scholarly journals Oxygen transport and release of adenosine triphosphate in micro-channels

Author(s):  
Terry Moschandreou

The governing nonlinear steady equations for oxygen transport in a microfluidic channel are solved analytically. The Lagrange inversion theorem is used which admits complete integrable solutions in the channel. Considering a cell-rich and cell free region with RBCs and blood plasma, we obtain results showing clearly that there is a significant decrease in oxygen tension in the vicinity of an oxygen permeable membrane placed on the upper channel/tube wall and to the right side of it in the downstream field. The purpose of the membrane is to cause a rapid change in oxygen saturation as RBC’s flow through channel/tube. To the right of the membrane downstream the greatest amount of ATP is released. The method of solution is compared to numerical results. The analytical results obtained could prove useful for the corresponding time dependent problem in future studies.

2015 ◽  
Author(s):  
Terry Moschandreou

The governing nonlinear steady equations for oxygen transport in a microfluidic channel are solved analytically. The Lagrange inversion theorem is used which admits complete integrable solutions in the channel. Considering a cell-rich and cell free region with RBCs and blood plasma, we obtain results showing clearly that there is a significant decrease in oxygen tension in the vicinity of an oxygen permeable membrane placed on the upper channel/tube wall and to the right side of it in the downstream field. The purpose of the membrane is to cause a rapid change in oxygen saturation as RBC’s flow through channel/tube. To the right of the membrane downstream the greatest amount of ATP is released. The method of solution is compared to numerical results. The analytical results obtained could prove useful for the corresponding time dependent problem in future studies.


2014 ◽  
Author(s):  
Terry Moschandreou

The governing nonlinear equations for oxygen transport and ATP concentration in a microfluidic channel and tube are solved with the aid of Maple and COMSOL Multiphysics simulation software. Considering a cell-rich and cell free region with RBCs and blood plasma, we obtain results showing clearly that there is a significant decrease in oxygen tension in the vicinity of an oxygen permeable membrane placed midway on the upper channel/tube wall and to the right side of it in the downstream field. The purpose of the membrane is to cause a rapid change in oxygen saturation as RBC’s flow through channel/tube. To the right of the membrane downstream the greatest amount of ATP is released. Finally the corresponding time-dependent oxygen transport problem for plug flow in a channel, which has not been simulated in previous models in the literature, is analyzed and different starting times are shown for ATP release at different points in the channel. The FE modelling is very accurate: The time evolution problem is modelled and solved in it`s entirety with exact parameters used in the literature for blood flow and oxygen transport in the microcirculation. A comparison is made between the steady state and time dependent solutions in order to validate the results. The implications of the time dependent model for biological systems such as the human microcirculation requires exact information on release of energy as ATP is released from blood cells and the present work is important in providing this information.


2014 ◽  
Author(s):  
Terry Moschandreou

The governing nonlinear equations for oxygen transport and ATP concentration in a microfluidic channel and tube are solved with the aid of Maple and COMSOL Multiphysics simulation software. Considering a cell-rich and cell free region with RBCs and blood plasma, we obtain results showing clearly that there is a significant decrease in oxygen tension in the vicinity of an oxygen permeable membrane placed midway on the upper channel/tube wall and to the right side of it in the downstream field. The purpose of the membrane is to cause a rapid change in oxygen saturation as RBC’s flow through channel/tube. To the right of the membrane downstream the greatest amount of ATP is released. Finally the corresponding time-dependent oxygen transport problem for plug flow in a channel, which has not been simulated in previous models in the literature, is analyzed and different starting times are shown for ATP release at different points in the channel. The FE modelling is very accurate: The time evolution problem is modelled and solved in it`s entirety with exact parameters used in the literature for blood flow and oxygen transport in the microcirculation. A comparison is made between the steady state and time dependent solutions in order to validate the results. The implications of the time dependent model for biological systems such as the human microcirculation requires exact information on release of energy as ATP is released from blood cells and the present work is important in providing this information.


