. citratus foram extraídos e analisados ao longo de 24 h (a cada 3 h, sendo que o teor de citral foi maior no período da noite, o que mostra a importância de estudos que avaliam as diferenças químicas associadas às mudanças circadianas. Os componentes dos óleos essenciais foram identificados por RMN de 13C, CG/EM e CG através do índice de Kovats.The essential oil extracted from Cymbopogon citratus (DC Staf, Poaceae, is rich in citral and has many applications in chemical and pharmaceutical industry. The aims of this study were evaluate the amount of citral in populations of C. citratus collected in two different regions (Ibiúna and Pindamonhangaba, São Paulo State. The essential oil extracted of a cultivated population in Pidamonhangaba-SP, showed a high content of citral (approximately 96.0%, while the essential oil from Ibiuna-SP, showed citral and high amounts of another monoterpene, geraniol. Additionally, the essential oils from this population of C. citratus were extracted and analyzed during 24 h (each 3 h, being the major concentration of citral in the night period, indicating that studies which evaluated the chemical differences associated to circadian changes. The components of essential oils were identified through 13C NMR, GC/MS, GC and

  18. Effet comparé des poudres de Nicotiana tabacum L, Cymbopogon citratus (D.C. Stapf et de l'huile de Ricinus communis L sur la conservation des graines de Vigna unguiculata (L Walp

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    Gakuru, S.

    1995-01-01

    Full Text Available Compared Effect of Nicotiana tabacum L, Cymbopogon citratus (D.C. Stapf Powders and Castor Oil Ricinus communis L. on Conservation of Cowpea Vigna Unguiculata (L. Walp Grains. The effect of powder of tobacco Nicotiana tabacum L. and citronella grass Cymbopogon citratus (D.C. Stapf and castor oil Ricinus communis L. on conservation of cowpea Vigna unguiculata (L. Walp. grains was investigated in Kisangani, Zaire. After 5 months of conservation, infestation rates by bean weevil Acanthoscelides obtectus Say were 72.5 %, 74.5 %, 49.5 % and 5 % respectively for the check, the samples treated by 1 % of citronella grass and tobacco powder and 1 % of castor oil. The powder dose of 7.5 % did not give more interesting results.

  19. Aromatic plant oils of the Peruvian Amazon. Part 2: Cymbopogon citratus (DC) Stapf., Renealmia sp., Hyptis recurvata Poit. and Tynanthus panurensis (Bur.) Sandw.

    NARCIS (Netherlands)

    Leclercq, P.A.; Delgado, H.S.; Garcia, J.; Hidalgo, J.E.; Cerrutti, T.; Mestanza, M.; Rios, F.; Nina, E.; Nonato, L.; Alvarado, R.; Menendez, R.

    2000-01-01

    The leaf oils of Cymbopogon citratus (lemongrass), Renealmia sp., and Hyptts recuroata, and the cortex oil of 1jmanthus panurensisfrom Peruvian Amazon have been isolated by hydrodistillation and analyzed by a combination of GC and GC/MS. Twelve, sixteen, and sixteen components have been identified

  20. Melaza de Caña de Azúcar y Suero de Leche como Aditivos en el Ensilaje de Hojas de Zacate de Limón (Cymbopogon citratus [DC.] Stapf)

    OpenAIRE

    Ventura-Canseco, Lucía María Cristina; Mendoza Nunez, José Alfredo; Abud-Archila, Miguel; Oliva-Llaven, Maria Ángela; Dendooven, Luc; Gutiérrez-Miceli, Federico A.

    2012-01-01

    After extraction of essential oil from lemongrass (Cymbopogon citratus [DC.] Stapf) leaves by steam distillation (heat treatment), large amounts of organic wastes are obtained. This by-product could easily be used as animal feed. The potential of sugarcane molasse and whey as additives to ensile lemongrass leaves was investigated. The vegetative material was obtained after essential oils were extracted from lemongrass leaves with steam distillation. Lemongrass leaves were chopped, mixed with ...

  1. Control of anthracnose caused by Colletotrichum species in guava, mango and papaya using synergistic combinations of chitosan and Cymbopogon citratus (D.C. ex Nees) Stapf. essential oil.

    Science.gov (United States)

    Lima Oliveira, Priscila Dinah; de Oliveira, Kataryne Árabe Rimá; Vieira, Willie Anderson Dos Santos; Câmara, Marcos Paz Saraiva; de Souza, Evandro Leite

    2018-02-02

    This study assessed the efficacy of chitosan (Chi) and Cymbopogon citratus (D.C. ex Nees) Stapf. essential oil (CCEO) combinations to control the mycelial growth of five pathogenic Colletotrichum species (C. asianum, C. siamense, C. fructicola, C. tropicale and C. karstii) in vitro, as well as the anthracnose development in guava (Psidium guajava L.) cv. Paluma, mango (Mangifera indica L.) cv. Tommy Atkins and papaya (Carica papaya L.) cv. Papaya artificially inoculated with these species. Combinations of Chi (2.5, 5 or 7.5mg/mL) and CCEO (0.15, 0.3, 0.6 or 1.25μL/mL) inhibited the mycelial growth of all tested fungal species in vitro. Examined Chi-CCEO combinations showed additive or synergistic interactions to inhibit the target Colletotrichum species based on the Abbott index. Coatings formed by synergistic Chi (5mg/mL) and CCEO (0.15, 0.3 or 0.6μL/mL) combinations decreased anthracnose lesion development in guava, mango and papaya inoculated with any of the tested Colleotrichum species during storage. Overall, anthracnose lesion development inhibition in fruit coated with synergistic Chi-CCEO combinations was higher than that observed in fruit treated with synthetic fungicides. These results show that the application of coatings formed by Chi-CCEO synergistic combinations could be effective to control postharvest anthracnose development in fruit. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Growth and physiological response of lemongrass (Cymbopogon citratus (D.C.) Stapf.) under different levels of fly ash-amended soil.

    Science.gov (United States)

    Panda, Debabrata; Panda, Dibyajyoti; Padhan, Bandana; Biswas, Meghali

    2018-05-12

    Revegetation with metal tolerant plants for management of fly ash deposits is an important environmental perspective nowadays. Growth performance, photosynthesis, and antioxidant defense of lemongrass (Cymbopogon citratus (D.C.) Stapf.) were evaluated under various combination of fly ash amended with garden soil in order to assess its fly ash tolerance potential. Under low level of fly ash (25%) amended soil, the plant growth parameters such as shoot, root, and total plant biomass as well as metal tolerance index were increased compared to the control plants grown on garden soil, followed by decline under higher concentration of fly ash (50%, 75% and 100%). In addition, leaf photosynthetic rate, stomatal conductance, and photosystem (PS) II activity were not significantly changed under low level of fly ash (25%) amended soil compared to the garden soil but these parameters were significantly decreased further with increase of fly ash concentrations. Furthermore, increase of activities of some antioxidant enzymes such as superoxide dismutase, ascorbate peroxidase, and guaiacol peroxidase over control were noticed in lemongrass under all fly ash treatments. Taken together, the study suggests that lemongrass can be used for phytoremediation of fly ash at 25% amended soil.

  3. Microscopic investigation to determine the effect of Beauveria bassiana (Bals.) Vuill. and Cymbopogon citratus (DC.) Stapf. treatment on different life stages of Musca domestica (L.).

    Science.gov (United States)

    Mishra, Sapna; Kumar, Peeyush; Malik, Anushree

    2017-06-01

    Microscopic investigation was done to determine the effect of entomopathogenic fungi, Beauveria bassiana and essential oil of Cymbopogon citratus on different life stages of Musca domestica . Scanning electron microscopy investigation of fungal infected larvae showed sluggish movement, rigor, and failure of body to balance in water. Treated larvae also revealed varied level of cuticle shrinkage and extreme dehydration. Surface of B. bassiana infected pupae showed varied stage of mycelial growth, while the cadaver of adult fly was observed to have extensive fungal growth covering their entire body surface. The application of C. citratus oils on M. domestica larvae resulted in skin shrinkage, spinous cells proliferation and bleb formation, while the treated pupae showed high incidence of incomplete emergence and malformation in emerged adult flies. The current study establishes effect of C. citratus essential oil and B. bassiana infection on different life stages of M. domestica .

  4. Inactivation of Escherichia coli, Listeria monocytogenes, and Salmonella Enteritidis by Cymbopogon citratus D.C. Stapf. Essential Oil in Pineapple Juice.

    Science.gov (United States)

    Leite, Caroline Junqueira Barcellos; de Sousa, Jossana Pereira; Medeiros, José Alberto da Costa; da Conceição, Maria Lúcia; dos Santos Falcão-Silva, Vivyanne; de Souza, Evandro Leite

    2016-02-01

    In the present study, the efficacy of Cymbopogon citratus D.C. Stapf. essential oil (CCEO) to provoke a 5-log CFU/ml (5-log) inactivation in a mixed composite of Escherichia coli, Listeria monocytogenes, and Salmonella enterica serovar Enteritidis in pineapple (Ananas comosus (L.) Merril) juice (4°C) was assessed. Moreover, the effects of CCEO on the physicochemical and sensory quality parameters of pineapple juice were evaluated. The MIC of CCEO was 5 μl/ml against the composite mix examined. For L. monocytogenes and E. coli inoculated in juice containing CCEO (5, 2.5, and 1.25 μl/ml), a ≥5-log reduction was detected after 15 min of exposure. This same result was obtained for Salmonella Enteritidis incubated alone in pineapple juice containing CCEO at 5 and 2.5 μl/ml. Overall, Salmonella Enteritidis was the most tolerant and L. monocytogenes was the most sensitive to CCEO. The physicochemical properties (pH, titratable acidic [citric acid per 100 g], and soluble solids) of pineapple juice containing CCEO (2.5 and 1.25 μl/ml) were maintained. Juice containing CCEO (2.5 and 1.25 μl/ml) exhibited similar scores for odor, appearance, and viscosity compared with juice without CCEO. However, unsatisfactory changes in taste and aftertaste were observed in juices containing CCEO. These results suggest that CCEO could be used as an alternative antimicrobial compound to ensure the safety of pineapple juice, although CCEO at the tested concentrations negatively impacted its taste. Therefore, further studies are needed to determine the balance between microbial safety and taste acceptability of pineapple juice containing CCEO.

  5. Chemical composition and cardiovascular effects induced by the essential oil of Cymbopogon citratus DC. Stapf, Poaceae, in rats Composição química e efeitos cardiovasculares do óleo essencial de Cymbopogon citratus DC. Stapf, Poaceae, em ratos

    Directory of Open Access Journals (Sweden)

    Flávia V. Moreira

    2010-12-01

    Full Text Available Cymbopogon citratus DC. Stapf, Poaceae, is used in the folk medicine for hypertension treatment. This work investigated the chemical composition and cardiovascular effects in rats of C. citratus essential oil (EOCC. A phytochemical screening demonstrated the presence of eight constituents, being geranial the major compound (43.08%. In rats, EOCC (1, 5, 10, and 20 mg/kg, i.v. induced transient hypotension and bradycardia that were attenuated by atropine and sodium thiopental, but not by L-NAME or indomethacin. In rings of rat superior mesenteric artery pre-contracted with phenylephrine, EOCC (1 to 3000 µg/mL induced relaxation that was not affected after removal of the endothelium, after TEA or in rings pre-contracted with KCl (80 mM. Furthermore, EOCC (1000 µg/mL was not able to induce additional effect on maximal relaxation of nifedipine (10 µM. In conclusions, EOCC induces hypotension, possibly by reduction in vascular resistance caused by inhibition of the Ca2+ influx, and bradycardia probably due to an activation of cardiac muscarinic receptors.C. citratus é utilizada na medicina popular para tratar hipertensão. Este trabalho investigou a composição química e os efeitos cardiovasculares do óleo essencial do C. citratus (OECC. Foram identificados oito constituintes no OECC, sendo geranial o majoritário (43,08%. Em ratos, o OECC (1, 5, 10 e 20 mg/kg, i.v. induziu hipotensão e bradicardia que foram atenuadas pela atropina e tiopental sódico, mas não por L-NAME ou indometacina. Em anéis de artéria mesentérica de ratos pré-contraídos com fenilefrina, o OECC (1 a 3000 µg/mL induziu relaxamento que não foi afetado após remoção do endotélio, após TEA ou em anéis pré-contraídos com KCl (80 mM. Além disso, o OECC (1000 µg/mL não induziu efeito adicional sobre o relaxamento máximo da nifedipina (10 µM. Em conclusão, o OECC induz hipotensão possivelmente devido à redução da resistência vascular que pode ser causada

  6. Variação dos teores de constituintes voláteis de Cymbopogon citratus (DC Staf, Poaceae, coletados em diferentes regiões do Estado de São Paulo

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    Marcos R. Furlan

    2010-10-01

    Full Text Available O óleo essencial extraído de Cymbopogon citratus (DC Staf, Poaceae, é rico em citral sendo amplamente empregado na indústria química e farmacêutica. Os objetivos desse estudo foram avaliar o conteúdo de citral entre populações de C. citratus coletados em duas regiões diferentes (Ibiúna e Pindamonhangaba, Estado de São Paulo. O óleo essencial extraído de uma população cultivada em Pindamonhangaba-SP apresentou uma concentração alta de citral (aproximadamente 96,0%, enquanto que o óleo extraído da população de Ibiúna-SP apresentou, além de citral, proporções elevadas de outro monoterpeno, o geraniol. Adicionalmente, os óleos essenciais obtidos desta população de C. citratus foram extraídos e analisados ao longo de 24 h (a cada 3 h, sendo que o teor de citral foi maior no período da noite, o que mostra a importância de estudos que avaliam as diferenças químicas associadas às mudanças circadianas. Os componentes dos óleos essenciais foram identificados por RMN de 13C, CG/EM e CG através do índice de Kovats.

  7. Sugarcane Molasse and Whey as Additives in the Silage of Lemongrass (Cymbopogon citratus [DC.] Stapf Leaves Melaza de Caña de Azúcar y Suero de Leche como Aditivos en el Ensilaje de Hojas de Zacate de Limón (Cymbopogon citratus [DC.] Stapf

    Directory of Open Access Journals (Sweden)

    Lucía María Cristina Ventura-Canseco

    2012-03-01

    Full Text Available After extraction of essential oil from lemongrass (Cymbopogon citratus [DC.] Stapf leaves by steam distillation (heat treatment, large amounts of organic wastes are obtained. This by-product could easily be used as animal feed. The potential of sugarcane molasse and whey as additives to ensile lemongrass leaves was investigated. The vegetative material was obtained after essential oils were extracted from lemongrass leaves with steam distillation. Lemongrass leaves were chopped, mixed with sugarcane molasse and whey, placed in cylindrical plastic containers, hermetically closed. The experimental design for pH optimization was a response surface 3-level factorial design 3² with three replicates. Sugarcane molasse at 5, 10 and 15% (w/w and whey at 20, 25 and 30% (w/w were used. The pH of the silage decreased significantly in each treatment, but it was faster when sugarcane molasse was added. The lactic acid concentration was 2.8 g kg-1 DM in silage amended with 15% molasse plus 25% whey and was higher than in silage supplemented with commercial additive after 15 d. In conclusion, it was shown that lemongrass leaves obtained as by product after extracting essential oils can be effectively ensiled with whey and sugarcane molasse as additives inducing a faster production of lactic acid.Después de la extracción del aceite esencial de zacate limón (Cymbopogon citratus [DC.] Stapf por destilación con vapor (tratamiento térmico se obtiene un residuo. Este residuo podría ser utilizado para alimentación animal. El potencial de la melaza de caña y suero de leche como aditivos para ensilar hojas de zacate limón fue investigado. El material vegetal se obtuvo después que los aceites esenciales se extrajeron de las hojas de zacate limón usando destilación con vapor. Las hojas de zacate limón se picaron, mezclaron con melaza de caña y suero de leche y se colocaron en recipientes cilíndricos de plástico y se cerraron herméticamente. El dise

  8. In vitro cytotoxic activity of Cymbopogon citratus L. and Cymbopogon nardus L. essential oils from Togo

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    Koffi Koba

    2009-06-01

    Full Text Available The leaf essential oils of Cymbopogon citratus L. and Cymbopogon nardus L.(Poaceae from Togo were steam-distilled, analyzed for percentage composition and investigated in vitro for their potential cytotoxic activity on human epidermic cell line HaCat. The percentage composition showed that the main constituents of essential oils samples were respectively geranial (45.2%, neral(32.4% and myrcène (10.2% for C. citratus essential oil and citronellal (35.5%, geraniol (27.9% and citronellol (10.7% for that of C. nardus. The in vitro cytotoxicity bioassays on human epidermic cell line HaCaT revealed that the toxicityof the essential oil from C. citratus (IC50: 150 μL.mL-1 was higher than that of the essential oil from C. nardus (IC50: 450 μL.mL-1. Pure commercial neral, geranial, and citronellal standards showed respectively the following IC50 values: 100, 250 and 300 μL.mL-1. Conversely, pure citronellol standard appeared almost non-toxic (IC50>1000 μL.mL-1, proving the major role played in synergyby neral and geranial in the overall toxicity showed by the citratus oil sample tested in this work.

  9. In vitro cytotoxic activity of Cymbopogon citratus L. and Cymbopogon nardus L. essential oils from Togo

    Directory of Open Access Journals (Sweden)

    Koffi Koba

    2009-03-01

    Full Text Available The leaf essential oils of Cymbopogon citratus L. and Cymbopogon nardus L. (Poaceae from Togo were steam-distilled, analyzed for percentage composition and investigated in vitro for their potential cytotoxic activity on human epidermic cell line HaCat. The percentage composition showed that the main constituents of essential oils samples were respectively geranial (45.2%, neral (32.4% and myrc¨ne (10.2% for C. citratus essential oil and citronellal (35.5%, geraniol (27.9% and citronellol (10.7% for that of C. nardus. The in vitro cytotoxicity bioassays on human epidermic cell line HaCaT revealed that the toxicity of the essential oil from C. citratus (IC50: 150 µL.mL-1 was higher than that of the essential oil from C. nardus (IC50: 450 µL.mL-1. Pure commercial neral, geranial, and citronellal standards showed respectively the following IC50 values: 100, 250 and 300 µL.mL-1. Conversely, pure citronellol standard appeared almost non-toxic (IC50>1000 µL.mL-1, proving the major role played in synergy by neral and geranial in the overall toxicity showed by the citratus oil sample tested in this work.

  10. Treatment of pityriasis versicolor with topical application of essential oil of Cymbopogon citratus (DC Stapf - therapeutic pilot study Tratamento de pitiríase versicolor com aplicação tópica do óleo essencial de Cymbopogon citratus (DC Stapf - estudo terapêutico piloto

    Directory of Open Access Journals (Sweden)

    Egberto Santos Carmo

    2013-06-01

    Full Text Available BACKGROUND: Pityriasis versicolor is a fungal infection caused by Malassezia spp. that has frequent relapses. OBJECTIVES: The main objective of this research was to perform phase I and II clinical studies, using formulations containing essential oil of Cymbopogon citratus in patients with pityriasis versicolor. METHODS: Phase I study included twenty volunteers to ascertain the safety of the formulations. In phase II, 47 volunteers randomly received essential oil formulations at 1.25 μL/mL concentration, for forty days. The shampoo should be applied three times a week and the cream twice a day. A control group in phase II, consisting of 29 volunteers, received the same formulations but with 2% ketoconazole as the active ingredient. RESULTS: No significant adverse events were observed in volunteers during Phase I. In Phase II, 30 (63.83% volunteers using essential oil and 18 (62.07% using ketoconazole remained until the end of the study. We observed a predominance of lesions in disseminated form, with M. sympodialis detected as the predominant agent identified in cultures. After 40 days of treatment, the rate of mycological cure was 60% (p FUNDAMENTOS: Pitiríase versicolor é uma micose causada pela Malassezia spp., e que apresenta frequentes recidivas. OBJETIVOS: Este trabalho objetivou realizar estudos clínicos de fase I e II, para essa patologia, com óleo essencial de Cymbopogon citratus. MÉTODOS: Na fase I, participaram vinte voluntários para averiguar a segurança das formulações. Na fase II, 47 voluntários receberam as formulações do óleo essencial a 1,25 μL/mL, as quais deveriam ser utilizadas por quarenta dias, sendo o xampu três vezes por semana e o creme duas vezes ao dia. Um grupo controle na fase II, constituído por 29 voluntários recebeu as mesmas formulações, com cetoconazol a 2%. RESULTADOS: Verificada a segurança das formulações com a finalização da fase I, onde nenhuma reação adversa significativa foi

  11. Gastroprotective effect of Cymbopogon citratus infusion on acute ethanol-induced gastric lesions in rats.

    Science.gov (United States)

    Sagradas, Joana; Costa, Gustavo; Figueirinha, Artur; Castel-Branco, Maria Margarida; Silvério Cabrita, António Manuel; Figueiredo, Isabel Vitória; Batista, Maria Teresa

    2015-09-15

    Treatment of gastric ulcers with medicinal plants is quite common in traditional medicine worldwide. Cymbopogon citratus (DC) Stapf. leaves infusion has been used in folk medicine of many tropical and subtropical regions to treat gastric disturbances. The aim of this study was to assess the potential gastroprotective activity of an essential oil-free infusion from C. citratus leaves in acute gastric lesions induced by ethanol in rat. The study was performed on adult male Wistar rats (234.0±22.7g) fasted for 24h but with free access to water. The extract was given orally before (prevention) or after (treatment) intragastric administration of absolute ethanol. Effects of dose (28 or 56mg/kg of body weight) and time of contact of the extract with gastric mucosa (1 or 2h) were also assessed. Animals were sacrificed, being the stomachs removed and the lesions were assessed by macroscopic observation and histopathology. C. citratus extract, given orally before or after ethanol, significantly (P<0.01) reduced gastric mucosal injury compared with control group (vehicle+ethanol). The effect does not appear to be dose-dependent. Results also suggested that the extract is more effective when the time of contact with gastric mucosa increases. The results of this assay confirm the gastroprotective activity of C. citratus extract on experimental gastric lesions induced by ethanol, contributing for the pharmacological validation of its traditional use. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  12. Anthelmintic activity of Cymbopogon citratus against Haemonchus contortus

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    Iara Tersia Freitas Macedo

    Full Text Available Parasitic nematodes are of major economic importance in livestock. An alternative for the control of parasites is phytotherapy. This study evaluated the efficacy of Cymbopogon citratus decoction (CcD, C. citratus essential oil (CcEo and citral against Haemonchus contortus using in vitro egg hatch test (EHT and larval development test (LDT and an in vivo test using a Meriones unguiculatus (gerbil model. The effect of 800 mg/kg CcEo was evaluated in gerbils that had been artificially infected with 5,000 third-stage H. contortus larvae. The effective concentrations required to inhibit 50% (EC50 of egg hatching were 0.46, 0.14 and 0.13 mg/mL for CcD, CcEo and citral, respectively. The EC50 values in the LDT were 5.04, 1.92 and 1.37 mg/mL for CcD, CcEo and citral, respectively. H. contortus population in the group treated with C. citratus essential oil was reduced by 38.5% (P< 0.05 in comparison to the control group. These results suggest that it may be possible to use C. citratusessential oil to control of H. contortus parasite of small ruminant.

  13. Antifungal activity of Cymbopogon citratus against Colletotrichum gloesporioides

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    Alexander Francisco Pérez Cordero

    2017-04-01

    Full Text Available The objective of this research was to evaluate in vitro the inhibitory activity of essential oils from fresh leaves of Cymbopogon citratus (lemongrass against Colletotrichum gloeosporioides in yam. The research was conducted in the department of Sucre, Colombia. The essential oils of C. citratus were collected in the municipalities of Sincelejo, La Union and Sampues, in September and October 2015. The essential oil was extract from fresh leaves using the microwave-assisted hydrodistillation. Concentrations of 5000, 8000 and 10 000 ppm of each essential oil were prepared. An absolute control, a positive control (benomyl 1 g/l and a negative control was used. An inhibitory activity was obtained by using the direct seeding on surface of the potato-dextrose-agar method and it was expressed as percentage of inhibition rate. The chemical characterization of essential oils was performed by gas chromatography coupled to mass spectrometry. The highest percentages of antifungal index were observed in the lemongrass from Sincelejo at concentrations of 5000, 8000 and 10 000 ppm, after in La Union at 8000 and 10 000 ppm, and finally at Sampues at 10 000 ppm, with a value of 97.77%; the effect was similar to the positive control with benomyl 1 g/l. Citral was the main constituent of the essential oils extracted. The essential oils obtained from the three municipalities showed antifungal activity against C. gloeosporioides.

  14. AVALIAÇÃO DE POTENCIAL DE ERVAS MEDICINAIS: CAPIM-LIMÃO (Cymbopogon citratus D.C., CHÁ VERDE (Camellia sinensis L. E HIBISCO (Hibiscus sabdariffa L. PARA OBTENÇÃO DE CHÁS SOLÚVEIS

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    Uellison dos Santos

    2014-12-01

    Full Text Available Este trabalho foi realizado com o objetivo de avaliar características físico-químicas de extrato aquoso e liofilizado de capim-limão (Cymbopogon citratus D.C., chá verde (Camellia sinensis L. e hibisco (Hibiscus sabdariffa L., foram realizadas analises em triplicata  de teor de sólidos solúveis, acidez titulável, pH, atividade de água e solubilidade em água. Os resultados do extrato aquoso e liofilizado para o capim limão apresentaram (SST variando de 3,0333 a 38,3066, valores de pH variando de 5,08 e 6,32 além de atividade de água características para os estados em que os extratos se encontravam, para o resultado do chá verde obtivemos teor de (SST variando de 2,81 a 45,52, pH entre 5,04 e 6,28 além de atividade de água característica. Os extratos de hibisco também apresentaram resultados satisfatórios com teor (SST entre 3,28 e 34,16, pH de 2,34 e 3,16 e atividade de água característica.  Os resultados obtidos revelaram a importância do processo de liofilização nas amostras, uma vez que houve um aumento da qualidade dos chás sem que houvesse danos na sua qualidade sensorial.

  15. In Vitro Mass Propagation of Cymbopogon citratus Stapf., a Medicinal Gramineae.

    Science.gov (United States)

    Quiala, Elisa; Barbón, Raúl; Capote, Alina; Pérez, Naivy; Jiménez, Elio

    2016-01-01

    Cymbopogon citratus (D.C.) Stapf. is a medicinal plant source of lemon grass oils with multiple uses in the pharmaceutical and food industry. Conventional propagation in semisolid culture medium has become a fast tool for mass propagation of lemon grass, but the production cost must be lower. A solution could be the application of in vitro propagation methods based on liquid culture advantages and automation. This chapter provides two efficient protocols for in vitro propagation via organogenesis and somatic embryogenesis of this medicinal plant. Firstly, we report the production of shoots using a temporary immersion system (TIS). Secondly, a protocol for somatic embryogenesis using semisolid culture for callus formation and multiplication, and liquid culture in a rotatory shaker and conventional bioreactors for the maintenance of embryogenic culture, is described. Well-developed plants can be achieved from both protocols. Here we provide a fast and efficient technology for mass propagation of this medicinal plant taking the advantage of liquid culture and automation.

  16. Scientific basis for the therapeutic use of Cymbopogon citratus, stapf (Lemon grass

    Directory of Open Access Journals (Sweden)

    Gagan Shah

    2011-01-01

    Full Text Available Cymbopogon citratus, Stapf (Lemon grass is a widely used herb in tropical countries, especially in Southeast Asia. The essential oil of the plant is used in aromatherapy. The compounds identified in Cymbopogon citratus are mainly terpenes, alcohols, ketones, aldehyde and esters. Some of the reported phytoconstituents are essential oils that contain Citral a, Citral b, Nerol Geraniol, Citronellal, Terpinolene, Geranyl acetate, Myrecene and Terpinol Methylheptenone. The plant also contains reported phytoconstituents such as flavonoids and phenolic compounds, which consist of luteolin, isoorientin 2′-O-rhamnoside, quercetin, kaempferol and apiginin. Studies indicate that Cymbopogon citratus possesses various pharmacological activities such as anti-amoebic, antibacterial, antidiarrheal, antifilarial, antifungal and anti-inflammatory properties. Various other effects like antimalarial, antimutagenicity, antimycobacterial, antioxidants, hypoglycemic and neurobehaviorial have also been studied. These results are very encouraging and indicate that this herb should be studied more extensively to confirm these results and reveal other potential therapeutic effects.

  17. Data showing chemical compositions of the essential oils of the leaves of Cymbopogon citratus obtained by varying pH of the extraction medium

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    E.O. Ajayi

    2016-09-01

    Full Text Available This article describes the various chemical components as obtained from the oils in the leaves of Cymbopogon citratus using hydrodistillation and solvent-free microwave extraction methods. Furthermore, extractions of the oils were also carried out with a slight in pH variation and compared, “GC–MS evaluation of C. citratus (DC Stapf oil obtained using modified hydrodistillation and microwave extraction methods” (Ajayi et al., 2016 [1]. The current article contains one table exhibiting a list of compounds in the four different methods of extraction. Comparative studies amongst the various methods of extraction are highlighted in the table. Keywords: Essential oil, Cymbopogon citratus, pH Extraction medium

  18. Bioactivity of essential oil from lemongrass (Cymbopogon citratus Stapf) as antioxidant agent

    Science.gov (United States)

    Anggraeni, Nenden Indrayati; Hidayat, Ika Wiani; Rachman, Saadah Diana; Ersanda

    2018-02-01

    Free radical induced oxidative stress that influences the occurrence of various degenerative diseases such as cancer, coronary heart disease and premature aging. In the case that body's antioxidant defense system does not have excessive antioxidants, additional natural antioxidant via food or other nutrients intake is needed. Stems of lemongrass Cymbopogon citratus Stapf are known to contain phenolic compounds that are known to have antioxidant activity. Lemongrass (Cymbopogon citratus Stapf) plant is well known herb in Asia, espesially in Indonesia and used for cooking and has many health benefits. A study has been carried out to determine antioxidant potential of stems of lemongrass. In this the primary study is to examine essential oil Cymbopogon citratus Stapf from Cileles Jatinangor as an antioxidant agent. Essential oil of Cymbopogon citratus Stapf was isolated from 1272 g of dried stem by using Karlsruhe steam distillation methods with 0.24% in yield. The product of essential oil was also tested against antioxidant activity DPPH and resulted low activity compare to ascorbic acid and lemongrass oil standard as reference material.

  19. Efficacité des huiles essentielles de Cymbopogon citratus et de ...

    African Journals Online (AJOL)

    essential oils extracted from leaves of Cymbopogon citratus and Mentha piperita in conservation of fresh cow's milk in southern Benin. ... Mentha piperita essential oil has menthol (46.7%) and neomenthol (8.28%) as major compounds with a hydrogenated ..... des feuilles et fruits de Xylopia aethiopica (Dunal) A. Rich.

  20. Cymbopogon citratus and Cymbopogon giganteus essential oils have cytotoxic effects on tumor cell cultures. Identification of citral as a new putative anti-proliferative molecule.

    Science.gov (United States)

    Bayala, Bagora; Bassole, Imaël H N; Maqdasy, Salwan; Baron, Silvère; Simpore, Jacques; Lobaccaro, Jean-Marc A

    2018-03-06

    Cymbopogon species are used as traditional remedies in Burkina Faso for treating several diseases. We aimed to study the effects of their essential oils on cancer cell lines. For that purpose, Cymbopogon citratus (DC.) Stapf. and Cymbopogon giganteus Chiov. were studied for their essential oils after various chemical extractions. Antioxidant, potential anti-inflammatory action (inhibition of lipoxygenase) and cytotoxic activities were also tested on various prostate cancer and glioblastoma cell lines. Thirty-three compounds were identified in the essential oil of C. giganteus: Limonene (19.33%), Mentha-1(7),8-dien-2-ol cis (17.34%), Mentha-1(7),8-dien-2-ol trans (13.95%), trans-Mentha-2,8-diene-para-ol 1 (13.91%) and Mentha-2,8-diene-1-ol, cis-para (8.10%) were the most abundant. C. citratus essential oil contained 15 compounds and the major ones were geranial/citral A (48.18%) and neral/citral B (34.37%). Essential oil of C. citratus showed the highest ability to scavenge DPPH + radicals (approximately 68% at 8 mg/mL) while C. giganteus exhibited the highest capability to reduce ABTS + (0.59μmolET/g). The essential oil of C. citratus was the most effective on prostate cell lines LNCaP (IC 50  = 6.36 μg/ml) and PC-3 (IC 50  = 32.1 μg/ml), and on glioblastoma cell lines (SF-767 (IC 50  = 45.13 μg/ml) and SF-763 (IC 50  = 172.05 μg/ml). Interestingly, the activity of essential oil of C. citratus was statistically equal to that of its major component, citral. Combination of both oils showed antagonist, additive, indifferent and synergistic effects on LNCaP, PC-3, SF-767 and SF-763 cell lines, respectively. In conclusion, plants from the traditional medicine in Burkina Faso could be of interest for identifying new compounds, such as citral, for the treatment of prostate cancer and glioblastoma. Copyright © 2018 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

  1. Food preservative potential of essential oils and fractions from Cymbopogon citratus, Ocimum gratissimum and Thymus vulgaris against mycotoxigenic fungi

    DEFF Research Database (Denmark)

    Nguefack, J.; Dongmo, J. B. Lekagne; Dakole, C. D.

    2009-01-01

    The food preservative potential of essential oils from three aromatic plants Cymbopogon citratus, Ocimum gratissimum and Thymus vulgaris and their fractions was investigated against two mycotoxigenic strains each of Aspergillus ochraceus, Penicillium expansum and P. verrucosum. The fungicidal...

  2. Produtividade e qualidade do óleo essencial de capim-limão, Cymbopogon citratus, DC., submetido a diferentes lâminas de irrigação

    Directory of Open Access Journals (Sweden)

    D.A. Pinto

    2014-03-01

    Full Text Available Devido às poucas informações sobre as práticas de cultivo do capim-limão (Cymbopogon citratus, DC. objetivou-se avaliar o efeito de lâminas de irrigação sobre: a produção de biomassa, o rendimento e composição do óleo essencial. O experimento foi instalado em ambiente protegido para possibilitar o controle das lâminas de irrigação e avaliar a viabilidade para situações em que as condições climáticas normais sejam inadequadas. O delineamento experimental foi em blocos inteiramente casualizados com cinco tratamentos e três repetições. Os dados foram submetidos à análise de variância pelo tese F e as médias comparadas pelo teste de Tukey a 5% de probabilidade. Na etapa um, os tratamentos consistiram da aplicação de lâminas referentes a 50%, 75%, 100%, 125% da evapotranspiração da cultura (ETc, irrigando duas vezes por semana e de 100% da evapotranspiração da cultura (ETc, irrigando uma vez por semana, sendo denominados de T1, T2, T3, T4 e T5, respectivamente. Na etapa dois, os tratamentos consistiram da aplicação de lâminas referentes a 50%, 75%, 100%, 125% da ETc irrigando uma vez por semana e de 100% da ETc, irrigando a cada 14 dias, sendo denominados de T6, T7, T8, T9 e T10 respectivamente. O corte do capim-limão foi realizado após 60 dias do início dos tratamentos. Avaliou-se a altura de plantas, o número de perfilhos por touceira, a massa seca da parte aérea, o rendimento e a composição do óleo essencial. O T5, caracterizado por estresse hídrico e intervalo de irrigação moderado, foi o que apresentou a maior produção de matéria seca, maior produtividade do capim-limão e maior estimativa da produtividade de óleo essencial e maior concentração de citral, na primeira etapa. Na etapa dois, o T6, correspondente ao estresse hídrico crescente e acentuado, foi o que apresentou maior estimativa da produtividade de óleo essencial. De acordo com os resultados observados, não foi possível definir

  3. Efficacy of essential oils of Cymbopogon citratus (D.C.) Stapf, Lippia multiflora Moldenke and hot water in the control of seed-borne fungi Phoma sorghina and their effects on Sorghum bicolor (L.) Moench seed germination and plants development in Burkina Faso

    OpenAIRE

    Schémaeza BONZI1; Irénée SOMDA; Paco SEREME; Toudou ADAM

    2013-01-01

    The effects of two essential oils (Cymbopogon citratus and Lippia multiflora) and varying durations of hot water at 50°C on seed-borne fungi Phoma sorghina on five varieties of sorghum were evaluated using morphological traits. The varieties were ICSV 1001, Sariaso 03, ICSV 1049, Kapelga and the local variety, 1341So07. The results indicate that hot water treatment and essential oil of C. citratus significantly reduced the infection level of P. sorghina compared to untreated seeds, seeds trea...

  4. Polyphenols from Cymbopogon citratus leaves as topical anti-inflammatory agents.

    Science.gov (United States)

    Costa, Gustavo; Ferreira, João Pinto; Vitorino, Carla; Pina, Maria Eugénia; Sousa, João José; Figueiredo, Isabel Vitória; Batista, Maria Teresa

    2016-02-03

    A variety of plant polyphenols have been reported to have anti-inflammatory, frequently associated with erythema, edema, hyperplasia, skin photoaging and photocarcinogenesis. Cymbopogon citratus (DC). Stapf (Poaceae) is a worldwide known medicinal plant, used in traditional medicine in inflammation-related conditions. In this work, the anti-inflammatory potential of C. citratus infusion (CcI) and its polyphenols as topical agents was evaluated in vivo. The plant extract was prepared and its fractioning led two polyphenol-rich fractions: flavonoids fraction (CcF) and tannins fraction (CcT). An oil/water emulsion was developed with each active (CcI, CcF+CcT and diclofenac), pH and texture having been evaluated. Release tests were further performed using static Franz diffusion cells and all collected samples were monitored by HPLC-PDA. In vivo topical anti-inflammatory activity evaluation was performed by the carrageenan-induced rat paw edema model. The texture analysis revealed statistically significant differences for all tested parameters to CcF+CcT, supporting its topical application. Release experiments lead to the detection of the phenolic compounds from each sample in the receptor medium and the six major flavonoids were quantified, by HPLC-PDA: carlinoside, isoorientin, cynaroside, luteolin 7-O-neohesperidoside, kurilesin A and cassiaoccidentalin B. The CcF+CcT formulation prompted to the higher release rate for all these flavonoids. CcI4%, CcI1% and CcF+CcT exhibited an edema reduction of 43.18, 29.55 and 59.09%, respectively. Our findings highlight that CcI, containing luteolin 7-O-neohesperidoside, cassiaoccidentalin B, carlinoside, cynaroside and tannins have a potential anti-inflammatory topical activity, suggesting their promising application in the treatment of skin inflammatory pathologies. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  5. Manipulation of rumen ecology by dietary lemongrass (Cymbopogon citratus Stapf.) powder supplementation.

    Science.gov (United States)

    Wanapat, M; Cherdthong, A; Pakdee, P; Wanapat, S

    2008-12-01

    This experiment was conducted to investigate the effect of lemongrass [Cymbopogon citratus (DC.) Stapf.] powder (LGP) on rumen ecology, rumen microorganisms, and digestibility of nutrients. Four ruminally fistulated crossbred (Brahman native) beef cattle were randomly assigned according to a 4 x 4 Latin square design. The dietary treatments were LGP supplementation at 0, 100, 200, and 300 g/d with urea-treated rice straw (5%) fed to allow ad libitum intake. Digestibilities of DM, ether extract, and NDF were significantly different among treatments and were greatest at 100 g/d of supplementation. However, digestibility of CP was decreased with LGP supplementation (P 0.05). Total viable bacteria, amylolytic bacteria, and cellulolytic bacteria were significantly different among treatments and were greatest at 100 g/d of supplementation (4.7 x 10(9), 1.7 x 10(7), and 2.0 x 10(9) cfu/mL, respectively). Protozoal populations were significantly decreased by LGP supplementation. In addition, efficiency of rumen microbial N synthesis based on OM truly digested in the rumen was enriched by LGP supplementation, especially at 100 g/d (34.2 g of N/kg of OM truly digested in the rumen). Based on this study, it could be concluded that supplementation of LGP at 100 g/d improved digestibilities of nutrients, rumen microbial population, and microbial protein synthesis efficiency, thus improving rumen ecology in beef cattle.

  6. Combination of Cymbopogon citratus and Allium cepa essential oils increased antibacterial activity in leafy vegetables.

    Science.gov (United States)

    Ortega-Ramirez, Luis A; Silva-Espinoza, Brenda A; Vargas-Arispuro, Irasema; Gonzalez-Aguilar, Gustavo A; Cruz-Valenzuela, M Reynaldo; Nazzaro, Filomena; Ayala-Zavala, J Fernando

    2017-05-01

    Cymbopogon citratus and Allium cepa essential oils (EOs) are rich in terpenes and sulfur compounds respectively, both with antibacterial activity and different cell targets, supporting the idea that their combination can increase their efficacy. Major constituents of C. citratus were geranial and neral, while A. cepa presented dipropyl disulfide and dipropyl trisulfide. Cymbopogon citratus and A. cepa EOs inhibited the in vitro growth of Escherichia coli O157:H7 (minimal inhibitory concentrations of 2.21 and 5.13 g L -1 respectively), Salmonella Choleraesuis (3.04 and 1.28 g L -1 ), Listeria monocytogenes (1.33 and 2.56 g L -1 ) and Staphylococcus aureus (0.44 and 5.26 g L -1 ). Application of the EO combination to spinach caused a greater reduction in E. coli (2.34 log colony-forming units (CFU) g -1 ), S. Choleraesuis (2.94 log CFU g -1 ), L. monocytogenes (2.06 log CFU g -1 ) and S. aureus (1.37 log CFU g -1 ) compared with higher doses of individual EOs; a similar effect was observed for romaine lettuce. Individual and combined EOs caused a reduction in flavor acceptability level; however, no significant differences were found among odor acceptability of control vegetables and those treated with the EO combination and C. citratus EO. Leafy vegetables treated with the EO combination showed higher antibacterial protection and odor acceptability compared with individual EO treatments. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  7. Hepatoprotective and antioxidant effects of Cymbopogon citratus Stapf

    African Journals Online (AJOL)

    citratus Stapf (Lemon grass) extract in paracetamol- induced hepatotoxicity in ... liver were observed in rats treated with PCM alone compared with control (p < 0.05). .... Table 1: Effect of CS extract on serum markers of PCM-induced toxicity rats.

  8. Phytoconstituents and diuretic activity of Cymbopogon citratus leaf infusions in humans

    Directory of Open Access Journals (Sweden)

    Christopher Ekpenyong

    2014-09-01

    Full Text Available Objective: To assess the diuretic activity of infusions prepared from Cymbopogon citratus (C. citratus leaves in healthy volunteers. Methods: One hundred and five subjects (55 men and 50 women aged 18 to 35 years were randomly assigned to groups set to orally receive infusions prepared from 2, 4, or 8 g of C. citratus leaf powder, once daily for 30 d. Urine volume, frequency of urination, urine specific gravity, and plasma and urinary levels of electrolytes were assessed 1 day before (baseline, and at 10 and 30 d after initiation of treatment. Computed diuretic indices were compared between experimental and baseline values. Results: Subjects treated with infusions prepared from C. citratus leaf powder which tested positive for saponins, tannins, flavaniods, phenols, anthraquinones, alkaloids, and deoxy-sugar exhibited a significant increase in indices of diuresis including urine volume, urination frequency, diuretic action, natriuretic and saliuretic indices and renal fractional excretion of electrolytes and metabolic acidosis. A non-significant change in urine specific gravity was observed in all groups. eGFR showed a non-significant increase at Day 10, but decreased significantly (P<0.05 at Day 30. Thiazide and aldosterone secretion indices decreased at Day 10, whereas carbonic anhydrase index increased significantly (P<0.05 at both Days 10 and 30. Conclusions: These results indicate a loop active diuretic action of C. citratus infusion.

  9. Control of Colletotrichum gloeosporioides (penz.) Sacc. In yellow passion fruit using Cymbopogon citratus essential oil

    Science.gov (United States)

    Anaruma, Nina Duarte; Schmidt, Flávio Luís; Duarte, Marta Cristina Teixeira; Figueira, Glyn Mara; Delarmelina, Camila; Benato, liane Aparecida; Sartoratto, Adilson

    2010-01-01

    The use of antibiotics in agriculture is limited when compared to their applications in human and veterinary medicine. On the other hand, the use of antimicrobials in agriculture contributes to the drug resistance of human pathogens and has stimulated the search for new antibiotics from natural products. Essential oils have been shown to exert several biological activities including antibacterial and antifungal actions. The aim of this study was to determine the activity of 28 essential oils from medicinal plants cultivated at CPMA (Medicinal and Aromatic Plants Collection), CPQBA/UNICAMP, against Colletotrichum gloeosporioides (Penz.) Sacc., the anthracnose agent in yellow passion fruit (Passiflora edulis Sims f. flavicarpa Deg), as well as evaluating their effect in the control of post-harvest decay. The oils were obtained by water-distillation using a Clevenger-type system and their minimal inhibitory concentrations (MIC) determined by the micro-dilution method. According to the results, 15 of the 28 essential oils presented activity against Colletotrichum gloeosporioides, and the following four oils presented MIC values between 0.25 and 0.3 mg/mL: Coriandrum sativum, Cymbopogon citratus, Cymbopogon flexuosus and Lippia alba. The evaluation of Cymbopogon citratus essential oil in the control of post-harvest decay in yellow passion fruit showed that the disease index of the samples treated with the essential oil did not differ (P ≤ 0.05) from that of the samples treated with fungicide. The present study shows the potential of Cymbopogon citratus essential oil in the control of the anthracnose agent in yellow passion fruit. PMID:24031465

  10. Control of Colletotrichum gloeosporioides (penz. Sacc. In yellow passion fruit using Cymbopogon citratus essential oil

    Directory of Open Access Journals (Sweden)

    Nina Duarte Anaruma

    2010-03-01

    Full Text Available The use of antibiotics in agriculture is limited when compared to their applications in human and veterinary medicine. On the other hand, the use of antimicrobials in agriculture contributes to the drug resistance of human pathogens and has stimulated the search for new antibiotics from natural products. Essential oils have been shown to exert several biological activities including antibacterial and antifungal actions. The aim of this study was to determine the activity of 28 essential oils from medicinal plants cultivated at CPMA (Medicinal and Aromatic Plants Collection, CPQBA/UNICAMP, against Colletotrichum gloeosporioides (Penz. Sacc., the anthracnose agent in yellow passion fruit (Passiflora edulis Sims f. flavicarpa Deg, as well as evaluating their effect in the control of post-harvest decay. The oils were obtained by water-distillation using a Clevenger-type system and their minimal inhibitory concentrations (MIC determined by the micro-dilution method. According to the results, 15 of the 28 essential oils presented activity against Colletotrichum gloeosporioides, and the following four oils presented MIC values between 0.25 and 0.3 mg/mL: Coriandrum sativum, Cymbopogon citratus, Cymbopogon flexuosus and Lippia alba. The evaluation of Cymbopogon citratus essential oil in the control of post-harvest decay in yellow passion fruit showed that the disease index of the samples treated with the essential oil did not differ (P < 0.05 from that of the samples treated with fungicide. The present study shows the potential of Cymbopogon citratus essential oil in the control of the anthracnose agent in yellow passion fruit.

  11. Essential Oil of Cymbopogon citratus on the Control of the Curvularia Leaf Spot Disease on Maize

    Science.gov (United States)

    Mourão, Dalmarcia de Sousa Carlos; Ferreira de Souza Pereira, Talita; de Souza, Danival José; Chagas Júnior, Aloísio Freitas; Veloso, Ronice Alves; Leão, Evelynne Urzêdo

    2017-01-01

    The Curvularia Leaf Spot is becoming more common due to the culture expansion and the low resistance of the cultivated genotypes in tropical regions. Thus, the objective was to evaluate the fungitoxicity of the essential oil of Cymbopogon citratus upon the phytopathogen Curvularia lunata, causative agent of the Curvularia Leaf Spot. There was realized pathogenicity tests of C. lunata in maize plants, phytotoxicity of the essential oil of C. citratus and gas chromatography attached, germination tests of the conidia, and of in vitro inhibition of C. lunata. Also, there were realized tests aiming at verifying the phytopathogen control in vivo. In the pathogenicity tests, there were verified symptoms of the disease in all of the suspensions tested on plants. It was observed that the essential oil concentrations of 7.5 µL mL−1 to 50 µL mL−1 were phytotoxic. The majoritarian chemical components of the essential oil of C. citratus were Geranial (41.46%) and Neral (32.43%). The concentrations of 5 and 7.5 µL mL−1 inhibited 100% of conidia germination. None of the concentrations evaluated effectively inhibited C. lunata mycelial growth in in vitro tests. In the preventive control, the concentration of 7.5 µL mL−1 was sufficient for the reduction of the progress of the disease, however the curative control was not efficient on the tested dosages. PMID:28930276

  12. Lemon grass (Cymbopogon citratus essential oil as a potent anti-inflammatory and antifungal drugs

    Directory of Open Access Journals (Sweden)

    Mohamed Nadjib Boukhatem

    2014-09-01

    Full Text Available Background: Volatile oils obtained from lemon grass [Cymbopogon citratus (DC. Stapf, Poaceae family] are used in traditional medicine as remedies for the treatment of various diseases. Aims: In the present study, lemon grass essential oil (LGEO was evaluated for its in vivo topical and oral anti-inflammatory effects, and for its in vitro antifungal activity using both liquid and vapor phases. Methods: The chemical profile of LGEO as determined by gas chromatography–mass spectrometry analysis revealed two major components: geranial (42.2%, and neral (31.5%. The antifungal activity of LGEO was evaluated against several pathogenic yeasts and filamentous fungi using disc diffusion and vapor diffusion methods. Results: LGEO exhibited promising antifungal effect against Candida albicans, C. tropicalis, and Aspergillus niger, with different inhibition zone diameters (IZDs (35–90 mm. IZD increased with increasing oil volume. Significantly, higher anti-Candida activity was observed in the vapor phase. For the evaluation of the anti-inflammatory effect, LGEO (10 mg/kg, administered orally significantly reduced carrageenan-induced paw edema with a similar effect to that observed for oral diclofenac (50 mg/kg, which was used as the positive control. Oral administration of LGEO showed dose-dependent anti-inflammatory activity. In addition, topical application of LGEO in vivo resulted in a potent anti-inflammatory effect, as demonstrated by using the mouse model of croton oil-induced ear edema. To our knowledge, this is the first such report to be published. The topical application of LGEO at doses of 5 and 10 µL/ear significantly reduced acute ear edema induced by croton oil in 62.5 and 75% of the mice, respectively. In addition, histological analysis clearly confirmed that LGEO inhibits the skin inflammatory response in animal models. Conclusion: Results of the present study indicate that LGEO has a noteworthy potential for the development of drugs for

  13. Evaluation of the lemongrass plant (Cymbopogon citratus extracted in different solvents for antioxidant and antibacterial activity against human pathogens

    Directory of Open Access Journals (Sweden)

    Balachandar Balakrishnan

    2014-02-01

    Full Text Available Objective: To test antibacterial and antioxidant activity of the lemongrass plant Cymbopogon citratus (C. citratus leaves extracted serially by the solvents (chloroform, methanol and water. Methods: The plant leaves extracts were used for antibacterial activity on Bacillus subtilis, Pseudomonas aeruginosa, Proteus vulgaris, Staphylococcus aureus, Nocardia sp., Serratia sp., and Enterobacter aeruginosa microorganisms by the Kirby Bauer agar disc diffusion method. This study was carried out on lemongrass plant leaf extracts in different concentration of all solvents. The leaf extracts from different solvents were tested for their scavenging activity against the stable free radical DPPH in quantization using a spectrophotometric assay. Oxidative damage was induced in vitro by treating blood DNA and analyzing the effects of the leaf extracts. Results: The results showed that C. citratus extracts exhibited maximum zones of inhibition in chloroform, methanol and water extracts. It was Observed that the C. citratus extracts exhibited maximum zone of inhibition against Bacillus subtilis, Pseudomonas aeruginosa and Proteus vulgaris. Analyzed data in the present work suggested that antibacterial activity of C. citratus plant leaf extracts showed good results for Gram-positive and Gram-negative organisms. DPPH scavenging activity was highly elicited by the extract of C. citratus. Chloroform, methanol and water extracts of C. citratus leaves effectively decreased the extent of DNA damage. Conclusions: The present study suggested that the lemongrass plant extracts could offer various health benefits.

  14. Pharmacological evaluation of anxiolytic property of aqueous root extract of Cymbopogon citratus in mice

    Directory of Open Access Journals (Sweden)

    David Arome

    2014-01-01

    Full Text Available Aim: This study was designed to evaluate the anxiolytic property of aqueous root extract of Cymbopogon citratus in mice. Materials and Methods: In this study, stress induced hyperthermia (SIH, elevated plus maze (EPM and open field experimental models were employed. Results: In SIH model, the extract caused a significant (P 0.05 effect. In open field model, 200 mg/kg and 600 mg/kg extract doses significantly (P < 0.05 increased locomotion of the mice more than the standard, while rearing and defecation were less in the extract groups. Conclusion: In different experimental models used significant anxiolytic effect was observed of the aqueous extract at different dose levels in comparison to reference standard and normal saline group. This clearly justified its folkloric application in the treatment of anxiety disorders.

  15. [Alcoholic extract of lemongrass (Cymbopogon citratus) on the control of Boophilus microplus in cattle].

    Science.gov (United States)

    Heimerdinger, Arli; Olivo, Clair J; Molento, Marcelo B; Agnolin, Carlos A; Ziech, Magnos F; Scaravelli, Luciene Fernanda B; Skonieski, Fernando R; Both, José F; Charão, Pablo S

    2006-01-01

    The objective of this study was to determine the effect of lemongrass (Cymbopogon citratus) alcoholic extracts on the control of Boophilus microplus in naturally infested Holstein cows. Twelve animals were allocated in three groups of four animals. Group 1 was treated with amitraz at 0.025%, Group 2 was treated with lemongrass extracts at 1.36% and Group 3 with the same product at 2.72% of the plant. Engorged ticks were evaluated on animals with length superior to 4.0 mm, before (mean of days -3, -2, -1) and at 1, 2, 3, 4, 5, 6, 7 and 14 days after treatment. The mean efficacy of amitraz was 97.93%. Lemongrass extract at 2.72% reduced tick infestation by 40.3, 46.6 and 41.5% on day 3, 7 and 14 post-treatment, respectively.

  16. Use of Cymbopogon citratus essential oil in food preservation: Recent advances and future perspectives.

    Science.gov (United States)

    Ekpenyong, Christopher E; Akpan, Ernest E

    2017-08-13

    The economic burdens and health implications of food spoilage are increasing. Contamination of food sources by fungi, bacteria, yeast, nematodes, insects, and rodents remains a major public health concern. Research has focused on developing safer natural products and innovations to meet consumers' acceptance as alternatives to synthetic food preservatives. Many recent novel preservative techniques and applications of both natural and synthetic origin continue to proliferate in food and chemical industries. In particular, some essential oils of plant origin are potent food preservatives and are thus attractive alternatives to synthetic preservatives. This paper provides an overview of recent advances and future prospects in assessing the efficacy of the use of Cymbopogon citratus (lemongrass) essential oil in food preservation. The possible mechanisms of action and toxicological profile as well as evidence for or against the use of this essential oil as an alternative to synthetic food preservatives in domestic and industrial applications are discussed.

  17. Influence of agar concentration on in vitro multiplication of Cymbopogon citratus (D. C. Stapf

    Directory of Open Access Journals (Sweden)

    Ricardo J. Licea Moreno

    2001-04-01

    Full Text Available Here are presented the results on in vitro multiplication of lemon grass (Cymbopogon citratus (D. C. Stapf.; it is a very important medicinal plant because its analgesic, antinflamatory and hipotensor properties, among others, useful to elaborate several medicaments with a high popular acceptation. The main aim of this research was to set up the influence of agar concentration in culture medium during in vitro establishment on multiplication of lemon grass. Were used three treatments: (1 liquid medium with filter paper bridges, (2 3 g.l-1 of agar (BIOCEN and (3 6 g.l-1 of agar (BIOCEN. The explants were inoculated on a culture media containing Murashige and Skoog salts (1962, Heinz and Mee vitamins (1969, myoinositol 100 mg.l-1, 6-BAP 0.2 mg.l-1 and sucrose 20 g.l-1. Meristematic tips were inoculated on the treatments described above under sun light conditions, once desinfected. The explants Influence of agar concentration on in vitro multiplication of Cymbopogon citratus (D. C. Stapf. were maintained 21 days in this culture media and later it is were subcultured 5 times each 21 days, on the same multiplication culture media containing Murashige and Skoog salts (1962, tiamine 1 mg.l-1, myoinositol 100 mg.l-1, 6-BAP 0.3 mg.l-1 and sucrose 30 g.l-1. The pH was 5.7 for all culture media. The results showed the relevance of agar concentration during in vitro establishment on multiplication of lemon grass. Differences among treatments until the 2nd subculture was observed. 3.43 new axillary shoots from each explant cultured on a culture media supplemented with 3 g.l-1 of agar was reached. Key words: lemon grass, medicinal plants, micropropagation, tissue culture

  18. Cymbopogon citratus essential oil: effect on polymicrobial caries-related biofilm with low cytotoxicity.

    Science.gov (United States)

    Oliveira, Maria Alcionéia Carvalho de; Borges, Aline Chiodi; Brighenti, Fernanda Lourenção; Salvador, Marcos José; Gontijo, Aline Vidal Lacerda; Koga-Ito, Cristiane Yumi

    2017-11-06

    The objective of this study was to evaluate the effects of Cymbopogon citratus essential oil and its main compound (citral) against primary dental colonizers and caries-related species. Chemical characterization of the essential oil was performed by gas chromatography/mass spectroscopy (GC/MS), and the main compound was determined. Antimicrobial activity was tested against Actinomyces naeslundii, Lactobacillus acidophilus, S. gordonii, S. mitis, S. mutans, S. sanguinis and S. sobrinus. Minimum inhibitory and bactericide concentrations were determined by broth microdilution assay for streptococci and lactobacilli reference, and for clinical strains. The effect of the essential oil on bacterial adhesion and biofilm formation/disruption was investigated. Negative (without treatment) and positive controls (chlorhexidine) were used. The effect of citral on preformed biofilm was also tested using the same methodology. Monospecies and microcosm biofilms were tested. ANOVA or Kruskal-Wallis tests were used (α=0.05). Cytotoxicity of the essential oil to human keratinocytes was performed by MTT assay. GC/MS demonstrated one major component (citral). The essential oil showed an inhibitory effect on all tested bacterial species, including S. mutans and L. acidophilus. Essential oil of C. citratus (10X MIC) reduced the number of viable cells of lactobacilli and streptococci biofilms (p essential oil inhibited adhesion of caries-related polymicrobial biofilm to dental enamel (p essential oil showed low cytotoxicity to human keratinocytes. Based on these findings, this study can contribute to the development of new formulations for products like mouthwash, against dental biofilms.

