scholarly journals A kinetic study of hypoxanthine oxidation by milk xanthine oxidase

1988 ◽  
Vol 254 (3) ◽  
pp. 829-833 ◽  
Author(s):  
J Escribano ◽  
F Garcia-Canovas ◽  
F Garcia-Carmona
Keyword(s):  
Mathematical Model ◽  
Uric Acid ◽  
Kinetic Study ◽  
Xanthine Oxidase ◽  
Kinetic Parameters ◽  
Time Course ◽  
Reaction Sequence ◽  
Acid Product ◽  
The Mathematical Model

The course of the reaction sequence hypoxanthine→xanthine→uric acid catalysed by xanthine:oxygen oxidoreductase from milk was investigated on the basis of u.v. spectra taken during the course of hypoxanthine and xanthine oxidations. It was found that xanthine accumulated in the reaction mixture when hypoxanthine was used as a substrate. The time course of the concentrations of hypoxanthine, xanthine intermediate and uric acid product was simulated numerically. The mathematical model takes into account the competition of substrate, intermediate and product and the accumulation of the intermediate at the enzyme. This type of analysis permits the kinetic parameters of the enzyme for hypoxanthine and xanthine to be obtained.

scholarly journals Effect of NADH on hypoxanthine hydroxylation by native NAD+-dependent xanthine oxidoreductase of rat liver, and the possible biological role of this effect

1981 ◽  
Vol 200 (3) ◽  
pp. 597-603 ◽  
Author(s):  
Z W Kamiński ◽  
M M Jezewska
Keyword(s):  
Uric Acid ◽  
Rat Liver ◽  
Time Course ◽  
De Novo ◽  
Xanthine Oxidoreductase ◽  
Reaction Sequence ◽  
Oxidoreductase Activity ◽  
Dependent Activity ◽  
Sepharose 4B

The course of the reaction sequence hypoxanthine leads to xanthine leads to uric acid, catalysed by the NAD+-dependent activity of xanthine oxidoreductase, was investigated under conditions either of immediate oxidation of the NADH formed or of NADH accumulation. The enzymic preparation was obtained from rat liver, and purified 75-fold (as compared with the 25000 g supernatant) on a 5′-AMP-Sepharose 4B column; in this preparation the NAD+-dependent activity accounted for 100% of total xanthine oxidoreductase activity. A spectrophotometric method was developed for continuous measurements of changes in the concentrations of the three purines involved. The time course as well as the effects of the concentrations of enzyme and of hypoxanthine were examined. NADH produced by the enzyme lowered its activity by 50%, resulting in xanthine accumulation and in decreases of uric acid formation and of hypoxanthine utilization. The inhibition of the Xanthine oxidoreductase NAD+-dependent activity by NADH is discussed as a possible factor in the regulation of IMP biosynthesis by the ‘de novo’ pathway or (from unchanged hypoxanthine) by ther salvage pathway.

scholarly journals Uptake of cadmium by Pseudokirchneriella supcapitata

2005 ◽  
Vol 48 (6) ◽  
pp. 1027-1034 ◽  
Author(s):  
Magela Paula Casiraghi ◽  
Samuel Luporini ◽  
Eduardo Mendes da Silva
Keyword(s):  
Mathematical Model ◽  
Metal Ions ◽  
Simulation Model ◽  
Kinetic Parameters ◽  
Cellular Membrane ◽  
Surface Absorption ◽  
Fast Absorption ◽  
Passive Adsorption ◽  
Two Stages ◽  
The Mathematical Model

In this work the microalgae Pseudokirchneriella supcapitata was used for the removal of the cadmium in liquids. The accumulations of metal ions by the alga occur in two stages: a very fast absorption (passive adsorption) proceeded by a slower absorption (activate absorption). A mathematical model based on the surface absorption and on the transport into the interior of the cellular membrane was developed. The simulation model kinetic parameters were experimentally obtained. Through the results observed, the mathematical model was shown to be suitable when compared to the experimental results, confirming the validation of the mathematical model.

