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.

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

Anthelmintic activity of Cymbopogon citratus against Haemonchus contortus

Directory of Open Access Journals (Sweden)

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.

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.

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

Science.gov (United States)

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.

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

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.

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

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.

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

Directory of Open Access Journals (Sweden)

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.

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.

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

Directory of Open Access Journals (Sweden)

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.

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.

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

Directory of Open Access Journals (Sweden)

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.

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.

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 .

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.

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...

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

Directory of Open Access Journals (Sweden)

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.

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

Directory of Open Access Journals (Sweden)

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.

Antifungal activity of Cymbopogon citratus against Colletotrichum gloesporioides

Directory of Open Access Journals (Sweden)

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.

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

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

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.

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

Science.gov (United States)

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.

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

Directory of Open Access Journals (Sweden)

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.

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

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.

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

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)

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.

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...

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

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

Directory of Open Access Journals (Sweden)

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..

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.

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.

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

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.

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

Directory of Open Access Journals (Sweden)

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

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.

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

Directory of Open Access Journals (Sweden)

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

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

Directory of Open Access Journals (Sweden)

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

[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.

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.

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

Directory of Open Access Journals (Sweden)

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.

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

Directory of Open Access Journals (Sweden)

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.

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.

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

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.

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

Directory of Open Access Journals (Sweden)

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.

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.

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.

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.

[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.

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.

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.

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.

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.

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.

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

Directory of Open Access Journals (Sweden)

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.

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

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

Directory of Open Access Journals (Sweden)

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.

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

Directory of Open Access Journals (Sweden)

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.

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.

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.

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

Directory of Open Access Journals (Sweden)

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.

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

Directory of Open Access Journals (Sweden)

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.

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

Directory of Open Access Journals (Sweden)

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.

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.

Cymbopogon Species; Ethnopharmacology, Phytochemistry and the Pharmacological Importance

Directory of Open Access Journals (Sweden)

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.

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.

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

Directory of Open Access Journals (Sweden)

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.

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)

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)

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.

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.

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).

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

Directory of Open Access Journals (Sweden)

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.

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.

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

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

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

Science.gov (United States)

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.

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

Science.gov (United States)

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.

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...

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.

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

Science.gov (United States)

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.

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

OpenAIRE

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...

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 ...

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 ...

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

Directory of Open Access Journals (Sweden)

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

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

[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.

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

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

Directory of Open Access Journals (Sweden)

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

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.

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...

Quality of medicinal plants traditionally used in Sudan as affected by ionizing radiation treatments

Energy Technology Data Exchange (ETDEWEB)

Musa, H A. A. [Department of Botany and Agricultural Biotechnology, Faculty of Agriculture, University of Khartoum, Khartoum (Sudan)

2009-11-15

This investigation was conducted to study the effect of gamma-radiation doses of 5, 10 and 15 KGy on the microbial and chemical quality as well as antioxidant activity of nine medical plants from 8 plant species grown in Sudan. The plant materials were collected from the country-side of Khartoum State as well as from local markets. Plant parts were selected according to their traditional uses as medicinal plants. Irradiation treatment was carried out or dried ground samples using doses of 5,10, 15 KGy from experimental cobalt-60 gamma source. Plants extracts were prepared using 80% methanol. The control and irradiated samples were analyzed for total bacterial count (cfu/g), secondary compounds, tannin content, total phenol, and antioxidant activity. Tannins, flavonoids, glycosides, anthraquinones, saponin and phenols were evaluated through major compounds in extracts. The total bacterial count indicated that the non- irradiated samples of Trigonella foenum-graecum L., Cassia senna (pods), Cassia senna (leaves), Acacia nilotica L., Brassica nigra L. Koch, Lepidium sativum L., Cymbopogon citratus and Hibiscus sabdariffa L. were highly contaminated with bacteria. The sample of Cymbopogon schoenanthus L. showed a lower count of bacteria (9x10'' 3 Cfu/g), which did not exceed the acceptable level. The samples irradiated with 5, 10 and 15 KGy of gamma radiation dose had significantly lower bacterial counts than the non-irradiated control. The highest sensitivity to gamma rays at 5 KGy dose was observed in Trigonella foenum-graecum L. and Acacia nilotica L. while the lowest sensitivity was in Cymbopogon schoenanthus L. At 15 KGy dose Hibiscus sabdariffa L. and Cymbopogon citratus showed complete absence of microorganisms. The highest reduction in tannin content (mg/L catechin) due to irradiation with 15 KGy dose was observed in Cymbopogon citratus, followed by Cymbopogon schoenanthus L., Cassia senna L. leaves Acacia nilotica L. and Hibiscus sabdariffa L.. Irradiation

Quality of medicinal plants traditionally used in Sudan as affected by ionizing radiation treatments

International Nuclear Information System (INIS)

Musa, H. A. A.

2009-11-01

This investigation was conducted to study the effect of gamma-radiation doses of 5, 10 and 15 KGy on the microbial and chemical quality as well as antioxidant activity of nine medical plants from 8 plant species grown in Sudan. The plant materials were collected from the country-side of Khartoum State as well as from local markets. Plant parts were selected according to their traditional uses as medicinal plants. Irradiation treatment was carried out or dried ground samples using doses of 5,10, 15 KGy from experimental cobalt-60 gamma source. Plants extracts were prepared using 80% methanol. The control and irradiated samples were analyzed for total bacterial count (cfu/g), secondary compounds, tannin content, total phenol, and antioxidant activity. Tannins, flavonoids, glycosides, anthraquinones, saponin and phenols were evaluated through major compounds in extracts. The total bacterial count indicated that the non- irradiated samples of Trigonella foenum-graecum L., Cassia senna (pods), Cassia senna (leaves), Acacia nilotica L., Brassica nigra L. Koch, Lepidium sativum L., Cymbopogon citratus and Hibiscus sabdariffa L. were highly contaminated with bacteria. The sample of Cymbopogon schoenanthus L. showed a lower count of bacteria (9x10'' 3 Cfu/g), which did not exceed the acceptable level. The samples irradiated with 5, 10 and 15 KGy of gamma radiation dose had significantly lower bacterial counts than the non-irradiated control. The highest sensitivity to gamma rays at 5 KGy dose was observed in Trigonella foenum-graecum L. and Acacia nilotica L. while the lowest sensitivity was in Cymbopogon schoenanthus L. At 15 KGy dose Hibiscus sabdariffa L. and Cymbopogon citratus showed complete absence of microorganisms. The highest reduction in tannin content (mg/L catechin) due to irradiation with 15 KGy dose was observed in Cymbopogon citratus, followed by Cymbopogon schoenanthus L., Cassia senna L. leaves Acacia nilotica L. and Hibiscus sabdariffa L.. Irradiation

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%.

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 ...

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

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.

'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.

Developing eco-friendly biofungicide for the management of major seed borne diseases of rice and assessing their physical stability and storage life.

Science.gov (United States)

Naveenkumar, Ramasamy; Muthukumar, Arjunan; Sangeetha, Ganesan; Mohanapriya, Ramanathan

2017-04-01

Three plant oils (Cymbopogon citratus, Cymbopogon martini, and Pelargonium graveolens) were developed as EC formulations and tested for their physical stabilities. EC formulations (10EC, 20EC and 30EC) of C. citratus, C. martini and P. graveolens had emulsion stability, spontaneity property, heat and cold stability. EC formulated plant oils were screened against the major seed borne fungi of rice such as Curvularia lunata, Fusarium moniliforme, Bipolaris oryzae, and Sarocladium oryzae. The level of inhibition varied among the concentrations of EC formulations. Among the three EC formulations, that of C. citratus oil 30EC recorded 100% inhibition on the mycelial growth of test pathogens. In the blotter paper method, rice seeds treated with a formulation of C. citratus oil 30EC controlled the infection of C. lunata, F. moniliforme, B. oryzae and S. oryzae in rice seed to the tune of 66.0%, 60.4%, 66.0% and 69.1%, respectively. Seed soaking with formulation of C. citratus oil 30EC showed the highest percentage of normal seedlings, the lowest number of abnormal seedling and fresh ungerminated seeds when tested with the roll-towel method. Seed soaking with 30EC formulation of C. citratus oil increased seed germination, shoot length, root length and vigour of rice seedlings when tested with the plastic tray method. Transmission of pathogens from seed to seedling was reduced significantly by the 30EC formulation of C. citratus oil when tested with the plastic pot method. The effect of the storage life of the 30EC formulation of C. citratus oil showed that it had retained their antifungal effect till the end of the incubation period (120 days), and is able to inhibit the mycelial growth of all test pathogens to the 100% level. Copyright © 2017 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.

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.

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 ...

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 ...

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.

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.

(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.

PENGUJIAN BEBERAPA JENIS INSEKTISIDA NABATI TERHADAP KUTU BERAS (Sitophilus oryzae L

Directory of Open Access Journals (Sweden)

Muhammad Isnaini

2015-08-01

Full Text Available The purpose of this study first to determine whether or not capable of  natural insecticides to kill Sitophilus oryzae L and to determine effective of  natural insecticides to kill Sitophilus oryzae L. This type of research is an experimental research with quantitative descriptive and The data collection techniques used is the observation and documentation. The data analyzed with ANOVA analysis techniques followed by BJND test. Based on the comparison of the calculated F value contained in the ANOVA analysis is greater than the F table , either at the significant level of 5 % and the 1% significance level (79.57 > 2.67 / 4:43. Thus stated that H1 accepted and rejected H0. The results showed that the first, the natural insecticide able to kill Sitophilus oryzae L and mortality rate highest in Cymbopogon citratus treatment that is equal to 13.2 with the total percentage of mortality of 66%, both effective plant-based insecticides to kill Sitophilus oryzae L that leaves just Cymbopogon citratus (66% and Morinda citrifolia L (60%.The conclusions obtained from this study: First, some kind of  natural insecticide able to kill Sitophilus oryzae L,  second based on the results of the ANOVA analysis of all types of insecticides to kill Sitophilus oryzae L effectively, but if effectiveness was seen by the number of mortality up to 50 % or more, then just Cymbopogon citratus and Morinda citrifolia L.

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 ...

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...

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 ...

Antifungal activity and ultrastructural alterations in Pseudocercospora griseola treated with essential oils Atividade antifúngica e alterações ultraestruturais em Pseudocercospora griseola tratado com óleos essenciais

Directory of Open Access Journals (Sweden)

Julián Mauricio Ágredo Hoyos

2012-06-01

Full Text Available Pseudocercospora griseola, the etiologic agent of angular leaf spot of common bean (Phaseolus vulgaris, is an important disease in all bean-producing regions worldwide and may cause extremely high yield losses. The control of this disease is made more difficult by the pathogen's genetic variability and the inefficiency of fungicides. In this study, of 26 essential oils tested at different concentrations, 25 demonstrated efficiency in affecting the germination of strains 63-31 and 63-63 of the pathogen, reaching inhibition levels of between 80% and 100%. Cymbopogon citratus and Cymbopogon martinii inhibited conidia germination at all concentrations; Eugenia caryophyllata, Cinnamomum sp., Thymus vulgaris, Matricaria recutita, Cordia verbenacea, Origanum vulgare, Cymbopogon nardus, at 0.1 and 0.5%; and Zingiber officinale, Mentha arvensis, Chamaecyparis pisifera, Lavandula officinalis, Ocimum basilicum, Pimpinella anisum, Ocimum selloi, Baccharis dracunculifolia, Laurus nobilis, Citrus sinensis, Melaleuca alternifolia and Eucalyptus globulus, at 0.5%. The main constituents identified were cinnamaldehyde in Cinnamomum sp.; eugenol in E. caryophyllata; trans-β-farnesene in M. recutita; pulegone in C. verbenacea; thymol in T. vulgaris; geranial and neral in C. citratus, and geraniol in C. martini. Through transmission electron microscopy (TEM, it was verified that C. citratus, C. martini and E. caryophyllata presented direct fungitoxic action on P. griseola, causing severe damage to the cellular ultrastructure of the conidia, invalidating germination. These results indicated that essential oils are a promising alternative strategy for the control of angular leaf spot in bean, representing less risk to human health and the environment.Pseudocercospora griseola, agente etiológico da mancha angular do feijoeiro comum (Phaseolus vulgaris, é uma doença importante nas regiões produtoras de feijão em todo o mundo e pode causar perdas de produtividade

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.

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, ...

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 ...

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 ...

Extratos de plantas no controle de Rhipicephalus (Boophilus microplus (Canestrini, 1887 (Acari: Ixodidae em laboratório Plant extracts in control of Rhipicephalus (Boophilus microplus (Canestrini, 1887 (Acari: Ixodidae in laboratory

Directory of Open Access Journals (Sweden)

Sônia Maria Forti Broglio-Micheletti

2009-12-01

Full Text Available Extratos vegetais foram estudados com o objetivo de avaliar suas eficiências no controle de Rhipicephalus (Boophilus microplus (Canestrini, 1887 em laboratório. Fêmeas ingurgitadas de carrapato foram coletadas de bovinos e mantidas em placas de Petri. Foram utilizados extratos orgânicos alcoólicos 2% (peso/volume de sementes de Annona muricata L. (Annonaceae (graviola; flores de Syzygium malaccensis (L. (Myrtaceae (jambo; folhas de Cymbopogon citratus (DC. Stapf (Poaceae (capim-santo; folhas de Azadirachta indica A. Juss (Meliaceae (nim; e extrato hexânico na mesma concentração de A. indica (sementes. Os grupos-controle foram compostos por fêmeas sem tratamento e fêmeas tratadas com água destilada e esterilizada e dimetilsulfóxido (DMSO a uma concentração de 1%. O extrato de A. muricata apresentou o maior poder acaricida, com eficácia de 100%, seguido dos extratos de S. malaccensis (75 e 59,24% e A. indica (65 e 38,49%. Houve 100% de redução na eclosão das larvas quando se utilizou o extrato de sementes de A. muricata.Plant extracts were studied to evaluate its efficiency in the control of Rhipicephalus (Boophilus microplus (Canestrini, 1887 in laboratory. Engorged female ticks were collected from the cattle, kept in Petri dishes. Organic alcoholic extracts 2% (weight/volume were used: seeds of Annona muricata L. (Annonaceae (soursop; flowers of Syzygium malaccensis (L. (Myrtaceae (iamb, leaves of Cymbopogon citratus (DC. Stapf (Poaceae (holy grass, leaves of Azadirachta indica A. Juss (Meliaceae (neem and hexane extract 2% (weight/volume of A. indica (seeds. The control groups consisted of untreated females and females treated with distilled water and sterile and dimethylsulfoxide (DMSO a concentration of 1%. The extract of A. muricata (seed had the highest mortality with acaricide activity and 100% efficacy followed by extracts of S. malaccensis (75 and 59.24% and A. indica (65 and 38.49%. The seed extract of A. muricata

Estudo da concordância das citações de uso e importância das espécies e famílias utilizadas como medicinais pela comunidade do bairro Ponta Grossa, Porto Alegre, RS, Brasil

Directory of Open Access Journals (Sweden)

Giovana Secretti Vendruscolo

2006-06-01

Full Text Available Ferramentas para quantificar dados etnobotânicos estão sendo usadas como complementares aos levantamentos sobre a utilização de plantas por populações. Neste trabalho são utilizadas técnicas para avaliar a concordância das citações de uso e a importância das espécies e famílias para as 51 pessoas entrevistadas no bairro Ponta Grossa, Porto Alegre, Rio Grande do Sul. Para tal, foram utilizados os cálculos de Valor de Uso (UV e a porcentagem corrigida de Concordância quanto aos Usos Principais (CUPc para as 142 espécies mencionadas no levantamento. As espécies Aloe arborescens Mill., Citrus × aurantium L., Achyrocline satureioides (Lam. DC., Foeniculum vulgare Mill, Eugenia uniflora L., Cunila microcephala Benth., Citrus limon (L. Osveck, Plectranthus barbatus Andrews, Cymbopogon citratus (DC. Stapf, Psidium guajava L., Artemisia absinthium L., Ocimum basilicum L., Plantago tomentosa Lam., Rosmarinus officinalis L., Persea americana Mill., Aloysia citrodora Palau, Sambucus australis Cham. & Schltdl., Cuphea carthagenensis (Jacq. J.F. Macbr., Petroselinum crispum (Mill. Nyman ex A.W. Hill, Ocimum selloi Benth. e Tanacetum vulgare L., nesta ordem de Valor de Uso, foram consideradas como as mais importantes para a população estudada. As famílias mais importantes foram Asphodelaceae, Caprifoliaceae, Rutaceae e Lythraceae. Para o cálculo da porcentagem a corrigida de Concordância quanto aos Usos Principais (CUPc foram consideradas como espécies principais as que apresentaram valores acima de 24%: Eugenia uniflora, Achyrocline satureioides, Psidium guajava, Cunila microcephala, Plectranthus barbatus, Citrus × aurantium, Citrus limon, Cymbopogon citratus, Punica granatum L., Sechium edule (Jacq. Sw., Sphagneticola trilobata (L. Pruski, Aloysia citrodora, Foeniculum vulgare, Plectranthus neochilus Schltr., Artemisia absinthium, Lippia alba (Mill. N.E. Br., Mikania laevigata Sch. Bip ex Baker, Aloe arborescens e Petroselinum

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.

Natural Plant Oils and Terpenes as Protector for the Potato Tubers against Phthorimaea operculella Infestation by Different Application Methods

Directory of Open Access Journals (Sweden)

Aziza Sharaby

2014-06-01

Full Text Available For protecting potato tubers from the potato tuber moth (PTM infestation during storage, different concentrations of ten natural plant oils and three commercial monoterpnes were tested, some as fumigants or dusts against adults or dusts against neonate larvae, while others as sprays on the gunny sacks in which potato tubers were stored. Tuber damage indices as well as persistence indices for tested materials were assessed. Vapors of Cymbopogon citratus, Myristica fragrans (nutmag, Mentha citrata and a-Ionone (monoterpene caused a highly significant reductions in the life span of exposed moths as well as in new adult offsprings. Other tested oils as Cinnamonium zeylanicum, Myristica. fragrans (Mace and Pelargonium graveolens caused a insignificant effect. There was no significant effect of the tested vapors on egg hatchability, except in case of oils of C. citratus, M. fragrans (nutmag and M. tragrans(Mace oil which caused high reduction in egg hatchability. According to the values of damage indices, the most effective oil vapors were arranged ascendingly as follows: Myristica (nutmag < Cymbopogon < Mentha < a - Ionone. Dusting potato tubers with 1% conc., (mixed with talcum powder of Myristica, Mentha, Cymbopogons oils and a-Ionone (monoterpene caused high reduction in egg deposition, adult emergence as well as percentage of penetrated larvae of PTM. According to their damage indices, Cymbopogon and ά-Ionone were the most protective oils, followed by Myristica and Mentha. Spraying gunnysacks with 1% conc., of the aforementioned natural oils separately elicited high reduction in PTM progeny; while their combinations did not elicit any significant synergistic effect. According to their tuber damage indices, it was found that Cymbopogon oil alone or mixed with Myristica oil showed the best protective effect, followed by Myristica oil alone and Mentha oil mixed with Cymbopogon oil. Assessment of the persistence index of various tested materials

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, ...

Potentials of two bio-pesticides in the control of some field insect ...

African Journals Online (AJOL)

A field experiment was carried out to determine the predominate order of insects associated with Bambara groundnut and to compare the efficacy of aqueous leaf extracts of Jatropha (Jatropha curcas) and lemon grass (Cymbopogon citratus), used as bio-pesticides in controlling some field insect pests of Bambara ...

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 ...

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, ...

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; ...

In vitro effect of seven essential oils on the reproduction of the cattle tick Rhipicephalus microplus

Directory of Open Access Journals (Sweden)

Rafael Pazinato

2016-11-01

Full Text Available The acaricidal effect of seven essential oils was examined in vitro against the cattle tick (Rhipicephalus microplus. Engorged female ticks were manually collected in farms of Southern Brazil and placed into petri dishes (n = 10 in order to test the following oils: juniper (Juniperus communis, palmarosa (Cymbopogon martinii, cedar (Cedrus atlantica, lemon grass (Cymbopogon citratus, ginger (Zingiber officinale, geranium (Pelargonium graveolens and bergamot (Citrus aurantium var bergamia at concentrations of 1%, 5%, and 10% each. A control group was used to validate the tests containing Triton X-100 only. Treatment effectiveness was measured considering inhibition of tick oviposition (partial or total, egg’s weight, and hatchability. C. martinii, C. citratus and C. atlantica essential oils showed efficacy higher than 99% at all concentrations tested. In addition, J. communis, Z. officinale, P. graveolens, and C. aurantium var bergamia oils showed efficiency ranging from 73% to 95%, depending on the concentration tested, where higher concentrations showed greater efficacy. It was concluded that essential oils can affect tick reproduction in vitro by inhibiting oviposition and hatchability.

Fungitoxic effect of concentrations of essential oils on Colletotrichum gloeosporioides, isolated from the passion fruit

Directory of Open Access Journals (Sweden)

Ismail Teodoro Souza Júnior

2009-09-01

Full Text Available This study aimed to evaluate the effect of different concentrations of essential oils on the fungus Colletotrichum gloeosporioides. The essential oils were obtained from shoots of the plants Lippia sidoides, Ocimum gratissimum, Lippia citriodora, Cymbopogon citratus and Psidium guayava var. pomifera. After the incorporation of oil in water-agar and PDA medium, in concentrations of 1μL/mL, 3μL/mL 5μL/mL and 10μL/mL and witness at 0μL/mL (oil/the culture medium, the inhibitions of conidia germination and mycelial growth, respectively, were evaluates. The results showed that from the concentration of 1μL/mL, essential oils of all plant species had an effect on conidia germination, with an inhibition of 100%. The species Lippia sidoides, Ocimum gratissimum, Lippia citriodora and Cymbopogon citratus inhibited the growth of the fungus mycelium by 100%. The oil of Psidium guayava var. pomifera had progressive control over the mycelium of C. gloeosporioides, in accordance with the increase in concentrations of essential oil.

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.

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.

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

Directory of Open Access Journals (Sweden)

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.

Ethnobotanical survey of medicinal plants marketed in the municipality of Uruará, Pará, Brazil

Directory of Open Access Journals (Sweden)

Reinaldo Lucas Cajaiba

2016-02-01

Full Text Available The present study aimed to perform an ethnobotanical survey of medicinal plants marketed by the population of the municipality of Uruará, Pará, and its main districts. The respondents mentioned 63 species distributed in 36 botanical families. The most representative families were Lamiaceae, Asteraceae, Fabaceae and Rutaceae. The species with the highest Use Value were capim cidreira (Cymbopogon citratus, UV = 0.90, mastruz (Chenopodium ambrosioides, UV = 0.83 and hortelã (Mentha sp., UV = 0.79, while capim cidreira (Cymbopogon citratus and picão (Bidens pilosa had a higher indicator value, and were indicated as a tranquilizer/painkiller and for treating kidney disease, respectively. Among the main disorders treated with medicinal plants, diseases of the digestive system, infections/inflammations, colds and respiratory system diseases were the most cited. There was no significant difference between the number of species mentioned and the number of individuals per family or the distance of households to the urban zone. There was also no difference between the number of species mentioned and education level. Most medicinal plants marketed in the municipality are herbs, leaves are the most used parts and the most common form of preparation is tea.

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

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 ...

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 ...

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.

