Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Espermidina e espermina exogena na micropropaga o de Aloe vera (L.) Burm Es permidine y espermine exógeno en el micropropagación de Aloe vera (L.) Burm Exogenous spermidine and spermine in micropropagation of Aloe vera (L.) Burm
Gilda Mógor,Giuseppina Pace Pereira Lima,Atila Mogor
Revista Cubana de Plantas Medicinales , 2007,
Abstract: ápices caulinares de Aloe vera L. Burm. foram inoculados em meios de cultura. O experimento foi dividido em duas fases. Na fase I diferentes concentra es e combina es de NAA e BAP foram adicionadas ao meio MS . Na fase II, p lantas provenientes de MS foram inoculadas em meio contendo ou n o espermidina e/ou espermina. Na fase I, os melhores resultados para produ o de massa e perfilhamento ocorreram em MS + 8,88 m mol.L -1 BAP + 5,36 m mol.L -1 NAA e n o foi observado enraizamento. Plantas submetidas aos tratamentos com poliaminas (10 mM) apresentaram emiss o de raízes na fase II, sugerindo possível efeito indutor, quando usadas isoladamente durante a rizogênese. N o foram notados indícios de oxida o no meio de cultura contendo poliaminas. O uso de espermidina no meio de cultura promoveu maior incremento de massa e o maior número de perfilhos foi obtido com o uso da combina o das poliaminas. ápices caulinares de plantas de Aloe vera L. Burm. fueron inoculados en medios de cultivo. El experimento fue dividido en dos fases. En la fase l diferentes concentraciones y combinaciones de NAA y BAP fueron adicionadas al medio MS. En la fase II, plantas provenientes del tratamiento MS fueron inoculadas en medio que contenía, o no, espermidina y/ o espermina. En la fase I, los mejores resultados para producción de masa y brotaciones ocurrieron con el uso de MS + 8,88 m mol L -1 BAP + 5,36 m mol L -1 NAA y no indujeron al enraizamiento. Las plantas sometidas a los tratamientos con espermidina o espermina (10 mM) presentaron emisión de raíces durante la fase II, sugiriendo un posible efecto inductor, cuando fueron usadas aisladamente durante la rizogénesis. No fueron notados indicios de oxidación en el medio de cultivo que contenía poliaminas. El uso de espermidina en el medio de cultivo promovió mayor incremento de masa y un mayor número de brotaciones fue obtenido con el uso de la combinación de las poliaminas. The lateral shoots of the Aloe vera L. Burm have been inoculated in culture medium. The work has been divided in two phases. In the phase I different concentrations of NAA and BAP were added to the MS . In the phase II, plants proceeding of the MS were inoculated in medium containing or not spermidine and/or spermine. In the phase I the best results for mass production and shooting came out with the use of MS + 8,88 m mol L -1 BAP + 5,36 m mol L -1 NAA and these treatments didn′t induce the rooting. Plants submitted to treatments with polyamines presented emission of roots during the phase II, suggesting possible inductor effect when used by isolated me
Medida da difus o de fluídos em sólidos amorfos por atenua o de raios gama  [cached]
Carlos Roberto Appoloni,Antonio Tannous
Semina : Ciências Sociais e Humanas , 1979, DOI: 10.5433/
Abstract: This article presents theoretical and experimental procedure used in the study of fluid diffusion in amorphous solids by gamma ray atenuation. It is also presented a brief experimental study of water difussion in concrete, qualitatively comparing with a theoretical and experimental study of water diffusion in Cerrado soil. No presente trabalho discute-se o formalismo teórico e o procedimento experimental para o estudo do movimento de fluídos em sólidos amorfos por atenua o de raios gama. Apresenta-se também um breve estudo experimental da difus o de água em concreto, comparando-se qualitativamente com estudo teórico e experimental da difus o de água em solo do tipo Cerrado.