Development and automation of algorithm for determining basis of nonlinear parameter functions of kinetic constants

2019 ◽  
Vol 19 (4) ◽  
pp. 252-257
Author(s):  
A. S. Ismagilova ◽  
Z. A. Khamidullina ◽  
S. I. Spivak
Keyword(s):  
Mathematical Model ◽  
Kinetic Parameters ◽  
Platinum Catalyst ◽  
Hydrogen Oxidation ◽  
Nonlinear Parameter ◽  
Kinetic Constants ◽  
Model Parameters ◽  
Functional Relations ◽  
The Mathematical Model ◽  
Theoretical Issues

Mathematical modeling of catalytic processes is necessary for the complete and accurate description, as well as for controlling the quality and physicochemical studied of catalysts. In the paper, theoretical issues of industrial catalysis are discussed. The work is devoted to theoretical graph analysis of informativity of kinetic parameters of the model of a complex chemical reaction. The aim is the development and automation of algorithm for determining basis of nonlinear parameter functions in solving inverse problems of chemical kinetics in order to define the number and form of independent combinations of rate constants of elementary stages. A program package for analysis of informativity of kinetic parameters of the mathematical model of a complex catalytic reaction is developed and described. The obtained functional relations between the kinetic parameters can be useful for experimentalists in physicochemical interpretation and analysis of mechanisms of chemical reactions. In other words, the proposed method allows independent combinations of kinetic constants to be distinguished that results in shortening the number of the model parameters and, as a consequence, enhance the accuracy of the mathematical model. The mechanism of hydrogen oxidation over a platinum catalyst is given as an example of the use of the software.

scholarly journals Antihyperurisemic Activity of Aqueous Celery Infusion by Xanthine Oxidase Enzyme Inhibition

2018 ◽  
Vol 23 (3) ◽  
pp. 131 ◽  
Author(s):  
Atiqoh Zummah ◽  
Rahma Diyan Martha
Keyword(s):  
Uric Acid ◽  
Xanthine Oxidase ◽  
Uv Spectrophotometry ◽  
Inhibition Activity ◽  
Acid Product ◽  
Inhibitory Ability ◽  
Water Infusion ◽  
High Prevalence ◽  
The World ◽  
Oxidase Enzyme

Hyperuricemia is a metabolic disorder because of excessive uric acid production. The high prevalence of hyperuresemia in the world, especially in Indonesia makes the research of antihyperurisemia drugs very needed today. The purpose of this study was to determine the activity of water infusion extract from celery stems and leaves to inhibited xanthine oxidase enzyme. Xanthine oxidase enzyme plays a role in change of hypoxanthine to xanthine and then becomes uric acid. The activity of xanthine oxidase enzyme was determined by UV spectrophotometry method and using xanthine substrate. Absorption at 290 nm indicates the presence of a uric acid product from xanthine oxidation by the xanthine oxidase enzyme. Infused extract which has the smallest absorption at 290 nm showed a better inhibitory ability of the xanthine oxidase enzyme because the change of xanthine substrate to uric acid is inhibited. The result showed the celery stems water infusion extract had better inhibition activity than celery leaves water infusion extract. The best inhibition percentage of celery stems water infusion was 90,25%, while the celery leaves water infusion was 69.07% both of at 20% concentration. The type inhibition of celery stems water infusion extract to xanthine oxidase enzyme showed an uncompetitive inhibition type because showed change in Km and Vmax values. Km and Vmax values before the addition of water infusion of celery stems were 104.33 ppm and 3.83 U/mL respectively changed to 74.49 ppm and 2.69 U/mL after the addition of extract.

scholarly journals Mathematical Model, Simulation and Scale up of Batch Reactor Used in Oxidative Desulfurization of Kerosene

2021 ◽  
Vol 22 (3) ◽  
pp. 11-17
Author(s):  
Ghazwan Ahmed ◽  
Jasim Humadi ◽  
Ahmad Aabid
Keyword(s):  
Mathematical Model ◽  
Kinetic Parameters ◽  
Batch Reactor ◽  
Scale Up ◽  
Oxidative Desulfurization ◽  
Reaction Conditions ◽  
Exponential Factor ◽  
Simulation And Optimization ◽  
The Mathematical Model ◽  
Optimal Reaction