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

Efeito repelente de azadiractina e óleos essenciais sobre Aphis gossypii Glover (Hemiptera: Aphididae em algodoeiro Repellent effect of azadirachtin and essential oils on Aphis gossypii Glover (Hemiptera: Aphididae in cotton plants

Directory of Open Access Journals (Sweden)

Lígia Helena de Andrade

2013-09-01

Full Text Available A repelência de inseticidas botânicos tem se destacado como uma tática promissora no controle alternativo de pragas agrícolas e urbanas, podendo ser um dos componentes do manejo integrado de pragas. Objetivou-se com este trabalho identificar a repelência de inseticidas botânicos sobre fêmeas ápteras de Aphis gossypii Glover. Testes com chance de escolha foram realizados com discos de folha de algodoeiro, imersos nas caldas dos inseticidas e testemunha (água destilada com DMSO a 2%. Utilizou-se azadirachtina (0,075% e os óleos essenciais de Piper hispidinervum CDC, P. aduncum L., Cymbopogon winterianus (L., C. citratus (D.C. Stapf, Foeniculum vulgare Mill, Syzygium aromaticum (L. Merrill e Perry, Cinnamomum zeylanicum Blume, Schinus terebinthifolius Raddi e Chenopodium ambrosioides L. na concentração de 0,05%. C. citratus, C. winterianus, P. aduncum, S. terebinthifolius, azadirachtina e C. zeylanicum apresentaram os maiores percentuais de repelência, 100; 84; 66,67; 64; 60,87 e 48% respectivamente e reduziram a produção de ninfas em 100; 92; 42,9; 87,5; 80,65 e 89,74%, apresentando resultados significativos pelo teste do χ2 ao nível de 10% de probabilidade. Nos testes com F. vulgare (χ2 = 3,66, P = 0,05 as fêmeas de A. gossypii foram atraídas significativamente para os discos tratados e ocorreu um aumento na produção de ninfas nos resultados obtidos para F. vulgare (χ2 = 5,87, P = 0,02 e C. ambrosioides (χ2 = 14,31, P = 0,001.The repellence of botanical insecticides has emerged as a promising technique in the alternative control of urban and agricultural pests, being seen as one component of integrated pest management. The aim of this work was to identify the repellence of botanical insecticides on apterous females of Aphis gossypii Glover. Random-choice tests were carried out with discs from the leaves of cotton plants immersed in insecticide solution and in a control (distilled water with 2% DMSO. Azadirachtin was used

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 ...

Effect of essential oils of medicinal plants on leaf blotch in Tanzania grass Efeito de óleos essenciais de plantas medicinais sobre a helmintosporiose do capim Tanzânia

Directory of Open Access Journals (Sweden)

Gil Rodrigues dos Santos

2013-09-01

Full Text Available Leaf spots caused by phyto-pathogenic fungi, can reduce the production of forage plants. The essential oils of medicinal plants have antimicrobial potential. The objective here was to evaluate the fungotoxicity in vitro of the essential oils of lemongrass (Cymbopogon citratus (DC. Stapf (Poaceae, citronella (Cymbopogon nardus (L. Rendle (Poaceae, lemon balm (Lippia alba (Mill. NE Br ex Britton & P. Wilson (Verbenaceae and peppermint (Mentha piperita L. (Lamiaceae on the fungus Helminthosporium sp. and the in vivo effect of these oils and of commercial neem oil (Azadirachta indica A. Juss. (Meliaceae on leaf blotch in Panicum maximum Jacq. cv. Tanzania-1. The mycelial growth of the fungus was evaluated over five periods (2; 4; 6; 8 and 10 days from incubation and with five concentrations of essential oils (C1 = 250 ppm; C2 = 500 ppm; C3 = 750 ppm; C4 = 1,000 ppm e C5 = 1,250 ppm. As an alternative control, the preventative and curative effect on leaf blotch of five oil-based treatments were evaluated: lemongrass, citronella, lemon balm, peppermint and neem in four concentrations (2,500; 5,000; 7,500 and 10,000 ppm. The essential oils of lemongrass and citronella were the most effective in reducing mycelial growth of Helminthosporium sp. With the essential oil of lemongrass, the pathogen presented the highest growth concentration (1.250 ppm. The results obtained showed that all the essential oils and concentrations tested presented a preventive and curative effect, reducing the severity of leaf blotch.Manchas foliares, causadas por fungos fitopatogênicos, podem reduzir a produção de forrageiras. Óleos essenciais de plantas medicinais apresentam potencial antimicrobiano. Objetivou-se avaliar a fungitoxicidade in vitro dos óleos essenciais de capim-limão (Cymbopogon citratus (DC. Stapf (Poaceae, citronela (Cymbopogon nardus (L. Rendle (Poaceae, erva-cidreira (Lippia alba (Mill. N.E. Br. ex Britton & P. Wilson (Verbenaceae e hortel

Citral reduces nociceptive and inflammatory response in rodents

OpenAIRE

Quintans-Júnior, Lucindo J.; Guimarães, Adriana G.; Santana, Marilia T. de; Araújo, Bruno E.S.; Moreira, Flávia V.; Bonjardim, Leonardo R.; Araújo, Adriano A. S.; Siqueira, Jullyana S.; Antoniolli, Ângelo R.; Botelho, Marco A.; Almeida, Jackson R. G. S.; Santos, Márcio R. V.

2011-01-01

Citral (CIT), which contains the chiral enantiomers, neral (cis) and geranial (trans), is the majority monoterpene from Lippia alba and Cymbopogon citratus. The present study aimed to evaluate CIT for antinociceptive and anti-inflammatory activities in rodents. Antinociceptive and anti-inflammatory effects were studied by measuring nociception through acetic acid and formalin tests, while inflammation was verified by inducing peritonitis and paw edema with carrageenan. All tested doses of CIT...

Ethnobotanical survey of medicinal plants marketed in the municipality of Uruará, Pará, Brazil

Directory of Open Access Journals (Sweden)

Reinaldo Lucas Cajaiba

2016-02-01

Full Text Available http://dx.doi.org/10.5007/2175-7925.2016v29n1p115 The present study aimed to perform an ethnobotanical survey of medicinal plants marketed by the population of the municipality of Uruará, Pará, and its main districts. The respondents mentioned 63 species distributed in 36 botanical families. The most representative families were Lamiaceae, Asteraceae, Fabaceae and Rutaceae. The species with the highest Use Value were capim cidreira (Cymbopogon citratus, UV = 0.90, mastruz (Chenopodium ambrosioides, UV = 0.83 and hortelã (Mentha sp., UV = 0.79, while capim cidreira (Cymbopogon citratus and picão (Bidens pilosa had a higher indicator value, and were indicated as a tranquilizer/painkiller and for treating kidney disease, respectively. Among the main disorders treated with medicinal plants, diseases of the digestive system, infections/inflammations, colds and respiratory system diseases were the most cited. There was no significant difference between the number of species mentioned and the number of individuals per family or the distance of households to the urban zone. There was also no difference between the number of species mentioned and education level. Most medicinal plants marketed in the municipality are herbs, leaves are the most used parts and the most common form of preparation is tea.

In vitro Antifungal Activity of Various Local Plant Extracts in the Control of Phoma sorghina (Sacc. Boerema et al. and Colletotrichum graminicola (Ces. Wilson, as Sorghum Seed Mold Pathogen in Burkina Faso

Directory of Open Access Journals (Sweden)

Bonzi, S.

2012-01-01

Full Text Available The use of phytosanitary products is becoming increasingly restricted, due to their high cost, as well as the unavailability of certain products on the local market and their damaging effects on the environment and health. These different reasons motivated the search for alternative solutions to the use of synthetic pesticides. On this basis, we took on the task of evaluating the anti-fungal effectiveness of aqueous plant extracts from Balanites aegyptiaca, Cymbopogon citratus, Cassia occidentalis and Portulaca oleracea. These extracts, at 30% concentration, were obtained after different maceration periods (6, 12, 24 and 48 hours and tested in vitro against Colletotrichum graminicola and Phoma sorghina. The effect of the extracts on the mycelium growth of various fungi, when evaluated 10 days after incubation (DAI, shows that extracts of C. citratus, B. aegyptiaca, P. oleracea and C. occidentalis inhibit the growth of C. graminicola by 100%, 65%, 43% and 38%, respectively. The extract of C. citratus prevents the development of C. graminicola, regardless of the maceration period. This extract produces a greater inhibitory effect than the fungicide Calthio DS (20% Lindane and 25% Thirame. Compared to P. sorghina, inhibition percentages of 100, 72 and 16 were recorded for extracts of C. citratus, P. oleracea and C. occidentalis. However, extracts of C. citratus (macerated for 24 and 48 hours and extract of P. oleracea (macerated for 48 hours were more effective than the other extracts.

A Weibull model to describe antimicrobial kinetics of oregano and lemongrass essential oils against Salmonella Enteritidis in ground beef during refrigerated storage.

Science.gov (United States)

de Oliveira, Thales Leandro Coutinho; Soares, Rodrigo de Araújo; Piccoli, Roberta Hilsdorf

2013-03-01

The antimicrobial effect of oregano (Origanum vulgare L.) and lemongrass (Cymbopogon citratus (DC.) Stapf.) essential oils (EOs) against Salmonella enterica serotype Enteritidis in in vitro experiments, and inoculated in ground bovine meat during refrigerated storage (4±2 °C) for 6 days was evaluated. The Weibull model was tested to fit survival/inactivation bacterial curves (estimating of p and δ parameters). The minimum inhibitory concentration (MIC) value for both EOs on S. Enteritidis was 3.90 μl/ml. The EO concentrations applied in the ground beef were 3.90, 7.80 and 15.60 μl/g, based on MIC levels and possible activity reduction by food constituents. Both evaluated EOs in all tested levels, showed antimicrobial effects, with microbial populations reducing (p≤0.05) along time storage. Evaluating fit-quality parameters (RSS and RSE) Weibull models are able to describe the inactivation curves of EOs against S. Enteritidis. The application of EOs in processed meats can be used to control pathogens during refrigerated shelf-life. Copyright © 2012 Elsevier Ltd. All rights reserved.

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.

Bioactive natural constituents from lemongrass tea and erythropoiesis boosting effects: potential use in prevention and treatment of anemia.

Science.gov (United States)

Ekpenyong, Christopher E; Daniel, Nyebuk E; Antai, Atim B

2015-01-01

This study assessed the effects of lemongrass (Cymbopogon citratus) tea on hematologic indices in human volunteers. One hundred five subjects (55 men and 50 women), aged 18 to 35 years, were randomly assigned to groups set to orally receive infusion prepared from 2, 4, or 8 g of C. citratus leaves once daily for 30 days. Assessment of hematologic indices (hemoglobin concentration [Hb], packed cell volume [PCV], red blood cell [RBC] count, mean cell Hb [MCH], mean cell volume [MCV], mean cell Hb concentration [MCHC], total white blood cell [WBC-total] and differentials, and platelets) were performed 1 day before (baseline), and at 10 (acute) and 30 days (subchronic phase) after the initiation of treatment. Results obtained on days 10 and 30 were compared with baseline values. Infusions prepared from C. citratus leaf powder, which tested positive for tannins, saponins, alkaloids, flavonoids, macro- and micronutrients, significantly increased PCV, Hb, and RBC (P<.05) in all subjects, particularly in the subchronic phase of the study. MCH, MCV, and MCHC were not significantly different from baseline values in both the sexes. WBCs and differentials significantly decreased (P<.05) with the exception of neutrophils and lymphocytes, which significantly increased in some or all groups (P<.05), respectively. C. citratus leaf infusion appears to exert an erythropoiesis boosting effect, likely due to some nutritional constituents and its antioxidant and pharmacologic properties.

Caracterização química e efeito inibitório de óleos essenciais sobre o crescimento de Staphylococcus aureus e Escherichia coli Chemical ckaracterization and inhibitory effect of essential oils on the growth of Staphylococcus aureus and Escherichia coli

Directory of Open Access Journals (Sweden)

Alcilene de Abreu Pereira

2008-06-01

Full Text Available Objetivou-se avaliar o efeito inibitório dos óleos essenciais de Cymbopogon citratus (capim-limão, Origanum vulgare (orégano e Syzygium aromaticum (cravo-da-índia; os experimentos foram realizados com as bactérias Staphylococcus aureus e Escherichia coli, importantes patógenos causadores de contaminações em queijos e outros alimentos. Para quantificação e identificação dos constituintes químicos dos óleos, utilizou-se um cromatógrafo gasoso acoplado a um espectrômetro de massa. Os resultados dos testes in vitro, os óleos essenciais de C. citratus, O. vulgare e S. aromaticum promoveram efeito inibitório sobre as bactérias S. aureus e E. coli, porém o S. aromaticum apresentou melhor formação de halo de inibição nas menores concentrações. Para o efeito sinergístico dos óleos sobre as bactérias não foram observadas diferenças quando comparados com o efeito individual dos mesmos. Foi possível verificar que os óleos possuem efeito inibitório sobre os microrganismos estudados, sendo, portanto uma alternativa no controle microbiológico de alimentos.With the aim of evaluating the inhinibitory effect of the Cymbopogon citratus (lemon grass, Origanun vulgare (oregano and Syzygium aromaticum (clove, experiments were performed in laboratories, with the Staphylococcus aureus, Escherichia coli bacteria, important pathogenics which contaminate cheese and other foods. For the oil chemical constitutions quantification and identification, the gas chromatography attached mass spectrometry to a was used. In the results in vitro test, the C. citratus, O. vulgare and S. aromaticum essential oils presented antimicrobian activity over S. aureus and E. coli bacteria, however, S. aromaticum presented better formation of inhibition halo in smaller concentrations. For the oil synergetic effect over bacteria and fungi, no significant difference was noticed when compared to their own individual effect. It was possible to verify that the

Insecticidal Activity of Some Traditionally Used Ethiopian Medicinal Plants against Sheep Ked Melophagus ovinus

OpenAIRE

Gemeda, Negero; Mokonnen, Walelegn; Lemma, Hirut; Tadele, Ashenif; Urga, Kelbessa; Addis, Getachew; Debella, Asfaw; Getachew, Mesaye; Teka, Frehiwot; Yirsaw, Kidist; Mudie, Kissi; Gebre, Solomon

2014-01-01

Twelve medicinal plants and a commercially used drug Ivermectin were examined for insecticidal activity against Melophagus ovinus sheep ked at different time intervals using in vitro adult immersion test. The findings show that at 3.13 µL/mL, 6.25 µL/mL and 12.5 µL/mL concentration of Cymbopogon citratus, Foeniculum vulgare and Eucalyptus globulus essential oils respectively, recorded 100% mortalities against M. ovinus within 3 hour of exposure. Significantly higher insecticidal activity of e...

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

Science.gov (United States)

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

2017-01-01

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 Staphylococcus aureus , Escherichia coli , Pseudomonas aeruginosa , Acinetobacter baumannii , and 30 clinical isolates of multidrug-resistant A. baumannii (MDR- A. baumannii ). Agar diffusion, minimum inhibitory concentration, and minimum bactericidal concentration (MBC) were employed for the determination of bactericidal activity of water distilled medicinal plants. Tea tree oil ( Melaleuca alternifolia ) was used as positive control in this study. The results indicated the volatile oil extracted from cinnamon exhibited potent antibacterial activity against the most common human pathogens, S. aureus , E. coli , P. aeruginosa , and A. baumannii . Most of volatile oil extracts were less effective against non-fermentative bacteria, P. aeruginosa . In addition, volatile oil extracted from cinnamon, clove, and tree basil possessed potent bactericidal activity against MDR- A. baumannii with MBC 90 of 0.5, 1, and 2 mg/mL, respectively. The volatile oil extracts would be useful as alternative natural product for the treatment of the most common human pathogens and MDR- A. baumannii infections.

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%).

Toxicity of Anethole and the Essential Oils of Lemongrass and Sweet Marigold to the Parasitic Mite Varroa destructor and Their Selectivity for Honey Bee (Apis mellifera Workers and Larvae

Directory of Open Access Journals (Sweden)

Qodratollah Sabahi

2018-01-01

Full Text Available This study examined the toxicity of anethole and that of the essential oils of lemongrass (Cymbopogon citratus and sweet marigold (Tagetes lucida to the mite Varroa destructor and to honey bee workers and larvae. Anethole was the most toxic compound to V. destructor (LC50: 304.9 μg/ml, whereas Tagetes oil was the least toxic (LC50: 1256.27 μg/ml. The most and least toxic compounds to worker bees were anethole and Tagetes oil with LD50s of 35942 and 85381 μg/ml, respectively. For larvae, Tagetes oil was the most toxic compound (LD50: 9580.7 μg/ml and anethole the least toxic (LD50: 14518.0 μg/ml. Anethole and Cymbopogon oil had the highest selectivity ratios. The expression of AChE, a gene that regulates the production of acetyl cholinesterase, a detoxifying enzyme, was not altered in bees treated with the plant compounds at 48 h post-treatment. This study showed that anethole and Cymbopogon oil have potential for controlling Varroa mites and seem to be relatively safe for larvae and adult honey bees.

WELFARE OF BROILERS INGESTING A PRE-SLAUGHTER HYDRIC DIET OF LEMON GRASS

Directory of Open Access Journals (Sweden)

AFB Royer

2015-09-01

Full Text Available ABSTRACTThe pre-slaughter period is considered critical in broiler production. Several factors contribute to increase the birds' stress, such as handling, harvesting, and transportation, negatively affecting their welfare. This study aimed at evaluating the addition of lemon grass (Cymbopogon citratusStapf to the drinking water of broilers during the pre-slaughter period on their behavior, blood cortisol, and surface temperature. The study was carried out at the experimental farm of the Federal University of Grande Dourados (UFGD, Dourados, MS, Brazil. In total, 2594 broilers were distributed according to a completely randomized experimental design, in a 3x2x2 factorial arrangement, with four replicates per treatment. Treatments consisted of three different lemon grass levels (Cymbopogon citratus Stapf used in the form of an infusion (0, 0.1, and 5 g per L of water, sex (male or female, and genetic strain (Ross(r 308 or Cobb(r 500. The infusion was offered when birds were 42 days old. On that day, blood was collected for blood cortisol level determination, broiler surface temperature was recorded, and an ethogram was applied to register broiler behavior. Blood cortisol level and broiler surface temperature were not affected by treatments (p>0.05. The behavior of beak opening was different between the genetic strains (p<0.05, being more frequent in Ross(r 308 broilers. Lemon grass water content did not affect broilers' surface temperature when consumed during the pre-slaughter period.

Toxic effects of essential plant oils in adult Sitophilus oryzae (Linnaeus (Coleoptera, Curculionidae

Directory of Open Access Journals (Sweden)

Andréa Roveré Franz

2011-03-01

Full Text Available Toxic effects of essential plant oils in adult Sitophilus oryzae (Linnaeus (Coleoptera, Curculionidae. Stored grains are subject to losses in quality nutritional value and in sanitation from the time they are stored to the time they are consumed. Botanical insecticides may offer an alternative solution for pest control. The objective was to test the insecticidal properties of the essential oils of Cymbopogon citratus (leaf, Zingiber officinale (root and Mentha sp. (leaf. The efficacy of these oils was tested to control the rice weevil, S. oryzae, using hydrodistillation. Chemical analysis of the essential oils was carried out by gas chromatography. Major components of C. citratus were geranial (48% and neral (31%, of Z. officinale were α-zingibereno (13%, geranial (16%, neral (10% and α-farneseno (5% and of Mentha sp. was menthol (92%. Bioassays were carried out by fumigation and topical application. In topical application assays, the essential oil of C. citratus had greater toxicity (LC50 0.027 µL mL-1 and shorter exposure time than the oils of the other two plants. After 24 h and 48 h, 70% and 100% mortality of S. oryzae occurred, respectively. In fumigation assays, essential oil of Z. officinale had a lower LC50 (1.18 µL cm-2 and 70% mortality after 24 h exposure. Therefore, we recommend the use of essential oils of C. citratus and Z. officinale to control the rice weevil S. oryzae.

Larvicidal Activity of essential oils from Brazilian plants against Aedes aegypti L.

Directory of Open Access Journals (Sweden)

Eveline Solon Barreira Cavalcanti

2004-08-01

Full Text Available Aedes aegypti L. is the major vector of dengue fever, an endemic disease in Brazil. In an effort to find effective and affordable ways to control this mosquito, the larvicidal activities of essential oils from nine plants widely found in the Northeast of Brazil were analyzed by measurement of their LC50. The essential oils were extracted by steam distillation and their chemical composition determined by GL-chromatography coupled to mass spectroscopy. The essential oils from Cymbopogon citratus and Lippia sidoides, reported in the literature to have larvicidal properties against A. aegypti, were used for activity comparison. The results show that Ocimum americanum and Ocimum gratissimum have LC50 of 67 ppm and 60 ppm respectively, compared to 63 ppm for L. sidoides and 69 ppm for C. citratus. These results suggest a potential utilization of the essential oil of these two Ocimum species for the control of A. aegypti.

Improved delivery of the anticancer agent citral using BSA nanoparticles and polymeric wafers

Directory of Open Access Journals (Sweden)

White B

2017-12-01

Full Text Available Benjamin White,1 Anna Evison,1 Eszter Dombi,1 Helen E Townley1,2 1Nuffield Department of Obstetrics and Gynaecology, Women’s Centre, John Radcliffe Hospital, 2Department of Engineering Science, Oxford University, Oxford, UK Abstract: Rhabdomyosarcoma (RMS is the most common soft tissue sarcoma in children, with a 5-year survival rate of between 30 and 65%. Standard treatment involves surgery, radiation treatment, and chemotherapy. However, there is a high recurrence rate, particularly from locoregional spread. We investigated the use of the natural compound citral (3,7-dimethyl-2,6-octadienal, which can be found in a number of plants, but is particularly abundant in lemon grass (Cymbopogon citratus oil, for activity against immortalized RMS cells. Significant cancer cell death was seen at concentrations above 150 μM citral, and mitochondrial morphological changes were seen after incubation with 10 μM citral. However, since citral is a highly volatile molecule, we prepared albumin particles by a desolvation method to encapsulate citral, as a means of stabilization. We then further incorporated the loaded nanoparticles into a biodegradable polyanhydride wafer to generate a slow release system. The wafers were shown to degrade by 50% over the course of 25 days and to release the active compound. We therefore propose the use of the citral-nanoparticle-polymer wafers for implantation into the tumor bed after surgical removal of a sarcoma as a means to control locoregional spread due to any remaining cancerous cells. Keywords: citral, nanoparticle, wafer, biodegradable, mitochondria, toroidal, cancer, rhabdomyosarcoma, Cymbopogon citratus

Plantas medicinais utilizadas na comunidade urbana de Muribeca, Nordeste do Brasil

Directory of Open Access Journals (Sweden)

Gisele Lopes de Oliveira

2010-06-01

Full Text Available As modernas condições de vida das comunidades urbanas comprometem o uso e transmissão do conhecimento tradicional sobre plantas medicinais. Neste trabalho foi verificada a alteração provocada por treinamento sobre plantas medicinais de um grupo de seis moradoras da comunidade de Muribeca (Jaboatão do Guararapes, PE, comparando-as com vinte moradores com conhecimento adquirido tradicionalmente. A partir de 26 entrevistas semi-estruturadas foram calculados o Fator de Consenso dos Informantes (FCI e a Importância Relativa (IR das plantas citadas pelos dois grupos. As moradoras com treinamento no uso e manipulação citaram 70 espécies, das quais Petiveria alliacea L. e Ocimum selloi Benth. apresentaram os maiores valores de IR (2,0 e 1,6; os sistemas corporais mais indicados e respectivos FCI foram: doenças infecciosas (1,0, doenças das glândulas endócrinas, da nutrição e metabolismo (0,9 e do sistema osteomuscular e tecido conjuntivo (0,89. Os moradores sem treinamento citaram 55 espécies, com maiores valores de IR para Cymbopogon citratus (DC Stapf (2,0, Lippia alba (Mill. N.E. Br. (2,0 e Mentha x villosa Huds. (1,8; os sistemas corporais mais indicados e respectivos FCI foram: doenças parasitárias (1,0, transtornos dos sistemas nervoso (0,79 e gastrintestinal (0,72. As espécies citadas são semelhantes, mas o treinamento influenciou a importância relativa e indicações de usos das plantas.Modern ways of life in urban communities have altered the use and popular transmission of knowledge about medicinal plants. This study evaluated the changes induced by training in medicinal plants in a group of female residents of the urban community of Muribeca (Jaboatão do Guararapes, Pernambuco, comparing them with other community members who have traditionally acquired knowledge. Semi-structured interviews were employed. Informant Consensus Factor (FIC and Relative Importance (RI of each species cited by the two groups were calculated

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

Directory of Open Access Journals (Sweden)

Amornrat Intorasoot

2017-06-01

Full Text Available Aim:\tTo 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, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii and thirty clinical isolates of multidrug-resistant A. baumannii (MDR-A. baumannii. Methods:\tAgar diffusion, minimal inhibitory concentration (MIC and minimal bactericidal concentration (MBC were employed for determination of bactericidal activity of water distillated medicinal plants. Tea tree oil (Melaleuca alternifolia was used as positive control in this study. Results:\tThe results indicated the volatile oil extracted from cinnamon exhibited potent antibacterial activity against the most common human pathogens, S. aureus, E. coli, P. aeruginosa and A. baumannii. Most of volatile oil extracts were less effective against non-fermentative bacteria, P. aeruginosa. In addition, volatile oil extracted from cinnamon, clove and tree basil possessed potent bactericidal activity against MDR-A. baumannii with MBC90 of 0.5, 1 and 2 mg/mL, respectively. Conclusions: The volatile oil extracts would be useful as alternative natural product for treatment of the most common human pathogens and MDR-A. baumannii infections. [J Complement Med Res 2017; 6(2.000: 218-222

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 ...

