A simple and rapid method has been developed for the determination of ascorbic acid in fruit and pharmaceutical products. The method is based on the measurement of the reaction rate between ammonium molybdate and ascorbic acid in acidic media. The reaction was monitored spectrophotometrically at 800 nm by fixed-time and variable-time methods. The calibration graph was linear in the range of...

Persistence is the property, for differential equations in R(n), that solutions starting in the positive orthant do not approach the boundary of the orthant. For chemical reactions and population models, this translates into the non-extinction property: provided that every species is present at the start of the reaction, no species will tend to be eliminated in the course of the reaction. This ...

The formation and disappearance of a photosensitive species during the reaction of reduced cytochrome c oxidase (putatively a3II.O2), EC 1.9.3.1, has been followed by (a) mixing a3II.CO with O2 in a stopped flow apparatus; (b) initiating the oxygen-oxidase reaction by removing CO with a laser flash; (c) probing the reaction mixture for photosensitivity with a second laser flash. Photosensitivit...

effect of water gas shift reaction (co+h2o=co2+h2) on wustite reduction has been investigated by a transient, non-isothermal mathematical model based on grain model. in this model, wustite porous pellet is reduced using syngas, namely a mixture of hydrogen, carbon monoxide, carbon dioxide and water vapor. for this purpose, governing equations containing continuity equation of species and energy...

a simple and rapid method has been developed for the determination of ascorbic acid in fruit and pharmaceutical products. the method is based on the measurement of the reaction rate between ammonium molybdate and ascorbic acid in acidic media. the reaction was monitored spectrophotometrically at 800 nm by fixed-time and variable-time methods. the calibration graph was linear in the range of 5 0...

The stability constants and complexation reaction between L-glutamine, L-arginine andglycine with Zn (II) , Co (II) and Ni (II) were studied potentiometrically in aqueous solution at25° C and μ=0.1 M KNO3. The overall stability constants log β´s of all species are obtained bycomputer refinement of pH-volume data using BEST computer program. Several models weretested and the lowest δFIT, the bes...

with regard to the mutual relations between plant and soil as the main component of rangeland ecosystems, this research has been identified the indicator species in environmental conditions of dry regions as the most important tools in ecological management of these ecosystems. therefore the steppe and dry rangelands of kooh - e- namak in qom province was selected. sampling was done by plot in ...

Here, Tj is a time period that species X spent in state n, and Tsim is the total simulation time. For the species X1 shown in Figure 1 of the manuscript, as first sight, one might think that P (X1 = 0) << P (X1 = 1) because X1 = 1 during 19 of the 20 simulated time steps. In stochastic simulations, reaction events are irregular due to their stochastic nature. In this particular example, the fir...

In this study, Dunaliella has been isolated in Jun. 2014 from Hoz-e Soltan and Aran-va-Bidgol salt Lakes (Iran). The isolates have been identified morphologically with the aid of simple light and invert microscope after isolation and purification on their specific medium (Moh202). By using molecular techniques such as polymerase chain reaction (PCR) and amplification of 18S rDNA gene primers, f...