scholarly journals Mathematical Modeling of Flow and Diffusion in the Lens of the Eye

2021 ◽  
pp. 32-40
Author(s):  
Deependra Nigam ◽  
Rajesh Kumar Pal ◽  
Pradeep Kothiyal ◽  
Manoj Kumar Jadoun
Keyword(s):  
Partial Pressure ◽  
Oxygen Diffusion ◽  
Kinetic Constant ◽  
Iteration Scheme ◽  
Model Parameters ◽  
Partial Pressure Of Oxygen ◽  
Therapeutic Procedures ◽  
Quantitative Understanding ◽  
Prime Objective ◽  
And Diffusion

The present work is concerned with the development of a simple transient mathematical model for the oxygen diffusion-consumption in the eye lens. The model takes into account the transport of oxygen by diffusion and consumption of oxygen is assumed to follow the Michaelis- Menten’s kinetics. The partial differential equation governing the partial pressure of oxygen has been solved by using implicit Crank-Nicholson’s iteration scheme. The prime objective of the present study is to investigate the effect of model parameters: the Michaelis- Menten’s kinetic constant and maximum rate of consumption on the partial pressure of oxygen in the mammalian lens. The computational results of the model have been presented by graphs and effects of model parameters also have been shown through the graphs and discussed. The present mathematical analysis of oxygen diffusion in the lens may contribute to the knowledge of regulation of tissue oxygen in the lens and quantitative understanding achieved through the analysis may facilitate the design of new therapeutic procedures. This analysis may help in regulating the partial pressure of oxygen in the lens.

Thermal Expansion, Oxygen Non-Stoichiometry and Diffusion Mobility in some Ferrites-Nickelites

2013 ◽  
Vol 200 ◽  
pp. 86-92 ◽  
Author(s):  
Vladimir Vashook ◽  
Jean Rebello ◽  
J.Y. Chen ◽  
Leonid Vasylechko ◽  
Dmytro Trots ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electrical Conductivity ◽  
Thermal Expansion ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Diffusion ◽  
Oxygen Exchange ◽  
Diffusion Mobility ◽  
Diffusion Characteristics ◽  
And Diffusion

Crystal structure,thermal expansion, oxygen non-stoichiometry, electrical conductivity and diffusion characteristics of two analogous LaFe0.7Ni0.3O3‑d and PrFe0.7Ni0.3O3‑d compositions were investigated depending on temperature (201000 °C) and oxygen partial pressure (0.6–21000 Pa). The found oxygen diffusion and oxygen exchange coefficients for the both compositions at similar conditions are near to each other and varied in the range of 110‑7110‑5 cm2s‑1 and 510‑6110‑4 cms‑1, respectively.

Interaction of H2O, O2 and H2 with Proton Conducting Oxides Based on Lanthanum Scandates

2019 ◽  
pp. 88-100
Author(s):  
A. S. Farlenkov ◽  
N. A. Zhuravlev ◽  
Т. A. Denisova ◽  
М. V. Ananyev
Keyword(s):  
Water Vapor ◽  
Partial Pressure ◽  
Gas Phase ◽  
Molecular Hydrogen ◽  
Proton Magnetic Resonance ◽  
Partial Pressure Of Oxygen ◽  
Proton Conducting ◽  
Conducting Oxides ◽  
Temperature Range ◽  
Apparent Level

The research uses the method of high-temperature thermogravimetric analysis to study the processes of interaction of the gas phase in the temperature range 300–950 °C in the partial pressure ranges of oxygen 8.1–50.7 kPa, water 6.1–24.3 kPa and hydrogen 4.1 kPa with La1–xSrxScO3–α oxides (x = 0; 0.04; 0.09). In the case of an increase in the partial pressure of water vapor at a constant partial pressure of oxygen (or hydrogen) in the gas phase, the apparent level of saturation of protons is shown to increase. An increase in the apparent level of saturation of protons of the sample also occurs with an increase in the partial pressure of oxygen at a constant partial pressure of water vapor in the gas phase. The paper discusses the causes of the observed processes. The research uses the hydrogen isotope exchange method with the equilibration of the isotope composition of the gas phase to study the incorporation of hydrogen into the structure of proton-conducting oxides based on strontium-doped lanthanum scandates. The concentrations of protons and deuterons were determined in the temperature range of 300–800 °C and a hydrogen pressure of 0.2 kPa for La0.91Sr0.09ScO3–α oxide. The paper discusses the role of oxygen vacancies in the process of incorporation of protons and deuterons from the atmosphere of molecular hydrogen into the structure of the proton conducting oxides La1–xSrxScO3–α (x = 0; 0.04; 0.09). The proton magnetic resonance method was used to study the local structure in the temperature range 23–110 °C at a rotation speed of 10 kHz (MAS) for La0.96Sr0.04ScO3–α oxide after thermogravimetric measurements in an atmosphere containing water vapor, and after exposures in molecular hydrogen atmosphere. The existence of proton defects incorporated into the volume of the investigated proton oxide from both the atmosphere containing water and the atmosphere containing molecular hydrogen is unambiguously shown. The paper considers the effect of the contributions of the volume and surface of La0.96Sr0.04ScO3–α oxide on the shape of the proton magnetic resonance spectra.

Biorhythm of the partial pressure of oxygen in uterine and fetal tissues

1981 ◽  
Vol 92 (4) ◽  
pp. 1305-1307
Author(s):  
A. Ya. Chizhov ◽  
V. G. Filimonov ◽  
Yu. M. Karash ◽  
R. B. Strelkov
Keyword(s):  
Partial Pressure ◽  
Partial Pressure Of Oxygen ◽  
Fetal Tissues

Singlet oxygen feedback delayed fluorescence of protoporphyrin IX in organic solutions

2017 ◽  
Vol 16 (4) ◽  
pp. 507-518 ◽  
Author(s):  
Ivo S. Vinklárek ◽  
Marek Scholz ◽  
Roman Dědic ◽  
Jan Hála
Keyword(s):  
Partial Pressure ◽  
Singlet Oxygen ◽  
Protoporphyrin Ix ◽  
Clinical Applications ◽  
Delayed Fluorescence ◽  
Diagnostic Tools ◽  
Partial Pressure Of Oxygen ◽  
High Concentrations ◽  
Organic Solutions

The PpIX DF show the significant role of SOFDF mechanism at high concentrations and at atmospheric partial pressure of oxygen and should be considered when developing diagnostic tools for clinical applications.

Oxygen Poisoning in a Hyperbaric Environment

1970 ◽  
Vol 56 (1) ◽  
pp. 39-47
Author(s):  
J. Murray Young
Keyword(s):  
Partial Pressure ◽  
Sea Water ◽  
Signs And Symptoms ◽  
Pressure Chamber ◽  
Partial Pressure Of Oxygen ◽  
Oxygen Exposure ◽  
Rapid Decompression ◽  
Hyperbaric Environment ◽  
Biochemical Mechanisms ◽  
Oxygen Poisoning

AbstractThe biochemical mechanisms of oxygen poisoning are discussed together with the signs and symptoms produced clinically. Investigation of 35 subjects performing work (mean 02 consumption 1.4 l./min) for 40 minutes in a pressure chamber at simulated depths of 20 to 47 feet of sea water showed that this degree of exercise markedly reduced the oxygen exposure tolerance of the subjects. This investigation also showed that rapid decompression of subjects breathing oxygen can produce an exacerbation of existing symptoms and these results are discussed.It is stressed that any breathing mixture containing a partial pressure of oxygen in excess of 150 torr constitutes an environment which is hyperbaric with respect to oxygen and caution is advised in the administration of oxygen to any patient.

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