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.

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...

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

Directory of Open Access Journals (Sweden)

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.

Levantamento etnobotânico de plantas medicinais na cidade de Ipameri - GO Ethnobotanical survey of medicinal plants in Ipameri City - Goiás State

Directory of Open Access Journals (Sweden)

M.R. Zucchi

2013-01-01

Full Text Available Os objetivos deste trabalho foram: identificar as espécies vegetais utilizadas com fins medicinais pela comunidade de Ipameri (Estado de Goiás; investigar as preferências com relação à produção e comercialização dessas plantas; e diagnosticar o perfil de gênero e as faixas etárias e salariais de seus usuários. Para isso, foram realizadas entrevistas estruturadas com 200 famílias da cidade e coletadas as plantas visando-se a sua correta identificação. O material foi herborizado, identificado e depositado no Herbário da Universidade Estadual de Goiás (HUEG. Das 200 famílias entrevistadas, 75 disseram não fazer uso de plantas com fins medicinais (37,5%, enquanto 125 afirmaram fazê-lo (62,5%. O grupo que utiliza relacionou 35 espécies mais empregadas: hortelã-rasteira (Mentha x villosa L., boldo-sete-dores (Plectranthus barbatus Andrews., capim-cidreira (Cymbopogon citratus (DC. Stapf., quebra-pedra (Phyllanthus niruri L., camomila (Chamomilla recutita (L. Rauschert., poejo (Mentha pulegium L., guaco (Mikania glomerata Spreng., mentrasto (Ageratum conyzoides L., alfavacão (Ocimum gratissimum L., losna (Artemisia canphorata Vill., bálsamo (Eysenhardtia platycarpa Mich., carqueja (Baccharis trimera (Less. DC., funcho (Foeniculum vulgare Mill., babosa (Aloe vera L. e malva (Althaea officinalis L.. Todas as famílias consumidoras (100% afirmaram preferir as plantas cultivadas de forma orgânica, selecionando-as através da boa aparência (68% das famílias e consumindo-as in natura (sem beneficiamento, 100%. A utilização de plantas medicinais em Ipameri é independente do sexo (54%, mulheres e 46%, homens e se estende às várias faixas etárias e também sócio-econômicas, configurando-se assim, um bom mercado consumidor.The aims of this study were: to identify the plant species used for medicinal purposes by the community at Ipameri (Goiás State; to investigate the preferences with respect to the production and marketing

Composição química e atividade in vitro de três óleos essenciais sobre Colletotrichum gloeosporioides do maracujazeiro

Directory of Open Access Journals (Sweden)

C.F. Aquino

2014-01-01

Full Text Available Objetivou-se avaliar a ação de diferentes concentrações de óleos essenciais de três plantas medicinais sobre o crescimento micelial, a produção e a germinação de conídios de Colletotrichum gloeosporioides (Penz.. Utilizou-se os óleos essenciais de Lippia sidoides Cham., Cymbopogon citratus (DC Stapf. e Ocimum gratissimum L. em cinco concentrações (0 µL mL-1, 1 µL mL-1, 3 µL mL-1, 5 µL mL-1 e 7 µL mL-1 com 4 repetições no delineamento inteiramente casualizado, em esquema fatorial 5x3. Os óleos foram analisados por cromatografia gasosa acoplada com espectrometria de massas. Para todas as características verificou-se efeito significativo da interação "Óleo" versus "Concentração". O óleo essencial de C. citratus proporcionou a maior inibição do crescimento micelial em todas as concentrações testadas. Os outros óleos não se diferenciaram, exceto a partir da concentração de 5 µL mL-1, onde o óleo de L. sidoides foi superior ao óleo de O. gratissimum. Na produção e germinação de conídios, o óleo de C. citratus, foi superior aos óleos de L. sidoides e de O. gratissimum nas concentrações de 1 µL mL-1 e 3 µL mL-1, inibindo completamente a produção e germinação a partir da concentração de 3 µL mL-1. As concentrações influenciam em todas as variáveis, ajustando-se à equação do modelo linear. Observa-se o decréscimo nessas, à medida em que se aumentam as concentrações dos óleos testados. Os óleos essenciais testados possuem efeito fungitóxico e fungistático.

In Vitro antifungal activity of essential oils against Colletotrichum gloeosporioides

Science.gov (United States)

Yusoff, Nor Hanis Aifaa; Abdullah, Siti Aisyah; Othman, Zaulia; Zainal, Zamri

2018-04-01

The efficacy of Citrus hystrix, Azadirachta indica and Cymbopogon citratus essential oils were evaluated for controlling the growth of mycelia and spore germination of Colletotrichum gloeosporioides. In order to determine the best essential oil (EO) and suitable concentration of essential oil, in vitro experiment was conducted by preparing a pure culture of antrachnose on Potato Dextrose Agar containing EOs of C. hystrix, A. indica and C. citratus with different concentrations (0.2%, 0.6%, 1% and 1.4% (v/v)). The result shows that C. hystrix essential oil at a concentration of 1.4% (v/v) reduced of mycelia growth of C. gloeosporioides by 29.49%. A second experiment was conducted, but at higher concentration of each essential oils (1.8%, 2.2%, 2.6% and 2.8% (v/v)). Significant difference (p ≤ 0.05) inhibition of mycelia growth was obtained in all treatments except the control. The antifungal index values of essential oils were proportionally increased with concentration of essential oil applied in each treatment. It is concluded that essential oil from C. hystrix are efficient in inhibiting C. gloeosporioides.

Effects of medicinal plant extracts on growth of Leishmania (L. amazonensis and Trypanosoma cruzi Efeito de extratos de plantas medicinais no crescimento de Leishmania (L. amazonensis e Trypanosoma cruzi

Directory of Open Access Journals (Sweden)

Patrícia Shima Luize

2005-03-01

Full Text Available This study describes the screening of extracts obtained from 19 species of plants used in Brazilian traditional medicine for treatment of a variety of diseases. The extracts were tested against axenic amastigote and promastigote forms of Leishmania (L. amazonensis, and epimastigote forms of Trypanosoma cruzi in vitro at a concentration of 100 mg/ml. Baccharis trimera, Cymbopogon citratus, Matricaria chamomilla, Mikania glomerata, Ocimum gratissimum, Piper regnellii, Prunus domestica, Psidium guajava, Sambucus canadensis, Stryphnodendron adstringens, Tanacetum parthenium, and Tanacetum vulgare showed significant effects against one or both parasites, with a percentage of growth inhibition between 49.5 and 99%. The extracts showed no cytotoxic effect on sheep erythrocytes. These medicinal plants may be sources of new compounds that are clinically active against L. amazonensis and T. cruzi.Este estudo descreve a triagem de extratos obtidos de 19 espécies de plantas usadas na medicina tradicional brasileira para o tratamento de várias doenças. Os extratos foram testados contra formas amastigota axênica e promastigota de Leishmania (L. amazonensis, e formas epimastigota de Trypanosoma cruzi in vitro na concentração de 100 mg/ml. Baccharis trimera, Cymbopogon citratus, Matricaria chamomilla, Mikania glomerata, Ocimum gratissimum, Piper regnellii, Prunus domestica, Psidium guajava, Sambucus canadensis, Stryphnodendron adstringens, Tanacetum parthenium, e Tanacetum vulgare apresentaram efeito significante contra um ou ambos parasitas, com a porcentagem de inibição de crescimento entre 49,5 e 99%. Os extratos não mostraram efeito citotóxico em hemácias de carneiro. Essas plantas medicinais podem ser fontes alternativas de novos compostos clinicamente ativos contra L. amazonensis e T. cruzi.

Atividade antiviral de extratos de plantas medicinais disponíveis comercialmente frente aos herpesvírus suíno e bovino Antiviral activity of commercially available medicinal plants on suid and bovine herpesviruses

Directory of Open Access Journals (Sweden)

V.M. Kaziyama

2012-01-01

Full Text Available O presente trabalho teve como objetivo pesquisar a atividade antiviral in vitro de plantas medicinais disponíveis comercialmente sobre herpesvírus suíno (SuHV-1 e bovino (BoHV-1. As espécies adquiridas foram Mikania glomerata, Cymbopogon citratus, Equisetum arvense, Peumus boldus, Solanum paniculatum, Malva sylvestris, Piper umbellatun e Solidago microglossa. A citotoxicidade dos extratos foi avaliada na linhagem celular MDBK pelas alterações morfológicas das células e obtenção da concentração máxima não citotóxica (CMNC de cada planta. A atividade antiviral foi realizada com os extratos em suas respectivas CMNC e avaliada com base na redução do título viral e expressos em porcentagem de inibição. Os extratos aquosos de Peumus boldus e Solanum paniculatum apresentaram atividade antiviral sobre o SuHV-1 com 98% de inibição viral enquanto o de Peumus boldus inibiu apenas o BoHV-1 em 99%.This paper aims to find commercially available medicinal plants showing antiviral activity in vitro on suid and bovine herpesviruses. The following species were tested: Mikania glomerata, Cymbopogon citratus, Equisetum arvense, Peumus boldus, Solanum paniculatum, Malva sylvestris, Piper umbellatun and Solidago microglossa. The cytotoxicity was evaluated by morphological changes in cells determining the maximum not cytotoxic concentration (MNCC. The antiviral activity was evaluated by viral title reduction. The extracts from Peumus boldus and Solanum paniculatum showed antiviral activity against SuHV-1 with 98% of inhibition. The extract of Peumus boldus also showed activity against BoHV-1 with 99% of inhibition.

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%)

Antimicrobial Susceptibility of Escherichia coli Strains Isolated from Alouatta spp. Feces to Essential Oils

Directory of Open Access Journals (Sweden)

Valéria Maria Lara

2016-01-01

Full Text Available This study evaluated the in vitro antibacterial activity of essential oils from Lippia graveolens (Mexican oregano, Origanum vulgaris (oregano, Thymus vulgaris (thyme, Rosmarinus officinalis (rosemary, Cymbopogon nardus (citronella, Cymbopogon citratus (lemongrass, and Eucalyptus citriodora (eucalyptus against Escherichia coli (n=22 strains isolated from Alouatta spp. feces. Minimum inhibitory concentration (MIC and minimum bactericidal concentration (MBC were determined for each isolate using the broth microdilution technique. Essential oils of Mexican oregano (MIC mean = 1818 μg mL−1; MBC mean = 2618 μg mL−1, thyme (MIC mean = 2618 μg mL−1; MBC mean = 2909 μg mL−1, and oregano (MIC mean = 3418 μg mL−1; MBC mean = 4800 μg mL−1 showed the best antibacterial activity, while essential oils of eucalyptus, rosemary, citronella, and lemongrass displayed no antibacterial activity at concentrations greater than or equal to 6400 μg mL−1. Our results confirm the antimicrobial potential of some essential oils, which deserve further research.

Antimicrobial Susceptibility of Escherichia coli Strains Isolated from Alouatta spp. Feces to Essential Oils

Science.gov (United States)

Carregaro, Adriano Bonfim; Santurio, Deise Flores; de Sá, Mariangela Facco; Santurio, Janio Moraes; Alves, Sydney Hartz

2016-01-01

This study evaluated the in vitro antibacterial activity of essential oils from Lippia graveolens (Mexican oregano), Origanum vulgaris (oregano), Thymus vulgaris (thyme), Rosmarinus officinalis (rosemary), Cymbopogon nardus (citronella), Cymbopogon citratus (lemongrass), and Eucalyptus citriodora (eucalyptus) against Escherichia coli (n = 22) strains isolated from Alouatta spp. feces. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for each isolate using the broth microdilution technique. Essential oils of Mexican oregano (MIC mean = 1818 μg mL−1; MBC mean = 2618 μg mL−1), thyme (MIC mean = 2618 μg mL−1; MBC mean = 2909 μg mL−1), and oregano (MIC mean = 3418 μg mL−1; MBC mean = 4800 μg mL−1) showed the best antibacterial activity, while essential oils of eucalyptus, rosemary, citronella, and lemongrass displayed no antibacterial activity at concentrations greater than or equal to 6400 μg mL−1. Our results confirm the antimicrobial potential of some essential oils, which deserve further research. PMID:27313638

Óleos essenciais no controle pós-colheita de Colletotrichum gloeosporioides em mamão Essential oils on postharvest control of Colletotrichum gloeosporioides in papaya fruit

Directory of Open Access Journals (Sweden)

P.R. Carnelossi

2009-01-01

Full Text Available Os subprodutos de plantas medicinais têm sido estudados como uma alternativa para o controle de doenças de plantas visando amenizar e/ou reduzir o uso abusivo de agrotóxicos, principalmente em condições pós-colheita. Assim, este trabalho teve como objetivo avaliar, in vitro e in vivo, o controle de Colletotrichum gloeosporioides, agente causal da antracnose do mamão em pós-colheita, por óleos essenciais (OEs de Cymbopogon citratus, Eucalyptus citriodora, Mentha arvensis e Artemisia dracunculus. Para inibição do crescimento micelial in vitro, os OEs foram incorporados ao BDA (Batata-dextrose-ágar tendo-se observado a inibição total ou parcial do crescimento micelial e da esporulação deste fitopatógeno, dependendo do óleo essencial utilizado. No ensaio in vivo utilizaram-se os OEs de C. citratus (1% e E. citriodora (1%. A inoculação com o fitopatógeno foi concomitante e 24 h após os tratamentos alternativos, que foram: óleos essenciais de C. citratus e de E. citriodora (1% e biomassa cítrica (150 mL 100 L-1 (Ecolife®. Os parâmetros avaliados foram severidade da doença, redução da massa, diâmetro, comprimento final dos frutos, pH e a concentração de sólidos solúveis totais (ºBrix. Pode-se observar que, no controle da doença, os frutos tratados e imediatamente inoculados com o fitopatógenos apresentaram maior AACPD (Área Abaixo da Curva do Progresso da Doença. Porém, frutos tratados e inoculados 24 h após os tratamentos apresentaram maior controle da doença, confirmando o potencial dos óleos essenciais testados no presente trabalho.The products from medicinal plants have been studied as an alternative in the control of plant diseases in order to mitigate and / or reduce pesticide abuse mainly in postharvest. Thus, the present study aimed to evaluate, in vitro and in vivo, the control of Colletotrichum gloeosporioides, the causative agent of papaya anthracnose, in postharvest using essential oils (EOs of

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.

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.

Control of Ralstonia Solanacearum The Causal Agent of Brown Rot in Potato Using Essential Oils

International Nuclear Information System (INIS)

Salem, E.A.

2011-01-01

Five essential oils, namely peppermint (Mentha piperita L.), caraway (Carium carvum L.), fennel (Foeniculum vulgare Mill.), lemongrass (Cymbopogon citratus Staph.) and thyme (Thymus vulgaris), were used separately against Ralstonia solanacearum; the causal agent of brown rot in potato. The most two effective oils (peppermint and thyme) were used in vitro and in vivo after testing their effects on potato tubers buds germination. Peppermint inhibited buds germination but thyme have no effects on buds germination. In vivo, the control of brown rot using thyme oil in glass house experiment reduced the percentage of brown rot infection to 30.6% and reduced the severity of disease from 5 to 3.

A comparative study of leaves extracts for corrosion inhibition effect on aluminium alloy in alkaline medium

Directory of Open Access Journals (Sweden)

Namrata Chaubey

2017-12-01

Full Text Available This paper deals with the comparative inhibition study of some plants leaves extract namely Cannabis sativa (CS, Rauwolfia serpentina (RS, Cymbopogon citratus (CC, Annona squamosa (AS and Adhatoda vasica (AV on the corrosion of aluminium alloy (AA in 1 M NaOH. The corrosion tests were performance by using gravimetric, electrochemical impedance spectroscopy (EIS, potentiodynamic polarization and linear polarization resistance (LPR techniques. RS showed maximum inhibition efficiency (η%, 97% at 0.2 g L−1. Potentiodynamic polarization curves justified that all the inhibitors are mixed-type. Surface morphology of AA is carried by scanning electron microscopy (SEM and atomic force microscopy (AFM.

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

Evaluación in vitro de la actividad anti Trypanosoma cruzi de aceites esenciales de diez plantas medicinales

Directory of Open Access Journals (Sweden)

Juan Rojas

2010-07-01

Full Text Available Objetivos: Determinar la actividad anti Trypanosoma cruzi in vitro de los aceites esenciales de 10 plantas medicinales. Además, determinar la actividad citotóxica de los aceites contra células de mamíferos y la actividad modulatoria de los aceites sobre el óxido nítrico. Diseño: Estudio experimental in vitro. Institución: Instituto de Investigaciones Clínicas e Instituto de Medicina Tropical, Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Perú. Material biológico: Epimastigotes de Trypanosoma cruzi, células Raw 264.7, aceites esenciales de Mentha X piperita L (menta, Rosmarinus officinalis L (romero, Chenopodium ambrosioides L (paico, Eucaliptus globulus Labill (eucalipto, Artemisia absinthium L (ajenjo, Melissa officinalis L (toronjil, Minthostachys setosa Brig (muña, Cimbopogon citratus (hierba luisa, Aloysia triphylla (cedrón y Mentha spicata L (hierba buena. Método: La actividad tripanocida se evaluó contra epimastigotes cultivados en medio LIT, incubados por 48 horas a 37ºC en incubador humidificado con CO2 al 5%. El cristal violeta se utilizó como control positivo. La actividad citotóxica de los productos contra células mamíferas se evaluó en células RAW 264.7 y la actividad modulatoria de los compuestos sobre óxido nítrico también se determinó en los cultivos de células RAW 264.7. Principales medidas de resultados: Porcentaje de inhibición de viabilidad y CI50. Resultados: Los aceites esenciales de Cymbopogon citratus (hierba luisa y Aloysia triphylla (cedrón inhibieron significativamente el crecimiento de la forma epimastigote de T. cruzi, con una CI50 de 63,09 y 96,49 μg/mL, respectivamente. No hubo variaciσn significativa de la concentraciσn de óxido nítrico y tampoco se evidenció citotoxicidad. Conclusiones: Los aceites esenciales de Cymbopogon citratus y Aloysia triphylla mostraron actividad anti-Trypanosoma cruzi in vitro y no fueron citotóxicas para las células mamíferas.

Ação antioxidante de chás e condimentos de grande consumo no Brasil

Directory of Open Access Journals (Sweden)

Selene M. de Morais

Full Text Available Antioxidantes são compostos que atuam inibindo e/ou diminuindo os efeitos desencadeados pelos radicais livres e compostos oxidantes. Os chás são bebidas populares e fontes significativas de compostos fenólicos, sendo considerados importantes integrantes das dietas devido às suas propriedades antioxidantes. O presente trabalho teve como objetivo avaliar a ação antioxidante de uma variedade de chás e condimentos mais consumidos no Brasil. Os chás analisados foram das plantas: Pneumus boldus Mold., Matricaria recutita L., Cymbopogon citratus (DC Stapf, Baccharis trimera (Less. DC, Camelia sinensis (L O. Kuntze (fermentado, Camelia sinensis (não-fermentado, Lippia alba N.E. Brown,Mentha arvensis L., e Pyrus malus L. Os condimentos analisados foram: Eugenia aromatica Baill, Cinnamonum zeylanicum Blume, Laurus nobilis L. e Origanum vulgare L. O método utilizado para avaliar a ação antioxidante foi o da atividade seqüestradora de radicais livres DPPH em solução metanólica. Todas as amostras analisadas demonstraram atividade em suas diferentes concentrações. Camelia sinensis (não-fermentada foi a mais ativa com CI50= 0,14 mg/mL, cujos principais compostos antioxidantes são epigalocatequinas. Os condimentos mais ativos foram Cinnamonum zeylanicum (CI50 = 0,37 mg/mL, Eugenia aromatica Baill (CI50 = 0,46 mg/mL e Laurus nobilis (CI50 = 0,76 mg/mL, cujo principal antioxidante relatado foi o eugenol.

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.

Directory of Open Access Journals (Sweden)

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.

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.

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 ...

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.

Effect of lemongrass tea consumption on estimated glomerular filtration rate and creatinine clearance rate.

Science.gov (United States)

Ekpenyong, Christopher E; Daniel, Nyebuk E; Antai, Atim B

2015-01-01

The existing research findings regarding the effects of lemongrass (Cymbopogon citratus) tea on renal function indices are conflicting and inconclusive. In the present study, we investigated the effects of infusions prepared from C citratus leaves on creatinine clearance rate (CCr) and estimated glomerular filtration rate (eGFR) in humans. One hundred 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 days. Serum and urinary levels of urea, creatinine, pH, specific gravity, uric acid, electrolytes, diuretic indices, and eGFR were assessed at days 0, 10, and 30 after the initiation of treatment. Results obtained on days10 and 30 were compared with baseline values. CCr and eGFR decreased significantly at day 30 in both male and female subjects in all the groups and in females treated with infusion prepared from 8 g of C citratus leaf powder for 10 days. At day 10, CCr and eGFR were unchanged in those treated with infusions prepared from 2 or 4 g of the leaf powder, whereas diuretic indices (urine volume, urination frequency, diuretic action, and saliuretic indices) increased above the baseline levels. Serum and urinary creatinine levels significantly increased (P < .05) in both male and female subjects in all the groups. Serum urea significantly increased in the groups treated with infusions prepared from 4 or 8 g of the leaf powder (P < .05) for 30 days. Serum electrolytes remained unchanged, but their urinary levels increased. We observed dose- and time-dependent adverse effects of C citratus on CCr and eGFR. At a high dose or with prolonged treatment with a low dose, eGFR decrease may be followed by a decline in the other renal function indices. Copyright © 2015 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

Insecticidal Activity of Some Traditionally Used Ethiopian Medicinal Plants against Sheep Ked Melophagus ovinus

Directory of Open Access Journals (Sweden)

Negero Gemeda

2014-01-01

Full Text Available Twelve medicinal plants and a commercially used drug Ivermectin were examined for insecticidal activity against Melophagus ovinus sheep ked at different time intervals using in vitro adult immersion test. The findings show that at 3.13 µL/mL, 6.25 µL/mL and 12.5 µL/mL concentration of Cymbopogon citratus, Foeniculum vulgare and Eucalyptus globulus essential oils respectively, recorded 100% mortalities against M. ovinus within 3 hour of exposure. Significantly higher insecticidal activity of essential oils was recorded (P=0.00 when compared to 10 μg/mL Ivermectin after 3-hour exposure of M. ovinus at a concentration of ≥1.57 μL/mL, ≥3 μL/mL, and ≥12.7 μL/mL essential oils of C. citratus, F. vulgare, and E. globulus, respectively. Among essential oils, C. citratus has showed superior potency at a three-hour exposure of the parasite (P=0.00 at a concentration of ≥0.78 μL/mL. Strong antiparasitic activity was recorded by aqueous extract of Calpurnia aurea (80% mortality at a concentration of 200 mg/mL within 24 h among aqueous extracts of 9 medicinal plants. The results indicated all the four medicinal plants, particularly those tested essential oils, can be considered as potential candidates for biocontrol of M. ovinus sheep ked.

Insecticidal Activity of Some Traditionally Used Ethiopian Medicinal Plants against Sheep Ked Melophagus ovinus.

Science.gov (United States)

Gemeda, Negero; Mokonnen, Walelegn; Lemma, Hirut; Tadele, Ashenif; Urga, Kelbessa; Addis, Getachew; Debella, Asfaw; Getachew, Mesaye; Teka, Frehiwot; Yirsaw, Kidist; Mudie, Kissi; Gebre, Solomon

2014-01-01

Twelve medicinal plants and a commercially used drug Ivermectin were examined for insecticidal activity against Melophagus ovinus sheep ked at different time intervals using in vitro adult immersion test. The findings show that at 3.13 µL/mL, 6.25 µL/mL and 12.5 µL/mL concentration of Cymbopogon citratus, Foeniculum vulgare and Eucalyptus globulus essential oils respectively, recorded 100% mortalities against M. ovinus within 3 hour of exposure. Significantly higher insecticidal activity of essential oils was recorded (P = 0.00) when compared to 10  μ g/mL Ivermectin after 3-hour exposure of M. ovinus at a concentration of ≥1.57  μ L/mL, ≥3  μ L/mL, and ≥12.7  μ L/mL essential oils of C. citratus, F. vulgare, and E. globulus, respectively. Among essential oils, C. citratus has showed superior potency at a three-hour exposure of the parasite (P = 0.00) at a concentration of ≥0.78  μ L/mL. Strong antiparasitic activity was recorded by aqueous extract of Calpurnia aurea (80% mortality) at a concentration of 200 mg/mL within 24 h among aqueous extracts of 9 medicinal plants. The results indicated all the four medicinal plants, particularly those tested essential oils, can be considered as potential candidates for biocontrol of M. ovinus sheep ked.