Estresse salino associado à aplica??o exógena de espermidina no acúmulo de glicina betaína em Guandu
Destro, Moacir Vinícius Pereira;Santos, Durvalina Maria Mathias dos;Vollet, Vanessa Cristiane;Marin, Ad?o;Banzatto, David Ariovaldo;
Bragantia , 2008, DOI: 10.1590/S0006-87052008000300006
Abstract: this study was undertaken to evaluate the effect of salt stress associated to exogenous spermidine (spd) application on the accumulation of glycine betaine in the pigeonpea genotypes iac fava larga and caqui. the use of this compatible osmolyte as a biochemical-physiological indicator of salinity was also evaluated. the experiment was carried out at unesp, faculdade de ciências agrárias e veterinárias, in jaboticabal (sp), from october to november 2005, in a grow room with irradiance of 190 μmol m-2 s-1, photoperiod of 12 hours, temperature set to 25 oc and the rh to 40%. seeds were sowed in sterile sand with adequate water supply. after 10 days, seedlings were transferred to nutritive solution during 20 days for acclimation. the experiment was then arranged in randomized block design in a 2 x 2 x 4 factorial, corresponding to the genotypes (iac fava larga and caqui), spd rates (control and 0.5 mm) and salt stress (0, 20, 60 and 80 mm nacl). the levels of glycine betaine were determined after 20 days under stress. our results show that glycine betaine can be used as a biochemical-physiological marker of salt stress in the 'iac fava larga'.
NaCl nanodroplet on NaCl(100) at the melting point  [PDF]
T. Zykova-Timan,U. Tartaglino,D. Ceresoli,W. Sekkal,E. Tosatti
Physics , 2004, DOI: 10.1016/j.susc.2004.06.110
Abstract: The self-wetting properties of ionic crystal surfaces are studied, using NaCl(100) as a prototype case. The anomalously large contact angle measured long ago by Mutaftschiev is well reproduced by realistic molecular dynamics simulations. Based on these results, and on independent determinations of the liquid-vapor and the solid-vapor interface free energy, an estimate of the solid-liquid interface free energy is extracted. The solid-vapor surface free energy turns out to be small and similar to the liquid-vapor one, providing a direct thermodynamic explanation of the reduced wetting ability of the ionic melt.
NaCl Potentiates Human Fibrocyte Differentiation  [PDF]
Nehemiah Cox, Darrell Pilling, Richard H. Gomer
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0045674
Abstract: Excessive NaCl intake is associated with a variety of fibrosing diseases such as renal and cardiac fibrosis. This association has been attributed to increased blood pressure as the result of high NaCl intake. However, studies in patients with high NaCl intake and fibrosis reveal a connection between NaCl intake and fibrosis that is independent of blood pressure. We find that increasing the extracellular concentration of NaCl to levels that may occur in human blood after high-salt intake can potentiate, in serum-free culture conditions, the differentiation of freshly-isolated human monocytes into fibroblast-like cells called fibrocytes. NaCl affects the monocytes directly during their adhesion. Potassium chloride and sodium nitrate also potentiate fibrocyte differentiation. The plasma protein Serum Amyloid P (SAP) inhibits fibrocyte differentiation. High levels of extracellular NaCl change the SAP Hill coefficient from 1.7 to 0.8, and cause a four-fold increase in the concentration of SAP needed to inhibit fibrocyte differentiation by 95%. Together, our data suggest that NaCl potentiates fibrocyte differentiation. NaCl-increased fibrocyte differentiation may thus contribute to NaCl-increased renal and cardiac fibrosis.
In vitro NaCl tolerances of Artemisia dracunculus  [PDF]
International Journal of Medicinal and Aromatic Plants , 2012,
Abstract: In vitro evaluation of salinity effects on Artemisia dracunculus was investigated using five NaCI concentrations (0, 25, 50, 100 and 150 mM). The exposure to NaCl in multiplication and root stages affects, all the vegetative parameters which showed significant decrease with increaseing NaCl concentrations in the both stage. Biochemical and chemical parameters such as pigments, Na+, K+ and Cl- in plant were tested in order to put forward the relative tolerance of plant to salinity. Additionally, electrophoretic analysis of total soluble protein (SDS-PAGE) has revealed that plant subjected to NaCl showed induction in the synthesis of new polypeptides. This finding suggest that, the response of Artemisia dracunculus to salt stress may be accomplished by synthesis of new protein which could be in turn contribute to select a salt resistant lines. The highest values of estragol were obtained under non-salinity condition (control) using HPLC analysis .Salinity stress significantly decreased estragol.
