19 research outputs found
Bioactivity Of Flavonoids Isolated From Lychnophora Markgravii Against Leishmania Amazonensis Amastigotes
No full textThe bioactivity of the flavonoids pinostrobin (1), pinocembrin (2), tectochrysin (3), galangin 3-methyl ether (4), and tiliroside (5) isolated from Lychnophora markgravii aerial parts was investigated in vitro against amastigote stages of Leishmania amazonensis. The compounds were isolated by several chromatographic techniques and their chemical structures were established by ESI-MS and NMR spectroscopic data. The flavonoids 1 and 3 were the most active compounds; they markedly reduced the viability of Leishmania amastigotes. © 2009 Verlag der Zeitschrift für Naturforschung, Tübingen.647-8509512Agrawal, P.K., (1989) Carbon-13 NMR of Flavonoids, p. 564. , Elsevier, AmsterdamCoile, N.C., Jones, S.B., Lychnophora (Compositae: Vernonieae), a genus endemic to the Brazilian planalto (1981) Brittonia, 33, pp. 528-542Gobbo-Neto, L., Lopes, N.P., Online identification of chlorogenic acids, sesquiterpene lactones, and flavonoids in the Brazilian arnica Lychnophora ericoides Mart. (Asteraceae) leaves by HPLC-DAD-MS and HPLC-DAD-MS/MS and a validated HPLC-DAD method for their simultaneous analysis (2008) J. Agric. Food Chem, 56, pp. 1193-1204Grael, C.F.F., Vichnewski, W., Souza, G.E.P., Lopes, J.L.C., Albuquerque, S., Cunha, R.W., A study of the trypanocidal and analgesic properties from Lychnophora granmongolense (Duarte) Semir & Leitao Filho (2000) Phytother. Res, 14, pp. 203-206Harborne, J.B., The Flavonoids: Advances in Research since 1986 (1996) The Flavonoids, pp. 450-453. , Chapman and Hall, London. Markam K. R. and Geiger H. (1994), 1H nuclear magnetic resonance spectroscopy of flavonoids and their glycosides in hexadeuterodimethylsufoxide Harborne J. B., ed.). Chapman and Hall, LondonMosmann, T., Rapid colorimetric assay for cellular growth and survival: Application to proliferation and cytotoxicity assays (1983) J. Immunol. Methods, 65, pp. 55-63Pral, E.M.F., Moitinho, M.L.R., Balanco, J.M.F., Teixeira, J.R., Mider, R.V., Alfieri, S.C., Growth phase and medium pH modulate the expression of proteinase activities and the development of megasomes in axenically cultivated Leishmania (Leish-mania) amazonensis amastigotes-like organisms (2003) J. Parasitol, 89, pp. 35-43Robinson, H., Generic and subtribal classification of American Vernonieae (1999) Smithson. Contrib. Bot, 89, pp. 1-116Sakamoto, H.T., Flausino, D., Catellano, E.E., Stark, C.B.W., Gates, P.J., Lopes, N.P., Sesquiterpene lactones from Lychnophora ericoides (2003) J. Nat. Prod, 66, pp. 693-695Salvador, M.J., Ferreira, E.O., Pral, E.M.F., Alfieri, S.C., Albuquerque, S., Ito, I.Y., Dias, D.A., Bioactivity of crude extracts and some constituents of Blutaparon portulacoides (Amaranthaceae) (2002) Phytomedicine, 9, pp. 566-571Santos, M.D., Gobbo-Neto, L., Albarella, L., Souza, G.E.P., Lopes, N.P., Analgesic activity of di-caffeoylquinic acids from roots of Lychnophora ericoides (arnica da serra) (2005) J. Ethnopharmacol, 96, pp. 545-549Sartori, F.T., Sacilotto, A.C.B., Lopes, J.L.C., Lopes, N.P., Vichnewski, W., Phytochemical study of Lychnophora markgravii (Asteraceae) (2002) Biochem. Syst. Ecol, 30, pp. 609-612Takeara, R., Albuquerque, S., Lopes, N.P., Lopes, J.L.C., Trypanocidal activity of Lychnophora staavioides Mart. (Vernonieae, Asteraceae) (2003), 10, pp. 490-493Taleb-Contini, S.H., Salvador, M.J., Balanco, J.M.F., Albuquerque, S., de Oliveira, D.C.R., Antiprotozoal effect of crude extracts and flavonoids isolated from Chromolaena hirsuta (Asteraceae) (2004) Phytother. Res, 18, pp. 250-25
Author Correction: Rapid increase in the risk of heat-related mortality.