2014 ◽  
Author(s):  
Terry Moschandreou

The governing nonlinear equations for oxygen transport and ATP concentration in a microfluidic channel and tube are solved in a novel way with the aid of Maple and COMSOL Multiphysics simulation software. Considering a model which assumes a larger plasma velocity near the wall of a channel/tube in comparison to RBC velocity near the centerline we obtain results showing clearly that there is a significant decrease in oxygen tension in the vicinity of an oxygen permeable membrane placed midway on the upper channel/tube wall and to the right side of it in the downstream field. The purpose of the membrane is to cause a rapid change in oxygen saturation as RBC’s flow through channel/tube. To the right of the membrane downstream the greatest amount of ATP is released. It is shown that for smaller arterioles there is an optimal size for which greater amounts of ATP can be released. Finally the corresponding time-dependent oxygen transport problem for plug flow in a channel, which has not been simulated in previous models in the literature, is analyzed and different starting times are shown for ATP release at different points in the channel. The FE modelling is very accurate: The time evolution problem is modelled and solved in it`s entirety with exact parameters used in the literature for blood flow and oxygen transport in the microcirculation. A comparison is made between the steady state and time dependent solutions in order to validate the results. The implications of the time dependent model for biological systems such as the human microcirculation requires exact information on release of energy as ATP is released from blood cells and the present work is important in providing this information. In particular, the time varying problem for ATP concentration and it’s temporal dynamics, as calculated in this paper is crucial in determining the ADP/ATP concentration pair which is an oscillating pair in the biochemical oscillations that occur in glycolysis in anaerobic yeast cultures.


2014 ◽  
Author(s):  
Terry Moschandreou

The governing nonlinear equations for oxygen transport and ATP concentration in a microfluidic channel and tube are solved in a novel way with the aid of Maple and COMSOL Multiphysics simulation software. Considering a model which assumes a larger plasma velocity near the wall of a channel/tube in comparison to RBC velocity near the centerline we obtain results showing clearly that there is a significant decrease in oxygen tension in the vicinity of an oxygen permeable membrane placed midway on the upper channel/tube wall and to the right side of it in the downstream field. The purpose of the membrane is to cause a rapid change in oxygen saturation as RBC’s flow through channel/tube. To the right of the membrane downstream the greatest amount of ATP is released. It is shown that for smaller arterioles there is an optimal size for which greater amounts of ATP can be released. Finally the corresponding time-dependent oxygen transport problem for plug flow in a channel, which has not been simulated in previous models in the literature, is analyzed and different starting times are shown for ATP release at different points in the channel. The FE modelling is very accurate: The time evolution problem is modelled and solved in it`s entirety with exact parameters used in the literature for blood flow and oxygen transport in the microcirculation. A comparison is made between the steady state and time dependent solutions in order to validate the results. The implications of the time dependent model for biological systems such as the human microcirculation requires exact information on release of energy as ATP is released from blood cells and the present work is important in providing this information. In particular, the time varying problem for ATP concentration and it’s temporal dynamics, as calculated in this paper is crucial in determining the ADP/ATP concentration pair which is an oscillating pair in the biochemical oscillations that occur in glycolysis in anaerobic yeast cultures.


Mathematics ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 910
Author(s):  
Andrey Kovtanyuk ◽  
Alexander Chebotarev ◽  
Varvara Turova ◽  
Irina Sidorenko ◽  
Renée Lampe

An inverse problem for a system of equations modeling oxygen transport in the brain is studied. The problem consists of finding the right-hand side of the equation for the blood oxygen transport, which is a linear combination of given functionals describing the average oxygen concentration in the neighborhoods of the ends of arterioles and venules. The overdetermination condition is determined by the values of these functionals evaluated on the solution. The unique solvability of the problem is proven without any smallness assumptions on the model parameters.