Pretreatment with Spermidine Reverses Inhibitory Effects of Salt Stress in Two Rice (Oryza sativa L.) Cultivars Differing in Salinity Tolerance  [PDF]
P. Saleethong,J. Sanitchon,K. Kong-ngern,P. Theerakulpisut
Asian Journal of Plant Sciences , 2011,
Abstract: Environmental stresses including soil salinity are severely affecting rice growth and productivity. The triamine Spermidine (Spd), a member of Polyamines (PAs), a group of phytohormone-like natural amine compounds has been shown to play essential roles in salt stress tolerance in many important crop plants. The effects of exogenously supplied Spd were investigated in two rice cultivars differing in salt tolerance level to determine the roles of Spd on the modulation of physiological parameters related to salt-stress responses. Thirty day-old seedlings of two rice cultivars, Pokkali (salt-tolerant) and KDML 105 (salt-sensitive), grown in nutrient solution were exposed or not to 1 mM Spd for 24 h before submitted to salinized solution containing 150 mM NaCl for 7 days. Salinity stress resulted in significant reduction in plant height, fresh and dry weight of both cultivars but Spd pretreatment significantly increased these growth parameters only in Pokkali. Salt-stress induced considerable disturbance in several physiological processes inhibitory for growth including chlorophyll loss, accumulation of hydrogen peroxide and increase in lipid peroxidation, increased electrolyte leakage and increase in Na+/decrease in K+/Na+. Spd pretreatment led to the reversal of those inhibitory effects in both cultivars. This study showed that exogenous Spd can be applied as short-term pretreatment prior to introduction of salt stress to help elevate salt tolerance of rice and confirmed earlier observations that exogenous Spd offered protective roles on salinity-stressed rice by stabilizing membrane, scavenging free radicals and maintaining K+/Na+ status.
Color centers in NaCl by hybrid functionals  [PDF]
Wei Chen,Christoph Tegenkamp,Herbert Pfnür,Thomas Bredow
Physics , 2010, DOI: 10.1103/PhysRevB.82.104106
Abstract: We present in this work the electronic structure and transition energies (both thermodynamic and optical) of Cl vacancies in NaCl by hybrid density functionals. The underestimated transition energies by the semi-local functional inherited from the band gap problem are recovered by the PBE0 hybrid functional through the non-local exact exchange, whose amount is adjusted to reproduce the experimental band gap. The hybrid functional also gives a better account of the lattice relaxation for the defect systems arising from the reduced self-interaction. On the other hand, the quantitative agreement with experimental vertical transition energy cannot be achieved with hybrid functionals due to the inaccurate descriptions of the ionization energies of the localized defect and the positions of the band edges.
Melting and Grüneisen parameters of NaCl at high pressure
中国物理 B , 2004,
Abstract: The Buckingham potential has been employed to simulate the melting and thermodynamic parameters of sodium chloride (NaCl) using the molecular dynamics (MD) method. The constant-volume heat capacity and Grüneisen parameters have been obtained in a wide range of temperatures. The calculated thermodynamic parameters are found to be in good agreement with the available experimental data. The NaCl melting simulations appear to validate the interpretation of superheating of the solid in the one-phase MD simulations. The melting curve of NaCl is compared with the experiments and other calculations at pressure 0-30GPa range.
Sodium Chloride, NaCl/ε : New Force Field  [PDF]
Raul Fuentes-Azcatl,Marcia C. Barbosa
Physics , 2015,
Abstract: A new computational model for Sodium Chloride, the NaCl/{\epsilon}, is proposed. The Force Fields employed here for the description of the NaCl is based on a set of radial particle-particle pair potentials involving Lennard-Jones (LJ) and Coulombic forces. The parameterization is obtained fitting the density of the crystal and the density and the dielectric constant of the mixture of salt with water at diluted solution. Our model shows good agreement with the experimental values for the density and surface tension for the pure system and for the density, the viscosity, the diffusion, and the dielectric constant for the mixture with water at various molal concentrations. The NaCl/{\epsilon} together with the water TIP4P/{\epsilon} model provide a good approximation for studying electrolyte solutions.
Page 1 /100
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.