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Search Results: 1 - 10 of 52 matches for " Photometric "
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Constru??o e calibra??o de uma cela de sedimenta??o gravimétrica para a medi??o fotométrica da distribui??o do tamanho de micropartículas
Salinas-Salas, Gonzalo;Stintz, Michael;Wessely, Benno;
Rem: Revista Escola de Minas , 2009, DOI: 10.1590/S0370-44672009000300014
Abstract: this paper present the theoretical basis, development, implementation and results of from a gravimetric sedimentation cell for determination of size distribution and median diameter of microparticles.
HD 115520, a New δ Scuti Star
Pe?a, J. H.;Sareyan, J. P.;Cervantes-Sodi, B;Pe?a, R;Alvarez, M;Cano, M;Sorcia, M. A.;
Revista mexicana de astronomía y astrofísica , 2007,
Abstract: while performing uvby- β photoelectric photometry of some rr lyrae stars in bootes, acquired in 2005 at the observatorio astronómico nacional, méxico, we also observed several standard stars, hd115520 among them. after the reduction this star showed indications of variability and a compilation of all the data of this star reinforced this conclusion. in view of this, a new observing run was carried out in 2006 during which we were able to demonstrate its variability. we present here the data we acquired as well as some conclusions on its nature as a δ scuti star.
uvby - β photoelectric photometry of Cepheid stars
Pe?a, J. H.;Arellano Ferro, A.;Pe?a-Miller, R.;álvarez, M.;Rosas, Y.;García, H.;Mu?oz, G.;Vargas, B.;Sareyan, J. P.;Guerrero, C. A.;Rentería, A;
Revista mexicana de astronomía y astrofísica , 2010,
Abstract: we present time-series uvby -β photometry of 41 classical cepheid stars. a brief discussion of a comparison between the present data and previous photometric observations is included.
Optimization of the Photometric Enzyme Activity Assay For Evaluating Real Activity of Prolidase
?mer ?zcan,,Mustafa Gültepe,,Osman Metin ?p?io?lu,,Burhanettin Bolat
Türk Biyokimya Dergisi , 2007,
Abstract: Prolidase cleaves the bonds of dipeptides containing proline (X-Pro) and an importantenzyme in collagen metabolism. Prolidase activity is generally determinedby photometric methods based on the measurement of proline levels produced byprolidase. We aimed to investigate the measured prolidase activity is suitable forthe assessment of its physiological activity. Effects of manganese on the enzymeactivation, protein precipitation and reading steps of the photometric method, andinhibitory effect of proline on the enzyme were analyzed. The intra- and inter-assayCVs % were higher than 10 % for photometric method and turnaround timewas 6-8 hours/test. The activation reagent containing manganese was not stableand its concentration was not optimal for enzyme activation. Thus we modifiedthe photometric method by changing manganese concentrations and pH of activatingsolution, eliminating protein-precipitating step, arranging the pH of colorreagent to the pH optimum for ninhidrin reaction and shortened incubation timewith substrate. The inhibitory effect of proline on the prolidase activity even in thephysiological and produced proline concentrations during enzymatic analysis maylimit the analytical performance of prolidase assays. In conclusion, the modifiedphotometric method presented in this study seems to be more reliable than the classicalphotometric method and measured prolidase activity may not reflect the truephysiological activity of enzyme due to proline inhibition.
Examining the M67 Classification as an Open Cluster  [PDF]
Shimmon Naim, Evgeny Griv
International Journal of Astronomy and Astrophysics (IJAA) , 2012, DOI: 10.4236/ijaa.2012.23020
Abstract: The cluster M67 (= NGC 2682) in Cancer is a rich stellar cluster, usually classified as an open cluster. Using our own observations with the 0.4 m telescope, we show that M67 is a tight group of about 1200 stars. The actual radius of the cluster is about 3.1 pc and the average mass of a star in the system is about . We also show that the ratio of the mean kinetic energy of the cluster to its mean gravitational potential energy , while the value predicted by the virial theorem is equal to . So the system is a gravitationally bound. This value of is considered as an evidence of quasi-stability of the cluster and allows us to use the Chandrasekhar-Spitzer relaxation time for M67 Myr as a characteristic dynamical relaxation time of the system. As the cluster is almost twice older its half-life time , it is argued that M67 was in the past (about 4 Gyr ago, close to its forma-tion) a relatively small ( stars) globular cluster, but got “open cluster” shape due to the dynamical evapora-tion of the majority of its stars.