  19. Chemical composition and insecticidal activity of Cymbopogon citratus essential oil from Cuba and Brazil against housefly

    Directory of Open Access Journals (Sweden)

    Zeneida Teixeira Pinto

    Full Text Available Essential oil of Cymbopogon citratus collected from Brazil and Cuba was tested to a chemical characterization and then was tested on the post-embryonic development of Musca domestica. The chemical composition analysis by GC-MS of the oils from Brazil/Cuba allowed the identification of 13 and 12 major constituents respectively; nine of them common to both. In the both oils, the main components were the isomers geranial and neral, which together form the compound citral. This corresponds to a total of 97.92%/Brazil and 97.69%/Cuba of the compounds identified. The monoterpene myrcene, observed only in the sample of Cuba, presented a large relative abundance (6.52%. The essential oil of C. citratus (Brazil/Cuba was dissolved in DMSO and tested at concentrations of 5, 10, 25, 50, 75 and 100% and citral was prepared by mixing 16.8 mg with 960 µL DMSO. Both essential oils and monoterpene citral were applied topically to newly-hatched larvae (1µL/larva. The results showed a lethal concentration (LC50 of 4.25 and 3.24% for the Brazilian and Cuban essential oils, respectively. Mortalities of larval and newly-hatched larvae to adult periods were dose-dependent for the two both oils as for monoterpene citral, reaching 90%. Both essential oils and citral caused morphological changes in adult specimens.

  20. Chemical composition and insecticidal activity of Cymbopogon citratus essential oil from Cuba and Brazil against housefly.

    Science.gov (United States)

    Pinto, Zeneida Teixeira; Sánchez, Félix Fernández; dos Santos, Arith Ramos; Amaral, Ana Claudia Fernandes; Ferreira, José Luiz Pinto; Escalona-Arranz, Julio César; Queiroz, Margareth Maria de Carvalho

    2015-01-01

    Essential oil of Cymbopogon citratus collected from Brazil and Cuba was tested to a chemical characterization and then was tested on the post-embryonic development of Musca domestica. The chemical composition analysis by GC-MS of the oils from Brazil/Cuba allowed the identification of 13 and 12 major constituents respectively; nine of them common to both. In the both oils, the main components were the isomers geranial and neral, which together form the compound citral. This corresponds to a total of 97.92%/Brazil and 97.69%/Cuba of the compounds identified. The monoterpene myrcene, observed only in the sample of Cuba, presented a large relative abundance (6.52%). The essential oil of C. citratus (Brazil/Cuba) was dissolved in DMSO and tested at concentrations of 5, 10, 25, 50, 75 and 100% and citral was prepared by mixing 16.8 mg with 960 µL DMSO. Both essential oils and monoterpene citral were applied topically to newly-hatched larvae (1µL/larva). The results showed a lethal concentration (LC50) of 4.25 and 3.24% for the Brazilian and Cuban essential oils, respectively. Mortalities of larval and newly-hatched larvae to adult periods were dose-dependent for the two both oils as for monoterpene citral, reaching 90%. Both essential oils and citral caused morphological changes in adult specimens.

  1. The GABAergic system contributes to the anxiolytic-like effect of essential oil from Cymbopogon citratus (lemongrass).

    Science.gov (United States)

    Costa, Celso A Rodrigues de Almeida; Kohn, Daniele Oliveira; de Lima, Valéria Martins; Gargano, André Costa; Flório, Jorge Camilo; Costa, Mirtes

    2011-09-01

    The essential oil (EO) from Cymbopogon citratus (DC) Stapf is reported to have a wide range of biological activities and is widely used in traditional medicine as an infusion or decoction. However, despite this widely use, there are few controlled studies confirming its biological activity in central nervous system. The anxiolytic-like activity of the EO was investigated in light/dark box (LDB) and marble-burying test (MBT) and the antidepressant activity was investigated in forced-swimming test (FST) in mice. Flumazenil, a competitive antagonist of benzodiazepine binding and the selective 5-HT(1A) receptor antagonist WAY100635 was used in experimental procedures to determine the action mechanism of EO. To exclude any false positive results in experimental procedures, mice were submitted to the rota-rod test. We also quantified some neurotransmitters at specific brain regions after EO oral acute treatment. The present work found anxiolytic-like activity of the EO at the dose of 10mg/kg in a LDB. Flumazenil, but not WAY100635, was able to reverse the effect of the EO in the LDB, indicating that the EO activity occurs via the GABA(A) receptor-benzodiazepine complex. Only at higher doses did the EO potentiate diethyl-ether-induced sleeping time in mice. In the FST and MBT, EO showed no effect. Finally, the increase in time spent in the light chamber, demonstrated by concomitant treatment with ineffective doses of diazepam (DZP) and the EO, revealed a synergistic effect of the two compounds. The lack of activity after long-term treatment in the LDB test might be related to tolerance induction, even in the DZP-treated group. Furthermore, there were no significant differences between groups after either acute or repeated treatments with the EO in the rota-rod test. Neurochemical evaluation showed no amendments in neurotransmitter levels evaluated in cortex, striatum, pons, and hypothalamus. The results corroborate the use of Cymbopogon citratus in folk medicine and

  2. Cymbopogon citratus essential oil: effect on polymicrobial caries-related biofilm with low cytotoxicity

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    Maria Alcionéia Carvalho de OLIVEIRA

    2017-11-01

    Full Text Available Abstract The objective of this study was to evaluate the effects of Cymbopogon citratus essential oil and its main compound (citral against primary dental colonizers and caries-related species. Chemical characterization of the essential oil was performed by gas chromatography/mass spectroscopy (GC/MS, and the main compound was determined. Antimicrobial activity was tested against Actinomyces naeslundii, Lactobacillus acidophilus, S. gordonii, S. mitis, S. mutans, S. sanguinis and S. sobrinus. Minimum inhibitory and bactericide concentrations were determined by broth microdilution assay for streptococci and lactobacilli reference, and for clinical strains. The effect of the essential oil on bacterial adhesion and biofilm formation/disruption was investigated. Negative (without treatment and positive controls (chlorhexidine were used. The effect of citral on preformed biofilm was also tested using the same methodology. Monospecies and microcosm biofilms were tested. ANOVA or Kruskal-Wallis tests were used (α=0.05. Cytotoxicity of the essential oil to human keratinocytes was performed by MTT assay. GC/MS demonstrated one major component (citral. The essential oil showed an inhibitory effect on all tested bacterial species, including S. mutans and L. acidophilus. Essential oil of C. citratus (10X MIC reduced the number of viable cells of lactobacilli and streptococci biofilms (p < 0.05. The essential oil inhibited adhesion of caries-related polymicrobial biofilm to dental enamel (p < 0.01. Citral significantly reduced the number of viable cells of streptococci biofilm (p < 0.001. The essential oil showed low cytotoxicity to human keratinocytes. Based on these findings, this study can contribute to the development of new formulations for products like mouthwash, against dental biofilms.

  3. Scaling-up the biomass production of Cymbopogon citratus L. in temporary immersion system

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    Elisa Quiala

    2014-04-01

    Full Text Available Shoot-tips, collected from greenhouse-grown plants of Cymbopogon citratus L. (lemmon grass, were incubated on a semi-solid Murashige and Skoog (MS medium with 30% (w/v sucrose, and supplemented with 0.89 µM 6-benzyladenine (BA. After three weeks of culture shoots were individualized and then inoculated in 10 litres temporary immersion system (TIS containing 3 litres of the same basal MS liquid medium. The effects of three immersion frequency (immersion every 12, 6 and 4 hours on the production of biomass were studied. Three inoculum densities (forty, fifty and sixty shoots/TIS were also tested. The biomass growth was inûuenced by the immersion frequency. The highest proliferation rate (17.3 shoots/explants and the plant length (45.2 cm were obtained in plants immersed every 4 h. Also, the fresh and dry biomass weight (153.4 gFW and 24.8 gDW, respectively were higher in this treatment. The maximum biomass accumulation (185.2 gFW and 35.2 gDW was achieved after 30 days of culture when an inoculum density of 60 explants per TIS was used. For the first time, biomass of C. citratus has been produced in10 litres TIS. These results represent the first step in the scaling-up the biomass production of this medicinal plant in large temporary immersion bioreactors. Key words: automation, biomass growth, lemmon grass medicinal plant, tissue culture

  4. Acaricidal activity of Cymbopogon citratus and Azadirachta indica against house dust mites.

    Science.gov (United States)

    Hanifah, Azima Laili; Awang, Siti Hazar; Ming, Ho Tze; Abidin, Suhaili Zainal; Omar, Maizatul Hashima

    2011-10-01

    To examine the acaricidal effects of the essential oil of Cymbopogon citratus leaf extract (lemongrass) and ethanolic Azadirachta indica leaf extract (neem) against house dust mites Dermatophagoides farinae (D. farinae) and Dermatophagoides pteronyssinus (D. pteronyssinus). Twenty-five adults mites were placed onto treated filter paper that is soaked with plant extract and been tested at different concentrations (50.00%, 25.00%, 12.50%, 6.25% and 3.13%) and exposure times (24hrs, 48hrs, 72hrs and 96 hrs). All treatments were replicated 7 times, and the experiment repeated once. The topical and contact activities of the two herbs were investigated. Mortalities from lemongrass extract were higher than neem for both topical and contact activities. At 50 % concentration, both 24 hrs topical and contact exposures to lemongrass resulted in more than 91% mortalities for both species of mites. At the same concentration and exposure time, neem resulted in topical mortalities of 40.3% and 15.7% against D. pteronyssinus and D. farinae respectively; contact mortalities were 8.0% and 8.9% against the 2 mites, respectively. There was no difference in topical mortalities of D. pteronyssinus from exposure to concentrations of lemongrass and neem up to 12.50%; lemongrass was more effective than neem at the higher concentrations. Generally, topical mortalities of D. farinae due to lemongrass are higher than that due to neem. Contact mortalities of lemongrass are always higher that neem against both species of mites.

  5. Cymbopogon citratus industrial waste as a potential source of bioactive compounds.

    Science.gov (United States)

    Tavares, Filipa; Costa, Gustavo; Francisco, Vera; Liberal, Joana; Figueirinha, Artur; Lopes, Maria Celeste; Cruz, Maria Teresa; Batista, Maria Teresa

    2015-10-01

    Cymbopogon citratus (Cc), commonly known as lemongrass, is a very important crop worldwide, being grown in tropical countries. It is widely used in the food, pharmaceutical, cosmetic and perfumery industries for its essential oil. Cc aqueous extracts are also used in traditional medicine. They contain high levels of polyphenols, which are known for their antioxidant and anti-inflammatory properties. Hydrodistillation of lemongrass essential oil produces an aqueous waste (CcHD) which is discarded. Therefore a comparative study between CcHD and Cc infusion (CcI) was performed to characterize its phytochemical profile and to research its antioxidant and anti-inflammatory potential. HPLC-PDA/ESI-MS(n) analysis showed that CcI and CcHD have similar phenolic profiles, with CcHD presenting a higher amount of polyphenols. Additionally, both CcI and CcHD showed antioxidant activity against DPPH (EC50 of 41.72 ± 0.05 and 42.29 ± 0.05 µg mL(-1) respectively) and strong anti-inflammatory properties, by reducing NO production and iNOS expression in macrophages and through their NO-scavenging activity, in a dose-dependent manner. Furthermore, no cytotoxicity was observed. The data of this study encourage considering the aqueous solution from Cc leaf hydrodistillation as a source of bioactive compounds, which may add great industrial value to this crop. © 2014 Society of Chemical Industry.

  6. Optimized extraction of polysaccharides from Cymbopogon citratus and its biological activities.

    Science.gov (United States)

    Thangam, Ramar; Suresh, Veeraperumal; Kannan, Soundarapandian

    2014-04-01

    In this study the extraction of hot water soluble polysaccharides (HWSPs) from Cymbopogon citratus using hot water decoction was discussed. Response surface methodology (RSM) based on a three level, three variable central composite rotatable design (CCRD), was employed to obtain best possible combination of extraction time (X1: 30-180 min), extraction temperature (X2: 70-100 °C) and water to the raw material ratio (X3: 10-60) for maximum HWSPs extraction. The optimum extraction conditions were as follows: extraction time was around 113.81 min, extraction temperature at 99.66 °C and the ratio of water to raw material was 33.11 g/mL. Under these conditions, the experimental yield was 13.24±0.23%, which is well in close agreement with the value predicted by RSM model yield (13.19%). The basic characterization of HWSPs was determined by using the FTIR. These preliminary in vitro biological studies indicated that lemongrass polysaccharides were useful for anticancer therapy. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Protective Effect of Cymbopogon citratus Essential Oil in Experimental Model of Acetaminophen-Induced Liver Injury.

    Science.gov (United States)

    Uchida, Nancy Sayuri; Silva-Filho, Saulo Euclides; Aguiar, Rafael Pazinatto; Wiirzler, Luiz Alexandre Marques; Cardia, Gabriel Fernando Esteves; Cavalcante, Heitor Augusto Otaviano; Silva-Comar, Francielli Maria de Souza; Becker, Tânia Cristina Alexandrino; Silva, Expedito Leite; Bersani-Amado, Ciomar Aparecida; Cuman, Roberto Kenji Nakamura

    2017-01-01

    To investigate the hepatoprotective effect of Cymbopogon citratus or lemongrass essential oil (LGO), it was used in an animal model of acute liver injury induced by acetaminophen (APAP). Swiss mice were pretreated with LGO (125, 250 and 500[Formula: see text]mg/kg) and SLM (standard drug, 200[Formula: see text]mg/kg) for a duration of seven days, followed by the induction of hepatotoxicity of APAP (single dose, 250[Formula: see text]mg/kg). The liver function markers alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and gamma-glutamyl transferase were determined to evaluate the hepatoprotective effects of the LGO. The livers were used to determine myeloperoxidase (MPO) activity, nitric oxide (NO) production and histological analysis. The effect of LGO on leukocyte migration was evaluated in vitro. Anti-oxidant activity was performed by assessing the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) in vitro. LGO pretreatment decreased significantly the levels of ALT, AST and ALP compared with APAP group. MPO activity and NO production were decreased. The histopathological analysis showed an improved of hepatic lesions in mice after LGO pretreatment. LGO inhibited neutrophil migration and exhibited anti-oxidant activity. Our results suggest that LGO has protective activity against liver toxicity induced by paracetamol.

  8. Effects of essential oil from Cymbopogon citratus leaves and its susceptibility on the quality of fresh orange juice during storage

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    Euloge Adjou

    2017-03-01

    Full Text Available The present study aims to evaluate the effect of essential oil (EO from Cymbopogon citratus leaves against the spoilage flora of fresh orange juice. Thus, the EO was extracted by hydrodistillation from fresh leaves of Cymbopogon citratus collected in southern Benin and its chemical composition was determined by gas chromatography, coupled to mass spectrometry (GC/MS. Orange samples were collected from large production areas of South and Central Benin and juices were extracted by mechanical pressing. After identification of spoilage flora of fresh orange juice, antimicrobial tests were carried out with the EO of Cymbopogon citratus to evaluate its antimicrobial activity on spoilage flora of fresh orange juice.  Results indicate that the spoilage flora of fresh orange juice is mainly composed of fungi belonging to the genera of Cladosporium, Penicillium and Fusarium. Bacteria such as Enterobacter cloacae and Enterobacter aerogenes were also identified in some samples. The major compounds identified in the EO by GC/MS are Neral (33.0% and geranial (41.3% with a predominance of oxygenated monoterpenes (85.5%. Antimicrobial tests have revealed a high antibacterial activity of the EO, with minimum bactericidal concentrations (MBC between 0.1 and 0.15 μL.mL-1. Antifungal tests revealed that fungi are also susceptible to this EO with minimum fungicidal concentration (MFC between 0.15 and 0.25 μL.mL-1. Results obtained during the evaluation of the physicochemical characteristics of the orange juice stored by adding EO, indicated a significant decrease in the pH and vitamin C content. However, with EO concentration of 0.250 μL.mL-1, the pH of stored juice was 6.4 ± 0.1 after 15 days of preservation, with a best vitamin C content of 28.06 ± 0.03 mg / 100mL. The EO of Cymbopogon citratus, with high antimicrobial activity, could be used as an alternative in the preservation of fruit juices, replacing antimicrobials from chemical synthesis.

  9. Broiler Pre-Slaughter Water Diet with Grass Lemongrass (Cymbopogon Citratus Stapf

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    RG Garcia

    Full Text Available ABSTRACT The pre-slaughter management is one of the predisposing factors to the reduction in the quality of the carcass and broiler meat, mainly for being a stressful condition. This study evaluates the inclusion of lemongrass (Cymbopogon citratus Stapf in the water used in the diet of pre-slaughter broilers for the first time. The carcass and meat quality parameters were evaluated. The experiment was carried out in the poultry production of an experimental sector of the Federal University of Grande Dourados - UFGD. A total of 2,594 broilers were distributed in an entirely randomized design in a factorial arrangement of 3x2x2, with three different lemongrass concentrations in the form of infusion (0. 1 and 5 g/L, two sexes and two genetic strains (Ross 308® and Cobb 500®, and with four replications. After 42 days, 144 broilers were slaughtered, and the quality parameters of carcass and meat were evaluated. A higher incidence of scratches and higher water retention capacity were found in Ross 308® male (p<0.05. Less exudate of breast fillets loss was observed in broiler Ross 308® males 72 h post-mortem (p<0.05. There was an interaction between sex and lemongrass levels in the drinking water of the broilers in the sensory analysis of meat (p<0.05, more preferably of chewiness and juiciness for males undergoing free diet for juiciness and lemongrass in the female diet with 5g/L. The use of lemongrass infusions in pre-slaughter did not bring considerable benefits to the quality of carcass and meat of broiler.

  10. Antimicrobial constituents and synergism effect of the essential oils from Cymbopogon citratus and Alpinia galanga.

    Science.gov (United States)

    Tadtong, Sarin; Watthanachaiyingcharoen, Rith; Kamkaen, Narisa

    2014-02-01

    From the fresh leaf sheathes of lemongrass (Cymbopogon citratus) and rhizomes of galanga (Alpinia galanga) light yellow and colorless oils, respectively, were obtained by hydrodistillation and microwave assisted extraction (MAE) in yields of 0.24% and 0.03%, and 0.11% and trace (w/w), respectively. By GC/MS analysis, five major constituents were identified in lemongrass oil, E-citral, Z-citral, beta-myrcene, selina-6-en-4-ol, and cis-ocimene, and five in galanga oil, 1,8-cineole, phenol 4-(2-propenyl)-acetate, dl-limonene, alpha-pinene, and a-terpineol. Three major components of the combined lemongrass and galanga oils (ratio 7:3, 1:1, 3:7) were 1,8-cineole (46.3%, 31.5%, 19.3%), E-citral (12.8%, 22.7%, 32.8%) and Z-citral (8.5%, 15.2%, 21.6%). The MICs of lemongrass and galanga oils were: against Staphylococcus aureus 0.5% and 4%, v/v, against Pseudomonas aeruginosa 40% and >40%,v/v, against Streptococcus bovis 0.25% and 0.5%, v/v, and against Candida albicans 0.25% and 0.5%, v/v. Citral (from lemongrass oil) gave greater potentiation than 1,8-cineole (from galanga oil). The combination profiles of galanga oil with lemongrass oil (volume ratios 3:7, 1:1, and 7:3) were tested against the four pathogenic microorganisms. Synergistic activity was best noted for only one ratio (volume ratio 3:7) as the sigmafic< 1 against all tested microorganisms. The present investigation provides evidenc that the utilization of two essential oils in combination should be assessed for synergistic antimicrobial activity in order to reduce their minimum effective dose.

  11. Toxicity of lemon grass Cymbopogon citratus powder and methanol extract against rice weevil Sitophilus oryzae (Coleoptera: Curculionidae

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    Martin Osaigbokan Uwamose

    2017-03-01

    Full Text Available Objective: To evaluate the toxicity potential of lemon grass [Cymbopogon citratus (C. citratus] products against adult rice weevil, Sitophilus oryzae. Methods: Lemon grass (C. citratus leaves were sundried for 7 days, pulverized and sieved using 0.5 mm mesh size to obtain fine powders. About 500 g of the powder were dissolved in 1000 mL of 90% methanol to produce the extract. The powder and extract were used for the bioassay. The powder was tested at 1.0, 1.5, 2.0 and 2.5 g/10 g rice grains, respectively. The toxic potential of the extract of concentration of 1.0, 1.5, 2.0, and 2.5 mg/mL were evaluated using the filter paper method. The experiment was setup on a completely randomized design using three replicates per treatment. Results: The results indicated significant difference (F = 7.450; df = 3.15; P < 0.05 in mean percentage mortality after 24, 48, 72, and 96 h exposure with the powder compared with the control. Significantly (F = 5.519; df = 3.15; P < 0.05 higher percentage adult mortality was also observed in the extract after 24, 48, 72, and 96 h exposure compared with the control. The LC50 value of the powder was 4.91 g/10 g of rice while the LT50 was 160.51 h. The LC50 value of the extract was 2.16 mg/20 mL of methanol with an LT50 of 75.10 h. The methanol extract of C. citratus showed the highest mortality compared to the powder which was less toxic. Conclusions: The study showed that C. citratus products are promising insecticides and can be used effectively in the management of Sitophilus oryzae in storage..

  12. Anticancer Effect and Apoptosis Induction of Cymbopogon citratus Plant on Head and Neck HTB43 Cancer Cell Lines

    International Nuclear Information System (INIS)

    Yen, N.; Zainah Adam; Arapoc, D.J.; Mohamed Zaffar Ali Mohamed Amiroudine; Shafii Khamis

    2016-01-01

    Lemongrass (Cymbopogon citratus) is a major crop in Asia, South and Central America, Africa and other tropical countries. It is commonly used as a culinary herb in Asian cuisine and also as medicinal herb in India. The objective of the present study was to investigate the anticancer effect of Cymbopogon citratus essential oil on human head and neck cancer cell lines. Lemongrass essential oil was obtained from fresh lemongrass leaves using the microwave extractor. The yield of the highly purified oil obtained was 0.62 %. The oil was investigated for its in-vitro cytotoxicity and apoptosis induction against human head and neck HTB43 cancer cell lines. The results showed promising cytotoxic effects with IC_5_0 value of 15.42 ± 6.10 μg/ ml (HTB43) respectively. In addition, the essential oil has found inducing apoptotic effect within HTB43 cells (25.71 ± 1.43 %). These preliminary results indicated that the oil had apoptosis-based cytotoxicity against head and neck cancer cells. However, further investigations need to be carried out in order to elucidate the anti-cancer properties of the oil. The phytochemicals properties of the active compounds found in the oil also need to be studied. (author)

  13. In vitro antimicrobial properties of plant essential oils thymus vulgaris, cymbopogon citratus and laurus nobilis against five important foodborne pathogens

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    Alessandra Farias Millezi

    2012-03-01

    Full Text Available Several essential oils of condiment and medicinal plants possess proven antimicrobial activity and are of important interest for the food industry. Therefore, the Minimum Inhibitory Concentrations (MIC of those oils should be determined for various bacteria. MIC varies according to the oil used, the major compounds, and the physiology of the bacterium under study. In the present study, the essential oils of the plants Thymus vulgaris (time, Cymbopogon citratus (lemongrass and Laurus nobilis (bay were chemically quantified, and the MIC was determined on the bacteria Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Listeria monocytogenes ATCC 19117, Salmonella enterica Enteritidis S64, and Pseudomonas aeruginosa ATCC 27853. The essential oil of C. citratus demonstrated bacterial activity at all concentrations tested and against all of the bacteria tested. The majority of essential oil compounds were geranial and neral. The major constituent of T. vulgaris was 1.8-cineol and of L. nobilis was linalool, which presented lower antibacterial activity, followed by 1.8-cineol. The Gram-negative bacteria demonstrated higher resistance to the use of the essential oils tested in this study. E. coli was the least sensitive and was inhibited only by the oils of C. citratus and L. nobilis.

  14. Effect of Lippia alba and Cymbopogon citratus essential oils on biofilms of Streptococcus mutans and cytotoxicity in CHO cells.

    Science.gov (United States)

    Tofiño-Rivera, A; Ortega-Cuadros, M; Galvis-Pareja, D; Jiménez-Rios, H; Merini, L J; Martínez-Pabón, M C

    2016-12-24

    Caries is a public health problem, given that it prevails in 60 to 90% of the school-age global population. Multiple factors interact in its etiology, among them dental plaque is necessary to have lactic acid producing microorganisms like Streptococcus from he Mutans group. Existing prevention and treatment measures are not totally effective and generate adverse effects, which is why it is necessary to search for complementary strategies for their management. The study sought to evaluate the eradication capacity of Streptococcus mutans biofilms and the toxicity on eukaryotic cells of Lippia alba and Cymbopogon citratus essential oils. Essential oils were extracted from plant material through steam distillation and then its chemical composition was determined. The MBEC-high-throughput (MBEC-HTP) (Innovotech, Edmonton, Alberta, Canada) assay used to determine the eradication concentration of S. mutans ATCC 35668 strain biofilms. Cytotoxicity was evaluated on CHO cells through the MTT cell proliferation assay. The major components in both oils were Geraniol and Citral; in L. alba 18.9% and 15.9%, respectively, and in C. citratus 31.3% and 26.7%. The L. alba essential oils presented eradication activity against S. mutans biofilms of 95.8% in 0.01mg/dL concentration and C. citratus essential oils showed said eradication activity of 95.4% at 0.1, 0.01mg/dL concentrations and of 93.1% in the 0.001mg/dL concentration; none of the concentrations of both essential oils showed toxicity on CHO cells during 24h. The L. alba and C. citratus essential oils showed eradication activity against S. mutans biofilms and null cytotoxicity, evidencing the need to conduct further studies that can identify their active components and in order to guide a safe use in treating and preventing dental caries. Copyright © 2016 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

  15. [Anti-Candida albicans activity of essential oils including Lemongrass (Cymbopogon citratus) oil and its component, citral].

    Science.gov (United States)

    Abe, Shigeru; Sato, Yuichi; Inoue, Shigeharu; Ishibashi, Hiroko; Maruyama, Naho; Takizawa, Toshio; Oshima, Haruyuki; Yamaguchi, Hideyo

    2003-01-01

    The effects of 12 essential oils, popularly used as antifungal treatments in aromatherapy, on growth of Candida albicans were investigated. Mycelial growth of C. albicans, which is known to give the fungus the capacity to invade mucosal tissues, was inhibited in the medium containing 100 micro g/ml of the oils: lemongrass (Cymbopogon citratus), thyme (Thymus vulgaris), patchouli (Pogostemon cablin) and cedarwood (Cedrus atlantica). Not only lemongrass oil but also citral, a major component of lemongrass oil (80%), in the range of 25 and 200 micro g/ml inhibited the mycelial growth but allowed yeast-form growth. More than 200 micro g/ml of citral clearly inhibited both mycelial and yeast-form growth of C. albicans. These results provide experimental evidence suggesting the potential value of lemongrass oil for the treatment of oral or vaginal candidiasis.

  16. Laboratory Study of The Effect of Lemongrass Leaves Cymbopogon citratus on An Onion Thrips Insect Thrips tabaci (Thripidae: Thysanoptera

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    Ather A. Mohsin

    2018-03-01

    Full Text Available This laboratory study was carried out to test the effect of the extracts of ethanol, chloroform, volatile oil and emulsifier of Cymbopogon citratus in killing the adults of the thrips tabaci. The concentrations 250, 500 and 1000 ppm. The results showed that the highest percentage of killed in Volatile oil with a concentration of 1000 ppm at 60.00, 63.33, 66.66, 70 and 76.66% for the first, second, third, fifth and seventh days of control and the lowest percentage was for the emulsifier at 30.00, 36.66, 46.66, 53.33 and 63.33% for the first and second, third, fifth and seventh days of the control, respectively, and we noticed that the higher the concentrations, the higher the percentage of killings and the increase in the percentage of killings cumulatively, as it was the highest percentage of killing on the seventh day.

  17. Repellent effects of the essential oils of Cymbopogon citratus and Tagetes minuta on the sandfly, Phlebotomus duboscqi.

    Science.gov (United States)

    Kimutai, Albert; Ngeiywa, Moses; Mulaa, Margaret; Njagi, Peter G N; Ingonga, Johnstone; Nyamwamu, Lydia B; Ombati, Cyprian; Ngumbi, Philip

    2017-02-15

    The sandfly, Phlebotomus duboscqi is a vector of zoonotic cutaneous leishmaniasis (ZCL) that is an important public health problem in Eastern Africa. Repellents have been used for protection of humans against vectors of ZCL and other vectors that transmit killer diseases including malaria, Rift Valley fever, dengue, and yellow fever. The repellent effects of different doses of the essential oils from the lemon grass, Cymbopogon citratus and Mexican marigold, Tagetes minuta were evaluated in a two-chamber bioassay against 3- to 7-day-old unfed females of P. duboscqi in the laboratory. The results were compared with those that were obtained when test animals were treated with an equivalent dose of diethyl-3-methylbenzamide, which is a repellent that is commonly used as a positive control. Overall, percentage repellency increased with increasing doses of the essential oils while biting rates decreased with increasing concentrations of the oils. Further, the oil of C. citratus was more potent than that of T. minuta with regard to protection time and biting deterrence. The effective doses at 50% (ED 50 ) and at 90% (ED 90 ) for the oil of C. citratus, were 0.04 and 0.79 mg/ml, respectively. Those of the oil of T. minuta were 0.10 and 12.58 mg/ml. In addition, the percentage repellency of 1 mg/ml of the essential oils of C. citratus and T. minuta against sandflies was 100% and 88.89%, respectively. A lower dose of 0.5 mg/ml of the oils, elicited 89.13% repellency for C. citratus and 52.22% for T. minuta. The laboratory tests showed that the essential oils of the two plants were highly repellent to adult sand flies, P. duboscqi. Thus, the two essential oils are candidate natural repellents that can be used against P. duboscqi due to their high efficacy at very low doses, hence, the envisaged safety in their use over chemical repellents. It remains to carry out clinical studies on human subjects with appropriate formulations of the oils prior to recommending their

  18. Essential oil of Cymbopogon citratus (lemongrass) and geraniol, but not citral, promote gastric healing activity in mice.

    Science.gov (United States)

    Venzon, Larissa; Mariano, Luísa Nathália Bolda; Somensi, Lincon Bordignon; Boeing, Thaise; de Souza, Priscila; Wagner, Theodoro Marcel; Andrade, Sérgio Faloni de; Nesello, Luciane Angela Nottar; da Silva, Luísa Mota

    2018-02-01

    Cymbopogon citratus, popularly known as lemongrass, is used for the treatment of gastric, nervous and hypertensive disorders, in addition to its use in the food and pharmaceutical industries. This study evaluated the gastroprotective and gastric healing effect of essential oil of C. citratus (EOCC), citral and geraniol at doses of 1-100 mg/kg (p.o) on acute ethanol-induced ulcer and chronic acetic acid-induced ulcer. Histological and histochemical evaluation was also performed, as well as the in vitro evaluation of the effects of these phytochemicals on H + /K + -ATPase activity. In the ethanol-induced gastric ulcer, the minimum effective oral dose of EOCC, citral and geraniol were 10, 100 and 3 mg/kg, reducing the ulcer area by 51.67%, 96.57% and 55.74%, respectively, compared to vehicle group (25.82 ± 3.59 mm 2 ). Moreover, EOCC (10 mg/kg, p.o) and geraniol (3 mg/kg), but not citral (100 mg/kg), accelerated the gastric healing process by 34.52 and 80.57%, compared to acetic-acid ulcerated group treated with vehicle (36.04 ± 1.03 mm 2 ). These healing effects were confirmed histologically by the contraction of the ulcer base and by the enhancement on mucin staining in slices of ulcer site from mice treated with EOCC or geraniol. Interestingly, EOCC and citral at 100 μg/ml inhibited the H + / K + -ATPase activity by 28.26% and 44.36%, whereas geraniol did not change this parameter. Together, these findings confirm the gastroprotective and healing gastric ulcer effects of essential oil from aerial parts of C. citratus and added the information that geraniol, but not citral, promotes healing effects on installed ulcers. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  19. Cymbopogon citratus-synthesized gold nanoparticles boost the predation efficiency of copepod Mesocyclops aspericornis against malaria and dengue mosquitoes.

    Science.gov (United States)

    Murugan, Kadarkarai; Benelli, Giovanni; Panneerselvam, Chellasamy; Subramaniam, Jayapal; Jeyalalitha, Tirupathi; Dinesh, Devakumar; Nicoletti, Marcello; Hwang, Jiang-Shiou; Suresh, Udaiyan; Madhiyazhagan, Pari

    2015-06-01

    Plant-borne compounds can be employed to synthesize mosquitocidal nanoparticles that are effective at low doses. However, how they affect the activity of mosquito predators in the aquatic environment is unknown. In this study, we synthesized gold nanoparticles (AuN) using the leaf extract of Cymbopogon citratus, which acted as a reducing and capping agent. AuN were characterized by a variety of biophysical methods and sorted for size in order to confirm structural integrity. C. citratus extract and biosynthesized AuN were tested against larvae and pupae of the malaria vector Anopheles stephensi and the dengue vector Aedes aegypti. LC₅₀ of C. citratus extract ranged from 219.32 ppm to 471.36 ppm. LC₅₀ of AuN ranged from 18.80 ppm to 41.52 ppm. In laboratory, the predatory efficiency of the cyclopoid crustacean Mesocyclops aspericornis against A. stephensi larvae was 26.8% (larva I) and 17% (larva II), while against A. aegypti was 56% (I) and 35.1% (II). Predation against late-instar larvae was minimal. In AuN-contaminated environment,predation efficiency against A. stephensi was 45.6% (I) and 26.7% (II), while against A. aegypti was 77.3% (I) and 51.6% (II). Overall, low doses of AuN may help to boost the control of Anopheles and Aedes larval populations in copepod-based control programs. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. The use of powder and essential oil of Cymbopogon citratus against mould deterioration and aflatoxin contamination of "egusi" melon seeds.

    Science.gov (United States)

    Bankole, S A; Joda, A O; Ashidi, J S

    2005-01-01

    Experiments were carried out to determine the potential of using the powder and essential oil from dried ground leaves of Cymbopogon citratus (lemon grass) to control storage deterioration and aflatoxin contamination of melon seeds. Four mould species: Aspergillus flavus, A. niger, A. tamarii and Penicillium citrinum were inoculated in the form of conidia suspension (approx. 10(6) conidia per ml) unto shelled melon seeds. The powdered dry leaves and essential oil from lemon grass were mixed with the inoculated seeds at levels ranging from 1-10 g/100 g seeds and 0.1 to 1.0 ml/100 g seeds respectively. The ground leaves significantly reduced the extent of deterioration in melon seeds inoculated with different fungi compared to the untreated inoculated seeds. The essential oil at 0.1 and 0.25 ml/100 g seeds and ground leaves at 10 g/100 g seeds significantly reduced deterioration and aflatoxin production in shelled melon seeds inoculated with toxigenic A. flavus. At higher dosages (0.5 and 1.0 ml/100 g seeds), the essential oil completely prevented aflatoxin production. After 6 months in farmers' stores, unshelled melon seeds treated with 0.5 ml/ 100 g seeds of essential oil and 10 g/100 g seeds of powdered leaves of C. citratus had significantly lower proportion of visibly diseased seeds and Aspergillus spp. infestation levels and significantly higher seed germination compared to the untreated seeds. The oil content, free fatty acid and peroxide values in seeds protected with essential oil after 6 months did not significantly differ from the values in seeds before storage. The efficacy of the essential oil in preserving the quality of melon seeds in stores was statistically at par with that of fungicide (iprodione) treatment. ((c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).

  1. Efecto del aceite esencial de Cymbopogon citratus sobre propiedades fisicoquímicas en películas de quitosano

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    María del Carmen Vázquez - Briones

    2017-01-01

    Full Text Available Se investigó el efecto de la incorporación de aceite esencial de zacate limón ( Cymbopogon citratus , en concentraciones de 0, 200 y 400 ppm, en las propiedades fisicoquímicas (espesor, humedad, solubilidad, permeabilidad al vapor de agua, color, transparencia y mecánicas (resistencia a la tensión y elongación de películas de quitosano a dos concentraciones (1 y 3%. Los resultados mostraron un efecto significativo (p ≤ 0,05 en los valores del espesor de las películas a las dos concentraciones de quitosano. Se observó un efecto significativo (p ≤ 0,05 en los valores de humedad a concentraciones de 0, 200 y 400 ppm de aceite esencial. La adición de aceite esencial en películas de quitosano mostró un efecto significativo (p ≤ 0,05 en los valores de permeabili dad al vapor de agua. La concentración de quitosano mostró un efecto significativo (p ≤ 0,05 en transparencia y en los parámetros de color L* , a* , b* . Al variar la concentración de quitosano se observó un incremento significativo (p ≤ 0,05 en los valores de resistencia a la tensión de las películas de quitosano.

  2. Protective effects of lemongrass (Cymbopogon citratus STAPF) essential oil on DNA damage and carcinogenesis in female Balb/C mice.

    Science.gov (United States)

    Bidinotto, Lucas T; Costa, Celso A R A; Salvadori, Daisy M F; Costa, Mirtes; Rodrigues, Maria A M; Barbisan, Luís F

    2011-08-01

    This study investigated the protective effect of oral treatment with lemongrass (Cymbopogon citratus STAPF) essential oil (LGEO) on leukocyte DNA damage induced by N-methyl-N-nitrosurea (MNU). Also, the anticarcinogenic activity of LGEO was investigated in a multi-organ carcinogenesis bioassay induced by 7,12-dimethylbenz(a)antracene, 1,2-dimethylhydrazine and N-butyl-N-(4-hydroxibuthyl)nitrosamine in Balb/C female Balb/c mice (DDB-initiated mice). In the short-term study, the animals were allocated into three groups: vehicle group (negative control), MNU group (positive control) and LGEO 500 mg kg⁻¹ (five times per week for 5 weeks) plus MNU group (test group). Blood samples were collected to analyze leukocyte DNA damage by comet assay 4 h after each MNU application at the end of weeks 3 and 5. The LGEO 500 mg kg⁻¹ treated group showed significantly lower (P lemongrass essential oil provided protective action against MNU-induced DNA damage and a potential anticarcinogenic activity against mammary carcinogenesis in DDB-initiated female Balb/C mice. Copyright © 2010 John Wiley & Sons, Ltd.

  3. Inhibitory effect of three C-glycosylflavonoids from Cymbopogon citratus (Lemongrass) on human low density lipoprotein oxidation.

    Science.gov (United States)

    Orrego, Roxana; Leiva, Elba; Cheel, José

    2009-09-30

    This study assessed the inhibitory effect of three C-glycosylflavonoids from Cymbopogon citratus leaves--isoorientin (1), swertiajaponin (2) and isoorientin 2"-Orhamnoside (3)--on human LDL oxidation. Isolated LDL was incubated with compounds 1-3 and the kinetics of lipid peroxidation were assessed by conjugated diene and malondialdehyde-thiobarbituric acid reactive substances (MDA-TBARS) formation after addition of copper ions. Significant differences (p < 0.05) between the lag time phase of the control and the lag time phase in the presence of the compounds 1 (0.25 microM) and 2 (0.50 microM) were observed. After five hours of incubation all three compounds showed a significant inhibitory effect on MDA-TBARS formation with respect to the control. After six hours of incubation only compound 1 kept a remarkable antioxidant effect. This study demonstrates that isoorientin (1) is an effective inhibitor of in vitro LDL oxidation. As oxidative damage to LDL is a key event in the formation of atherosclerotic lesions, the use of this natural antioxidant may be beneficial to prevent or attenuate atherosclerosis.

  4. A novel ionic amphiphilic chitosan derivative as a stabilizer of nanoemulsions: Improvement of antimicrobial activity of Cymbopogon citratus essential oil.

    Science.gov (United States)

    Bonferoni, Maria Cristina; Sandri, Giuseppina; Rossi, Silvia; Usai, Donatella; Liakos, Ioannis; Garzoni, Alice; Fiamma, Maura; Zanetti, Stefania; Athanassiou, Athanassia; Caramella, Carla; Ferrari, Franca

    2017-04-01

    Amphiphilic chitosans have been recently proposed to improve delivery of poorly soluble drugs. In the present paper a derivative obtained by ionic interaction between chitosan and oleic acid was for the first time studied to physically stabilize o/w nanoemulsions of an antimicrobial essential oil, Cymbopogon citratus (Lemongrass), in a low energy and mild conditions emulsification process. The novel combination of spontaneous emulsification process with chitosan oleate amphiphilic properties resulted in a stable dispersion of a few hundred nanometer droplets. Positive zeta potential confirmed the presence of a chitosan shell around the oil droplets, which is responsible for the nanoemulsion physical stabilization and for the maintenance of chitosan bioactive properties, such as mucoadhesion. Cytotoxicity test was performed on four different cell lines (HEp-2, Caco-2, WKD and McCoy cells) showing biocompatibility of the system. The maintenance and in some cases even a clear improvement in the essential oil antimicrobial activity towards nine bacterial and ten fungal strains, all of clinical relevance was verified for Lemongrass nanoemulsion. Copyright © 2017. Published by Elsevier B.V.

  5. Flavan hetero-dimers in the Cymbopogon citratus infusion tannin fraction and their contribution to the antioxidant activity.

    Science.gov (United States)

    Costa, Gustavo; González-Manzano, Susana; González-Paramás, Ana; Figueiredo, Isabel Vitória; Santos-Buelga, Celestino; Batista, Maria Teresa

    2015-03-01

    Cymbopogon citratus (lemongrass) leaf infusion, a commonly used ingredient in Asian, African and Latin American cuisines, is also used in traditional medicine for the treatment of several pathological conditions; however, little is known about their bioactive compounds. Recent studies revealed the crucial role of the phenolic compounds namely flavonoids and tannins on the infusion bioactivity. Flavonoids have already been characterized; however the tannin fraction of lemongrass infusion is still uncharted. The aim of the present work is to characterize this fraction, and to evaluate its contribution to the antioxidant potential of this plant. Chemical characterization was achieved by HPLC-DAD-ESI/tandem MS and the antioxidant activity was evaluated using DPPH, ABTS and FRAP assays. Hetero-dimeric flavan structures have been described for the first time in lemongrass consisting of apigeniflavan or luteoliflavan units linked to a flavanone, either naringenin or eriodictyol, which may occur as aglycone or glycosylated forms. The antioxidant capacity of the fraction containing these compounds was significantly higher than the infusion, indicating its potential as a source of natural antioxidants.

  6. Cymbopogon citratus and Camellia sinensis extracts selectively induce apoptosis in cancer cells and reduce growth of lymphoma xenografts in vivo

    Science.gov (United States)

    Philion, Cory; Ma, Dennis; Ruvinov, Ivan; Mansour, Fadi; Pignanelli, Christopher; Noel, Megan; Saleem, Ammar; Arnason, John; Rodrigues, Mark; Singh, Inderpal; Ropat, Jesse; Pandey, Siyaram

    2017-01-01

    Cancer cells are reported to have elevated levels of reactive oxygen species (ROS) and are highly dependent on cellular defense mechanisms against oxidative stress. Numerous nutraceuticals and natural polyphenolic compounds have a wide range of abilities to alter cellular redox states with potential implications in various diseases. Furthermore, therapeutic options for cancers are mostly nonselective treatments including genotoxic or tubulin-targeting compounds. Some of the natural extracts, containing multiple bioactive compounds, could target multiple pathways in cancer cells to selectively induce cell death. Cymbopogon citratus (lemongrass) and Camellia sinensis (white tea) extracts have been shown to have medicinal properties, however, their activity against lymphoma and leukemia, as well as mechanistic details, have not been fully characterized. Herein, we report potent anti-cancer properties in dose and time-dependent manners of ethanolic lemongrass and hot water white tea extracts in lymphoma and leukemia models. Both extracts were able to effectively induce apoptosis selectively in these human cancer cell types. Interestingly, ethanolic lemongrass extract induces apoptosis primarily by the extrinsic pathway and was found to be dependent on the generation of ROS. Conversely, apoptotic induction by hot water white tea extract was independent of ROS. Furthermore, both of these extracts caused mitochondrial depolarization and decreased rates of oxygen consumption in lymphoma and leukemia cells, leading to cell death. Most importantly, both these extracts were effective in reducing tumor growth in human lymphoma xenograft models when administered orally. Thus, these natural extracts could have potential for being nontoxic alternatives for the treatment of cancer. PMID:29340014

  7. Activity of Ocimum basilicum, Ocimum canum, and Cymbopogon citratus essential oils against Plasmodium falciparum and mature-stage larvae of Anopheles funestus s.s.

    Directory of Open Access Journals (Sweden)

    Akono Ntonga Patrick

    2014-01-01

    Full Text Available The biological activities of essential oils from three plants grown in Cameroon: Ocimum basilicum, Ocimum canum, and Cymbopogon citratus were tested against Plasmodium falciparum and mature-stage larvae of Anopheles funestus. Gas chromatography and gas chromatography – mass spectrometry analyses showed that the main compounds are geranial, 1,8-cineole and linalool in C. citratus, O. canum and O. basilicum, respectively. Larvicidal tests carried out according to the protocol recommended by the World Health Organization showed that the essential oil of leaves of C. citratus is the most active against larvae of An. funestus (LC50 values = 35.5 ppm and 34.6 ppm, respectively, for larval stages III and IV after 6 h of exposure. Besides, the in vitro anti-plasmodial activity evaluated by the radioisotopic method showed that the C. citratus oil is the most active against P. falciparum, with an IC50 value of 4.2 ± 0.5 μg/mL compared with O. canum (20.6 ± 3.4 μg/mL and O. basilicum (21 ± 4.6 μg/mL. These essential oils can be recommended for the development of natural biocides for fighting the larvae of malaria vectors and for the isolation of natural products with anti-malarial activity.

  8. Chemical Composition of Essential Oils from Thymus vulgaris, Cymbopogon citratus, and Rosmarinus officinalis, and Their Effects on the HIV-1 Tat Protein Function.

    Science.gov (United States)

    Feriotto, Giordana; Marchetti, Nicola; Costa, Valentina; Beninati, Simone; Tagliati, Federico; Mischiati, Carlo

    2018-02-01

    New drugs would be beneficial to fight resistant HIV strains, in particular those capable of interfering with essential viral functions other than those targeted by highly active antiretroviral therapy drugs. Despite the central role played by Tat protein in HIV transcription, a search for vegetable extracts able to hamper this important viral function was never carried out. In this work, we evaluated the chemical composition and possible interference of essential oil from Thymus vulgaris, Cananga odorata, Cymbopogon citratus, and Rosmarinus officinalis with the Tat/TAR-RNA interaction and with Tat-induced HIV-1 LTR transcription. GC/MS Analysis demonstrated the biodiversity of herbal species translated into essential oils composed of different blends of terpenes. In all of them, 4 - 6 constituents represent from 81.63% to 95.19% of the total terpenes. Essential oils of Thymus vulgaris, Cymbopogon citratus, and Rosmarinus officinalis were active in interfering with Tat functions, encouraging further studies to identify single terpenes responsible for the antiviral activity. In view of the quite different composition of these essential oils, we concluded that their interference on Tat function depends on specific terpene or a characteristic blend. © 2018 Wiley-VHCA AG, Zurich, Switzerland.

  9. simulation effect of gamma radiation on growth and essential oil production of lemongrass cymbopogon citratus L

    International Nuclear Information System (INIS)

    Abo-Elseoud, M.A.; Deaf, M.N.; Afifi, R.A; Abo-Etia, A.M.

    2004-01-01

    field experiment was conducted to study the effect of different doses of gamma radiation on growth and volatile oil production of lemongrass, C ymbopogon citratus L. i n this consideration, lemongrass segments were exposed to irradiation doses of 0.5,10,20 and 40 gray and cultivated in the experimental field of atomic energy authority, Inshas. three consequent harvest were taken at flowering stage as the fresh weights were recorded . volatile oil contents, volatile oil constituents and sugars content were determined in the plants herb. results showed that irradiation doses up to 20 gray induced a stimulation effect on plant growth as it increased the fresh weight of plant herb. data of total oil content (cc/plant ) showed noticeable enhancement up to irradiation dose of 20 gray, however, a slight decline was recorded with the higher irradiation dose of 40 gray. GLC of lemongrass volatile oil revealed that 19 components are resulted as citral aa nd citral bw ere the most predominant components . the impact of the studied irradiation treatments on the constituents of lemongrass oil was discussed. in addition, sugars content were determined and some increases were resulted in response to the studied gamma irradiation treatments

  10. Extraction of citral oil from lemongrass (Cymbopogon Citratus) by steam-water distillation technique

    Science.gov (United States)

    Alam, P. N.; Husin, H.; Asnawi, T. M.; Adisalamun

    2018-04-01

    In Indonesia, production of citral oil from lemon grass (Cymbopogon Cytratus) is done by a traditional technique whereby a low yield results. To improve the yield, an appropriate extraction technology is required. In this research, a steam-water distillation technique was applied to extract the essential oil from the lemongrass. The effects of sample particle size and bed volume on yield and quality of citral oil produced were investigated. The drying and refining time of 2 hours were used as fixed variables. This research results that minimum citral oil yield of 0.53% was obtained on sample particle size of 3 cm and bed volume of 80%, whereas the maximum yield of 1.95% on sample particle size of 15 cm and bed volume of 40%. The lowest specific gravity of 0.80 and the highest specific gravity of 0.905 were obtained on sample particle size of 8 cm with bed volume of 80% and particle size of 12 cm with bed volume of 70%, respectively. The lowest refractive index of 1.480 and the highest refractive index of 1.495 were obtained on sample particle size of 8 cm with bed volume of 70% and sample particle size of 15 cm with bed volume of 40%, respectively. The solubility of the produced citral oil in alcohol was 70% in ratio of 1:1, and the citral oil concentration obtained was around 79%.

  11. Avaliação in vitro da ação do óleo essencial de capim limão (Cymbopogon citratus sobre o carrapato bovino Rhipicephalus (Boophilus microplus In vitro evaluation of the action of lemon grass (Cymbopogon citratus essential oil on the cattle tick Rhipicephalus (Boophilus microplus

    Directory of Open Access Journals (Sweden)

    F.C.C. Santos

    2012-01-01

    Full Text Available O uso indiscriminado de produtos químicos no controle do carrapato bovino constitui a principal causa do gradativo aumento do número de cepas resistentes deste parasita às bases disponíveis no mercado. A utilização de óleos essenciais e extratos vegetais é uma prática antiga no controle de carrapatos, porém só recentemente tem recebido a devida atenção dos pesquisadores. O objetivo deste experimento foi avaliar a eficácia in vitro do óleo de capim limão (Cymbopogon citratus sobre fêmeas ingurgitadas de Rhipicephalus (Boophilus microplus através do exame de biocarrapaticidograma. Foram testadas seis diluições do óleo de C. citratus (1; 5; 10; 25; 50 e 100% em uma população de carrapatos resistentes a amidínicos e piretróides sintéticos. A inibição de postura foi de 3; 23; 46; 66; 46 e 46%, a eclosão larval foi de 83; 58; 31; 0; 38 e 25% e a eficácia do tratamento foi de 32; 64; 83; 100; 88 e 82%, respectivamente. O óleo de C. citratus apresentou controle parcial do carrapato R. microplus in vitro, mesmo frente a populações resistentes a produtos químicos.The indiscriminate use of chemical products to control the cattle tick is the main cause of the gradual increase in the number of strains of this parasite that are resistant to the bases currently available in the market. The use of essential oils and plant extracts is an ancient practice for tick control; however, only recently has it received due attention by researchers. The aim of this experiment was to evaluate the in vitro efficacy of lemongrass (Cymbopogon citratus essential oil on engorged females of Rhipicephalus (Boophilus microplus through immersion test. Six concentrations of Cymbopogon citratus oil (1; 5; 10; 25; 50 and 100% were tested against a tick population resistant to synthetic formamidines and pyrethroids. The inhibition of egg-laying was 3; 23; 46; 66; 46 and 46%, the hatching was 83; 58; 31; 0; 38 and 25%, and the treatment efficacy was 32

  12. Conversion of Natural Aldehydes from Eucalyptus citriodora, Cymbopogon citratus, and Lippia multiflora into Oximes: GC-MS and FT-IR Analysis †

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    Igor W. Ouédraogo

    2009-08-01

    Full Text Available Three carbonyl-containing extracts of essential oils from Eucalyptus citriodora (Myrtaceae, Cymbopogon citratus (Gramineae and Lippia multiflora (Verbenaceae were used for the preparation of oximes. The reaction mixtures were analyzed by GC-MS and different compounds were identified on the basis of their retention times and mass spectra. We observed quantitative conversion of aldehydes to their corresponding oximes with a purity of 95 to 99%. E and Z stereoisomers of the oximes were obtained and separated by GC-MS. During GC analysis, the high temperature in the injector was shown to cause partial dehydratation of oximes and the resulting nitriles were readily identified. Based on FT-IR spectroscopy, that revealed the high stability and low volatility of these compounds, the so-obtained oximes could be useful for future biological studies.

  13. Use of gamma radiation cobalt 60 for disinfestation of Lasioderma serricorne (Fabricius, 1972) (Coleoptera: Anobiidae) in Cymbopogon citratus stapf and Ocimun basillicum L. dehydrated

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Amanda C.O.; Potenza, Marcos R.; Alves, Juliana N.; Justi Junior, Joao [Instituto Biologico, Sao Paulo, SP (Brazil). Centro de Pesquisa e Desenvolvimento de Sanidade Vegetal]. E-mail: potenza@biologico.sp.gov.br; Arthur, Valter [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil)]. E-mail: arthur@cena.usp.br

    2007-07-01

    Stored products such as grains, flours, dry fruits and spices are normally infested by pests as beetles (Lasioderma serricorne), mites and moths, depreciating the product visually and promoting its deterioration. To improve the quality of spices, medicinal plants, seasoning and others foodstuffs there is a need for adequate methods of handling, correct identification of the species, adequate collection, pre and post-treatment procedures and adequate storage. The objective of this work was to determine the dose of gamma radiation for the disinfestations of medicinal and aromatic plants dehydrated infested by L. serricone. The plants used in this study were Cymbopogon citratus stapf (lemon grass) and Ocimun basillicum L. (basil) in this dehydrated form. The experiment was carried out in the Arthropods Laboratory of the Instituto Biologico/SP, during the months of January and May 2006, and the irradiations were carried out in the Instituto de Pesquisas Energeticas e Nucleares-IPEN/CNEN/SP, using an experimental Cobalt 60 irradiator, model Gammacell 220. Each treatment consisted of 5 parcels containing 10g of dehydrated products infested with 20 last instar larvae of L. serricorne, conditioned in plastic 10x10 cm containers with small punctures in the cover to allow internal aeration. The substratum previously infested was kept for 1 day in a acclimatized room at 27 {+-} 2 deg C, after this period the substratum was submitted to increasing doses of gamma radiation: 0; 0,5; 0,75; 1,0; 1,25; 1,50; 1,75; 2,0; 2,25; 2,50 e 2,75 kGy. After irradiation, the samples were kept in a acclimatized room at 27 {+-} 2 deg C of temperature and relative humidity of 70 {+-} 5 % and after a 45 days period the number of adults insects emerged was evaluated. The lethal dose of gamma radiation for L. serrricorne last instar larvae on Cymbopogon citratus stapf and Ocimun basillicum L. was 1,75 kGy. (author)

  14. Cymbopogon citratus and NaNO2 Behaviours in 3.5% NaCl-Immersed Steel-Reinforced Concrete: Implications for Eco-Friendly Corrosion Inhibitor Applications for Steel in Concrete

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    Joshua Olusegun Okeniyi

    2018-01-01

    Full Text Available This paper studies behaviours of Cymbopogon citratus leaf-extract and NaNO2, used as equal-mass admixture models, in 3.5% NaCl-immersed steel-reinforced concrete by nondestructive electrochemical methods and by compressive-strength improvement/reduction effects. Corrosion-rate, corrosion-current, and corrosion-potential constitute electrochemical test-techniques while compressive-strength effect investigations followed ASTM C29 and ASTM C33, in experiments using positive-controls for the electrochemical and compressive-strength studies. Analyses of the different electrochemical test-results mostly portrayed agreements on reinforcing-steel anticorrosion effects by the concentrations of natural plant and of chemical admixtures in the saline/marine simulating-environment and in the distilled H2O (electrochemical positive control of steel-reinforced concrete immersions. These indicated that little amount (0.0833% cement for concrete-mixing of Cymbopogon citratus leaf-extract was required for optimal inhibition efficiency, η = 99.35%, on reinforcing-steel corrosion, in the study. Results of compressive-strength change factor also indicated that the 0.0833% Cymbopogon citratus concentration outperformed NaNO2 admixture concentrations also in compressive-strength improvement effects on the NaCl-immersed steel-reinforced concrete. These established implications, from the study, on the suitability of the eco-friendly Cymbopogon citratus leaf-extract for replacing the also highly effective NaNO2 inhibitor of steel-in-concrete corrosion in concrete designed for the saline/marine service-environment.