No full textCorrection to: Nature Communicationshttps://doi.org/10.1038/s41467-023-40599-x, published online 24 August 2023 The original version of this Article omitted from the author list the 17th author, “Multi-Country Multi-City (MCC) collaborative research network”, which is the consortium providing the mortality data. A list of consortium authors and their affiliations are provided in the HTML version of this Correction. Part of the Author Contributions statement was incorrectly given and should have read ‘A.M.V.C., E.M.F., B.A., M.D.S.Z.S.C., Y.L.G., Y.G., Y.H., V.H., J.K., E.L., D.R., N.R., N.S., S.S., A.U., A.G. and the MCC were involved in resources and data curation.’ In addition, the primary affiliation ‘Climate Research Foundation (FIC), Madrid, Spain’ for Dominic Roye was missing
Thermodynamic assessment of the KF-ThF<sub>4</sub>, LiF-KF-ThF<sub>4</sub> and NaF-KF-ThF<sub>4</sub> systems
No full textA thermodynamic assessment of the KF-ThF4 binary system using the CALPHAD method is presented, where the liquid solution is described by the modified quasichemical formalism in the quadruplet approximation. The optimization of the phase diagram is based on experimental data reported in the literature and newly measured X-ray diffraction and differential scanning calorimetry data, which have allowed to solve discrepancies between past assessments. The low temperature heat capacity of α-K2ThF6 has also been measured using thermal relaxation calorimetry; from these data the heat capacity and standard entropy values have been derived at 298.15 K: Cp,mo(K2ThF6,cr,298.15K)=(193.2±3.9) J·K-1·mol-1 and Smo(K2ThF6,cr,298.15K)=(256.9±4.8) J·K-1·mol-1. Taking existing assessments of the relevant binaries, the new optimization is extrapolated to the ternary systems LiF-KF-ThF4 and NaF-KF-ThF4 using an asymmetric Kohler/Toop formalism. The standard enthalpy of formation and standard entropy of KNaThF6 are re-calculated from published e.m.f data, and included in the assessment of the ternary system. A calculated projection of the NaF-KF-ThF4 system at 300 K and the optimized liquidus projections of both systems are compared to published phase equilibrium data at room temperature and along the LiF-LiThF5 and NaF-KThF5 pseudobinaries, with good agreement.RST/Reactor Physics and Nuclear Material
Role of ¿1-pyrroline-5-carboxylate dehydrogenase supports mitochondrial metabolism and host-cell invasion of Trypanosoma cruzi
No full textProline is crucial for energizing critical events throughout the life cycle of Trypanosoma cruzi, the etiological agent of Chagas disease. The proline breakdown pathway consists of two oxidation steps, both of which produce reducing equivalents as follows: the conversion of proline to ¿1-pyrroline-5-carboxylate (P5C), and the subsequent conversion of P5C to glutamate. We have identified and characterized the ¿1-pyrroline-5-carboxy- late dehydrogenase from T. cruzi (TcP5CDH) and report here on how this enzyme contributes to a central metabolic pathway in this parasite. Size-exclusion chromatography, two-dimen- sional gel electrophoresis, and small angle x-ray scattering analysis of TcP5CDH revealed an oligomeric state composed of two subunits of six protomers. TcP5CDH was found to complement a yeast strain deficient in PUT2 activity, confirming the enzyme’s functional role; and the biochemical parameters (Km, kcat, and kcat/Km) of the recombinant TcP5CDH were determined, exhibiting values comparable with those from T. cruzi lysates. In addition, TcP5CDH exhibited mitochondrial staining during the main stages of the T. cruzi life cycle. mRNA and enzymatic activity levels indicated the up-regulation (6-fold change) of TcP5CDH during the infective stages of the parasite. The participation of P5C as an energy source was also demonstrated. Overall, we propose that this enzymatic step is crucial for the viability of both replicative and infective forms of T. cruzi
On the Activities of Cr and C in Molten Fe-C-Cr Alloys
No full textapplication/pdfBy constructing the following electrode concentration cell, the author measured the e.m.f. corresponding to the change in Cr and C in Fe-C-Cr alloys at about 1, 540℃ : 【○!-】 Fe, Cr|SiO_2, CaO, Cr-oxide, MgO|Fe. Cr, C 【○!+】 From the following equation the activity of Cr in this alloys was determined for the range of CrT log α_ Fe-Cr binary alloys obey Raoult's law but Fe-C-Cr alloys show gradually negative deviation from Raoult's law on the addition of C, and the effect of C on the activity coefficient of Cr was discussed by using interaction parameter γ^C_ In addition, the effect of Cr on the activity coefficient of C was also discussed. Furthermore, the behaviors of Cr-oxide in molten slag were considered from oxygen potential which controls the system. And the decarburization limit in Fe-C-Cr alloys was calculated from experimental results.紀要類(bulletin)849552 bytesdepartmental bulletin pape