In this paper, a mathematical model for the oxidative desulfurization of kerosene had been developed. The mathematical model and simulation process is a very important process due to it provides a better understanding of a real process. The mathematical model in this study was based on experimental results which were taken from literature to calculate the optimal kinetic parameters where simulation and optimization were conducted using gPROMS software. The optimal kinetic parameters were Activation energy 18.63958 kJ/mol, Pre-exponential factor 2201.34 (wt)-0.76636. min-1 and the reaction order 1.76636. These optimal kinetic parameters were used to find the optimal reaction conditions which used to obtain a high conversion (≥ 99%). These optimal reaction conditions were reaction temperature 379.4 oK and reaction time 160 min. A scale up to batch reactor was conducted using these optimal kinetic parameters and optimal reaction conditions and the results showed the best reactor size that can be used at a diameter of 1.2 m.

DETERMINATION OF PERFORMANCE INDICATORS OF THE TRUCK KrAZ-6510TE

2020 ◽  
pp. 19-26
Author(s):  
Olexandr Pavlenko ◽  
Serhii Dun ◽  
Maksym Skliar
Keyword(s):  
Mathematical Model ◽  
Surface Friction ◽  
Building Structures ◽  
Maximum Torque ◽  
Military Equipment ◽  
Military Vehicles ◽  
Force Magnitude ◽  
Vehicle Mobility ◽  
The Mathematical Model

In any economy there is a need for the bulky goods transportation which cannot be divided into smaller parts. Such cargoes include building structures, elements of industrial equipment, tracked or wheeled construction and agricultural machinery, heavy armored military vehicles. In any case, tractor-semitrailer should provide fast delivery of goods with minimal fuel consumption. In order to guarantee the goods delivery, tractor-semitrailers must be able to overcome the existing roads broken grade and be capable to tow a semi-trailer in off-road conditions. These properties are especially important for military equipment transportation. The important factor that determines a tractor-semitrailer mobility is its gradeability. The purpose of this work is to improve a tractor-semitrailer mobility with tractor units manufactured at PJSC “AutoKrAZ” by increasing the tractor-semitrailer gradeability. The customer requirements for a new tractor are determined by the maximizing the grade to 18°. The analysis of the characteristics of modern tractor-semitrailers for heavy haulage has shown that the highest rate of this grade is 16.7°. The factors determining the limiting gradeability value were analyzed, based on the tractor-semitrailer with a KrAZ-6510TE tractor and a semi-trailer with a full weight of 80 t. It has been developed a mathematical model to investigate the tractor and semi-trailer axles vertical reactions distribution on the tractor-semitrailer friction performances. The mathematical model has allowed to calculate the gradeability value that the tractor-semitrailer can overcome in case of wheels and road surface friction value and the tractive force magnitude from the engine. The mathematical model adequacy was confirmed by comparing the calculations results with the data of factory tests. The analysis showed that on a dry road the KrAZ-6510TE tractor with a 80 t gross weight semitrailer is capable to climb a gradient of 14,35 ° with its coupling mass full use condition. The engine's maximum torque allows the tractor-semitrailer to overcome a gradient of 10.45° It has been determined the ways to improve the design of the KrAZ-6510TE tractor to increase its gradeability. Keywords: tractor, tractor-semitrailer vehicle mobility, tractor-semitrailer vehicle gradeability.

EXPERIMENTAL STUDIES OF CAR PROPERTIES ON A PHYSICAL MODEL

2019 ◽  
pp. 10-16
Author(s):  
Oleksii Timkov ◽  
Dmytro Yashchenko ◽  
Volodymyr Bosenko
Keyword(s):  
Mathematical Model ◽  
Remote Control ◽  
Physical Model ◽  
Model Experiment ◽  
Experimental Studies ◽  
Electrical Energy ◽  
Short Term ◽  
Motor Current ◽  
Memory Card ◽  
The Mathematical Model