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

Screening for larvicidal activity of ethanolic and aqueous extracts of selected plants against Aedes aegypti and Aedes albopictus larvae

Directory of Open Access Journals (Sweden)

Michael Russelle Alvarez

2016-02-01

Full Text Available Objective: To screen for larvicidal activity of aqueous and ethanolic extracts (95% ethanol from Selaginella elmeri, Christella dentata, Elatostema sinnatum, Curculigo capitulata, Euphorbia hirta, Murraya koenigii (M. koenigii, Alpinia speciosa, Cymbopogon citratus, Eucalyptus globulus (E. globulus, Jatropha curcas (J. curcas, Psidium guajava, Gliricidia sepium, Ixora coccinea and Capsicum frutescens (C. frutescens against Aedes aegypti (A. aegypti and Aedes albopictus (A. albopictus 3rd instar larvae. Methods: Ethanolic and aqueous extracts were screened for larvicidal activity by exposing the A. aegypti and A. albopictus 3rd instar larvae (15 larvae per trial, triplicates for 48 h, counting the mortalities every 24 h. Additionally, phytochemical screening for flavonoids, tannins, alkaloids, anthraquinones, anthrones, coumarins, indoles and steroids were performed on active extracts using spray tests. Results: Against A. aegypti, the three most active extracts were C. frutescens ethanolic (100% after 24 and 48 h, J. curcas ethanolic (84.44% after 24 h and 88.89% after 48 h and M. koenigii ethanolic (53.33% after 24 h and 71.11% after 48 h. On the other hand, against A. albopictus, the three most active extracts were C. frutescens ethanolic (93.33% after 24 h and 100% after 48 h, J. curcas ethanolic (77.78% after 24 h and 82.22% after 48 h and E. globulus ethanolic (64.44% after 24 h and 73.33% after 48 h. Phytochemical screening was also performed on the active extracts, revealing alkaloids, tannins, indoles and steroids. Conclusios: The results demonstrate the larvicidal activities of ethanolic extracts of Cymbopogon citratus, Euphorbia hirta, Ixora coccinea, Gliricidia sepium, M. koenigii, E. globulus, J. curcas and C. frutescens against A. aegypti and A. albopictus 3rd instar larvae. These could be used as potential larvicidal agents for the control of these mosquitoes.

Antifungal Effect of Plant Essential Oils on Controlling Phytophthora Species

Directory of Open Access Journals (Sweden)

Jahanshir Amini

2016-02-01

Full Text Available In this study, antifungal activity of essential oils of Cymbopogon citratus and Ocimum basilicum and two fungicides Mancozeb and Metalaxyl-Mancozeb in six different concentrations were investigated for controlling three species of Phytophthora, including P. capsici, P. drechsleri and P. melonis on pepper, cucumber and melon under in vitro and greenhouse conditions, respectively. Under the in vitro condition, the median effective concen- tration (EC₅₀ values (ppm of plant essential oils and fungicides were measured. In greenhouse, soil infested with Phytophthora species was treated by adding 50 ml of essential oils and fungicides (100 ppm. Disease severity was determined after 28 days. Among two tested plant essential oils, C. citratus had the lowest EC₅₀ values for inhibition of the mycelial growth of P. capsici (31.473, P. melonis (33.097 and P. drechsleri (69.112, respectively. The mean EC₅₀ values for Metalaxyl-Mancozeb on these pathogens were 20.87, 20.06 and 17.70, respectively. Chemical analysis of plant essential oils by GC-MS showed that, among 42 compounds identified from C. citratus, two compounds β-geranial (α-citral (39.16% and z-citral (30.95% were the most abundant. Under the greenhouse condition, Metalaxyl-Mancozeb caused the greatest reduction in disease severity, 84.2%, 86.8% and 92.1% on melon, cucumber, and pepper, respectively. The C. citratus essential oil reduced disease severity from 47.4% to 60.5% compared to the untreated control (p≤0.05. Essential oils of O. basilicum had the lowest effects on the pathogens under in vitro and greenhouse conditions. These results show that essential oils may contribute to the development of new antifungal agents to protect the crops from Phytophthora diseases.

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

Science.gov (United States)

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.

Antibiotic Properties of the endophytic Streptomyces Spp. Isolated from the Leaves of Myanmar Medicinal Plants

International Nuclear Information System (INIS)

Aye Pe; Mar Mar Nyein; Win Maung

2002-02-01

Three medicinal plants of Myanmar are selected in the study of endophytic microorganisms and are taxonomically classified and identified to be Sa-ba-lin (Cymbopogon citratus Stapf.), Shazaungtinga- neah (Euphorbia splendens Bojer. ex Hooker) and Ma-shaw (Sauropus grandifolius Pax. and Hoffm.). The screening of endophytic microorganisms is performed according to the ISP method (International Streptomyces Projects 1993). The morphological and physicochemical properties of isolated strains are studied and identified to be the Genus Streptomyces. The test of apparent antimicrobial activity of isolated Streptomyces is done on 18 strains of pathogenic bacteria. It is found that the isolated endophytic Sireptomyces showed the significant antibacterial activity on most of the test organisms. (author)

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...

Toxicity and repellency of essential oils to Zabrotes subfasciatus (Boheman (Coleoptera, Chrysomelidae, Bruchinae in Phaseolus vulgaris L Toxicidade e repelência de óleos essenciais a Zabrotes subfasciatus (Boheman (Coleoptera, Chrysomelidae, Bruchinae em grãos de Phaseolus vulgaris L

Directory of Open Access Journals (Sweden)

Solange Maria de França

2012-09-01

Full Text Available The effects of tangerine (Phaseolus vulgaris Blanco, lemon (Citrus medica limonum Lush, pear orange (Citrus sinensis L. Osbeck, red copaiba (Copaifera langsdorffii Desf., rosemary (Baccharis dracunculifolia De Candole, Eucalyptus (Eucalyptus globulus Labillardière and E. citriodora Hook, lemongrass (Cymbopogon citratus Stapf. and citronella (Cimbopogon nardus Linnaeus oils at several concentrations on Zabrotes subfasciatus (Boheman were studied. In toxicity tests, grains of Phaseolus vulgaris L. cv. Rajadinho were impregnated with oils and infested with adults of Z. subfasciatus up to 24 hours old. All tested oils were effective in reducing the viable egg-laying and adult emergence of this pest, in function of the concentrations used, highlighting E. citriodora and E. globulus oils which caused 100% effectiveness from 0.5 mL Kg-1 concentration. In repellency tests, two arenas consisting of plastic containers, connected symmetrically to a central box by two plastic tubes were used. In one of the boxes, untreated beans were placed and on the other ones beans treated with each oil concentration were used. In the central box, five couples of Z. subfasciatus were released. Grains of P. vulgaris treated with oils of E. citriodora, C. citratus and C. oleifera reduced the attraction percentage of Z. subfasciatus adults, while the E. globulus increased this percentage. The percentages of reduced viable eggs ranged from 17.9% (C. medica limonum to 93.3% (C. nardus, while the reduction on the number of emerged insects was 23.9% and 95.9%, respectively for these same oils.Estudaram-se os efeitos dos óleos de tangerina 'Cravo' (Phaseolus vulgaris Blanco, limão-siciliano (Citrus medica limonum Lush, laranja 'Pêra' (Citrus sinensis L. Osbeek, copaíba-vermelha (Copaifera langsdorffii Desf., alecrim-do-campo (Baccharis dracunculifolia De Candole, eucalipto (Eucalyptus globulus Labillardière e Eucalyptus citriodora Hook, capim-santo (Cymbopogon citratus

Atividade antimicrobiana de óleos essenciais em bactérias patogênicas de origem alimentar Antimicrobial activity of essential oils against sessile and planktonic pathogens of food source

Directory of Open Access Journals (Sweden)

C. Valeriano

2012-01-01

Full Text Available Objetivou-se identificar e quantificar os constituintes e avaliar a atividade antimicrobiana dos óleos essenciais de Mentha piperita, Cymbopogon citratus, Ocimum basilicum e Origanum majorana contra cepas de Escherichia coli enteropatogênica, Salmonella enterica Enteritidis, Listeria monocytogenes e Enterobacter sakazaki. A obtenção dos óleos essenciais foi realizada a partir de folhas secas, empregando-se a técnica de hidrodestilação e utilizando-se a aparelho de Clevenger modificado. A atividade antibacteriana dos óleos essenciais foi determinada pelo método de difusão em ágar. Observou-se que os óleos essenciais inibiram o crescimento bacteriano, mas a efetividade foi variada. Entre os óleos essenciais testados, M. piperita apresentou maior atividade antibacteriana para E. coli, (8.106 UA mL-1 quando comparada as demais bactérias, atividade moderada para Salmonella enterica Enteritidis e Enterobacter sakazakii (1.706 e 3.200 UA mL-1 respectivamente e baixa atividade para Listeria monocytogenes (106,67 UA mL-1. Já óleo essencial de Cymbopogon citratus apresentou maior atividade antimicrobiana frente a E. coli (9.386 UA mL-1 e atividade moderada frente a Enterobacter sakazakii, Salmonella enterica Enteritidis e Listeria monocytogenes (2.773 UA mL-1 para ambas. Ocimum basilicum apresentou maior atividade antibacteriana frente E. coli e Enterobacter sakazakii (6.826 e 8.106 UA mL-1 respectivamente, moderada atividade frente a Salmonella enterica Enteritidis (1.600 UA mL-1 e não apresentou atividade frente a Listeria monocytogenes.Origanum majorana também foi testado neste estudo e apresentou maior atividade antimicrobiana frente E. coli (5.973 UA mL-1, atividade moderada para Salmonella enterica Enteritidis e Enterobacter sakazakii (1.706 e 2.346 UA mL-1 , respectivamente e não apresentou atividade para Listeria monocytogenes.ABSTRACT The objective of this work was to identify and quantify the constituents, and to evaluate the

Endophytic l-asparaginase-producing fungi from plants associated with anticancer properties

Directory of Open Access Journals (Sweden)

YiingYng Chow

2015-11-01

Full Text Available Endophytes are novel sources of natural bioactive compounds. This study seeks endophytes that produce the anticancer enzyme l-asparaginase, to harness their potential for mass production. Four plants with anticancer properties; Cymbopogon citratus, Murraya koenigii, Oldenlandia diffusa and Pereskia bleo, were selected as host plants. l-Asparaginase-producing endophytes were detected by the formation of pink zones on agar, a result of hydrolyzes of asparagine into aspartic acid and ammonia that converts the phenol red dye indicator from yellow (acidic condition to pink (alkaline condition. The anticancer enzyme asparaginase was further quantified via Nesslerization. Results revealed that a total of 89 morphotypes were isolated; mostly from P. bleo (40, followed by O. diffusa (25, C. citratus (14 and M. koenigii (10. Only 25 of these morphotypes produced l-asparaginase, mostly from P. bleo and their asparaginase activities were between 0.0069 and 0.025 μM mL−1 min−1. l-Asparaginase producing isolates were identified as probable species of the genus Colletotrichum, Fusarium, Phoma and Penicillium. Studies here revealed that endophytes are good alternative sources for l-asparaginase production and they can be sourced from anticancer plants, particularly P. bleo.

Ação e caracterização química de óleos essenciais no manejo da antracnose do maracujá Chemical characterization and action of essential oils in the management of anthracnose on passion fruits

Directory of Open Access Journals (Sweden)

César Fernandes Aquino

2012-12-01

Full Text Available Objetivou-se avaliar dois métodos de inoculação de Colletotrichum gloeosporioides em maracujá, testar a patogenicidade de diferentes isolados, o efeito fungitóxico e a composição química dos óleos essenciais das espécies medicinais alecrim-pimenta (Lippia sidoides Cham., capim-santo [Cymbopogon citratus (D. C. Stapf.], alfavaca-cravo (Ocimum gratissimum L., no controle da antracnose [Colletotrichum gloeosporioides (Penz.], associado ao estádio de maturação de frutos de maracujazeiro-amarelo. Avaliaram-se três experimentos, onde se testou a patogenicidade de seis isolados do fungo em delineamento inteiramente casualizado, com seis repetições, outro com o mesmo delineamento em esquema fatorial 2x2 (suspensão de conídios e disco de micélio e frutos (verdes e maduros, com seis repetições. No tratamento com frutos, utilizou-se o delineamento inteiramente casualizado, em esquema fatorial 5x3+1, sendo cinco concentrações (0; 2; 4; 6 e 8µL mL-1 e três espécies medicinais, mais o tebuconazol, com cinco repetições. Fez-se a caracterização química dos óleos por cromatografia gasosa, com espectrometria de massas. Todos os isolados foram patogênicos. Os frutos maduros apresentaram maior diâmetro das lesões, quando inoculados com suspensão de conídios. O óleo de C. citratus proporcionou o menor diâmetro das lesões nos frutos, até a concentração de 6 µL mL-1. Na concentração de 8 µL mL-1, todos os óleos inibiram o desenvolvimento do fungo. O timol (30,24%, o citral (77,74% e o eugenol (92,89% foram componentes majoritários em L. sidoides, C. citratus e O. gratissimum, respectivamente.The objective was to evaluate two methods of inoculation of Colletotrichum gloeosporioides on passion fruit, test the pathogenicity of different isolates, fungitoxic effect and the chemical composition of the essential oils from medicinal plants Lippia sidoides (Cham., Cymbopogon citratus (D. C. Stapf. and Ocimum gratissimum (L., in

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.

A reversed-phase compatible thin-layer chromatography autography for the detection of acetylcholinesterase inhibitors.

Science.gov (United States)

Ramallo, I Ayelen; García, Paula; Furlan, Ricardo L E

2015-11-01

A dual readout autographic assay to detect acetylcholinesterase inhibitors present in complex matrices adsorbed on reversed-phase or normal-phase thin-layer chromatography plates is described. Enzyme gel entrapment with an amphiphilic copolymer was used for assay development. The effects of substrate and enzyme concentrations, pH, incubation time, and incubation temperature on the sensitivity and the detection limit of the assay were evaluated. Experimental design and response surface methodology were used to optimize conditions with a minimum number of experiments. The assay allowed the detection of 0.01% w/w of physostigmine in both a spiked Sonchus oleraceus L. extract chromatographed on normal phase and a spiked Pimenta racemosa (Mill.) J.W. Moore leaf essential oil chromatographed on reversed phase. Finally, the reversed-phase thin-layer chromatography assay was applied to reveal the presence of an inhibitor in the Cymbopogon citratus (DC.) Stapf essential oil. The developed assay is able to detect acetylcholinesterase inhibitors present in complex matrixes that were chromatographed in normal phase or reversed-phase thin-layer chromatography. The detection limit for physostigmine on both normal and reversed phase was of 1×10(-4) μg. The results can be read by a change in color and/or a change in fluorescence. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Acúmulo e efeitos fitotóxicos do flúor em folhas de boldo-gambá e capim-cidreira utilizadas para chás Fluorine accumulation and its phytotoxic effects in blue coleus and lemongrass leaves used for tea

Directory of Open Access Journals (Sweden)

Naiara Viana Campos

2010-07-01

Full Text Available O objetivo deste trabalho foi avaliar o potencial de acúmulo de fluoreto em folhas de boldo-gambá (Plectranthus neochilus e capim-cidreira (Cymbopogon citratus, determinar o percentual de liberação do poluente por meio da infusão e caracterizar, visual e microscopicamente, os danos foliares causados pelo poluente. Mudas das duas espécies foram submetidas a nevoeiro simulado com fluoreto de potássio. O acúmulo de fluoreto na matéria seca foi mensurado com eletrodo específico em folhas lavadas e não lavadas, infundidas e não infundidas. O percentual de flúor disponibilizado nos chás foi superior para capim-cidreira, embora essa espécie apresente acúmulo de flúor menor que o boldo-gambá. Não foram observados sintomas visuais nas folhas das espécies estudadas, mas ao microscópio eletrônico de varredura, constatou-se a alteração da turgidez das células epidérmicas, ruptura da cutícula e deformação de estômatos e tricomas. O elevado teor de fluoreto nas folhas de C. citratus e P. neochilus e a ausência de sintomas visuais evidenciam que as espécies são tolerantes ao poluente. A lavagem das folhas em água é ineficiente para a remoção do flúor. O acúmulo e a liberação diferenciais de flúor estão relacionados às características morfoanatômicas das espécies analisadas.The objective of this work was to evaluate the fluoride accumulation in leaves of blue coleus (Plectranthus neochilus and lemongrass (Cymbopogon citratus, the percentage of fluoride released through infusion and to characterize visually and through microscopy the injuries caused by the pollutant. Saplings of the species were subjected to a simulated fog with potassium fluoride. Fluoride accumulation in dry matter was measured by a specific electrode in washed and unwashed leaves, subjected and not subjected to infusion. The percentage of available fluorine in teas was higher for lemongrass leaves, even though this species shows a lower fluorine

Fungos endofíticos associados a plantas medicinais Endophytic fungi associated with medicinal plants

Directory of Open Access Journals (Sweden)

V Mussi-Dias

2012-01-01

Full Text Available Com a utilização de plantas medicinais em infusões, xaropes, tinturas, ungüentos, dentre outras formas, pressupõe-se que fungos endofíticos, presentes no interior das plantas, mas sem causar doença, possam tornar-se um componente destes produtos, principalmente quando utilizados in natura. Além disso, os fungos endofíticos podem também produzir substâncias tóxicas aos usuários ou mesmo alterar o metabolismo vegetal, modificando a composição e as propriedades medicinais, assim como, a qualidade do produto armazenado e comercializado. Neste sentido, objetivou-se isolar e identificar a flora fúngica endofítica de onze espécies medicinais escolhidas ao acaso. Obtiveram-se culturas-puras dos fungos Phomopsis, Colletotrichum, Pestalotia, Trichoderma, Fusarium, Nigrospora e Glomerella ocorrendo endofiticamente em Plectranthus barbatus, Vernonia condensata, Pfaffia paniculata, Foeniculum vulgare, Cymbopogon citratus, Cymbopogon nardus, Cordia curassavica, Maytenus ilicifolia, Punica granatum, Morus nigra e Bauhinia forficata. As espécies vegetais em que se identificaram o maior número de fungos endofíticos foram Vernonia condensata, Punica granatum e Morus nigra. Todos os fungos recuperados neste trabalho apresentaram características estritamente endofíticas, não manifestando patogenicidade nas espécies hospedeiras. Dentre os fungos detectados, especial atenção deve ser dada ao gênero Fusarium, uma vez que inúmeras espécies deste gênero são conhecidas produtoras de micotoxinas e constituem-se em importantes patógenos pós-colheita.With the use of medicinal plants in infusions, syrups, dyes, unguents, among other forms, it is expected that endophytic fungi, present inside the plants but not causing diseases, become components of these products, especially when used in natura. In addition, endophytic fungi can produce toxic substances to the users or even modify the plant metabolism, altering the medicinal composition and

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...

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.

INDUCING RESISTANCE IN COTTON AGAINST COLLETOTRICHUM GOSSYPII VAR. CEPHALOSPORIOIDES WITH ESSENTIAL OILS

Directory of Open Access Journals (Sweden)

B. T. Santos

2016-11-01

Full Text Available This study aimed to evaluate the potential of essential oils of rosemary (Rosmarinus officinalis, baccharis (Baccharis trimera, lemon grass (Cymbopogon citratus, basil (Ocimum basilicum and eucalyptus (Corymbia citriodora in inducing resistance in cotton plants against C. gossypii var. cephalosporioides. The inductive effect of the essential oils was evaluated in plants growing in pots in the environment, which were treated with 1% essential oil at 47 days of age. 24 hours after elicitor treatment the plants were inoculated with a suspension of 1.5 x 105 conidia mL-1 of C. gossypii var. cephalosporioides. Five evaluations were performed disease and calculated the area under the disease progress curve. All essential oils showed potential for inducing resistance against cotton C. gossypii var. cephalosporioides.

Green Michael addition of thiols to electron deficient alkenes using KF/alumina and recyclable solvent or solvent-free conditions

Energy Technology Data Exchange (ETDEWEB)

Lenardao, Eder J.; Trecha, Danusia O.; Ferreira, Patricia da C.; Jacob, Raquel G.; Perin, Gelson [Universidade Federal de Pelotas (UFPEL), Pelotas, RS (Brazil). Inst. de Quimica e Geociencias. Lab. de Sintese Organica Limpa (LASOL)]. E-mail: lenardao@ufpel.edu.br

2009-07-01

A general, clean and easy method for the conjugated addition of thiols to citral promoted by KF/Al{sub 2}O{sub 3} under solvent-free or using glycerin as recyclable solvent at room temperature is described. It was found that the solvent-free protocol is applicable to the direct reaction of thiophenol with the essential oil of lemon grass (Cymbopogon citratus) to afford directly 3,7-dimethyl-3-(phenylthio)oct-6-enal, a potential bactericide agent. The method was extended to other electron-poor alkenes with excellent results. For the solvent-free protocol, the use of microwave irradiation facilitated the procedure and accelerates the reaction. The catalytic system and glycerin can be reused up to three times without previous treatment with comparable activity. (author)

Estudo prospectivo da cadeia produtiva do capim-limão: estado do Paraná

Directory of Open Access Journals (Sweden)

Eliane Carneiro Gomes

2004-12-01

Full Text Available A aplicação de prospectiva para cadeias produtivas engloba várias etapas como a segmentação de cada elo, a análise do ambiente institucional e organizacional que envolve a cadeia, a identificação das necessidades e aspirações de cada segmento da cadeia e dos fatores críticos para a melhoria do desempenho. Desta forma, considerando a importância econômica da produção, industrialização e comercialização do capim-limão, Cymbopogon citratus (D.C. Stapf, e visando uma ação integrada do setor agrícola envolvido, este trabalho propõe o estudo prospectivo da cadeia produtiva desta espécie no estado do Paraná, identificando também fatores e condicionantes de qualidade em cada segmento desta cadeia. Para isto, o presente estudo apresenta o panorama da produção agroindustrial e da comunidade produtora agrícola paranaense de capim-limão; identifica e caracteriza os outros segmentos que integram a respectiva cadeia produtiva no Paraná e, por fim, identifica e analisa os principais gargalos, elos faltantes e pontos de estrangulamento. Evidenciaram-se como principais componentes da cadeia produtiva: a unidade produtiva, a agroindústria, a indústria (alimentícia, farmacêutica e química e o mercado consumidor interno (atacadista e varejista e externo. Com esse estudo prospectivo, espera-se contribuir para a implementação de medidas político-organizacionais, entre os agentes econômicos dos setores público e privado, que fazem parte da cadeia produtiva do capim-limão, possibilitando-lhes desenvolver estratégias que aumentem a competitividade e conduzam à expansão do mercado.The application of a prospective study to productive chains incorporates several stages like the segmentation of each link, the analysis of institutional and organizational environments to include the chain, the identification of necessities and aspirations of each chain segment and the critical factors for the improvement of performance. Thus

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....

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...

Empirical modeling of drying kinetics and microwave assisted extraction of bioactive compounds from Adathoda vasica

Directory of Open Access Journals (Sweden)

Prithvi Simha

2016-03-01

Full Text Available To highlight the shortcomings in conventional methods of extraction, this study investigates the efficacy of Microwave Assisted Extraction (MAE toward bioactive compound recovery from pharmaceutically-significant medicinal plants, Adathoda vasica and Cymbopogon citratus. Initially, the microwave (MW drying behavior of the plant leaves was investigated at different sample loadings, MW power and drying time. Kinetics was analyzed through empirical modeling of drying data against 10 conventional thin-layer drying equations that were further improvised through the incorporation of Arrhenius, exponential and linear-type expressions. 81 semi-empirical Midilli equations were derived and subjected to non-linear regression to arrive at the characteristic drying equations. Bioactive compounds recovery from the leaves was examined under various parameters through a comparative approach that studied MAE against Soxhlet extraction. MAE of A. vasica reported similar yields although drastic reduction in extraction time (210 s as against the average time of 10 h in the Soxhlet apparatus. Extract yield for MAE of C. citratus was higher than the conventional process with optimal parameters determined to be 20 g sample load, 1:20 sample/solvent ratio, extraction time of 150 s and 300 W output power. Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy were performed to depict changes in internal leaf morphology.