  15. Combined Effect of Gamma Radiation and Cymbopogon Citratus L. Essential Oil on the Growth and Morphogenesis of Penicillium Digitatum Sacc. The Causal Agent of Green Mold of Citrus Fruits

    International Nuclear Information System (INIS)

    SalemM, E.A.

    2011-01-01

    The growth of Penicillium digitatum Sacc. was completely inhibited by using 2.5 l/ml or 3 l/ml of Cymbopogon citratus essential oil applied by fumigation or contact method on Czapek's medium, respectively. Two kGy gamma radiation treatment decreased the severity of infection of green rot caused by P. digitatum from 100% to 9.8% after 2 weeks of storage. Also, pre-treatment of orange fruits by 2.5 l/ml C. citratus before 2 kGy irradiation prevented infection by green rot for 21 days and decreased the severity of infection to 9.5% for 28 days of storage at 20 C. The microscopic observation using scanning electron microscope (SEM) was carried out to study the ultra structure modifications of P. digitatum after treatment. The mycelium of the fungus fumigated with the sub-lethal dose of C. citratus showed large alteration and distortion in hyphal and spores morphology.

  16. Use of gamma radiation cobalt 60 for disinfestation of Lasioderma serricorne (Fabricius, 1972) (Coleoptera: Anobiidae) in Cymbopogon citratus stapf and Ocimun basillicum L. dehydrated

    International Nuclear Information System (INIS)

    Ramos, Amanda C.O.; Potenza, Marcos R.; Alves, Juliana N.; Justi Junior, Joao

    2007-01-01

    Stored products such as grains, flours, dry fruits and spices are normally infested by pests as beetles (Lasioderma serricorne), mites and moths, depreciating the product visually and promoting its deterioration. To improve the quality of spices, medicinal plants, seasoning and others foodstuffs there is a need for adequate methods of handling, correct identification of the species, adequate collection, pre and post-treatment procedures and adequate storage. The objective of this work was to determine the dose of gamma radiation for the disinfestations of medicinal and aromatic plants dehydrated infested by L. serricone. The plants used in this study were Cymbopogon citratus stapf (lemon grass) and Ocimun basillicum L. (basil) in this dehydrated form. The experiment was carried out in the Arthropods Laboratory of the Instituto Biologico/SP, during the months of January and May 2006, and the irradiations were carried out in the Instituto de Pesquisas Energeticas e Nucleares-IPEN/CNEN/SP, using an experimental Cobalt 60 irradiator, model Gammacell 220. Each treatment consisted of 5 parcels containing 10g of dehydrated products infested with 20 last instar larvae of L. serricorne, conditioned in plastic 10x10 cm containers with small punctures in the cover to allow internal aeration. The substratum previously infested was kept for 1 day in a acclimatized room at 27 ± 2 deg C, after this period the substratum was submitted to increasing doses of gamma radiation: 0; 0,5; 0,75; 1,0; 1,25; 1,50; 1,75; 2,0; 2,25; 2,50 e 2,75 kGy. After irradiation, the samples were kept in a acclimatized room at 27 ± 2 deg C of temperature and relative humidity of 70 ± 5 % and after a 45 days period the number of adults insects emerged was evaluated. The lethal dose of gamma radiation for L. serrricorne last instar larvae on Cymbopogon citratus stapf and Ocimun basillicum L. was 1,75 kGy. (author)

  17. In vitro antimicrobial properties of plant essential oils thymus vulgaris, cymbopogon citratus and laurus nobilis against five important foodborne pathogens Propriedades antibacterianas in vitro de óleos essenciais de thymus vulgaris, cymbopogon citratus e laurus nobilis contra cinco importantes bactérias patogênicas veiculadas por alimentos

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    Alessandra Farias Millezi

    2012-03-01

    Full Text Available Several essential oils of condiment and medicinal plants possess proven antimicrobial activity and are of important interest for the food industry. Therefore, the Minimum Inhibitory Concentrations (MIC of those oils should be determined for various bacteria. MIC varies according to the oil used, the major compounds, and the physiology of the bacterium under study. In the present study, the essential oils of the plants Thymus vulgaris (time, Cymbopogon citratus (lemongrass and Laurus nobilis (bay were chemically quantified, and the MIC was determined on the bacteria Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Listeria monocytogenes ATCC 19117, Salmonella enterica Enteritidis S64, and Pseudomonas aeruginosa ATCC 27853. The essential oil of C. citratus demonstrated bacterial activity at all concentrations tested and against all of the bacteria tested. The majority of essential oil compounds were geranial and neral. The major constituent of T. vulgaris was 1.8-cineol and of L. nobilis was linalool, which presented lower antibacterial activity, followed by 1.8-cineol. The Gram-negative bacteria demonstrated higher resistance to the use of the essential oils tested in this study. E. coli was the least sensitive and was inhibited only by the oils of C. citratus and L. nobilis.Diversos óleos essenciais de plantas condimentares e medicinais possuem atividade antimicrobiana comprovada, sendo de grande interesse para a indústria de alimentos. Dessa forma, as Concentrações Mínimas Inibitórias (CMI desses óleos para diversas bactérias devem ser determinadas. As CMI variam de acordo com o óleo utilizado, dos compostos majoritários e da fisiologia da bactéria em estudo. Na presente pesquisa, os óleos essenciais das plantas Thymus vulgaris (tomilho, Cymbopogon citratus (capim-limão e Laurus nobilis (louro foram quantificados quimicamente e determinou-se a CMI sobre as bactérias Staphylococcus aureus ATCC 25923, Escherichia. coli

  18. Angolan Cymbopogon citratus used for therapeutic benefits: nutritional composition and influence of solvents in phytochemicals content and antioxidant activity of leaf extracts.

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    Soares, Marta O; Alves, Rita C; Pires, Pedro C; Oliveira, M Beatriz P P; Vinha, Ana F

    2013-10-01

    Folk medicine is a relevant and effective part of indigenous healthcare systems which are, in practice, totally dependent on traditional healers. An outstanding coincidence between indigenous medicinal plant uses and scientifically proved pharmacological properties of several phytochemicals has been observed along the years. This work focused on the leaves of a medicinal plant traditionally used for therapeutic benefits (Angolan Cymbopogon citratus), in order to evaluate their nutritional value. The bioactive phytochemical composition and antioxidant activity of leaf extracts prepared with different solvents (water, methanol and ethanol) were also evaluated. The plant leaves contained ∼60% of carbohydrates, protein (∼20%), fat (∼5%), ash (∼4%) and moisture (∼9%). The phytochemicals screening revealed the presence of tannins, flavonoids, and terpenoids in all extracts. Methanolic extracts also contained alkaloids and steroids. Several methods were used to evaluate total antioxidant capacity of the different extracts (DPPH·, NO·, and H₂O₂ scavenging assays, reducing power, and FRAP). Ethanolic extracts presented a significantly higher antioxidant activity (p<0.05) except for FRAP, in which the best results were achieved by the aqueous extracts. Methanolic extracts showed the lowest radical scavenging activities for both DPPH· and NO· radicals. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Effect of Cymbopogon citratus (lemongrass) and Syzygium aromaticum (clove) oils on the morphology and mortality of Aedes aegypti and Anopheles dirus larvae.

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    Soonwera, Mayura; Phasomkusolsil, Siriporn

    2016-04-01

    Cymbopogon citratus (lemongrass) and Syzygium aromaticum (clove) oils were evaluated to determine mortality rates, morphological aberrations, and persistence when used against third and fourth larval instars of Aedes aegypti and Anopheles dirus. The oils were evaluated at 1, 5, and 10 % concentrations in mixtures with soybean oil. Persistence of higher concentrations was measured over a period of 10 days. For Ae. aegypti, both plant oils caused various morphological aberrations to include deformed larvae, incomplete eclosion, white pupae, deformed pupae, dead normal pupae, and incomplete pupal eclosion. All of these aberrations led to larval mortality. In Ae. aegypti larvae, there were no significant differences in mortality at days 1, 5, and 10 or between third and fourth larval instar exposure. In An. dirus, morphological aberrations were rare and S. aromaticum oil was more effective in causing mortality among all larval stages. Both oils were equally effective at producing mortality on days 1, 5, and 10. Both oils had slightly increased LT50 rates from day 1 to day 10. In conclusion, both lemongrass and clove oils have significant effects on the immature stages of Ae. aegypti and An. dirus and could potentially be developed for use as larvicides.

  20. Cholesterol reduction and lack of genotoxic or toxic effects in mice after repeated 21-day oral intake of lemongrass (Cymbopogon citratus) essential oil.

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    Costa, Celso A R A; Bidinotto, Lucas T; Takahira, Regina K; Salvadori, Daisy M F; Barbisan, Luís F; Costa, Mirtes

    2011-09-01

    Cymbopogon citratus (lemongrass) is currently used in traditional folk medicine. Although this species presents widespread use, there are no scientific data on its efficacy or safety after repeated treatments. Therefore, this work investigated the toxicity and genotoxicity of this lemongrass's essential oil (EO) in male Swiss mice. The single LD(50) based on a 24h acute oral toxicity study was found to be around 3500 mg/kg. In a repeated-dose 21-day oral toxicity study, mice were randomly assigned to two control groups, saline- or Tween 80 0.01%-treated groups, or one of the three experimental groups receiving lemongrass EO (1, 10 or 100mg/kg). No significant changes in gross pathology, body weight, absolute or relative organ weights, histology (brain, heart, kidneys, liver, lungs, stomach, spleen and urinary bladder), urinalysis or clinical biochemistry were observed in EO-treated mice relative to the control groups. Additionally, blood cholesterol was reduced after EO-treatment at the highest dose tested. Similarly, data from the comet assay in peripheral blood cells showed no genotoxic effect from the EO. In conclusion, our findings verified the safety of lemongrass intake at the doses used in folk medicine and indicated the beneficial effect of reducing the blood cholesterol level. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Potential antioxidant and cytoprotective effects of essential oil extracted from Cymbopogon citratus on OxLDL and H2O2 LDL induced Human Peripheral Blood Mononuclear Cells (PBMC

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    Jamuna S.

    2017-06-01

    Full Text Available Cymbopogon citratus (lemon grass is commonly used in traditional folk medicine. The essential oil extracted from C. citratus has been reported as a potential anti-oxidant and anti-inflammatory agent. This study has been designed to explore the protective effect of C. citratus (lemon grass against modified LDL (OxLDL and H2O2 LDL induced cytotoxicity in Peripheral Blood Mononuclear Cells (PBMC. The essential oil extracted from C. citratus (EOC was subjected to FT-IR spectroscopic analysis for the identification of functional groups. In vitro antioxidant assays were carried out to assess the electron donating capability of EOC as compared with a known standard L-ascorbic acid. The cytoprotective effects of EOC were determined in PBMC induced with modified LDL. Spectra obtained from FT-IR analysis showed the presence of functional groups in EOC such as H-bonded, OH stretching, NH stretching, aldehydeCH stretching, aldehyde/ketoneCO stretching, CC-stretching, CH3 bending, CH in plane bending. EOC has greater antioxidant property when compared with the standard L-ascorbic acid. EOC at all test concentrations demonstrated free radical scavenging activity and cytoprotective effect when challenged against modified LDL in PBMC. The above results show EOC as a promising antioxidant and cytoprotective agent.

  2. Liquid and vapour-phase antifungal activities of selected essential oils against candida albicans: microscopic observations and chemical characterization of cymbopogon citratus

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    Malik Anushree

    2010-11-01

    Full Text Available Abstract Background Use of essential oils for controlling Candida albicans growth has gained significance due to the resistance acquired by pathogens towards a number of widely-used drugs. The aim of this study was to test the antifungal activity of selected essential oils against Candida albicans in liquid and vapour phase and to determine the chemical composition and mechanism of action of most potent essential oil. Methods Minimum Inhibitory concentration (MIC of different essential oils in liquid phase, assayed through agar plate dilution, broth dilution & 96-well micro plate dilution method and vapour phase activity evaluated through disc volatilization method. Reduction of C. albicans cells with vapour exposure was estimated by kill time assay. Morphological alteration in treated/untreated C. albicans cells was observed by the Scanning electron microscopy (SEM/Atomic force microscopy (AFM and chemical analysis of the strongest antifungal agent/essential oil has been done by GC, GC-MS. Results Lemon grass (Cymbopogon citratus essential oil exhibited the strongest antifungal effect followed by mentha (Mentha piperita and eucalyptus (Eucalyptus globulus essential oil. The MIC of lemon grass essential oil in liquid phase (288 mg/l was significantly higher than that in the vapour phase (32.7 mg/l and a 4 h exposure was sufficient to cause 100% loss in viability of C. albicans cells. SEM/AFM of C. albicans cells treated with lemon grass essential oil at MIC level in liquid and vapour phase showed prominent shrinkage and partial degradation, respectively, confirming higher efficacy of vapour phase. GC-MS analysis revealed that lemon grass essential oil was dominated by oxygenated monoterpenes (78.2%; α-citral or geranial (36.2% and β-citral or neral (26.5%, monoterpene hydrocarbons (7.9% and sesquiterpene hydrocarbons (3.8%. Conclusion Lemon grass essential oil is highly effective in vapour phase against C. albicans, leading to deleterious

  3. Isolasi Minyak Atsiri dari Sereh Merah (Andropogon citratus DC.) Segar dan Kering Serta Analisis Komponen Secara GC-MS

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    Situmorang, Betty Meilya

    2013-01-01

    Essential oil is a term used for volatile oil and obtained from part of plant such as leaves, flowers, fruit, bark and roots. Lemongrass oil is a major export commodities among the various types of essential oil. The main content of lemongrass oil are sitronellal and geraniol, and content oil of lemongrass is 0.5 to 1.2%. Andropogon citratus DC. of the family Poaceae is one of plant that contains essential oil and is widely used as a liniment. The objective of this research is to determine th...

  4. Avaliação da composição química de Cymbopogon citratus Stapf cultivado em ambientes com diferentes níveis de poluição e a influência na composição do chá = Evaluation of the chemical composition of Cymbopogon citratus Stapf growing in environments with different pollution levels and the influence on tea composition

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    Maria Almerice Lopes da Silva

    2010-01-01

    Full Text Available Cymbopogon citratus Stapf, o popular capim-santo, é espécie originária da Índia, que chegou ao Brasil, possivelmente, no tempo colonial, e era utilizada como planta ornamental, sendo encontrada cultivada em todo o país. Diversos são os usos populares para essa planta, desde tratamento de dores estomacais, intestinais, antidiarreico, até anticelulite e estética de cabelos oleosos. Essa planta se desenvolve em ambientes insalubres como beira de estrada, e isso pode levar a mudanças no seu aspecto químico e, em consequência disso, mudanças em seus derivados. Este trabalho analisou se ocorreu variação da composição química da planta cultivada na presença ou ausência de estresse ambiental (poluição urbana. Foram pesquisados por meio de cromatografia de camada delgada os seguintes compostos: saponinas, iridoides e proantocianidinas, mono e sesquiterpenos, triterpenos e esteroides, luteolina, polifenóis e alcaloides. Concluiu-se que este fator pode ter contribuído para modificação da composição química de suas folhas, reduzindo a síntese de compostos mais polares e favorecendo a síntese de possíveis leucoantocianidinas para provável proteção. Isso poderá acarretar ao chá alterações em sua propriedade farmacológica e toxicológica.Cymbopogon citratus Stapf, popularly known as lemongrass, is an Indian species. It possibly arrived in Brazil during colonial times, where it was used as an ornamental plant, and is found growing throughout the country. There are several popular uses for this plant, including as treatment for stomach pains, diarrhea and cellulite. This plant grows in polluted and unpolluted environments such as roadsides, which can lead to changes in its chemical aspects, and consequently changes in its manufacturing products. This study examined whether there were changes in the chemical composition of plants grown in the presence or absence of environmental stress (urban pollution. The following

  5. Plantes aromatiques du Plateau des Cataractes (Bassin du Congo. Caractérisation du chémotype de l'huile essentielle de Cymbopogon nardus (L. Rendle acclimaté au Congo-Brazzaville

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    Silou, T.

    2017-01-01

    Full Text Available Aromatic plants from the Plateau des Cataractes (Congo Basin. Chemotype characterization of essential oil of Cymbopogon nardus (L. Rendle acclimatized in Congo-Brazzaville. Description. The essential oils of Cymbopogon nardus (L. Rendle, Cymbopogon winterianus Jowitt, Cymbopogon flexuosus (Nees ex Steud. Wats and Cymbopogon citratus L. (DC. Stapf (lemongrass consist of more than 80% of the following constituents: citronellal, geraniol, citral, citronellol, geranyl acetate, and limonene. For the purposes of business transactions, it is therefore important to know the exact chemical composition of the essential oils produced. Objectives. Chemotype evaluation of C. nardus acclimatized on the Plateau des Cataractes. Method. The essential oils of C. nardus were extracted by hydrodistillation and analyzed by chromatography (GC and GC/MS over a period of more than ten years. Results. Cymbopogon nardus was found to produce a Java type citronella essential oil (C. winterianus with the following profile: citronellal (40-48%, geraniol (10-22%, citronellol (10-12%, limonene (2-3%, geranyl acetate (1-2%, linalool (1%. The difference between these two types of citronella, Java and Ceylon, was based on the relative proportions of their three main constituents: citronellal, geraniol and citronellol. Cymbopogon nardus is known for its high variability, with two varieties and sept subvarieties. Conclusions. The citronella established in West and Central Africa under the name of Cymbopogon nardus (Java type could be considered a Cymbopogon winterianus Jowitt, based on the chemical composition of its essential oil.

  6. Rendimento, composição química e atividade antilisterial de óleos essenciais de espécies de Cymbopogon Yield, chemical composition and antilisterial activity of essential oils from Cymbopogon species

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    M.M.M Oliveira

    2011-01-01

    Full Text Available Objetivou-se determinar o rendimento, a composição química e avaliar a atividade antilisterial dos óleos essenciais de Cymbopogon citratus (DC. Stapf. (capim-limão e Cymbopogon nardus (L. Rendle (capim-citronela, puros e em combinação. A obtenção dos óleos essenciais foi realizada a partir de folhas frescas, empregando-se a técnica de hidrodestilação e utilizando-se aparelho de Clevenger modificado. Os rendimentos foram calculados a partir da massa obtida na extração e da umidade do material vegetal. A análise qualitativa foi realizada por cromatografia em fase gasosa acoplada à espectrometria de massas e a avaliação dos teores dos constituintes químicos por cromatografia em fase gasosa com detector de ionização de chamas. O efeito bacteriostático de diferentes concentrações dos óleos essenciais, puros e em combinação, foi determinado pela técnica de difusão em ágar. As concentrações mínimas inibitórias (CMIs foram utilizadas na determinação do tempo de ação bactericida. O rendimento, em base seca, foi de 1,39% (v/p para o óleo essencial de C. citratus e de 2,27% (v/p para o óleo essencial de C. nardus. Geranial e neral foram os constituintes majoritários do óleo essencial de C. citratus, enquanto, para C. nardus, foram citronelal, geraniol e citronelol. A maioria das concentrações utilizadas mostrou-se efetiva contra Listeria monocytogenes e observaram-se efeitos bactericidas nas CMIs. Óleos essenciais de C. citratus e C. nardus, puros e em combinação, constituem novas alternativas de antibacterianos naturais a serem utilizados no controle de L. monocytogenes na indústria de alimentos.The aim of this study was to determine the yield and the chemical composition of essential oils from Cymbopogon citratus (DC. Stapf. (lemongrass and Cymbopogon nardus (L. Rendle (citronella, and to evaluate their antilisterial activity when pure and combined. The essential oils were obtained from fresh leaves

  7. Anti-proliferative effect of the essential oil of Cymbopogon citratus (DC) Stapf (lemongrass) on intracellular amastigotes, bloodstream trypomastigotes and culture epimastigotes of Trypanosoma cruzi (Protozoa: Kinetoplastida).

    Science.gov (United States)

    Santoro, G F; Cardoso, M G; Guimarães, L G L; Freire, J M; Soares, M J

    2007-10-01

    This study analyses the anti-proliferative effect of lemongrass essential oil and its main constituent (citral) on all 3 evolutive forms of Trypanosoma cruzi. Steam distillation was used to obtain lemongrass essential oil, with chemical composition determined by gas chromatography (GC) and GC coupled to mass spectrometry (GC-MS). The IC50/24 h (concentration that reduced the parasite population by 50%) of the oil and of citral upon T. cruzi was determined by cell counting in a Neubauer chamber, while morphological alterations were visualized by scanning and transmission electron microscopy. Treatment with the essential oil resulted in epimastigote growth inhibition with IC50=126.5 microg/ml, while the IC50 for trypomastigote lysis was 15.5 microg/ml. The IC50/48 h for the Association Index (% macrophage infection x number of amastigotes per cell) was 5.1 microg/ml, with a strong inhibition of intracellular amastigote proliferation. Ultrastructural analysis demonstrated cytoplasmic and nuclear extraction, while the plasma membrane remained morphologically preserved. Our data show that lemongrass essential oil is effective against T. cruzi trypomastigotes and amastigotes, and that its main component, citral, is responsible for the trypanocidal activity. These results indicate that essential oils can be promising anti-parasitic agents, opening perspectives to the discovery of more effective drugs of vegetal origin for treatment of parasitic diseases. However, additional cytotoxicity experiments on different cell lines and tests in a T. cruzi-mouse model are needed to support these data.

  8. Phytoremediation of metals using lemongrass (Cymbopogon citratus (D.C.) Stapf.) grown under different levels of red mud in soil amended with biowastes.

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    Gautam, Meenu; Pandey, Divya; Agrawal, Madhoolika

    2017-06-03

    Due to hostile condition of red mud (RM), its utilization for vegetation is restricted. Therefore, RM with biowastes as soil amendment may offer suitable combination to support plant growth with reduced risk of metal toxicity. To evaluate the effects of RM on soil properties, plant growth performance, and metal accumulation in lemongrass, a study was conducted using different RM concentrations (0, 5, 10, and 15% w/w) in soil amended with biowastes [cow dung manure (CD) or sewage-sludge (SS)]. Application of RM in soil with biowastes improved organic matter and nutrient contents and caused reduction in phytoavailable metal contents. Total plant biomass was increased under all treatments, maximally at 5% RM in soil with SS (91.4%) and CD (51.7%) compared to that in control (no RM and biowastes). Lemongrass acted as a potential metal-tolerant plant as its metal tolerance index is >100%. Based on translocation and bioconcentration factors, lemongrass acted as a potential phytostabilizer of Fe, Mn, and Cu in roots and was found efficient in translocation of Al, Zn, Cd, Pb, Cr, As, and Ni from roots to shoot. The study suggests that 5% RM with biowastes preferably SS may be used to enhance phytoremediation potential of lemongrass.

  9. Fungicidal and anti-aflatoxigenic effects of the essential oil of Cymbopogon citratus (DC.) Stapf. (lemongrass) against Aspergillus flavus Link. isolated from stored rice.

    Science.gov (United States)

    Paranagama, P A; Abeysekera, K H T; Abeywickrama, K; Nugaliyadde, L

    2003-01-01

    To develop a natural fungicide against aflatoxigenic fungi, to protect stored rice, using the essential oil of lemongrass. Aspergillus flavus Link. was isolated from stored rice and identified as an aflatoxigenic strain. Lemongrass oil was tested against A. flavus and the test oil was fungistatic and fungicidal against the test pathogen at 0.6 and 1.0 mg ml(-1), respectively. Aflatoxin production was completely inhibited at 0.1 mg ml(-1). The results obtained from the thin layer chromatographic bioassay and gas chromatography indicated citral a and b as the fungicidal constituents in lemongrass oil. During the fumigant toxicity assay of lemongrass oil, the sporulation and the mycelial growth of the test pathogen were inhibited at the concentrations of 2.80 and 3.46 mg ml(-1), respectively. Lemongrass oil could be used to manage aflatoxin formation and fungal growth of A. flavus in stored rice. Currently, fungicides are not used to control fungal pests or mycotoxin production on stored rice. Rice treated with the essential oil of lemongrass could be used to manage fungal pests as well as the insect pests in stored rice. The essential oil is chemically safe and acceptable to consumers, as synthetic chemical fungicides can cause adverse health effects to consumers.

  10. Cymbopogon Species; Ethnopharmacology, Phytochemistry and the Pharmacological Importance

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    Opeyemi Avoseh

    2015-04-01

    Full Text Available Cymbopogon genus is a member of the family of Gramineae which are herbs known worldwide for their high essential oil content. They are widely distributed across all continents where they are used for various purposes. The commercial and medicinal uses of the various species of Cymbopogon are well documented. Ethnopharmacology evidence shows that they possess a wide array of properties that justifies their use for pest control, in cosmetics and as anti-inflammation agents. These plants may also hold promise as potent anti-tumor and chemopreventive drugs. The chemo-types from this genus have been used as biomarkers for their identification and classification. Pharmacological applications of Cymbopogon citratus are well exploited, though studies show that other species may also useful pharmaceutically. Hence this literature review intends to discuss these species and explore their potential economic importance.

  11. ANÁLISE DA COMPOSIÇÃO QUÍMICA DO ÓLEO ESSENCIAL DE CAPIM SANTO (Cymbopogon citratus OBTIDO ATRAVÉS DE EXTRATOR POR ARRASTE COM VAPOR D´ÁGUA CONSTRUÍDO COM MATERIAS DE FÁCIL AQUISIÇÃO E BAIXO CUSTO

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    Felipe Maia Silva

    2014-08-01

    Full Text Available Os óleos essenciais são substâncias naturais de grande importância econômica, sendo utilizados em perfumaria, cosméticos, alimentos e medicamentos. São obtidos por diferentes métodos de extração e encontrados em diferentes partes de plantas aromáticas. Contudo, a aquisição de equipamentos para extração de óleos essenciais representa um custo significativo para as instituições de ensino e pesquisa do país, principalmente nos últimos anos em que tem ocorrido redução de investimentos nas áreas de Ciência e Tecnologia. Desta forma, esse trabalho teve como objetivo a construção de um extrator de óleo essencial utilizando materiais de fácil acesso e mão de obra local. O extrator construído possui as dimensões de 60 cm de altura e 30 cm de diâmetro. Seu aquecimento é realizado por resistência elétrica com temperatura controlada por termostato (faixa de 0 a 120°C e possui uma campânula metálica vedada por selo d’água que está acoplada a um sistema de condensação. O experimento teste foi realizado fazendo extração de 612 g de capim santo (Cymbopogon citratus. Após análise obteve-se um rendimento de 0,48% de óleo essencial na extração. Portanto, este trabalho demonstra a busca no desenvolvimento de tecnologias inovadoras, fazendo uso de materiais facilmente encontrados no mercado e utilizando mão de obra local, contribuindo, não só para o acúmulo de conhecimento acadêmico, mas, acima de tudo, com a capacitação de recursos humanos, geração de renda local e com a transferência de novas tecnologias que possam servir de base para a elaboração de novos produtos, neste caso, os óleos essenciais.

  12. Influência da luz e da temperatura sobre a oxidação do óleo essencial de capim-limão (Cymbopogon citratus (D.C.) Stapf) Influence of light and temperature on the oxidation of the essential oil of lemongrass (Cymbopogon Citratus (D.C.) Stapf)

    OpenAIRE

    Luiz Gustavo de L. Guimarães; Maria das Graças Cardoso; Lidiany M. Zacaroni; Rafaela K. de Lima; Flávio A. Pimentel; Augusto R. de Morais

    2008-01-01

    The identification of the chemical compounds of the essential oil was performed with a gas chromatograph coupled to a mass spectrometer. The oil was left in the presence and absence of light and submitted to different temperatures to evaluate its stability. The yields of the major compounds were evaluated every fifteen days. Citral and myrcene, the major compounds of the essential oil, were degraded over time in both the presence and absence of light, but temperature only influenced the degra...

  13. Influência da luz e da temperatura sobre a oxidação do óleo essencial de capim-limão (Cymbopogon citratus (D.C. Stapf Influence of light and temperature on the oxidation of the essential oil of lemongrass (Cymbopogon Citratus (D.C. Stapf

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    Luiz Gustavo de L. Guimarães

    2008-01-01

    Full Text Available The identification of the chemical compounds of the essential oil was performed with a gas chromatograph coupled to a mass spectrometer. The oil was left in the presence and absence of light and submitted to different temperatures to evaluate its stability. The yields of the major compounds were evaluated every fifteen days. Citral and myrcene, the major compounds of the essential oil, were degraded over time in both the presence and absence of light, but temperature only influenced the degradation of myrcene.

  14. Bioatividade de extratos hidroalcoólicos de Cymbopogon citratus (DC. Stapf. sobre picão-preto (Bidens pilosa L. e alface (Lactuca sativa L. Bioactivity of hydroalcoholic extracts of Cymbopogon citratus (DC. Stapf. on germination and early growth of beggartick (Bidens pilosa L. and lettuce (Lactuca sativa L.

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    L.L. Lousada

    2012-01-01

    Full Text Available Este trabalho visou avaliar a bioatividade de extratos hidroalcoólicos de capim-limão sobre germinação e crescimento inicial da planta daninha picão-preto (Bidens pilosa L. e da planta teste alface (Lactuca sativa L.. A partir de maceração hidroalcoólica de folhas secas e rasuradas (127,46 g de capim-limão em 1L de álcool de cereais (70%, foram preparados os tratamentos como extratos hidroalcoólicos (HA pela diluição (v/v do macerado filtrado em água deionizada na proporção 1:1 (HA1:1 e 1:2 (HA1:2; dos quais foram obtidos os respectivos extratos secos (ES, a partir da evaporação da fase líquida de duas alíquotas de 50 mL de cada extrato HA, que após re-suspendidas em igual volume de água, sendo uma autoclavada (1 atm por 15 minutos, resultando nos extratos secos de HA1:1 e HA1:2 autoclavados (ES1:1A e ES1:2A e nos extratos secos não autoclavados (ES1:1 e ES1:2; e água (AG como controle. No primeiro dia dos bioensaios, foram aplicados 2 mL dos tratamentos, em DIC, com cinco repetições. Avaliou-se a porcentagem de germinação (G%, Índice de Velocidade de Germinação (IVG, altura da parte aérea (AA e comprimento de radícula (CR de aquênios (25 de picão-preto e de alface distribuídos em placas de Petri e mantidos em câmara de germinação (B.O.D. por duas semanas. Os extratos HA1:1 e HA1:2 inibiram a G%, AA e CR das duas espécies. Todos os extratos secos reduziram a G%, IVG e o CR da alface. Para o picão preto, apenas o extrato ES1:1 reduziu a G% e o IVG foi reduzido por todos os extratos, a exceção do ES1:1A, mas nenhum extrato influenciou o crescimento inicial desta espécie.This study aimed to evaluate the bioactivity of hydroalcoholic extract of lemongrass on the germination and early growth of the weed plant beggartick (Bidens pilosa L. and the test plant lettuce (Lactuca sativa L.. From the hydroalcoholic maceration of dried and cut leaves of lemon grass (127.46 g in 1 L grain alcohol (70%, the following treatments were prepared, hydro-alcoholic (HA extracts by diluting (v/v the macerate in deionized water at 1:1 (HA1:1 and 1:2 (HA1:2 proportions, obtaining the respective dried extracts (DE from the evaporation of the liquid phase of two 50-mL aliquots of each HA extract; after resuspension in the same water volume, one aliquot was autoclaved (1 atm for 15 minutes resulting in HA1:1 and HA1:2 dried autoclaved extracts (DE1:1A and DE1:2A and in dried non-autoclaved extracts (ES1:1 and ES1:2, and water as control. On the first day of bioassays, 2mL of treatments were applied, in completely randomized design, with 5 replicates. Germination percentage (G%, Germination Speed Index (GSI, shoot height (SH and radicle length (RL of achenes (25 of beggartick and lettuce were evaluated after having been distributed in Petri dishes and kept in a germination chamber (B.O.D. for two weeks. HA1:1 and HA1:2 extracts inhibited G%, SH and RL of both species. All dried extracts reduced G%, GSI and CR of lettuce. For beggartick, only ES1:1 extract reduced G% while GSI was reduced in all extracts, except ES1:1A, but no extract influenced the early growth of this species.

  15. Qualidade de produtos a base de plantas medicinais comercializados no Brasil: castanha-da-índia (Aesculus hippocastanum L., capim-limão (Cymbopogon citratus (DC. Stapf e centela (Centella asiatica (L. Urban Quality of products made from medicinal plants commercialized in Brazil: horsechestnut (Aesculus hippocastanum L., lemongrass (Cymbopogon citratus (DC. Stapf, and gotu kola (Centella asiatica (L. Urban

    Directory of Open Access Journals (Sweden)

    Joabe Gomes de Melo

    2007-03-01

    Full Text Available Com o objetivo de avaliar a qualidade de produtos a base de plantas medicinais, analisou-se dez amostras de castanha-da-índia, onze de capim-limão e seis de centela, comercializadas em farmácias da cidade do Recife, provenientes de indústrias de várias partes do país. Analisamos as informações técnico-científicas nos rótulos e/ou bulas de acordo com as exigências e obrigatoriedades da legislação brasileira (RDC n. 140 de 29/05/2003 e na RDC n. 102 de 30/11/2000, e embasamento da literatura científica. Também avaliou-se as características organolépticas, a autenticidade e a pureza dos produtos. Constatou-se ausência das informações obrigatórias em 92,59% das amostras. Dentre os termos vedados, foi comum a sugestão da inexistência de efeitos colaterais ou adversos. Quanto as indicações terapêuticas não se observou padronização técnica dos termos nem comprovação científica para algumas das atividades atribuídas pelos fabricantes. Todas as amostras foram consideradas autênticas com base nos testes fitoquímicos e farmacobotânicos. Na análise da pureza 59,26% das amostras foram reprovadas, devido principalmente ao elevado teor de umidade e cinzas totais. Constata-se que além dos produtos comercializados carecerem de informações e qualidade adequadas, há necessidade urgente de uma fiscalização efetiva por parte dos órgãos competentes.Aiming to evaluate the quality of products made from medicinal plants, there were analyzed ten samples of horsechestnut, eleven samples of lemongrass, and six samples of gotu kola commercialized in pharmacies from the city of Recife (Pernambuco, Brazil, coming from industries of several parts of the country. We analyzed the technical-scientific information on the labels and/or directions according to the requirements and obligations of Brazilian law (laws "RDC 140 of 29/05/2003" and "RDC 102 of 30/11/2000" and to scientific literature embasement. The products' organoleptic characteristics, authenticity, and purity were also evaluated. The absence of obligatory information was verified in 92.59% of the samples. Among the blacked terms, it was common to find products that suggested inexistent collateral or adverse effects. Technical terms were not standardized and the manufacturers did not provide scientific proof for some of the activities credited to the products. All samples were considered authentic based on the phytochemical and pharmacobotanical tests. The purity analysis considered 59.26% of the samples inappropriate, mainly due to the high total levels of humidity and ashes. It was verified that besides the lack of adequate information and quality of the commercialized products, there is an urgent need for an effective inspection by the suitable agencies.

  16. ESSENTIAL OILS OF CYMBOPOGON SP. IN THE CONTROL OF FOODBORNE PATHOGENIC BACTERIA

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    Danilo Florisvaldo BRUGNERA

    2011-08-01

    Full Text Available In this study, the agar well diffusion technique was used to determine the antibacterial activity of Cymbopogon nardus (citronella and Cymbopogon citratus (lemongrass essential oils, which were applied at different concentrations. The bacterial species used were the foodborne pathogens Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Both essential oils presented antibacterial activity in most concentrations tested. The Minimum Inhibitory Concentrations (MICs founded were: 7.81μL/mL (S. aureus and 3.90μL/mL (E. coli and P. aeruginosa, for C. nardus essential oil; and 3.90μL/mL (S. aureus, E. coli and P. aeruginosa, for C. citratus essential oil. The essential oils used were shown as promising natural antibacterials for pathogenic bacteria control in the food industry.

  17. Lemon grass ( Cymbopogon citratus ) essential oil as a potent anti ...

    African Journals Online (AJOL)

    Conclusion: Results of the present study indicate that LGEO has a noteworthy potential for the development of drugs for the treatment of fungal infections and skin inflammation that should be explored in future studies. Keywords: lemon grass; essential oil; antifungal activity; anti-inflammatory effect; citral; aromatherapy ...

  18. Influência da luz e da temperatura sobre a oxidação do óleo essencial de capim-limão (Cymbopogon citratus (D.C.) Stapf)

    OpenAIRE

    Guimarães,Luiz Gustavo de L.; Cardoso,Maria das Graças; Zacaroni,Lidiany M.; Lima,Rafaela K. de; Pimentel,Flávio A.; Morais,Augusto R. de

    2008-01-01

    The identification of the chemical compounds of the essential oil was performed with a gas chromatograph coupled to a mass spectrometer. The oil was left in the presence and absence of light and submitted to different temperatures to evaluate its stability. The yields of the major compounds were evaluated every fifteen days. Citral and myrcene, the major compounds of the essential oil, were degraded over time in both the presence and absence of light, but temperature only influenced the degra...

  19. Influence of metals on essential oil content and composition of lemongrass (Cymbopogon citratus (D.C.) Stapf.) grown under different levels of red mud in sewage sludge amended soil.

    Science.gov (United States)

    Gautam, Meenu; Agrawal, Madhoolika

    2017-05-01

    Lemongrass is a commercially important perennial herb with medicinal value and ability to tolerate high alkaline and saline conditions. Essential oil bearing plants can grow safely in soil contaminated with heavy metals without severe effects on morphology and oil yield. The present study was aimed to assess the essential oil content and composition in lemongrass in response to elevated metals in above-ground plant parts. Pot experiment was conducted for six months using sewage sludge as soil amendment (soil: sludge: 2:1 w/w) followed by red mud treatments (0, 5, 10 and 15% w/w). Garden soil without sludge and red mud was control and there were ten replicates of each treatment. Oil content in leaves was differently affected due to presence of metals in soil under different treatments. Oil content under S RM5 (5% red mud) treatment was raised by 42.9 and 11.5% compared to the control and S RM0 treatment, respectively. Among identified compounds in oil under red mud treatments, 17 compounds contributed more than 90% of total volatiles (citral contributing approximately 70%). Under S RM10 treatment, essential oil showed maximum citral content (75.3%). Contents of Fe, Zn, Cu, Cd, Ni and Pb in above-ground plant parts exceeded, whereas Mn was detected within WHO permissible limits for medicinal plants. However, metal contents in essential oil were well within FSSAI limits for food. The study suggests utilization of 5 and 10% red mud in sludge amended soil for lemongrass cultivation to have better oil yield and quality, without metal contamination. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Primeira ocorrência de ferrugem em capim-limão causada por Puccinia cymbopogonis no Brasil First report of the lemongrass rust fungi caused by Puccinia cymbopogonis in Brazil

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    João Batista Vida

    2006-03-01

    Full Text Available È registrada a primeira ocorrência de ferrugem em capim-limão (Cymbopogon citratus (DC. Stapf, causada por Puccinia cymbopogonis Mass., no Brasil, Estado do Paraná.It is reported the first occurrence of the lemongrass (Cymbopogon citratus (DC. Stapf rust fungi caused by Puccinia cymbopogonis Mass. in Brazil, State of Paraná.

  1. Antimicrobial Effects of Trachyspermum ammi and Cymbopogon ...

    African Journals Online (AJOL)

    The results indicated that 1 % v/w of T. ammi and C. citratus oils prepared in some bases exhibited remarkable antifungal activity with zone inhibition diameters greater than those for standard antifungal agents. The growth of all five fungal strains was inhibited when T. ammi and C. citratus oil were formulated separately in ...

  2. Etude de l'activité antifongique d'extraits de Cymbopogon citratus ...

    African Journals Online (AJOL)

    Cependant, l'introduction des pesticides bio s'avère une alternative judicieuse et moins onéreuse pour la production, d'où l'objectif de notre étude qui était de promouvoir l'efficacité des extrait aqueux et huiles essentiels de quelques plantes locales dans la lutte contre les microorganismes. A travers la méthode de la ...

  3. Etude de l'activité antifongique d'extraits de Cymbopogon citratus ...

    African Journals Online (AJOL)

    1 Institut du Développement Rural, Université polytechnique de Bobo-Dioulasso, 01 BP 1091 Bobo-Dioulasso,. Burkina Faso. ... essentiels de quelques plantes locales dans la lutte contre les microorganismes. ... les concentrations a présenté une forte activité antifongique contre Pyricularia oryzae et un effet réducteur sur.

  4. Essential oil production of lemongrass (Cymbopogon citratus under organic compost containing sewage sludge

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    Júlia V. d'Ávila

    Full Text Available ABSTRACT One of the main urban polluting agents are the sewers, which even with proper treatment end up generating a polluting waste, the sewage sludge. One of the options for the disposal of this sludge is the use in agriculture, due to its high content of organic matter and nutrients. This study aimed to use urban sewage sludge for lemongrass cultivation and essential oil production. The plants were grown in soil containing different organic compost doses (0, 5, 10, 20, 40 and 60 t ha-1, formed from the sewage sludge composting process and waste of urban vegetation pruning. At harvest, plants were analyzed for the concentration of nutrients, chlorophyll content, number of tillers, biomass production, essential oil content and the microbiological quality of the leaves. The results showed that the addition of the compost increased the levels of nutrients in the plants, mainly nitrogen, positively influencing the production of tillers, biomass, chlorophyll contents, yield and essential oil content.

  5. Kajian Aktivitas Antibakteri Minyak Daun Sereh (Cymbopogon citratus pada Adonan Sate Lilit Ikan Laut

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    DewaNyoman Adi Paramartha

    2015-03-01

    Full Text Available Lemongrass is one of the spceies often used in cooking or as traditional medicine.The importance components in lemongrass oil that act as antimicrobial is citral. In this research lemongrass oil isolated by steam distilation method and lemongrass oil were tested against Escherichia coli, Staphylococcus aureus, and Salmonella typhi using the agar diffusion method. Antibacterial activity also evaluated on traditional fish satay dough, and tested its organoleptic value. The result showed that lemongrass oil significantly inhibited E. coli with minimum inhibiting concentration (MIC 0.72 µl/ml and minimum bactericidal concentration (MBC 2.89 µl/ml, S. typhi with MIC 0.65 µl/ml and MBC 2.59 µl/ml, S. aureus with MIC 0.64 µl/ml and MBC 2.57 µl/ml. Antibacterial activity studies of lemongrass oil as potential food aditive was evaluated by adding highest MIC and MBC value (0.72 and 2.89 µl/g on traditional fish satay dough. The result showed that adding lemongrass oil 0.72µl/g is not significantly inhibit nature growing bacteria E. coli, Salmonella, and Staphylococcus on satay dough, but adding 2.89 µl/g lemongras oil only can signigicantly inhibit E. coli, Salmnoella, and Staphylococcus at 0 hours of incubation period, but cannot inhibit it’s log phase up to 24 hours of incubation. Organoleptic of added lemongrass oil on fish satay douh was showed that adding 0.72 µl/g of lemongrass oil was not significant on taste and smell, but adding 2.89 µl/g was significant on taste and smell compared to control.

  6. Identification of geranic acid, a tyrosinase inhibitor in lemongrass (Cymbopogon citratus).

    Science.gov (United States)

    Masuda, Toshiya; Odaka, Yuka; Ogawa, Natsuko; Nakamoto, Katsuo; Kuninaga, Hideki

    2008-01-23

    Lemongrass is a popular Asian herb having a lemon-like flavor. Very recently, potent tyrosinase inhibitory activity has been found in lemongrass in addition to various biological activities reported in the literature. The aim of the present study is to identify the active compounds in the lemongrass. An assay-guided purification revealed that one of the active substances was geranic acid. Geranic acid has two stereoisomers, which are responsible for the trans and cis geometry on the conjugated double bond. Both isomers are present in the active ethyl acetate-soluble extract of the lemongrass, and their IC50 values were calculated to be 0.14 and 2.3 mM, respectively. The structure requirement of geranic acid for the potent tyrosinase inhibitory activity was investigated using geranic acid-related compounds.

  7. Antimicrobial property of lemongrass (Cymbopogon citratus) oil against pathogenic bacteria isolated from pet turtles.

    Science.gov (United States)

    De Silva, B C J; Jung, Won-Gi; Hossain, Sabrina; Wimalasena, S H M P; Pathirana, H N K S; Heo, Gang-Joon

    2017-06-01

    The usage of essential oils as antimicrobial agents is gaining attention. Besides, pet turtles were known to harbor a range of pathogenic bacteria while the turtle keeping is a growing trend worldwide.The current study examined the antimicrobial activity of lemon grass oil (LGO) against seven species of Gram negative bacteria namely; Aeromonas hydrophila , A. caviae , Citrobacter freundii , Salmonella enterica , Edwardsiella tarda , Pseudomonas aeruginosa , and Proteus mirabilis isolated from three popular species of pet turtles. Along with the results of disc diffusion, minimum inhibitory and minimum bactericidal concentration (MIC and MBC) tests, LGO was detected as effective against 6 species of bacteria excluding P. aeruginosa . MIC of LGO for the strains except P. aeruginosa ranged from 0.016 to 0.5% (V/V). The lowest MIC recorded in the E. tarda strain followed by A. hydrophilla , C. freundii , P. mirabilis , and S. enterica . Interestingly, all the bacterial species except E. tarda were showing high multiple antimicrobial resistance (MAR) index values ranging from 0.36 to 0.91 upon the 11 antibiotics tested although they were sensitive to LGO.

  8. Karakterisasi Kemasan Kertas Aktif dengan Penambahan Oleoresin Ampas Destilasi Sereh Dapur (Cymbopogon citratus

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    Lia Umi Khasanah

    2017-03-01

    Full Text Available The aims of this research were to determine the effect of lemongrass distillation dregs oleoresin concentration (0 %, 2 %, 4 %, and 6 % b/b on the active paper packaging characteristics (sensory, water content, thickness, tensile strength, fold endurance and antimicrobial activity, to determine the functional groups of the control and selected active paper packaging, to determine the effect of days of storage (0, 5, 10, 15, and 20 day on the control and selected active paper packaging characteristics (tensile strength, and fold endurance, and to determine antimicrobial activity of the control and selected active paper packaging during 20 days storage. The result showed that the concentration of lemongrass distillation dregs oleoresin significantly affected the color, overall, tensile strength, fold endurance, and antimicrobial activity while did not significantly affected the flavor, texture, water content, and thickness of the active paper packaging. The addition of lemongrass distillation dregs oleoresin increased the water content, thickness, microbial activity, while decreased the panelists preference, tensile strength and fold endurance of the active paper packaging. The spectrum of functional groups of the active paper packaging showed the presence of chitosan, cellulose, tween 80, and lemongrass oleoresin. The storage days had no significant effect on tensile strength and fold endurance of the control and selected active paper packaging. The control and selected active paper packaging were significantly different at each 5 days storage. However the 20 day of storage showed no significant effect on the antimicrobial activity of the control and selected active paper packaging.   ABSTRAK Tujuan dari penelitian ini adalah untuk mengetahui pengaruh konsentrasi oleoresin ampas destilasi sereh dapur (0 %, 2 %, 4 %, dan 6 % b/b terhadap karakteristik kemasan kertas aktif (analisis sensoris, kadar air, ketebalan, ketahanan tarik, ketahanan lipat, dan aktifitas antimikroba, mengetahui gugus fungsi kemasan kertas aktif kontrol dan konsentrasi oleoresin ampas destilasi sereh dapur terpilih, mengetahui pengaruh waktu penyimpanan (0, 5, 10, 15, dan 20 hari terhadap karakteristik kemasan kertas aktif kontrol dan konsentrasi oleoresin ampas destilasi sereh dapur terpilih (uji ketahanan lipat dan ketahanan tarik, dan mengetahui aktivitas antimikroba kemasan kertas aktif kontrol dan konsentrasi oleoresin ampas destilasi sereh dapur terpilih sebelum dan setelah penyimpanan selama 20 hari. Hasil penelitian menunjukkan bahwa konsentrasi oleoresin berpengaruh nyata terhadap warna, overall (penerimaan keseluruhan, ketahanan tarik, ketahanan lipat, dan aktivitas antimikroba tetapi berpengaruh tidak nyata terhadap aroma, tekstur, kadar air, dan ketebalan kemasan kertas aktif. Penambahan oleoresin ampas destilasi sereh dapur meningkatkan kadar air, ketebalan, dan aktivitas antimikroba serta menurunkan ketahanan tarik, ketahanan lipat, dan penerimaan panelis. Kemasan kertas aktif mengandung gugus fungsi selulosa, kitosan, dan tween 80 serta pada kemasan kertas aktif penambahan oleoresin konsentrasi 2 % terdapat gugus fungsi oleoresin sereh dapur. Waktu penyimpanan tidak berpengaruh secara nyata terhadap ketahanan tarik dan ketahanan lipat kemasan kertas aktif kontrol dan konsentrasi terpilih. Kemasan kertas aktif kontrol dengan kemasan kertas aktif penambahan oleoresin konsentrasi 2 % berbeda nyata di setiap 5 hari penyimpanan. Namun, penyimpanan selama 20 hari tidak berpengaruh secara nyata terhadap aktivitas antimikroba kemasan kertas aktif kontrol dan konsentrasi terpilih.

  9. Determinação da qualidade microbiológica e físico-química de chás de Cymbopogon citratus (D.C Stapf (capim-limão = Evaluation of the microbiological and physical-chemical qualities of lemongrass tea

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    Eliane Carneiro Gomes

    2008-01-01

    Full Text Available Em função do grande volume de produção e comercialização do capim-limão, estima-se que uma contaminação microbiológica deste produto possa representar importante risco para a saúde pública. Esta pesquisa visou avaliar marcas de chá de capimlimão, em relação às qualidades microbiológica e físico-química, tendo como base alegislação brasileira do Ministério da Saúde. Nenhuma das amostras apresentou Salmonella sp., porém em 50% delas, houve presença de coliformes a 35ºC. Em três amostras, evidenciaram-se coliformes a 45ºC, com presença de Escherichia coli em uma destas. 81,25%das amostras apresentaram bolores e leveduras, porém sem relação direta com os teores de umidade observados. Dentre os fungos presentes, identificou-se Aspergillus niger, no entanto sem produção de aflatoxinas. Todos infusos analisados negativaram a contaminação evidenciada nos testes com o produto seco. Os resultados indicaram possíveis falhas nos procedimentos pós-colheita e de comercialização. A implementação do Sistema APPCC (HACCP poderia substancialmente minimizar esta contaminação.Considering the great volume of lemongrass production andcommercialization, it is estimated that a potential microbiological contamination of this product could represent an important hazard to public health. This study was performed to evaluate different brands of lemongrass tea, regarding their microbiological and physicalchemical quality, based on the legislation of the Brazilian Health Ministry. No traces of Salmonella sp. were found, but in 50% of samples, the presence of coliforms was detected at 35ºC. Three samples presented coliforms at 45ºC, with Escherichia coli found in one of them. 81.25% of samples presented molds and yeasts. Among the fungi present, Aspergillus niger was identified, but aflatoxins were absent. None of the infusions analyzed presented the contamination evidenced in the dry product. The results obtained may be indicative of failure in procedures of postharvest and commercialization. The implementation of a hazard analysis and critical control point system (HACCP could reduce this contamination substantially.

  10. Short Communication: Association of Cymbopogon plurinodis with ...

    African Journals Online (AJOL)

    In a camp, typical of the Sourish Mixed Bushveld, a marked decrease in the abundance of Cymbopogon plurinodis along a soil gradient from high to low clay content was found. The association appears to be independent of the grazing treatment over a 51-year period as the population size of C. plurinodis has remained ...

  11. Habitat factors influencing the distribution of Cymbopogon validus in ...

    African Journals Online (AJOL)

    Habitat factors influencing the distribution of Cymbopogon validus in Mkambati Game Reserve, Transkei. ... disturbance; game reserve; grassland; grasslands; habitat conditions; habitat factors; mkambati game ... AJOL African Journals Online.

  12. Influence of extraction methodologies on the analysis of five major volatile aromatic compounds of citronella grass (Cymbopogon nardus) and lemongrass (Cymbopogon citratus) grown in Thailand.

    Science.gov (United States)

    Chanthai, Saksit; Prachakoll, Sujitra; Ruangviriyachai, Chalerm; Luthria, Devanand L

    2012-01-01

    This paper deals with the systematic comparison of extraction of major volatile aromatic compounds (VACs) of citronella grass and lemongrass by classical microhydrodistillation (MHD), as well as modern accelerated solvent extraction (ASE). Sixteen VACs were identified by GC/MS. GC-flame ionization detection was used for the quantification of five VACs (citronellal, citronellol, geraniol, citral, and eugenol) to compare the extraction efficiency of the two different methods. Linear range, LOD, and LOQ were calculated for the five VACs. Intraday and interday precisions for the analysis of VACs were determined for each sample. The extraction recovery, as calculated by a spiking experiment with known standards of VACs, by ASE and MHD ranged from 64.9 to 91.2% and 74.3 to 95.2%, respectively. The extraction efficiency of the VACs was compared for three solvents of varying polarities (hexane, dichloromethane, and methanol), seven different temperatures (ranging from 40 to 160 degrees C, with a gradual increment of 20 degrees C), five time periods (from 1 to 10 min), and three cycles (1, 2, and 3 repeated extractions). Optimum extraction yields of VACs were obtained when extractions were carried out for 7 min with dichloromethane and two extraction cycles at 120 degrees C. The results showed that the ASE technique is more efficient than MHD, as it results in improved yields and significant reduction in extraction time with automated extraction capabilities.

  13. Essential oil biosynthesis and regulation in the genus Cymbopogon.

    Science.gov (United States)

    Ganjewala, Deepak; Luthra, Rajesh

    2010-01-01

    Essential oils distilled from Cymbopogon species are of immense commercial value as flavors and fragrances in the perfumery, cosmetics, soaps, and detergents and in pharmaceutical industries. Two major constituents of the essential oil, geraniol and citral, due to their specific rose and lemon like aromas are widely used as flavors, fragrances and cosmetics. Citral is also used for the synthesis of vitamin A and ionones (for example, beta-ionone, methyl ionone). Moreover, Cymbopogon essential oils and constituents possess many useful biological activities including cytotoxic, anti-inflammatory and antioxidant. Despite the immense commercial and biological significance of the Cymbopogon essential oils, little is known about their biosynthesis and regulatory mechanisms. So far it is known that essential oils are biosynthesized via the classical acetate-MVA route and existence of a newly discovered MEP pathway in Cymbopogon remains as a topic for investigation. The aim of the present review is to discuss the biosynthesis and regulation of essential oils in the genus Cymbopogon with given emphasis to two elite members, lemongrass (C. flexuosus Nees ex Steud) and palmarosa (C. martinii Roxb.). This article highlights the work done so far towards understanding of essential oil biosynthesis and regulation in the genus Cymbopogon. Also, based on our experiences with Cymbopogon species, we would like to propose C. flexuosus as a model system for the study of essential oil metabolism beyond the much studied plant family Lamiaceae.

  14. Short Communication: Response of Cymbopogon validus tillers to ...

    African Journals Online (AJOL)

    The response of tagged Cymbopogon validus tillers to three clipping frequencies indicated that this species is intolerant of severe and frequent defoliation. This could account for its decreased abundance in heavily-grazed areas in and around Mkambati Game Reserve, Transkei.Language: English. Keywords: abundance ...

  15. Development of lignin in Themeda triandra, Cymbopogon plurinodis ...

    African Journals Online (AJOL)

    The amount and distribution of lignin in three grass species was determined. Two climax species, Themeda triandra and Cymbopogon plurinodis and one pioneer species, Eragrostis lehmanniana were used in the investigation. Leaf samples of the three grass species were taken at four stages of growth and samples of the ...

  16. Bactericidal activity of herbal volatile oil extracts against multidrug resistant Acinetobacter baumannii

    OpenAIRE

    Amornrat Intorasoot; Piyaorn Chornchoem; Siriwoot Sookkhee; Sorasak Intorasoot

    2017-01-01

    Aim: To investigate the antibacterial activity of ten volatile oils extracted from medicinal plants, including galangal (Alpinia galanga Linn.), ginger (Zingiber officinale), plai (Zingiber cassumunar Roxb.), lime (Citrus aurantifolia), kaffir lime (Citrus hystrix DC.), sweet basil (Ocimum basilicum Linn.), tree basil (Ocimum gratissimum), lemongrass (Cymbopogon citratus DC.), clove (Syzygium aromaticum) and cinnamon (Cinnamomum verum) against four standard strains of Staphylococcus aureus, E...