Fast determination of minoxidil by photometric flow titration
Sousa, R. A. de;Semaan, F. S.;Baio, J. A. F.;Cavalheiro, E. T. G.;
Eclética Química , 2005, DOI: 10.1590/S0100-46702005000300010
Abstract: a photometric flow titration based on the redox reaction between kmno4 and minoxidil is described. the best titration results were observed at 3.20 x 10-4 mol l-1 kmno4 and 1.00 x 10-3 mol l-1 minoxidil, using the minoxidil solutions as titrant. the flow rate was fixed at 17 ml min-1 and the titrant was added to the system in aliquots of 500 μl, the color changes were monitored at 550 nm. the method was applied to commercial samples and compared with the results from a chromatographic procedure. recoveries from 97.6 to 102.8 % were observed depending on the sample. comparison with the chromatographic procedure reveled relative errors of 3.5 - 4.0 %.
Aplicación del Método Fotométrico para la Detección de la Distribución de Tama?o de Micro Partículas
Salinas-Salas,G.; Stintz,M.; Wessely,B.;
Información tecnológica , 2005, DOI: 10.4067/S0718-07642005000400010
Abstract: this study deals with the theoretical basis, development, implementation and results obtained when using a gravimetric sedimentation cell to detect the size distribution and the average diameter of a sample of microscopic particles using an optical system based on the measurement of the extinction or decline of a photon flux from a beam of light passing through an aqueous suspension of the particles in question. the cell was built in modular form and its calibration and tests were done using a suspension composed of known-size particles of amorphous silicon dioxide (geltech s 1500) with a nominal average diameter of 1.5 μm in water. the results showed that it was possible to determine the size distribution of the micro-particles with precision and at low cost, which could permit its' useful application in industry.
CONSTRUCCIóN Y CALIBRACIóN DE UNA CELDA DE SEDIMENTACIóN GRAVIMéTRICA PARA LA MEDICIóN FOTOMéTRICA DE LA DISTRIBUCIóN DE TAMA?O DE MICRO PARTíCULAS
Salinas-Salas,Gonzalo; Stintz,Michael; Wessely,Benno;
Revista Facultad de Ingeniería - Universidad de Tarapacá , 2005, DOI: 10.4067/S0718-13372005000200005
Abstract: this paper present the theoretical basis, development, implementation and results of from a gravimetric sedimentation cell for determination of size distribution and median diameter of a sample of micro particles. the measurement is based on the transmittance of light through a suspension particles in water. the cell was built in modular form and was calibrated with suspensions of amorphous silicion dioxid with a median diameter of 1.5 μm. the results indicate that the sedimentation cell is very simple to use and that the size distribution of micro particles can be determined at low cost. this procedure may be conveniently applied in the many industrials processes.
Water Vapor Corrections to Mid-Infrared Photometry
Hiriart, David;Salas, Luis;
Revista mexicana de astronomía y astrofísica , 2007,
Abstract: we explore water vapor corrections for the san pedro mártir mid-infrared photometric system cid. atmosphere opacity is measured by a 210 ghz radiometer. by using the results of the atm code, we propose a linear relationship between 210 ghz opacity and water vapor content. this relation allows us to determine the water vapor content in the atmosphere from opacity measurements at the radiometer frequency. we also obtain a relation between water vapor content and mid-infrared opacity by using the modtran 3 atmospheric model. thus, through the water vapor we obtain a relation that connects millimeter opacity to mid-infrared opacity under clear sky conditions. we tested this relation with measurements made at san pedro mártir of these two opacities.
Physical parameters of seven field RR Lyrae Stars in bootes
Pe?a, J. H.;Arellano Ferro, A.;Pe?a Miller, R.;Sareyan, J. P.;álvarez, M.;
Revista mexicana de astronomía y astrofísica , 2009,
Abstract: str?mgren uvby - β photometry is reported for the rr lyrae stars ae, rs, st, tv, tw, uu, and xx in bootes. the physical parameters m/m log(l/l), mv, log teff and [fe/h], have been estimated from the fourier decomposition of the light curves and the empirical calibrations developed for this type of stars. the obtained [fe/h] values are compared with those calculated from the δs index for some sample stars. it was found that reddening in the zone is negligible compared to that shown by several objects in the same sky zone. from that, distance to the stars was calculated. the variation of the unreddened indexes (b-y)0 and c1 along the pulsational cycle allows the direct comparison with the theoretical grids and, hence, an independent determination of teff and log g.
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