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...

Hypotensive and vasorelaxant effects of citronellol, a monoterpene alcohol, in rats.

Science.gov (United States)

Bastos, Joana F A; Moreira, Italo J A; Ribeiro, Thaís P; Medeiros, Isac A; Antoniolli, Angelo R; De Sousa, Damião P; Santos, Márcio R V

2010-04-01

Citronellol is an essential oil constituent from the medicinal plants Cymbopogon citratus, Cymbopogon winterianus and Lippia alba which are thought to possess antihypertensive properties. Citronellol-induced cardiovascular effects were evaluated in this study. In rats, citronellol (1-20 mg/kg, i.v.) induced hypotension, which was not affected by pre-treatment with atropine, hexamethonium, N(omega)-nitro-L-arginine methyl ester hydrochloride or indomethacin, and tachycardia, which was only attenuated by pre-treatment with atropine and hexamethonium. These responses were less than those obtained for nifedipine, a reference drug. In intact rings of rat mesenteric artery pre-contracted with 10 microM phenylephrine, citronellol induced relaxations (pD(2) = 0.71 +/- 0.11; E(max) = 102 +/- 5%; n = 6) that were not affected by endothelium removal, after tetraethylamonium in rings without endothelium pre-contracted with KCl 80 mM. Citronellol strongly antagonized (maximal inhibition = 97 +/- 4%; n = 6) the contractions induced by CaCl(2) (10(-6) to 3 x 10(-3 )M) and did not induce additional effects on the maximal response of nifedipine (10 microM). Finally, citronellol inhibited the contractions induced by 10 microM phenylephrine or 20 mM caffeine. The present results suggest that citronellol lowers blood pressure by a direct effect on the vascular smooth muscle leading to vasodilation.

Essential oils on the control of stem and ear rot in maize

Directory of Open Access Journals (Sweden)

Glauco Antonio Teixeira

2013-11-01

Full Text Available Stem and ear rot caused by Stenocarpella maydis are responsible for severe losses in maize production. Treatment of seeds with fungicides may induce environmental damage. Hence, this study aimed to evaluate the effects of essential oils extracted from Cymbopogon winterianus, Thymus vulgaris, Cymbopogon citratus, Corymbia citriodora, Cinnamomum zeylanicum, and Syzygium aromaticum on the development of in vitro S. maydis. In addition, maize seeds were treated with these essential oils to determine their possible mode of action and effects. The oils from S. aromaticum, C. zeylanicum, and T. vulgaris inhibited fungal development at concentrations higher than 0.025%. The oils from S. aromaticum and C. zeylanicum showed seed germination rates of 89.0% and 84.5%, which were higher than that of the control. The oils from S. aromaticum and C. zeylanicum reduced the pathogen incidence in the seeds to 39.0% and 28.0%, respectively. Further, these oils as well as that from T. vulgaris produced lower reduction of maize stand. Scanning electron microscopy examination revealed that essential oils from S. aromaticum and T. vulgaris acted directly on the conidia, impeding germination. The findings suggest that the oils from S. aromaticum, C. zeylanicum, and T. vulgaris are potential alternatives for maize seed treatment in the control of S. maydis.

Essential Oils from Ugandan Aromatic Medicinal Plants: Chemical Composition and Growth Inhibitory Effects on Oral Pathogens

Directory of Open Access Journals (Sweden)

Francis Ocheng

2015-01-01

Full Text Available The study assessed the growth inhibitory effects of essential oils extracted from ten Ugandan medicinal plants (Bidens pilosa, Helichrysum odoratissimum, Vernonia amygdalina, Hoslundia opposita, Ocimum gratissimum, Cymbopogon citratus, Cymbopogon nardus, Teclea nobilis, Zanthoxylum chalybeum, and Lantana trifolia used traditionally in the management of oral diseases against oral pathogens. Chemical compositions of the oils were explored by GC-MS. Inhibitory effects of the oils were assessed on periodontopathic Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans and cariogenic Streptococcus mutans and Lactobacillus acidophilus using broth dilution methods at concentrations of 1%, 0.1%, and 0.01%. The most sensitive organism was A. actinomycetemcomitans. Its growth was markedly inhibited by six of the oils at all the concentrations tested. Essential oil from C. nardus exhibited the highest activity with complete growth inhibition of A. actinomycetemcomitans and P. gingivalis at all the three concentrations tested, the major constituents in the oil being mainly oxygenated sesquiterpenes. Most of the oils exhibited limited effects on L. acidophilus. We conclude that essential oils from the studied plants show marked growth inhibitory effects on periodontopathic A. actinomycetemcomitans and P. gingivalis, moderate effects on cariogenic S. mutans, and the least effect on L. acidophilus. The present study constitutes a basis for further investigations and development of certain oils into alternative antiplaque agents.

Essential Oils from Ugandan Aromatic Medicinal Plants: Chemical Composition and Growth Inhibitory Effects on Oral Pathogens

Science.gov (United States)

Ocheng, Francis; Bwanga, Freddie; Joloba, Moses; Softrata, Abier; Azeem, Muhammad; Pütsep, Katrin; Borg-Karlson, Anna-Karin; Obua, Celestino; Gustafsson, Anders

2015-01-01

The study assessed the growth inhibitory effects of essential oils extracted from ten Ugandan medicinal plants (Bidens pilosa, Helichrysum odoratissimum, Vernonia amygdalina, Hoslundia opposita, Ocimum gratissimum, Cymbopogon citratus, Cymbopogon nardus, Teclea nobilis, Zanthoxylum chalybeum, and Lantana trifolia) used traditionally in the management of oral diseases against oral pathogens. Chemical compositions of the oils were explored by GC-MS. Inhibitory effects of the oils were assessed on periodontopathic Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans and cariogenic Streptococcus mutans and Lactobacillus acidophilus using broth dilution methods at concentrations of 1%, 0.1%, and 0.01%. The most sensitive organism was A. actinomycetemcomitans. Its growth was markedly inhibited by six of the oils at all the concentrations tested. Essential oil from C. nardus exhibited the highest activity with complete growth inhibition of A. actinomycetemcomitans and P. gingivalis at all the three concentrations tested, the major constituents in the oil being mainly oxygenated sesquiterpenes. Most of the oils exhibited limited effects on L. acidophilus. We conclude that essential oils from the studied plants show marked growth inhibitory effects on periodontopathic A. actinomycetemcomitans and P. gingivalis, moderate effects on cariogenic S. mutans, and the least effect on L. acidophilus. The present study constitutes a basis for further investigations and development of certain oils into alternative antiplaque agents. PMID:26170872

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...

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

Lipase inhibitory activity of Carica papaya, Chrysophyllum cainito, Corcorus olitorius, Cympogon citrates and Syzygium cumini extracts

Directory of Open Access Journals (Sweden)

Briones, A.T.

2017-09-01

Full Text Available The lipase inhibitory action of Carica papaya, Chrysophyllum cainito, Corcorus olitorius, Cymbopogon citrates and Syzygium cumini were evaluated to explore for the presence of anti-obesity compounds and their potential weight-lowering activity. Enzyme inhibition results of the alcoholic extracts of the five plants showed that C. cainito has the highest percent inhibition at 74.91% while S. cumini, C. citratus, C. olitorius and C. papaya obtained less than 50% average inhibition. C. cainito was partitioned using hexane and ethyl acetate to further concentrate the bioactive compounds. The lipase inhibition assay of hexane and ethyl acetate extracts showed 92.11% inhibition and 21.9% inhibition, respectively. The greater activity in the former may imply that majority of potential anti-lipase constituents are found in the hexane portion.

In Vitro Antibacterial Activity of Essential Oils against Streptococcus pyogenes

Directory of Open Access Journals (Sweden)

Julien Sfeir

2013-01-01

Full Text Available Streptococcus pyogenes plays an important role in the pathogenesis of tonsillitis. The present study was conducted to evaluate the in vitro antibacterial activities of 18 essential oils chemotypes from aromatic medicinal plants against S. pyogenes. Antibacterial activity of essential oils was investigated using disc diffusion method. Minimum Inhibitory Concentration of essential oils showing an important antibacterial activity was measured using broth dilution method. Out of 18 essential oils tested, 14 showed antibacterial activity against S. pyogenes. Among them Cinnamomum verum, Cymbopogon citratus, Thymus vulgaris CT thymol, Origanum compactum, and Satureja montana essential oils exhibited significant antibacterial activity. The in vitro results reported here suggest that, for patients suffering from bacterial throat infections, if aromatherapy is used, these essential oils, considered as potential antimicrobial agents, should be preferred.

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

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...

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

Directory of Open Access Journals (Sweden)

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.

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

Directory of Open Access Journals (Sweden)

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.

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...

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...

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.

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...

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.

Análise de taninos totais em plantas aromáticas e medicinais cultivadas no Nordeste do Rio Grande do Sul

Directory of Open Access Journals (Sweden)

M.R. Pansera

Full Text Available Os taninos são componentes polifenólicos encontrados em plantas, alimentos e bebidas, sendo utilizados como fonte de matéria-prima para várias indústrias, como por exemplo a farmacêutica e a alimentícia, no curtimento do couro, na produção de borrachas, no tratamento de água em barragens, entre outras. Em vista da importância deste grupo de compostos, algumas plantas aromáticas e medicinais cultivadas no Núcleo Agronômico do Instituto de Biotecnologia da Universidade de Caxias dos Sul foram avaliadas quanto ao teor de taninos totais: Angelica archangelica , Cinnamomun camphora var. linaloolifera fugita , Cymbopogon citratus, Lavandula dentata , Lippia alba, Rosmarinus officinalis e Thymus vulgaris, e esses foram comparados com o teor de taninos totais da Acacia mearnsii (acácia negra, planta utilizada para a extração de taninos. O processo de extração empregado foi a maceração com metanol e a quantificação foi realizada por espectrofotometria, utilizando-se o reagente de Folin Denis. A partir da curva de calibração (% equivalente ao ácido tânico foram obtidos os teores de taninos totais, que variaram de 0,01% para Cymbopogom citratus a 18,9% para Lippia alba.

Inhibitory action of some essential oils and phytochemicals on the growth of various moulds isolated from foods

Directory of Open Access Journals (Sweden)

Evandro Leite de Souza

2005-03-01

Full Text Available The aim of this study was to determine the sensitivity profile of mould strains isolated from foods to some essential oils and phytochemicals. The assayed mould strains were: Fusarium spp., Rhizopus spp., Aspergillus flavus, A. niger and Penicillium spp. According to results, Lippia alba N.E. Brown, Peumus boldus Molina, Lippia microphylla Phil., Citrus limon Risso and Cymbopogon citratus Stapf. essential oil and the phytochemicals citral, eugenol and mircene showed prominent antimould activity. Among the products that evidenced antimould activity, citral and eugenol showed the lowest minimum inhibitory concentrations, which was 1% and 4%, respectively, for the most of the tested mould strains.O objetivo deste estudo foi determinar o perfil de sensibilidade de cepas de fungos filamentosos isolados de alimento a alguns óleos essenciais e fitoconstituintes. As cepas fúngicas utilizadas nos ensaios antimicrobianos foram: Fusarium spp., Rhizopus spp., Aspergillus flavus, A. niger e Penicillium spp. De acordo com os resultados obtidos, os óleos essenciais de L. Alba N.R. Brown, P. boldus Molina, L. microphylla Phill, C. limon Risso e C. citratus Stapf. e os fitoconstituintes citral, eugenol e mirceno mostraram destacada atividade antifúngica. Dentre os produtos que apresentaram atividade antifúngica, o citral e eugenol mostraram as menores CIM's, as quais foram 1% e 4%, respectivamente, para a maioria das cepas fúngicas testadas.

Evaluation of five essential oils from aromatic plants of Cameroon for controlling food spoilage and mycotoxin producing fungi.

Science.gov (United States)

Nguefack, J; Leth, V; Amvam Zollo, P H; Mathur, S B

2004-08-01

Five essential oils (EO) extracted from Cymbopogon citratus, Monodora myristica, Ocimum gratissimum, Thymus vulgaris and Zingiber officinale were investigated for their inhibitory effect against three food spoilage and mycotoxin producing fungi, Fusarium moniliforme, Aspergillus flavus and Aspergillus fumigatus. Five strains of each fungus were tested. The agar dilution technique was used to determine the inhibitory effect of each EO on the radial growth of the fungus, and a dose response was recorded. The EO from O. gratissimum, T. vulgaris and C. citratus were the most effective and prevented conidial germination and the growth of all three fungi on corn meal agar at 800, 1000 and 1200 ppm, respectively. Moderate activity was observed for the EO from Z. officinale between 800 and 2500 ppm, while the EO from M. myristica was less inhibitory. These effects against food spoilage and mycotoxin producing fungi indicated the possible ability of each essential oil as a food preservative. A comparative test on the preservative ability of the EO from O. gratissimum and potassium sorbate against A. flavus at pH 3.0 and 4.5 showed that the EO remained stable at both pH, whereas the efficacy of potassium sorbate was reduced at higher pH. We concluded that the EO from O. gratissimum is a potential food preservative with a pH dependent superiority against potassium sorbate, and these are novel scientific information.

Influence of some plant extracts on the ovi-position behavior of Aedes fluviatilis and Culex quinquifasciatus

Directory of Open Access Journals (Sweden)

Abdulhakim A. El Maghrbi

2014-06-01

Full Text Available Alcoholic/acetone extracts of nine species of plants (Allium tuberosum, Apium leptophylum, Carica papaya, Cymbopogon citratus, Euphorbia cotinofolia, Melia azedarach, Ocimum canum, Ricinus communis and Tagetes erecta were tested in respect to their influence on the ovi-position behavior of the mosquito, Aedes fluviatilis and Culex quinquifasciatus in concentrations of 100, 10 and 1 mg/L. Three days after mosquito females had fed on blood of anesthetized mice and pigeon respectively, experimental and control dishes were placed into cages for 24 h then number of eggs laid in each dish was counted. Alcoholic/acetone extracts of C. papaya, C. citratus and T. erecta at 100 mg/L; E. cotinofolia and O. canum at 100 and 10 mg/L were proved to be repulsive for ovi-position of Ae. fluviatilis. On the other hand, acetone extracts of A. tuberosum and M. azederach at 100 and 10 mg/L; A. leptophyllum, O. canum, E. cotinofolia and R. communis at 100 mg/L produced same effect on ovi-position behavior of Ae. fluviatilis. Alcoholic extracts E. cotinofolia, R. communis (100 mg/L and M. azedarach (100 and 10 mg/L were attractive to Cx. quinquifasciatus. Five acetone extracts (A. tuberosum, A. leptophylum, C. papaya, C. Citrates and M. azedarach were repulsive for ovi-position at 100 mg/L. Acetone extract of A. tuberosum and M. azedarach at 10 and 1 mg/L and C. citratus at 10 mg/L maintained the same properties. Our results concluded that each plant extract has the potential to control ovi-position behavior of mosquito. The differences in obtained responses necessitate the adoption of deeper research to isolate the active principle of such plants for potential use in mosquito control program.

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...

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...

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...

Development of shampoo, soap and ointment formulated by green synthesised silver nanoparticles functionalised with antimicrobial plants oils in veterinary dermatology: treatment and prevention strategies.

Science.gov (United States)

Bansod, Sunita Dashrath; Bawaskar, Manisha Subrashrao; Gade, Aniket Krishnarao; Rai, Mahendra Kumar

2015-08-01

Many scientists have focused their research on the role of nanotechnology for the control of human pathogens, but there are also many topical pathogens present in animals, which infect animals and transfer to humans. Topical therapy is extremely important for the management of dermatological condition in animals. Therefore, the present study aims to evaluate the efficacy of biogenic silver nanoparticles (AgNPs) in combination with herbal oils against animal skin infections which may be responsible for causing infections in human beings. Here, the authors synthesised and characterised the AgNPs from Azadirachta indica. The oils were extracted from medicinal plants including Cymbopogon citratus, Cymbopogon martini, Eucalyptus globules, A. indica and Ocimum sanctum and the antifungal and antibacterial activity of plant oils along with AgNPs were evaluated. An excision wound model was used for the study of wound healing activity in rabbits. AgNPs functionalised oil has demonstrated remarkable antimicrobial activity against pathogens present on the skin of animals. The nano-functionalised antimicrobial oils were used in the formulation of shampoo, soap and ointment for veterinary dermatology. Antimicrobial products of plant origin with AgNPs are valuable, safe and have a specific role in controlling diseases. The authors believe that this approach will be a good alternative therapy to solve the continuous antibiotic resistance developed by many bacterial pathogens and will be utilised in various animal contacting areas in medicine.

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...

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.

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...

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.

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.

INSECTICIDAL ACTIVITIES OF ESSENTIAL OILS EXTRACTED FROM THREE SPECIES OF POACEAE ON ANOPHELES GAMBIAE SPP, MAJOR VECTOR OF MALARIA

Directory of Open Access Journals (Sweden)

Dominique C. K. Sohounhloué

2010-12-01

Full Text Available In this paper, the insecticidal activities on Anopheles gambiae spp of the essential oils (EO extracted from the dry leaves of some species collected in Benin were studied. The essential oil yields are 2.8, 1.7 and 1.4�0respectively for Cymbopogon schoanenthus (L. Spreng (CS, Cymbopogon citratus Stapf. (CC and Cymbopogon giganteus (Hochst. Chiov (CG. The GC/MS analysis showed that the EO of CS had a larger proportion in oxygenated monoterpenes (86.3�20whereas those of the sheets of CC and CG are relatively close proportions (85.5�0and 82.7�0respectively with. The piperitone (68.5�  2-carene (11.5� and -eudesmol (4.6�20are the major components of the EO of CS while trans para-mentha-1(7,8-dien-2-ol (31.9� trans para-mentha-2,8-dien-1-ol (19.6� cis para-mentha-2,8-dien-1-ol (7.2� trans piperitol (6.3�20and limonene (6.3�20prevailed in the EO of CG. The EO of CC revealed a rich composition in geranial (41.3� neral (33� myrcene (10.4� and geraniol (6.6� The biological tests have shown that these three EO induced 100�0mortality of Anopheles gambiae to 1.1, 586.58 and 1549 µg•cm-2 respectively for CC, CS and CG. These effects are also illustrated by weak lethal concentration for 50�0anopheles population (CC: 0.306; CS: 152.453 and CG: 568.327 µg•cm-2 in the same order of reactivity. The EO of CC appeared most active on two stocks (sensitive and resistant of Anopheles gambiae.

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

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.

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.

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...

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...

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....

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.

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.

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%

Fungitoxidade in vitro de extratos vegetais sobre Exserohilum turcicum (Pass Leonard & Suggs In vitro fungitoxicity of plant extracts on Exserohilum turcicum (Pass Leonard & Suggs

Directory of Open Access Journals (Sweden)

C.R Scapin

2010-03-01

Full Text Available A helmintosporiose, causada pelo fungo Exserohilum turcicum, é uma das principais doenças do milho-pipoca cultivado no Brasil. Devido às características da cultura, como porte da planta, extensão da área de plantio e rentabilidade econômica, o emprego de resistência genética e controle químico têm sido as principais formas de controle da doença. O emprego de agrotóxicos na agricultura tem levado riscos à saúde humana e freqüentes danos ao meio ambiente. Assim, na busca de métodos alternativos para o controle da helmintosporiose foi avaliado o efeito fungitóxico dos extratos vegetais das plantas Achillea milefollium (mil-folhas, Cymbopogon citratus (capim-limão, Artemisia camphorata (cânfora e Rosmarinus officinalis (alecrim no crescimento micelial de E. turcicum, em dois meios de cultura (BDA - batata-dextrose-ágar; e LCH - lactose caseína hidrolisada. Os extratos de alecrim e cânfora foram os que apresentaram maior inibição do crescimento micelial nos dois meios de cultura, enquanto que os extratos de mil-folhas e capim limão estimularam o crescimento micelial em meio LCH.Helminthosporiose is caused by the fungus Exserohilum turcicum and represents one of the main diseases in popcorn grown in Brazil. Due to its characteristics, such as plant size, planting area extension and economic profitability, the use of genetic resistance and chemical control has constituted the main procedure against such disease. The use of pesticides in agriculture has resulted in risks to the human health and frequent damages to the environment. Thus, the fungitoxic effect of plant extracts of Achillea millefolium (yarrow, Cymbopogon citratus (lemon grass, Artemisia camphorata (camphor and Rosmarinus officinalis (rosemary on the mycelial growth of E. turcicum was evaluated by using two culture media (PDA - potato dextrose agar, and LCH - lactose-casein hydrolysate in order to set alternative methods for controlling helminthosporiose. Rosemary

Efeito de solo previamente cultivado com plantas aromáticas na germinação e no desenvolvimento inicial de alface

Directory of Open Access Journals (Sweden)

T. S. PEREIRA

2015-12-01

Full Text Available RESUMOO objetivo desse trabalho foi verificar o efeito do solo pré-cultivado com plantas aromáticas na germinação e no desenvolvimento inicial de plântulas de alface cv. Simpson. A pesquisa foi realizada na Embrapa Hortaliças, Brasília, em bandejas mantidas em casa de vegetação. O experimento foi conduzido em delineamento experimental inteiramente casualizado, com três repetições e onze tratamentos: solo pré-cultivado com hortelã-comum (Mentha x villosa, hortelã-brava (Mentha arvensis, hortelã-pimenta (Mentha piperita, Mentha spp., capim-citronela (Cymbopogon winterianus, capim-limão (Cymbopogon citratus, manjericão de folha larga (Ocimum basilicum, manjericão de folha roxa (Ocimum gratissimun, tomilho (Thymus vulgaris, sálvia (Salvia officinalis e solo da mesma área sem cultivo prévio de planta aromática (controle. Aos 30 dias após o semeio, foram avaliadas: índice de velocidade de emergência (IVE, taxa de sobrevivência (TS, número de folhas (NF, comprimento da raiz principal (CRP e da parte aérea (CPA, massa fresca da raiz (MFR e da parte aérea (MFPA e massa seca da raiz (MSR e da parte aérea (MSPA. Os dados foram submetidos à análise de variância e teste de Tukey a 5% de probabilidade. Houve diferença significativa em relação ao IVE, sendo que o tratamento com C. citratus afetou negativamente a emergência das plântulas. O tratamento com M. arvensis apresentou uma TS de apenas 16% das plantas aos 30 dias após a semeadura. O NF foi menor no tratamento com M. arvensis, diferentemente de todos os demais, exceto S. officinalis. A MRF e MFF foram estimuladas pelo tratamento com T. vulgaris sendo superior a todos os outros tratamentos. Os resultados obtidos permitem concluir que houve efeito negativo de M. arvensis e positivo de T. vulgaris no desenvolvimento inicial de plântulas de alface.

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.

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...

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%.

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).

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

Directory of Open Access Journals (Sweden)

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.

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.

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)

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.

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.

Effect of agricultural inputs and essential oils on the soil of vegetables in Colombia's Caribbean region

Directory of Open Access Journals (Sweden)

Eduardo Mena-Rodríguez

2018-01-01

Full Text Available The contribution of vegetables to food security and economic development in Colombia, as well as to environmental problems worldwide, justifies the interest to design sustainable production strategies for the agro-chain. This study was developed to evaluate the effect of the application of essential oils and agricultural inputs in chili peppers, beans and eggplants in Codazzi, Cesar, Colombia. The methodology included the compatibility analysis between pesticides used in these vegetables, and Lippia alba and Cymbopogon citratus oils in relation to their biocidal effect in vitro on native strains of Macrophomina phaseolina, Phytophthora capsici and Colletotrichum gloeosporioides. Applications of thiabendazole in an individual basis and combined with oils were carried out in the field. Physicochemical and microbiological indicators of soil, pests and diseases incidence and crop yield were measured. Oils controlled up to 97% of plant pathogens in vitro and exhibited compatibility with carbendazim and thiabendazole. In the field, up to 67 % of disease control was observed with C. citratus + thiabendazole compared to the control (p = 0.00, yields were close to the regional average, and better microbiological and physicochemical soil conditions were observed. In conclusion, there are differences in the edaphic effect between treatments, as the agrochemical and the oil combinations were more favorable than the individual effect of each product on the variables evaluated. The above exhorts to continue soil evaluations with oils to elucidate the duration of the described effects.