  17. PEMANFAATAN SEREH (Cymbopogon Cytratus DALAM MENURUNKAN BAU PADA PUPUK ORGANIK CAIR DAN POTENSINYA DALAM MENINGKATKAN PRODUKSI TANAMAN CABAI (Capsicum Annum

    Directory of Open Access Journals (Sweden)

    Nurhasanah Nurhasanah

    2013-09-01

    Full Text Available Research in the use of lemongrass (Cymbopogon citratus to reduce odors in liquid organic fertilizer has been conducted in Bogor for 6 months. This study begin with a liquid organic fertilizer produced from 1 kg of shrimp waste, 1 kg of maize, 1 kg of bean sprouts, 10 liters of coconut water, 500 ml of EM4 and 500 g of sugar through fermentation process for 6 weeks. Then the result of liquid organic fertilizer was added by an ingredient lemongrass as deodorizing with doses of 0, 10%, 20% and 30% (w/v. After that it is fermented for 2 weeks. The next stage was the application of liquid organic fertilizer as a foliar fertilizer at chillies (Capsicum annum planting using a completely randomized design (CRD 1 factors type of using liquid organic fertilizer (control, liquid organic fertilizer without lemongrass, liquid organic fertilizer + 10% lemongrass, liquid organic fertilizer + 20% lemongrass and liquid organic fertilizer + 30% lemongrass respectively at doses of 0, 6, 12 and 18 ppm. The parameters measured were odor (NH3 and H2S, levels of macro nutrients (N, P, K, Ca, Mg, and S and micro nutrients (Cu, Zn, Mn, and Fe after fermenting process, and the production of crops (fruit number and fruit weight after planting. Research results show that the higher dose of lemongrass added cause levels of odor (NH3 and H2S in the liquid organic fertilizer decreased and content of macro nutrients, micro nutrients, and phytohormones increased. The planting results indicate liquid organic fertilizer which added 20% lemongrass in a dose of 12 ppm was the optimal dose in increasing crop production. Penelitian penggunaan sereh (Cymbopogon citratus dalam menurunkan bau pada pupuk organik cair telah dilakukan di Bogor selama 6 bulan. Penelitian ini diawali dengan membuat pupuk organik cair yang dihasilkan dari 1 kg limbah udang, 1 kg jagung, 1 kg touge, 10 Liter air kelapa, 500 ml EM4 dan 500 g gula pasir melalui proses fermentasi selama 6 minggu. Kemudian pada

  18. Advanced DC/DC converters

    CERN Document Server

    Luo, Fang Lin

    2003-01-01

    DC/DC conversion techniques have undergone rapid development in recent decades. With the pioneering work of these authors, DC/DC converters have now moved into their sixth generation. This book offers a concise, practical presentation of DC/DC converters, summarizing the spectrum of conversion tecnologies and presentingmany new ideas and more than 100 new topologies. Nowhere else in the literature are DC/DC converters so logically sorted and systematically introduced, and nowhere else can readers find detailed information on prototype topologies that represent a major contribution to modern power engineering. More than 320 figures, 60 tables, and 500 formulae facilitate understand and provide precise data.

  19. Study of the chemical composition of essential oils and floral waters ...

    African Journals Online (AJOL)

    This work aimed to study the chemical composition of essential oils and floral waters of Cymbopogon citratus (DC.) Stapf (Poaceae) from Senegal. The plants were collected in two different localities, Dakar and. Kaolack. The extracts were obtained by steam distillation from both fresh and dried plants and analyses carried.

  20. Study of the chemical composition of essential oils and floral waters ...

    African Journals Online (AJOL)

    This work aimed to study the chemical composition of essential oils and floral waters of Cymbopogon citratus (DC.) Stapf (Poaceae) from Senegal. The plants were collected in two different localities, Dakar and Kaolack. The extracts were obtained by steam distillation from both fresh and dried plants and analyses carried ...

  1. Anti-dandruff Hair Tonic Containing Lemongrass (Cymbopogon flexuosus) Oil.

    Science.gov (United States)

    Chaisripipat, Wannee; Lourith, Nattaya; Kanlayavattanakul, Mayuree

    2015-01-01

    Natural remedies for treating dandruff are becoming popular. A randomized, double-blind, placebo-controlled, split-head efficacy evaluation was conducted 30 Thai volunteers aged 20-60 years experiencing dandruff measured at level 3 on D-Squame® scale. An easy to use hair tonic containing essential oil of lemongrass (Cymbopogon flexuosus) active against lipophilic yeasts was developed and then evaluated for efficacy and preference. The base formulation with the significantly highest preference (p lemongrass oil hair tonics with 5, 10, or 15% reduced dandruff significant (p lemongrass oil seems to be the most effective preparation. © 2015 S. Karger GmbH, Freiburg.

  2. FORMULATION OF NANOEMULSION MOUTHWASH COMBINATION OF LEMONGRASS OIL (Cymbopogon citratus AND KAFFIR LIME OIL (Citrus hystrix FOR ANTICANDIDIASIS AGAINST Candida albicans ATCC 10231

    Directory of Open Access Journals (Sweden)

    Meta Juniatik

    2017-04-01

    Full Text Available Candidiasis is a fungal infection disease that still become health problem in Indonesia, especially oral candidiasis that largerly caused by Candida albicans abnormal growth on oral cavity. Lemongrass oil and kaffir lime oil have been proven to have antifungal activity against Candida albicans. The composition of limonen, α-terpineol, sitronelil acetate, terpineol, β-pinene, on kaffir lime oil and citronelal on lemongrass oil make the combination of both oils have the potential as an alternative theraphy for oral candidiasis. It formulates in the form of nanoemulsion mouthwash. Nanoemulsion is chosen because it has some advantages like clear, stable, and increasing the antifungal activity of lemongrass oil and kaffir lime oil. The study begins with plants determination, essential oils charecterization tests (solubility, refractative index, and specific gravity, and essential oil content analysis by GC-MS. Nanoemulision formulates by water titration method. Optimization of oil mix and VCO do to get a clear and stable nanoemulsion. The best formula is characterized (transmittance, particle size, viscosity, zeta potential, and stability test, then analyze the essential oil chemical compounds in the optimum formula and test the inhibitory effect of the formula by microdilution method. Inhibiton data analysis use One Way ANOVA. Based on the results of the study, 0.4 % oil mix, 3.6 % VCO, 17.3 % tween 80, 8.7 % PEG 400 dan 70 % water is the best formula that can form a nanoemulsion system with an average particle size 21,4 nm, low viscosity, low zeta potential and stable during freez-thaw storage. Nanoemulsion significantly has inhibitory effect more effective than positive control.

  3. Antimicrobial action and anti-corrosion effect against sulfate reducing bacteria by lemongrass (Cymbopogon citratus) essential oil and its major component, the citral.

    Science.gov (United States)

    Korenblum, Elisa; Regina de Vasconcelos Goulart, Fátima; de Almeida Rodrigues, Igor; Abreu, Fernanda; Lins, Ulysses; Alves, Péricles Barreto; Blank, Arie Fitzgerald; Valoni, Erika; Sebastián, Gina V; Alviano, Daniela Sales; Alviano, Celuta Sales; Seldin, Lucy

    2013-08-10

    The anti-corrosion effect and the antimicrobial activity of lemongrass essential oil (LEO) against the planktonic and sessile growth of a sulfate reducing bacterium (SRB) were evaluated. Minimum inhibitory concentration (MIC) of LEO and its major component, the citral, was 0.17 mg ml-1. In addition, both LEO and citral showed an immediate killing effect against SRB in liquid medium, suggesting that citral is responsible for the antimicrobial activity of LEO against SRB. Transmission electron microscopy revealed that the MIC of LEO caused discernible cell membrane alterations and formed electron-dense inclusions. Neither biofilm formation nor corrosion was observed on carbon steel coupons after LEO treatment. LEO was effective for the control of the planktonic and sessile SRB growth and for the protection of carbon steel coupons against biocorrosion. The application of LEO as a potential biocide for SRB growth control in petroleum reservoirs and, consequently, for souring prevention, and/or as a coating protection against biocorrosion is of great interest for the petroleum industries.

  4. Antimicrobial action and anti-corrosion effect against sulfate reducing bacteria by lemongrass (Cymbopogon citratus) essential oil and its major component, the citral

    Science.gov (United States)

    2013-01-01

    The anti-corrosion effect and the antimicrobial activity of lemongrass essential oil (LEO) against the planktonic and sessile growth of a sulfate reducing bacterium (SRB) were evaluated. Minimum inhibitory concentration (MIC) of LEO and its major component, the citral, was 0.17 mg ml-1. In addition, both LEO and citral showed an immediate killing effect against SRB in liquid medium, suggesting that citral is responsible for the antimicrobial activity of LEO against SRB. Transmission electron microscopy revealed that the MIC of LEO caused discernible cell membrane alterations and formed electron-dense inclusions. Neither biofilm formation nor corrosion was observed on carbon steel coupons after LEO treatment. LEO was effective for the control of the planktonic and sessile SRB growth and for the protection of carbon steel coupons against biocorrosion. The application of LEO as a potential biocide for SRB growth control in petroleum reservoirs and, consequently, for souring prevention, and/or as a coating protection against biocorrosion is of great interest for the petroleum industries. PMID:23938023

  5. Milliwatt dc/dc Inverter

    Science.gov (United States)

    Mclyman, C. W.

    1983-01-01

    Compact dc/dc inverter uses single integrated-circuit package containing six inverter gates that generate and amplify 100-kHz square-wave switching signal. Square-wave switching inverts 10-volt local power to isolated voltage at another desired level. Relatively high operating frequency reduces size of filter capacitors required, resulting in small package unit.

  6. Bactericidal activity of herbal volatile oil extracts against multidrug-resistant Acinetobacter baumannii

    OpenAIRE

    Intorasoot, Amornrat; Chornchoem, Piyaorn; Sookkhee, Siriwoot; Intorasoot, Sorasak

    2017-01-01

    Aim: The aim of the study is to investigate the antibacterial activity of 10 volatile oils extracted from medicinal plants, including galangal (Alpinia galanga Linn.), ginger (Zingiber officinale), plai (Zingiber cassumunar Roxb.), lime (Citrus aurantifolia), kaffir lime (Citrus hystrix DC.), sweet basil (Ocimum basilicum Linn.), tree basil (Ocimum gratissimum), lemongrass (Cymbopogon citratus DC.), clove (Syzygium aromaticum), and cinnamon (Cinnamomum verum) against four standard strains of ...

  7. Ethanol and High-Value Terpene Co-Production from Lignocellulosic Biomass of Cymbopogon flexuosus and Cymbopogon martinii.

    Directory of Open Access Journals (Sweden)

    Blake L Joyce

    Full Text Available Cymbopogon flexuosus, lemongrass, and C. martinii, palmarosa, are perennial grasses grown to produce essential oils for the fragrance industry. The objectives of this study were (1 to evaluate biomass and oil yields as a function of nitrogen and sulfur fertilization, and (2 to characterize their utility for lignocellulosic ethanol compared to Panicum virgatum (switchgrass. Mean biomass yields were 12.83 Mg lemongrass ha-1 and 15.11 Mg palmarosa ha-1 during the second harvest year resulting in theoretical biofuel yields of 2541 and 2569 L ethanol ha-1 respectively compared to reported 1749-3691 L ethanol ha-1 for switchgrass. Pretreated lemongrass yielded 198 mL ethanol (g biomass-1 and pretreated palmarosa yielded 170 mL ethanol (g biomass-1. Additionally, lemongrass yielded 85.7 kg essential oil ha-1 and palmarosa yielded 67.0 kg ha-1 with an estimated value of USD $857 and $1005 ha-1. These data suggest that dual-use crops such as lemongrass and palmarosa may increase the economic viability of lignocellulosic biofuels.

  8. Ethanol and High-Value Terpene Co-Production from Lignocellulosic Biomass of Cymbopogon flexuosus and Cymbopogon martinii.

    Science.gov (United States)

    Joyce, Blake L; Zheljazkov, Valtcho D; Sykes, Robert; Cantrell, Charles L; Hamilton, Choo; Mann, David G J; Rodriguez, Miguel; Mielenz, Jonathan R; Astatkie, Tess; Stewart, C Neal

    2015-01-01

    Cymbopogon flexuosus, lemongrass, and C. martinii, palmarosa, are perennial grasses grown to produce essential oils for the fragrance industry. The objectives of this study were (1) to evaluate biomass and oil yields as a function of nitrogen and sulfur fertilization, and (2) to characterize their utility for lignocellulosic ethanol compared to Panicum virgatum (switchgrass). Mean biomass yields were 12.83 Mg lemongrass ha-1 and 15.11 Mg palmarosa ha-1 during the second harvest year resulting in theoretical biofuel yields of 2541 and 2569 L ethanol ha-1 respectively compared to reported 1749-3691 L ethanol ha-1 for switchgrass. Pretreated lemongrass yielded 198 mL ethanol (g biomass)-1 and pretreated palmarosa yielded 170 mL ethanol (g biomass)-1. Additionally, lemongrass yielded 85.7 kg essential oil ha-1 and palmarosa yielded 67.0 kg ha-1 with an estimated value of USD $857 and $1005 ha-1. These data suggest that dual-use crops such as lemongrass and palmarosa may increase the economic viability of lignocellulosic biofuels.

  9. The chemical composition of the essential oil of Cymbopogon flexuosus (Steud) Wats. growing in Northeast India

    NARCIS (Netherlands)

    Nath, S.C.; Saha, B.N.; Bordoloi, D.N.; Mathur, Raj K.; Leclercq, P.A.

    1994-01-01

    The essential oil of Cymbopogon flexuosus obtained by hydrodistn. of grass was analyzed by GC/MS. Twenty-five oil components have been identified, which constituted 96.4% of the oil. The major components were geraniol (30.5%), citronellol (24.1%), neural (10.3%) and geranial (13.6%)

  10. Essential oil of Cymbopogon khasianus (Munro ex Hack.) Bor from Northeastern India

    NARCIS (Netherlands)

    Choudhury, S.N.; Leclercq, P.A.

    1995-01-01

    The essential oil obtained by hydrodistillation of the fresh leaves of Cymbopogon khasianus collected from the northeastern region in India was analyzed by GC/MS. It was found that the major components were geraniol (78.4%), geranyl acetate (7.3%), linalool (2.2%) and geraniol (1.6%).

  11. The essential oil of a variant of Cymbopogon flexuosus (Nees ex Steud) Wats. from Northeast India

    NARCIS (Netherlands)

    Sarma, K.K.; Nath, S.C.; Leclercq, P.A.

    1999-01-01

    The chemical composition of the oil of a phenotypic variant of Cymbopogon flexuosus (Nees ex Steud) Wats., growing wild in northeast India, was investigated by GC and GClMS. Fifty compounds, representing 98.3% of the oil were identified. The major constituent was elemicin (53.0%) while other

  12. A Unidirectional DC-DC Autotransformer for DC Grid Application

    Directory of Open Access Journals (Sweden)

    Meng Zhou

    2018-03-01

    Full Text Available Conventional unidirectional DC-DC converters for DC grid application employ DC-AC-DC two-stage conversion technology and suffer from high converter cost and power loss. To solve these issues, a unidirectional step-up DC-DC autotransformer (UUDAT and a unidirectional step-down DC-DC autotransformer (DUDAT are studied. The UUDAT and DUDAT are composed of a series connection of diode bridges and voltage source converters. Topologies of UUDAT and DUDAT are detailed. The harmonic and un-controllability issues are discussed. Control and possible application scenarios for UUDAT and DUDAT are depicted. DC fault isolation mechanism and the methods of dimensioning the voltage and power ratings of the components in UUDAT and DUDAT are studied. Extensive simulations on power system level and experiments on a UUDAT and DUDAT prototype verified their technical feasibility.

  13. Step-Up DC-DC converters

    DEFF Research Database (Denmark)

    Forouzesh, Mojtaba; Siwakoti, Yam P.; Gorji, Saman A.

    2017-01-01

    on the general law and framework of the development of next-generation step-up dc-dc converters, this paper aims to comprehensively review and classify various step-up dc-dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage...

  14. An assessment on performance, emission and combustion characteristics of single cylinder diesel engine powered by Cymbopogon flexuosus biofuel

    International Nuclear Information System (INIS)

    Dhinesh, B.; Isaac JoshuaRamesh Lalvani, J.; Parthasarathy, M.; Annamalai, K.

    2016-01-01

    Highlights: • Cymbopogon Flexuosus biofuel is used as an alternative energy source. • Cymbopogon flexuosus biofuel 20% + Diesel 80% blend profile stayed close to diesel. • Resulting in higher thermal efficiency and reduced fuel consumption. • Reduced hydrocarbon, carbon monoxide and smoke emission. • Oxides of nitrogen and carbon di-oxide emission was marginally higher. - Abstract: The novelty of this manuscript is that it discusses about the experimental analysis of a new biofuel feedstock as an alternative fuel that has not drawn much attention among the researchers. An exploration for a new biofuel feedstock resulted in Cymbopogon flexuosus as an alternative energy source. Raw oil of Cymbopogon flexuosus was obtained through steam distillation process. Cymbopogon flexuosus biofuel was blended with diesel fuel in various proportions on volume basis, namely 10, 20, 30, 40, and 100 percent and its properties were assessed according to American Society for Testing and Materials standards. The considered test fuel was experimentally analysed in a single cylinder diesel engine at 1500 rpm for its performance, emission and combustion characteristics. Among various blends, Fuel blend of Cymbopogon flexuosus biofuel 20% + diesel 80% fuel profile stayed close to diesel fuel resulting in higher thermal efficiency and lower hydrocarbon, carbon monoxide, and smoke emission. However, oxides of nitrogen and carbon dioxide emission was marginally higher for the test fuel considered. Cylinder pressure and heat release rate curves were lower at full load condition as compared with diesel fuel. Against the grim background of fossil fuel depletion, Fuel blend of Cymbopogon flexuosus biofuel 20% + diesel 80% fuel acts as a promising alternative fuel and brings hope to the nation as well as the research world.

  15. Attractiveness of essential oils of three Cymbopogon species to Tribolium castaneum (Herbst adults

    Directory of Open Access Journals (Sweden)

    Đukić Nikola

    2016-01-01

    Full Text Available Behavior bioassays were conducted in the laboratory (23 ± 1°C and 50 ± 5% r.h. using the olfactometer to determine the effects of essential oils of three plant species in the Cymbopogon genus (Lemongrass, Cymbopogon nervatus, C. proximus and C. schoenanthus, on adults of Tribolium castaneum. The effect of essential oils was compared to a commercial biopesticide based on azadirachtin at three concentrations (0.0001, 0.001 and 0.01%. The results showed that all essential oils and the azadirachtin-based biopesticide had significant (p <0.05 repellent effects on T. castaneum adults at all tested concentrations, except C. proximus essential oil which showed a neutral effect at the lowest concentration. The highest concentrations of the essential oils of C. nervatus and C. proximus had significantly stronger repellent effects (p <0.05 than the lowest concentration. At the concentrations of 0.0001 and 0.001% all tested essential oils and azadirachtin showed a similar repellent effect without statistically significant difference, whereas the oil of C. nervatus had the highest repellent effect on adults of T. castaneum at the 0.01% concentration. Considering all tested variations, the essential oils of plants of the genus Cymbopogon showed similar or stronger repellent effects on T. castaneum adults than the biopesticide based on azadirachtin.

  16. DC Home Appliances for DC Distribution System

    Directory of Open Access Journals (Sweden)

    MUHAMMAD KAMRAN

    2017-10-01

    Full Text Available This paper strengthens the idea of DC distribution system for DC microgrid consisting of a building of 50 apartments. Since the war of currents AC system has been dominant because of the paucity of research in the protection of the DC system. Now with the advance research in power electronics material and components, generation of electricity is inherently DC as by solar PV, fuel cell and thermoelectric generator that eliminates the rectification process. Transformers are replaced by the power electronics buck-boost converters. DC circuit breakers have solved the protection problems for both DC transmission and distribution system. In this paper 308V DC microgrid is proposed and home appliances (DC internal are modified to operate on 48V DC from DC distribution line. Instead of using universal and induction motors in rotary appliances, BLDC (Brushless DC motors are proposed that are highly efficient with minimum electro-mechanical and no commutation losses. Proposed DC system reduces the power conversion stages, hence diminishes the associated power losses and standby losses that boost the overall system efficiency. So in view of all this a conventional AC system can be replaced by a DC system that has many advantages by cost as well as by performance

  17. Step-Up DC-DC converters

    DEFF Research Database (Denmark)

    Forouzesh, Mojtaba; Siwakoti, Yam P.; Gorji, Saman A.

    2017-01-01

    on the general law and framework of the development of next-generation step-up dc-dc converters, this paper aims to comprehensively review and classify various step-up dc-dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage......DC-DC converters with voltage boost capability are widely used in a large number of power conversion applications, from fraction-of-volt to tens of thousands of volts at power levels from milliwatts to megawatts. The literature has reported on various voltage-boosting techniques, in which......-boosting techniques and associated converters are discussed in detail. Finally, broad applications of dc-dc converters are presented and summarized with comparative study of different voltage-boosting techniques....

  18. DC electric springs with DC/DC converters

    DEFF Research Database (Denmark)

    Wang, Qingsong; Cheng, Ming; Jiang, Yunlei

    2016-01-01

    The concept of DC electric spring (DCES) was recently proposed to solve the stability issue caused by integrating intermittent renewable energy sources (RESs) to DC microgrids. In this paper, a new topology of DCES is proposed based on DC/DC converters. The proposed DCES consists of a bi-directio......The concept of DC electric spring (DCES) was recently proposed to solve the stability issue caused by integrating intermittent renewable energy sources (RESs) to DC microgrids. In this paper, a new topology of DCES is proposed based on DC/DC converters. The proposed DCES consists of a bi...... and/or constant discharging for batteries is adopted and four operating modes are analyzed as charging-positive, charging-negative, discharging-positive and discharging-negative modes. An additional mechanism for fast charging or fast discharging is also designed to secure normal operation...... of batteries. With the proposed DCES, the power fluctuations due to intermittent RESs can be passed to non-critical loads (NCLs) and batteries while power on critical loads (CLs) is kept stable. This is possibly the first attempt to design a DCES with only DC/DC converters. The performances of the proposed...

  19. Photosynthetic Rates of Citronella and Lemongrass 1

    Science.gov (United States)

    Herath, H. M. Walter; Ormrod, Douglas P.

    1979-01-01

    Ten selections of citronella (Cymbopogon nardus [L.] Rendle) were grown at 32/27, 27/21, or 15/10 C day/night temperatures, and plants from three populations of lemongrass (Cymbopogon citratus [D.C.] Stapf from Japan or Sri Lanka and Cymbopogon flexuosus [D.C.] Stapf from India) were grown at 8- or 15-hour photoperiods. Net photosynthetic rates of mature leaves were measured in a controlled environment at 25 C and 260 microeinsteins per meter2 per second. Rates declined with increasing leaf age, and from the tip to the base of the leaf blade. Rates for citronella leaves grown at 15/10 C were extremely low for all selections. Highest rates of net photosynthesis were recorded for four selections grown at 27/21 C and for two selections grown at 32/27 C. Lemongrass grown at 8-hour photoperiod had higher photosynthetic rates than that grown at 15-hour photoperiod. PMID:16660737

  20. Carbon Dioxide Compensation Values in Citronella and Lemongrass 1

    Science.gov (United States)

    Herath, H. M. Walter; Ormrod, Douglas P.

    1977-01-01

    Carbon dioxide compensation values of mature leaves from 10 selections of citronella (Cymbopogon nardus [L.] Rendle) grown at 32/27 or 27/21 C day/night temperatures and three strains of lemongrass (Cymbopogon citratus [D.C.] Stapf. and Cymbopogon flexuosus [D.C.] Stapf.) grown at 8- or 15-hour photoperiods were measured in a controlled environment at 25 C. All leaves had low compensation values but citronella varied from 1.3 to 9.7 μl/liter and lemongrass from 0.7 to 3.5 μl/liter. Lower growing temperature generally resulted in lower compensation values for citronella but there was no consistent photoperiod effect on lemongrass. PMID:16659935

  1. A resonant dc-dc power converter assembly

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a resonant DC-DC power converter assembly comprising a first resonant DC-DC power converter and a second resonant DC-DC power converter having identical circuit topologies. A first inductor of the first resonant DC-DC power converter and a second inductor of the s......The present invention relates to a resonant DC-DC power converter assembly comprising a first resonant DC-DC power converter and a second resonant DC-DC power converter having identical circuit topologies. A first inductor of the first resonant DC-DC power converter and a second inductor...... of the second resonant DC-DC power converter are configured for magnetically coupling the first and second resonant DC-DC power converters to each other to forcing substantially 180 degrees phase shift, or forcing substantially 0 degree phase shift, between corresponding resonant voltage waveforms of the first...

  2. IGBT Based DC/DC Converter

    Directory of Open Access Journals (Sweden)

    M. Akherraz

    1997-12-01

    Full Text Available This paper presents an in-depth analytical and experimental investigation of an indirect DC-DC converter. The DC-AC conversion is a full bridge based on IGBT power modules, and the AC-DC conversion is done via a high  frequency AC link and a first diode bridge. The AC link, which consists of snubbing capacitors and a variable air-gap transformer, is analytically designed to fulfill Zero Voltage commutation requirement. The proposed converter is simulated using PSPICE and a prototype is designed built and tested in the laboratory. PSPICE simulation and experimental results are presented and compared.

  3. A resonant dc-dc power converter assembly

    OpenAIRE

    Madsen, Mickey Pierre

    2015-01-01

    The present invention relates to a resonant DC-DC power converter assembly comprising a first resonant DC-DC power converter and a second resonant DC-DC power converter having identical circuit topologies. A first inductor of the first resonant DC-DC power converter and a second inductor of the second resonant DC-DC power converter are configured for magnetically coupling the first and second resonant DC-DC power converters to each other to forcing substantially 180 degrees phase shift, or fo...

  4. Chemical composition and spasmolytic activity of Cymbopogon schoenanthus (L. Spreng. (Poaceae essential oil from Sudan

    Directory of Open Access Journals (Sweden)

    Pavlović Ivan

    2017-01-01

    Full Text Available The plants of genus Cymbopogon are well known for their use in traditional medicine and for their high content of essential oils that are widely used as flavoring agents, fragrances, cosmetics, and pharmaceuticals. Essential oils isolated from the dried stems and inflorescence of cultivated Cymbopogon schoenanthus (L. Spreng. (Poaceae collected from Khartoum state (Sudan in two periods were studied. The results of chemical analysis of C. schoenanthus revealed that this plant is rich in essential oil which is a valuable source of the commercially important monoterpene, piperitone (47.7-71.5%. Other abundant constituents of the oils were intermedeol (6.1-17.3%, δ-2-carene (4.5-10.0% and elemol (2.7-9.0%. The essential oil from the inflorescence was tested for spasmolytic activity using three different experimental models: against spontaneous contractions, contractions induced with acetylcholine and contractions induced with potassium chloride. The oil exhibited strong, significant and dose-dependent spasmolytic activity, indicating the possibility for further investigations of this essential oil for its medicinal purposes or application in food industry. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no.173021 and Grant no. III41018

  5. Evaluación de los parámetros de crecimiento de alevines de tilapia roja (Oreochromis sp.) con dietas enriquecidas con dos aceites esenciales : cúrcuma (curcuma longa) y hierba luisa (cymbopogon citratus)

    OpenAIRE

    Salazar Almeida, Carlos Gabriel; Flores Vallejo, Carla Pamela

    2015-01-01

    The production of red tilapia (Oreochromis sp.) is a very important industry in the Ecuador, so it is necessary to make constant innovations that help improve productivity. Currently has encouraged the use of natural extracts to enhance the growth and survival of fish. For this purpose it was decided to evaluate the essential oils of Turmeric and Lemongrass added to food in a concentration of 0.4% w / w with 8 experimental units each one with 20 fingerlings, located in the laboratories of the...

  6. Full range ZVS DC-DC converter

    International Nuclear Information System (INIS)

    Upadhyay, Rinki; Badapanda, M.K.; Hannurkar, P.R.

    2011-01-01

    A 500 V, 24 Amp DC-DC converter with digital signal processor (DSP) based control and protection has been designed, fabricated and tested. Its power circuit consists of IGBT based single phase inverter bridge, ferrite transformer and diode rectifier. All IGBTs in the inverter bridge are operated in zero voltage switching (ZVS) mode to minimize switching losses thereby increasing the efficiency of the converter significantly. The efficiency of this converter is measured to be greater than 97% at full load. In a conventional full bridge inverter, typically ZVS is achieved under full load condition while at light load ZVS is lost. An auxiliary LC circuit has been intentionally incorporated in this converter to achieve ZVS even at light loaded conditions. Detailed simulation of the converter circuit is carried out and crucial waveforms have been presented in this paper. Microchip make dsPIC30F2020 DSP is employed to provide phase shifted PWMs to IGBTs in the inverter bridge. All the crucial parameters are also monitored by this DSP and in case of any unfavorable conditions, the converter is tripped off. Suitable experiments were carried out in this DC-DC converter under different loaded conditions and a close match between the simulated and experimental results were obtained. Such DC-DC converters can be connected in series or parallel for the development of solid state modular power supplies for various applications. (author)

  7. ANTIFUNGAL ACTIVITY OF Cymbopogon nardus (L. Rendle (CITRONELLA AGAINST Microsporum canis FROM ANIMALS AND HOME ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Isis Regina Grenier CAPOCI

    2015-12-01

    Full Text Available Dermatophytosis is a common zoonosis in urban centers. Dogs and cats have played an important role as its disseminators. Environmental decontamination is essential for the prevention of its propagation to humans and animals. However, sanitizers or disinfectants with antifungal activity, currently available, have high toxicity. The present study evaluated the in vitro effects of an extract of citronella (Cymbopogon nardus on 31 Microsporum canis isolates from animals and home environments. Susceptibility tests were performed based on document M38-A2 (2008 of the Clinical and Laboratory Standards Institute with modifications for natural products. Although susceptibility variation was observed between the fungus tested, the concentrations that inhibited the growth of 50 and 90% of the microorganisms were low (19.5 and 78 µg/mL, respectively. Thus, this citronella extract showed potent fungistatic and fungicide activities against M. canis isolated from animals and home environments. Therefore, it could be an alternative for dermatophytosis prophylaxis in the home environment.

  8. Phytostabilisation potential of lemon grass (Cymbopogon flexuosus (Nees ex Stend) Wats) on iron ore tailings.

    Science.gov (United States)

    Mohanty, M; Dhal, N K; Patra, P; Das, B; Reddy, P S R

    2012-01-01

    The present pot culture study was carried out for the potential phytostabilisation of iron ore tailings using lemon grass (Cymbopogon flexuosus) a drought tolerant, perennial, aromatic grass. Experiments have been conducted by varying the composition of garden soil (control) with iron ore tailings. The various parameters, viz. growth of plants, number of tillers, biomass and oil content of lemon grass are evaluated. The studies have indicated that growth parameters of lemon grass in 1:1 composition of garden soil and iron ore tailings are significantly more (-5% increase) compared to plants grown in control soil. However, the oil content of lemon grass in both the cases more or less remained same. The results also infer that at higher proportion of tailings the yield of biomass decreases. The studies indicate that lemongrass with its fibrous root system is proved to be an efficient soil binder by preventing soil erosion.

  9. High voltage dc cables

    Energy Technology Data Exchange (ETDEWEB)

    Bjustrom, B

    1965-12-01

    How stress distribution in dc cables varies with temperature and stress level, influence of polarity reversals and space charges, and different types of overvoltage to which dc cable may be subjected are discussed. Design problems, especially as related to corrosion protection and to mechanical stress caused by wire armoring during manufacturing and laying, accessories and work done on test methods, and the possibility of designing 400 to 600 kV dc cables for transmitting 2000 to 4000 MW are described.

  10. Family of multiport bidirectional DC-DC converters

    NARCIS (Netherlands)

    Tao, H.; Kotsopoulos, A.; Duarte, J.L.; Hendrix, M.A.M.

    2006-01-01

    Multiport DC-DC converters are of potential interest in applications such as generation systems utilising multiple sustainable energy sources. A family of multiport bidirectional DC-DC converters derived from a general topology is presented. The topology shows a combination of DC-link and magnetic

  11. Programmable dc motor controller

    Science.gov (United States)

    Hopwood, J. E.

    1982-11-01

    A portable programmable dc motor controller, with features not available on commercial instruments was developed for controlling fixtures during welding processes. The controller can be used to drive any dc motor having tachometer feedback and motor requirements not exceeding 30 volts, 3 amperes. Among the controller's features are delayed start time, upslope time, speed, and downslope time.

  12. Multilevel DC link inverter

    Science.gov (United States)

    Su, Gui-Jia

    2003-06-10

    A multilevel DC link inverter and method for improving torque response and current regulation in permanent magnet motors and switched reluctance motors having a low inductance includes a plurality of voltage controlled cells connected in series for applying a resulting dc voltage comprised of one or more incremental dc voltages. The cells are provided with switches for increasing the resulting applied dc voltage as speed and back EMF increase, while limiting the voltage that is applied to the commutation switches to perform PWM or dc voltage stepping functions, so as to limit current ripple in the stator windings below an acceptable level, typically 5%. Several embodiments are disclosed including inverters using IGBT's, inverters using thyristors. All of the inverters are operable in both motoring and regenerating modes.

  13. Bidirectional dc-to-dc Power Converter

    Science.gov (United States)

    Griesbach, C. R.

    1986-01-01

    Solid-state, series-resonant converter uses high-voltage thyristors. Converter used either to convert high-voltage, low-current dc power to lowvoltage, high current power or reverse. Taking advantage of newly-available high-voltage thyristors to provide better reliability and efficiency than traditional converters that use vacuum tubes as power switches. New converter essentially maintenance free and provides greatly increased mean time between failures. Attractive in industrial applications whether or not bidirectional capability is required.

  14. Efek antibakteri dan penghambatan biofilm ekstrak sereh (Cymbopogon nardus L. terhadap bakteri Streptococcus mutans

    Directory of Open Access Journals (Sweden)

    Zwista Yulia Dewi

    2015-12-01

    Antibacterial effect and biofilm inhibition Of Lemongrass extract (Cymbopogon nardus L. against the growth of Streptococcus mutans. Caries prevention can be carried out by several methods. One of them is by controlling the plaque accumulation on the surface of the teeth. Lemongrass (Cymbopogon nardus L is containing certain compound that can inhibit the growth of bacteria and biofilm. The objective of this research is to observe the influence of antibacterial and biofilm inhibition of lemongrass extract against the growth of S. mutans. Subjects were S. mutans bacteria on KHM90 test as much as 6x108 CFU/ml and on biofilm inhibition test as much as 15x108 CFU/ml. Lemongrass was extracted using petroleum ether followed by using 70% ethanol. Antibacterial activity test carried out with KHM90 determination test using microdilution method on microplate flat bottom 96 wells. Bacteria were prepared by making a suspension in NB media and adjusted to McFarland II standard (6x108 CFU/ml. Biofilm inhibition activity test was performed using microdilution method of the biofilm formed on microplate flat flexible PVC U-bottom 96 wells which were stained using 1% of crystal violet. Bacteria were prepared by making a suspension in BHI media and adjusted to McFarland V standard (15 x108 CFU/ml. The result in the form of optical density (OD was read by Bio-rad microplate reader Benchmark at a wavelength of 595 nm. The value of IC50 was determined by probit method using SPSS version 15.The results of this study of measurements on KHM90 test showed that 108,36% w/v is capable of inhibiting the growth of bacteria. Biofilm inhibitory activity showed IC50 lemongrass value was 0,137% w/v. The conclusion of this study is that lemongrass extract has antibacterial effect against bacteria S. mutans showed by KHM90 obtained at concentrations of 0,18% w/v and there is lemongrass extract biofilm inhibitory effect against the bacteria S. mutans indicated by IC50 value 0,137%

  15. A DC Transformer

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of the project was to demonstrate a true direct current (DC) transformer, a new electro-mechanical component with potentially high power applications; in...

  16. Three new DC-to-DC Single-Switch Converters

    Directory of Open Access Journals (Sweden)

    Barry W. Williams

    2017-06-01

    Full Text Available This paper presents a new family of three previously unidentified dc-to-dc converters, buck, boost, and buck-boost voltage-transfer-function topologies, which offer advantageous transformer coupling features and low capacitor dc voltage stressing. The three single-switch, single-diode, converters offer the same features as basic dc-to-dc converters, such as the buck function with continuous output current and the boost function with continuous input current. Converter time-domain simulations and experimental results (including transformer coupling support and extol the dc-to-dc converter concepts and analysis presented.

  17. Influence of season, harvest time and drying on Java citronella (Cymbopogon winterianus Jowitt volatile oil

    Directory of Open Access Journals (Sweden)

    Arie F. Blank

    Full Text Available Java citronella (Cymbopogon winterianus Jowitt is member of the Poaceae family. Java citronella volatile oil has been reported to be among the volatile oils, showing repellent, antimycotic, and acaricide activities. It has been known that agronomical factors have a great effect on both the quality and quantity of essential metabolites. For this reason, it is necessary to determine optimum levels of agronomical factors affecting plant growth and production. Harvest time and drying are very important agronomical factors. This study has been conducted in the Research farm of the " Universidade Federal de Sergipe" , Agronomical Engineering Department along 2002-2003 on the base of factorial experiment in randomized complete block design with three replications. Java citronella was cultivated in a 60 x 60 cm space. Early, midday, and late harvest at 9:00 h, 12:00 h, and 15:00 h were conducted on four different seasons. Fresh and dried leaves were used on the experiments. In order to study the effects of harvest time and drying, yields of dry and fresh herbage (kg/ha, moisture content (%, volatile oil content (% and yield (L/ha, and chemical composition of the volatile oil were measured. Seasonal changes had significant effect on yield of fresh herbage, yield and volatile oil content. Maximum volatile oil yields were observed at 9:00 during summer, winter, and spring. Volatile oil content was influenced by season and drying, but not influenced by harvest time.

  18. PERBANDINGAN KANDUNGAN MINYAK ATSIRI TANAMAN SEREH WANGI (Cymbopogon nardus L. Rendle YANG DITANAM DI LOKASI BERBEDA

    Directory of Open Access Journals (Sweden)

    Margareta Dacosta

    2017-03-01

    Full Text Available It has been conducted a research that aims to determine the ratio of essential oil content of citronella stalks (Cymbopogon nardus Rendle L. grown in the lowlands of Denpasar and the highlands of Bedugul. The experiment was conducted by using experimental designs. The parameters measured were the volume and the level of citronella oil produced. The sample preparation of powdered citronella stalks was as much as 200 grams, macerated with 96% ethanol and evaporated with Vacuum rotary evaporator to form condensed extract. The research used quantitative methods. The volume of hydro distillation was to obtain a crude extract of citronella stalks and the identification of active compounds was conducted by using Gas Chromatography / Mass Spectrometry (GC-MS. It can be concluded that the levels of citronella essential oil stalks from the highland of Bedugul was higher than the lowland areas of Denpasar, while the quality of essential oil of the lowland of Denpasar was better than that of the Bedugul highland. The content of secondary metabolites of the results of GC-MS analysis obtained from the essential oils contained in the analyzed crude extract of citronella stalks namely the compound of Selina-6-en-4-ol (2287322, the compound of n-hexadecanoic acid (1238019 and the compound of Driman-8,11-diol from the lowland of Denpasar while the Selina compound-6-en-4-ol (1856137 from the highland of Bedugul. Keywords: Citronella, essential oil content, altitude

  19. Optimal Extraction and Evaluation on the Oil Content of Citronella Oil Extracted From Cymbopogon Nardus

    International Nuclear Information System (INIS)

    Weng, D.C.J.; Jalifah Latip; Siti Aishah Hasbullah; Sastrohamidjojo, H.

    2015-01-01

    An investigation on the extraction of citronella oil from Cymbopogon nardus (C. nardus) using a custom made medium scale steam distillation apparatus has been conducted. The Clevenger apparatus was used to generate a continuous flow of the hydrosol, creating an efficient distillation system. In the case for C. nardus leave samples orientation; the sleeping/ standing and close/ loose packing in steam distillator was found to have significant effects on the yield of extraction. The 3.5 hours distillation process produced an extraction yield of 0.64 % in sleeping position of the leaves as compared to the standing position (0.43 %), while the loose packing (0.70 %) has almost two fold of yield percentage as compared to the close-packing (0.40 %) of the leaves. Therefore, the steam distillation of C. nardus leaves using a custom made medium scale steam distillation apparatus was found to be most effective in the combination of sleeping position with a loose packing. Furthermore, the age of C. nardus leaves also affect the physical and chemical quality of the citronella oil extracted. The younger leaves produced citronella oil that consists mainly of citronellal, citronellol and geraniol while the older leaves contained a high composition of citral. (author)

  20. Ethanol extract of Cymbopogon winterianus on mortality and number of eggs of Tetranychus urticae

    Directory of Open Access Journals (Sweden)

    Victor Bernardo Vicentini

    2015-07-01

    Full Text Available Plant extracts have been studied as a promising source of natural insecticides. This study assessed the effect of the ethanol extract of Cymbopogon winterianus Jowitt (citronella grass in comparison with an insecticide containing azadirachtin (ICA on mortality and number of eggs of Tetranychus urticae Koch (Acari: Tetranychidae in laboratory conditions. For the tests, the mites were sprayed with the aid of a Potter spray tower. To assess the mortality of females, LC50 value for extract of citronella grass and ICA was, respectively, 2.63 and 2.83%. With respect to the number of eggs, the greatest reduction was observed at a concentration of 5% for the evaluation period of 120h, both for the extract of citronella grass (86% and for ICA (81%. These results suggest the potential of the ethanol extract of citronella grass to control of T. urticae. However, experiments, under field conditions, involving other populations of T. urticae should be performed to verify the efficacy of this extract as an alternative to be used in pest management programs

  1. Essential oil from Cymbopogon flexuosus as the potential inhibitor for HSP90.

    Science.gov (United States)

    Gaonkar, Roopa; Shiralgi, Yallappa; Lakkappa, Dhananjaya B; Hegde, Gurumurthy

    2018-01-01

    The essential oil of Cymbopogon flexuosus or lemongrass oil (LO) is reported to have antibacterial, antifungal and anticancerous effects. HSP90 is one of the major chaperones responsible for the proper folding of cancer proteins. In this paper we show that the essential oil of C. flexuosus significantly suppresses the HSP90 gene expression. The cytotoxicity of the compounds was tested by MTT assay and the gene expression studies were carried out using HEK-293 and MCF-7 cells. Also we tested the efficacy of the major component of this essential oil viz. citral and geraniol in inhibiting the HSP90 expression. The oil was found to be more cytotoxic to MCF-7 cells with different IC 50 values for the oil (69.33 μg/mL), citral (140.7 μg/mL) and geraniol (117 μg/mL). The fold change of expression was calculated by RT-qPCR using ΔΔCt (2 ^-ΔΔCt ) method and it was 0.1 and 0.03 in MCF-7 cells at 80 μg/mL and 160 μg/mL of LO. Western blot results showed suppression of HSP90 protein expression and HSP90 - ATPase activity inhibition was also observed using LO. This study shows the anticancer mechanism exhibited by the essential oil of C. flexuosus is by the inhibition of the important chaperone protein HSP90.

  2. Attraction behaviour of Anagrus nilaparvatae to remote lemongrass (Cymbopogon distans) oil and its volatile compounds.

    Science.gov (United States)

    Mao, Guo-Feng; Mo, Xiao-Chang; Fouad, Hatem; Abbas, Ghulam; Mo, Jian-Chu

    2018-03-01

    Utilisation of Anagrus nilaparvatae is a promising and effective method for planthoppers manipulation. Twenty-seven components of remote lemongrass (Cymbopogon distans) oil were identified by GC/MS and nine volatiles were selected for behavioural experiments. In this study, we noted that the remote lemongrass oil was attractive to female A. nilaparvatae at concentrations of 0.1 and 1 mg/L. α-Pinene, β-pinene, eucalyptol, carveol and D-carvone attracted female wasps in the dose-dependent bioassays. Blend 1 (a mixture of eucalyptol, D-carvone, carveol, α-pinene, and β-pinene with ratios of remote lemongrass oil volatiles of 625:80:11:5:3) attracted female wasps at 10 mg/L, while blend 2 (a mixture of the same five volatiles at the same loading ratio) attracted them at 0.1 and 1 mg/L. These results suggested that plant essential oils could be attractants for natural enemies to control pests. The ratios of volatiles in the mixtures affect the attractiveness of the synthetic mixtures.

  3. A Study on Antimicrobial Activities of Essential Oils of Different Cultivars of Lemongrass (Cymbopogon flexuosus

    Directory of Open Access Journals (Sweden)

    Ashish Kumar Gupta, Ritam Muhury, Deepak Ganjewala

    2016-10-01

    Full Text Available Background: Cymbopogon flexuosus popularly known as lemongrass provides a lemon scented essential oil which is widely used in flavour and fragrance, perfumery, food and pharmaceuticals. The aim of the present study was to assess antimicrobial activities of essential oils of three lemongrass cultivars viz., Pragati, Praman and Suvarna. Methods: Essential oils were isolated from one month old plants by hydro-distillation in mini Clevenger apparatus for 2 h. Antimicrobial activities were determined by agar well diffusion method Results: Lemongrass oils exhibited strong antimicrobial activity against all the microbes except E coli. Mean inhibition zone diameter (mm against bacteria was ranged 27-38 mm. B. Subtilis was the most sensitive bacterium to all essential oils. Essential oils also showed strong antifungal effects against both A. niger and C. albicans with mean inhibition zone diameter (mm values 20-26 and 27-29 mm, respectively. Statistical analyses revealed that antimicrobial activity shown by essential oils were significant (p > 0.05. Conclusion: The study revealed strong antimicrobial potential of the essential oil against pathogenic microbial strains which may be of high clinical importance in future.

  4. Three-port DC-DC converter with new integrated transformer for DC Distribution Systems

    DEFF Research Database (Denmark)

    Ouyang, Ziwei; Andersen, Michael A. E.

    2014-01-01

    A new integrated transformer for three-port dc-dc converter is proposed to overcome the power coupling effect existed in some known multiple inputs dc-dc converters. Orthogonal primary windings arrangement and in series connection of diagonal secondary Windings enables a fully power decoupling...

  5. 75 FR 23571 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

    Science.gov (United States)

    2010-05-04

    ... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10... amends Sec. 39.13 by adding the following new AD: 2010-09-12 McDonnell Douglas Corporation: Amendment 39... to McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10-30F (KC-10A...

  6. Design and Testing of Boost Type DC/DC Converter for DC Motor Control Applications

    OpenAIRE

    Samman, Faizal Arya; Akil, Yusri Syam; Noor, Nirwan A.

    2017-01-01

    in The Proceeding of The 2nd International Symposium on Smart Material and Mechatronics 2015 This paper presents the design and testing of a boost type DC/DC converter circuit, which can be used for DC motor control applications. The Boost converter is designed using DC chopper and DC chopper cascade configurations. The experimental setup was made by connecting the boost converter circuit with four types of DC motor, i.e. self-excited DC motor shunt, series, compound and separately exci...

  7. Control of improved full-bridge three-level DC/DC converter for wind turbines in a DC grid

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2013-01-01

    transformer in the IFBTL dc/dc converter. A modulation strategy, including two operation modes, is proposed for the IFBTL dc/dc converter. Then, a voltage balancing control strategy is proposed for the IFBTL dc/dc converter. Furthermore, the control of the wind turbine based on the IFBTL dc/dc converter......This paper presents an improved full-bridge three-level (IFBTL) dc/dc converter for a wind turbine in a dc grid by inserting a passive filter into the dc/dc converter to improve the performance of the converter. The passive filter can effectively reduce the voltage stress of the medium frequency...

  8. Chemical composition, antioxidant and antimicrobial activity of the essential oil and methanol extract of the Egyptian lemongrass Cymbopogon proximus Stapf

    Energy Technology Data Exchange (ETDEWEB)

    Selim, S.A.

    2011-07-01

    The present study was conducted to evaluate the in vitro antimicrobial and antioxidant properties of the essential oil (Eo) and methanol extract from a unique, Egyptian endemic plant, Cymbopogon proximus STAPF. The chemical composition of a hydrodistilled Eo of C. proximus was analyzed by a GC and GC/MS system. A total of 19 constituents representing 95.47% of the oil were identified: piperitone (72.44%), elemol (9.43%), a - eudesmol (4.34%), limonene (2.45%) and a - eudesmol. (Author).

  9. Overview of Multi-DC-Bus Solutions for DC Microgrids

    DEFF Research Database (Denmark)

    Ricchiuto, D.; Mastromauro, R.A.; Liserre, Marco

    2013-01-01

    DC Microgrids have recently received a lot of attention in the last years due to high penetration of renewable energy sources as well as distributed energy storage systems. In the future DC microgrids could be preferable respect to AC microgrids in terms of redundancy since multi-DC-Bus solutions...... could provide a continuative power supply to the loads. An overview of Multi-DC-Bus solutions is presented in this paper. The performances are compared on the basis of possible DC microgrid configurations, redundancy, different DC voltage levels....

  10. Proline accumulation in lemongrass (Cymbopogon flexuosus Stapf.) due to heavy metal stress.

    Science.gov (United States)

    Handique, G K; Handique, A K

    2009-03-01

    Toxic heavy metals viz. lead, mercury and cadmium induced differential accumulation of proline in lemongrass (Cymbopogon flexuosus Stapf.) grown in soil amended with 50, 100, 200, 350 and 500 mg kg(-1) of the metals have been studied. Proline accumulation was found to be metal specific, organ specific and linear dose dependant. Further, proline accumulation following short term exposure (two months after transplantation) was higher than long term exposure (nine months after transplantation). Proline accumulation following short term exposure was 2.032 to 3.839 micro moles g(-1) for cadmium (50-200 mg kg(-1)); the corresponding range for mercury was 1.968 to 5.670 micro moles g(-1) and 0.830 to 4.567 micro moles g(-1) for lead (50-500 mg kg(-1) for mercury and lead). Proline accumulation was consistently higher in young tender leaf than old leaf, irrespective of the metal or duration of exposure. For cadmium treatment proline level was 2.032 to 3.839 micro moles g(-1) for young leaves while the corresponding value for old leaf was 1.728 to 2.396 micro moles g(-1) following short term exposure. The same trend was observed for the other two metals and duration of exposure. For control set proline accumulation in root was 0.425 micro moles g(-1) as against 0.805 and 0.533 micro moles g(-1) in young and old leaves respectively indicating that proline accumulation in root are lower than leaves, under both normal and stressed condition.

  11. Evaluación de la toxicidad aguda de extractos de plantas medicinales por un método alternativo (Evaluation of acute toxicity of extracts of medicinal plants by an alternative testing)

    OpenAIRE

    Deodelsy Bermúdez Toledo:; |Emilio Monteagudo Jimenez; Maria Boffill Cárdenas; Luis E. Díaz Costa; Alexander Roca Simeón; Emoe Betancourt Morgado; Enrique A Silveira Prado

    2007-01-01

    Se evaluó la toxicidad a dosis única de seis extractos de plantas medicinales: Psidium guajava L. (guayaba), Eucalyptus citriodoraHooker (eucalipto de limón), Cymbopogon citratus (DC) Stapf (caña santa, hierba de limón), Hibiscus elatus Sw. (majagua), Justicia pectoralis Jacq. (tilo), Plectranthus amboinicus (Lour.) Spreng (orégano francés) mediante un método alternativo e internacionalmente validado y aceptado (procedimiento de dosis fijas) en ratasSprague Dawley. El grupo tratado recibió po...

  12. Multi Bus DC-DC Converter in Electric Hybrid Vehicles

    Science.gov (United States)

    Krithika, V.; Subramaniam, C.; Sridharan, R.; Geetha, A.

    2018-04-01

    This paper is cotncerned with the design, simulation and fabrication of the prototype of a Multi bus DC- DC converter operating from 42V DC and delivering 14V DC and 260V DC. As a result, three DC buses are interconnected through a single power electronic circuitry. Such a requirement is energized in the development of a hybrid electric automobile which uses the technology of fuel cell. This is implemented by using a Bidirectional DC-DC converter configuration which is ideally suitable for multiple outputs with mutual electrical isolation. For the sake of reduced size and cost of step-up transformer, selection of a high frequency switching cycle at 10 KHz was done.

  13. dc Arc Fault Effect on Hybrid ac/dc Microgrid

    Science.gov (United States)

    Fatima, Zahra

    The advent of distributed energy resources (DER) and reliability and stability problems of the conventional grid system has given rise to the wide spread deployment of microgrids. Microgrids provide many advantages by incorporating renewable energy sources and increasing the reliability of the grid by isolating from the main grid in case of an outage. AC microgrids have been installed all over the world, but dc microgrids have been gaining interest due to the advantages they provide over ac microgrids. However the entire power network backbone is still ac and dc microgrids require expensive converters to connect to the ac power network. As a result hybrid ac/dc microgrids are gaining more attention as it combines the advantages of both ac and dc microgrids such as direct integration of ac and dc systems with minimum number of conversions which increases the efficiency by reducing energy losses. Although dc electric systems offer many advantages such as no synchronization and no reactive power, successful implementation of dc systems requires appropriate protection strategies. One unique protection challenge brought by the dc systems is dc arc faults. A dc arc fault is generated when there is a gap in the conductor due to insulation degradation and current is used to bridge the gap, resulting in an arc with very high temperature. Such a fault if it goes undetected and is not extinguished can cause damage to the entire system and cause fires. The purpose of the research is to study the effect of the dc arc fault at different locations in the hybrid ac/dc microgrid and provide insight on the reliability of the grid components when it is impacted by arc faults at various locations in the grid. The impact of dc arc fault at different locations on the performance of the PV array, wind generation, and constant power loads (CPL) interfaced with dc/dc converters is studied. MATLAB/Simulink is used to model the hybrid ac/dc microgrid and arc fault.

  14. Early Oscillation Detection for DC/DC Converter Fault Diagnosis

    Science.gov (United States)

    Wang, Bright L.

    2011-01-01

    The electrical power system of a spacecraft plays a very critical role for space mission success. Such a modern power system may contain numerous hybrid DC/DC converters both inside the power system electronics (PSE) units and onboard most of the flight electronics modules. One of the faulty conditions for DC/DC converter that poses serious threats to mission safety is the random occurrence of oscillation related to inherent instability characteristics of the DC/DC converters and design deficiency of the power systems. To ensure the highest reliability of the power system, oscillations in any form shall be promptly detected during part level testing, system integration tests, flight health monitoring, and on-board fault diagnosis. The popular gain/phase margin analysis method is capable of predicting stability levels of DC/DC converters, but it is limited only to verification of designs and to part-level testing on some of the models. This method has to inject noise signals into the control loop circuitry as required, thus, interrupts the DC/DC converter's normal operation and increases risks of degrading and damaging the flight unit. A novel technique to detect oscillations at early stage for flight hybrid DC/DC converters was developed.

  15. Thyristors for dc transmission

    Energy Technology Data Exchange (ETDEWEB)

    1966-05-06

    As a first stage towards determining the feasibility of applying thyristors to hvdc converter terminals, the Westinghouse Electric Corporation has built a converter laboratory capable of testing thyristors under conditions similar to those which would have to be met in a 200 kV dc system. The equipment has been designed to test a 5 kV 600 A group of thyrisotrs, elevated 200 kV above earth. This rating has been chosen so that there would be a sufficient number of thyristors in series to enable the gating and voltage division characteristics to be investigated and at the same time the group could be operated at a potential equivalent to a complete 200 kV dc bridge.

  16. TOPOLOGICAL REVIEW AND ANALYSIS OF DC-DC BOOST CONVERTERS

    Directory of Open Access Journals (Sweden)

    V. INDRA GANDHI

    2017-06-01

    Full Text Available DC voltage boost up is essential in numerous applications; especially considering Photovoltaic (PV based renewable power generation system. The conventional DC-DC boost converter is the most admired configuration for this scheme, even if the converter efficiency is restricted at duty cycle near to maximum value. In order to find solution to the problem and improve its conversion capability, many converter configurations have been implemented so far. With this circumstance, this research work proposes to give overview of a few most imperative research works related to DC-DC boost converters. Some configurations are covered and classified basically based on the application. The major benefits and disadvantages related to the available techniques are also briefly conveyed. At last, a proper evaluation is recognized among the important types of DC-DC boost converters in terms of efficiency, number of components, and stability.

  17. An Integrated Multifunctional Bidirectional AC/DC and DC/DC Converter for Electric Vehicles Applications

    OpenAIRE

    Liwen Pan; Chengning Zhang

    2016-01-01

    This paper presents an on-board vehicular battery charger that integrates bidirectional AC/DC converter and DC/DC converter to achieve high power density for application in electric vehicles (EVs). The integrated charger is able to transfer electrical energy between the battery pack and the electric traction system and to function as an AC/DC battery charger. The integrated charger topology is presented and the design of passive components is discussed. The control schemes are developed for m...

  18. On and off controlled resonant dc-dc power converter

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a resonant DC-DC power converter comprising an input side circuit comprising a positive and a negative input terminal for receipt of an input voltage or current and an output side circuit comprising positive and negative output terminals for supply of a converter...... output voltage and connection to a converter load. The resonant DC-DC power converter further comprises a rectification circuit connected between an output of a resonant network and the output side circuit. The resonant network is configured for alternatingly being charged from the input voltage...... or current and discharged through the rectification circuit by a first controllable switch arrangement in accordance with a first switch control signal. A second controllable switch arrangement of the resonant DC-DC power converter is configured to select a first impedance characteristic of the resonant...