A study of projectile motion on impact with thin aluminium plates
No full textIncludes bibliographical references.A new technique has been developed to examine projectile motion on impact with thin aluminium plates. A brief review of the field of penetration is given to show where the need for the present research arises. This is followed by an examination of alternative methods which could be used to determine penetration behaviour of projectiles and a discussion of their respective merits. Any impact phenomenon of elastic bodies is accompanied by inherent vibrations. Because of the greater sensitivity of the method used by the author over previous methods, vibrations set up in the projectile sensing mechanism played a very significant role in the penetration process. To take account of the vibration phenomenon, recourse was made to Masket's (1949) work which enables the motion of the centre of mass of the projectile to be determined from a knowledge of the motion of any point on the projectile. The new technique has many advantages over previous methods, the main one being the simultaneous production of deceleration-time data as the projectile penetrates the target material. Although the data must still be processed to remove superimposed vibrations, it does not have to undergo the drastic smoothing process of double differentiation used in previous methods. Because of this, the overall characteristic shape of the deceleration-time plot is preserved
Cork–polymer biocomposites: mechanical, structural and thermal properties
No full textThis work addresses to the preparation of biocomposites resulting from the combination of different biodegradable aliphatic polyesters with cork (30 wt.%). The lignocellulosic biomass with closed cellular structure was compounded with poly(L-lactic acid) (PLLA), polyhydroxybutyrate-co-hydroxyvalerate (PHBV), poly-ε-caprolactone (PCL) and starch-poly-ε-caprolactone (SPCL) blend using a twin-screw extruder prior to injection moulding into tensile samples. The physico-mechanical and thermal properties of the matrices and the bio-based cork composites were investigated. This study shows that the addition of cork contributes to produce lightweight materials using PLLA and PHBV matrices and promotes an increase on the stiffness of PCL. The fracture morphology observations showed good physical corkâ matrix bonding with absence of voids or cavities between cork and the bio-based polyesters. Cork increases the crystallinity degree of the biocomposites. These findings suggest that the corkâ polymer biocomposites are a viable alternative to develop more sustainable composite materials, such as automotive interior parts and bio-based caps for wine bottles as it has been shown as proof-of-concept.The work was performed within the project of Corticeira Amorim S.G.P.S. on the development of new products based in/with cork. The authors gratefully acknowledge the financial support, through the COMPETE/QREN/EU funding program in the project with acronym NovelComp (QREN FCOMP-01-0202-FEDER-003107). The author E.M.F. acknowledges the financial support from the Portuguese Foundation for Science and Technology (FCT) and POPH/FSE for the post-doctoral grant (SFRH/BPD/96197/2013)
Detection of an End-Ring Fault in Asynchronous Machines by Spectrum Analysis of the Observed Electromagnetic Torque
No full textFor asynchronous machines, 20% of the failures are due to the rotor [1] and particularly the end-ring fault of cage motors. Studies [2, 4] have shown that a rator fault generates flux harmonics which induce in term of harmonics in the stator currents. So, the analysis of the torque which is the product of these two quantities, must give a better information on the faults. In this paper a new technique is presented allowing the diagnostic of an end-ring fault of a cage threephase asynchronous machine. Previous researches by the author [5] have given the expression of the instantaneous electromagnetic torque with these defects influence. It has been observed actually that the ruptures influence greatly this quadratic quantity. The torque was calculated from the line currents and the e.m.f across flux sensors placed in the stator windings. In this method, the flux sensors are not essential to determine the electromagnetic torque. The rotor flux can be directly estimated by using an observer. This study presents how a model of the asynchronous machine is used to build the observer.
