Concentration profiles in and around capillaries

1960 ◽  
Vol 198 (5) ◽  
pp. 991-998 ◽  
Author(s):  
Jacob J. Blum
Keyword(s):  
Constant Velocity ◽  
Zero Order ◽  
Surrounding Tissue ◽  
Concentration Profiles ◽  
Steady State Concentration ◽  
Longitudinal Diffusion ◽  
First Order ◽  
Blood Flows ◽  
First Order Kinetics ◽  
State Concentration

Capillaries, idealized as uniform cylinders through which blood flows at a constant velocity, supply substrate to the surrounding tissue, where it is consumed according to zero order or first order kinetics. Equations are developed which permit the calculation of the steady state concentration of substrate at any point inside the capillary or the tissue. The effects of finite membrane permeability and of longitudinal diffusion in the tissue are discussed. Computations are presented to show the effects of various biological parameters on the concentration profiles.

scholarly journals An Updated Review on Biological Half-Life & Volume of Distribution

2018 ◽  
Vol III (I) ◽  
pp. 19-26
Author(s):  
Rana Muhammad Awais Khan ◽  
Umair-ul Hassan ◽  
Shafiq-ur Rehman ◽  
Nayab Tahir
Keyword(s):  
Half Life ◽  
Pharmacological Action ◽  
Volume Of Distribution ◽  
Zero Order ◽  
The Body ◽  
Placental Barrier ◽  
First Order ◽  
First Order Kinetics ◽  
Biological Half Life ◽  
State Concentration

Biological half-life and volume of distribution of the drug are the key parameters in understanding the pharmacokinetics of the drugs within the body as they affect all the pharmacokinetic processes including absorption, distribution, metabolism and elimination of drugs and also associated with each other, ultimately effecting the Pharmacological action of the drug on its target site. Given study elaborates the various aspects of half-life, i.e., Alpha & beta half-lives, the contribution of Zero-order and first-order kinetics in ADME and interrelation among the volume of distribution & half-life along with the distribution & redistribution of the drug within the body. Moreover, the importance of half-life & Vd and the idea of Steady-state concentration is also discussed. Various types of physiological barriers, including the blood-brain barrier, placental barrier, blood-CSF barrier, affect the distribution of drugs.

Ag nanoparticles stabilized on cubic polyhedral oligomeric silsesquioxane cross-linked poly(N-isopropyl acrylamide-co-itaconic acid): An efficient catalyst for 4-nitrophenol reduction

2020 ◽  
Vol 13 (07) ◽  
pp. 2051040
Author(s):  
Vahid Rahimkhoei ◽  
Ali Akbari ◽  
Maryam Zirak ◽  
Bagher Eftekhari-Sis
Keyword(s):  
Itaconic Acid ◽  
Ag Nanoparticles ◽  
Zero Order ◽  
Polymeric Support ◽  
Efficient Catalyst ◽  
First Order ◽  
First Order Kinetics ◽  
Isopropyl Acrylamide ◽  
Nitrophenol Reduction ◽  
Oligomeric Silsesquioxane

Ag nanoparticles were synthesized and stabilized on a polymeric support, poly([Formula: see text]-isopropyl acrylamide-co-itaconic acid)/POSS, by simply reducing Ag[Formula: see text] ions adsorbed in the interior of the polymeric network. The prepared Ag@p(NIPAM-IA)/POSS was used as an efficient and recyclable catalyst for removal of the 4-nitrophenol (4-NP) contaminant by NaBH4-induced reduction to 4-aminophenol (4-AP) in aqueous solution. Different conditions including Ag content and amount of the nanocomposite, and also temperature of the 4-NP reduction were investigated. Also, two kinetic models, zero-order and first-order kinetics, were studied for the reduction of 4-NP to 4-AP.