  19. DC Cable for Railway

    Science.gov (United States)

    Tomita, Masaru

    The development of a superconducting cable for railways has commenced, assuming that a DC transmission cable will be used for electric trains. The cable has been fabricated based on the results of current testing of a superconducting wire, and various evaluation tests have been performed to determine the characteristics of the cable. A superconducting transmission cable having zero electrical resistance and suitable for railway use is expected to enhance regeneration efficiency, reduce power losses, achieve load leveling and integration of sub-stations, and reduce rail potential.

  20. Auxiliary resonant DC tank converter

    Science.gov (United States)

    Peng, Fang Z.

    2000-01-01

    An auxiliary resonant dc tank (ARDCT) converter is provided for achieving soft-switching in a power converter. An ARDCT circuit is coupled directly across a dc bus to the inverter to generate a resonant dc bus voltage, including upper and lower resonant capacitors connected in series as a resonant leg, first and second dc tank capacitors connected in series as a tank leg, and an auxiliary resonant circuit comprising a series combination of a resonant inductor and a pair of auxiliary switching devices. The ARDCT circuit further includes first clamping means for holding the resonant dc bus voltage to the dc tank voltage of the tank leg, and second clamping means for clamping the resonant dc bus voltage to zero during a resonant period. The ARDCT circuit resonantly brings the dc bus voltage to zero in order to provide a zero-voltage switching opportunity for the inverter, then quickly rebounds the dc bus voltage back to the dc tank voltage after the inverter changes state. The auxiliary switching devices are turned on and off under zero-current conditions. The ARDCT circuit only absorbs ripples of the inverter dc bus current, thus having less current stress. In addition, since the ARDCT circuit is coupled in parallel with the dc power supply and the inverter for merely assisting soft-switching of the inverter without participating in real dc power transmission and power conversion, malfunction and failure of the tank circuit will not affect the functional operation of the inverter; thus a highly reliable converter system is expected.

  1. PENGGUNAAN FUZZY LOGIC UNTUK KONTROL PARALLEL CONVERTER DC-DC

    Directory of Open Access Journals (Sweden)

    Bambang Prio Hartono

    2012-09-01

    Full Text Available Abstract: Using system fuzzy logic as control  technology have been used on low load dc-dc converter with combined parallel compiled  dc-dc converter can  obtain big load.   With existence of differrence of component parameter and each parallel compiled converter can obtained different current  and voltage output.  Function of controller  for to do adjustment, so that current which is applied  to  load by each converter  can be obtained  difference error as small as possible or same. The object of research is developing design of large signal dc-dc converter which is  combined with using  FLC so that  obtain  better performance.  To get better performance have been made plant model and simulation with CDE method.  The more systematic  system and design is needed to overcome bigger load  on dc-dc converter, so that parallel  compiled current master slave control system on dc-dc converter with using fuzzy logic  controller is used. Result of  research showed that error or difference of  current  which is applied to load can handled by fuzzy logic  controller.  Technic of current and voltage controller co to do adjustment current and voltage distribution  equally to load.  Distribution of iL1,iL2 and  output voltage Vo on dc-dc  converter with load 2,25 until  7,875 and voltage  100  until 120 volt,  load current beetwen  12 until 48, % relatif  error  Vo  0,4% until  0,9%.

  2. Step-Up DC-DC Power Converter

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a step-up DC-DC power converter which comprises a primary side circuit and a secondary side circuit coupled through a galvanic isolation barrier. The primary side circuit comprises a positive and a negative input terminal for receipt of an input voltage and an input...... being charged from the input voltage and discharged to the output capacitor through the galvanic isolation barrier in accordance with a switch control signal to produce the converter output voltage. The step-up DC-DC power converter comprises an electrical short-circuit connection across the galvanic...

  3. DC Distribution Systems and Microgrids

    DEFF Research Database (Denmark)

    Dragicevic, Tomislav; Anvari-Moghaddam, Amjad; Quintero, Juan Carlos Vasquez

    2017-01-01

    summarized. Due to its attractive characteristics in terms of compliance with modern generation, storage and electronic load technologies, high reliability and current carrying capacity, as well as simple control, DC systems are already an indispensable part of power systems. Moreover, the existing......A qualitative overview of different hardware topologies and control systems for DC MGs has been presented in this chapter. Some challenges and design considerations of DC protections systems have also been discussed. Finally, applications of DC MGs in emerging smart grid applications have been...... challenges such as protection issues will be effectively resolved in the near future due to fast progress of semiconductor technology which is a key enabler cheap and reliable future DC solid-state protection systems. Therefore, it is the view of the author that more and more DC systems will appear...

  4. Very High Frequency Half Bridge DC/DC Converter

    DEFF Research Database (Denmark)

    Madsen, Mickey Pierre; Knott, Arnold; Andersen, Michael A. E.

    2014-01-01

    This paper presents the first, off chip, class DE (resonant half bridge) converter working in the Very High Frequency (VHF) range. The benefits of using half bridge circuits both in the inverter and rectifier part of a VHF resonant dc/dc converter are analyzed and design equations for all...

  5. SCM Handbooks for dc-to-dc Converters

    Science.gov (United States)

    Lee, F.; Mohmoud, M.; Yu, Y.

    1984-01-01

    Two documents aid in design of control modules for dc-to-dc converters. Features of SCM include: Adaptive stability, power component stress limiting, implementation of various control laws, unified design approach. Analysis and quidelines contained in handbooks enable engineer to design SCM circuit and confidently predict resulting overall performance.

  6. Sheppard-Taylor Isolated High Boost DC-DC Converter

    DEFF Research Database (Denmark)

    Chub, Andrii; Siwakoti, Yam Prasad; Vinnikov, Dmitri

    2017-01-01

    This paper presents a new galvanically isolated step-up dc-dc converter intended for low-power but high step-up applications. The proposed converter is capable of regulating output voltage within a wide range of the input voltage or load variations. In contrast to competitors, the converter can...

  7. Dc-To-Dc Converter Uses Reverse Conduction Of MOSFET's

    Science.gov (United States)

    Gruber, Robert P.; Gott, Robert W.

    1991-01-01

    In modified high-power, phase-controlled, full-bridge, pulse-width-modulated dc-to-dc converters, switching devices power metal oxide/semiconductor field-effect transistors (MOSFET's). Decreases dissipation of power during switching by eliminating approximately 0.7-V forward voltage drop in anti-parallel diodes. Energy-conversion efficiency increased.

  8. A Current-Fed Isolated Bidirectional DC-DC Converter

    DEFF Research Database (Denmark)

    Sun, Xiaofeng; Wu, Xiaoying; Shen, Yanfeng

    2017-01-01

    This paper proposes a current-fed isolated bidirectional DC-DC converter (CF-IBDC) which has the advantages of wide input voltage range, low input current ripple, low conduction losses, and soft switching over the full operating range. Compared with conventional CF-IBDCs, the voltage spikes...

  9. Power flow analysis for DC voltage droop controlled DC microgrids

    DEFF Research Database (Denmark)

    Li, Chendan; Chaudhary, Sanjay; Dragicevic, Tomislav

    2014-01-01

    This paper proposes a new algorithm for power flow analysis in droop controlled DC microgrids. By considering the droop control in the power flow analysis for the DC microgrid, when compared with traditional methods, more accurate analysis results can be obtained. The algorithm verification is ca...

  10. A DC Transformer

    Science.gov (United States)

    Youngquist, Robert C.; Ihlefeld, Curtis M.; Starr, Stanley O.

    2013-01-01

    A component level dc transformer is described in which no alternating currents or voltages are present. It operates by combining features of a homopolar motor and a homopolar generator, both de devices, such that the output voltage of a de power supply can be stepped up (or down) with a corresponding step down (or up) in current. The basic theory for this device is developed, performance predictions are made, and the results from a small prototype are presented. Based on demonstrated technology in the literature, this de transformer should be scalable to low megawatt levels, but it is more suited to high current than high voltage applications. Significant development would be required before it could achieve the kilovolt levels needed for de power transmission.

  11. Olonisakin et al (15)

    African Journals Online (AJOL)

    DELL

    The chemical composition of the essential oil extracted by hydro-distillation using Clevenger apparatus from ... Toxicity of the essential oils using anti-feedant and filter paper ..... and biological activity of Cymbopogon citratus from Keffi, Nigeria.

  12. Evaluation of Botanical Herbicides against Common Weed Species ...

    African Journals Online (AJOL)

    test the inhibitory potential of essential oils extracted from eight locally available plants and .... from C. citratus was in different as weed growth observed with standard ..... NB:-Con = Control, EC = Eucalyptus citrodora, CW = Cymbopogon ...

  13. Regeneration from embryogenic callus and suspension cultures of ...

    African Journals Online (AJOL)

    ehab

    2012-04-25

    Apr 25, 2012 ... cultures of the wild medicinal plant Cymbopogon schoenanthus ... nardus, C. martini, C. citratus and C. flexuosus are the source of palmerosa, citronella, lemon-grass and oil of. Malabar ...... marketing of essential oils. J. Med.

  14. Browse Title Index

    African Journals Online (AJOL)

    Items 701 - 750 of 1309 ... Vol 11, No 1 (2014), Exploration of nutraceutical potential of herbal oil formulated .... on essential oil composition of endemic Kundmannia anatolica Hub.-Mor ... Hepatoprotective Effect Of Cymbopogon Citratus Aqueous ...

  15. (Mycosphaerella fijiensis Morelet) chez le bananier plantain

    African Journals Online (AJOL)

    SARAH

    31 mars 2014 ... gratissimum and sprayed sprayed in a mixture with banole oil at 5 ml/l. The application of ..... Cymbopogon citratus à inhiber la croissance des appressoria de ... American Perfumer & Essential Oil Review,. 1928, 467-503.

  16. Browse Title Index

    African Journals Online (AJOL)

    Items 101 - 150 of 391 ... Vol 11, No 1 (2009), Efficacy of neem oil and neemazal against the larger ... monitoring in the management of essential hypertension, Abstract ... Moringa oleifera, Hibiscus sabdariffa and Cymbopogon citratus, Abstract.

  17. 'WARA' A WEST AFRICAN SOFT CHEESE

    African Journals Online (AJOL)

    Babalobi

    2011-12-07

    Dec 7, 2011 ... Cymbopogon citratus (Amazon Herbs, Wonglaan, 10, Paramaribo, Suriname). The .... provided an ideal environment for the microorganisms. ... reduce the risk of microbial spoilage of food and possibility of food poisoning.

  18. Effect of the purification of antidermatophytic proteins from Nigella ...

    African Journals Online (AJOL)

    The antidermatophytic activities of proteins which are extracted from four plant species (Carum carvi, Cymbopogon citratus, Moringa oleifera, and Nigella sativa) on four zoophilic dermatophytes (Microsporum canis, Microsporum equinum, Trichophyton mentagrophytes, and Trichophyton verrucosum) were evaluated in this ...

  19. The performance of the DC motor by the PID controlling PWM DC-DC boost converter

    OpenAIRE

    Can, Erol; Sayan, Hasan Hüseyin

    2017-01-01

    This paper presents the PID controlling direct current (DC) to the direct current boost converter feds DC motor which has a 3.68 kW and 240 V of DC voltage input on its characteristics. What is first formed is the boost converter mathematical model at the design stage. Secondly, a mathematical model of the DC motor is created so that the boost converter with the machine can be established and modeled at the Matlab Simulink. The PID controller is considered for arranging a pulse width modulati...

  20. Lemongrass and citral effect on cytokines production by murine macrophages.

    Science.gov (United States)

    Bachiega, Tatiana Fernanda; Sforcin, José Maurício

    2011-09-01

    Cymbopogon citratus (DC) Stapf (Poaceae-Gramineae), an herb commonly known as lemongrass (LG), is an important source of ethnomedicines as well as citral, the major constituent of Cymbopogon citratus, used in perfumery, cosmetic and pharmaceutical industries for controlling pathogens. Thus, the goal of this work was to analyze the effect of LG and citral on cytokines production (IL-1β, IL-6 and IL-10) in vitro, as well as before or after LPS incubation. Peritoneal macrophages from BALB/c mice were treated with LG or citral in different concentrations for 24h. The concentrations that inhibited cytokines production were tested before or after macrophages challenge with LPS, in order to evaluate a possible anti-inflammatory action. Supernatants of cell cultures were used for cytokines determination by ELISA. As to IL-1β, only citral inhibited its release, exerting an efficient action before LPS challenge. LG and citral inhibited IL-6 release. Cymbopogon citratus showed inhibitory effects only after LPS challenge, whereas citral prevented efficiently LPS effects before and after LPS addition. Citral inhibited IL-10 production and although LG did not inhibit its production, the concentration of 100 μg/well was tested in the LPS-challenge protocol, because it inhibited IL-6 production. LG inhibited LPS action after macrophages incubation with LPS, while citral counteracted LPS action when added before or after LPS incubation. LG exerted an anti-inflammatory action and citral may be involved in its inhibitory effects on cytokines production. We suggest that a possible mechanism involved in such results could be the inhibition of the transcription factor NF-κB. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  1. 75 FR 61989 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-8-31, DC-8-32, DC-8-33, DC-8-41...

    Science.gov (United States)

    2010-10-07

    ... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 8-31, DC-8-32, DC-8-33, DC-8-41, DC-8-42, and... to all of the McDonnell Douglas Corporation airplanes identified above. The existing AD currently... the following new airworthiness directive (AD): 2010-21-03 McDonnell Douglas Corporation: Amendment 39...

  2. Triple voltage dc-to-dc converter and method

    Science.gov (United States)

    Su, Gui-Jia

    2008-08-05

    A circuit and method of providing three dc voltage buses and transforming power between a low voltage dc converter and a high voltage dc converter, by coupling a primary dc power circuit and a secondary dc power circuit through an isolation transformer; providing the gating signals to power semiconductor switches in the primary and secondary circuits to control power flow between the primary and secondary circuits and by controlling a phase shift between the primary voltage and the secondary voltage. The primary dc power circuit and the secondary dc power circuit each further comprising at least two tank capacitances arranged in series as a tank leg, at least two resonant switching devices arranged in series with each other and arranged in parallel with the tank leg, and at least one voltage source arranged in parallel with the tank leg and the resonant switching devices, said resonant switching devices including power semiconductor switches that are operated by gating signals. Additional embodiments having a center-tapped battery on the low voltage side and a plurality of modules on both the low voltage side and the high voltage side are also disclosed for the purpose of reducing ripple current and for reducing the size of the components.

  3. Bi-Directional DC-DC Converter for PHEV Applications

    Energy Technology Data Exchange (ETDEWEB)

    Abas Goodarzi

    2011-01-31

    Plug-In Hybrid Electric Vehicles (PHEV) require high power density energy storage system (ESS) for hybrid operation and high energy density ESS for Electric Vehicle (EV) mode range. However, ESS technologies to maximize power density and energy density simultaneously are not commercially feasible. The use of bi-directional DC-DC converter allows use of multiple energy storage, and the flexible DC-link voltages can enhance the system efficiency and reduce component sizing. This will improve fuel consumption, increase the EV mode range, reduce the total weight, reduce battery initial and life cycle cost, and provide flexibility in system design.

  4. RESONANT STEP-DOWN DC-DC POWER CONVERTERS

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a resonant step-down DC-DC power converter which comprises a primary side circuit and a secondary side circuit coupled through a galvanic isolation barrier. The primary side circuit comprises a positive and a negative input terminal for receipt of an input voltage...... charged from the input voltage and discharged to the output capacitor through the galvanic isolation barrier by a semiconductor switch arrangement in accordance with a switch control signal to produce the converter output voltage. The resonant step-down DC-DC power converter comprises an electrical short......-circuit connection across the galvanic isolation barrier connecting, in a first case, the second negative electrode of the output capacitor to the positive input terminal of the primary side circuit or, in a second case, connecting the second positive electrode of the output capacitor to the negative input terminal...

  5. Decentralized Interleaving of Paralleled Dc-Dc Buck Converters: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Brian B [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Rodriguez, Miguel [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sinha, Mohit [University of Minnesota; Dhople, Sairaj [University of Minnesota; Poon, Jason [University of California at Berkeley

    2017-09-01

    We present a decentralized control strategy that yields switch interleaving among parallel connected dc-dc buck converters without communication. The proposed method is based on the digital implementation of the dynamics of a nonlinear oscillator circuit as the controller. Each controller is fully decentralized, i.e., it only requires the locally measured output current to synthesize the pulse width modulation (PWM) carrier waveform. By virtue of the intrinsic electrical coupling between converters, the nonlinear oscillator-based controllers converge to an interleaved state with uniform phase-spacing across PWM carriers. To the knowledge of the authors, this work represents the first fully decentralized strategy for switch interleaving of paralleled dc-dc buck converters.

  6. Active pre-filters for dc/dc Boost regulators

    Directory of Open Access Journals (Sweden)

    Carlos Andrés Ramos-Paja

    2014-05-01

    Full Text Available This paper proposes an active pre-filter to mitigate the current harmonics generated by classical dc/dc Boost regulators, which generate current ripples proportional to the duty cycle. Therefore, high output voltage conditions, i.e., high voltage conversion ratios, produce high current harmonics that must be filtered to avoid damage or source losses. Traditionally, these current components are filtered using electrolytic capacitors, which introduce reliability problems because of their high failure rate. The solution introduced in this paper instead uses a dc/dc converter based on the parallel connection of the Boost canonical cells to filter the current ripples generated by the Boost regulator, improving the system reliability. This solution provides the additional benefits of improving the overall efficiency and the voltage conversion ratio. Finally, the solution is validated with simulations and experimental results.

  7. Linking DC together with TRSL

    DEFF Research Database (Denmark)

    Haxthausen, Anne Elisabeth; Yong, X.

    2000-01-01

    in a method for real-time developments. An operational semantics with behavior is specified for TRSL. It is defined what its means for a TRSL process to satisfy a DC requirement, and a method for verifying whether the satisfaction relation holds or not is provided. Our contribution also demonstrates a general......Duration Calculus (DC) is an interval-based real-time logic, which can be used in capturing and eliciting users' real-time requirements. The Timed RAISE Specification Language (TRSL) is an extension of the RAISE Specification Language with real-time features. This paper links DC and TRSL together...

  8. DC Microgrids—Part II

    DEFF Research Database (Denmark)

    Dragicevic, Tomislav; Lu, Xiaonan; Quintero, Juan Carlos Vasquez

    2016-01-01

    distribution applications such as traction, telecom, vehicular and distributed power systems can be classified under DC MG framework and ongoing development and expansion of the field is largely influenced by concepts used over there. This paper aims firstly to shed light on the practical design aspects of DC...... MG technology concerning typical power hardware topologies and their suitability for different emerging smart grid applications. Then, an overview of the state of the art in DC MG protection and grounding is provided. Owing to the fact that there is no zero current crossing, an arc that appears upon...

  9. DC-Compensated Current Transformer.

    Science.gov (United States)

    Ripka, Pavel; Draxler, Karel; Styblíková, Renata

    2016-01-20

    Instrument current transformers (CTs) measure AC currents. The DC component in the measured current can saturate the transformer and cause gross error. We use fluxgate detection and digital feedback compensation of the DC flux to suppress the overall error to 0.15%. This concept can be used not only for high-end CTs with a nanocrystalline core, but it also works for low-cost CTs with FeSi cores. The method described here allows simultaneous measurements of the DC current component.

  10. DC injection into low voltage AC networks

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This report summarises the results of a study investigating the impact of levels of injected DC current injections on a low voltage AC distribution network systems in order to recommend acceptable limits of DC from microgeneration. Relevant literature is reviewed, and the impact of DC levels in distribution transformers, transformer modelling, and instrumental transformers are discussed. The impact of DC in residual current devices (RCD) and in domestic electricity watt hour meters is examined along with DC enhanced corrosion, corrosion failure, and the measurement of DC current injection. Sources of DC injection outlined include DC from computer power supplies, network faults, geomagnetic phenomena, lighting circuits/dimmers, and embedded generators.

  11. Isolated step-down DC -DC converter for electric vehicles

    Science.gov (United States)

    Kukovinets, O. V.; Sidorov, K. M.; Yutt, V. E.

    2018-02-01

    Modern motor-vehicle industrial sector is moving rapidly now towards the electricity-driving cars production, improving their range and efficiency of components, and in particular the step-down DC/DC converter to supply the onboard circuit 12/24V of electric vehicle from the high-voltage battery. The purpose of this article - to identify the best circuitry topology to design an advanced step-down DC/DC converters with the smallest mass, volume, highest efficiency and power. And this will have a positive effect on driving distance of electric vehicle (EV). On the basis of computational research of existing and implemented circuit topologies of step-down DC/DC converters (serial resonant converter, full bridge with phase-shifting converter, LLC resonant converter) a comprehensive analysis was carried out on the following characteristics: specific volume, specific weight, power, efficiency. The data obtained was the basis for the best technical option - LLC resonant converter. The results can serve as a guide material in the process of components design of the traction equipment for electric vehicles, providing for the best technical solutions in the design and manufacturing of converting equipment, self-contained power supply systems and advanced driver assistance systems.

  12. Borehole DC-12 hydrostratigraphic chart

    International Nuclear Information System (INIS)

    Gephart, R.E.

    1981-09-01

    This hydrostratigraphic chart identifies the basic stratigraphy and preliminary hydrologic testing results for Borehole DC-12. This borehole was cored through the Saddle Mountains and Wanapum basalt formations and into the Grande Ronde. Selected zones were hydrologically tested during coring

  13. Borehole DC-14 hydrostratigraphic chart

    International Nuclear Information System (INIS)

    Gephart, R.E.

    1981-09-01

    This hydrostratigraphic chart identifies the basic stratigraphy and preliminary hydrologic testing results for Borehole DC-14. This borehole was cored through the Saddle Mountains and Wanapum basalt formations and into the Grande Ronde. Selected zones were hydrologically tested during coring

  14. Borehole DC-15 hydrostratigraphic chart

    International Nuclear Information System (INIS)

    Gephart, R.E.

    1981-09-01

    This hydrostratigraphic chart identifies the basic stratigraphy and preliminary hydrologic testing results for Borehole DC-15. This borehole was cored through the Saddle Mountains and Wanapum basalt formations and into the Grande Ronde. Selected zones were hydrologically tested during coring

  15. Comparison study of moisture content, colour properties and essential oil compounds extracted by hydrodistillation and supercritical fluid extraction between stem and leaves of lemongrass (Cymbopogun citratus)

    Science.gov (United States)

    Kamaruddin, Shazlin; Mustapha, Wan Aida Wan; Haiyee, Zaibunnisa Abdul

    2018-04-01

    The objectives of this study were to compare the properties of moisture content, colour and essential oil compounds between stem and leaves of lemongrass (Cymbopogun citratus). The essential oil was extracted using two different methods which are hydrodistillation and supercritical fluid extraction (SFE). There was no significant difference of moisture content between stem and leaves of lemongrass. The lightness (L) and yellowness (+b) values of the stems were significantly higher (pleaves. The highest yield of essential oil was obtained by extraction using supercritical fluid extraction (SFE) in leaves (˜ 0.7%) by treatment at 1700psi and 50°C. The main compound of extracted essential oil was citral (geranial and neral).

  16. Effect of Inhaling Cymbopogon martinii Essential Oil and Geraniol on Serum Biochemistry Parameters and Oxidative Stress in Rats

    Directory of Open Access Journals (Sweden)

    Bruna Fernanda Murbach Teles Andrade

    2014-01-01

    Full Text Available The effects of the inhalation of Cymbopogon martinii essential oil (EO and geraniol on Wistar rats were evaluated for biochemical parameters and hepatic oxidative stress. Wistar rats were divided into three groups n=8: G1 was control group, treated with saline solution; G2 received geraniol; and G3 received C. martinii EO by inhalation during 30 days. No significant differences were observed in glycemia and triacylglycerol levels; G2 and G3 decreased P<0.05 total cholesterol level. There were no differences in serum protein, urea, aspartate aminotransferase activity, and total hepatic protein. Creatinine levels increased in G2 but decreased in G3. Alanine aminotransferase activity and lipid hydroperoxide were higher in G2 than in G3. Catalase and superoxide dismutase activities were higher in G3. C. martinii EO and geraniol increased glutathione peroxidase. Oxidative stress caused by geraniol may have triggered some degree of hepatic toxicity, as verified by the increase in serum creatinine and alanine aminotransferase. Therefore, the beneficial effects of EO on oxidative stress can prevent the toxicity in the liver. This proves possible interactions between geraniol and numerous chemical compounds present in C. martinii EO.

  17. Chemical composition and antimicrobial activity of Cymbopogon nardus citronella essential oil against systemic bacteria of aquatic animals

    Science.gov (United States)

    Wei, Lee Seong; Wee, Wendy

    2013-01-01

    Background & Objectives This paper describes chemical composition and antimicrobial activity of Cymbopogon nardus citronella essential oil against Edwardsiella spp. (n = 21), Vibrio spp. (n = 6), Aeromonas spp. (n = 2), Escherichia coli (n = 2), Salmonella spp. (n = 2), Flavobacterium spp. (n = 1), Pseudomonas spp. (n = 1) and Streptococcus spp. (n = 1) isolated from internal organs of aquatic animals. Due to the ban of antibiotics for aquaculture use, this study was carried out to evaluate the potential of citronella essential oil as alternative to commercial antibiotic use against systemic bacteria in cultured aquatic animals. Materials & Methods The essential oil of C. nardus was prepared by using the steam distillation method and the chemical composition of the essential oil was analyzed by gas chromatography–mass spectroscopy (GC–MS). Minimum inhibitory concentration (MIC) of the essential oil tested against bacterial isolates from various aquatic animals and ATCC type strains were determined using two-fold broth micro dilution method with kanamycin and eugenol as positive controls. Results A total of 22 chemical compounds were detected in C. nardus essential oil with 6-octenal, 3, 7-dimethyl- or citronellal representing the major compounds (29.6%). The MIC values of the citronella oil ranged from 0.244 µg/ml to 0.977 µg/ml when tested against the bacterial isolates. Conclusion The results of the present study revealed the potential of C. nardus essential oil as alternative to commercial antibiotics for aquaculture use. PMID:23825733

  18. Lemongrass (Cymbopogon flexuosus) essential oil demonstrated anti-inflammatory effect in pre-inflamed human dermal fibroblasts.

    Science.gov (United States)

    Han, Xuesheng; Parker, Tory L

    2017-06-01

    Lemongrass ( Cymbopogon flexuosus ) essential oil (LEO), which has citral as its main component, has exhibited anti-inflammatory effect in both animal and human cells. In this study, we evaluated the anti-inflammatory activity of a commercially available LEO in pre-inflamed human dermal fibroblasts. We first studied the impact of LEO on 17 protein biomarkers that are critically associated with inflammation and tissue remodeling. LEO significantly inhibited production of the inflammatory biomarkers vascular cell adhesion molecule 1 (VCAM-1), interferon gamma-induced protein 10 (IP-10), interferon-inducible T-cell alpha chemoattractant (I-TAC), and monokine induced by gamma interferon (MIG); decreased levels of the tissue remodeling biomarkers collagen-I and III, epidermal growth factor receptor (EGFR), and plasminogen activator inhibitor (PAI-1); and inhibited the immunomodulatory biomarker macrophage colony-stimulating factor (M-CSF). Furthermore, we studied the impact of LEO on genome-wide gene expression profiles. LEO significantly modulated global gene expression and robustly impacted signaling pathways, many of which are critical for inflammation and tissue remodeling processes. This study provides the first evidence of the anti-inflammatory activity of LEO in human skin cells and indicates that it is a good therapeutic candidate for treating inflammatory conditions of the skin.

  19. Microbial load and phytochemicals stability of camel hay (Cymbopogon Schoenanthus L) leaves as affected by gamma irradiation

    International Nuclear Information System (INIS)

    Musa, H. A. A.; Ahmed, E. E.; Osman, G. A. M.; Ludwig-muller, J.

    2010-01-01

    The influence of gamma irradiation on microbial load and chemical quality of camel hay (Cymbopogon schoenanthus) leaves was evaluated at doses of 0, 5,10, and 15 kGy in a cobalt-60 package irradiator. The results revealed that, immediately after irradiation, gamma irradiation was found to cause significant reduction in microbial load proportionate to the doses delivered. TLC analysis indicated that irradiation of camel hay leaves extract with 15 kGy doses of gamma radiation had no effect on flavonoids concentrations, however, increase in total phenols and tannins was observed. In addition, the chemical constituents of camel hay leaves as represented by HPLC retention time (min) at different wave lengths showed that the compounds of retention time 8.42, 29.08, 8.38, 16.93, 14.80 and 42.80 min remained approximately unchanged, while the compound of retention times 16.95 min was eliminated. The compounds of retention times 9.66, 2.03 and 29.35 min were decreased from 16.56 to 11.77, 14.06 to 9.88 and 8.25 to 2.88 min respectively. An increase in the chemical constituents, was observed in the compounds of the retention times 14.37 and 35.42 min from 33.76 to 40.11 and 5.64 to 10.05, respectively. (Author)

  20. Five-Level Active-Neutral-Point-Clamped DC/DC Converter for Medium-Voltage DC Grids

    DEFF Research Database (Denmark)

    Liu, Dong; Deng, Fujin; Chen, Zhe

    2017-01-01

    This paper proposes a five-level active-neutralpoint- clamped (5L-ANPC) dc/dc converter for applications in medium voltage dc (MVDC) grids. A modulation strategy is proposed for the 5L-ANPC dc/dc converter to generate multilevel voltage waveforms, which can effectively reduce voltage change rate dv...... effectively eliminate high voltage leaps caused by the dead time effect. In addition, a capacitor voltage control strategy is proposed for the 5L-ANPC dc/dc converter to ensure the balanced flying capacitor voltage and desired five-level voltage waveforms. Finally, simulation and experimental studies...

  1. 75 FR 63040 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-30, DC...

    Science.gov (United States)

    2010-10-14

    ... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-30, DC-10-30F (KDC-10... following new airworthiness directive (AD): 2010-21-13 McDonnell Douglas Corporation: Amendment 39-16473... November 18, 2010. Affected ADs (b) None. Applicability (c) This AD applies to McDonnell Douglas...

  2. 75 FR 68246 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

    Science.gov (United States)

    2010-11-05

    ...-1044; Directorate Identifier 2010-NM-033-AD] RIN 2120-AA64 Airworthiness Directives; McDonnell Douglas..., 2007) and adding the following new AD: McDonnell Douglas Corporation: Docket No. FAA-2010-1044.... Applicability (c) This AD applies to all McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

  3. Pulsewidth modulated DC-to-DC power conversion circuits, dynamics, and control designs

    CERN Document Server

    Choi, Byungcho

    2013-01-01

    This is the definitive reference for anyone involved in pulsewidth modulated DC-to-DC power conversion Pulsewidth Modulated DC-to-DC Power Conversion: Circuits, Dynamics, and Control Designs provides engineers, researchers, and students in the power electronics field with comprehensive and complete guidance to understanding pulsewidth modulated (PWM) DC-to-DC power converters. Presented in three parts, the book addresses the circuitry and operation of PWM DC-to-DC converters and their dynamic characteristics, along with in-depth discussions of control design of PWM DC-to

  4. Atmel Microcontroller Based Soft Switched PWM ZVS Full Bridge DC to DC Converter

    Directory of Open Access Journals (Sweden)

    DEEPAK KUMAR NAYAK

    2010-12-01

    Full Text Available This paper deals with the simulation and implementation of soft switched PWM ZVS full bridge DC to DC converter. The 48V DC is efficiently reduced to 12V DC using a DC to DC converter. This converter has advantages like reduced switching losses, stresses and EMI. Input DC is converted into high frequency AC and it is stepped down to 12V level. Later it is rectified using a full wave rectifier. Laboratory model of microcontroller based DC to DC converter is fabricated and tested. The experimental results are compared with the simulation results.

  5. 75 FR 60602 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

    Science.gov (United States)

    2010-10-01

    ... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10... adding the following new AD: 2010-20-14 McDonnell Douglas Corporation: Amendment 39-16449. Docket No. FAA... the airplanes identified in paragraphs (c)(1) and (c)(2) of this AD. (1) McDonnell Douglas Corporation...

  6. 75 FR 6160 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-15, DC...

    Science.gov (United States)

    2010-02-08

    ...-0032; Directorate Identifier 2009-NM-213-AD] RIN 2120-AA64 Airworthiness Directives; McDonnell Douglas...: McDonnell Douglas Corporation: Docket No. FAA-2010-0032; Directorate Identifier 2009-NM-213-AD. Comments Due... applies to McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-15, DC-10-30, DC-10-30F (KC-10A...

  7. 75 FR 38943 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-10, DC-10-10F, DC-10-30, DC...

    Science.gov (United States)

    2010-07-07

    ...-0672; Directorate Identifier 2010-NM-047-AD] RIN 2120-AA64 Airworthiness Directives; McDonnell Douglas...: McDonnell Douglas Corporation: Docket No. FAA-2010-0672; Directorate Identifier 2010-NM-047-AD. Comments Due... applies to McDonnell Douglas Corporation Model DC- 10-10, DC-10-10F, DC-10-30, DC-10-30F (KDC-10), DC-10...

  8. Light-weight DC to very high voltage DC converter

    Science.gov (United States)

    Druce, R.L.; Kirbie, H.C.; Newton, M.A.

    1998-06-30

    A DC-DC converter capable of generating outputs of 100 KV without a transformer comprises a silicon opening switch (SOS) diode connected to allow a charging current from a capacitor to flow into an inductor. When a specified amount of charge has flowed through the SOS diode, it opens up abruptly; and the consequential collapsing field of the inductor causes a voltage and current reversal that is steered into a load capacitor by an output diode. A switch across the series combination of the capacitor, inductor, and SOS diode closes to periodically reset the SOS diode by inducing a forward-biased current. 1 fig.

  9. Light-weight DC to very high voltage DC converter

    Energy Technology Data Exchange (ETDEWEB)

    Druce, Robert L. (Union City, CA); Kirbie, Hugh C. (Dublin, CA); Newton, Mark A. (Livermore, CA)

    1998-01-01

    A DC-DC converter capable of generating outputs of 100 KV without a transformer comprises a silicon opening switch (SOS) diode connected to allow a charging current from a capacitor to flow into an inductor. When a specified amount of charge has flowed through the SOS diode, it opens up abruptly; and the consequential collapsing field of the inductor causes a voltage and current reversal that is steered into a load capacitor by an output diode. A switch across the series combination of the capacitor, inductor, and SOS diode closes to periodically reset the SOS diode by inducing a forward-biased current.

  10. Radiated electromagnetic emissions of DC-DC converters

    International Nuclear Information System (INIS)

    Feld, L; Jussen, R; Karpinski, W; Klein, K; Sammet, J; Wlochal, M

    2010-01-01

    For the CMS tracker at SLHC a new powering scheme is considered to be mandatory to allow the detector to provide at least the same performance as today at the LHC. The baseline solution of CMS foresees the use of DC-DC converters to provide larger currents with smaller losses. An important component of most converters are inductors which, however, tend to radiate the switching noise generated by the converter. The emissions of different inductors have been measured and simulated, the coil design has been optimized and noise susceptibility measurements, with present CMS hardware, have been performed. This article summarizes the results.

  11. Pulse-width modulated DC-DC power converters

    CERN Document Server

    Kazimierczuk, Marian K

    2008-01-01

    This book studies switch-mode power supplies (SMPS) in great detail. This type of converter changes an unregulated DC voltage into a high-frequency pulse-width modulated (PWM) voltage controlled by varying the duty cycle, then changes the PWM AC voltage to a regulated DC voltage at a high efficiency by rectification and filtering. Used to supply electronic circuits, this converter saves energy and space in the overall system. With concept-orientated explanations, this book offers state-of-the-art SMPS technology and promotes an understanding of the principle operations of PWM converters,

  12. DESIGN OPTIMIZATION OF RESONANT DC-DC CONVERTERS

    OpenAIRE

    Belqasem Aljafari

    2016-01-01

    Resonant DC/DC converters are the class of converters, which have L-C resonant tank serving as a major part of the power conversion process. The fundamental concept of the resonant converter is that the circulating energy in an L-C resonant circuit is manageable by changing the operating frequency, and therefore the converter can condition the input power to the desired output voltage. The development in power conversion technology is steady demand for high power efficiency and high power den...

  13. DC grid for home applications

    Science.gov (United States)

    Elangovan, D.; Archana, R.; Jayadeep, V. J.; Nithin, M.; Arunkumar, G.

    2017-11-01

    More than fifty percent Indian population do not have access to electricity in daily lives. The distance between the power generating stations and the distribution centers forms one of the main reasons for lack of electrification in rural and remote areas. Here lies the importance of decentralization of power generation through renewable energy resources. In the present world, electricity is predominantly powered by alternating current, but most day to day devices like LED lamps, computers and electrical vehicles, all run on DC power. By directly supplying DC to these loads, the number of power conversion stages was reduced, and overall system efficiency increases. Replacing existing AC network with DC is a humongous task, but with power electronic techniques, this project intends to implement DC grid at a household level in remote and rural areas. Proposed work was designed and simulated successfully for various loads amounting to 250 W through appropriate power electronic convertors. Maximum utilization of the renewable sources for domestic and commercial application was achieved with the proposed DC topology.

  14. Linking DC together with TRSL

    DEFF Research Database (Denmark)

    Haxthausen, Anne; Yong, Xia

    1999-01-01

    In this talk we present a method for linking the Duration Calculus together with the Timed RAISE Specification Language. Duration Calculus (DC) [ZHR91] is an interval-based real time logic, which can be used naturally in capturing and eliciting users' real time requirements in the form of constra......In this talk we present a method for linking the Duration Calculus together with the Timed RAISE Specification Language. Duration Calculus (DC) [ZHR91] is an interval-based real time logic, which can be used naturally in capturing and eliciting users' real time requirements in the form.......TRSL is a real-time extension of the RAISE Specification Language (RSL) [Rlg92] which together with its associated method [Rmg95]and tools has shown to be very useful in the industrial development of software systems. Therefore, a promising approach for the development of real-time systemscould be to use DC...... for high-level specifications of real-time requirementsand TRSL for specifying real-time implementations in the form of timed communicating concurrent processes.In order to link DC and TRSL together in a well-founded way, we formally define what it means for a TRSL process to satisfy a DC requirement...

  15. Óleos essenciais de Cymbopogon nardus, Cinnamomum zeylanicum e Zingiber officinale: composição, atividades antioxidante e antibacteriana Essential oils of Cinnamomum zeylanicum, Cymbopogon nardus and Zingiber officinale: composition, antioxidant and antibacterial activities

    Directory of Open Access Journals (Sweden)

    Milene Aparecida Andrade

    2012-06-01

    Full Text Available Objetivou-se neste estudo caracterizar quimicamente e avaliar as atividades antioxidante e antibacteriana dos óleos essenciais de citronela (Cymbopogon nardus, canela (Cinnamomum zeylanicum e gengibre (Zingiber officinale. A obtenção do óleo essencial foi realizada utilizando a técnica de hidrodestilação por meio do aparelho de Clevenger modificado e a identificação e quantificação dos constituintes pelas análises em CG/EM e CG-DIC. A avaliação da atividade antibacteriana foi realizada por meio da técnica difusão cavidade em ágar, utilizando os microrganismos Staphylococcus aureus ATCC 6538, Listeria monocytogenes ATCC 19117, Escherichia coli ATCC 11229, Salmonella Cholerasuis ATCC 6539 e Pseudomonas aeruginosa ATCC 15442. A atividade antioxidante foi avaliada utilizando sistema β-caroteno/ácido linoléico e o método de seqüestro de radicais DPPH. Nas análises cromatográficas, os constituintes majoritários encontrados no óleo essencial de C. nardus foram citronelal (47,12%, geraniol (18,56% e citronelol (11,07%, no óleo essencial de C. zeylanicum foram identificados (E- cinamaldeído (77,72%, acetato de (E-cinamila (5,99% e o monoterpenóide 1,8-cineol (4,66% e, para Z. officinale os majoritários foram geranial (25,06%, neral (16,47%, 1,8-cineol (10,98%, geraniol (8,51%, acetato de geranila (4,19% e o canfeno (4,30%. Os óleos essenciais apresentaram atividade antibacteriana tanto para bactérias Gram-negativas como para bactérias Gram-positivas, sendo que o óleo essencial de C. zeylanicum foi o mais eficiente. A atividade antioxidante foi evidenciada pelo teste β-caroteno/ácido linoléico, respectivamente, para C. nardus, seguido de Z. officinale e C. zeylanicum, e pelo teste do DPPH foi observada apenas para C. nardus.The aims of this study were to chemically characterize and to evaluate the antioxidant and antibacterial activities of the citronella (Cymbopogon nardus, cinnamon (Cinnamomum zeylanicum and ginger

  16. Modeling and analysis of fractional order DC-DC converter.

    Science.gov (United States)

    Radwan, Ahmed G; Emira, Ahmed A; AbdelAty, Amr M; Azar, Ahmad Taher

    2017-07-11

    Due to the non-idealities of commercial inductors, the demand for a better model that accurately describe their dynamic response is elevated. So, the fractional order models of Buck, Boost and Buck-Boost DC-DC converters are presented in this paper. The detailed analysis is made for the two most common modes of converter operation: Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM). Closed form time domain expressions are derived for inductor currents, voltage gain, average current, conduction time and power efficiency where the effect of the fractional order inductor is found to be strongly present. For example, the peak inductor current at steady state increases with decreasing the inductor order. Advanced Design Systems (ADS) circuit simulations are used to verify the derived formulas, where the fractional order inductor is simulated using Valsa Constant Phase Element (CPE) approximation and Generalized Impedance Converter (GIC). Different simulation results are introduced with good matching to the theoretical formulas for the three DC-DC converter topologies under different fractional orders. A comprehensive comparison with the recently published literature is presented to show the advantages and disadvantages of each approach. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  17. An Integrated Multifunctional Bidirectional AC/DC and DC/DC Converter for Electric Vehicles Applications

    Directory of Open Access Journals (Sweden)

    Liwen Pan

    2016-06-01

    Full Text Available This paper presents an on-board vehicular battery charger that integrates bidirectional AC/DC converter and DC/DC converter to achieve high power density for application in electric vehicles (EVs. The integrated charger is able to transfer electrical energy between the battery pack and the electric traction system and to function as an AC/DC battery charger. The integrated charger topology is presented and the design of passive components is discussed. The control schemes are developed for motor drive system and battery-charging system with a power pulsation reduction circuit. Simulation results in MATLAB/Simulink and experiments on a 30-kW motor drive and 3.3-kW AC/DC charging prototype validate the performance of the proposed technology. In addition, power losses, efficiency comparison and thermal stress for the integrated charger are illustrated. The results of the analyses show the validity of the advanced integrated charger for electric vehicles.

  18. Switching coordination of distributed dc-dc converters for highly efficient photovoltaic power plants

    Science.gov (United States)

    Agamy, Mohammed; Elasser, Ahmed; Sabate, Juan Antonio; Galbraith, Anthony William; Harfman Todorovic, Maja

    2014-09-09

    A distributed photovoltaic (PV) power plant includes a plurality of distributed dc-dc converters. The dc-dc converters are configured to switch in coordination with one another such that at least one dc-dc converter transfers power to a common dc-bus based upon the total system power available from one or more corresponding strings of PV modules. Due to the coordinated switching of the dc-dc converters, each dc-dc converter transferring power to the common dc-bus continues to operate within its optimal efficiency range as well as to optimize the maximum power point tracking in order to increase the energy yield of the PV power plant.

  19. Behavior of detoxifying enzymes of Aedes aegypti exposed to girgensohnine alkaloid analog and Cymbopogon flexuosus essential oil.

    Science.gov (United States)

    Carreño Otero, Aurora L; Palacio-Cortés, Angela Maria; Navarro-Silva, Mario Antonio; Kouznetsov, Vladimir V; Duque L, Jonny E

    2018-01-01

    Because mosquito control depend on the use of commercial insecticides and resistance has been described in some of them, there is a need to explore new molecules no resistant. In vivo effects of girgensohnine analog 2-(3,4-dimethoxyphenyl)-2-(piperidin-1-yl)acetonitrile DPPA and Cymbopogon flexuosus essential oil CFEO, on the detoxifying enzymes acetylcholinesterase (AChE), glutathione-S-transferase (GST), nonspecific esterases (α- and β-), mixed function oxidases (MFO) and p-NPA esterases were evaluated on a Rockefeller (Rock) and wild Aedes aegypti population from Santander, Colombia (WSant). The action was tested after 24h of exposure at concentrations of 20.10, 35.18 and 70.35mgL -1 of DPPA and 18.45, 30.75 and 61.50mgL -1 of CFEO, respectively. It was found that AChE activity of Rock and WSant was not influenced by the evaluated concentration of DPPA and CFEO (p>0.05), while MFO activity was significantly affected by all CFEO concentrations in WSant (p<0.05). GST, α- and β-esterase activities were affected in Rock exposed at the highest CFEO concentration, this concentration also modified β-esterases activity of WSant. DPPA and CFEO sublethal doses induced inhibition of AChE activity on untreated larvae homogenate from 12 to 20% and 18 to 26%, respectively. For untreated adult homogenate, the inhibition activity raised up to 14 to 27% for DPPA and 26 to 34% for CFEO. Elevated levels of detoxifying enzymes, found when CFEO was evaluated, showed a larval sensitivity not observed by the pure compound suggesting that DPPA, contrary to CFEO, was not recognized, transformed or eliminated by the evaluated detoxifying enzymes. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Growth inhibition and morphological alterations of Trichophyton rubrum induced by essential oil from Cymbopogon winterianus Jowitt ex Bor

    Directory of Open Access Journals (Sweden)

    Fillipe de Oliveira Pereira

    2011-03-01

    Full Text Available Trichophyton rubrum is one of the most common fungi causer of dermatophytosis, mycosis that affect humans and animals around the world. Researches aiming new products with antifungal activity become necessary to overcome difficulties on treatment of these infections. Accordingly, this study aimed to investigate the antifungal activity of essential oil from Cymbopogon winterianus against the dermatophyte T. rubrum. The antifungal screening was performed by solid medium diffusion method with 16 T. rubrum strains, minimum inhibitory concentration (MIC and minimum fungicide concentration (MFC were determined using the microdilution method. The effects on mycelial dry weight and morphology were also observed. Screening showed essential oil in natura inhibited all the tested strains, with inhibition zones between 24-28 mm diameter. MIC50 and MIC90 values of the essential oil were 312 µg/mL for nearly all the essayed strains (93.75 % while the MFC50 and MFC90 values were about eight times higher than MIC for all tested strains. All tested essential oil concentrations managed to inhibit strongly the mycelium development. Main morphological changes on the fungal strains observed under light microscopy, which were provided by the essential oil include loss of conidiation, alterations concerning form and pigmentation of hyphae. In the oil presence, colonies showed folds, cream color and slightly darker than the control, pigment production was absent on the reverse and with evident folds. It is concluded that C. winterianus essential oil showed activity against T. rubrum. Therefore, it could be known as potential antifungal compound especially for protection against dermatophytosis.

  1. Application of Distributed DC/DC Electronics in Photovoltaic Systems

    Science.gov (United States)

    Kabala, Michael

    In a typical residential, commercial or utility grade photovoltaic (PV) system, PV modules are connected in series and in parallel to form an array that is connected to a standard DC/AC inverter, which is then connected directly to the grid. This type of standard installation; however, does very little to maximize the energy output of the solar array if certain conditions exist. These conditions could include age, temperature, irradiance and other factors that can cause mismatch between PV modules in an array that severely cripple the output power of the system. Since PV modules are typically connected in series to form a string, the output of the entire string is limited by the efficiency of the weakest module. With PV module efficiencies already relatively low, it is critical to extract the maximum power out of each module in order to make solar energy an economically viable competitor to oil and gas. Module level DC/DC electronics with maximum power point (MPP) tracking solves this issue by decoupling each module from the string in order for the module to operate independently of the geometry and complexity of the surrounding system. This allows each PV module to work at its maximum power point by transferring the maximum power the module is able to deliver directly to the load by either boosting (stepping up) the voltage or bucking (stepping down) the voltage. The goal of this thesis is to discuss the development of a per-module DC/DC converter in order to maximize the energy output of a PV module and reduce the overall cost of the system by increasing the energy harvest.

  2. Voltage Weak DC Distribution Grids

    NARCIS (Netherlands)

    Hailu, T.G.; Mackay, L.J.; Ramirez Elizondo, L.M.; Ferreira, J.A.

    2017-01-01

    This paper describes the behavior of voltage weak DC distribution systems. These systems have relatively small system capacitance. The size of system capacitance, which stores energy, has a considerable effect on the value of fault currents, control complexity, and system reliability. A number of

  3. Compact integrated dc SQUID gradiometer

    Science.gov (United States)

    de Waal, V. J.; Klapwijk, T. M.

    1982-10-01

    An all-niobium integrated system of first-order gradiometer and dc suprconducting quantum interference device (SQUID) has been developed. It is relatively simple to fabricate, has an overall size of 17×12 mm and a sensitivity of 3.5×10-12 T m-1 Hz-1/2.

  4. Compact integrated dc SQUID gradiometer

    Energy Technology Data Exchange (ETDEWEB)

    de Waal, V.J.; Klapwijk, T.M.

    1982-10-01

    An all-niobium integrated system of first-order gradiometer and dc suprconducting quantum interference device (SQUID) has been developed. It is relatively simple to fabricate, has an overall size of 17 x 12 mm and a sensitivity of 3.5 x 10/sup -12/ T m/sup -1/ Hz/sup -1/2/.

  5. Experiments with a DC Motor

    Science.gov (United States)

    Kraftmakher, Yaakov

    2010-01-01

    Experiments with an electric motor provide good opportunity to demonstrate some basic laws of electricity and magnetism. The aim of the experiments with a low-power dc motor is to show how the motor approaches its steady rotation and how its torque, mechanical power and efficiency depend on the rotation velocity. The tight relationship between the…

  6. Borehole DC-6 hydrostratigraphic chart

    International Nuclear Information System (INIS)

    Gephart, R.E.

    1981-09-01

    This hydrostratigraphic chart for Borehole DC-6 identifies the basic stratigraphy and preliminary hydrologic test results. This borehole was cored for obtaining stratigraphic data and only that portion within the Grande Ronde formation remains open for hydrologic testing. The upper two formations were cased and cemented off

  7. DC motor operation controlled from a DC/DC power converter in pulse mode with low duty cycle

    OpenAIRE

    Stefanov, Goce; Kukuseva, Maja; Citkuseva Dimitrovska, Biljana

    2016-01-01

    In this paper pulse mode of operation of DC motor controlled by DC/DC power converter is analyzed. DC motor operation with time intervals in which the motor operates without output load is of interest. In this mode it is possible the motor to restore energy. Also, in the paper are represented calculations for the amount of the restored energy in the pulse mode operation of the motor for different duty cycles.

  8. DC to DC power converters and methods of controlling the same

    Science.gov (United States)

    Steigerwald, Robert Louis; Elasser, Ahmed; Sabate, Juan Antonio; Todorovic, Maja Harfman; Agamy, Mohammed

    2012-12-11

    A power generation system configured to provide direct current (DC) power to a DC link is described. The system includes a first power generation unit configured to output DC power. The system also includes a first DC to DC converter comprising an input section and an output section. The output section of the first DC to DC converter is coupled in series with the first power generation unit. The first DC to DC converter is configured to process a first portion of the DC power output by the first power generation unit and to provide an unprocessed second portion of the DC power output of the first power generation unit to the output section.

  9. Analysis of a high power, resonant DC-DC converter for DC wind turbines

    DEFF Research Database (Denmark)

    Dincan, Catalin Gabriel; Kjær, Philip Carne; Chen, Yu-Hsing

    2018-01-01

    This paper is introducing a new method of operation for a series resonant converter, with intended application in megawatt high-voltage DC wind turbines. Compared to a frequency controlled series resonant converter operated in sub resonant mode, the method (entitled pulse removal technique) allows...

  10. Dilation and Curettage (D&C)

    Science.gov (United States)

    ... For Patients About ACOG Dilation and Curettage (D&C) Home For Patients Search FAQs Dilation and Curettage ( ... February 2016 PDF Format Dilation and Curettage (D&C) Special Procedures What is dilation and curettage (D& ...

  11. Hierarchical Power Sharing Control in DC Microgrids

    DEFF Research Database (Denmark)

    Peyghami, Saeed; Mokhtari, Hossein; Blaabjerg, Frede

    2016-01-01

    Because of the advances in power electronics, DC-based power systems, have been used in industrial applications such as data centers [18], space applications [10], aircraft [12], offshore wind farms, electric vehicles [56], DC home systems [5, 20], and high-voltage DC transmission systems...

  12. Characterising and modelling extended conducted electromagnetic interference in densely packed DC-DC converter

    CSIR Research Space (South Africa)

    Grobler, Inus

    2013-09-01

    Full Text Available . The military specified DC-DC converters are applicable, spanning from 100 W handheld power managers up to 2 kW DC-DC battery chargers. Circuit layout high frequency effects as well as high frequency impedances of the power components were characterised...

  13. Full wave dc-to-dc converter using energy storage transformers

    Science.gov (United States)

    Moore, E. T.; Wilson, T. G.

    1969-01-01

    Full wave dc-to-dc converter, for an ion thrustor, uses energy storage transformers to provide a method of dc-to-dc conversion and regulation. The converter has a high degree of physical simplicity, is lightweight and has high efficiency.

  14. A DC-DC Conversion Powering Scheme for the CMS Phase-1 Pixel Upgrade

    CERN Document Server

    Feld, Lutz Werner; Marcel Friedrichs; Richard Hensch; Karpinski, Waclaw; Klein, Katja; Sammet, Jan Domenik; Wlochal, Michael

    2012-01-01

    The powering scheme of the CMS pixel detector will be described, and the performance of prototype DC-DC buck converters will be presented, including power efficiency, system tests with DC-DC converters and pixel modules, thermal management, reliability at low temperature, and studies of potential frequency locking betwe...

  15. Transformerless dc-Isolated Converter

    Science.gov (United States)

    Rippel, Wally E.

    1987-01-01

    Efficient voltage converter employs capacitive instead of transformer coupling to provide dc isolation. Offers buck/boost operation, minimal filtering, and low parts count, with possible application in photovoltaic power inverters, power supplies and battery charges. In photovoltaic inverter circuit with transformerless converter, Q2, Q3, Q4, and Q5 form line-commutated inverter. Switching losses and stresses nil because switching performed when current is zero.

  16. AC-DC PFC Converter Using Combination of Flyback Converter and Full-bridge DC-DC Converter

    Directory of Open Access Journals (Sweden)

    Moh. Zaenal Efendi

    2014-06-01

    Full Text Available This paper presents a combination of power factor correction converter using Flyback converter and Full-bridge dc-dc converter in series connection. Flyback converter is operated in discontinuous conduction mode so that it can serve as a power factor correction converter and meanwhile Full-bridge dc-dc converter is used for dc regulator. This converter system is designed to produce a 86 Volt of output voltage and 2 A of output current. Both simulation and experiment results show that the power factor of this converter achieves up to 0.99 and meets harmonic standard of IEC61000-3-2. Keywords: Flyback Converter, Full-bridge DC-DC Converter, Power Factor Correction.

  17. A Feed-Forward Control Realizing Fast Response for Three-Branch Interleaved DC-DC Converter in DC Microgrid

    Directory of Open Access Journals (Sweden)

    Haojie Wang

    2016-07-01

    Full Text Available It is a common practice for storage batteries to be connected to DC microgrid buses through DC-DC converters for voltage support on islanded operation mode. A feed-forward control based dual-loop constant voltage PI control for three-branch interleaved DC-DC converters (TIDC is proposed for storage batteries in DC microgrids. The working principle of TIDC is analyzed, and the factors influencing the response rate based on the dual-loop constant voltage control for TIDC are discussed, and then the method of feed-forward control for TIDC is studied to improve the response rate for load changing. A prototype of the TIDC is developed and an experimental platform is built. The experiment results show that DC bus voltage sags or swells caused by load changing can be reduced and the time for voltage recovery can be decreased significantly with the proposed feed-forward control.

  18. A Feed-Forward Control Realizing Fast Response for Three-Branch Interleaved DC-DC Converter in DC Microgrid

    DEFF Research Database (Denmark)

    Wang, Haojie; Han, Minxiao; Yan, Wenli

    2016-01-01

    It is a common practice for storage batteries to be connected to DC microgrid buses through DC-DC converters for voltage support on islanded operation mode. A feed-forward control based dual-loop constant voltage PI control for three-branch interleaved DC-DC converters (TIDC) is proposed...... for storage batteries in DC microgrids. The working principle of TIDC is analyzed, and the factors influencing the response rate based on the dual-loop constant voltage control for TIDC are discussed, and then the method of feed-forward control for TIDC is studied to improve the response rate for load...... changing. A prototype of the TIDC is developed and an experimental platform is built. The experiment results show that DC bus voltage sags or swells caused by load changing can be reduced and the time for voltage recovery can be decreased significantly with the proposed feed-forward control....