The article deals with the development of a physical model of a car equipped with measuring, recording and remote control equipment for experimental study of car properties. A detailed description of the design of the physical model and of the electronic modules used is given, links to application libraries and the code of the first part of the program for remote control of the model are given. Atmega microcontroller on the Arduino Uno platform was used to manage the model and register the parameters. When moving the car on the memory card saved such parameters as speed, voltage on the motor, current on the motor, the angle of the steered wheel, acceleration along three coordinate axes are recorded. Use of more powerful microcontrollers will allow to expand the list of the registered parameters of movement of the car. It is possible to measure the forces acting on the elements of the car and other parameters. In the future, it is planned to develop a mathematical model of motion of the car and check its adequacy in conducting experimental studies on maneuverability on the physical model. In addition, it is possible to conduct studies of stability and consumption of electrical energy. The physical model allows to quickly change geometric dimensions and mass parameters. In the study of highway trains, this approach will allow to investigate the various layout schemes of highway trains in the short term. It is possible to make two-axle road trains and saddle towed trains, three-way hitched trains of different layout. The results obtained will allow us to improve not only the mathematical model, but also the experimental physical model, and move on to further study the properties of hybrid road trains with an active trailer link. This approach allows to reduce material and time costs when researching the properties of cars and road trains. Keywords: car, physical model, experiment, road trains, sensor, remote control, maneuverability, stability.

RESEARCH OF INDICATORS OF A VEHICLE WITH A DIESEL WORKING ON DIESEL AND DIESEL GAS CYCLES USING THE MATHEMATICAL MODEL

2020 ◽  
pp. 14-19
Author(s):  
Serhii Kovbasenko ◽  
Andriy Holyk ◽  
Serhii Hutarevych
Keyword(s):  
Mathematical Model ◽  
Diesel Engine ◽  
Environmental Performance ◽  
Energy Performance ◽  
Dual Fuel ◽  
Fuel System ◽  
Compressed Natural Gas ◽  
Diesel Vehicles ◽  
Diesel Cycle ◽  
The Mathematical Model

The features of an advanced mathematical model of motion of a truck with a diesel engine operating on the diesel and diesel gas cycles are presented in the article. As a result of calculations using the mathematical model, a decrease in total mass emissions as a result of carbon monoxide emissions is observed due to a decrease in emissions of nitrogen oxides and emissions of soot in the diesel gas cycle compared to the diesel cycle. The mathematical model of a motion of a truck on a city driving cycle according to GOST 20306-90 allows to study the fuel-economic, environmental and energy indicators of a diesel and diesel gas vehicle. The results of the calculations on the mathematical model will make it possible to conclude on the feasibility of converting diesel vehicles to using compressed natural gas. Object of the study – the fuel-economic, environmental and energy performance diesel engine that runs on dual fuel system using CNG. Purpose of the study – study of changes in fuel, economic, environmental and energy performance of vehicles with diesel engines operating on diesel and diesel gas cycles, according to urban driving cycle modes. Method of the study – calculations on a mathematical model and comparison of results with road tests. Bench and road tests, results of calculations on the mathematical model of motion of a truck with diesel, working on diesel and diesel gas cycles, show the improvement of environmental performance of diesel vehicles during the converting to compressed natural gas in operation. Improvement of environmental performance is obtained mainly through the reduction of soot emissions and nitrogen oxides emissions from diesel gas cycle operations compared to diesel cycle operations. The results of the article can be used to further develop dual fuel system using CNG. Keywords: diesel engine, diesel gas engine, CNG

Glycemia monitoring

1998 ◽  
Vol 2 ◽  
pp. 23-30
Author(s):  
Igor Basov ◽  
Donatas Švitra
Keyword(s):  
Diabetes Mellitus ◽  
Mathematical Model ◽  
Numerical Methods ◽  
Differential Equations ◽  
Blood Sugar ◽  
Self Regulation ◽  
Physiological System ◽  
Non Linear ◽  
The Mathematical Model

Here a system of two non-linear difference-differential equations, which is mathematical model of self-regulation of the sugar level in blood, is investigated. The analysis carried out by qualitative and numerical methods allows us to conclude that the mathematical model explains the functioning of the physiological system "insulin-blood sugar" in both normal and pathological cases, i.e. diabetes mellitus and hyperinsulinism.

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