1971 ◽  
Vol 18 (4) ◽  
pp. 621-637 ◽  
Author(s):  
Adolf Holl ◽  
Hyacinthe Crépin

Following Vatican II changes are rapidly taking place within Dutch Catholicism — the bishops no longer make decisions in an authoritarian way: religious practice is de clining ; priests and religious are decreasing in numbers and many religious and pastoral experiments have come into being. KASKI has the responsibility of keeping pace with the Church during this process of change. In order to do this it makes use of several modes of work — the production of statistics relating to the position of religion in Society, the planning of religious and pastoral institutions and the study of new forms of the religious life in orders and congregations. For the first task it has used the same instruments for twenty- five years and the censuses thus produced yield valuable infor mation. As far as pastoral planning is concerned, it works in the field, playing the role of catalyst for those who have to make decisions and the people who have to carry out these decisions. This was the case, for instance, in the pastoral planning of the town of Eindhoven. Finally, when dealing with the new forms of communal religious life it adopts the method of studying through participation so that two of its researchers working in this sector are themselves members of religious groups. Applied research poses important problems, both from the methodological and from the political points of view. Amongst them may be noted the difficulty of determining precisely what constitutes rapid change in religious life, and the political choice of the persons for whom the research is being con ducted; the latter inevitably imposes a certain degree of conformity upon the perspectives of the work. (For example, the choice of the Dutch hierarchy which was to follow the general lines given by a large majority of Catholic opinion when it was tested particularly on questions like the liturgical and parochial changes). The fact, also, that the director of KASKI himself has a personal commitment to what may be described as the « right of centre » position in Dutch Catho licism poses problems for the work of the Institute. Political and religious radicalism is not a strong characteristic of the more senior research workers. KASKI is a rare example of a centre which brings socio logists together and uses their professional competence to accompany change in religious institutions.


2019 ◽  
Vol 72 (8) ◽  
pp. 595 ◽  
Author(s):  
Georgina K. Such ◽  
Angus P. R. Johnston

Nanoparticle delivery systems have significant potential to facilitate the delivery of novel therapeutics, such as proteins, DNA or small molecules. However, there are multiple biological barriers that need to be overcome to deliver the cargo in an active form. These challenges include evading clearance by the reticuloendothelial system, minimising adverse immune responses, targeting specific cells and tissues, and trafficking into the right compartment of the cell. In this account, we will discuss how nanoparticle structure can be tuned to optimise biological interactions and thus improve the ability of nanoparticles to overcome these barriers. The focus of this article will be on controlling cell targeting and trafficking within a cell, e.g. endosomal escape.


2016 ◽  
Vol 2016 (CICMT) ◽  
pp. 000085-000088
Author(s):  
Achraf Ben Amar ◽  
Houssem Eddine Amor ◽  
Hung Cao ◽  
Ammar B. Kouki

Abstract Low temperature co-fired ceramic (LTCC) based microfluidic sensors have been developed for biomedical and environmental sensing systems. This paper introduces a microfluidic chamber based on impedance spectroscopy measurements using LTCC technology for wireless Lab-On-A-Chip (LOC) applications. To overcome the channel sagging during the fabrication process, we used sacrificial carbon tapes as solid inserts, thus guiding the LTCC to follow their shape upon lamination and then formed micro-channels. The measurement chamber was a parallel-plate capacitive structure with 85 μm gap. This platform requires a small fluid sample of less than 4 μL. The sensor formed by the microfluidic channel and capacitance structure was characterized using different dielectric materials such as air, water and acetone. We hereby present the capability of LTCC-based systems in fluid identification by detecting their electrical permittivity using capacitance measurement.


2014 ◽  
Vol 369 (1646) ◽  
pp. 20130451 ◽  
Author(s):  
Ian J. Holt ◽  
Dave Speijer ◽  
Thomas B. L. Kirkwood

Mitochondria constitute the major energy-producing compartment of the eukaryotic cell. These organelles contain many molecules of DNA that contribute only a handful of proteins required for energy production. Mutations in the DNA of mitochondria were identified as a cause of human disease a quarter of a century ago, and they have subsequently been implicated in ageing. The process whereby deleterious variants come to dominate a cell, tissue or human is the subject of debate. It is likely to involve multiple, often competing, factors, as selection pressures on mitochondrial DNA can be both indirect and intermittent, and are subjected to rapid change. Here, we assess the different models and the prospects for preventing the accumulation of deleterious mitochondrial DNA variants with time.


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