  19. Essential Oil of Cymbopogon nardus (L. Rendle: A Strategy to Combat Fungal Infections Caused by Candida Species

    Directory of Open Access Journals (Sweden)

    Luciani Gaspar De Toledo

    2016-08-01

    Full Text Available Background: The incidence of fungal infections, especially those caused by Candida yeasts, has increased over the last two decades. However, the indicated therapy for fungal control has limitations. Hence, medicinal plants have emerged as an alternative in the search for new antifungal agents as they present compounds, such as essential oils, with important biological effects. Published data demonstrate important pharmacological properties of the essential oil of Cymbopogon nardus (L. Rendle; these include anti-tumor, anti-nociceptive, and antibacterial activities, and so an investigation of this compound against pathogenic fungi is interesting. Objective: The aim of this study was to evaluate the chemical composition and biological potential of essential oil (EO obtained from the leaves of C. nardus focusing on its antifungal profile against Candida species. Methods: The EO was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS. Testing of the antifungal potential against standard and clinical strains was performed by determining the minimal inhibitory concentration (MIC, time-kill, inhibition of Candida albicans hyphae growth, and inhibition of mature biofilms. Additionally, the cytotoxicity was investigated by the IC50 against HepG-2 (hepatic and MRC-5 (fibroblast cell lines. Results: According to the chemical analysis, the main compounds of the EO were the oxygen-containing monoterpenes: citronellal, geranial, geraniol, citronellol, and neral. The results showed important antifungal potential for all strains tested with MIC values ranging from 250 to 1000 μg/mL, except for two clinical isolates of C. tropicalis (MIC > 1000 μg/mL. The time-kill assay showed that the EO inhibited the growth of the yeast and inhibited hyphal formation of C. albicans strains at concentrations ranging from 15.8 to 1000 μg/mL. Inhibition of mature biofilms of strains of C. albicans, C. krusei and C. parapsilosis occurred

  20. FLYWHEEL AND A DC MACHINE

    Directory of Open Access Journals (Sweden)

    IVAN ALCALÁ

    2014-01-01

    Full Text Available Este artículo describe el análisis, modelado y simulación de un vehículo eléctrico (EV enfocado al desarrollo de un banco de pruebas para reproducir la dinámica del EV. El banco está formado por un drive de motor de inducción (IM acoplado directamente a una máquina de DC y a un volante de inercia a través de una transmisión. El volante de inercia y la máquina de DC reproducen la dinámica y las fuerzas que actúan en el vehículo. Se propone una metodología para diseñar un banco de pruebas de EV para estudiar el comportamiento de vehículos eléctricos cercano a las condiciones de operación reales. El análisis de las fuerzas en el EV en conjunto con la máquina DC define las condiciones de operación del EV. El modelado y la simulación son desarrollados en MATLAB/Simulink, el banco de pruebas implementado es controlado por un DSP. Finalmente, los resultados de simulación y experimentales obtenidos validan el funcionamiento del banco de prueba.

  1. Quasi-Z-Source Half-Bridge DC-DC Converter for Photovoltaic Applications

    OpenAIRE

    Vinnikov, D; Chub, A; Husev, O; Zaķis, J

    2015-01-01

    This paper presents a novel quasi-Z-source halfbridge galvanically isolated DC-DC converter intended for the photovoltaic applications. The topology could be envisioned as an alternative to the boost half-bridge DC-DC converter but the benefit of its symmetric structure reduces the threat of transformer saturation due to the dc flux. The proposed converter features the continuous input current and could be used either with one or two input voltage sources.

  2. Control of the DC-DC Converter used into Energy Generation System

    International Nuclear Information System (INIS)

    Bizon, Nicu; Oproescu, Mihai

    2006-01-01

    This paper presents an investigation of the DC-DC Converter controller used into Energy Generation System. The full bridge is used into an Energy Generation System (EGS) as second power interface between the energy source and the high DC bus. The simulation results show that the DC-DC Converter behavior can be improved using a well designed PI control surface. The used Simulink models for the EGS blocks and some design considerations are presented, too. (authors)

  3. Studies on the influence of combustion bowl modification for the operation of Cymbopogon flexuosus biofuel based diesel blends in a DI diesel engine

    International Nuclear Information System (INIS)

    Dhinesh, B.; Annamalai, M.; Lalvani, Isaac JoshuaRamesh; Annamalai, K.

    2017-01-01

    Highlights: • A novel biofuel, Cymbopogon flexuosus is used as an alternative energy source. • C20-D80 + 20 ppm profile stayed close to diesel fuel with BB. • Three different combustion bowl CB1, CB2, and CB3 were considered. • Resulting in higher thermal efficiency and lower HC, CO, emission. • Reduction of oxides of nitrogen and smoke emission for C20-D80 + 20 ppm and CB2. - Abstract: The aim of this experimental work is to figure out the optimized the combustion bowl geometry on a constant speed diesel engine for its efficient functioning with a novel biofuel. The novel biofuel considered for this research work was Cymbopogon flexuosus biofuel. To improve the performance level, 20% Cymbopogon flexuosus biofuel was blended with 80% of diesel fuel (C20-D80) and to further reduce the emission magnitude, 20 ppm of cerium oxide was added to the blended fuel (C20-D80 + 20 ppm). For this study four different combustion bowls were designed based on the keen literature survey. They were hemispherical combustion bowl (BB), shallow depth re-entrant combustion bowl (CB1), Toroidal re-entrant combustion bowl (CB2), Toroidal combustion bowl (CB3). Based on the experimental evaluation, the results have been discussed for low load and full load conditions for better understanding. Regarding the fuel modification, C20-D80 + 20 ppm resulted in better engine characteristics owing to combined effect of the oxygen molecule bearing fuel and superior thermal stability and activation energy of the cerium oxide nanoparticle. Of the various bowls considered for the tests, the combustion bowl CB2 showed superior performance and emission reduction compared with its competitors CB1, CB2, and BB. It could have ascribed to the better mixing rate, gain of swirl velocity and the turbulence level of the bowl. CB2 resulted in higher BTE and lower BSEC of 4.1% and 12.02% in low and full load conditions for C20-D80 + 20 ppm. Emission reduction observed was 17% of HC, 43.66% of CO and

  4. ZVS Operating Region of Multiresonant DC/DC Boost Conveter

    Directory of Open Access Journals (Sweden)

    Elzbieta Szychta

    2007-01-01

    Full Text Available Electromagnetic phenomena that occur during stable operation in resonant circuits of multiresonant ZVS boost converter are described, which can be applied in many fields of the needs of DC voltage electricity. The operating region of the converter is defined which assures the circuit’s operation in which semiconductor elements are switched at zero voltage (ZVS. Conditions delimiting the ZVS operating region are provided. Analysis of the circuit’s operation is based on results of simulation testing by means of Simplorer software.

  5. A Feedback Passivation Design for DC Microgrid and Its DC/DC Converters

    Directory of Open Access Journals (Sweden)

    Feifan Ji

    2016-12-01

    Full Text Available There are difficulties in analyzing the stability of microgrids since they are located on various network structures. However, considering that the network often consists of passive elements, the passivity theory is applied in this paper to solve the above-mentioned problem. It has been formerly shown that when the network is weakly strictly positive real (WSPR, the DC microgrid is stable if all interfaces between the microgrid and converters are made to be passive, which is called interface passivity. Then, the feedback passivation method is proposed for the controller design of various DC–DC converters to achieve the interface passivity. The interface passivity is different from the passivity of closed-loop systems on which the passivity based control (PBC concentrates. The feedback passivation design is detailed for typical buck converters and boost converters in terms of conditions that the controller parameters should satisfy. The theoretical results are verified by a hardware-in-loop real-time labotray (RTLab simulation of a DC microgrid with four generators.

  6. Artificial neural network control of sab dc/dc converter

    International Nuclear Information System (INIS)

    Mahar, M.A.; Abro, M.R.; Larik, A.S.

    2009-01-01

    The latest development of power semiconductor devices enable the modern power electronic converters to withstand high voltage and high power applications. Power electronic converters are mostly periodic variable structure systems due to their switched operations. The main drawback of these converters is the generation of oscillations which are developed during the operation of the converters under nonlinear situations. To handle these nonlinearities, various researchers have proposed different control techniques. Power electronic designers are devoting in the further development of converter topologies and their control techniques. SAB (Single Active Bridge) DC/DC converter is a new topology recently introduced by Demetriades. This topology is used in high voltage and high power applications. Because of its smart features, SAB converter has recently drawn attention of many researchers. However, during the operation of SAB converter severe oscillations are generated. In this research work, a novel NNC (Neural Network Controller) model is developed for SAB converter to minimize oscillations generated during its operation. NNC is believed to be an advanced nonlinear and robust controller which has the ability to map the nonlinear behaviour in a negligible response time. The performance of SAB converter with NNC is tested under dynamic region by considering the reference voltage variation and duty ratio variation. The SAB converter is implemented and simulated in MATLAB/Simulink. The simulated results are presented. (author)

  7. Experiments with a dc motor

    International Nuclear Information System (INIS)

    Kraftmakher, Yaakov

    2010-01-01

    Experiments with an electric motor provide good opportunity to demonstrate some basic laws of electricity and magnetism. The aim of the experiments with a low-power dc motor is to show how the motor approaches its steady rotation and how its torque, mechanical power and efficiency depend on the rotation velocity. The tight relationship between the mechanical and electrical parameters of the motor is clearly seen. The measurements are carried out with the ScienceWorkshop data-acquisition system and the DataStudio software from PASCO scientific. The experiments are well related to university courses of electricity and magnetism and can be used in undergraduate laboratories or for lecture demonstrations.

  8. Using PBL to Improve Educational Outcomes and Student Satisfaction in the Teaching of DC/DC and DC/AC Converters

    Science.gov (United States)

    Martinez-Rodrigo, Fernando; Herrero-De Lucas, Luis Carlos; de Pablo, Santiago; Rey-Boue, Alexis B.

    2017-01-01

    This paper examines the question of how to use project-based learning to increase student performance and satisfaction in a power electronics course addressing the topics of dc/dc and dc/ac converters, the assembly of a dc/dc converter, and the use of a commercial speed drive. A detailed presentation of the methodology is shown, and the results…

  9. Hierarchical Velocity Control Based on Differential Flatness for a DC/DC Buck Converter-DC Motor System

    Directory of Open Access Journals (Sweden)

    R. Silva-Ortigoza

    2014-01-01

    Full Text Available This paper presents a hierarchical controller that carries out the angular velocity trajectory tracking task for a DC motor driven by a DC/DC Buck converter. The high level control is related to the DC motor and the low level control is dedicated to the DC/DC Buck converter; both controls are designed via differential flatness. The high level control provides a desired voltage profile for the DC motor to achieve the tracking of a desired angular velocity trajectory. Then, a low level control is designed to ensure that the output voltage of the DC/DC Buck converter tracks the voltage profile imposed by the high level control. In order to experimentally verify the hierarchical controller performance, a DS1104 electronic board from dSPACE and Matlab-Simulink are used. The switched implementation of the hierarchical average controller is accomplished by means of pulse width modulation. Experimental results of the hierarchical controller for the velocity trajectory tracking task show good performance and robustness against the uncertainties associated with different system parameters.

  10. The Topologies Research of a Soft Switching Bidirectional DC/DC Converter

    DEFF Research Database (Denmark)

    Zhang, Qi; Zhang, Yongping; Sun, Xiangdong

    2017-01-01

    A soft-switching solution implemented to the traditional bidirectional DC/DC converter is developed. The soft-switching cell, which composed of three auxiliary switches, one resonant capacitor and one resonant inductor, is equipped in the traditional bidirectional DC/DC converter to realize circuit...... circle. And the proposed topology of bidirectional soft-switching dc-dc converter(TASBC) performs ideal soft switching at boost operations. The characteristics of the proposed converter has been verified by MATLAB simulations and experimental results....

  11. Elimination of output voltage oscillations in DC-DC converter using PWM with PI controller

    Directory of Open Access Journals (Sweden)

    Sreenivasappa Veeranna Bhupasandra

    2010-01-01

    Full Text Available In this paper the SIMULINK model of a PWM controlled DC-DC converter is modeled using switching function concept to control the speed of the DC motor. The presence of the voltage oscillation cycles due to higher switching frequency in the DC-DC converter is identified. The effect of these oscillations on the output voltage of the converter, Armature current, Developed torque and Speed of the DC motor is analyzed. In order to minimize the oscillation cycles the PI controller is proposed in the PWM controller.

  12. Chaos analysis and chaotic EMI suppression of DC-DC converters

    CERN Document Server

    Zhang, Bo

    2014-01-01

    Introduces chaos theory, its analytical methods and the means to apply chaos to the switching power supply design DC-DC converters are typical switching systems which have plenty of nonlinear behaviors, such as bifurcation and chaos. The nonlinear behaviors of DC-DC converters have been studied heavily over the past 20 years, yet researchers are still unsure of the practical application of bifurcations and chaos in switching converters. The electromagnetic interference (EMI), which resulted from the high rates of changes of voltage and current, has become a major design criterion in DC-DC co

  13. [Effectiveness of aqueous extracts of aromatic and medicinal plants against tomato grey mould in Morocco].

    Science.gov (United States)

    Kasmi, Manal; Aourach, Mohammed; El Boukari, Mohammed; Barrijal, Said; Essalmani, Haiat

    2017-08-01

    Grey mould is a major disease threatening the Moroccan tomato; this disease is often controlled by fungicides. However, the latter are a real danger to human health and environment. Thus, this study is part of the research of harmless alternatives such extracts of aromatic and medicinal plants (Lavandula officinalis, Thymus vulgaris, Cymbopogon citratus, and Melissa officinalis). In this study, the extracts of four medicinal and aromatic plants were tested for their antifungal potency in vitro and in vivo in order to select the most effective. The results show that, in vitro, the Lavandula officinalis, Thymus vulgaris and Cymbopogon citratus aqueous extracts all possess significant antifungal activity, whereas Melissa officinalis shows the least effective. Also in vivo only the aqueous extract of Cymbopogon citratus proves most effective against B. cinerea on tomato fruit. The test of the plants confirms that aqueous extracts of Cymbopogon citratus and Thymus vulgaris are most effective, while the aqueous extracts of Melissa officinalis and Lavandula officinalis always seem to be the least effective. Therefore, the aqueous extracts of Cymbopogon citratus and Thymus vulgaris are the most envisaged for the biological control of grey mould. Copyright © 2017 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.

  14. Simultaneous distribution of AC and DC power

    Science.gov (United States)

    Polese, Luigi Gentile

    2015-09-15

    A system and method for the transport and distribution of both AC (alternating current) power and DC (direct current) power over wiring infrastructure normally used for distributing AC power only, for example, residential and/or commercial buildings' electrical wires is disclosed and taught. The system and method permits the combining of AC and DC power sources and the simultaneous distribution of the resulting power over the same wiring. At the utilization site a complementary device permits the separation of the DC power from the AC power and their reconstruction, for use in conventional AC-only and DC-only devices.

  15. Drilling history core hole DC-8

    International Nuclear Information System (INIS)

    1978-10-01

    Core hole DC-8 was completed in August, 1978 by Boyles Brothers Drilling Company, Spokane, Washington, under subcontract to Fenix and Scission, Inc. The hole was cored for the US Department of Energy and the Rockwell Hanford Operations' Basalt Waste Isolation Program. Fenix and Scisson, Inc. furnished the engineering, daily supervision of the core drilling activities, and geologic core logging for hole DC-8. Core hole DC-8 is located on the Hanford Site near the Wye Barricade and 50 feet northwest of rotary hole DC-7. The Hanford Site vation coordinates for DC-8 are North 14,955.94 feet and West 14,861.92 coordinates for DC-8 are North 14,955.94 feet and West 14,861.92 mean sea level. The purpose of core hole DC-8 was to core drill vertically through the basalt and interbed units for stratigraphic depth determination and core collection, and to provide a borehole for hydrologic testing and cross-hole seismic shear and pressure wave velocity studies with rotary hole DC-7. The total depth of core hole DC-8 was 4100.5 feet. Core recovery exceeded 97 percent of the total footage cored

  16. Drilling history core hole DC-8

    Energy Technology Data Exchange (ETDEWEB)

    1978-10-01

    Core hole DC-8 was completed in August, 1978 by Boyles Brothers Drilling Company, Spokane, Washington, under subcontract to Fenix and Scission, Inc. The hole was cored for the US Department of Energy and the Rockwell Hanford Operations' Basalt Waste Isolation Program. Fenix and Scisson, Inc. furnished the engineering, daily supervision of the core drilling activities, and geologic core logging for hole DC-8. Core hole DC-8 is located on the Hanford Site near the Wye Barricade and 50 feet northwest of rotary hole DC-7. The Hanford Site vation coordinates for DC-8 are North 14,955.94 feet and West 14,861.92 coordinates for DC-8 are North 14,955.94 feet and West 14,861.92 mean sea level. The purpose of core hole DC-8 was to core drill vertically through the basalt and interbed units for stratigraphic depth determination and core collection, and to provide a borehole for hydrologic testing and cross-hole seismic shear and pressure wave velocity studies with rotary hole DC-7. The total depth of core hole DC-8 was 4100.5 feet. Core recovery exceeded 97 percent of the total footage cored.

  17. Wide Temperature Range DC-DC Boost Converters for Command/Control/Drive Electronics, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — We shall develop wide temperature range DC-DC boost converters that can be fabricated using commercial CMOS foundries. The boost converters will increase the low...

  18. Modular Power System Configured with Standard Product Hybrid DC-DC Converters, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — VPT proposes an innovative concept whereby complex NASA space power electronic systems can be configured using a small number of qualified hybrid DC-DC converter and...

  19. Development of a DC-DC conversion powering scheme for the CMS Phase-1 pixel upgrade

    CERN Document Server

    Feld, Lutz Werner; Karpinski, Waclaw; Klein, Katja; Lipinski, Martin; Preuten, Marius; Max Rauch; Rittich, David Michael; Sammet, Jan Domenik; Wlochal, Michael

    2014-01-01

    A novel powering scheme based on the DC-DC conversion technique will be exploited to power the CMS Phase-1 pixel detector. DC-DC buck converters for the CMS pixel project have been developed, based on the AMIS5 ASIC designed by CERN. The powering system of the Phase-1 pixel detector is described and the performance of the converter prototypes is detailed, including power efficiency, stability of the output voltage, shielding, and thermal management. Results from a test of the magnetic field tolerance of the DC-DC converters are reported. System tests with pixel modules using many components of the future pixel barrel system are summarized. Finally first impressions from a pre-series of 200 DC-DC converters are presented.

  20. DIAGNOSTIC/PROGNOSTIC EXPERIMENTS FOR CAPACITOR DEGRADATION AND HEALTH MONITORING IN DC-DC CONVERTERS

    Data.gov (United States)

    National Aeronautics and Space Administration — Studying and analyzing the ageing mechanisms of electronic components avionics in systems such as the GPS and INAV are of critical importance. In DC-DC power...

  1. Digitally intensive DC-DC converter for extreme space environments, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The Space Micro –Arizona State University (ASU) team will develop an all-digitally controlled, wide temperature range point-of-load switch-mode DC-DC regulator core...

  2. Digitally intensive DC-DC converter for extreme space environments, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The Space Micro-Arizona State University (ASU) team will develop an all-digitally controlled, wide temperature range point-of-load switch-mode DC-DC regulator core...

  3. 75 FR 61352 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-10-30, DC-10-30F, DC-10-30F (KC...

    Science.gov (United States)

    2010-10-05

    ... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 10-30, DC-10-30F, DC-10-30F (KC-10A and KDC-10...-13 McDonnell Douglas Corporation: Amendment 39-16448; Docket No. FAA-2010-0553; Directorate.... Applicability (c) This AD applies to McDonnell Douglas Corporation Model DC- 10-30, DC-10-30F, DC-10-30F (KC-10A...

  4. 75 FR 27401 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-9-30, DC-9-40, and DC-9-50...

    Science.gov (United States)

    2010-05-17

    ... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 9-30, DC-9-40, and DC-9-50 Series Airplanes... airworthiness directive (AD) for certain Model DC-9-30, DC-9-40, and DC-9-50 series airplanes. This AD requires... this AD to detect and correct the potential for an arc/spark condition to occur within the fuel boost...

  5. Novel composite resonance DC-DC converter with voltage doubler rectifier

    OpenAIRE

    Kato, Hisatsugu; Matsuo, Hirohumi; Eguchi, Masaki; Sakamoto, Yukitaka; Nakaishi, Masaki

    2009-01-01

    This paper deals with a novel composite resonance DC-DC converter with the voltage doubler rectifier, which is developed to be applied to the power conditioner of the photovoltaic generation system. The proposed DC-DC converter has the current and voltage resonance functions. Therefore, the output voltage regulation can be achieved for the large variations of the input voltage and load. Also, this converter has the high power efficiency. The maximum power efficiency 96.1% can be realized.

  6. Regulation of DC development and DC-mediated T-cell immunity via CISH

    OpenAIRE

    Miah, Mohammad Alam; Bae, Yong-Soo

    2013-01-01

    Cytokine inducible SH2-containing protein (CISH) plays a crucial role in type 1 dendritic cell (DC) development as well as in the DC-mediated activation of cytotoxic T lymphocytes (CTLs). CISH expression at late DC developmental stages shuts down the proliferation of DC progenitors by negatively regulating signal transducer and activator of transcription 5 (STAT5) and facilitates the differentiation of DCs into potent stimulators of CTLs.

  7. Regulation of DC development and DC-mediated T-cell immunity via CISH.

    Science.gov (United States)

    Miah, Mohammad Alam; Bae, Yong-Soo

    2013-03-01

    Cytokine inducible SH2-containing protein (CISH) plays a crucial role in type 1 dendritic cell (DC) development as well as in the DC-mediated activation of cytotoxic T lymphocytes (CTLs). CISH expression at late DC developmental stages shuts down the proliferation of DC progenitors by negatively regulating signal transducer and activator of transcription 5 (STAT5) and facilitates the differentiation of DCs into potent stimulators of CTLs.

  8. Design and Analysis of Two-Phase Boost DC-DC Converter

    OpenAIRE

    Taufik Taufik; Tadeus Gunawan; Dale Dolan; Makbul Anwari

    2010-01-01

    Multiphasing of dc-dc converters has been known to give technical and economical benefits to low voltage high power buck regulator modules. A major advantage of multiphasing dc-dc converters is the improvement of input and output performances in the buck converter. From this aspect, a potential use would be in renewable energy where power quality plays an important factor. This paper presents the design of a 2-phase 200W boost converter for battery charging application. Analysis of results fr...

  9. A Fixed-Frequency Bidirectional Resonant DC-DC Converter Suitable for Wide Voltage Gain Range

    DEFF Research Database (Denmark)

    Shen, Yanfeng; Wang, Huai; Blaabjerg, Frede

    2017-01-01

    This paper proposes a new bidirectional resonant dc-dc converter suitable for wide voltage gain range applications (e.g., energy storage systems). The proposed converter overcomes the narrow voltage gain range of conventional resonant DC-DC converters, and meanwhile achieves high efficiency...... and characteristics of the proposed converter are analyzed. Finally, a 1-kW converter prototype is built and the experimental results verify the theoretical analyses....

  10. Development of a green mode DC/DC converter available to portable nuclear instrument

    International Nuclear Information System (INIS)

    Gao Feiyan; Wu Longxiong; Tan Wei; Tang Yaogeng

    2010-01-01

    A green mode DC/DC converter was developed which suitable to the portable nuclear instrument which is powered by battery and is sometime at stand-by mode. Some updated control approaches such as pseudo-resonant type power supply control and synchronous rectification were adopted to makethe DC/DC converter operate with low power consumption and high efficiency. The test results the battery can be prolonged with this converter. (authors)

  11. Superconducting dc fault current limiter

    International Nuclear Information System (INIS)

    Cointe, Y.

    2007-12-01

    Within the framework of the electric power market liberalization, DC networks have many interests compared to alternative ones, but their protections need to use new systems. Superconducting fault current limiters enable by an overstepping of the critical current to limit the fault current to a preset value, lower than the theoretical short-circuit current. For these applications, coated conductors offer excellent opportunities. We worked on the implementation of these materials and built a test bench. We carried out limiting experiments to estimate the quench homogeneity at various short-circuit parameters. An important point is the temperature measurement by deposited sensors on the ribbon, results are in good correlation with the theoretical models. Improved quench behaviours for temperatures close to the critical temperature have been confirmed. Our results enable to better understand the limitation mechanisms of coated conductors. (author)

  12. The possibility of detecting DC

    International Nuclear Information System (INIS)

    Witte, N.S.; Brown, R.D.

    1977-01-01

    IRC + 10216, a bright infrared late type carbon star, is observed to have millimetre range line emission of the species 12 CO, 13 CO, CS, C 2 H, HC 3 N, CN, HCN, SiS and SiO in an extended envelope around the central infrared sources. A model explaining the line emission in terms of infrared pumping between the two lowest vibrational levels, first proposed for IRC + 10216, was used to calculate antenna temperatures for various rotational transitions of HC 3 N; since there is a prima facie agreement between the calculated and observed values for HC 3 N we have attempted the same calculation for DC 3 N. (J.R.)

  13. Superconducting energy stabilizer with charging and discharging DC-DC converters

    International Nuclear Information System (INIS)

    Kim, S.H.; Kostecki, E.L.; DeWinkel, C.C.

    1992-01-01

    This patent describes a superconducting energy stabilizer having multiple load connections and employing DC-DC conversion for storing energy in a superconducting inductive energy storage device having a first end and a second end, and for releasing the stored energy from the superconducting inductive energy storage device to a load or loads or to a utility or an industrial electrical distribution system, the superconducting energy stabilizer having multiple load connections and employing DC-DC conversion. It comprises: energy storage cell means for supplying energy to the load, discharging DC-DC converter means for releasing energy from the superconducting inductive energy storage device to the energy storage cell means, the discharging DC-DC converter means having input terminals, output terminals, and a discharging control line means for carrying signals controlling the operation of the discharging DC-DC converter means, one of the input terminals of the discharging DC-DC converter means coupled to the first end of the superconducting energy storage device

  14. Dual wound dc brush motor gearhead

    Science.gov (United States)

    Henson, Barrie W.

    1986-01-01

    The design requirements, the design, development tests and problems, the qualification and life test and the findings of the strip examination of a dual wound DC brushed motor gearhead are described. It is the only space qualified dual wound dc brushed motor gearhead in Europe.

  15. Electronic DC transformer with high power density

    NARCIS (Netherlands)

    Pavlovský, M.

    2006-01-01

    This thesis is concerned with the possibilities of increasing the power density of high-power dc-dc converters with galvanic isolation. Three cornerstones for reaching high power densities are identified as: size reduction of passive components, reduction of losses particularly in active components

  16. DC/DC converters for integration of double-layer condensers in onboard power supply; DC/DC-Wandler zur Einbindung von Doppelschichtkondensatoren in das Fahrzeugenergiebordnetz

    Energy Technology Data Exchange (ETDEWEB)

    Polenov, Dieter

    2010-01-15

    The paper discusses DC/DC converters for integration of double layer condensers into the onboard power system. First, requirements on DC/DC converters are listed and compared on the basis of three exemplary applications. A DC/DC converter concept is developed for decoupling transient high-power loads like electric steering systems. Three different topologies are compared using a specially developed method in order to find the best solution for the given application. In order to establish adequate criteria for selecting the switching frequency and inductivities of storage throttles, the influence of the trottle power change on the switching characteristics of the MOSFETs and on certain ranges of EMP interference emissions is investigated. As methods of optimising the operation of the synchronous rectifiers, parallel connection of Schottky diodes and synchronous rectifiers as well as the variation of the shut-off dead times of synchronous rectifiers were investigated. Further, a concept for converter control was developed in consideration of the intended application and topology. Finally, selected aspects for implementation of the DC/DC converter concept are presented as well as the results of experimental investigations.

  17. Modelling of flow phenomena during DC casting

    NARCIS (Netherlands)

    Zuidema, J.

    2005-01-01

    Modelling of Flow Phenomena during DC Casting Jan Zuidema The production of aluminium ingots, by semi-continuous casting, is a complex process. DC Casting stands for direct chill casting. During this process liquid aluminium transforms to solid aluminium while cooling down. This is not an

  18. DC KIDS COUNT e-Databook Indicators

    Science.gov (United States)

    DC Action for Children, 2012

    2012-01-01

    This report presents indicators that are included in DC Action for Children's 2012 KIDS COUNT e-databook, their definitions and sources and the rationale for their selection. The indicators for DC KIDS COUNT represent a mix of traditional KIDS COUNT indicators of child well-being, such as the number of children living in poverty, and indicators of…

  19. Allelopathic effect of melissa, lemongrass, lavender and rosemary on germination and vigor of lettuce seeds

    Directory of Open Access Journals (Sweden)

    Daniela Aparecida Teixeira

    2014-12-01

    Full Text Available The objective of this study was to evaluate the influence of four herbal plants on the germination and vigor of lettuce seeds, using aqueous preparations and teas of Melissa oficinalis L. (melissa, Rosmarinus oficinalis L. (rosemary, Lavandula angustifolia Mill. (lavender and Cymbopogon citratus (DC. Stapf. (lemongrass. A randomized complete block design was used with 9 treatments and 4 repetitions. The treatments were: Melissa tea, melissa aqueous preparation, rosemary tea, rosemary aqueous preparation, lavender tea, lavender aqueous preparation, lemongrass tea, lemongrass aqueous preparation and control. The variables evaluated were: germination speed index, percentage of abnormal plants, percentage of germinated plants, fresh matter, dry matter, shoot length and radicle length. Lemongrass showed negative allelopathic effects on germination and vigor of L. sativa L. Melissa tea had a stimulatory effect.

  20. Allelopathic effect of melissa, lemongrass, lavender and rosemary on germination and vigor of lettuce seeds

    Directory of Open Access Journals (Sweden)

    Daniela Aparecida Teixeira

    2014-09-01

    Full Text Available http://dx.doi.org/10.5007/2175-7925.2014v27n4p37 The objective of this study was to evaluate the influence of four herbal plants on the germination and vigor of lettuce seeds, using aqueous preparations and teas of Melissa officinalis L. (melissa, Rosmarinus officinalis L. (rosemary, Lavandula angustifolia Mill. (lavender and Cymbopogon citratus (DC. Stapf. (lemongrass. A randomized complete block design was used with 9 treatments and 4 repetitions. The treatments were: melissa tea, melissa aqueous preparation, rosemary tea, rosemary aqueous preparation, lavender tea, lavender aqueous preparation, lemongrass tea, lemongrass aqueous preparation and control. The variables evaluated were: germination speed index, percentage of abnormal plants, percentage of germinated plants, fresh matter, dry matter, shoot length and radicle length. Lemongrass showed negative allelopathic effects on germination and vigor of L. sativa L. Melissa tea had a stimulatory effect.

  1. A Component-Reduced Zero-Voltage Switching Three-Level DC-DC Converter

    DEFF Research Database (Denmark)

    Qin, Zian; Pang, Ying; Wang, Huai

    2016-01-01

    The basic Zero-Voltage Switching (ZVS) three-level DC-DC converter has one clamping capacitor to realize the ZVS of the switches, and two clamping diodes to clamp the voltage of the clamping capacitor. In order to reduce the reverse recovery loss of the diode as well as its cost, this paper...... proposes to remove one of the clamping diodes in basic ZVS three-level DC-DC converter. With less components, the proposed converter can still have a stable clamping capacitor voltage, which is clamped at half of the dc link voltage. Moreover, the ZVS performance will be influenced by removing the clamping...

  2. Improved Control Strategy for T-type Isolated DC/DC Converters

    DEFF Research Database (Denmark)

    Liu, Dong; Deng, Fujin; Wang, Yanbo

    2017-01-01

    T-type isolated DC/DC converters have recently attracted attention due to their numerous advantages, including few components, low cost, and symmetrical operation of transformers. This study proposes an improved control strategy for increasing the efficiency of T-type isolated DC/DC converters....... Under the proposed strategy, the primary circulating current flows through the auxiliary switches (metal–oxide–semiconductor field-effect transistors) instead of their body diodes in free-wheeling periods. Such feature can reduce conduction losses, thereby improving the efficiency of T-type isolated DC...

  3. DC Voltage Droop Control Implementation in the AC/DC Power Flow Algorithm: Combinational Approach

    DEFF Research Database (Denmark)

    Akhter, F.; Macpherson, D.E.; Harrison, G.P.

    2015-01-01

    of operational flexibility, as more than one VSC station controls the DC link voltage of the MTDC system. This model enables the study of the effects of DC droop control on the power flows of the combined AC/DC system for steady state studies after VSC station outages or transient conditions without needing...... to use its complete dynamic model. Further, the proposed approach can be extended to include multiple AC and DC grids for combined AC/DC power flow analysis. The algorithm is implemented by modifying the MATPOWER based MATACDC program and the results shows that the algorithm works efficiently....

  4. Design of PI Controlled Non Isolated Bidirectional DC to DC Converter for Electric Vehicle Application

    Science.gov (United States)

    Geetha, A.; Subramani, C.; Thamizh Thentral, T. M.; Krithika, V.; Usha, S.

    2018-04-01

    Non isolated Bidirectional DC-DC Converter (NIBDDC) is a good interface between DC source and inverter Fed induction motor drive. This paper deals with comparison between open loop and PI controlled Bidirectional DC to DC Converter Inverter System (BDDCIS). The modelling and control of BDDC is becomes an important issue. Open loop BDDCIS and closed loop PI controlled BDDCIS are designed, modelled and simulated using Matlab- simulink and their results are presented. The investigations indicate superior performance of PI controlled BDDCIS. The proposed BDDCIS has advantages like bidirectional power transfer ability, reduced hardware count and improved dynamic response.

  5. Drilling history core hole DC-4

    International Nuclear Information System (INIS)

    1978-12-01

    Core hole DC-4 was completed at a depth of 3998 feet in December, 1978 by Boyles Brothers Drilling Company, Spokane, Washington, under subcontract to Fenix and Scission, Inc. The hole was cored for the US Department of Energy and the Rockwell Hanford Operations' Basalt Waste Isolation Program. Fenix and Sicsson, Inc. furnished the engineering, daily supervision of the cable tool and core drilling activities, and geological core logging for DC-4. Core hole DC-4 is located on the Hanford Site about 3 miles east of the Yakima Barricade and approximately 103 feet southwest of rotary hole DC-5, which was completed to 3990 feet in February, 1978. Hanford Site coordinates reported for hole DC-4 are north 49,385.62 feet and west 85,207.63 feet, and Washington State coordinates are north 454,468.73 feet and east 2,209,990.87 feet. No elevation survey is available for hole DC-4, but it is approximately 745 feet above mean sea level based upon the survey of hole DC-5, which has a reported elevation of 745.16 feet on the top of the 3-inch flange. The purpose of core hole DC-4 was to core drill vertically through the basalt and interbed units for stratigraphic depth determination and core collection, and to provide a borehole for hydrologic testing, cross-hole seismic shear, and pressure wave velocity studies with rotary hole DC-5. Hole DC-4 was drilled through the overburden into basalt bedrock by cable tool methods (0-623 feet) and continuously cored through the final interval (623 to 3998 feet).Core recovery was 95.8 percent of the total footage cored

  6. Controlling DC-DC converters by chaos-based pulse width modulation to reduce EMI

    International Nuclear Information System (INIS)

    Li Hong; Zhang Bo; Li Zhong; Halang, Wolfgang A.; Chen Guanrong

    2009-01-01

    In this paper, periodic and chaotic behaviors of DC-DC converters under certain parametric conditions are simulated, experimentally verified, and analyzed. Motivated by the work of J.H.B. Deane and D.C. Hamill in 1996, where chaotic phenomena are useful in suppressing electromagnetic interference (EMI) by adjusting the parameters of the DC-DC converter and making it operate in chaos, a chaos-based pulse width modulation (CPWM) is proposed to distribute the harmonics of the DC-DC converters continuously and evenly over a wide frequency range, thereby reducing the EMI. The output waves and spectral properties of the EMI are simulated and analyzed as the carrier frequency or amplitude changes with regard to different chaotic maps. Simulation and experimental results are given to illustrate the effectiveness of the proposed CPWM, which provides a good example of applying chaos theory in engineering practice.

  7. A Dual-Buck–Boost AC/DC Converter for DC Nanogrid With Three Terminal Outputs

    DEFF Research Database (Denmark)

    Wu, Weimin; Wang, Houqing; Liu, Yuan

    2017-01-01

    Due to the widely used dc characterized loads and more distributed power generation sources, the dc nanogrid becomes more and more popular, and it is seen as an alternative to the ac grid. For safety considerations, the dc nanogrid should provide reliable grounding for the residential loads...... such as the low-voltage ac power system. There are three typical grounding configurations for a dc nanogrid: the united grounding, the unidirectional grounding, and the virtual isolated grounding. Each grounding configuration has its own specifications to ac/dc converters. In this paper, a dual-buck-boost ac/dc...... converter for use in the united-grounding-configuration-based dc nanogrid with three terminal outputs is proposed. The working principle of this converter is presented in detail through analyzing the equivalent circuits. Experiments are carried out to verify the theoretical analysis....

  8. A high voltage ratio and low ripple interleaved DC-DC converter for fuel cell applications.

    Science.gov (United States)

    Chang, Long-Yi; Chao, Kuei-Hsiang; Chang, Tsang-Chih

    2012-01-01

    This paper proposes a high voltage ratio and low ripple interleaved boost DC-DC converter, which can be used to reduce the output voltage ripple. This converter transfers the low DC voltage of fuel cell to high DC voltage in DC link. The structure of the converter is parallel with two voltage-doubler boost converters by interleaving their output voltages to reduce the voltage ripple ratio. Besides, it can lower the current stress for the switches and inductors in the system. First, the PSIM software was used to establish a proton exchange membrane fuel cell and a converter circuit model. The simulated and measured results of the fuel cell output characteristic curve are made to verify the correctness of the established simulation model. In addition, some experimental results are made to validate the effectiveness in improving output voltage ripple of the proposed high voltage ratio interleaved boost DC-DC converters.

  9. Improved DC Gun Insulator Assembly

    International Nuclear Information System (INIS)

    Neubauer, M.L.; Dudas, A.; Sah, R.; Poelker, M.; Surles-Law, K.E.L.

    2010-01-01

    Many user facilities such as synchrotron radiation light sources and free electron lasers require accelerating structures that support electric fields of 10-100 MV/m, especially at the start of the accelerator chain where ceramic insulators are used for very high gradient DC guns. These insulators are difficult to manufacture, require long commissioning times, and often exhibit poor reliability. Two technical approaches to solving this problem will be investigated. Firstly, inverted ceramics offer solutions for reduced gradients between the electrodes and ground. An inverted design will be presented for 350 kV, with maximum gradients in the range of 5-10 MV/m. Secondly, novel ceramic manufacturing processes will be studied, in order to protect triple junction locations from emission, by applying a coating with a bulk resistivity. The processes for creating this coating will be optimized to provide protection as well as be used to coat a ceramic with an appropriate gradient in bulk resistivity from the vacuum side to the air side of an HV standoff ceramic cylinder. Example insulator designs are being computer modelled, and insulator samples are being manufactured and tested

  10. Investigations of dc breakdown fields

    CERN Document Server

    Ramsvik, Trond; Reginelli, Alessandra; Taborelli, Mauro

    2006-01-01

    The need for high accelerating gradients for the future 30 GHz multi-TeV e+e- Compact Linear Collider (CLIC) at CERN has triggered a comprehensive study of DC breakdown fields of metals in UHV. The study shows that molybdenum (Mo), tungsten (W), titanium (Ti) and TiVAl reach high breakdown fields, and are thus good candidates for the iris material of CLIC structures. A significant decrease in the saturated breakdown field (Esat) is observed for molybdenum and tungsten when exposed to air. Specifically, at air pressures of 10-5 mbar, the decrease in Esat is found to be 50% and 30% for molybdenum and tungsten, respectively. In addition, a 30% decrease is found when molybdenum is conditioned with a CO pressure of ~1-10-5 mbar. Surface analysis measurements and breakdown conditioning in O2 ambience imply that the origin of the decrease in Esat is closely linked to oxide formation on the cathode surface. "Ex-situ" treatments by ion bombardment of molybdenum effectively reduce the oxide layers, and improve the brea...

  11. A THREE-PHASE BOOST DC-AC CONVERTER

    African Journals Online (AJOL)

    dc-ac converter (inverter) based on the dc-dc boost converters. ... Sliding mode controllers are designed to perform a robust control for the ... Computer simulations and spectral analysis demon- ... the conventional three-phase buck inverter,.

  12. 75 FR 75872 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-9-30, DC-9-40, and DC-9-50...

    Science.gov (United States)

    2010-12-07

    ... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 9-30, DC-9-40, and DC-9-50 Series Airplanes...: We are adopting a new airworthiness directive (AD) for the McDonnell Douglas Corporation airplanes... to include an airworthiness directive (AD) that would apply to certain McDonnell Douglas Model DC-9...

  13. Pulsed-DC selfsputtering of copper

    International Nuclear Information System (INIS)

    Wiatrowski, A; Posadowski, W M; Radzimski, Z J

    2008-01-01

    At standard magnetron sputtering conditions (argon pressure ∼0.5 Pa) inert gas particles are often entrapped in the formed films. Inert gas contamination can be eliminated by using the self-sustained magnetron sputtering process because it is done in the absence of the inert gas atmosphere. The self-sustained sputtering (SSS) gives also a unique condition during the transport of sputtered particles to the substrate. It is especially useful for filling high aspect ratio submicron scale structures for microelectronics. So far it has been shown that the self-sputtering process can be sustained in the DC operation mode (DC-SSS) only. The main disadvantage of DC-SSS process is instability related to possible arc formation. Usage of pulsed sputtering, similarly to reactive pulsed magnetron sputtering, could eliminate this problem. In this paper results of pulsed-DC self-sustained magnetron sputtering (pulsed DC-SSS) of copper are presented for the first time. The planar magnetron equipped with a 50 mm in diameter and 6 mm thick copper target was powered by DC-power supply modulated by power switch. The maximum target power was about 11 kW (∼550W/cm 2 ). The magnetron operation was investigated as a function of pulsing frequency (20-100 kHz) and duty factor (50-90%). The discharge extinction pressure was determined for these conditions. The plasma emission spectra (400-410nm range) and deposition rates were observed for both DC and pulsed DC sustained self-sputtering processes. The presented results illustrate that stable pulsed DC-SSS process can be obtained at pulsing frequency in the range of 60-100 kHz and duty factor of 70-90%

  14. Pulsed-DC selfsputtering of copper

    Science.gov (United States)

    Wiatrowski, A.; Posadowski, W. M.; Radzimski, Z. J.

    2008-03-01

    At standard magnetron sputtering conditions (argon pressure ~0.5 Pa) inert gas particles are often entrapped in the formed films. Inert gas contamination can be eliminated by using the self-sustained magnetron sputtering process because it is done in the absence of the inert gas atmosphere. The self-sustained sputtering (SSS) gives also a unique condition during the transport of sputtered particles to the substrate. It is especially useful for filling high aspect ratio submicron scale structures for microelectronics. So far it has been shown that the self-sputtering process can be sustained in the DC operation mode (DC-SSS) only. The main disadvantage of DC-SSS process is instability related to possible arc formation. Usage of pulsed sputtering, similarly to reactive pulsed magnetron sputtering, could eliminate this problem. In this paper results of pulsed-DC self-sustained magnetron sputtering (pulsed DC-SSS) of copper are presented for the first time. The planar magnetron equipped with a 50 mm in diameter and 6 mm thick copper target was powered by DC-power supply modulated by power switch. The maximum target power was about 11 kW (~550W/cm2). The magnetron operation was investigated as a function of pulsing frequency (20-100 kHz) and duty factor (50-90%). The discharge extinction pressure was determined for these conditions. The plasma emission spectra (400-410nm range) and deposition rates were observed for both DC and pulsed DC sustained self-sputtering processes. The presented results illustrate that stable pulsed DC-SSS process can be obtained at pulsing frequency in the range of 60-100 kHz and duty factor of 70-90%.

  15. Superconducting DC homopolar motors for ship propulsion

    Energy Technology Data Exchange (ETDEWEB)

    Heiberger, M.; Reed, M.R.; Creedon, W.P.; O' Hea, B.J. [General Atomic (United States)

    2000-07-01

    Superconducting DC homopolar motors have undergone recent advances in technology, warranting serious consideration of their use for ship propulsion. Homopolar motor propulsion is now practical because of two key technology developments: cryogen-free superconducting refrigeration and high performance motor fiber brushes. These compact motors are ideal for podded applications, where reduced drag and fuel consumption are predicted. In addition, the simple DC motor controller is more efficient and reliable compared with AC motor controllers. Military ships also benefit from increased stealth implicit in homopolar DC excitation, which also allows the option for direct hull or pod mounting. (authors)

  16. DC-Compensated Current Transformer †

    Science.gov (United States)

    Ripka, Pavel; Draxler, Karel; Styblíková, Renata

    2016-01-01

    Instrument current transformers (CTs) measure AC currents. The DC component in the measured current can saturate the transformer and cause gross error. We use fluxgate detection and digital feedback compensation of the DC flux to suppress the overall error to 0.15%. This concept can be used not only for high-end CTs with a nanocrystalline core, but it also works for low-cost CTs with FeSi cores. The method described here allows simultaneous measurements of the DC current component. PMID:26805830

  17. High power density dc/dc converter: Selection of converter topology

    Science.gov (United States)

    Divan, Deepakraj M.

    1990-01-01

    The work involved in the identification and selection of a suitable converter topology is described. Three new dc/dc converter topologies are proposed: Phase-Shifted Single Active Bridge DC/DC Converter; Single Phase Dual Active Bridges DC/DC Converter; and Three Phase Dual Active Bridges DC/DC Converter (Topology C). The salient features of these topologies are: (1) All are minimal in structure, i.e., each consists of an input and output bridge, input and output filter and a transformer, all components essential for a high power dc/dc conversion process; (2) All devices of both the bridges can operate under near zero-voltage conditions, making possible a reduction of device switching losses and hence, an increase in switching frequency; (3) All circuits operate at a constant frequency, thus simplifying the task of the magnetic and filter elements; (4) Since, the leakage inductance of the transformer is used as the main current transfer element, problems associated with the diode reverse recovery are eliminated. Also, this mode of operation allows easy paralleling of multiple modules for extending the power capacity of the system; (5) All circuits are least sensitive to parasitic impedances, infact the parasitics are efficently utilized; and (6) The soft switching transitions, result in low electromagnetic interference. A detailed analysis of each topology was carried out. Based on the analysis, the various device and component ratings for each topology operating at an optimum point, and under the given specifications, are tabulated and discussed.

  18. CISH is induced during DC development and regulates DC-mediated CTL activation.

    Science.gov (United States)

    Miah, Mohammad Alam; Yoon, Cheol-Hee; Kim, Joonoh; Jang, Jinah; Seong, Young-Rim; Bae, Yong-Soo

    2012-01-01

    The cytokine inducible SH2-domain protein (CISH) is a well-known STAT5 target gene, but its role in the immune system remains uncertain. In this study, we found that CISH is predominantly induced during dendritic cell (DC) development from mouse bone marrow (BM) cells and plays a crucial role in type 1 DC development and DC-mediated CTL activation. CISH knockdown reduced the expression of MHC class I, co-stimulatory molecules and pro-inflammatory cytokines in BMDCs. Meanwhile, the DC yield was markedly enhanced by CISH knockdown via cell-cycle activation and reduction of cell apoptosis. Down-regulation of cell proliferation at the later stage of DC development was found to be associated with CISH-mediated negative feedback regulation of STAT5 activation. In T-cell immunity, OT-1 T-cell proliferation was significantly reduced by CISH knockdown in DCs, whereas OT-2 T-cell proliferation was not affected by CISH knockdown. CTLs generated by DC vaccination were also markedly reduced by CISH knockdown, followed by significant impairment of DC-based tumor immunotherapy. Taken together, our data suggest that CISH expression at the later stage of DC development triggers the shutdown of DC progenitor cell proliferation and facilitates DC differentiation into a potent stimulator of CTLs. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Study on the Control Algorithm of Two-Stage DC-DC Converter for Electric Vehicles

    Directory of Open Access Journals (Sweden)

    Changhao Piao

    2014-01-01

    Full Text Available The fast response, high efficiency, and good reliability are very important characteristics to electric vehicles (EVs dc/dc converters. Two-stage dc-dc converter is a kind of dc-dc topologies that can offer those characteristics to EVs. Presently, nonlinear control is an active area of research in the field of the control algorithm of dc-dc converters. However, very few papers research on two-stage converter for EVs. In this paper, a fixed switching frequency sliding mode (FSFSM controller and double-integral sliding mode (DISM controller for two-stage dc-dc converter are proposed. And a conventional linear control (lag is chosen as the comparison. The performances of the proposed FSFSM controller are compared with those obtained by the lag controller. In consequence, the satisfactory simulation and experiment results show that the FSFSM controller is capable of offering good large-signal operations with fast dynamical responses to the converter. At last, some other simulation results are presented to prove that the DISM controller is a promising method for the converter to eliminate the steady-state error.

  20. Studi Komparasi Fungsi Keanggotaan Fuzzy sebagai Kontroler Bidirectional DC-DC Converter pada Sistem Penyimpan Energi

    Directory of Open Access Journals (Sweden)

    Eka Prasetyono

    2015-09-01

    Full Text Available Bidirectional DC-DC converter is needed in the energy storage system. The converter topology used in this paper was a non-isolated bidirectional DC-DC buck-boost converter. This converter worked in two ways, which the charging mode stored energy into battery when load current was less than nominal main DC current (set point and discharging mode transferred energy from battery to the load when its current exceeded set point value. Both of these modes worked automatically according to the load current. The charging and discharging currents were controlled by fuzzy logic controller which was implemented on microcontroller ARM Cortex-M4F STM32F407VG. This paper compares two types of fuzzy membership function (triangular and sigmoid in controlling bidirectional DC-DC converter. The results showed that fuzzy logic controller with triangle membership function and sigmoid as control bidirectional DC-DC converter had no significant different response, both had an average error for charging and discharging process under 4% with ripple current on the main DC bus around 0.5%. The computing time of program for fuzzy logic controller with triangular membership functions had 19.01% faster than sigmoid, and fuzzy logic computation time on a microcontroller with hardware floating point was 60% faster than software floating point.

  1. NAMMA DC-8 DROPSONDE V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The DC-8 dropsonde system uses an integrated, highly accurate, GPS-located atmospheric profiling dropsonde, which measures and records current atmospheric conditions...

  2. dc power system for deuteron accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Creek, K.O.; Liska, D.J.

    1981-01-01

    The Fusion Materials Irradiation Test (FMIT) Facility dc power system provides excitation current for all linac and High-Energy Beam Transport (HEBT) quadrupole and bending magnets, excitation for horizontal and vertical beam steering, and current-bypass shunts.

  3. Determination of input/output characteristics of full-bridge AC/DC/DC converter for arc welding

    OpenAIRE

    Stefanov, Goce; Karadzinov, Ljupco; Sarac, Vasilija; Cingoski, Vlatko; Gelev, Saso

    2016-01-01

    This paper describes the design and practical implementation of AC/DC/DC converter in mode of arc welding. An analysis of the operation of AC/DC/DC converter and its input/output characteristics are determined with computer simulations. The practical part is consisted of AC/DC/DC converter prototype for arc welding with output power of 3 kW and switching frequency of 64 kHz. The operation of AC/DC/DC converter is validated with experimental measurements.

  4. Ultra-high Efficiency DC-DC Converter using GaN Devices

    DEFF Research Database (Denmark)

    Ramachandran, Rakesh

    2016-01-01

    properties of GaN devices can be utilized in power converters to make them more compact and highly efficient. This thesis entitled “Ultra-high Efficiency DC-DC Converter using GaN devices” focuses on achieving ultra-high conversion efficiency in an isolated dc-dc converter by the optimal utilization of Ga...... for many decades. However, the rate of improvement slowed as the silicon power materials asymptotically approached its theoretical bounds. Compared to Si, wideband gap materials such as Silicon Carbide (SiC) and Gallium Nitride (GaN) are promising semiconductors for power devices due to their superior...... in this thesis. Efficiency measurements from the hardware prototype of both the topologies are also presented in this thesis. Finally, the bidirectional operation of an optimized isolated dc-dc converter is presented. The optimized converter has achieved an ultra-high efficiency of 98.8% in both directions...

  5. Modeling, Analysis and Control of Different DC-DC Converter Topologies for Photo Voltaic Emulator

    Directory of Open Access Journals (Sweden)

    Mohammad Tauquir Iqbal

    2016-05-01

    Full Text Available This paper presents the modeling, analysis and control of different DC-DC converter topologies to emulate the photovoltaic (PV system. A PV emulator is basically a DC-DC converter having same electrical characteristics that of solar PV panel.  The emulator helps to achieve real characteristics of PV system in a better way in an environment where using actual PV systems can produce inconsistent results due to variation in weather conditions. The paper describes different types of DC-DC converters like buck, Resonant and Quasi Resonant Converter. The complete system is modelled in MATLAB® Simulink SimPowerSystem software package. The Simulation results obtained from the MATLAB® Simulink SimPowerSystem software package for different topologies under steady and dynamic conditions are analyzed and presented. An evaluation table is also presented at the end of the paper, presenting the effectiveness of each topology.

  6. Application handbook for a Standardized Control Module (SCM) for DC-DC converters, volume 1

    Science.gov (United States)

    Lee, F. C.; Mahmoud, M. F.; Yu, Y.

    1980-01-01

    The standardized control module (SCM) was developed for application in the buck, boost and buck/boost DC-DC converters. The SCM used multiple feedback loops to provide improved input line and output load regulation, stable feedback control system, good dynamic transient response and adaptive compensation of the control loop for changes in open loop gain and output filter time constraints. The necessary modeling and analysis tools to aid the design engineer in the application of the SCM to DC-DC Converters were developed. The SCM functional block diagram and the different analysis techniques were examined. The average time domain analysis technique was chosen as the basic analytical tool. The power stage transfer functions were developed for the buck, boost and buck/boost converters. The analog signal and digital signal processor transfer functions were developed for the three DC-DC Converter types using the constant on time, constant off time and constant frequency control laws.

  7. Application handbook for a Standardized Control Module (SCM) for DC-DC converters, volume 1

    Science.gov (United States)

    Lee, F. C.; Mahmoud, M. F.; Yu, Y.

    1980-04-01

    The standardized control module (SCM) was developed for application in the buck, boost and buck/boost DC-DC converters. The SCM used multiple feedback loops to provide improved input line and output load regulation, stable feedback control system, good dynamic transient response and adaptive compensation of the control loop for changes in open loop gain and output filter time constraints. The necessary modeling and analysis tools to aid the design engineer in the application of the SCM to DC-DC Converters were developed. The SCM functional block diagram and the different analysis techniques were examined. The average time domain analysis technique was chosen as the basic analytical tool. The power stage transfer functions were developed for the buck, boost and buck/boost converters. The analog signal and digital signal processor transfer functions were developed for the three DC-DC Converter types using the constant on time, constant off time and constant frequency control laws.

  8. Test Results of Selected Commercial DC/DC Converters under Cryogenic Temperatures - A Digest

    Science.gov (United States)

    Patterson, Richard; Hammoud, Ahmad

    2010-01-01

    DC/DC converters are widely used in space power systems in the areas of power management and distribution, signal conditioning, and motor control. Design of DC/DC converters to survive cryogenic temperatures will improve the power system performance, simplify design, and reduce development and launch costs. In this work, the performance of nine COTS modular, low-tomedium power DC/DC converters was investigated under cryogenic temperatures. The converters were evaluated in terms of their output regulation, efficiency, and input and output currents. At a given temperature, these properties were obtained at various input voltages and at different load levels. A summary on the performance of the tested converters was given. More comprehensive testing and in-depth analysis of performance under long-term exposure to extreme temperatures are deemed necessary to establish the suitability of these and other devices for use in the harsh environment of space exploration missions.

  9. Precharge strategies for isolated modular DC-DC converters under two different start-up conditions

    DEFF Research Database (Denmark)

    Zhang, Yi; Wang, Huai; Li, Binbin

    2017-01-01

    The isolated modular DC-DC converter (IMDCC) is a new topology designed to connect high-voltage direct current (HVDC) lines with different voltage levels, which ties two DC grids by using two modular multilevel converters (MMCs) via a medium-frequency transformer. Due to the large value of capaci......The isolated modular DC-DC converter (IMDCC) is a new topology designed to connect high-voltage direct current (HVDC) lines with different voltage levels, which ties two DC grids by using two modular multilevel converters (MMCs) via a medium-frequency transformer. Due to the large value...... of capacitance in the IMDCC, proper precharge strategies before the start-up are significant for the safety and reliability of the whole system. This paper presents two closed-loop precharge control strategies to fully charge the sub-module (SM) capacitors of the IMDCC, considering two different start...

  10. Biochemical parameters of Spodoptera frugiperda (J. E. Smith) treated with citronella oil (Cymbopogon winterianus Jowitt ex Bor) and its influence on reproduction.