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

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.

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

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.

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.

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.

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...

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...

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....

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...

Antifungal activity using medicinal plant extracts against pathogens of coffee tree

Directory of Open Access Journals (Sweden)

J.L. Silva

2014-09-01

Full Text Available Generally, the medicinal plants have antifungal substances that can be used for the plant protection against phytopathogens. The objective of this study was to know the efficiency of aqueous extracts from medicinal plants against the major etiological agents of coffee tree. The aqueous extracts used were extracted from bulbs of Allium sativum, leaves of Vernonia polysphaera, Cymbopogon citratus, Cymbopogon nardus, Cordia verbenacea, Eucalyptus citriodora, Ricinus communis, Azadirachta indica, Piper hispidinervum and flower buds of Syzygium aromaticum. The etiological agents considered for this study were Cercospora coffeicola, Colletotrichum gloeosporioides, Fusarium oxysporum, Phoma tarda, Rhizoctonia solani and Hemileia vastatrix. The screening for harmful extracts was done based on mycelial growth and conidial germination inhibition. All experiments performed were in vitro conditions. The inhibition of mycelial growth was performed mixing the extracts with the PDA. This mixture was poured in Petri dishes. On the center of the dishes was added one PDA disc with mycelium. It was incubated in a chamber set to 25ºC. The evaluation was done daily by measuring the mycelial growth. The germination assessment was also performed with Petri dishes containing agar-water medium at 2%. These were incubated at 25ºC for 24 hours. After this period the interruption of germination was performed using lactoglycerol. The experiments were conducted in a completely randomized design. The most effective plant extracts against the micelial growth and conidial germination were V. polysphaera, S. aromaticum and A. sativum.

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.

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....

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…

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...

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.

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.

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...

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.

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.

Densidades de plantio e doses de biofertilizante na produção de capim-limão Density and biofertilizer levels for lemon grass production

Directory of Open Access Journals (Sweden)

Arie F Blank

2007-09-01

Full Text Available O objetivo do trabalho foi avaliar o efeito de densidades de plantio e doses de biofertilizante comercial na produção de capim-limão (Cymbopogon citratus (D.C. Stapf. O experimento foi implantado em parcelas subdivididas com três repetições, colocando-se nas parcelas as densidades de plantio (33.333, 49.382, 55.555 e 111.111 plantas ha-1 e nas subparcelas as doses de biofertilizante (0; 20; 40 e 60 t ha-1. Foram realizadas nove colheitas em intervalos de 42 dias. Avaliou-se a sobrevivência, a altura de planta, o número de perfilhos por touceira, a massa seca por touceira e da parte aérea, o teor e o rendimento de óleo essencial. O teor de óleo essencial não foi influenciado pelas densidades de plantio e doses de biofertilizante. A densidade crescente resultou em regressões lineares crescentes para o rendimento de óleo essencial e a massa seca da parte aérea e em uma regressão linear decrescente para a massa seca por touceira. A dose de biofertilizante resultou em regressões lineares crescentes para o rendimento de óleo essencial e a massa seca por touceira e da parte aérea. A densidade de 111.111 plantas ha-1 (0,30 x 0,30 m e a dose de biofertilizante de 60 t ha-1 no primeiro ano de cultivo poderão ser recomendados para produção do capim-limão.The aim of this work was to evaluate the plant density and biofertilizer levels on lemon grass (Cymbopogom citratus (D.C. Stapf. The experiment was installed in split plot design with three replications, having plant density as plots (33,333; 49,382; 55,555 and 111,111 plants ha-1 and biofertilizer doses as sub plots (0; 20; 40; 60 t ha-1 year-1. Nine cuttings were realized using an interval of 42 days between cuttings. We evaluated survival, plant height, number of tillers per plant, dry weight per plant and of biomass yield, essential oil content and yield. The essential oil content was not influenced by the plant densities and biofertilizer doses. The crescent density resulted in

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.

Ação e caracterização química de óleos essenciais no manejo da antracnose do maracujá

Directory of Open Access Journals (Sweden)

César Fernandes Aquino

2012-12-01

Full Text Available Objetivou-se avaliar dois métodos de inoculação de Colletotrichum gloeosporioides em maracujá, testar a patogenicidade de diferentes isolados, o efeito fungitóxico e a composição química dos óleos essenciais das espécies medicinais alecrim-pimenta (Lippia sidoides Cham., capim-santo [Cymbopogon citratus (D. C. Stapf.], alfavaca-cravo (Ocimum gratissimum L., no controle da antracnose [Colletotrichum gloeosporioides (Penz.], associado ao estádio de maturação de frutos de maracujazeiro-amarelo. Avaliaram-se três experimentos, onde se testou a patogenicidade de seis isolados do fungo em delineamento inteiramente casualizado, com seis repetições, outro com o mesmo delineamento em esquema fatorial 2x2 (suspensão de conídios e disco de micélio e frutos (verdes e maduros, com seis repetições. No tratamento com frutos, utilizou-se o delineamento inteiramente casualizado, em esquema fatorial 5x3+1, sendo cinco concentrações (0; 2; 4; 6 e 8µL mL-1 e três espécies medicinais, mais o tebuconazol, com cinco repetições. Fez-se a caracterização química dos óleos por cromatografia gasosa, com espectrometria de massas. Todos os isolados foram patogênicos. Os frutos maduros apresentaram maior diâmetro das lesões, quando inoculados com suspensão de conídios. O óleo de C. citratus proporcionou o menor diâmetro das lesões nos frutos, até a concentração de 6 µL mL-1. Na concentração de 8 µL mL-1, todos os óleos inibiram o desenvolvimento do fungo. O timol (30,24%, o citral (77,74% e o eugenol (92,89% foram componentes majoritários em L. sidoides, C. citratus e O. gratissimum, respectivamente.

Screening of anti-dengue activity in methanolic extracts of medicinal plants

Directory of Open Access Journals (Sweden)

Tang Leon IC

2012-01-01

Full Text Available Abstract Background Dengue fever regardless of its serotypes has been the most prevalent arthropod-borne viral diseases among the world population. The development of a dengue vaccine is complicated by the antibody-dependent enhancement effect. Thus, the development of a plant-based antiviral preparation promises a more potential alternative in combating dengue disease. Methods Present studies investigated the antiviral effects of standardised methanolic extracts of Andrographis paniculata, Citrus limon, Cymbopogon citratus, Momordica charantia, Ocimum sanctum and Pelargonium citrosum on dengue virus serotype 1 (DENV-1. Results O. sanctum contained 88.6% of total flavonoids content, an amount that was the highest among all the six plants tested while the least was detected in M. charantia. In this study, the maximum non-toxic dose (MNTD of the six medicinal plants was determined by testing the methanolic extracts against Vero E6 cells in vitro. Studies also determined that the MNTD of methanolic extract was in the decreasing order of M. charantia >C. limon >P. citrosum, O. sanctum >A. paniculata >C. citratus. Antiviral assay based on cytopathic effects (CPE denoted by degree of inhibition upon treating DENV1-infected Vero E6 cells with MNTD of six medicinal plants showed that A. paniculata has the most antiviral inhibitory effects followed by M. charantia. These results were further verified with an in vitro inhibition assay using MTT, in which 113.0% and 98.0% of cell viability were recorded as opposed to 44.6% in DENV-1 infected cells. Although methanolic extracts of O. sanctum and C. citratus showed slight inhibition effect based on CPE, a significant inhibition was not reflected in MTT assay. Methanolic extracts of C. limon and P. citrosum did not prevent cytopathic effects or cell death from DENV-1. Conclusions The methanol extracts of A. paniculata and M. charantia possess the ability of inhibiting the activity of DENV-1 in in vitro assays

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)

Lemongrass effects on IL-1beta and IL-6 production by macrophages.

Science.gov (United States)

Sforcin, J M; Amaral, J T; Fernandes, A; Sousa, J P B; Bastos, J K

2009-01-01

Cymbopogon citratus has been widely recognised for its ethnobotanical and medicinal usefulness. Its insecticidal, antimicrobial and therapeutic properties have been reported, but little is known about its effect on the immune system. This work aimed to investigate the in vivo effect of a water extract of lemongrass on pro-inflammatory cytokine (IL-1beta and IL-6) production by macrophages of BALB/c mice. The action of lemongrass essential oil on cytokine production by macrophages was also analysed in vitro. The chemical composition of the extract and the oil was also investigated. Treatment of mice with water extract of lemongrass inhibited macrophages to produce IL-1beta but induced IL-6 production by these cells. Lemongrass essential oil inhibited the cytokine production in vitro. Linalool oxide and epoxy-linalool oxide were found to be the major components of lemongrass water extract, and neral and geranial were the major compounds of its essential oil. Taken together, these data suggest an anti-inflammatory action of this natural product.

Synergism between plant extract and antimicrobial drugs used on Staphylococcus aureus diseases

Directory of Open Access Journals (Sweden)

Joyce Elaine Cristina Betoni

2006-06-01

Full Text Available Searches for substances with antimicrobial activity are frequent, and medicinal plants have been considered interesting by some researchers since they are frequently used in popular medicine as remedies for many infectious diseases. The aim of this study was to verify the synergism between 13 antimicrobial drugs and 8 plant extracts - "guaco" (Mikania glomerata, guava (Psidium guajava, clove (Syzygium aromaticum, garlic (Allium sativum, lemongrass (Cymbopogon citratus, ginger (Zingiber officinale, "carqueja" (Baccharis trimera, and mint (Mentha piperita - against Staphylococcus aureus strains, and for this purpose, the disk method was the antimicrobial susceptibility test performed. Petri dishes were prepared with or without dilution of plant extracts at sub-inhibitory concentrations in Mueller-Hinton Agar (MHA, and the inhibitory zones were recorded in millimeters. In vitro anti-Staphylococcus aureus activities of the extracts were confirmed, and synergism was verified for all the extracts; clove, guava, and lemongrass presented the highest synergism rate with antimicrobial drugs, while ginger and garlic showed limited synergistic capacity.

Chemical composition and antioxidant and anti-Listeria activities of essential oils obtained from some Egyptian plants.

Science.gov (United States)

Viuda-Martos, Manuel; El Gendy, Abd El-Nasser G S; Sendra, Esther; Fernández-López, Juana; Abd El Razik, K A; Omer, Elsayed A; Pérez-Alvarez, Jose A

2010-08-25

The aim of this work was to (i) determine the chemical composition of the essential oils of six spices widely cultivated in Egypt (Origanum syriacum, Majorana hortensis, Rosmarinus officinalis, Cymbopogon citratus, Thymus vulgaris, and Artemisia annua); (ii) determine the antioxidant activity of the Egyptian essential oils by means of five different antioxidant tests; and (iii) determine the effectiveness of these essential oils on the inhibition of Listeria innocua CECT 910. There is a great variability in the chemical composition of essential oils obtained from the six Egyptian aromatic plants. Overall, thyme (highest percentage of inhibition of DPPH radical: 89.40%) and oregano (highest percentage of inhibition of TBARS: 85.79) essential oils presented the best antioxidant profiles, whereas marjoram, lemongrass, and artemisia were highly effective in metal chelating but had a pro-oxidative behavior by Rancimat induction test. Lemongrass essential oil showed the highest antibacterial activity against L. innocua with an inhibition zone of 49.00 mm, followed in effectiveness by thyme, marjoram, and oregano.

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.

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...

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...

Sliding-Mode Control of a Charger/Discharger DC/DC Converter for DC-Bus Regulation in Renewable Power Systems

Directory of Open Access Journals (Sweden)

Sergio Ignacio Serna-Garcés

2016-03-01

Full Text Available Stand-alone power systems based on renewable energy sources are used to replace generators based on fossil fuels. Those renewable power systems also require Energy Storage Devices (ESD interfaced by a charger/discharger power converter, which consist of a bidirectional DC/DC converter, and a DC bus. This paper proposes a single sliding-mode controller (SMC for the charger/discharger DC/DC converter to provide a stable DC bus voltage in any operation condition: charging or discharging the ESD, or even without any power exchange between the ESD and the DC bus. Due to the non-linear nature of the power converter, the SMC parameters are adapted on-line to ensure global stability in any operation condition. Such stability of the adaptive SMC is mathematically demonstrated using analytical expressions for the transversality, reachability and equivalent control conditions. Moreover, a design procedure for the adaptive SMC parameters is provided in order to ensure the dynamic response required for the correct operation of the load. Finally, simulations and experimental tests validate the proposed controller and design procedure.

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...

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.

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.

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...

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...

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...

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.

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

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...

Interdependence of soil and agricultural practice in a two - year phytoremediation in situ experiment

Science.gov (United States)

Nwaichi, Eucharia; Onyeike, Eugene; Frac, Magdalena; Iwo, Godknows

2016-04-01

A two - year plant - based soil clean - up was carried out at a crude oil spill agricultural site in a Niger Delta community in Nigeria to access further clean - up potentials of Cymbopogon citratus. Applied diagnostic ratios identified mixed petrogenic and pyrogenic sources as the main contributors of PAHs. Up to 90.8% sequestration was obtained for carcinogenic PAHs especially Benz (a) pyrene in a 2 - phase manner. A community level approach for assessing patterns of sole carbon source utilization by mixed microbial samples was employed to differentiate spatial and temporal changes in the soil microbial communities. In relation to pollution, soil conditioning notably decreased the lag times and showed mixed effects for colour development rates, maximum absorbance and the overall community pattern. For rate and utilization of different carbon substrates in BIOLOG wells, after day 3, in comparison to control soil communities, contamination with hydrocarbons and associated types increased amines and amides consumption. Consumption of carbohydrates in all polluted and unamended regimes decreased markedlyin comparison to those cultivated with C. citratus. We found a direct relationship between cellulose breakdown, measurable with B-glucosidase activity, organic matter content and CO2 realease within all soils in the present study. Organic amendment rendered most studied contaminants unavailable for uptake in preference to inorganic fertilizer in both study years. Generally, phytoremediation improved significantly the microbial community activity and thus would promote ecosystem restoration in relation to most patronised techniques. Supplementation with required nutrients, in a long - term design would present many ecological benefits. Keywords: Agricultural soils; Recovery; Hydrocarbon pollution; Ecology; Management practice.

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.

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.

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.

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...

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...

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.

Design and formulation of a topical hydrogel integrating lemongrass-loaded nanosponges with an enhanced antifungal effect: in vitro/in vivo evaluation

Directory of Open Access Journals (Sweden)

Aldawsari HM

2015-01-01

Full Text Available Hibah M Aldawsari,1 Shaimaa M Badr-Eldin,1,2 Gihan S Labib,1,3 Amal H El-Kamel3 1Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, King Abdulaziz University, Jeddah, Saudi Arabia; 2Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Cairo University, Cairo, Egypt; 3Department of Pharmaceutics, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt Abstract: Lemongrass oil (LGO is a volatile oil extracted from the leaves of Cymbopogon citratus that has become one of the most important natural oils in the pharmaceutical industry because of its diverse pharmacologic and clinical effects. However, LGO suffers from low aqueous solubility, which could lead to a reduced effect. Moreover, the instability of its major active constituent, citral, could lead to volatilization, reaction with other formulation ingredients, and consequently, skin irritation. To surmount these problems, this research aims to formulate lemongrass-loaded ethyl cellulose nanosponges with a topical hydrogel with an enhanced antifungal effect and decreased irritation. The minimal inhibitory concentration and minimal fungicidal concentration of LGO against Candida albicans strain ATC 100231, determined using the broth macrodilution method, were found to be 2 and 8 µL/mL, respectively. The emulsion solvent evaporation technique was used for the preparation of the nanosponges. The nanosponge dispersions were then integrated into carbopol hydrogels (0.4%. Nine formulations were prepared based on a 32 full factorial design employing the ethyl cellulose:polyvinyl alcohol ratio and stirring rate as independent variables. The prepared formulations were evaluated for particle size, citral content, and in vitro release. Results revealed that all the nanosponge dispersions were nanosized, with satisfactory citral content and sustained release profiles. Statistical analysis revealed that both ethyl cellulose:polyvinyl alcohol ratio and

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.

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.

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.

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...

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.

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...

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...

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...

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.

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.

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.

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.

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.

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.

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...

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...

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.

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.

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

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.

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...

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.

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.

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.

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.

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.

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)

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....

Fumigant toxicity of plant essential oils against Camptomyia corticalis (Diptera: Cecidomyiidae).

Science.gov (United States)

Kim, Jun-Ran; Haribalan, Perumalsamy; Son, Bong-Ki; Ahn, Young-Joon

2012-08-01

The toxicity of 98 plant essential oils against third instars of cecidomyiid gall midge Camptomyia corticalis (Loew) (Diptera: Cecidomyiidae) was examined using a vapor-phase mortality bioassay. Results were compared with that of a conventional insecticide dichlorvos. Based on 24-h LC50 values, all essential oils were less toxic than dichlorvos (LC50, 0.027 mg/cm3). The LC50 of caraway (Carum carvi L.) seed, armoise (Artemisia vulgaris L.), clary sage (Salvia sclarea L.), oregano (Origanum vulgare L.), lemongrass [Cymbopogon citratus (DC.) Stapf], niaouli (Melaleuca viridiflora Gaertner), spearmint (Mentha spicata L.), cassia especial (Cinnamomum cassia Nees ex Blume), Dalmatian sage (Salvia offcinalis L.), red thyme (Thymus vulgaris L.), bay [Pimenta racemosa (P. Mill.) J.W. Moore], garlic (Allium sativum L.), and pennyroyal (Mentha pulegium L.) oils is between 0.55 and 0.60 mg/cm3. The LC50 of cassia (C. cassia, pure and redistilled), white thyme (T. vulgaris), star anise (Illicium verum Hook.f.), peppermint (Mentha X piperita L.), wintergreen (Gaultheria procumbens L.), cinnamon (Cinnamomum zeylanicum Blume) bark, sweet marjoram (Origanum majorana L.), Roman chamomile [Chamaemelum nobile (L.) All.], eucalyptus (Eucalyptus globulus Labill.), rosemary (Rosmarinus officinalis L.),Virginian cedarwood (Juniperus virginiana L.), pimento berry [Pimenta dioica (L.) Merr.], summer savory (Satureja hortensis L.), lavender (Lavandula angustifolia Mill.), and coriander (Coriandrum sativum L.) oils is between 0.61 and 0.99 mg/cm3. All other essential oils tested exhibited low toxicity to the cecidomyiid larvae (LC50, >0.99 mg/cm3). Global efforts to reduce the level of highly toxic synthetic insecticides in the agricultural environment justify further studies on the active essential oils as potential larvicides for the control of C. corticalis populations as fumigants with contact action.

Aprendizagem e memória de Telenomus podisi (Hymenoptera, Platygastridae

Directory of Open Access Journals (Sweden)

Roberta Tognon

2013-09-01

Full Text Available O parasitoide de ovos Telenomus podisi Ashmead, 1893 é um importante agente de controle natural de percevejos e seu sucesso de parasitismo está associado à habilidade para a localização do hospedeiro, sendo a aprendizagem e a memória um dos fatores que podem influenciar esta interação. O trabalho avaliou a capacidade de aprendizagem e tempo de retenção da memória de T. podisi ao extrato de capim-limão [Cymbopogon citratus (DC. Stapf. (Poales, Poaceae], em diferentes estágios do desenvolvimento da fase imatura. Ovos de Euschistus heros (Fabricius, 1798 (Hemiptera, Pentatomidae parasitados por T. podisi foram individualizados em tubos de vidro contendo papel filtro com extrato de capim-limão ou solvente acetona (controle e mantidos em diferentes estágios do desenvolvimento jovem dos parasitoides. Após a emergência, fêmeas de T. podisi foram testadas em olfatômetro tipo "Y" aos odores de ambos tratamentos. Fêmeas inexperientes foram submetidas aos mesmos odores das experientes. Para avaliar a memória, fêmeas oriundas de ovos que permaneceram em contato com o extrato de capim-limão por todo o desenvolvimento do estágio imaturo, foram testadas, após 24, 48, 72 e 96 horas de idade ao odor de capim-limão e acetona. Fêmeas que permaneceram em contato com o capim-limão por toda a fase jovem, direcionaram-se preferencialmente para este extrato, diferente das inexperientes ou das expostas à acetona, as quais preferiram o solvente. A presença do capim-limão, durante todo o estágio do desenvolvimento imaturo, alterou a orientação quimiotáxica de T. podisi, desencadeando aprendizagem nestes organismos, a qual se manteve por até 72 horas.

Plantas medicinais utilizadas pela população do município de Lagarto- SE, Brasil – ênfase em pacientes oncológicos

Directory of Open Access Journals (Sweden)

N.L.B. CAETANO

2015-01-01

Full Text Available RESUMO A utilização de plantas com fins medicinais é uma das mais antigas formas de prática medicinal da humanidade. Entretanto, o conceito de “natural” contribui para o pensamento popular e errôneo de que Plantas Medicinais (PM são sinônimos de produtos seguros, o qual pode ocasionar no desenvolvimento de efeitos adversos ou interações medicamentosas. Neste contexto, foi realizado levantamento etnofarmacológico das Plantas Medicinais (PM utilizadas no município de Lagarto, SE, Brasil, com ênfase de seu uso por pacientes oncológicos. Um total de 706 moradores foram entrevistados. Foram citadas 80 plantas, das quais 57 foram identificadas em nosso laboratório. O uso de plantas medicinais (MP para fins terapêuticos foi relatada por 336 (47,65% entrevistados. As MPs mais utilizados foram: Erva-Cidreira (Lippiaalba (Mill N. E. Brown - 103, 30,8%, Boldo (Plectranthus barbatus Andr. - 53, 15,7%, e Capim-Santo (Cymbopogon citratus (D.C. Stapf - 49, 14,6%. Dos entrevistados que relataram o uso de MPs, metade (360, 50,95% comunicaram ao médico, mas não receberam orientações específicas. As doenças crônicas mais comuns identificadas foram: hipertensão arterial (144, 20,34%, câncer (55, 7,81% e diabetes (41, 5,89%. Dos pacientes com câncer, cerca de 40% (22 relataram utilizar PMs concomitante com quimioterapia, dado alarmante, visto a possibilidade de interações medicamentosas entre PMs e antineoplásicos. Diante desses dados, foi observado o uso de PM pela população de Lagarto, SE, e por pacientes oncológicos dessa região, porém, sem os mesmos receberem orientações de um profissional qualificado.

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...

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.

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.

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.

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.

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....

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

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.

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...

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.

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.

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.

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...

Inhibitory effect of formulated lemongrass shampoo on Malassezia furfur: a yeast associated with dandruff.

Science.gov (United States)

Wuthi-Udomlert, Mansuang; Chotipatoomwan, Ployphand; Panyadee, Sasikan; Gritsanapan, Wandee

2011-03-01

Lemongrass (Cymbopogon citratus Stapf) has been used in cooking and in many traditional medicines; the essential oil contains citral as a major constituent. This study evaluated the antifungal activity of lemongrass oil against Malassezia furfur, an opportunistic yeast associated with dandruff, by using a broth dilution assay. From the minimum fungicidal concentration (MFC) obtained, the oil was then incorporated at different percentages into shampoo formulations. The formulated shampoos were kept at room temperature (28 degrees-30 degrees C) and under accelerated condition (45 degrees C). At the end of the first and sixth weeks, after preparation, all formulations were tested again and the appearance was recorded. Selection of an appropriate formula was based on antifungal activity against M. furfur, the physical appearance, the chemical properties and stability of the formula. Two percent lemongrass oil shampoo provided the required qualities necessary for commercial use. After being kept for 6 weeks at 28 degrees-30 degrees C and 45 degrees C, this formulated shampoo gave MFCs against M. furfur of 75 microl/ml and 18.75 microl/ml, respectively.

