Polyacetylene
Mostrando 1-12 de 12 artigos, teses e dissertações.
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1. Constituintes químicos de Vernonia scorpioides (Lam) Pers. (Asteraceae)
The chemical investigation of hexane and ethanol extracts from the aerial parts of Vernonia scorpioides resulted in the isolation and characterization of a new polyacetylene lactone, rel-4-dihydro-4β-hydroxy-5a-octa-2,4,6-triynyl-furan-2-(5H)-one, along with the new ethyl 3,4-dihydroxy-6,8,10-triynyl-dodecanoate, and seven known compounds: taraxasteryl acet
Quím. Nova. Publicado em: 2013
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2. Estudo da atividade citotóxica do poliacetileno 5-octa-2, 4, 6-triinil-furan-2(5H)-ona / Study of the cytotoxic activity of polyacetylene 5-octa-2,4,6-triinil-furan-2 (5H)-one
Skin cancers are the most common types of cancer in Brazil, and correspond to around 25% of all malignant tumors recorded. Of these, melanoma represents at least 5% and is characterized by its high metastatic power. The development of anticancer agents from natural products is considered critical to pharmacology, and interest in the development of more effec
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 26/06/2012
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3. Effects of the topical application of an ethyl acetate fraction from Vernonia scorpioides on excisional wounds infected with Staphylococcus aureus in rats
We investigated the healing process on excisional wounds infected with Staphylococcus aureus in rats, treated with 50 µL of ethyl acetate III from Vernonia scorpioides (Lam.) Pers., Asteraceae, rifamycin diethylamide B 25 mg, or saline. The lesions were measured daily and after seven days were surgically removed and histologically processed. The results ind
Revista Brasileira de Farmacognosia. Publicado em: 21/10/2011
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4. A new polyacetylene from Vernonia scorpioides (Lam.) Pers. (Asteraceae) and its in vitro antitumoral activity
A fração diclorometano obtida pelo particionamento do extrato hidroalcoólico obtido das folhas e flores de Vernonia scorpioides (Asteraceae) resultou no isolamento e caracterização de um novo poliacetileno, 5-octa-2,4,6-triinil-furan-2(5H)-ona. A determinação estrutural foi baseada em dados de espectrometria de Ressonância Magnética Nuclear mono e b
Journal of the Brazilian Chemical Society. Publicado em: 2009
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5. Propriedades eletronicas e sÃlitons em cadeias duplas de poliacetileno. / Eletronic properties and solitons in double polyacetylene chain
Neste trabalho à feita uma revisÃo das principais propriedades da molÃcula de poliacetileno sob o ponto de vista da teoria de campos. A seguir, estuda-se duas cadeias de poliacetileno acopladas usando o mesmo formalismo e verifica-se que esse sistema apresenta um gap em sua estrutura de bandas. Esse gap de energia à calculado em termos de uma massa efeti
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 11/12/2008
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6. Alterations in biochemical components in mesta plants infected with yellow vein mosaic disease
Yellow vein mosaic disease of mesta (kenaf, Hibiscus cannabinus L.; and roselle, H. sabdariffa L.) is a new entrant to the disease scenario and it is associated with a novel monopartite Begomovirus. Changes in different biochemical parameters in diseased mesta plants were observed as compared to healthy ones. Isozyme pattern and assays of different enzymes,
Brazilian Journal of Plant Physiology. Publicado em: 2008-12
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7. Avaliação in vitro do mecanismo de ação citotóxica de lactonas sesquiterpênicas e outras substâncias isoladas de Vernonia scorpioides (LAM) PERS / In vitro evaluation of the cytotoxicity mechanism of sesquiterpene lactones and other substances isolated from Vernonia scorpioides (LAM) PERS
The development of new drugs is of utmost importance for the treatment of cancer. Vernonia scorpioides presents antiinflammatory and antitumoral effects. In this study, the investigation of Vernonia scorpioides afforded the hirsutinolide isolate, a mixture of sesquiterpene lactones and an unpublished polyacetylene. We report on the cytotoxic activity and the
Publicado em: 2007
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8. "Nova abordagem matemática para o cálculo da descontinuidade do potencial de troca e correlação de Kohn-Sham e sua aplicação para sistemas atômicos e moleculares (fragmentos de poliacetilenos)" / "New mathematical approach to the calculation of the discontinuity of the Kohn-Sham exchange-correlation potential and its application for atomic systems and polyacetylene fragments"
É bem conhecido que os intervalos proibidos de energia (gaps) de sólidos semicondutores e isolantes calculados resolvendo-se a equação de Kohn-Sham (KS) com alguma aproximação ao funcional de troca e correlação (XC) da teoria do funcional da densidade (density-functional theory, DFT) são geralmente muito pequenos quando comparados com os valores de
Publicado em: 2006
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9. Estudo da estabilidade conformacional do copolimero poliazina-policarbonitrila
The trans-polycarbonitrile polymer presents a strong deviation from the planarity suggesting that this conformation does not correspond to the most stable structure of the system. These non-planarity can affect significantly the electronic properties of the polymer. On the other hand the polyazine derivative, a conjugated polymer, a nitrogen containing analo
Publicado em: 1999
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10. Estudo fitoquimico de Baccharis myriocephala e uso de beta-pineno para a obtenção de orto-mentanos
This thesis was developed into two different parts. Part A involves the phytochemical investigation of roots and aerial parts of Baccharis myriocephala. The specimen was collected in Serra do Mar, São Paulo. From the hexane and methanolic extract we have detected and isolated poliacetylenes, (-)-caryophyllene oxide, baccharis oxide, b-friedelanol and long c
Publicado em: 1997
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11. Soliton dynamics in polyacetylene
The equations of motion of the coupled electron-phonon system are integrated in real time for the model of polyacetylene recently proposed. To illustrate the physical behavior of this nonlinear system we consider the time evolution starting from three physically relevant configurations: (i) end generated soliton, (ii) electron-hole pair generation of a charg
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12. Polarons in DNA
Many experiments have been done to determine how far and how freely holes can move along the stack of base pairs in DNA. The results of these experiments are usually described in terms of a parameter β under the assumption that it describes an exponential decay with distance. The reported values range from β < 0.2/Å to β > 1.4/Å. For the larger values
The National Academy of Sciences.