    Science.gov (United States)

    Silva, Cristiane Thalita Dos Santos; Wanderley-Teixeira, Valéria; Cunha, Franklin Magliano da; Oliveira, José Vargas de; Dutra, Kamilla de Andrade; Navarro, Daniela Maria do Amaral Ferraz; Teixeira, Álvaro Aguiar Coelho

    2016-05-01

    Spodoptera frugiperda is the principal corn pest in Brazil. Searches for new control methods that minimize the adverse effects of synthetic insecticides have initiated a resurgence of the use of botanical insecticides. Citronella oil (a product of Cymbopogon winterianus) is an effective repellent and insecticide. Thus, biochemical profile changes in oil-treated larvae and its influence on reproduction were assessed. Corn leaves dipped in a 50mg/mL concentration were offered to third instar larvae for 24h and assessed in sixth instar to estimate protein, lipid, sugar, and glycogen levels. Adult testes and ovarioles were collected for histological and histochemical analysis 24h after emergence. Number of eggs and hatching rate were also measured. Oil-treated larvae showed an increase in glycogen and a decrease in protein, lipid, and totals sugar content. Control testes exhibited connective tissue lining and cysts with abundant spermatozoids. However, intense peripheral vacuolation and neutral carbohydrates reduction occurred in oil-treated individuals. Control ovarioles showed normal morphologic characteristics. On the other hand, oil-treatment ovarioles showed follicular cell stratification and removal, reduced nurse cell development, reduced yolk quantity, a thinner conjunctiva sheath, and a reduction in proteins and neutral carbohydrates. Eggs derived from oil-treated pairs were unviable. Therefore, sub-lethal doses of citronella oil alters the biochemical profile of S. frugiperda larvae, causing damage to their reproductive histophysiology and results in diminished reproduction or reproductive failure. Copyright © 2016 Elsevier GmbH. All rights reserved.

  11. Kingsnorth-London dc transmission link

    Energy Technology Data Exchange (ETDEWEB)

    1966-03-11

    The hvdc transmission link between one of the 500 MW generators at Kingsnorth Power Station and two receiving stations in London will use a three-wire dc cable system rated to carry 1200 A at +- 266 kV. This 51-mile system will be the first dc link in the world to be used as an integral part of a complex interconnected ac network.

  12. Hole history, rotary hole DC-3

    International Nuclear Information System (INIS)

    1977-10-01

    Purpose of hole DC-3 was to drill into the Umtanum basalt flow using both conventional rotary and core drilling methods. The borehole is to be utilized for geophysical logging, future hydrological testing, and the future installation of a borehole laboratory for long-term pressure, seismic, and moisture migration or accumulation recording in the Umtanum basalt flow in support of the Basalt Waste Isolation Program. Hole DC-3 is located east of the 200 West barricaded area on the Hanford reservation

  13. DC-8 MTP calibration for SOLVE-2

    Science.gov (United States)

    Mahoney, M. J.

    2003-01-01

    The Jet Propulsion Laboratory (JPL) Microwave Temperature Profiler (MTP) was the only instrument making temperature measurements at and below flight level on the DC-8 during the SOLVE-2 campaign. Many years of careful comparison of MTP measurements with radiosondes near the DC-8 flight track have shown that the flight level temperature can be determined to an accuracy of 0.2K relative to radiosondes.

  14. dc illusion and its experimental verification

    Science.gov (United States)

    Liu, Min; Lei Mei, Zhong; Ma, Xiang; Cui, Tie Jun

    2012-07-01

    Based on the transformation optics method, we propose a dc illusion device, which can transform a metallic object into a magnified dielectric object using anisotropic conducting materials. Utilizing the analogy between electric conductivities and resistor networks, we design and fabricate the device using metal film resistors. The practical measurement data agree very well with simulation results. The proposed dc illusion device is easy to process and measure, and thus has potential applications in various sectors.

  15. Characterization of diode valve in medium voltage dc/dc converter for wind turbines

    DEFF Research Database (Denmark)

    Dincan, Catalin Gabriel; Kjær, Philip Carne

    2016-01-01

    This paper proposes a methodology for characterization of medium voltage (MV), medium frequency (MF) rectifier diode valve. The intended application is for 10MW dc/dc converters used in DC offshore wind turbines. Sensitivity to semiconductor component parameter variation, snubber component tolera...... tolerance, influence of temperature and stray capacitance are analyzed. It is concluded that the largest impact on sensitivity is given by reverse recovery charge variation and differences of temperature between adjacent devices....

  16. Computer Simulation of Phase Shifted Series Resonant DC to DC Converter

    Directory of Open Access Journals (Sweden)

    P. PARVATHY

    2016-01-01

    Full Text Available This paper deals with digital simulation of phase shifted series resonant DC to DC converter using Matlab Simulink. The Simulink models for open loop and closed loop systems are developed and they are used for simulation studies. This converter is capable of producing ripple free DC output. Switching losses and switching stresses are reduced by using soft switching. This converter has advantages like high power density and low switching losses. Theoretical predictions are well supported by the simulation results.

  17. DC-Link Compensation Method for Slim DC Link Drives Fed by Soft Grid

    DEFF Research Database (Denmark)

    Mathe, Laszlo; Rosendahl Andersen, Henrik; Lazar, Radu

    2010-01-01

    Slim DC-link PWM (AC) drives for lowperformance applications are emerging on the market. Such drives equipped with a small DC-link capacitance exhibit instability tendencies, if installed on a soft line, giving a degraded performance. The total harmonic distortion (THD) and the partially weighted...... harmonic distortion (PWHD) of the line current are degraded, if resonance between the line impedance and the DC-link capacitance occurs. Likewise, the motor performance is affected negatively giving extra torque ripple, vibration and acoustic-noise emission. This paper proposes a novel DC-link compensation...

  18. Egr2 induced during DC development acts as an intrinsic negative regulator of DC immunogenicity.

    Science.gov (United States)

    Miah, Mohammad Alam; Byeon, Se Eun; Ahmed, Md Selim; Yoon, Cheol-Hee; Ha, Sang-Jun; Bae, Yong-Soo

    2013-09-01

    Early growth response gene 2 (Egr2), which encodes a zinc finger transcription factor, is rapidly and transiently induced in various cell types independently of de novo protein synthesis. Although a role for Egr2 is well established in T-cell development, Egr2 expression and its biological function in dendritic cells (DCs) have not yet been described. Here, we demonstrate Egr2 expression during DC development, and its role in DC-mediated immune responses. Egr2 is expressed in the later stage of DC development from BM precursor cells. Even at steady state, Egr2 is highly expressed in mouse splenic DCs. Egr2-knockdown (Egr2-KD) DCs showed increased levels of major histocompatability complex (MHC) class I and II and co-stimulatory molecules, and enhanced antigen uptake and migratory capacities. Furthermore, Egr2-KD abolished SOCS1 expression and signal transducer and activator of transcription 5 (STAT5) activation during DC development, probably resulting in the enhancement of IL-12 expression and Th1 immunogenicity of a DC vaccine. DC-mediated cytotoxic T lymphocyte (CTL) activation and antitumor immunity were significantly enhanced by Egr2-KD, and impaired by Egr2 overexpression in antigen-pulsed DC vaccines. These data suggest that Egr2 acts as an intrinsic negative regulator of DC immunogenicity and can be an attractive molecular target for DC vaccine development. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Analysis of high voltage step-up nonisolated DC-DC boost converters

    Science.gov (United States)

    Alisson Alencar Freitas, Antônio; Lessa Tofoli, Fernando; Junior, Edilson Mineiro Sá; Daher, Sergio; Antunes, Fernando Luiz Marcelo

    2016-05-01

    A high voltage step-up nonisolated DC-DC converter based on coupled inductors suitable to photovoltaic (PV) systems applications is proposed in this paper. Considering that numerous approaches exist to extend the voltage conversion ratio of DC-DC converters that do not use transformers, a detailed comparison is also presented among the proposed converter and other popular topologies such as the conventional boost converter and the quadratic boost converter. The qualitative analysis of the coupled-inductor-based topology is developed so that a design procedure can be obtained, from which an experimental prototype is implemented to validate the theoretical assumptions.

  20. High-Voltage DC-DC Converter Topology for PV Energy Utilization - Investigation and Implementation

    DEFF Research Database (Denmark)

    Sanjeevikumar, Padmanaban; Blaabjerg, Frede; Wheeler, Patrick

    2017-01-01

    This paper exploited the utilization of photovoltaic (PV) energy system with high-voltage (HV) output DC-DC converter. Classical boost converters are used for both renewable energy integration and HV applications, but limited by reducing output/efficiency in performance. Moreover, as parasitic...... elements suppress the power transfer ratio, converter needs to maximize the PV energy utilization. This investigation study focused to include additional parasitic elements (voltage-lift technique) to a standard DC-DC buck converter and to overcome all the above drawbacks to maximize the PV power...

  1. Digital peak current mode control with adaptive slope compensation for DC-DC converters

    DEFF Research Database (Denmark)

    Andersen, Karsten Holm; Nymand, Morten

    2017-01-01

    performance and stability of current mode control. The presented method adapt to DC-DC converter operating conditions by estimating the rising and falling inductor current slopes, to apply a current slope compensation value to obtain a constant quality factor. The experimental results verifies the theoretical......This paper presents an adaptive slope compensation method for peak current mode control of digital controlled DC-DC converters, which controls the quality factor of the complex conjugated poles at half the switching frequency. Using quality factor control enables optimization of the dynamic...

  2. A Novel PPFHB Bidirectional DC-DC Converter for Supercapacitor Application

    DEFF Research Database (Denmark)

    Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael Andreas E.

    2009-01-01

    This paper presents a novel bidirectional DC-DC converter for the supercapacitor application. In the proposed converter, push-pull forward with half bridge (PPFHB) voltage doubler structure is used to reduce the number of the power switches and get higher voltage gain. Based on phase-shift modula......This paper presents a novel bidirectional DC-DC converter for the supercapacitor application. In the proposed converter, push-pull forward with half bridge (PPFHB) voltage doubler structure is used to reduce the number of the power switches and get higher voltage gain. Based on phase...

  3. The application of standardized control and interface circuits to three dc to dc power converters.

    Science.gov (United States)

    Yu, Y.; Biess, J. J.; Schoenfeld, A. D.; Lalli, V. R.

    1973-01-01

    Standardized control and interface circuits were applied to the three most commonly used dc to dc converters: the buck-boost converter, the series-switching buck regulator, and the pulse-modulated parallel inverter. The two-loop ASDTIC regulation control concept was implemented by using a common analog control signal processor and a novel digital control signal processor. This resulted in control circuit standardization and superior static and dynamic performance of the three dc-to-dc converters. Power components stress control, through active peak current limiting and recovery of switching losses, was applied to enhance reliability and converter efficiency.

  4. Laboratory manual for pulse-width modulated DC-DC power converters

    CERN Document Server

    Kazimierczuk, Marian K

    2015-01-01

    Designed to complement a range of power electronics study resources, this unique lab manual helps students to gain a deep understanding of the operation, modeling, analysis, design, and performance of pulse-width modulated (PWM) DC-DC power converters.  Exercises focus on three essential areas of power electronics: open-loop power stages; small-signal modeling, design of feedback loops and PWM DC-DC converter control schemes; and semiconductor devices such as silicon, silicon carbide and gallium nitride. Meeting the standards required by industrial employers, the lab manual combines program

  5. A Bidirectional Multi-Port DC-DC Converter Integrating Voltage Equalizer

    DEFF Research Database (Denmark)

    Chen, Jianfei; Hou, Shiying; Deng, Fujin

    2015-01-01

    A novel bidirectional multi-port dc-dc converter integrating voltage equalizer based on switched-capacitor voltage accumulator (SCVA) is proposed. It has two operating modes of charging and discharging for battery modules. All battery modules are connected in series indirectly and can be equalize...... battery modules with different voltages. Simulation results has shown the feasibility of the proposed converter.......A novel bidirectional multi-port dc-dc converter integrating voltage equalizer based on switched-capacitor voltage accumulator (SCVA) is proposed. It has two operating modes of charging and discharging for battery modules. All battery modules are connected in series indirectly and can be equalized...

  6. A Bidirectional Resonant DC-DC Converter Suitable for Wide Voltage Gain Range

    DEFF Research Database (Denmark)

    Shen, Yanfeng; Wang, Huai; Al-Durra, Ahmed

    2018-01-01

    This paper proposes a new bidirectional resonant dc-dc converter suitable for wide voltage gain range applications (e.g., energy storage systems). The proposed converter overcomes the narrow voltage gain range of conventional resonant dc-dc converters, and meanwhile achieves high efficiency...... losses. The operation principles and characteristics of the proposed converter are firstly analyzed in this paper. Then the analytical solutions for the voltage gain, soft-switching, and rms currents are derived, which facilitates the parameters design and optimization. Finally, the proposed topology...... and analysis are verified with experimental results obtained from a 1-kW converter prototype....

  7. Design of the DC-DC power stage of the capacitor charger for MAXIDISCAP power converters

    CERN Document Server

    Cravero, Jean-Marc

    2013-01-01

    This technical report presents the design of the DC-DC power stage of the capacitor charger for MAXIDISCAP power converters. The power stage is based on a half bridge series resonant converter in Discontinuous Conduction Mode (DCM). This simple and robust topology allows obtaining a current source behavior with a low switching losses power stage. The associated control stage is implemented using a commercial controller which has differenti nternal circuits that allows a high integration of the converter control system. The report presents the design and tuning criteria for the DC-DC converter, including the power stage and the control system.

  8. Analysis and Design of Bi-Directional DC-DC Converter in the Extended Run Time DC UPS System Based on Fuel Cell and Supercapacitor

    DEFF Research Database (Denmark)

    Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.

    2009-01-01

    Abstract-In this paper, an extended run time DC UPS system structure with fuel cell and supercapacitor is investigated. A wide input range bi-directional dc-dc converter is described along with the phase-shift modulation scheme and phase-shift with duty cycle control, in different modes. The deli......Abstract-In this paper, an extended run time DC UPS system structure with fuel cell and supercapacitor is investigated. A wide input range bi-directional dc-dc converter is described along with the phase-shift modulation scheme and phase-shift with duty cycle control, in different modes...

  9. Impact of Faults and Protection Methods on DC Microgrids Operation

    DEFF Research Database (Denmark)

    Bayati, Navid; Hajizadeh, Amin; N. Soltani, Mohsen

    2018-01-01

    with the DC Microgrid. This paper evaluates and presents a comprehensive review on the most recent studies in the DC Microgrids protection. Moreover, the fault behavior and characteristics of DC Microgrids, the effect of Constant Power Load (CPL) , and recent DC Microgrid protection methods are reviewed. Also...

  10. Producción de biomasa verde y calidad de aceites esenciales de palmarosa (Cymbopogon martini Roxb.) con aplicación de fertilizantes de síntesis y orgánicos

    OpenAIRE

    Javier Alberto Pinzón-Torres; Nelson Jovany Contreras Porras; Diego Camilo Durán García; Jairo René Martínez Morales; Elena Stashenko

    2014-01-01

    El uso de fertilizantes minerales en cultivos de Cymbopogon martini Roxb. (Palmarosa) con el fin de incrementar la biomasa y el rendimiento de aceite esencial (AE) es una práctica cada vez más frecuente. Este aceite es rico en geraniol y acetato de geranilo, moléculas con alto valor en las industrias de productos cosméticos y farmacéutica. Las plantas fueron obtenidas del Centro Nacional de Investigación Agroindustrial de Plantas Aromaticas y Medicinales de la Universidad Industrial de Santan...

  11. Zero-voltage DC/DC converter with asymmetric pulse-width modulation for DC micro-grid system

    Science.gov (United States)

    Lin, Bor-Ren

    2018-04-01

    This paper presents a zero-voltage switching DC/DC converter for DC micro-grid system applications. The proposed circuit includes three half-bridge circuit cells connected in primary-series and secondary-parallel in order to lessen the voltage rating of power switches and current rating of rectifier diodes. Thus, low voltage stress of power MOSFETs can be adopted for high-voltage input applications with high switching frequency operation. In order to achieve low switching losses and high circuit efficiency, asymmetric pulse-width modulation is used to turn on power switches at zero voltage. Flying capacitors are used between each circuit cell to automatically balance input split voltages. Therefore, the voltage stress of each power switch is limited at Vin/3. Finally, a prototype is constructed and experiments are provided to demonstrate the circuit performance.

  12. Ultrahigh-density trench cpacitors in silicon and their application to integrated DC-DC conversion

    NARCIS (Netherlands)

    Roozeboom, F.; Bergveld, H.J.; Nowak, K.; Le Cornec, F.; Guiraud, L.; Bunel, C.; Iochem, S.; Ferreira, J.; Ledain, S.; Pieraerts, E.; Pommier, M.

    2009-01-01

    This paper addresses silicon-based integration of passive components applied to 3D integration with dies of other technologies within one package. Particularly, the development of high-density trench capacitors has enabled the realization of small-formfactor DC-DC converters. As illustration, an

  13. Reliability study of high gain DC-DC converters based on RRPP I-IIA ...

    Indian Academy of Sciences (India)

    J DIVYA NAVAMANI

    2018-05-10

    May 10, 2018 ... Energy Storage Modules (ESM), Propulsion Motor Mod- ules (PMM) and ... All Electric Ship (AES) is the best way to power all the loads in the ship ... also used to derive quadratic step down DC-DC converters. [6]. The attractive ...... Exhibition on Ecological Vehicles and Renewable Energies,. TamilNadu ...

  14. Investigation of DC-DC Boost Converter for Reliability of Operational Planning

    DEFF Research Database (Denmark)

    Khazraj, Hesam; Ashouri, Mani; Silva, Filipe Miguel Faria da

    2018-01-01

    of the interests related to reliability is the power semiconductor switches, which are the most vulnerable elements. The failure of one-power switches can reduce the system reliability. Interleaved technique for DC-DC converters is a redundant strategy to improve the reliability, but at the cost of increasing...

  15. A New Sliding Mode Controller for DC/DC Converters in Photovoltaic Systems

    Directory of Open Access Journals (Sweden)

    M. Sarvi

    2013-01-01

    Full Text Available DC/DC converters are widely used in many industrial and electrical systems. As DC/DC converters are nonlinear and time-variant systems, the application of linear control techniques for the control of these converters is not suitable. In this paper, a new sliding mode controller is proposed as the indirect control method and compared to a simple direct control method in order to control a buck converter in photovoltaic applications. The solar arrays are dependent power sources with nonlinear voltage-current characteristics under different environmental conditions (insolation and temperature. From this point of view, the DC/DC converter is particularly suitable for the application of the sliding mode control in photovoltaic application, because of its controllable states. Simulations are performed in Matlab/Simulink software. The simulation results are presented for a step change in reference voltage and input voltage as well as step load variations. The simulations results of proposed method are compared with the conventional PID controller. The results show the good performance of the proposed sliding mode controller. The proposed method can be used for the other DC/DC converter.

  16. Switched capacitor DC-DC converter with switch conductance modulation and Pesudo-fixed frequency control

    DEFF Research Database (Denmark)

    Larsen, Dennis Øland; Vinter, Martin; Jørgensen, Ivan Harald Holger

    A switched capacitor dc-dc converter with frequency-planned control is presented. By splitting the output stage switches in eight segments the output voltage can be regulated with a combination of switching frequency and switch conductance. This allows for switching at predetermined frequencies, 31...

  17. Spectral shaping of a randomized PWM DC-DC converter using maximum entropy probability distributions

    CSIR Research Space (South Africa)

    Dove, Albert

    2017-01-01

    Full Text Available maintaining constraints in a DC-DC converter is investigated. A probability distribution whose aim is to ensure maximal harmonic spreading and yet mainaint constraints is presented. The PDFs are determined from a direct application of the method of Maximum...

  18. Common mode noise in three-level DC-DC converters

    CSIR Research Space (South Africa)

    Grobler, Inus

    2009-09-01

    Full Text Available that three-level buck DC-DC converters in general generate much lower common mode currents than conventional two-level buck converters. Further, reductions in common mode currents are achieved by using the improved three-level topologies that have been...

  19. Y-Source Boost DC/DC Converter for Distributed Generation

    DEFF Research Database (Denmark)

    Siwakoti, Yam P.; Loh, Poh Chiang; Blaabjerg, Frede

    2015-01-01

    This paper introduces a versatile Y-source boost dc/dc converter intended for distributed power generation, where high gain is often demanded. The proposed converter uses a Y-source impedance network realized with a tightly coupled three-winding inductor for high voltage boosting that is presently...

  20. Experimental study of dynamic behaviors and routes to chaos in DC-DC boost converters

    International Nuclear Information System (INIS)

    Cafagna, D.; Grassi, G.

    2005-01-01

    This paper illustrates an experimental study of a current-programmed DC-DC boost converter, with the aim of investigating possible pathways through which the converter may enter chaos. In particular, based on experimental measurements, it is shown that variations of input voltage and reference current can generate periodic, subharmonic, quasi-periodic and chaotic behaviors

  1. Magnetically integrated high step-up resonant DC-DC converter for distributed photovoltaic systems

    DEFF Research Database (Denmark)

    Vinnikov, Dmitri; Chub, Andrii; Liivik, Elizaveta

    2017-01-01

    In this paper magnetically integrated resonant single-switch quasi-Z-source DC-DC converter is evaluated as a candidate topology for the low-cost photovoltaic microconverter. The derivation of the topology and its basic operation principle are explained. Generalized design guidelines...

  2. Quasiperiodicity and Torus Breakdown in a Power Electronic DC/DC Converter

    DEFF Research Database (Denmark)

    Zhusubaliyev, Zhanybai; Soukhoterin, Evgeniy; Mosekilde, Erik

    2007-01-01

    This paper discusses the mechanisms of torus formation and torus destruction in a dc/dc converter with relay control and hysteresis. We establish a chart of the dynamical modes in the input voltage versus load resistance parameter plane. This chart displays several different torus bifurcations...

  3. A DC-DC Converter with Wide Input Voltage Range for Fuel Cell and Supercapacitor Application

    DEFF Research Database (Denmark)

    Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael Andreas E.

    2009-01-01

    This paper proposes a novel phase-shift plus duty cycle controlled hybrid bi-directional DC-DC converter based on fuel cells and supercapacitors. The described converter employs two high frequency transformers to couple the half-bridge and full-bridge circuits together in the primary side...

  4. Modelling, Simulation and Construction of a DC/DC Boost Power Converter: A School Experimental System

    Science.gov (United States)

    Silva-Ortigoza, R.; Silva-Ortigoza, G.; Hernandez-Guzman, V. M.; Saldana-Gonzalez, G.; Marcelino-Aranda, M.; Marciano-Melchor, M.

    2012-01-01

    We introduce a dc/dc boost power converter as a didactic prototype intended to support courses on electric circuit analysis experimentally. The corresponding mathematical model is obtained, the converter is designed and an experimental setup is described, constructed and tested. Simplicity of construction as well as low cost of components renders…

  5. High-power three-port three-phase bidirectional DC-DC converter

    NARCIS (Netherlands)

    Tao, H.; Duarte, J.L.; Hendrix, M.A.M.

    2007-01-01

    This paper proposes a three-port three-phase bidirectional dc-dc converter suitable for high-power applications. The converter combines a slow primary source and a fast storage to power a common load (e.g., an inverter). Since this type of system is gaining popularity in sustainable energy

  6. Floating high step-down stacked dc-dc converter based on buck-boost cells

    NARCIS (Netherlands)

    Tibola, G.; Duarte, J.L.; Blinov, A.

    2015-01-01

    In some high power dc-dc applications, where high voltage is present, a converter with high step-down ratio is required in order to provide an isolated low power auxiliary supply. This requirement represents a challenge and many topologies are currently being researched. The analysis of a

  7. Magnetically coupled high-gain Y-source isolated DC/DC converter

    DEFF Research Database (Denmark)

    Siwakoti, Yam P.; Loh, Poh Chiang; Blaabjerg, Frede

    2014-01-01

    A new form of magnetically coupled DC/DC converter is proposed for medium power applications (250 W to 2 kW), requiring a high-voltage gain, short inductive charging time and galvanic isolation. The proposed converter can be realised using a unique Y-source impedance network and a two-switch push...

  8. Modelling, simulation and construction of a dc/dc boost power converter: a school experimental system

    International Nuclear Information System (INIS)

    Silva-Ortigoza, R; Marciano-Melchor, M; Silva-Ortigoza, G; Hernández-Guzmán, V M; Saldaña-González, G; Marcelino-Aranda, M

    2012-01-01

    We introduce a dc/dc boost power converter as a didactic prototype intended to support courses on electric circuit analysis experimentally. The corresponding mathematical model is obtained, the converter is designed and an experimental setup is described, constructed and tested. Simplicity of construction as well as low cost of components renders the feasible introduction of this equipment in undergraduate laboratories. (paper)

  9. Comparative evaluation of bidirectional dual active bridge DC-DC converter variants

    NARCIS (Netherlands)

    Sfakianakis, G.; Everts, J.; Huisman, H.; Lomonova, E.A.

    2016-01-01

    For the realization of DC-DC converters in automotive industry, the Dual Active Bridge (DAB) converter seems to be a promising choice because of its soft-switching and high-power-density capability. Contrary to the traditional 3 level - 3 level (3-3L) DAB, a 3 level - 5 level (3-5L) DAB can operate

  10. A Novel Single Switch Transformerless Quadratic DC/DC Buck-Boost Converter

    DEFF Research Database (Denmark)

    Mostaan, Ali; A. Gorji, Saman; N. Soltani, Mohsen

    2017-01-01

    A novel quadratic buck-boost DC/DC converter is presented in this study. The proposed converter utilizes only one active switch and can step-up/down the input voltage, while the existing single switch quadratic buck/boost converters can only work in step-up or step-down mode. First, the proposed ...

  11. Single Event Burnout in DC-DC Converters for the LHC Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Claudio H. Rivetta et al.

    2001-09-24

    High voltage transistors in DC-DC converters are prone to catastrophic Single Event Burnout in the LHC radiation environment. This paper presents a systematic methodology to analyze single event effects sensitivity in converters and proposes solutions based on de-rating input voltage and output current or voltage.

  12. Design and Implementation of Digital Current Mode Controller for DC-DC Converters

    DEFF Research Database (Denmark)

    Taeed, Fazel

    to be regulated by a closed-loop controller. The Peak Current Mode Control (PCMC) is one of the most promising control methods for dc-dc converters. It has been known for high bandwidth (speed), and inherent current protection. Increasing the controller bandwidth decreases the output filter size and cost. Analog...

  13. Selection of DC/DC converter for offshore wind farms with MVDC power collection

    DEFF Research Database (Denmark)

    Dincan, Catalin Gabriel; Kjær, Philip Carne; Chen, Yu-Hsing

    2017-01-01

    Four DC/DC converters are analyzed and compared with respects to availability, efficiency, ratings, repair costs and power density. Intended application is offshore wind farms with MVDC power collection. The selected topology is a new series resonant converter, which offers 99% efficiency across...

  14. Area-Efficiency Trade-Offs in Integrated Switched-Capacitor DC-DC Converters

    DEFF Research Database (Denmark)

    Spliid, Frederik Monrad; Larsen, Dennis Øland; Knott, Arnold

    2016-01-01

    This paper analyzes the relationship between efficiency and chip area in a fully integrated switched capacitor voltage divider dc-dc converter implemented in 180nm-technology and a 1/2 topology. A numerical algorithm for choosing the optimal sizes of individual components, in terms of power loss...

  15. Research on Two-channel Interleaved Two-stage Paralleled Buck DC-DC Converter for Plasma Cutting Power Supply

    DEFF Research Database (Denmark)

    Yang, Xi-jun; Qu, Hao; Yao, Chen

    2014-01-01

    As for high power plasma power supply, due to high efficiency and flexibility, multi-channel interleaved multi-stage paralleled Buck DC-DC Converter becomes the first choice. In the paper, two-channel interleaved two- stage paralleled Buck DC-DC Converter powered by three-phase AC power supply...

  16. Pulsed dc self-sustained magnetron sputtering

    International Nuclear Information System (INIS)

    Wiatrowski, A.; Posadowski, W. M.; Radzimski, Z. J.

    2008-01-01

    The magnetron sputtering has become one of the commonly used techniques for industrial deposition of thin films and coatings due to its simplicity and reliability. At standard magnetron sputtering conditions (argon pressure of ∼0.5 Pa) inert gas particles (necessary to sustain discharge) are often entrapped in the deposited films. Inert gas contamination can be eliminated during the self-sustained magnetron sputtering (SSS) process, where the presence of the inert gas is not a necessary requirement. Moreover the SSS process that is possible due to the high degree of ionization of the sputtered material also gives a unique condition during the transport of sputtered particles to the substrate. So far it has been shown that the self-sustained mode of magnetron operation can be obtained using dc powering (dc-SSS) only. The main disadvantage of the dc-SSS process is its instability related to random arc formation. In such case the discharge has to be temporarily extinguished to prevent damaging both the magnetron source and power supply. The authors postulate that pulsed powering could protect the SSS process against arcs, similarly to reactive pulsed magnetron deposition processes of insulating thin films. To put this concept into practice, (i) the high enough plasma density has to be achieved and (ii) the type of pulsed powering has to be chosen taking plasma dynamics into account. In this article results of pulsed dc self-sustained magnetron sputtering (pulsed dc-SSS) are presented. The planar magnetron equipped with a 50 mm diameter and 6 mm thick copper target was used during the experiments. The maximum target power was about 11 kW, which corresponded to the target power density of ∼560 W/cm 2 . The magnetron operation was investigated as a function of pulse frequency (20-100 kHz) and pulse duty factor (50%-90%). The discharge (argon) extinction pressure level was determined for these conditions. The plasma emission spectra (400-410 nm range) and deposition

  17. Modeling, Control and Protection of Low-Voltage DC Microgrids

    OpenAIRE

    Salomonsson, Daniel

    2008-01-01

    Current trends in electric power consumption indicate an increasing use of dc in end-user equipment, such as computers and other electronic appliances used in households and offices. With a dc power system, ac/dc conversion within these loads can be avoided, and losses reduced. AC/DC conversion is instead centralized, and by using efficient, fully controllable power-electronic interfaces, high power quality for both ac and dc systems during steady state and ac grid disturbances can be obtaine...

  18. Operation and control of a DC-grid offshore wind farm under DC transmission system faults

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2013-01-01

    . Consequently, the protection and control strategies of dc systems need to be established. This paper studies a dc-grid offshore wind farm, where the wind power collection system and power transmission system adopt dc technology. In this paper, the redundancy of the HVDC transmission system under faults...... is studied, and a fault ridethrough strategy for the dc-grid offshore wind farm is proposed. The proposed strategy can effectively minimize the impacts of the power transmission system disturbance on the offshore wind farm, and on the ac grid. A dc-grid offshore wind farm example is simulated with PSCAD....../EMTDC, and the results validate the feasibility of the presented redundancy configuration and operation approach, and the fault ridethrough control strategy....

  19. A suitable model plant for control of the set fuel cell-DC/DC converter

    Energy Technology Data Exchange (ETDEWEB)

    Andujar, J.M.; Segura, F.; Vasallo, M.J. [Departamento de Ingenieria Electronica, Sistemas Informaticos y Automatica, E.P.S. La Rabida, Universidad de Huelva, Ctra. Huelva - Palos de la Frontera, S/N, 21819 La Rabida - Palos de la Frontera Huelva (Spain)

    2008-04-15

    In this work a state and transfer function model of the set made up of a proton exchange membrane (PEM) fuel cell and a DC/DC converter is developed. The set is modelled as a plant controlled by the converter duty cycle. In addition to allow setting the plant operating point at any point of its characteristic curve (two interesting points are maximum efficiency and maximum power points), this approach also allows the connection of the fuel cell to other energy generation and storage devices, given that, as they all usually share a single DC bus, a thorough control of the interconnected devices is required. First, the state and transfer function models of the fuel cell and the converter are obtained. Then, both models are related in order to achieve the fuel cell+DC/DC converter set (plant) model. The results of the theoretical developments are validated by simulation on a real fuel cell model. (author)

  20. Analysis of DC/DC Converter Efficiency for Energy Storage System Based on Bidirectional Fuel Cells

    DEFF Research Database (Denmark)

    Pittini, Riccardo; Zhang, Zhe; Andersen, Michael A. E.

    2013-01-01

    interface to the grid. In power electronics, the converter efficiency is characterized at fixed operating voltage for various output power. This type of characterization is not suitable for fuel cells, since as the power from the fuel cell increases, the cell voltage decreases. This paper analyses how......Renewable energy sources are fluctuating depending on the availability of the energy source. For this reason, energy storage is becoming more important and bidirectional fuel cells represent an attractive technology. Fuel cells require highcurrent low-voltage dc-dc or dc-ac converters as power...... the fuel cell I-V characteristics influences the power electronics converter efficiency and their consequence on the overall system. A loaddependent efficiency curve is presented based on experimental results from a 6 kW dc-dc converter prototype including the most suitable control strategy which maximizes...

  1. Research borehole drilling activity for boreholes DH-18, DH-19, DC-12, DC-13, DC-14, DC-15, and deepening of existing borehole DC-7

    International Nuclear Information System (INIS)

    1979-09-01

    This report is an environmental evaluation of the impacts of proposed borehole drilling activities at the Hanford Site, northwest of Richland, Washington. The proposed action is to drill six research boreholes ranging in depth from 137 to 1372 meters (m) [250 to 4500 +- feet (ft)]. In addition, an existing borehole (DC-7) will be extended from 1249 to 1524 m (4099 to 5000 +- ft). The purpose of the US Department of Energy's (DOE) borehole drilling activities is to collect data on in situ rock formations that are considered potentialy suitable for nuclear waste repositories. The technical program efforts necessary to identify and qualify specific underground waste facility sites in candidate rock formations include geologic and hydrologic studies (seismicity and tectonics, rock structure and stratigraphy, lithology, etc.). Borehole drilling is an integral part of the geological studies and is essential to a thorough understanding of potentially suitable geologic formations. The purpose of the proposed drilling activities is to obtain data for evaluating Columbia River basalts that are being evaluated by the National Waste Terminal Storage (NWTS) Program to determine their suitability potential for nuclear waste repositories. Unavoidable impact to the environment is limited primarily to the clearing of land needed for access and drilling operations. Considerations exercised during site preparation, drilling, and subsequent site restoration will limit modification of the natural environment to the minimum required for accomplishment of test objectives

  2. Proliferating effect of radiolytically depolymerized carrageenan on physiological attributes, plant water relation parameters, essential oil production and active constituents of Cymbopogon flexuosus Steud. under drought stress.

    Science.gov (United States)

    Singh, Minu; Khan, M Masroor A; Uddin, Moin; Naeem, M; Qureshi, M Irfan

    2017-01-01

    Carrageenan has been proved as potent growth promoting substance in its depolymerized form. However, relatively little is known about its role in counteracting the adverse effects of drought stress on plants. In a pot experiment, lemongrass (Cymbopogon flexuosus Steud.), grown under different water stress regimes [(100% field capacity (FC), 80% FC and 60% FC)], was sprayed with 40, 80 and 120 mg L-1 of gamma irradiated carrageenan (ICA). Foliar application of ICA mitigated the harmful effects of drought stress to various extents and improved the biochemical characteristics, quality attributes and active constituents (citral and geraniol) of lemongrass significantly. Among the applied treatments, ICA-80 mg L-1 proved the best in alleviating detrimental effects of drought. However, drought stress (80 and 60% FC), irrespective of the growth stages, had an adverse impact on most of the studied attributes. Generally, 60% FC proved more deleterious than 80% FC. At 80% FC, application of ICA-80 mg L-1 elevated the essential oil (EO) content by 18.9 and 25%, citral content by 7.33 and 8.19% and geraniol content by 9.2 and 8.9% at 90 and 120 days after planting (DAP), respectively, as compared to the deionized-water (DW) spray treatment (80% FC+ DW). Whereas, at 60% FC, foliar application of 80 mg L-1 ICA significantly augmented the EO content by 15.4 and 17.8% and active constituents viz. citral and geraniol, by 5.01 and 5.62% and by 6.06 and 5.61% at 90 and 120 DAP, respectively, as compared to the control (water-spray treatment).

  3. Proliferating effect of radiolytically depolymerized carrageenan on physiological attributes, plant water relation parameters, essential oil production and active constituents of Cymbopogon flexuosus Steud. under drought stress.

    Directory of Open Access Journals (Sweden)

    Minu Singh

    Full Text Available Carrageenan has been proved as potent growth promoting substance in its depolymerized form. However, relatively little is known about its role in counteracting the adverse effects of drought stress on plants. In a pot experiment, lemongrass (Cymbopogon flexuosus Steud., grown under different water stress regimes [(100% field capacity (FC, 80% FC and 60% FC], was sprayed with 40, 80 and 120 mg L-1 of gamma irradiated carrageenan (ICA. Foliar application of ICA mitigated the harmful effects of drought stress to various extents and improved the biochemical characteristics, quality attributes and active constituents (citral and geraniol of lemongrass significantly. Among the applied treatments, ICA-80 mg L-1 proved the best in alleviating detrimental effects of drought. However, drought stress (80 and 60% FC, irrespective of the growth stages, had an adverse impact on most of the studied attributes. Generally, 60% FC proved more deleterious than 80% FC. At 80% FC, application of ICA-80 mg L-1 elevated the essential oil (EO content by 18.9 and 25%, citral content by 7.33 and 8.19% and geraniol content by 9.2 and 8.9% at 90 and 120 days after planting (DAP, respectively, as compared to the deionized-water (DW spray treatment (80% FC+ DW. Whereas, at 60% FC, foliar application of 80 mg L-1 ICA significantly augmented the EO content by 15.4 and 17.8% and active constituents viz. citral and geraniol, by 5.01 and 5.62% and by 6.06 and 5.61% at 90 and 120 DAP, respectively, as compared to the control (water-spray treatment.

  4. Geranyl acetate esterase controls and regulates the level of geraniol in lemongrass (Cymbopogon flexuosus Nees ex Steud.) mutant cv. GRL-1 leaves.

    Science.gov (United States)

    Ganjewala, Deepak; Luthra, Rajesh

    2009-01-01

    Essential oil isolated from lemongrass (Cymbopogon flexuosus) mutant cv. GRL-1 leaves is mainly composed of geraniol (G) and geranyl acetate (GA). The proportion of G and GA markedly fluctuates during leaf development. The proportions of GA and G in the essential oil recorded at day 10 after leaf emergence were approximately 59% and approximately 33% respectively. However, the level of GA went down from approximately 59 to approximately 3% whereas the level of G rose from approximately 33 to approximately 91% during the leaf growth period from day 10 to day 50. However, the decline in the level of GA was most pronounced in the early (day 10 to day 30) stage of leaf growth. The trend of changes in the proportion of GA and G has clearly indicated the role of an esterase that must be involved in the conversion of GA to G during leaf development. We isolated an esterase from leaves of different ages that converts GA into G and has been given the name geranyl acetate esterase (GAE). The GAE activity markedly varied during the leaf development cycle; it was closely correlated with the monoterpene (GA and G) composition throughout leaf development. GAE appeared as several isoenzymes but only three (GAE-I, GAE-II, and GAE-III) of them had significant GA cleaving activity. The GAE isoenzymes pattern was greatly influenced by the leaf developmental stages and so their GA cleaving activities. Like the GAE activity, GAE isoenzyme patterns were also found to be consistent with the monoterpene (GA and G) composition. GAE had an optimum pH at 8.5 and temperature at 30 degrees C. Besides GAE, a compound with phosphatase activity capable of hydrolyzing geranyl diphosphate (GPP) to produce geraniol has also been isolated.

  5. Three phase full wave dc motor decoder

    Science.gov (United States)

    Studer, P. A. (Inventor)

    1977-01-01

    A three phase decoder for dc motors is disclosed which employs an extremely simple six transistor circuit to derive six properly phased output signals for fullwave operation of dc motors. Six decoding transistors are coupled at their base-emitter junctions across a resistor network arranged in a delta configuration. Each point of the delta configuration is coupled to one of three position sensors which sense the rotational position of the motor. A second embodiment of the invention is disclosed in which photo-optical isolators are used in place of the decoding transistors.

  6. DCMF: DC & Microformats, a good marriage

    OpenAIRE

    Méndez Rodríguez, Eva María; Siches, Arnau; López, Leandro M.; Bravo, Alejandro G.

    2008-01-01

    This report introduces the Dublin Core Microformats (DCMF) project, a new way to use the DC element set within X/HTML. The DC microformats encode explicit semantic expressions in an X/HTML webpage, by using a specific list of terms for values of the attributes “rev” and “rel” for and elements, and “class” and “id” of other elements. Microformats can be easily processed by user agents and software, enabling a high level of interoperability. These characteristics are crucial for the growing n...

  7. Implementation of hierarchical control in DC microgrids

    DEFF Research Database (Denmark)

    Jin, Chi; Wang, Peng; Xiao, Jianfang

    2014-01-01

    of Technology, Singapore. The coordination control among multiple dc sources and energy storages is implemented using a novel hierarchical control technique. The bus voltage essentially acts as an indicator of supply-demand balance. A wireless control is implemented for the reliable operation of the grid....... A reasonable compromise between the maximum power harvest and effective battery management is further enhanced using the coordination control based on a central energy management system. The feasibility and effectiveness of the proposed control strategies have been tested by a dc microgrid in WERL....

  8. RF and dc desensitized electroexplosive device

    Science.gov (United States)

    Krainiak, John W.; Speaks, Paul D.; Cornett, Michael S.

    1989-07-01

    This patent application relates to electroexplosive devices (EEDs) such as detonators, blasting caps and squibs, in particular to a method and device for desensitizing EEDs to electromagnetic radiation and electrostatic charges with the added ability to desensitize the device to essentially dc currents. An insensitive electroexplosive device to electrically ignite explosive is disclosed. This device is inherently immune to radio frequency (RF) radiation, and also provides protection against dc or very low frequency RF induced by arcing. A central feature is use of zeners and capacitors to form a reactively balanced bridge circuit. When constructed in semiconductor form, as described in this application, the device is capable of incorporation in small caliber ordnance.

  9. DC Motor Drive with PFC Rectifier

    Directory of Open Access Journals (Sweden)

    Lascu Mihaela

    2008-05-01

    Full Text Available The goal of this work is to study theperformances of a hybrid controller used to controlDC Motor drive with a single-phase power factorcorrection rectifier. This study is made usingcomputer simulation (Simulink. The first part isdevoted to the control system of the DC Motors. Inthe second part, the design of the hybrid controllerwill be presented. The third part is the design ofthe fast response single-phase boost power factorcorrection rectifier. The last parts are devoted tosimulation and experimental results.

  10. Avaliação do teor e composição do óleo essencial de Cymbopogon nardus (L. em diferentes épocas de colheita Evaluation of content and composition of the essential oil of Cymbopogon nardus (L. in different harvest times

    Directory of Open Access Journals (Sweden)

    Henrique Guilhon de Castro

    2010-06-01

    Full Text Available Este trabalho objetivou analisar o teor e a composição do óleo essencial do Cymbopogon nardus, em cinco épocas de colheita no Estado do Tocantins. As colheitas foram realizadas em cinco épocas em intervalos regulares de 28 dias, sendo a primeira aos 56 dias e a última aos 168 dias após transplante. A extração do óleo essencial foi realizada por hidrodestilação e a identificação dos componentes por CG e CG/EM. Os maiores teores de óleo essencial foram obtidos na segunda época de colheita (1,10% e na última época de colheita (1,07%. Foram identificados vinte e três compostos químicos no óleo essencial. Os monoterpenos identificados foram: limoneno, linalol, isopulegol, citronelal, citronelol, neral, geraniol, acetato de citronelol e acetato de geraniol. Os sesquiterpenos identificados foram: beta-elemeno, germacreno, alfa-muroleno, gama-cadineno, delta-cadineno, elemol, germacreno D-4-OL, óxido de cariofileno, tau-cadinol, beta-eudesmol e alfa-eudesmol. Os compostos majoritários do óleo essencial foram o citronelol, o geraniol e o elemol.This study aimed to analyze the content and the composition of the essential oil of Cymbopogon nardus in five harvest times in Tocantins State. Five harvesting were carried out in regular space of 28 days, the first in 56 days and the last in 168 days after transplanting. The essential oil was obtained by hydro distillation and the identification of the oil components by GC and GC/MS. The highest contents of the essential oil were obtained in the second harvest time (1.15% and in the last harvest time (1.07%. Twenty three chemical compounds were identified in the essential oil. The monoterpenes identified were: limonene, linalool, isopulegol, citronellal, citronellol, neral, geraniol, citronellol acetate and geraniol acetate. The sesquiterpenes identified were: beta-elemene, germacrene, alpha-muurolene, gamma-cadinene, delta-cadinene, elemol, germacrene D-4-OL, caryophyllene oxide, tau

  11. Stability analysis of a high-step-Up DC grid-connected two-stage boost DC-DC converter

    Directory of Open Access Journals (Sweden)

    El Aroudi A.

    2014-01-01

    Full Text Available High conversion ratio switching converters are used whenever there is a need to step-up dc source voltage level to a much higher output dc voltage level such as in photovoltaic systems, telecommunications and in some medical applications. A simple solution for achieving this high conversion ratio is by cascading different stages of dc-dc boost converters. The individual converters in such a cascaded system are usually designed separately applying classical design criteria. However these criteria may not be applicable for the complete cascaded system . This paper first presents a glimpse on the bifurcation behavior that a cascade connection of two boost converters can exhibit. It is shown that the desired periodic orbit can undergo period doubling leading to subharmonic oscillations and chaotic regimes. Then, in order to simplify the analysis the second stage is considered as constant current sink and design-oriented analysis is carried out to obtain stability boundaries in the parameter space by taking into account slope interactions between the state variables in the two-different stages.

  12. Design and modelling of high gain DC-DC converters for fuel cell hybrid electric vehicles

    Science.gov (United States)

    Elangovan, D.; Karthigeyan, V.; Subhanu, B.; Ashwin, M.; Arunkumar, G.

    2017-11-01

    Transportation (Diesel and petrol internal combustion engine vehicles) approximately contributes to 25.5% of total CO2 emission. Thus diesel and petrol engine vehicles are the most dominant contributors of CO2 emission which leads global warming which causes climate change. The problem of CO2 emission and global warming can be reduced by focusing on renewable energy vehicles. Out of the available renewable energy sources fuel cell is the only source which has reasonable efficiency and can be used in vehicles. But the main disadvantage of fuel cell is its slow response time. So energy storage systems like batteries and super capacitors are used in parallel with the fuel cell. Fuel cell is used during steady state vehicle operation while during transient conditions like starting, acceleration and braking batteries and super capacitors can supply or absorb energy. In this paper a unidirectional fuel cell DC-DC converter and bidirectional energy storage system DC-DC converter is proposed, which can interface dc sources at different voltage levels to the dc bus and also it can independently control the power flow from each energy source to the dc bus and vice versa. The proposed converters are designed and simulated using PSIM version 9.1.1 and gate pulse pattern, input and output voltage waveforms of the converters for steady state operation are studied.

  13. Homopolar dc motor and trapped flux brushless dc motor using high temperature superconductor materials

    Science.gov (United States)

    Crapo, Alan D.; Lloyd, Jerry D.

    1991-03-01

    Two motors have been designed and built for use with high-temperature superconductor (HTSC) materials. They are a homopolar dc motor that uses HTSC field windings and a brushless dc motor that uses bulk HTSC materials to trap flux in steel rotor poles. The HTSC field windings of the homopolar dc motor are designed to operate at 1000 A/sq cm in a 0.010-T field. In order to maximize torque in the homopolar dc motor, an iron magnetic circuit with small air gaps gives maximum flux for minimum Ampere turns in the field. A copper field winding version of the homopolar dc motor has been tested while waiting for 575 A turn HTSC coils. The trapped flux brushless dc motor has been built and is ready to test melt textured bulk HTSC rings that are currently being prepared. The stator of the trapped flux motor will impress a magnetic field in the steel rotor poles with warm HTSC bulk rings. The rings are then cooled to 77 K to trap the flux in the rotor. The motor can then operate as a brushless dc motor.

  14. Comparison of solar panel cooling system by using dc brushless fan and dc water

    International Nuclear Information System (INIS)

    Irwan, Y M; Leow, W Z; Irwanto, M; M, Fareq; Hassan, S I S; Amelia, A R; Safwati, I

    2015-01-01

    The purpose of this article is to discuss comparison of solar panel cooling system by using DC brushless fan and DC water pump. Solar photovoltaic (PV) power generation is an interesting technique to reduce non-renewable energy consumption and as a renewable energy. The temperature of PV modules increases when it absorbs solar radiation, causing a decrease in efficiency. A solar cooling system is design, construct and experimentally researched within this work. To make an effort to cool the PV module, Direct Current (DC) brushless fan and DC water pump with inlet/outlet manifold are designed for constant air movement and water flow circulation at the back side and front side of PV module representatively. Temperature sensors were installed on the PV module to detect temperature of PV. PIC microcontroller was used to control the DC brushless fan and water pump for switch ON or OFF depend on the temperature of PV module automatically. The performance with and without cooling system are shown in this experiment. The PV module with DC water pump cooling system increase 3.52%, 36.27%, 38.98%in term of output voltage, output current, output power respectively. It decrease 6.36 °C compare than to PV module without DC water pump cooling system. While DC brushless fan cooling system increase 3.47%, 29.55%, 32.23%in term of output voltage, output current, and output power respectively. It decrease 6.1 °C compare than to PV module without DC brushless fan cooling system. The efficiency of PV module with cooling system was increasing compared to PV module without cooling system; this is because the ambient temperature dropped significantly. The higher efficiency of PV cell, the payback period of the system can be shorted and the lifespan of PV module can also be longer. (paper)

  15. Transition towards DC micro grids: From an AC to a hybrid AC and DC energy infrastructure

    Directory of Open Access Journals (Sweden)

    Evi Ploumpidou

    2017-12-01

    Full Text Available Our electricity is predominantly powered by alternating current (AC, ever since the War of Currents ended in the favor of Nicola Tesla at the end of the 19th century. However, lots of the appliances we use, such as electronics and lights with light-emitting diode (LED technology, work internally on direct current (DC and it is projected that the number of these appliances will increase in the near future. Another contributor to the increase in DC consumption is the ongoing electrification of mobility (Electric Vehicles (EVs. At the same time, photovoltaics (PV generate DC voltages, while the most common storage technologies also use DC. In order to integrate all these appliances and technologies to the existing AC grid, there is a need for converters which introduce power losses. By distributing DC power to DC devices instead of converting it to AC first, it is possible to avoid substantial energy losses that occur every time electricity is converted. This situation initiated the concept for the implementation of the DC-Flexhouse project. A prototype DC installation will be developed and tested in one of the buildings of the developing living lab area called the District of Tomorrow (De Wijk van Morgen which is located in Heerlen, the Netherlands. A neighborhood cooperative (Vrieheide cooperatie is also part of the consortium in order to address the aspect of social acceptance. Although DC seems to be a promising solution for a more sustainable energy system, the business case is still debatable due to both technology- and market-related challenges. The current energy infrastructure is predominantly based on AC, manufacturers produce devices based on AC standards and people are using many AC products across a long life span. This Smart Energy Buildings & Cities (SEB&C PDEng project is a contribution to the DC-Flexhouse project. The aim is to analyze the challenges in the transition to DC micro grids, assess the market potential of DC

  16. Properties of DLC coatings deposited by dc and dc with superimposed pulsed vacuum arc

    International Nuclear Information System (INIS)

    Zavaleyev, V.; Walkowicz, J.; Aksyonov, D.S.; Luchaninov, A.A.; Reshetnyak, E.N.; Strel'nitskij, V.E.

    2014-01-01

    Comparative studies of the structure, mechanical and tribological properties of DLC coatings deposited in DC and DC with superimposed high current pulse modes of operation vacuum-arc plasma source with the graphite cathode are presented. Imposition the pulses of high current on DC vacuum-arc discharge allows both increase the deposition rate of DLC coating and reduce the residual compressive stress in the coatings what promotes substantial improvement the adhesion to the substrate. Effect of vacuum arc plasma filtration with Venetian blind filter on the deposition rate and tribological characteristics of the coatings analyzed.

  17. Hierarchical Control for Multiple DC-Microgrids Clusters

    DEFF Research Database (Denmark)

    Shafiee, Qobad; Dragicevic, Tomislav; Vasquez, Juan Carlos

    2014-01-01

    DC microgrids (MGs) have gained research interest during the recent years because of many potential advantages as compared to the ac system. To ensure reliable operation of a low-voltage dc MG as well as its intelligent operation with the other DC MGs, a hierarchical control is proposed in this p......DC microgrids (MGs) have gained research interest during the recent years because of many potential advantages as compared to the ac system. To ensure reliable operation of a low-voltage dc MG as well as its intelligent operation with the other DC MGs, a hierarchical control is proposed...

  18. Modeling and simulation for micro DC motor based on simulink

    Science.gov (United States)

    Shen, Hanxin; Lei, Qiao; Chen, Wenxiang

    2017-09-01

    The micro DC motor has a large market demand but there is a lack of theoretical research for it. Through detailed analysis of the commutation process of micro DC motor commutator, based on micro DC motor electromagnetic torque equation and mechanical torque equation, with the help of Simulink toolkit, a triangle connection micro DC motor simulation model is established. By using the model, a sample micro DC motor are simulated, and an experimental measurements has been carried on the sample micro DC motor. It is found that the simulation results are consistent with theoretical analysis and experimental results.

  19. Power Quality in DC Power Distribution Systems and Microgrids

    Directory of Open Access Journals (Sweden)

    Stephen Whaite

    2015-05-01

    Full Text Available This review paper discusses power quality considerations for direct current (DC electric power distribution systems, particularly DC microgrids. First, four selected sample DC architectures are discussed to provide motivation for the consideration of power quality in DC systems. Second, a brief overview of power quality challenges in conventional alternating current (AC distribution systems is given to establish the field of power quality. Finally, a survey of literature addressing power quality issues in DC systems is presented, and necessary power quality considerations in DC distribution system design and operation are discussed.

  20. Halbach array DC motor/generator

    Science.gov (United States)

    Merritt, B.T.; Dreifuerst, G.R.; Post, R.F.

    1998-01-06

    A new configuration of DC motor/generator is based on a Halbach array of permanent magnets. This motor does not use ferrous materials so that the only losses are winding losses and losses due to bearings and windage. An ``inside-out`` design is used as compared to a conventional motor/generator design. The rotating portion, i.e., the rotor, is on the outside of the machine. The stationary portion, i.e., the stator, is formed by the inside of the machine. The rotor contains an array of permanent magnets that provide a uniform field. The windings of the motor are placed in or on the stator. The stator windings are then ``switched`` or ``commutated`` to provide a DC motor/generator much the same as in a conventional DC motor. The commutation can be performed by mechanical means using brushes or by electronic means using switching circuits. The invention is useful in electric vehicles and adjustable speed DC drives. 17 figs.

  1. Double-barrier junction based dc SQUID

    NARCIS (Netherlands)

    Bartolomé, M.E.; Brinkman, Alexander; Flokstra, Jakob; Golubov, Alexandre Avraamovitch; Rogalla, Horst

    2000-01-01

    dc SQUIDs based on double-barrier Nb/Al/AlOx/Al/AlOx/Al/Nb junctions (DBSQs) have been fabricated and tested for the first time. The current–voltage curves have been measured at temperatures down to 1.4 K. The critical current, Ic, dependence on the temperature T is partially described by the

  2. What should your DC default be?

    NARCIS (Netherlands)

    Cui, J.

    2009-01-01

    As reported, most DC pension scheme participants simply follow proposed defaults, even though they have the freedom to choose. Consequently, default designs have dramatic impacts on individuals’retirement saving outcomes. Given the fact that the default design matters, this paper evaluates

  3. Hierarchical Control for Multiple DC Microgrids Clusters

    DEFF Research Database (Denmark)

    Shafiee, Qobad; Dragicevic, Tomislav; Vasquez, Juan Carlos

    2014-01-01

    This paper presents a distributed hierarchical control framework to ensure reliable operation of dc Microgrid (MG) clusters. In this hierarchy, primary control is used to regulate the common bus voltage inside each MG locally. An adaptive droop method is proposed for this level which determines...

  4. Voltage control of DC islanded microgrids

    DEFF Research Database (Denmark)

    Tucci, Michele; Riverso, Stefano; Quintero, Juan Carlos Vasquez

    2015-01-01

    We propose a new decentralized control scheme for DC Islanded microGrids (ImGs) composed by several Distributed Generation Units (DGUs) with a general interconnection topology. Each local controller regulates to a reference value the voltage of the Point of Common Coupling (PCC...

  5. Halbach array DC motor/generator

    Science.gov (United States)

    Merritt, Bernard T.; Dreifuerst, Gary R.; Post, Richard F.

    1998-01-01

    A new configuration of DC motor/generator is based on a Halbach array of permanent magnets. This motor does not use ferrous materials so that the only losses are winding losses and losses due to bearings and windage. An "inside-out" design is used as compared to a conventional motor/generator design. The rotating portion, i.e., the rotor, is on the outside of the machine. The stationary portion, i.e., the stator, is formed by the inside of the machine. The rotor contains an array of permanent magnets that provide a uniform field. The windings of the motor are placed in or on the stator. The stator windings are then "switched" or "commutated" to provide a DC motor/generator much the same as in a conventional DC motor. The commutation can be performed by mechanical means using brushes or by electronic means using switching circuits. The invention is useful in electric vehicles and adjustable speed DC drives.

  6. Gravity Compensation Technique Uses Small dc Motor

    Science.gov (United States)

    Hollow, Richard

    1988-01-01

    Small dc servomotor powered by simple constant-current source and with suitable gearing used to cancel effect of gravity upon load. Lead-screw positioning system has load counterbalanced by small supplementary motor powered by constant current source. Motor lighter and more compact alternative to counterbalance. Used in variety of mechanical systems where load positioned or accelerated in vertical plane.

  7. Computerized Torque Control for Large dc Motors

    Science.gov (United States)

    Willett, Richard M.; Carroll, Michael J.; Geiger, Ronald V.

    1987-01-01

    Speed and torque ranges in generator mode extended. System of shunt resistors, electronic switches, and pulse-width modulation controls torque exerted by large, three-phase, electronically commutated dc motor. Particularly useful for motor operating in generator mode because it extends operating range to low torque and high speed.