Reduction of Aeromonas hidrophyla biofilm on stainless stell surface by essential oils

Science.gov (United States)

Millezi, Alessandra Farias; Cardoso, Maria das Graças; Alves, Eduardo; Piccoli, Roberta Hilsdorf

2013-01-01

This study demonstrates the possibility of using sanitizing detergents based on natural products for the elimination and/or reduction of Aeromonas hydrophila biofilm formed on stainless steel surfaces. The goal of this work was to determine the reduction effect of sanitizing detergents containing essential oils of Thymus vulgaris (thyme) and Cymbopogon citratus (lemongrass) on biofilm formed by A. hydrophila on AISI 304 stainless steel coupons, using UHT skimmed milk as substratum. There was adhesion and biofilm formation by A. hydrophila at 28 °C, presenting 7.60 log cfu.cm−2 after the fourth day of cultivation. There was no significant difference between the lemongrass treatment and that of the thyme oil (p 0.05). The treatment with lemongrass solution reduced the biofilm by 4.51 log cfu cm−2 at 25 °C. The thyme detergent also reduced the number of cfu cm−2 by 3.84 log cycles at 25 °C. The use of the lemongrass and thyme solutions efficiently reduced the A. hydrophila biofilm. PMID:24159286

The repellency of lemongrass oil against stable flies, tested using video tracking

Science.gov (United States)

Baldacchino, Frédéric; Tramut, Coline; Salem, Ali; Liénard, Emmanuel; Delétré, Emilie; Franc, Michel; Martin, Thibaud; Duvallet, Gérard; Jay-Robert, Pierre

2013-01-01

Lemongrass oil (Cymbopogon citratus) is an effective repellent against mosquitoes (Diptera: Culicidae) and house flies (Diptera: Muscidae). In this study, its effectiveness was assessed on stable flies (Diptera: Muscidae) in laboratory conditions. First, we demonstrated that lemongrass oil is an active substance for antennal olfactory receptor cells of Stomoxys calcitrans as indicated by a significant increase in the electroantennogram responses to increasing doses of lemongrass oil. Feeding-choice tests in a flight cage with stable flies having access to two blood-soaked sanitary pads, one of which was treated with lemongrass oil, showed that stable flies (n = 24) spent significantly more time in the untreated zone (median value = 218.4 s) than in the treated zone (median value = 63.7 s). No stable flies fed on the treated pad, whereas nine fed on the untreated pad. These results suggest that lemongrass oil could be used as an effective repellent against stable flies. Additional studies to confirm its spatial repellent and feeding deterrent effects are warranted. PMID:23759542

Vasorelaxation induced by common edible tropical plant extracts in isolated rat aorta and mesenteric vascular bed.

Science.gov (United States)

Runnie, I; Salleh, M N; Mohamed, S; Head, R J; Abeywardena, M Y

2004-06-01

In this study, the vasodilatory actions of nine edible tropical plant extracts were investigated. Ipomoea batatas (sweet potato leaf), Piper betle (betel leaf), Anacardium occidentale (cashew leaf), Gynandropsis gynandra (maman leaf), Carica papaya (papaya leaf), and Mentha arvensis (mint leaf) extracts exhibited more than 50% relaxing effect on aortic ring preparations, while Piper betle and Cymbopogon citratus (lemongrass stalk) showed comparable vasorelaxation on isolated perfused mesenteric artery preparation. The vascular effect on the aortic ring preparations were mainly endothelium-dependent, and mediated by nitric oxide (NO) as supported by the inhibition of action in the presence of N(omega)-nitro-L-arginine (NOLA), an nitric oxide synthase (NOS) inhibitor, or by the removal of endothelium. In contrast, vasodilatory actions in resistance vessels (perfused mesenteric vascular beds) appear to involve several biochemical mediators, including NO, prostanoids, and endothelium-dependent hyperpolarizing factors (EDHFs). Total phenolic contents and antioxidant capacities varied among different extracts and found to be independent of vascular relaxation effects. This study demonstrates that many edible plants common in Asian diets to possess potential health benefits, affording protection at the vascular endothelium level.

Evaluation of In Vitro Activity of Essential Oils against Trypanosoma brucei brucei and Trypanosoma evansi

Directory of Open Access Journals (Sweden)

Nathan Habila

2010-01-01

Full Text Available Essential oils (EOs from Cymbopogon citratus (CC, Eucalyptus citriodora (EC, Eucalyptus camaldulensis (ED, and Citrus sinensis (CS were obtained by hydrodistillation process. The EOs were evaluated in vitro for activity against Trypanosoma brucei brucei (Tbb and Trypanosoma evansi (T. evansi. The EOs were found to possess antitrypanosomal activity in vitro in a dose-dependent pattern in a short period of time. The drop in number of parasite over time was achieved doses of 0.4 g/ml, 0.2 g/mL, and 0.1 g/mL for all the EOs. The concentration of 0.4 g/mL CC was more potent at 3 minutes and 2 minutes for Tbb and T. evansi, respectively. The GC-MS analysis of the EOs revealed presence of Cyclobutane (96.09% in CS, 6-octenal (77.11% in EC, Eucalyptol (75% in ED, and Citral (38.32% in CC among several other organic compounds. The results are discussed in relation to trypanosome chemotherapy.

Reduction of Aeromonas hidrophyla biofilm on stainless stell surface by essential oils

Directory of Open Access Journals (Sweden)

Alessandra Farias Millezi

2013-01-01

Full Text Available This study demonstrates the possibility of using sanitizing detergents based on natural products for the elimination and/or reduction of Aeromonas hydrophila biofilm formed on stainless steel surfaces. The goal of this work was to determine the reduction effect of sanitizing detergents containing essential oils of Thymus vulgaris (thyme and Cymbopogon citratus (lemongrass on biofilm formed by A. hydrophila on AISI 304 stainless steel coupons, using UHT skimmed milk as substratum. There was adhesion and biofilm formation by A. hydrophila at 28 ºC, presenting 7.60 log cfu.cm-2 after the fourth day of cultivation. There was no significant difference between the lemongrass treatment and that of the thyme oil (p 0.05. The treatment with lemongrass solution reduced the biofilm by 4.51 log cfu cm-2 at 25 ºC. The thyme detergent also reduced the number of cfu cm-2 by 3.84 log cycles at 25 ºC. The use of the lemongrass and thyme solutions efficiently reduced the A. hydrophila biofilm.

Ethnobotanical survey of the medicinal flora used by the Caribs of Guatemala.

Science.gov (United States)

Girón, L M; Freire, V; Alonzo, A; Cáceres, A

1991-09-01

An ethnobotanical survey was conducted among the Carib population of Guatemala in 1988-1989. In general terms, the sample surveyed possessed a relatively good standard of living. Results indicated that health services were utilized by the population, and that domestic medicine, mainly plants (96.9%) was used by 15% of the population. One hundred and nineteen plants used for medicinal purposes were collected, of which 102 (85.7%) could be identified; a list of these together with the information provided for each plant is presented. The most frequently reported plants used as medicine are: Acalypha arvensis, Cassia alata, Cymbopogon citratus, Melampodium divaricatum. Momordica charantia, Neurolaena lobata, Ocimum basilicum, Petiveria alliacea and Solanum nigrescens. Most of these plants are found in the region, but some are brought from the Highlands or outside of the country, such as Malva parviflora, Matricaria chamomilla, Peumus boldus, Pimpinella anisum, Rosmarinus officinalis and Tagetes lucida. This survey demonstrated that the Carib population of Guatemala has survived in a transcultural environment of African and native Amerindian beliefs.

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.

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....

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,

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...

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....

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...

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.

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...

Light weight, high power, high voltage dc/dc converter technologies

Science.gov (United States)

Kraus, Robert; Myers, Ira; Baumann, Eric

1990-01-01

Power-conditioning weight reductions by orders of magnitude will be required to enable the megawatt-power-level space systems envisioned by the Strategic Defense Initiative, the Air Force, and NASA. An interagency program has been initiated to develop an 0.1-kg/kW dc/dc converter technology base for these future space applications. Three contractors are in the first phase of a competitive program to develop a megawatt dc/dc converter. Researchers at NASA Lewis Research Center are investigating innovative converter topology control. Three different converter subsystems based on square wave, resonant, and super-resonant topologies are being designed. The components required for the converter designs cover a wide array of technologies. Two different switches, one semiconductor and the other gas, are under development. Issues related to thermal management and material reliability for inductors, transformers, and capacitors are being investigated in order to maximize power density. A brief description of each of the concepts proposed to meet the goals of this program is presented.

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.

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...

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...

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

Evaluation of irradiated essential oils to control of Sitophilus zeamais Mots. (Coleoptera: Curculionidae) and Blatella germanica (L.) (Dictyopera: Blattellidae); Avaliacao de produtos naturais irradiados para o controle de Sitophilus zeamais Mots. (Coleoptera: Curculionidae) e Blatella germanica (L.) (Dictyopera: Blattellidae)

Energy Technology Data Exchange (ETDEWEB)

Potenza, Marcos Roberto

2004-07-01

This work aimed to evaluate the effect of irradiated essential oils of Eucalyptus citriodora, Eucalyptus globulus, Pinus sp., Azadirachta indica, Cymbopogon nardus, Cupressus sempervirens, Cymbopogons citratus and Juniperus communis and aqueous, hexanic and ethanolic irradiated extracts of Solanum paniculatum, Dahlia pinnata, Lycopersicon esculentum, Nephrolepis pectinata, Ruta graveolens, Ficus elastica, Lavandula angustifolia, Rhododendron simsii, Agave angustifolia, Ocimum basilicum, Allamanda cathartica, Dieffenbachia brasiliensis, Pennisetum purpureum, Annona squamosa, Coffea arabica and Hibiscus rosa-sinensis, in order to identify new substances to integrated pest management (IPM) and to observe possible effects of gamma radiation about extracts and essential oils efficiency such as increase, reduction, activation and inactivation of the same to the pest control. It evaluated the effect of contact on Sitophilus zeamais and by ingestion in Blattella germanica. To irradiation was used an experimental irradiator of Cobalt-60, type Gammacell 220. The essential oils were submitted increasing doses of gamma radiation: 2.5; 5.0; 7.5 and 10.0 kGy. The bioassay with B. germanica demonstrated efficiency between 22.0 e 30.0% and between 30.0 and 42.0%, respectively, to irradiated essential oils of E. citriodora and E. globulus and they demonstrated too repellency to the nymphs. The gamma radiation used promoted changes in essential oils of E. citriodora e E. globulus that they began to show efficiency on B. germanica nymphs besides a significant reduction of repellency. Essential oils of Pinus sp., A. indica, C. sempervirens and J. communis did not display efficiency. The essential oils of C. nardus, and C. citratus had low efficiency. The gamma radiation increased the efficiency of ethanolic extract of D. Pinnata with dose of 7.5 kGy, showing 48.0% of efficiency on B. germanica nymphs. The gamma radiation showed adverse effect on the aqueous extract of R. Graveolens

Evaluation of irradiated essential oils to control of Sitophilus zeamais Mots. (Coleoptera: Curculionidae) and Blatella germanica (L.) (Dictyopera: Blattellidae); Avaliacao de produtos naturais irradiados para o controle de Sitophilus zeamais Mots. (Coleoptera: Curculionidae) e Blatella germanica (L.) (Dictyopera: Blattellidae)

Energy Technology Data Exchange (ETDEWEB)

Potenza, Marcos Roberto

2004-07-01

This work aimed to evaluate the effect of irradiated essential oils of Eucalyptus citriodora, Eucalyptus globulus, Pinus sp., Azadirachta indica, Cymbopogon nardus, Cupressus sempervirens, Cymbopogons citratus and Juniperus communis and aqueous, hexanic and ethanolic irradiated extracts of Solanum paniculatum, Dahlia pinnata, Lycopersicon esculentum, Nephrolepis pectinata, Ruta graveolens, Ficus elastica, Lavandula angustifolia, Rhododendron simsii, Agave angustifolia, Ocimum basilicum, Allamanda cathartica, Dieffenbachia brasiliensis, Pennisetum purpureum, Annona squamosa, Coffea arabica and Hibiscus rosa-sinensis, in order to identify new substances to integrated pest management (IPM) and to observe possible effects of gamma radiation about extracts and essential oils efficiency such as increase, reduction, activation and inactivation of the same to the pest control. It evaluated the effect of contact on Sitophilus zeamais and by ingestion in Blattella germanica. To irradiation was used an experimental irradiator of Cobalt-60, type Gammacell 220. The essential oils were submitted increasing doses of gamma radiation: 2.5; 5.0; 7.5 and 10.0 kGy. The bioassay with B. germanica demonstrated efficiency between 22.0 e 30.0% and between 30.0 and 42.0%, respectively, to irradiated essential oils of E. citriodora and E. globulus and they demonstrated too repellency to the nymphs. The gamma radiation used promoted changes in essential oils of E. citriodora e E. globulus that they began to show efficiency on B. germanica nymphs besides a significant reduction of repellency. Essential oils of Pinus sp., A. indica, C. sempervirens and J. communis did not display efficiency. The essential oils of C. nardus, and C. citratus had low efficiency. The gamma radiation increased the efficiency of ethanolic extract of D. Pinnata with dose of 7.5 kGy, showing 48.0% of efficiency on B. germanica nymphs. The gamma radiation showed adverse effect on the aqueous extract of R. Graveolens

Evaluation of irradiated essential oils to control of Sitophilus zeamais Mots. (Coleoptera: Curculionidae) and Blatella germanica (L.) (Dictyopera: Blattellidae)

International Nuclear Information System (INIS)

Potenza, Marcos Roberto

2004-01-01

This work aimed to evaluate the effect of irradiated essential oils of Eucalyptus citriodora, Eucalyptus globulus, Pinus sp., Azadirachta indica, Cymbopogon nardus, Cupressus sempervirens, Cymbopogons citratus and Juniperus communis and aqueous, hexanic and ethanolic irradiated extracts of Solanum paniculatum, Dahlia pinnata, Lycopersicon esculentum, Nephrolepis pectinata, Ruta graveolens, Ficus elastica, Lavandula angustifolia, Rhododendron simsii, Agave angustifolia, Ocimum basilicum, Allamanda cathartica, Dieffenbachia brasiliensis, Pennisetum purpureum, Annona squamosa, Coffea arabica and Hibiscus rosa-sinensis, in order to identify new substances to integrated pest management (IPM) and to observe possible effects of gamma radiation about extracts and essential oils efficiency such as increase, reduction, activation and inactivation of the same to the pest control. It evaluated the effect of contact on Sitophilus zeamais and by ingestion in Blattella germanica. To irradiation was used an experimental irradiator of Cobalt-60, type Gammacell 220. The essential oils were submitted increasing doses of gamma radiation: 2.5; 5.0; 7.5 and 10.0 kGy. The bioassay with B. germanica demonstrated efficiency between 22.0 e 30.0% and between 30.0 and 42.0%, respectively, to irradiated essential oils of E. citriodora and E. globulus and they demonstrated too repellency to the nymphs. The gamma radiation used promoted changes in essential oils of E. citriodora e E. globulus that they began to show efficiency on B. germanica nymphs besides a significant reduction of repellency. Essential oils of Pinus sp., A. indica, C. sempervirens and J. communis did not display efficiency. The essential oils of C. nardus, and C. citratus had low efficiency. The gamma radiation increased the efficiency of ethanolic extract of D. Pinnata with dose of 7.5 kGy, showing 48.0% of efficiency on B. germanica nymphs. The gamma radiation showed adverse effect on the aqueous extract of R. Graveolens

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.

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...

PERBANDINGAN APLIKASI EKSTRAK SEREH DAPUR DAN ESTRAK SEREH WANGI TERHADAP RADANG MUKOSA MULUT (Penelitian Laboratorik pada Tikus Wistar Strain LMR

Directory of Open Access Journals (Sweden)

Mindya Juniastuti

2015-07-01

Full Text Available Inflammation is one of the body's defence mechanism against irritants, infectious agents, and injury. During its process, pain, swelling, redness, and other discomforts also occur as cardinal signs of inflammation. Therefore, people seek for medicine to encounter those effects. Sereh is one of the herb plants which have anti inflammatory effect. However, effect of Sereh on inglamed oral mucosa has not been clinically examined. The aim of this research is to examine and to compare the influence of Sered Dapur (Cymbopogon citratus and Sereh Wangi (Cymbopogon winterianus lowitt extract on inflamed oral mucous induced by Hydrogen Peroxide 10%. Thirteen Wistar rats were used in this research and divided four groups, control group I (3 rats, control group II (3 rats, Sereh Dapur extract groups (4 rats and Sereh Wangi extract groups (3 rats. All rats in Sereh Dapur, Sereh Wangi and control II groups received 3x10 minutes application of Hydrogen Peroxide 10% on their vestibulum for 3 days, while rats in control gorup I received application of Aquadest. On the 4th day, all groups that received Hydrogen Peroxide 10% were application 3x5 minutes for 3 days for each substance. After rats have been killed their oral mucosa were processed and examine under microscope. Statistical result shows there are differences on oral mucous reaction between Sereh Dapur and Sereh Wangi extract with control group. Based on the research result, it can be concluded that both Sereh Dapur and Sereh Wangi can reduce oral mucous inlammation and Sereh Dapur is more effective than Sereh Wangi in reducing the oral mucous inflammation induced by Hydrogen Peroxide 10%.

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.

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...

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.

DC Rocks! Using Place-Based Learning to Introduce Washington DC's K-12 Students to the Geosciences

Science.gov (United States)

Mayberry, G. C.; Mattietti, G. K.

2017-12-01

The Washington DC area has interesting geology and a multitude of agencies that deal with the geosciences, yet K-12 public school students in DC, most of whom are minorities, have limited exposure to the geosciences. Geoscience agencies in the DC area have a unique opportunity to address this by introducing the geosciences to local students who otherwise may not have such an opportunity, by highlighting the geology in the students' "backyard," and by leveraging partnerships among DC-based geoscience-related agencies. The USGS and George Mason University are developing a project called DC Rocks, which will give DC's students an exciting introduction into the world of geoscience with place-based learning opportunities that will make geoscience relevant to their lives and their futures. Both the need in DC and the potential for lasting impact are great; the geosciences have the lowest racial diversity of all the science, technology, engineering, and math (STEM) fields, 89% of students in DC public schools are minorities, and there is no dedicated geoscience curriculum in DC. DC Rocks aims to give these students early exposure to the earth sciences, and encourage them to consider careers in the profession. DC Rocks will work with partner agencies to apply several methods that are recommended by researchers to increase the participation of minority students in the geosciences, including providing profoundly positive experiences that spark interest in the geosciences (Levine et al., 2007); increasing students' sense of belonging in the geosciences (Huntoon, et al, 2016); and place-based teaching practices that emphasize the study of local sites (Semken, 2005), such as DC's Rock Creek Park. DC Rocks will apply these methods by coordinating local geoscientists and resources to provide real-world examples of the geosciences' impact on students' lives. Through the DC Rocks website, educators will be able to request geoscience-related resources such as class presentations by

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.

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.

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.

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...

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.

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.

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.

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.

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.

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...

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...

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).

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.

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.

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...

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.

Impact of DC link control strategies on the power-flow convergence of integrated AC–DC systems

Directory of Open Access Journals (Sweden)

Shagufta Khan

2016-03-01

Full Text Available For the power-flow solution of integrated AC–DC systems, five quantities are required to be solved per converter, against three independent equations available. These three equations consist of two basic converter equations and one DC network equation, corresponding to each converter. Thus, for solution, two additional equations are required. These two equations are derived from the control specifications adopted for the DC link. Depending on the application, several combinations of valid control specifications are possible. A set of valid control specifications constitutes a control strategy. It is observed that the control strategy adopted for the DC link strongly affects the power-flow convergence of integrated AC–DC systems. This paper investigates how different control strategies affect the power flow convergence of integrated AC–DC systems. Sequential method is used to solve the DC variables in the Newton Raphson (NR power flow model. Seven typical control strategies have been taken into consideration. This is validated by numerous case studies carried out with multiple DC links incorporated in the IEEE 118-bus and 300-bus test systems.

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...

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)

75 FR 47199 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-9-10 Series Airplanes, DC-9-30...

Science.gov (United States)

2010-08-05

... Airworthiness Directives; McDonnell Douglas Corporation Model DC- 9-10 Series Airplanes, DC-9-30 Series... existing airworthiness directive (AD), which applies to all McDonnell Douglas Model DC-9-10 series..., 2010). That AD applies to all McDonnell Douglas Corporation Model DC-9-10 series airplanes, DC-9-30...

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 ...

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

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.

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....

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....

Open- and Short-Circuit Fault Identification for a Boost dc/dc Converter in PV MPPT Systems

Directory of Open Access Journals (Sweden)

Diego R. Espinoza Trejo

2018-03-01

Full Text Available This paper proposes a fault identification system for short and open-circuit switch faults (SOCSF for a dc/dc converter acting as a Maximum Power Point Tracker (MPPT in Photovoltaic (PV systems. A closed-loop operation is assumed for the boost dc/dc converter. A linearizing control plus a Proportional-Derivative (PD controller is suggested for PV voltage regulation at the maximum power point (MPP. In this study, the SOCSF are modeled by using an additive fault representation and the fault identification (FI system is synthesized departing from a Luenberger observer. Hence, an FI signal is obtained, which is insensitive to irradiance and load current changes, but affected by the SOCSF. For FI purposes, only the sensors used in the control system are needed. Finally, an experimental evaluation is presented by using a solar array simulator dc power supply and a boost dc/dc converter of 175 W in order to validate the ideas this study exposes.

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...

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%

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%.

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.

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

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

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.

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.

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

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)

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...

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...

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

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.

Efficient Visible Light Communication Transmitters Based on Switching-Mode dc-dc Converters

Science.gov (United States)

2018-01-01

Visible light communication (VLC) based on solid-state lighting (SSL) is a promising option either to supplement or to substitute existing radio frequency (RF) wireless communication in indoor environments. VLC systems take advantage of the fast modulation of the visible light that light emitting diodes (LEDs) enable. The switching-mode dc-to-dc converter (SMCdc-dc) must be the cornerstone of the LED driver of VLC transmitters in order to incorporate the communication functionality into LED lighting, keeping high power efficiency. However, the new requirements related to the communication, especially the high bandwidth that the LED driver must achieve, converts the design of the SMCdc-dc into a very challenging task. In this work, three different methods for achieving such a high bandwidth with an SMCdc-dc are presented: increasing the order of the SMCdc-dc output filter, increasing the number of voltage inputs, and increasing the number of phases. These three strategies are combinable and the optimum design depends on the particular VLC application, which determines the requirements of the VLC transmitter. As an example, an experimental VLC transmitter based on a two-phase buck converter with a fourth-order output filter will demonstrate that a bandwidth of several hundred kilohertz (kHz) can be achieved with output power levels close to 10 W and power efficiencies between 85% and 90%. In conclusion, the design strategy presented allows us to incorporate VLC into SSL, achieving high bit rates without damaging the power efficiency of LED lighting. PMID:29642455

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.

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...

AC Voltage Control of DC/DC Converters Based on Modular Multilevel Converters in Multi-Terminal High-Voltage Direct Current Transmission Systems

Directory of Open Access Journals (Sweden)

Rui Li

2016-12-01

Full Text Available The AC voltage control of a DC/DC converter based on the modular multilevel converter (MMC is considered under normal operation and during a local DC fault. By actively setting the AC voltage according to the two DC voltages of the DC/DC converter, the modulation index can be near unity, and the DC voltage is effectively utilized to output higher AC voltage. This significantly decreases submodule (SM capacitance and conduction losses of the DC/DC converter, yielding reduced capital cost, volume, and higher efficiency. Additionally, the AC voltage is limited in the controllable range of both the MMCs in the DC/DC converter; thus, over-modulation and uncontrolled currents are actively avoided. The AC voltage control of the DC/DC converter during local DC faults, i.e., standby operation, is also proposed, where only the MMC connected on the faulty cable is blocked, while the other MMC remains operational with zero AC voltage output. Thus, the capacitor voltages can be regulated at the rated value and the decrease of the SM capacitor voltages after the blocking of the DC/DC converter is avoided. Moreover, the fault can still be isolated as quickly as the conventional approach, where both MMCs are blocked and the DC/DC converter is not exposed to the risk of overcurrent. The proposed AC voltage control strategy is assessed in a three-terminal high-voltage direct current (HVDC system incorporating a DC/DC converter, and the simulation results confirm its feasibility.

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.

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)

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.

On-grid and Off-grid Operation of Multi-Input Single-Output DC/DC Converter based Fuel Cell Generation System

Directory of Open Access Journals (Sweden)

Noroozian

2009-06-01

Full Text Available This paper presents the modeling and simulation of a proton exchange membrane fuel cell (PEMFC generation system for off-grid and on-grid operation and configuration. A fuel cell DG system consists of a fuel cell power plant, a DC/DC converter and a DC/AC inverter. The dynamic model for fuel cell array and its power electronic interfacing are presented also a multi-input single output (MISO DC/DC converter and its control scheme is proposed and analyzed. This DC/DC converter is capable of interfacing fuel cell arrays to the DC/AC inverter. Also the mathematical model of the inverter is obtained by using average technique. Then the novel control strategy of DC/AC inverter for different operating conditions is demonstrated. The simulation results show the effectiveness of the suggested control systems under both on-grid and off-grid operation modes.