Surface temperature measurement of metal undergoing induction heating
No full textIt is the object of this thesis to investigate the possibility of using thermoelectric pyrometry for surface temperature measurement of metal undergoing induction heating. The temperature range under investigation, as stated before, is 400 °F to 1250 °F. This research may actually be treated by two sections.
The first section concerns the methods of using thermocouples for ordinary surface temperature measurements. The second section concerns the effect, if any, on thermocouple e.m.f. readings while it is measuring the surface temperature of a metal undergoing induction heating. The first section of the investigation has been well covered by literature and will be discussed under Review of Literatures . The main body of the thesis will be composed of experiments dealing with the second part of this investigation; that is, the investigation of the induction heating effect on thermocouples as a temperature sensing element, since, to the knowledge of the author, there has not yet been any comprehensive attempt made in that direction --Introduction, pages 1-2
Clonagem e expressão da enzina tripanotiona redutase de Leishmania braziliensis e atividade leishmanicida de chalconas
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Programa de Pós-graduação em Biotecnologia, Florianópolis, 2011O presente estudo teve por objetivo avaliar atividade leishmanicida in vitro de chalconas trimetoxiladas contra formas promastigotas de cultura e amastigotas intracelulares de L. braziliensis e L. chagasi em células da linhagem J744-A1 e macrófagos murinos derivados de medula. Além disso, foi realizada a clonagem e a expressão da enzima tripanotiona redutase de L. braziliensis com o objetivo de implementar uma metodologia para avaliação de compostos inibidores desta enzima. Trinta e cinco das 70 chalconas avaliadas mostraram atividade leishmanicida contra formas promastigotas, com CI50 variando de 1,31 a 32,54 µM, e oito destas mostraram índices de seletividade maiores que 20 contra formas promastigotas de L. braziliensis e L. chagasi. Nos ensaios contra formas amastigotas intracelulares de L. braziliensis na linhagem J744-A1, as chalconas M10 e M30 apresentaram CI50 de 0,13 e 0,34 µM, respectivamente, sendo as mais seletivas para o parasito. Em macrófagos murinos infectados a CI50 variou de 2,2 a 6,5 µM para L. braziliensis e de 2,4 a 8,7 µM para L. chagasi. De maneira geral, a espécie dermotrópica mostrou-se mais sensível que a viscerotrópica aos compostos. A expressão da tripanotiona redutase recombinante de L. braziliensis (LbTR) resultou em uma proteína de 53,5kDa. A atividade biológica da enzima foi confirmada pela redução do substrato (tripanotiona) e sua inibição pelos compostos padrão (clomipramina e ácido gálico). Ensaios de inibição in vitro da atividade enzimática com as 8 chalconas ativas mostraram que apenas dois compostos (D08 e M17) foram capazes de inibir moderadamente a atividade da enzima (58% e 63%). As chalconas trimetoxiladas apresentaram um potente efeito leishmanicida in vitro, constituindo-se em moléculas protótipo promissoras para o desenvolvimento de novos agentes leishmanicidas