  8. DC photoemission electron guns as ERL sources

    International Nuclear Information System (INIS)

    Sinclair, Charles K.

    2006-01-01

    Very-high-voltage DC electron guns, delivering moderate duration bunches from photoemission cathodes, and followed by conventional drift bunching and acceleration, offer a practical solution for an ERL injector. In a variant of this scheme, a DC gun is placed in close proximity to a superconducting RF accelerator cavity, with few or no active elements between the gun and cavity. The principal technical challenge with such electron guns arises from field emission from the cathode electrode and its support structure. Field emission may result in voltage breakdown across the cathode-anode gap, or a punch-through failure of the insulator holding off the cathode potential, as well as lesser though still serious problems. Various means to mitigate these problems are described. The operational lifetime of high quantum efficiency photocathodes in these guns is determined by the vacuum conditions, through phenomena such as chemical poisoning and ion back-bombardment. Minimization of the field strength on electrode structures pushes high-voltage DC guns toward large dimensions and, correspondingly, large outgassing loads, but it is also true that these guns offer many opportunities for achieving excellent vacuum conditions. Good solutions to vacuum problems that had previously limited cathode lifetime have been demonstrated in recent years. Designs for DC guns presently in use and planned for the near future will be described. The parameters necessary for a 100 mA average current, very-high-voltage DC gun with a photocathode operational lifetime greater than 100 h appear to be within reach, but have yet to be demonstrated. A 1 A average current source with good cathode operational lifetime will require developments beyond the present state-of-the-art

  9. Current Mode Control for LLC Series Resonant DC-to-DC Converters

    Directory of Open Access Journals (Sweden)

    Jinhaeng Jang

    2015-06-01

    Full Text Available Conventional voltage mode control only offers limited performance for LLC series resonant DC-to-DC converters experiencing wide variations in operational conditions. When the existing voltage mode control is employed, the closed-loop performance of the converter is directly affected by unavoidable changes in power stage dynamics. Thus, a specific control design optimized at one particular operating point could become unacceptable when the operational condition is varied. This paper presents a new current mode control scheme which could consistently provide good closed-loop performance for LLC resonant converters for the entire operational range. The proposed control scheme employs an additional feedback from the current of the resonant tank network to overcome the limitation of the existing voltage mode control. The superiority of the proposed current mode control over the conventional voltage mode control is verified using an experimental 150 W LLC series resonant DC-to-DC converter.

  10. DC-DC power converter research for Orbiter/Station power exchange

    Science.gov (United States)

    Ehsani, M.

    1993-01-01

    This project was to produce innovative DC-DC power converter concepts which are appropriate for the power exchange between the Orbiter and the Space Station Freedom (SSF). The new converters must interface three regulated power buses on SSF, which are at different voltages, with three fuel cell power buses on the Orbiter which can be at different voltages and should be tracked independently. Power exchange is to be bi-directional between the SSF and the Orbiter. The new converters must satisfy the above operational requirements with better weight, volume, efficiency, and reliability than is available from the present conventional technology. Two families of zero current DC-DC converters were developed and successfully adapted to this application. Most of the converters developed are new and are presented.

  11. Differential Mode EMI Filter Design for Isolated DC-DC Boost Converter

    DEFF Research Database (Denmark)

    Makda, Ishtiyaq Ahmed; Nymand, Morten

    2014-01-01

    A Differential Mode EMI filter for a low input voltage high-current isolated dc-dc boost converter is designed and presented in this paper. The primary side Differential Mode noise voltage is low due to the high transformer turn ratio, however, the input current is very high and since the EMI limit...... also does not change for such converters, it requires greatly optimized design approach for the filter including the correct sizing of the filter components. A complete analytical filter design process is carried out such a way that the Differential Mode noise voltage source in the converter...... is identified first. The DM noise model is then established and based on the harmonic analysis of the noise source voltage waveform, the complete Differential Mode EMI filter, including the filter resonance damping branch, is designed for a 3kW isolated dc-dc boost converter. The noise model and its theoretical...

  12. Multi-level cascaded DC/DC converters for PV applications

    Directory of Open Access Journals (Sweden)

    Ahmed A.A. Hafez

    2015-12-01

    Full Text Available A robust multi-level cascaded DC/DC system for Photovoltaic (PV application is advised in this article. There are three PV generators, each is coupled to a half-bridge buck cell. Each PV-generator–buck-converter channel is controlled such that maximum power is captured independently under different irradiation and temperature levels. The system operation under normal and abnormal conditions was comprehensively investigated. Internal Model Control (IMC technique was adopted for tuning the controllers. An elaborate switching modulation strategy was used to reduce the current ripple and inductor size, while maintaining high efficiency. Annotative, simple and robust remedial strategies were proposed to mitigate different anticipated faults. Comprehensive simulation results in Matlab environment were illustrated for corroborating the performance of the advised cascaded DC/DC system under normal/abnormal conditions. The proposed system enjoys the merits of independency, reduced volumetric dimensions and improved efficiency. Furthermore, the system is inherently fault-tolerant.

  13. High Voltage Coil Current Sensor for DC-DC Converters Employing DDCC

    Directory of Open Access Journals (Sweden)

    M. Drinovsky

    2015-12-01

    Full Text Available Current sensor is an integral part of every switching converter. It is used for over-current protection, regulation and in case of multiphase converters for balancing. A new high voltage current sensor for coil-based current sensing in DC-DC converters is presented. The sensor employs DDCC with high voltage input stage and gain trimming. The circuit has been simulated and implemented in 0.35 um BCD technology as part of a multiphase DC-DC converter where its function has been verified. The circuit is able to sustain common mode voltage on the input up to 40 V, it occupies 0.387*0.345 mm2 and consumes 3.2 mW typically.

  14. Analysis of the Coupling Behavior of PEM Fuel Cells and DC-DC Converters

    Directory of Open Access Journals (Sweden)

    Achim Kienle

    2009-03-01

    Full Text Available The connection between PEM fuel cells and common DC-DC converters is examined. The analysis is model-based and done for boost, buck and buck-boost converters. In a first step, the effect of the converter ripples upon the PEM fuel cell is shown. They introduce oscillations in the fuel cell. Their appearance is explained, discussed and possibilities for their suppression are given. After that, the overall behaviors of the coupled fuel cell-converter systems are analyzed. It is shown, that neither stationary multiplicities nor oscillations can be introduced by the couplings and therefore separate control approaches for both the PEMFC and the DC-DC converters are applicable.

  15. Integrated Three-Port DC-DC Converter for Photovoltaic (PV) Battery Stand-alone Systems

    DEFF Research Database (Denmark)

    Ouyang, Ziwei; Andersen, Michael A. E.

    2016-01-01

    of solar energy. Moreover, a novel transformer configuration enables variable turns ratio controlled by the phase between the two current excitations subjected to the primary windings, allowing a wider input/output range. 1 kW experimental prototype has been built to demonstrate a wellmanaged power flow......Several power sources such as PV solar arrays and battery are often used to manage the power flow for a photovoltaic (PV) based stand-alone power system due to the fluctuation nature of solar energy resource, and deliver a continuous power to the users in an appropriate form. Traditionally, three...... different single-input single-output (SISO) dc/dc converters would have been used. To reduce the cost and improve the power density of the system, an integrated three-port isolated dc/dc converter is proposed in this paper. It can realize all functions of the energy delivery due to the fluctuation nature...

  16. single-phase dc phase dc-ac boost converter ac boost converter

    African Journals Online (AJOL)

    User

    systems, need to step-up the DC input voltage. increase the ... design also makes for extra parts, greater system and weight, [1-3]. ... proposes a new design for high performance sin ... SYSTEM ANALYSIS. 2. ..... from the simulation study.

  17. Y-source impedance-network-based isolated boost DC/DC converter

    DEFF Research Database (Denmark)

    Siwakoti, Yam P.; Town, Graham; Loh, Poh Chiang

    2014-01-01

    A dc-dc converter with very high voltage gain is proposed in this paper for any medium-power application requiring a high voltage boost with galvanic isolation. The proposed converter topology can be realized using only two switches. With this topology a very high voltage boost can be achieved even...... with a relatively low duty cycle of the switches, and the gain obtainable is presently not matched by any existing impedance network based converter operated at the same duty ratio. The proposed converter has a Y-source impedance network to boost the voltage at the intermediate dc-link side and a push......-pull transformer for square-wave AC inversion and isolation. The voltage-doubler rectifier provides a constant dc voltage at the output stage. A theoretical analysis of the converter is presented, supported by simulation and experimental results. A 250 W down-scaled prototype was implemented in the laboratory...

  18. SUBCONTRACT REPORT: DC-DC Converter for Fuel Cell and Hybrid Vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Marlino, Laura D [ORNL; Zhu, Lizhi [Ballard Power Systems/Siemens VDO

    2007-07-01

    The goal of this project is to develop and fabricate a 5kW dc-dc converter with a baseline 14V output capability for fuel cell and hybrid vehicles. The major objectives for this dc-dc converter technology are to meet: Higher efficiency (92%); High coolant temperature,e capability (105 C); High reliability (15 Years/150,000miles); Smaller volume (5L); Lower weight (6kg); and Lower cost ($75/kW). The key technical challenge for these converters is the 105 C coolant temperatures. The power switches and magnetics must be designed to sustain these operating temperatures reliably, without a large cost/mass/volume penalty.

  19. Washington DC Metropolitan Area Drug Study Household and Non-Household Populations (DC-MADSH-1991)

    Data.gov (United States)

    U.S. Department of Health & Human Services — The DC Metropolitan Area Drug Study (DCMADS) was conducted in 1991, and included special analyses of homeless and transient populations and of women delivering live...

  20. Circuit description of unipolar DC-to-DC converters for APS storage ring quadrupoles and sextupoles

    International Nuclear Information System (INIS)

    McGhee, D.G.

    1993-01-01

    This paper describes the control, interlock, and power circuits for 680 unipolar switch mode DC-to-DC converters used to regulate the Advanced Photon Sources (APS's) storage ring quadrupole and sextupole magnet currents. Quadrupole current stability is ± 6x10 -5 and the sextupole current stability is ±3x10 -4 . The stability is obtained with pulse width modulation, operating at a switching frequency of 20kHz with full current switching. The converters are housed in 200 cabinets located on top of the storage ring tunnel. Raw DC power is distributed from 80 AC-to-DC power supplies, four at each of 20 locations around the storage ring. Voltages, currents, and temperatures are computer monitored and logged for the converters and magnets. All converters and magnets are water cooled with the flow and pressure monitored at the inlet and outlet of groups. Water is interlocked with the raw power supplies and not the individual converters

  1. Research of digital controlled DC/DC converter based on STC12C5410AD

    Science.gov (United States)

    Chen, Dan-Jiang; Jin, Xin; Xiao, Zhi-Hong

    2010-02-01

    In order to study application of digital control technology on DC/DC converter, principle of increment mode PID control algorithm was analyzed in the paper. Then, a SCM named STC12C5410AD was introduced with its internal resources and characteristics. The PID control algorithm can be implemented easily based on it. The output of PID control was used to change the value of a variable that is 255 times than duty cycle, and this reduced the error of calculation. The valid of the presented algorithm was verified by an experiment for a BUCK DC/DC converter. The experimental results indicated that output voltage of the BUCK converter is stable with low ripple.

  2. Washington DC Metropolitan Area Drug Study Homeless and Transient Population (DC-MADST-1991)

    Data.gov (United States)

    U.S. Department of Health & Human Services — The DC Metropolitan Area Drug Study (DCMADS) was conducted in 1991, and included special analyses of homeless and transient populations and of women delivering live...

  3. Improvement of burst-mode control of piezoelectric transformer based DC/DC converter

    International Nuclear Information System (INIS)

    Vasic, Dejan; Liu, Yuan-Ping; Costa, François; Schwander, Denis; Wu, Wen-Jong

    2013-01-01

    Burst-mode operation is adopted sometimes in piezoelectric transformer based converters for two major purposes: (1) to achieve voltage regulation in DC/DC converters and (2) to achieve dimming control in backlight inverters. Burst-mode control enables the converter to operate at a constant switching frequency as well as to maintain good efficiency at light load conditions. However, in practice, the piezoelectric transformer cannot instantly stop vibrating in the burst-mode due to its high quality factor. The delay in the output voltage change resulting from this behavior influences the accuracy of the regulation. This paper proposes a control strategy to make the piezoelectric transformer stop more quickly so as to enhance the accuracy of burst-mode control. The proposed method only modifies the control signal of the burst-mode driving circuit. The proposed control strategy is verified by experiments in a step-down 9 W DC/DC converter. (paper)

  4. Current Mode Control for LLC Series Resonant DC-to-DC Converters

    OpenAIRE

    Jinhaeng Jang; Syam Kumar Pidaparthy; Byungcho Choi

    2015-01-01

    Conventional voltage mode control only offers limited performance for LLC series resonant DC-to-DC converters experiencing wide variations in operational conditions. When the existing voltage mode control is employed, the closed-loop performance of the converter is directly affected by unavoidable changes in power stage dynamics. Thus, a specific control design optimized at one particular operating point could become unacceptable when the operational condition is varied. This paper presents a...

  5. LPV model for PV cell and fractional control of DC/DC converter for photovoltaic systems

    OpenAIRE

    Martínez González, Rubén; Bolea Monte, Yolanda; Grau Saldes, Antoni; Martínez García, Herminio

    2011-01-01

    This paper deals with the fractional modelling of a DC-DC converter, suitable in solar-powered electrical generation systems, and the design of a fractional controller for the aforementioned switching converter. A new model for PV cells is proposed in order to obtain a linear equation for V-I characteristic via scheduling dependence of temperature and irradiance. Due to the fractional nature of the ultracapacitors this kind of controller gives a suitable and good performance. Peer Reviewed

  6. LPV model for PV cells and fractional control of DC/DC converter for photovoltaic systems

    OpenAIRE

    Martínez González, Rubén; Bolea Monte, Yolanda; Grau Saldes, Antoni; Martínez García, Herminio

    2011-01-01

    This paper deals with the fractional modelling of a DC-DC converter, suitable in solar-powered electrical generation systems, and the design of a fractional controller for the aforementioned switching converter. A new model for PV cells is proposed in order to obtain a linear equation for VI characteristic via scheduling dependence of temperature and irradiance. Due to the fractional nature of the ultracapacitors this kind of controller gives a suitable and good performance. Peer Rev...

  7. Distributed maximum power point tracking in photovoltaic applications: active bypass DC/DC converter

    Directory of Open Access Journals (Sweden)

    Carlos Andrés Ramos-Paja

    2012-01-01

    Full Text Available Se propone una estructura de desvío activo para maximizar la producción de potencia en sistemas fotovoltaicos bajo condiciones irregulares de operación, comparando su eficiencia con soluciones individuales y distribuidas basadas en convertidores DC/DC convencionales. Los análisis y simulaciones realistas demuestran las ventajas del nuevo convertidor de desvío activo sobre soluciones basadas en convertidores Boost, Buck y Buck-Boost.

  8. Analisa Perbandingan Efisiensi Motor Dc Kompon Pendek Dengan Motor Dc Kompon Panjang Akibat Penambahan Kutub

    OpenAIRE

    Sitompul, Fuad Rahim

    2015-01-01

    Motor listrik merupakan perangkat elekromagnetis yang mengubah energi listrik menjadi energi mekanik. Motor DC memerlukan tegangan searah pada kumparan medan untuk diubah menjadi energi mekanik. Energi mekanik ini digunakan sebagai penggerak peralatan listrik seperti pompa,penggerak kipas angin, lift dan lain-lain. Karena penggunaannya yang cukup luas maka kinerjanya harus baik. Kinerja suatu motor DC dikatakan baik jika efisiensi motor tersebut tinggi. Hal itu dapat dicapai dengan mengatur b...

  9. Soft switching bidirectional DC-DC converter for ultracapacitor-batteries interface

    International Nuclear Information System (INIS)

    Adib, Ehsan; Farzanehfard, Hosein

    2009-01-01

    In this paper a new soft switching bidirectional DC-DC converter is introduced which can be applied as the interface circuit between ultracapacitors and batteries or fuel cells. All semiconductor devices in the proposed converter are soft switched while the control circuit remains PWM. Due to achieved soft switching condition, the energy conversion through the proposed converter is highly efficient. The proposed converter is analyzed and a prototype converter is implemented. The presented experimental results confirm the theoretical analysis.

  10. Soft switching bidirectional DC-DC converter for ultracapacitor-batteries interface

    Energy Technology Data Exchange (ETDEWEB)

    Adib, Ehsan; Farzanehfard, Hosein [Dept. of Electrical and Computer Engineering, Isfahan Univ. of Technology (Iran)

    2009-12-15

    In this paper a new soft switching bidirectional DC-DC converter is introduced which can be applied as the interface circuit between ultracapacitors and batteries or fuel cells. All semiconductor devices in the proposed converter are soft switched while the control circuit remains PWM. Due to achieved soft switching condition, the energy conversion through the proposed converter is highly efficient. The proposed converter is analyzed and a prototype converter is implemented. The presented experimental results confirm the theoretical analysis. (author)

  11. Comparative efficiency evaluation of buck and hybrid buck DC-DC converters for automotive applications

    DEFF Research Database (Denmark)

    Pelan, Ovidiu; Cornea, Octavian; Muntean, Nicolae

    2014-01-01

    This paper presents and discusses design considerations and efficiency investigation of a conventional step-down and a hybrid switched-capacitor DC-DC converter. Three MOSFETs with low on-resistance have been tested for each converter in order to find the most adequate switch for this application....... The experimental results and comparative efficiency graphs were obtained with a 1kW laboratory prototype dedicated for a 42/14V dual voltage automotive system....

  12. Simulating and Testing a DC-DC Half-Bridge SLR Converter

    Science.gov (United States)

    2013-06-01

    future pulse power demands with ship power, a large bank of capacitors or similar rapid discharge source is required. If capacitors are charged...Single Pulsed Avalanche Energy (j) I" Avalanche Current (i) E,, Repetilive Avalanche Energy (i) dv/dt Peak Diode Recovery dv/dt ® Po Total Power...SLR), battery charging, DC-DC, pulse power, power electronics, SLR converter 15. NUMBER OF PAGES 119 16. PRICE CODE 17. SECURITY CLASSIFICATION

  13. Sliding-mode control of single input multiple output DC-DC converter

    Science.gov (United States)

    Zhang, Libo; Sun, Yihan; Luo, Tiejian; Wan, Qiyang

    2016-10-01

    Various voltage levels are required in the vehicle mounted power system. A conventional solution is to utilize an independent multiple output DC-DC converter whose cost is high and control scheme is complicated. In this paper, we design a novel SIMO DC-DC converter with sliding mode controller. The proposed converter can boost the voltage of a low-voltage input power source to a controllable high-voltage DC bus and middle-voltage output terminals, which endow the converter with characteristics of simple structure, low cost, and convenient control. In addition, the sliding mode control (SMC) technique applied in our converter can enhance the performances of a certain SIMO DC-DC converter topology. The high-voltage DC bus can be regarded as the main power source to the high-voltage facility of the vehicle mounted power system, and the middle-voltage output terminals can supply power to the low-voltage equipment on an automobile. In the respect of control algorithm, it is the first time to propose the SMC-PID (Proportion Integration Differentiation) control algorithm, in which the SMC algorithm is utilized and the PID control is attended to the conventional SMC algorithm. The PID control increases the dynamic ability of the SMC algorithm by establishing the corresponding SMC surface and introducing the attached integral of voltage error, which endow the sliding-control system with excellent dynamic performance. At last, we established the MATLAB/SIMULINK simulation model, tested performance of the system, and built the hardware prototype based on Digital Signal Processor (DSP). Results show that the sliding mode control is able to track a required trajectory, which has robustness against the uncertainties and disturbances.

  14. Informational model verification of ZVS Buck quasi-resonant DC-DC converter

    Science.gov (United States)

    Vakovsky, Dimiter; Hinov, Nikolay

    2016-12-01

    The aim of the paper is to create a polymorphic informational model of a ZVS Buck quasi-resonant DC-DC converter for the modeling purposes of the object. For the creation of the model is applied flexible open standards for setting, storing, publishing and exchange of data in distributed information environment. The created model is useful for creation of many and different by type variants with different configuration of the composing elements and different inner model of the examined object.

  15. ITAR Free Commercial-of-the-Shelf DC/DC Converter

    Science.gov (United States)

    Denzinger, Wolfgang; Hintze, Thomas

    2014-08-01

    A commercial-of-the-shelf (COTS) DC/DC converter for digital space equipment has been developed by ASP under ESA contract with special emphasis on low cost, no use of ITAR listed EEE parts like Mosfets, minimum number of rad-hard digital IC's and a design tolerance against single event effects by appropriate filtering. However, the intention to qualify this discrete converter design for a low cost FM series production was difficult due to the high up-sceening cost of EEE-parts with one lot guarantee and minimum-by. To overcome this problem, in a next step a redesign of the DC/DC converter was performed with all semiconductors like bipolar transistors, rectifiers and zener diodes packaged into hybrids. With this approach it was possible to buy a high number of less expensive wafers or dies from one lot, to perform a lot acceptance test and to integrate the dies into hybrid packages with further up- screening for FM use. The semiconductors have been packaged into three signal hybrids with 44 pins and one power hybrid with 24 pins for the dissipating transistors and rectifiers. The design of the hybrids is such, that all integrated semiconductors can be tested individually. The qualification of four EQM DC/DC converters with different combinations of output voltages has been successfully performed and two FM's have been manufactured and tested.

  16. Design and implementation of current fed DC-DC converter for PHEV application using renewable source

    Science.gov (United States)

    Milind Metha, Manish; Tutki, Sanjay; Rajan, Aju; Elangovan, D.; Arunkumar, G.

    2017-11-01

    As the fossil fuels are depleting day by day, the use of renewable energy sources came into existence and they evolved a lot lately. To increase efficiency and productivity in the hybrid vehicles, the existence less efficient petroleum and diesel IC engines need to be replaced with the new and efficient converters with renewable energy sources. This has to be done in such a way that impacts three factors mainly: cost, efficiency and reliability. The PHEVs that have been launched and the upcoming PHEVs using converters with voltage range around 380V to 400V generated with power ranges between 2.4KW to 2.8KW. The basic motto of this paper is to design a prolific converter while considering the factor such as cost and size. In this paper, a two stage DC-DC converter is proposed and the proposed DC-DC converter is utilized to endeavour voltage from 24V (photovoltaic source) to a yield voltage of 400V and to meet the power demand of 250W, since only one panel is being used for this proposed paper. This paper discuss in detail about why and how the current fed DC-DC converter is utilized along with a voltage doubler, thus reducing transformer turns and thereby reducing overall size of the product. Simulation and hardware results have been presented along with calculations for duty cycle required for firing sequence for different values of transformer turns.

  17. CAMEX-4 DC-8 DROPSONDE SYSTEM V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The CAMEX-4 DC-8 Dropsonde System dataset was collected by the DC-8 Dropsonde System (D8D) uses dropwindsonde and Global Positioning System (GPS) receivers to...

  18. control of a dc motor using fuzzy logic control algorithm

    African Journals Online (AJOL)

    user

    controller in the control performance of an industrial type DC motor using MATLAB. The fuzzy logic .... controlled separately excited permanent magnet DC motor (PMDC). ... When the field current is constant, the flux induced by the field ...

  19. Brushless dc motor uses electron beam switching tube as commutator

    Science.gov (United States)

    Studer, P.

    1965-01-01

    Electron beam switching tube eliminates physical contact between rotor and stator in brushless dc motor. The tube and associated circuitry control the output of a dc source to sequentially energize the motor stator windings.

  20. Trends and determinants of cycling in the Washington, DC region.

    Science.gov (United States)

    2011-01-01

    This report analyzes cycling trends, policies, and commuting in the Washington, DC area. The analysis is divided into two parts. : Part 1 focuses on cycling trends and policies in Washington (DC), Alexandria (VA), Arlington County (VA), Fairfax Count...

  1. Activité larvicide sur Anopheles gambiae Giles et composition chimique des huiles essentielles extraites de quatre plantes cultivées au Cameroun

    Directory of Open Access Journals (Sweden)

    Tchoumbougnang F.

    2009-01-01

    Full Text Available Larvicidal activity against Anopheles gambiae Giles and chemical composition of essential oils from four plants cultivated in Cameroon. The chemical composition of the essential oils obtained by hydrodistillation of dry leaves from Cymbopogon citrates (DC. Stapf, Ocimum canum Sims, Ocimum gratissimum L. var 'gratissimum' L. and Thymus vulgaris L. cultivated in Cameroon were analyzed and their larvicidal activity against fourth instar larvae of Anopheles gambiae Giles were determined. The yields of extraction indicate that T. vulgaris (0.95% was richer in essential oil than C. citratus (0.67%. O. canum and O. gratissimum have approximately the same content in volatile constituents (0.59% and 0.60%, respectively. The analyses by GC and GC/MS showed that these oils are monoterpenic (86.8-97.4%. Oxygenated monoterpenes predominate in C. citratus and O. canum (81.6% and 68.9%, respectively while O. gratissimum oil contains a majority of monoterpene hydrocarbons (61.0%. T. vulgaris is characterized by the same proportion of monoterpene hydrocarbons (45.6% and oxygenated monoterpenes (48.9%. The main compounds found in the essential oil of C. citratus are acyclic monoterpenes such as geraniol (15.6%, geranial (39.3%, neral (21.9% and myrcene (14.0%. The essential oil of T. vulgaris is characterized by p-menthane structures given by thymol (40.1%, p-cymene (23.4% and γ-terpinene (15.1%; p-cymene (32.1% and thymol (24.3% were also the constituents quantitatively important in O. gratissimum essential oil while linalool (56.3% and limonene (10.9% were predominant in O. canum. Bioassay test done by the World Health Organization standard protocol revealed that these essential oils have remarkable larvicidal properties as they could induce 100% mortality in the larvae of A. gambiae at the concentration of 100 ppm for C. citratus, 200 ppm with T. vulgaris, 350 ppm for O. gratissimum and 400 ppm for O. canum. Their LC50 and LC80 show the same reactivity order

  2. Design of an Input-Parallel Output-Parallel LLC Resonant DC-DC Converter System for DC Microgrids

    Science.gov (United States)

    Juan, Y. L.; Chen, T. R.; Chang, H. M.; Wei, S. E.

    2017-11-01

    Compared with the centralized power system, the distributed modularized power system is composed of several power modules with lower power capacity to provide a totally enough power capacity for the load demand. Therefore, the current stress of the power components in each module can then be reduced, and the flexibility of system setup is also enhanced. However, the parallel-connected power modules in the conventional system are usually controlled to equally share the power flow which would result in lower efficiency in low loading condition. In this study, a modular power conversion system for DC micro grid is developed with 48 V dc low voltage input and 380 V dc high voltage output. However, in the developed system control strategy, the numbers of power modules enabled to share the power flow is decided according to the output power at lower load demand. Finally, three 350 W power modules are constructed and parallel-connected to setup a modular power conversion system. From the experimental results, compared with the conventional system, the efficiency of the developed power system in the light loading condition is greatly improved. The modularized design of the power system can also decrease the power loss ratio to the system capacity.

  3. DC-DC Type High-Frequency Link DC for Improved Power Quality of Cascaded Multilevel Inverter

    Science.gov (United States)

    Sadikin, Muhammad; Senjyu, Tomonobu; Yona, Atsushi

    2013-06-01

    Multilevel inverters are emerging as a new breed of power converter options for power system applications. Recent advances in power switching devices enabled the suitability of multilevel inverters for high voltage and high power applications because they are connecting several devices in series without the need of component matching. Usually, a transformerless battery energy storage system, based on a cascaded multilevel inverter, is used as a measure for voltage and frequency deviations. System can be reduced in size, weight, and cost of energy storage system. High-frequency link circuit topology is advantageous in realizing compact and light-weight power converters for uninterruptible power supply systems, new energy systems using photovoltaic-cells, fuel-cells and so on. This paper presents a DC-DC type high-frequency link DC (HFLDC) cascaded multilevel inverter. Each converter cell is implemented a control strategy for two H-bridge inverters that are controlled with the same multicarrier pulse width modulation (PWM) technique. The proposed cascaded multilevel inverter generates lower voltage total harmonic distortion (THD) in comparison with conventional cascaded multilevel inverter. Digital simulations are carried out using PSCAD/EMTDC to validate the performance of the proposed cascaded multilevel inverter.

  4. Unregulated Series Resonant Converter for Interlinking DC Nanogrids

    DEFF Research Database (Denmark)

    Tomas Manez, Kevin; Zhang, Zhe; Ouyang, Ziwei

    2017-01-01

    bidirectional converter to interlink a 400V DC bus with a 48V DC bus ispresented. The proposed converter is based on a LLC resonant converter operating as a DC transformer at a fixed frequency and duty cycle without any complex control strategy. A clearand simplified design procedure for high efficiency...

  5. Controller design and stability analysis of grid connected DC microgrid

    DEFF Research Database (Denmark)

    Chauhan, Rajeev Kumar; Chauhan, Kalpana; Guerrero, Josep M.

    2018-01-01

    DC microgrids are desired to provide the electricity for the remote areas which are far from the main grid. The microgrid gets popularity because DC power sources such as photovoltaics (PVs), battery banks, and fuel cells can be interconnected without AC/DC converters. The stochastic nature of PV...

  6. Active superconducting DC fault current limiter based on flux compensation

    International Nuclear Information System (INIS)

    Shi Jing; Tang Yuejin; Wang, Chen; Zhou Yusheng; Li Jingdong; Ren Li; Chen Shijie

    2006-01-01

    With the extensive application of DC power systems, suppression of DC fault current is an important subject that guarantees system security. This paper presents an active superconducting DC fault current limiter (DC-SFCL) based on flux compensation. The DC-SFCL is composed of two superconducting windings wound on a single iron core, the primary winding is in series with DC power system, and the second winding is connected with AC power system through a PWM converter. In normal operating state, the flux in the iron core is compensated to zero, and the SFCL has no influence on DC power system. In the case of DC system accident, through regulating the active power exchange between the SFCL's second winding and the AC power system, the current on the DC side can be limited to different level complying with the system demand. Moreover, the PWM converter that interface the DC system and AC system can be controlled as a reactive power source to supply voltage support for the AC side, which has little influence on the performance of SFCL. Using MATLAB SIMULINK, the mathematic model of the DC-SFCL is created, simulation results validate the dynamics of system, and the performance of DC-SFCL is confirmed

  7. Overvoltage protection in DC power systems; Ueberspannungsschutz in Gleichstromanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Birkl, Josef; Zahlmann, Peter [Dehn + Soehne GmbH + Co.KG, Neumarkt (Germany)

    2012-02-15

    The utilisation of DC power systems has increased dramatically in the recent years. In addition to traditional DC applications such as in telecommunications and railway engineering a variety of DC applications arise due to a rapid spread of photovoltaic systems. Current projects for the e-mobility expand the scope of application.

  8. On the modelling of linear-assisted DC-DC voltage regulators for photovoltaic solar energy systems

    Science.gov (United States)

    Martínez-García, Herminio; García-Vílchez, Encarna

    2017-11-01

    This paper shows the modelling of linear-assisted or hybrid (linear & switching) DC/DC voltage regulators. In this kind of regulators, an auxiliary linear regulator is used, which objective is to cancel the ripple at the output voltage and provide fast responses for load variations. On the other hand, a switching DC/DC converter, connected in parallel with the linear regulator, allows to supply almost the whole output current demanded by the load. The objective of this topology is to take advantage of the suitable regulation characteristics that series linear voltage regulators have, but almost achieving the high efficiency that switching DC/DC converters provide. Linear-assisted DC/DC regulators are feedback systems with potential instability. Therefore, their modelling is mandatory in order to obtain design guidelines and assure stability of the implemented power supply system.

  9. First Implementation of a Two-Stage DC-DC Conversion Powering Scheme for the CMS Phase-2 Outer Tracker

    CERN Document Server

    Feld, Lutz Werner; Karpinski, Waclaw; Klein, Katja; Lipinski, Martin; Pauls, Alexander Josef; Preuten, Marius; Rauch, Max Philip; Wangelik, Frederik; Wlochal, Michael

    2017-01-01

    The 2S silicon strip modules for the CMS Phase-2 tracker upgrade will require two operating voltages. These will be provided via a two-step DC-DC conversion powering scheme, in which one DC-DC converter delivers 2.5\\,V while the second DC-DC converter receives 2.5\\,V at its input and converts it to 1.2\\,V. The DC-DC converters will be mounted on a flex PCB, the service hybrid, together with an opto-electrical converter module (VTRx+) and a serializer (LP-GBT). The service hybrid will be mounted directly on the 2S module. A prototype service hybrid has been developed and its performance has been evaluated, including radiative and conductive noise emissions, and efficiency. In addition system tests with a prototype module have been performed. In this report the service hybrid will be described and the test results will be summarized.

  10. All Digital Switch-Mode DC/DC Converters with BIST Functionality for Harsh Space Environments, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The Space Micro Arizona State University (ASU) team will develop an all-digitally controlled, wide temperature range point-of-load switch-mode DC-DC regulator core...

  11. DC-Voltage Fluctuation Elimination Through a DC-Capacitor Current Control for DFIG Converters Under Unbalanced Grid Voltage Conditions

    DEFF Research Database (Denmark)

    Liu, Changjin; Xu, Dehong; Zhu, Nan

    2013-01-01

    Unbalanced grid voltage causes a large second-order harmonic current in the dc-link capacitors as well as dc-voltage fluctuation, which potentially will degrade the lifespan and reliability of the capacitors in voltage source converters. This paper proposes a novel dc-capacitor current control...... method for a grid-side converter (GSC) to eliminate the negative impact of unbalanced grid voltage on the dc-capacitors. In this method, a dc-capacitor current control loop, where a negative-sequence resonant controller is used to increase the loop gain, is added to the conventional GSC current control...... loop. The rejection capability to the unbalanced grid voltage and the stability of the proposed control system are discussed. The second-order harmonic current in the dc capacitor as well as dc-voltage fluctuation is very well eliminated. Hence, the dc capacitors will be more reliable under unbalanced...

  12. Next-Generation Shipboard DC Power System

    DEFF Research Database (Denmark)

    Jin, Zheming; Sulligoi, Giorgio; Cuzner, Rob

    2016-01-01

    sources (RES) are commonly recognized as the major driven force of the revolution, the outburst of customer electronics and new kinds of household electronics is also powering this change. In this context, dc power distribution technologies have made a comeback and keep gaining a commendable increase...... in research interests and industrial applications. In addition, the concept of flexible and smart distribution has also been proposed, which tends to exploit distributed generation and pack the distributed RESs and local electrical loads as an independent and self-sustainable entity, namely microgrid....... At present, the research of dc microgrid has investigated and developed a series of advanced methods in control, management and objective-oriented optimization, which would found the technical interface enabling the future applications in multiple industrial areas, such as smart buildings, electric vehicles...

  13. Artificial noise due to DC electric trains

    International Nuclear Information System (INIS)

    Senanayake, W.E.

    1987-08-01

    The current distribution in a DC railway and the resulting magnetic effects have been modelled using the parameters of the DC railway networks in Italy. The results show that the magnetic perturbations are substantially high in the vicinity of electrified railway lines. The order of magnitude of the induced field can be as significant as ∼ 40nT at a distance of ≅ 2km from the railway line indicating that geophysical techniques that employ natural magnetic anomalies can be badly effected, within this range. The magnetic effects rapidly decay with increasing distance, but the noise level could be significant even at a range of ∼ 10km. Also, these induced anomalies vary significantly with the conductivity of the ground. When the conductivity is high it is possible that the railway currents dispersed through the ground interact with those induced in the earth, causing a severe disruption to the telluric measurements. (author). 11 refs, 10 figs, 1 tab

  14. Macroscopic quantum tunneling in a dc SQUID

    International Nuclear Information System (INIS)

    Chen, Y.C.

    1986-01-01

    The theory of macroscopic quantum tunneling is applied to a current-biased dc SQUID whose dynamics can be described by a two-dimensional mechanical system with a dissipative environment. Based on the phenomenological model proposed by Caldeira and Leggett, the dissipative environment is represented by a set of harmonic oscillators coupling to the system. After integrating out the environmental degrees of freedom, an effective Euclidean action is found for the two-dimensional system. The action is used to provide the quantum tunneling rate formalism for the dc SQUID. Under certain conditions, the tunneling rate reduces to that of a single current-biased Josephson junction with an adjustable effective critical current

  15. Universality of DC electrical conductivity from holography

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Xian-Hui, E-mail: gexh@shu.edu.cn [Shanghai Key Laboratory of High Temperature Superconductors, Department of Physics, Shanghai University, Shanghai, 200444 (China); Department of Physics, University of California, San Diego, CA92122 (United States); Sin, Sang-Jin, E-mail: sjsin@hangyang.ac.kr [Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Wu, Shao-Feng, E-mail: sfwu@shu.edu.cn [Department of Physics, Shanghai University, Shanghai, 200444 (China)

    2017-04-10

    We propose a universal formula of dc electrical conductivity in rotational- and translational-symmetries breaking systems via the holographic duality. This formula states that the ratio of the determinant of the dc electrical conductivities along any spatial directions to the black hole area density in zero-charge limit has a universal value. As explicit illustrations, we give several examples elucidating the validation of this formula: We construct an anisotropic black brane solution, which yields linear in temperature for the in-plane resistivity and insulating behavior for the out-of-plane resistivity; We also construct a spatially isotropic black brane solution that both the linear-T and quadratic-T contributions to the resistivity can be realized.

  16. A comprehensive analysis and hardware implementation of control strategies for high output voltage DC-DC boost power converter

    OpenAIRE

    Padmanaban, Sanjeevikumar; Grandi, Gabriele; Blaabjerg, Frede; Wheeler, Patrick; Siano, Pierluigi; Hammami, Manel

    2017-01-01

    Classical DC-DC converters used in high voltage direct current (HVDC) power transmission systems, lack in terms of efficiency, reduced transfer gain and increased cost with sensor (voltage/current) numbers. Besides, the internal self-parasitic behavior of the power components reduces the output voltage and efficiency of classical HV converters. This paper deals with extra high-voltage (EHV) dc-dc boost converter by the application of voltage-lift technique to overcome the aforementioned defic...

  17. Power Oscillations Damping in DC Microgrids

    DEFF Research Database (Denmark)

    Hamzeh, Mohsen; Ghafouri, Mohsen; Karimi, Houshang

    2016-01-01

    This paper proposes a new control strategy for damping of power oscillations in a multi-source dc microgrid. A parallel combination of a fuel cell (FC), a photovoltaic (PV) system and a supercapacitor (SC) are used as a hybrid power conversion system (HPCS). The SC compensates for the slow transi...... of the proposed control scheme is verified using hardware-in-the-loop (HIL) simulations carried out in OPAL-RT technologies....

  18. Circuit Regulates Speed Of dc Motor

    Science.gov (United States)

    Weaver, Charles; Padden, Robin; Brown, Floyd A., Jr.

    1990-01-01

    Driving circuit regulates speed of small dc permanent-magnet motor in tape recorder. Two nested feedback loops maintain speed within 1 percent of constant value. Inner loop provides coarse regulation, while outer loop removes most of variation in speed that remains in the presence of regulation by the inner loop. Compares speed of motor with commanded speed and adjusts current supplied to motor accordingly.

  19. DC Characterization of Different Advanced MOSFET Architectures

    International Nuclear Information System (INIS)

    Jomaah, J.; Fadlallah, M.; Ghibaudo, G.

    2011-01-01

    A review of recent results concerning the DC characterization of FD- and Double Gate SOI MOSFET's and FinFETs in modern CMOS technologies is given. By proper extraction techniques, distinction between the different interaction mechanisms is done. Parameter extraction conducted at room and low temperature clearly indicates that the mobility is directly impacted by shrinking the gate length in sub 100nm architectures. (author)

  20. Development of a smart DC grid model

    Energy Technology Data Exchange (ETDEWEB)

    Dalimunthe, Amty Ma’rufah Ardhiyah; Mindara, Jajat Yuda; Panatarani, Camellia; Joni, I. Made, E-mail: imadejoni@phys.unpad.ac.id [Lab. of Instrumentation System and Functional Material Processing, Physics Department, Faculty of Mathematics and Natural Sciences, Padjadjaran University, Jl. Raya Bandung-Sumedang KM21, Jatinangor 45363, Jawa Barat (Indonesia)

    2016-03-11

    Smart grid and distributed generation should be the solution of the global climate change and the crisis energy of the main source of electrical power generation which is fossil fuel. In order to meet the rising electrical power demand and increasing service quality demands, as well as reduce pollution, the existing power grid infrastructure should be developed into a smart grid and distributed power generation which provide a great opportunity to address issues related to energy efficiency, energy security, power quality and aging infrastructure systems. The conventional of the existing distributed generation system is an AC grid while for a renewable resources requires a DC grid system. This paper explores the model of smart DC grid by introducing a model of smart DC grid with the stable power generation give a minimal and compressed circuitry that can be implemented very cost-effectively with simple components. The PC based application software for controlling was developed to show the condition of the grid and to control the grid become ‘smart’. The model is then subjected to a severe system perturbation, such as incremental change in loads to test the performance of the system again stability. It is concluded that the system able to detect and controlled the voltage stability which indicating the ability of power system to maintain steady voltage within permissible rangers in normal condition.

  1. Development of a smart DC grid model

    International Nuclear Information System (INIS)

    Dalimunthe, Amty Ma’rufah Ardhiyah; Mindara, Jajat Yuda; Panatarani, Camellia; Joni, I. Made

    2016-01-01

    Smart grid and distributed generation should be the solution of the global climate change and the crisis energy of the main source of electrical power generation which is fossil fuel. In order to meet the rising electrical power demand and increasing service quality demands, as well as reduce pollution, the existing power grid infrastructure should be developed into a smart grid and distributed power generation which provide a great opportunity to address issues related to energy efficiency, energy security, power quality and aging infrastructure systems. The conventional of the existing distributed generation system is an AC grid while for a renewable resources requires a DC grid system. This paper explores the model of smart DC grid by introducing a model of smart DC grid with the stable power generation give a minimal and compressed circuitry that can be implemented very cost-effectively with simple components. The PC based application software for controlling was developed to show the condition of the grid and to control the grid become ‘smart’. The model is then subjected to a severe system perturbation, such as incremental change in loads to test the performance of the system again stability. It is concluded that the system able to detect and controlled the voltage stability which indicating the ability of power system to maintain steady voltage within permissible rangers in normal condition.

  2. Frequency analysis of DC tolerant current transformers

    International Nuclear Information System (INIS)

    Mlejnek, P; Kaspar, P

    2013-01-01

    This article deals with wide frequency range behaviour of DC tolerant current transformers that are usually used in modern static energy meters. In this application current transformers must comply with European and International Standards in their accuracy and DC tolerance. Therefore, the linear DC tolerant current transformers and double core current transformers are used in this field. More details about the problems of these particular types of transformers can be found in our previous works. Although these transformers are designed mainly for power distribution network frequency (50/60 Hz), it can be interesting to understand their behaviour in wider frequency range. Based on this knowledge the new generations of energy meters with measuring quality of electric energy will be produced. This solution brings better measurement of consumption of nonlinear loads or measurement of non-sinusoidal voltage and current sources such as solar cells or fuel cells. The determination of actual power consumption in such energy meters is done using particular harmonics component of current and voltage. We measured the phase and ratio errors that are the most important parameters of current transformers, to characterize several samples of current transformers of both types

  3. Ac-dc converter firing error detection

    International Nuclear Information System (INIS)

    Gould, O.L.

    1996-01-01

    Each of the twelve Booster Main Magnet Power Supply modules consist of two three-phase, full-wave rectifier bridges in series to provide a 560 VDC maximum output. The harmonic contents of the twelve-pulse ac-dc converter output are multiples of the 60 Hz ac power input, with a predominant 720 Hz signal greater than 14 dB in magnitude above the closest harmonic components at maximum output. The 720 Hz harmonic is typically greater than 20 dB below the 500 VDC output signal under normal operation. Extracting specific harmonics from the rectifier output signal of a 6, 12, or 24 pulse ac-dc converter allows the detection of SCR firing angle errors or complete misfires. A bandpass filter provides the input signal to a frequency-to-voltage converter. Comparing the output of the frequency-to-voltage converter to a reference voltage level provides an indication of the magnitude of the harmonics in the ac-dc converter output signal

  4. Marvel and DC Characters Inspired by Arachnids

    Directory of Open Access Journals (Sweden)

    Elidiomar Ribeiro Da-Silva

    2014-12-01

    Full Text Available This article compares arachnid-based Marvel and DC comics characters. The composition of a comic book character often has interesting ‘real-life’ influences. Given the strong connection between arachnids (especially spiders, scorpions and mites, all belonging to the zoological class 'Arachnida' and human beings it is not surprising that they have inspired many fictional characters. We recorded 84 Marvel Comics characters and 40 DC Comics characters, detailed in the dataset that accompanies the article (Da-Silva 2014. Most characters have been created recently, since the 1990s. Marvel has significantly more arachnid characters than DC. As for taxonomic classification, the characters were based mostly on spiders (zoological order 'Araneae'. Of the total characters, the majority are human beings, but an overwhelming number have at least some typical arachnid features. Villains (60.91% of total are significantly more numerous, considering the sum of the two publishers. Arachnids have bad reputation for being dangerous (Thorp and Woodson 1976; Ruppert and Barnes 1996. Since the public usually considers spiders, scorpions and mites “harmful” in general, we expected a larger contingent of villains. However, there was no statistical difference between the amount of villains and heroes in Marvel characters. It did not happen probably due to the success of one character: the Amazing Spider-Man.

  5. Performance of 22.4-kW nonlaminated-frame dc series motor with chopper controller. [a dc to dc voltage converter

    Science.gov (United States)

    Schwab, J. R.

    1979-01-01

    Performance data obtained through experimental testing of a 22.4 kW traction motor using two types of excitation are presented. Ripple free dc from a motor-generator set for baseline data and pulse width modulated dc as supplied by a battery pack and chopper controller were used for excitation. For the same average values of input voltage and current, the motor power output was independent of the type of excitation. However, at the same speeds, the motor efficiency at low power output (corresponding to low duty cycle of the controller) was 5 to 10 percentage points lower on chopped dc than on ripple free dc. The chopped dc locked-rotor torque was approximately 1 to 3 percent greater than the ripple free dc torque for the same average current.

  6. Digital DC beam current measurement on SSRF storage ring

    International Nuclear Information System (INIS)

    Xiong Liang; Yin Chongxian; Liu Ming; Chen Jianfeng

    2011-01-01

    Both DC current transformer (DCCT) and integrating current transformer (ICT) can be used in DC beam current measurement. The ICT has strong capability of resisting electromagnetic interference, but its measurement accuracy cannot satisfy the DC beam current measurement requirement when using traditional high speed A/D. With high resolution A/D and equivalent sampling system, DC beam current measuring system based on ICT can reach high accuracy compared with DCCT system. In this paper, the ICT-based DC beam current measurement, equivalent sampling method and testing results at Shanghai Synchrotron Radiation Facility(SSRF) is described. (authors)

  7. Controlling DC permeability in cast steels

    International Nuclear Information System (INIS)

    Sumner, Aaran; Gerada, Chris; Brown, Neil; Clare, Adam

    2017-01-01

    Annealing (at multiple cooling rates) and quenching (with tempering) was performed on specimens of cast steel of varying composition. The aim was to devise a method for selecting the steel with the highest permeability, from any given range of steels, and then increasing the permeability by heat treatment. Metallographic samples were imaged using optical microscopy to show the effect of the applied heat treatments on the microstructure. Commonly cast steels can have DC permeability altered by the careful selection of a heat treatment. Increases of up to 381% were achieved by annealing using a cooling rate of 6.0 °C/min. Annealing was found to cause the carbon present in the steel to migrate from grain boundaries and from within ferrite crystals into adjacent pearlite crystals. The migration of the carbon resulted in less carbon at grain boundaries and within ferrite crystals reducing the number of pinning sites between magnetic domains. This gives rise to a higher permeability. Quenching then tempering was found to cause the formation of small ferrite crystals with the carbon content of the steel predominately held in the martensitic crystal structures. The results show that with any given range of steel compositions the highest baseline DC permeability will be found with the steel that has the highest iron content and the lowest carbon content. For the samples tested in this paper a cooling rate of 4.5 °C/min resulted in the relative permeability of the sample with the highest baseline permeability, AS4, increasing from 783 to 1479 at 0.5 T. This paper shows how heat treatments commonly applied to hypoeutectoid cast steels, to improve their mechanical performance, can be used to also enhance electromagnetic properties of these alloys. The use of cast steels allows the creation of DC components for electrical machines not possible by the widely used method of stacking of electrical grade sheet steels. - Highlights: • A range of structural steels had their

  8. Controlling DC permeability in cast steels

    Energy Technology Data Exchange (ETDEWEB)

    Sumner, Aaran, E-mail: aaran.sumner@nottingham.ac.uk [University of Nottingham, Nottingham University Park Campus, Nottingham NG7 2RD, England (United Kingdom); Gerada, Chris, E-mail: chris.gerada@nottingham.ac.uk [Electrical Machines, University of Nottingham, Tower Building, Nottingham NG7 2RD, England (United Kingdom); Brown, Neil, E-mail: neil.brown@cummins.com [Advanced Electrical Machines Research and Technology at Cummins Power Generation, Peterborough PE2 6FZ, England (United Kingdom); Clare, Adam, E-mail: adam.clare@nottingham.ac.uk [Advanced Manufacturing, University of Nottingham, University Park Campus, Nottingham NG7 2RD, England (United Kingdom)

    2017-05-01

    Annealing (at multiple cooling rates) and quenching (with tempering) was performed on specimens of cast steel of varying composition. The aim was to devise a method for selecting the steel with the highest permeability, from any given range of steels, and then increasing the permeability by heat treatment. Metallographic samples were imaged using optical microscopy to show the effect of the applied heat treatments on the microstructure. Commonly cast steels can have DC permeability altered by the careful selection of a heat treatment. Increases of up to 381% were achieved by annealing using a cooling rate of 6.0 °C/min. Annealing was found to cause the carbon present in the steel to migrate from grain boundaries and from within ferrite crystals into adjacent pearlite crystals. The migration of the carbon resulted in less carbon at grain boundaries and within ferrite crystals reducing the number of pinning sites between magnetic domains. This gives rise to a higher permeability. Quenching then tempering was found to cause the formation of small ferrite crystals with the carbon content of the steel predominately held in the martensitic crystal structures. The results show that with any given range of steel compositions the highest baseline DC permeability will be found with the steel that has the highest iron content and the lowest carbon content. For the samples tested in this paper a cooling rate of 4.5 °C/min resulted in the relative permeability of the sample with the highest baseline permeability, AS4, increasing from 783 to 1479 at 0.5 T. This paper shows how heat treatments commonly applied to hypoeutectoid cast steels, to improve their mechanical performance, can be used to also enhance electromagnetic properties of these alloys. The use of cast steels allows the creation of DC components for electrical machines not possible by the widely used method of stacking of electrical grade sheet steels. - Highlights: • A range of structural steels had their

  9. Series-Connected High Frequency Converters in a DC Microgrid System for DC Light Rail Transit

    Directory of Open Access Journals (Sweden)

    Bor-Ren Lin

    2018-01-01

    Full Text Available This paper studies and presents a series-connected high frequency DC/DC converter connected to a DC microgrid system to provide auxiliary power for lighting, control and communication in a DC light rail vehicle. Three converters with low voltage and current stresses of power devices are series-connected with single transformers to convert a high voltage input to a low voltage output for a DC light rail vehicle. Thus, Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs with a low voltage rating and a turn-on resistance are adopted in the proposed circuit topology in order to decrease power losses on power switches and copper losses on transformer windings. A duty cycle control with an asymmetric pulse-width modulation is adopted to control the output voltage at the desired voltage level. It is also adopted to reduce switching losses on MOSFETs due to the resonant behavior from a leakage inductor of an isolated transformer and output capacitor of MOSFETs at the turn-on instant. The feasibility and effectiveness of the proposed circuit have been verified by a laboratory prototype with a 760 V input and a 24 V/60 A output.

  10. RF-superimposed DC and pulsed DC sputtering for deposition of transparent conductive oxides

    International Nuclear Information System (INIS)

    Stowell, Michael; Mueller, Joachim; Ruske, Manfred; Lutz, Mark; Linz, Thomas

    2007-01-01

    Transparent conductive oxide films are widely used materials for electronic applications such as flat panel displays and solar cells. The superposition of DC and pulsed DC power by a certain fraction of RF power was applied to deposit indium tin oxide films. This technique allows an additional tuning of different parameters relevant to film growth, and yields high quality films even under kinetically limited conditions. A long-term stable RF/DC process could be realized by using different combinations of standard power supply components, which includes a fully reliable arc handling system for both the RF and DC generators. The effectiveness of the arc handling system is illustrated by the current and voltage behavior recorded for actual arcing events. The resistivity of indium tin oxide films is strongly influenced by the respective sputtering mode. The best resistivity values of 145-148 μΩ cm were obtained by RF-superimposed pulsed DC sputtering at a pulse frequency between 100 and 200 kHz and a substrate temperature as low as 140 deg. C. In addition, the films were extremely smooth with a surface roughness of 1-2.5 nm

  11. Effect of plant essential oils on Ralstonia solanacearum race 4 causing bacterial wilt of edible ginger

    Science.gov (United States)

    Palmarosa (Cymbopogon martini), lemongrass (C. citratus) and eucalyptus (Eucalyptus globulus) oils were investigated for their effects on Ralstonia solanacearum race 4, and their potential use as bio-fumigants for treating pathogen- infested edible ginger (Zingiber officinale R.) fields. Three conce...

  12. In vitro screening of selected essential oils from medicinal plants ...

    African Journals Online (AJOL)

    Enteric methane production lowers the efficiency of feed utilization in ruminants and contributes to greenhouse gas emissions which are responsible for global climate change. This study examined the effects of nine essential oils (EO) from Citrus aurantifolia, Cymbopogon citratus, Eucalyptus citriodora, Laurus nobilis, ...

  13. Comparative Study of Root, Stalk and Leaf Essential Oils of ...

    African Journals Online (AJOL)

    MBI

    2017-03-03

    Mar 3, 2017 ... ABSTRACT. The root, stalk and leaf essential oils of Cymbopogon citratus grown in Kaduna, North Central Nigeria were extracted separately by hydrodistillation and characterized by GC-MS. The chemical composition analysis by. GC-MS of the oils allowed the identification of 34, 26 and 16 compounds ...

  14. In vitro evaluation of the effect of aqueous extracts of Agave sisalana ...

    African Journals Online (AJOL)

    Objectives: To evaluate the effects of aqueous extracts of Agave sisalana (sisal) and Cymbopogon citratus (lemon grass) on mycelial growth and conidia production of Pyricularia oryzae, causal agent of Rice Blast. Methodology and Results: The plants aqueous extracts were used at concentrations 0.1; 0.2; 0.3; 0.4; 0.5;1; 2; ...

  15. Author Details

    African Journals Online (AJOL)

    Sankara, P. Vol 85 (2015) - Articles Assessing the toxicity level of some useful mushrooms of Burkina Faso (West Africa) Abstract PDF · Vol 89 (2015) - Articles In vitro evaluation of the effect of aqueous extracts of Agave sisalana and Cymbopogon citratus on mycelial growth and conidia production of Pyricularia oryzae, ...

  16. Efficacy of some essential oils in mice infected with Trypanosoma cruzi

    African Journals Online (AJOL)

    Purpose: To evaluate the efficacy of orally administered Cymbopogon citratus, Zingiber officinale and Syzygium aromaticum essential oils (EOs) in mice infected with Trypanosoma cruzi. Methods: Three experiments were conducted with 48 Swiss mice each. The animals were inoculated with 2 x 106 metacyclic ...

  17. A comparative assessment of the the nutritional contents of 'wara' a ...

    African Journals Online (AJOL)

    The processing line of West African soft cheese varieties (processed with Calotropis procera (Sodom apple) and Cymbopogon citratus (lemon grass) leaf extracts was assessed for nutrient compositions (nitrogen, crude protein, fat, lactose, moisture content), pH, total aerobic plate count and trace elements (Fe, Zn, Cu, Mn, ...

  18. Bioactivity of essential oils from medicinal plants of Cameroon and ...

    African Journals Online (AJOL)

    The EOs of Eucalyptus globulus, Cymbopogon citratus, Xylopia aethiopica, Thymus vulgaris, Ocimum canum, Cananga odorata, Citrus medica, Citrus paradisi and Citrus reticulata were screened against the most incriminated bacterial species using the spot-on-agar test and microdilution methods. Some of the EOs with ...

  19. Evaluation of in vivo antimalarial activity of the ethanolic leaf extracts ...

    African Journals Online (AJOL)

    Prof. Ogunji

    Plasmodium berghei berghei in mice was evaluated. ... indicated in the consistent increase in weight and slight increase in the PCV ... Key words: Chromolaena odorata, Cymbopogon citratus, anti-malarial .... This was prepared by determining both the percentage parasitaemia and the ..... Malaria vaccine: Multiple targets.

  20. Nigerian Journal of Biotechnology - Vol 21 (2010)

    African Journals Online (AJOL)

    Inhibition of Growth of Fungi Isolated From Deteriorating Melon Seed By Extracts of Punica Granatum and Cymbopogon Citratus · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. A Banso, A.G Jiya, 60-64 ...