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

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.

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.

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...

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...

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.

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.

Modelling and Control Design of a Dual Buck-Boost AC/DC Converter Used in the DC Nano-Grid

DEFF Research Database (Denmark)

Wu, Weimin; Liu, Yuan; Wang, Houqing

2016-01-01

Due to widely used DC characterized loads and more distributed power generation sources, the DC Nano-grid becomes more and more popular and seen as an alternative to the AC-grid in future. For the safety considerations, the DC Nano-grid should provide reliable grounding for the residential loads...... like the low voltage AC power system. In this paper, a dual Buck-Boost AC/DC converter for use in the united grounding configuration based DC Nano-grid with three terminal outputs is proposed. It will be much easy to construct an efficient DC Nano-grid based on the existing low AC power system by using...

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...

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

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.

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...

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...

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...

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...

Integrating DC/DC Conversion with Possible Reconfiguration within Submodule Solar Photovoltaic Systems

Science.gov (United States)

Huang, Peter Jen-Hung

This research first proposes a method to merge photovoltaic (PV) cells or PV panels within the internal components DC-DC converters. The purpose of this merged structure is to reconfigure the PV modules between series and parallel connections using high switching frequencies (hundreds of kHz). This leads to multi-levels of voltages and currents that become applied to the output filter of the converter. Further, this research introduces a concept of a switching cell that utilizes the reconfiguration of series and parallel connections in DC-DC converters. The switching occurs at high switching frequency and the switches can be integrated to be within the solar panels or in between the solar cells. The concept is generalized and applied to basic buck and boost topologies. As examples of the new types of converters: reconfigurable PV-buck and PV-boost converter topologies are presented. It is also possible to create other reconfigurable power converters: non-isolated and isolated topologies. Analysis, simulation and experimental verification for the reconfigurable PV-buck and PV-boost converters are presented extensively to illustrate proof of concept. Benefits and drawbacks of the new approach are discussed. The second part of this research proposes to utilize the internal solar cell capacitance and internal solar module wire parasitic inductances to replace the input capacitor and filter inductor in boost derived DC-DC converters for energy harvesting applications. High switching frequency (MHz) hard switched and resonant boost converters are proposed. Their analysis, simulation and experimental prototypes are presented. A specific proof-of-concept application is especially tested for foldable PV panels, which are known for their high internal wire inductance. The experimental converters successfully boost solar module voltage without adding any external input capacitance or filter inductor. Benefits and drawbacks of new proposed PV submodule integrated boost

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)

Retrospective evaluation of early and aggressive decompressive craniectomy (DC) for severe head injury. Was that DC necessary?

International Nuclear Information System (INIS)

Hagihara, Yasushi; Ueno, Masato; Mizushima, Yasuaki; Matsuoka, Tetsuya

2011-01-01

Recently, decompressive craniectomy (DC) for refractory intracranial hypertension (IH) has been widely reevaluated, and many researchers support the advantages of early and aggressive DC in the management of severe head trauma. We too applied DC in the early stages of IH, and confirmed its favorable results compared to those of the standard treatment. In patients with evacuate masses (EM), DC was determined based on the intraoperative condition of the brain parenchyma; in those without EM, intracranial pressure (ICP) ≥30 mmHg was considered the criterion for DC. However, in some cases, the expected brain edema (BE) was absent after DC, and DC seemed unnecessary on retrospection. Here, the effectiveness of DC performed at our hospital and its predictive factors were investigated. Of the 26 DCs performed in the past 3.5 years, 9 were ineffective because the expected BEs were absent on postoperative computed tomography. In those 9 cases, the Glasgow coma scale (GCS) scores and D-dimer of fibrinogen degradation product (FDP-DD) were significantly higher and lower, respectively, than those of the control group. Patients with EM showed similar trends regarding the GCS score and FDP-DD, both of which are probable indicators of BE. In patients without EM, the GCS score and FDP-DD were normal, but their base excess at admission was significantly low with increased ICP, requiring DC. GCS score and FDP-DD may represent the extent of mechanically damaged brain, and this may explain their relation with DC effectiveness in patients with EM. In patients without EM and with mild brain damage, base excess that reflects the respiratory or circulatory disorder should be the predictor for BE. (author)

Exploration of Charge Recycling DC-DC Conversion Using a Switched Capacitor Regulator

Directory of Open Access Journals (Sweden)

Mircea R. Stan

2013-07-01

Full Text Available The increasing popularity of DVFS (dynamic voltage frequency scaling schemes for portable low power applications demands highly efficient on-chip DC-DC converters. The primary aim of this work is to enable increased efficiency of on-chip DC-DC conversion for near-threshold operation of multicore chips. The idea is to supply nominal (high off-chip voltage to the cores which are then “voltage-stacked” to generate the near-threshold (low voltages based on Kirchhoff’s voltage law through charge recycling. However, the effectiveness of this implicit down-conversion is affected by the current imbalance among the cores. The paper presents a design methodology and optimization strategy for highly efficient charge recycling on-chip regulation using a push-pull switched capacitor (SC circuit. A dual-boundary hysteretic feedback control circuit has been designed for stacked loads. A stacked-voltage domain with its self-regulation capability combined with a SC converter has shown average efficiency of 78%–93% for 2:1 down-conversion with ILoad (max of 200 mA and workload imbalance varying from 0–100%.

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...

High-Efficiency High Step-Up DC-DC Converter with Dual Coupled Inductors for Grid-Connected Photovoltaic Systems

DEFF Research Database (Denmark)

Forouzesh, Mojtaba; Shen, Yanfeng; Siwakoti, Yam Prasad

2018-01-01

with a common ground connection of the input and output make the proposed topology a proper candidate for a transformer-less grid connected photovoltaic systems. The operating performance, analysis and mathematical derivations of the proposed dc-dc converter have been demonstrated in the paper. Moreover......This paper introduces a non-isolated high step-up dc-dc converter with dual coupled inductors suitable for distributed generation applications. By implementing an input parallel connection, the proposed dc-dc structure inherits shared input current with low ripple, which also requires small...... capacitive filter at its input. Moreover, this topology can reach high voltage gain by using dual coupled inductors in series connection at the output stage. The proposed converter uses active clamp circuits with a shared clamp capacitor for the main switches. In addition to the active clamp circuit...

Design and Implementation of Anti-windup PI Control on DC-DC Bidirectional Converter for Hybrid Vehicle Applications

Directory of Open Access Journals (Sweden)

Muh. Zakiyullah Romdlony

2012-07-01

Full Text Available Well-regulated DC bus voltage is the important point to guarantee the power demand in hybrid vehicle applications. Voltage regulation can be achieved with control method that build switching signal on DC-DC converter. This paper describes design and small scale experimental results of bus voltage regulation control of the DC-DC bidirectional converter with battery and supercapacitor as energy source. The control system consists of two control loops, the outer loop that get DC bus voltage feedback using PI anti-windup back calculation control method. This outer loop will generate a reference current for the inner loop that implement hysteresis control. The inner control loop will compare that reference curent with the source current obtained from the current sensor. Simulation and experimental results show that bus voltage is well-regulated under the load changes with 1% voltage ripple.

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.

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...

Atividade antibacteriana de óleos essenciais em cepas isoladas de infecção urinária Antibacterial activity of essential oils on microorganisms isolated from urinary tract infection

Directory of Open Access Journals (Sweden)

Rogério Santos Pereira

2004-04-01

Full Text Available A análise da atividade antibacteriana de óleos essenciais de ervas medicinais (Ocimum gratissimum, L., Cybopogum citratus (DC Stapf. e Salvia officinalis, L. foi verificada frente a 100 cepas de bactérias isoladas de indivíduos da comunidade com diagnóstico de infecção urinária. Os microrganismos foram semeados em ágar Muller Hinton e os extratos aplicados com replicador de Steers e incubados a 37°C por 24 horas. Verificou-se que Salvia officinalis, L. apresentou ação inibitória superior às outras ervas, tendo eficácia de 100% quando testadas em espécies de Klebsiella e Enterobacter, 96% em Escherichia coli, 83% contra Proteus mirabilis e 75% contra Morganella morganii.The antibacterial activity of essential oils extracted from medicinal plants (Ocimum gratissimum, L., Cybopogum citratus (DC Stapf., and Salvia officinalis, L. was assessed on bacterial strains derived from 100 urine samples. Samples were taken from subjects diagnosed with urinary tract infection living in the community. Microorganisms were plated on Müller Hinton agar. Plant extracts were applied using a Steers replicator and petri dishes were incubated at 37°C for 24 hours. Salvia officinalis, L. showed enhanced inhibitory activity compared to the other two herbs, with 100% efficiency against Klebsiella and Enterobacter species, 96% against Escherichia coli, 83% against Proteus mirabilis, and 75% against Morganella morganii.

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

UNJUK KERJA PENGUBAH TEGANGAN DC-DC TOPOLOGI BOOST DENGAN NILAI INDUKTANSI DAN KAPASITANSI YANG DIOPTIMASI PADA KEADAAN TRANSIEN

Directory of Open Access Journals (Sweden)

I Wayan Arta Wijaya

2009-05-01

Full Text Available Pengubah daya DC-DC topologi boost dapat menghasilkan tegangan yang lebih tinggi dari tegangan input dengan riak (ripple yang kecil dan efisiensi yang cukup tinggi. Nilai dari sebuah induktansi dan kapasitansi dari pengubah daya DC-DC dengan menggunakan topologi boost dioptimalkan menggunakan analisa transien. Fungsi ini diatur berdasarkan pada analisa dari pengubah daya selama kondisi transien. Nilai induktansi dan kapasitansi yang telah dioptimalkan dengan perhitungan dibandingkan dalam simulasi pada pengubah daya DC-DC dan hasilnya akan dibuktikan dengan menggunakan hasil percobaan. Nilai optimal untuk kapasitor dan induktor pada frekuensi 666,7 Hz, siklus kerja (duty cycle 66,7 %, resistansi output 36 Ώ dan tegangan input 12 volt adalah 1038 μF dan 11,9 mH

Rhesus macaque and chimpanzee DC-SIGN act as HIV/SIV gp120 trans-receptors, similar to human DC-SIGN

NARCIS (Netherlands)

Geijtenbeek, T. B.; Koopman, G.; van Duijnhoven, G. C.; van Vliet, S. J.; van Schijndel, A. C.; Engering, A.; Heeney, J. L.; van Kooyk, Y.

2001-01-01

Dendritic cells (DC) have been implicated in the pathogenesis of both human and simian immunodeficiency viruses (HIV and SIV, respectively). The DC-specific HIV-1 trans-receptor DC-SIGN is thought to be essential for viral dissemination by DC. Abundant expression in lymphoid tissues also implies a

The Chaotic-Based Control of Three-Port Isolated Bidirectional DC/DC Converters for Electric and Hybrid Vehicles

Directory of Open Access Journals (Sweden)

Zheng Wang

2016-01-01

Full Text Available Three-port isolated (TPI bidirectional DC/DC converters have three energy ports and offer advantages of large voltage gain, galvanic isolation ability and high power density. For this reason this kind of converters are suitable to connect different energy sources and loads in electric and hybrid vehicles. The purpose of this paper is to propose chaotic modulation and the related control scheme for TPI bidirectional DC/DC converters, in such a way that the switching harmonic peaks can be suppressed in spectrum and the conducted electromagnetic interference (EMI is reduced. Two chaotic modulation strategies, namely the continuously chaotic modulation and the discretely chaotic modulation are presented. These two chaotic modulation strategies are applied for TPI bidirectional DC/DC converters with shifted-phase angle based control and phase-shifted PWM control. Both simulation and experiments are given to verify the validity of the proposed chaotic modulation-based control schemes.

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.

A Markovian Approach Applied to Reliability Modeling of Bidirectional DC-DC Converters Used in PHEVs and Smart Grids

Directory of Open Access Journals (Sweden)

M. Khalilzadeh

2016-12-01

Full Text Available In this paper, a stochastic approach is proposed for reliability assessment of bidirectional DC-DC converters, including the fault-tolerant ones. This type of converters can be used in a smart DC grid, feeding DC loads such as home appliances and plug-in hybrid electric vehicles (PHEVs. The reliability of bidirectional DC-DC converters is of such an importance, due to the key role of the expected increasingly utilization of DC grids in modern Smart Grid. Markov processes are suggested for reliability modeling and consequently calculating the expected effective lifetime of bidirectional converters. A three-leg bidirectional interleaved converter using data of Toyota Prius 2012 hybrid electric vehicle is used as a case study. Besides, the influence of environment and ambient temperature on converter lifetime is studied. The impact of modeling the reliability of the converter and adding reliability constraints on the technical design procedure of the converter is also investigated. In order to investigate the effect of leg increase on the lifetime of the converter, single leg to five-leg interleave DC-DC converters are studied considering economical aspect and the results are extrapolated for six and seven-leg converters. The proposed method could be generalized so that the number of legs and input and output capacitors could be an arbitrary number.

Microbial load and stability of some phyto chemical compounds of selected Sudanese medicinal plant materials as affected by gamma irradiation

International Nuclear Information System (INIS)

Musa, H. A. A.; Ahmed, E. E. A.; Osman, G. A. M.; Ali, H. A.; Muller, J. L.

2011-01-01

The aim of the present study was to evaluate the effect of gamma irradiation treatment on seeds of pepper cress (lepidium sativum L), seeds of black mustard (brassica nigra L.Koch), leaves of lemon grass (cymbopogon citratus), and calyces of roselle (hibiscus sabdariffa L), pods of senna (cassia senna L) and pods prickly acacia (Acacia nilotica L.). The radiation processing was carried out at dose levels of 0, 5, 10. 15 kGy. The irradiated and control samples were analyzed for microbial load, tannins and total phenol content as well as DPPH scavenging activity. The results indicated that gamma radiation treatment significantly reduced microbial load and showed that the total microbial load decreased linearly with absorbed radiation dose. They, also, indicated maximum reduction in tannin content in lemon grass, prickly acacia and roselle. On the other hand, irradiation with 15 kGy increased the tannin and phenol contents in black mustard, pepper cress and senna and reduced the phenol content of roselle and prickly acacia. The results also revealed that gamma irradiation resulted in significant decrease of DPPH radical scavenging activity of the different studied methanolic extracts with exception of pepper cress seeds.(Author)

Bioactivities of Traditional Medicinal Plants in Alexandria.

Science.gov (United States)

Elansary, Hosam O; Szopa, Agnieszka; Kubica, Paweł; Ekiert, Halina; Ali, Hayssam M; Elshikh, Mohamed S; Abdel-Salam, Eslam M; El-Esawi, Mohamed; El-Ansary, Diaa O

2018-01-01

In traditional folklore, medicinal herbs play a vital role in the prevention and treatment of microbial diseases. In the present study, the phenolic profiles of the medicinal plants Asparagus aethiopicus L., Citrullus colocynthis L., Senna alexandrina L., Kalanchoe delagoensis L., Gasteria pillansii L., Cymbopogon citratus , Brassica juncea , and Curcuma longa L. were determined by high-performance liquid chromatography with a diode-array detector method. The results revealed rich sources of important compounds such as robinin in the fruits and leaves of A. aethiopicus ; caffeic acid in the tubers of A. aethiopicus and quercitrin in the leaves of G. pillansii . Further, relatively high antioxidant, antibacterial, and antifungal activities were observed in C. colocynthis fruit coat, S. alexandrina pods, and A. aethiopicus leaves, respectively. The relatively higher the bioactivities of plants extracts associated with the phenols in these plants, in particular, the more abundant the phenols. Therefore, it was concluded that the fruit coat of C. colocynthis , pods of S. alexandrina , and leaves of A. aethiopicus might be excellent sources of natural products. These plant extracts also have a wide spectrum of antimicrobial activities that could be used in the pharmaceutical industries and to control diseases.

Bioactivities of Traditional Medicinal Plants in Alexandria

Directory of Open Access Journals (Sweden)

Hosam O. Elansary

2018-01-01

Full Text Available In traditional folklore, medicinal herbs play a vital role in the prevention and treatment of microbial diseases. In the present study, the phenolic profiles of the medicinal plants Asparagus aethiopicus L., Citrullus colocynthis L., Senna alexandrina L., Kalanchoe delagoensis L., Gasteria pillansii L., Cymbopogon citratus, Brassica juncea, and Curcuma longa L. were determined by high-performance liquid chromatography with a diode-array detector method. The results revealed rich sources of important compounds such as robinin in the fruits and leaves of A. aethiopicus; caffeic acid in the tubers of A. aethiopicus and quercitrin in the leaves of G. pillansii. Further, relatively high antioxidant, antibacterial, and antifungal activities were observed in C. colocynthis fruit coat, S. alexandrina pods, and A. aethiopicus leaves, respectively. The relatively higher the bioactivities of plants extracts associated with the phenols in these plants, in particular, the more abundant the phenols. Therefore, it was concluded that the fruit coat of C. colocynthis, pods of S. alexandrina, and leaves of A. aethiopicus might be excellent sources of natural products. These plant extracts also have a wide spectrum of antimicrobial activities that could be used in the pharmaceutical industries and to control diseases.

La biotecnología en el tratamiento de úlcera vascular: estudio de caso

Directory of Open Access Journals (Sweden)

Alana Tamar Oliveira de Sousa

2013-07-01

Full Text Available El objetivo de este estudio de caso fue describir la asistencia prestada a una paciente portadora de úlcera venosa mediante la utlización de asociaciones de solución de limpieza a base de cloruro de sodio y del aceite esencial de las hojas de Cymbopogon citratus Stapf, gel a base de Aloe vera, colágeno y una cobertura de película de hemicelulosa. Se realizó acompañamiento a la paciente durante las curaciones, la evolución de la lesión y la aplicación del tratamiento establecido, a partir de las escalas de valoración se pudieron obtener los datos necesarios para conocer los resultados de la terapéutica utilizada. La asociación de los productos y el seguimiento de las orientaciones sobre los cuidados de la enfermedad de la paciente, evidenciaron resultados positivos en cuanto a la cicatrización, la reducción del dolor y olor. El uso de productos adecuados a las condiciones de la úlcera y las escalas utilizadas para evaluaciones sistemáticas de la herida, mostraron avances en los procesos de cicatrización.

Aktivitas minyak dan serbuk enam spesies tumbuhan terhadap peneluran dan Mortalitas Callosobruchus sp. (Coleoptera: Bruchidae

Directory of Open Access Journals (Sweden)

Dadang Dadang

2017-02-01

Full Text Available Storage pests remain one of the main problems in storage. The pest attacks occur not only in the field, but also in storage. Control should be done to maintain the quality of storedproducts. The environmentally friendly measures should be implemented to avoid negative impacts to the environment and human being. The objective of this research was to study the mortality and oviposition deterrence caused by powder and oil of six plant species against Callosobruchus sp. (Coleoptera: Bruchidae. Flowers of Eugenia aromatica, roots of Vetiveria zizanioides, leaves of Pogostemon cablin, seeds of Ricinus communis, seeds of Foeniculum vulgare, and stems of Cymbopogon citratus were air-dried and milled to yield powder. Oil of six plant species were purchased from local market. Oviposition deterrent bioassay was conducted by no-choice method for both powder and oil, while mortality bioassay was conducted by topical application and residual methods for plant oil only. Several plant species showed high biological activity to Callosobruchus sp. Powder of E. aromatica and oil of V. zizanioides caused high oviposition deterrence, while oil of V. zizanioides and E. aromatica caused high mortality.

Bioactivities of Traditional Medicinal Plants in Alexandria

Science.gov (United States)

Szopa, Agnieszka; Kubica, Paweł; Ekiert, Halina; Elshikh, Mohamed S.; Abdel-Salam, Eslam M.; El-Ansary, Diaa O.

2018-01-01

In traditional folklore, medicinal herbs play a vital role in the prevention and treatment of microbial diseases. In the present study, the phenolic profiles of the medicinal plants Asparagus aethiopicus L., Citrullus colocynthis L., Senna alexandrina L., Kalanchoe delagoensis L., Gasteria pillansii L., Cymbopogon citratus, Brassica juncea, and Curcuma longa L. were determined by high-performance liquid chromatography with a diode-array detector method. The results revealed rich sources of important compounds such as robinin in the fruits and leaves of A. aethiopicus; caffeic acid in the tubers of A. aethiopicus and quercitrin in the leaves of G. pillansii. Further, relatively high antioxidant, antibacterial, and antifungal activities were observed in C. colocynthis fruit coat, S. alexandrina pods, and A. aethiopicus leaves, respectively. The relatively higher the bioactivities of plants extracts associated with the phenols in these plants, in particular, the more abundant the phenols. Therefore, it was concluded that the fruit coat of C. colocynthis, pods of S. alexandrina, and leaves of A. aethiopicus might be excellent sources of natural products. These plant extracts also have a wide spectrum of antimicrobial activities that could be used in the pharmaceutical industries and to control diseases. PMID:29636772

PI and Fuzzy Control Strategies for High Voltage Output DC-DC Boost Power Converter - Hardware Implementation and Analysis

DEFF Research Database (Denmark)

Padmanaban, Sanjeevi Kumar; Blaabjerg, Frede; Siano, Pierluigi

2016-01-01

This paper presents the control strategies by Proportional-Integral (P-I) and Fuzzy Logic (FL) for a DC-DC boost power converter for high output voltage configuration. Standard DC-DC converters are traditionally used for high voltage direct current (HVDC) power transmission systems. But, lack its...... converter with inbuilt voltage-lift technique and overcome the aforementioned deficiencies. Further, the control strategy is adapted based on proportional-integral (P-I) and fuzzy logic, closed-loop controller to regulate the outputs and ensure the performances. Complete hardware prototype of EHV converter...... performances in terms of efficiency, reduced transfer gain and increased cost with sensor units. Moreover, the internal self-parasitic components reduce the output voltage and efficiency of classical high voltage converters (HVC). This investigation focused on extra high-voltage (EHV) DC-DC boost power...

A Novel Quasi-SEPIC High-Voltage Boost DC-DC Converter

DEFF Research Database (Denmark)

Siwakoti, Yam Prasad; N. Soltani, Mohsen; Blaabjerg, Frede

2017-01-01

This paper proposes a modified coupled-inductor SEPIC dc-dc converter for low power and high voltage gain applications such as for piezoelectric drive systems. The converter uses the same components as of SEPIC converter with an additional diode. Compared to conventional topologies with similar...... voltage gain expression, the proposed topology uses less components to achieve same or even higher voltage gain. This helps to design a very compact and light weight converter with higher power density at lower cost. Due to brevity, the principle of operation, theoretical analysis and comparison supported...

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.

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.

The 25 kW resonant dc/dc power converter

Science.gov (United States)

Robson, R. R.

1983-01-01

The feasibility of processing 25-kW of power with a single, transistorized, series resonant converter stage was demonstrated by the successful design, development, fabrication, and testing of such a device which employs four Westinghouse D7ST transistors in a full-bridge configuration and operates from a 250-to-350 Vdc input bus. The unit has an overall worst-case efficiency of 93.5% at its full rated output of 1000 V and 25 A dc. A solid-state dc input circuit breaker and output-transient-current limiters are included in and integrated into the design. Full circuit details of the converter are presented along with the test data.

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.

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)

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.

Static and Dynamic Characteristics of DC-DC Converter Using a Digital Filter

Science.gov (United States)

Kurokawa, Fujio; Okamatsu, Masashi

This paper presents the regulation and dynamic characteristics of the dc-dc converter with digital PID control, the minimum phase FIR filter or the IIR filter, and then the design criterion to improve the dynamic characteristics is discussed. As a result, it is clarified that the DC-DC converter using the IIR filter method has superior performance characteristics. The regulation range is within 1.3%, the undershoot against the step change of the load is less than 2% and the transient time is less than 0.4ms with the IIR filter method. In this case, the switching frequency is 100kHz and the step change of the load R is from 50 Ω to 10 Ω. Further, the superior characteristics are obtained when the first gain, the second gain and the second cut-off frequency are relatively large, and the first cut-off frequency and the passing frequency are relatively low. Moreover, it is important that the gain strongly decreases at the second cut-off frequency because the upper band pass frequency range must be always less than half of the sampling frequency based on the sampling theory.

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