Kinetics and mechanism of the osmium-tetroxide-catalysed oxidation of mandelate ion by hexacyanoferrate(III) ion

1968 ◽  
Vol 21 (12) ◽  
pp. 2913 ◽  
Author(s):  
NP Singh ◽  
VN Singh ◽  
MP Singh
Keyword(s):  
Benzoic Acid ◽  
Oxidation Product ◽  
Osmium Tetroxide ◽  
Reaction Rate ◽  
Zero Order ◽  
Ion Concentration ◽  
First Order ◽  
First Order Kinetics ◽  
Catalysed Oxidation ◽  
Hydroxyl Ion

The osmium-tetroxide-catalysed oxidation of mandelate ion by hexacyanoferrate(111) ion has been studied kinetically. The reaction rate has been found to be independent of hexacyanoferrate(111) ion while the order with respect to both osmium tetroxide and mandelate ion comes out to be unity. The reaction rate follows first-order kinetics at low hydroxyl ion concentration and becomes zero order at higher concentrations. The course of the reaction has been considered to proceed through the formation of an activated mandelate-OsO4, complex which decomposes in alkaline medium giving reduced osmium(V1) followed by a fast oxidation by hexacyanoferrate(111) ion. The probable course of the reactions is also described with the help of its oxidation product, benzoic acid.

Parameters Effect on Photocatalytic Reduction Kinetics of Bromate in Aqueous Dispersion of TiO2

2013 ◽  
Vol 779-780 ◽  
pp. 1658-1665
Author(s):  
Rong Shu Zhu ◽  
Fei Tian ◽  
Ling Ling Zhang ◽  
Ling Min Yu
Keyword(s):  
Aqueous Dispersion ◽  
Zero Order ◽  
Photocatalytic Reduction ◽  
Reduction Kinetics ◽  
First Order ◽  
First Order Kinetics ◽  
Zero Order Kinetics ◽  
Experimental Parameters ◽  
Pseudo First Order ◽  
Kinetics Of

This paper studied the photocatalytic reduction kinetics of bromate in aqueous dispersion of TiO2 and investigated the effects of experimental parameters, including initial concentration of BrO3-, pH, TiO2 dosage, anion and cation. The results indicate that the process of photocatalytic reduction of bromate follows a zero-order kinetics. In all the investigated experimental parameters, the initial bromate concentration, pH and anion have great effect on the photocatalytic reduction kinetics. The processes of photocatalytic reduction of bromate show the pseudo first-order kinetics at initial bromate concentration of 0.39 μmolL-1, pH=5.0, or in presence of HCO3-/CO32-, NO3-, SO42-, respectively.

Use of purified lyophilized human lactate dehydrogenase isoenzymes in a study of the measurement of lactate dehydrogenase activity.

1986 ◽  
Vol 32 (5) ◽  
pp. 758-762 ◽  
Author(s):  
D A Smith ◽  
G C Moses ◽  
A R Henderson
Keyword(s):  
Lactate Dehydrogenase ◽  
Zero Order ◽  
Lactate Dehydrogenase Activity ◽  
First Order ◽  
First Order Kinetics ◽  
Activity Concentrations ◽  
Zero Order Kinetics ◽  
Specific Activities ◽  
The Stability ◽  
Lactate Dehydrogenase Isoenzymes

Abstract We examined the stability of human lactate dehydrogenase (EC 1.1.1.27; LD) isoenzymes 1, 2, and 3--purified to specific activities of about 200 kU/g--when lyophilized in a buffered stabilized matrix of bovine albumin. Each isoenzyme was prepared at two activity concentrations and stored at -20, 4, 20, 37, and 56 degrees C for as long as six months. LD-1 activity decayed with zero-order kinetics, LD-2 and LD-3 with first-order kinetics. The extrapolated half-lives of these preparations at -20 degrees C varied between 80 and 530 years. Stability of reconstituted samples stored at 4 degrees C was excellent for LD-1 but poor for LD-2 and LD-3. We suggest that preparations of human LD-1 be further investigated as a possible reference material.

scholarly journals On incorporating diffusion and viscosity concepts into compartmental models for analysing faecal marker excretion patterns in ruminants

1993 ◽  
Vol 70 (1) ◽  
pp. 369-378 ◽  
Author(s):  
J. France ◽  
J. H. M. Thornley ◽  
R. C. Siddons ◽  
M. S. Dhanoa
Keyword(s):  
Steady State ◽  
Streamline Flow ◽  
Longitudinal Diffusion ◽  
Basic Scheme ◽  
First Order ◽  
First Order Kinetics ◽  
Simplifying Assumptions ◽  
Mathematical Equations ◽  
Future Work ◽  
The Impact

Deterministic mathematical equations are derived to describe the pattern of marker excretion in the faeces of ruminants under steady-state conditions when diffusion and viscosity concepts are introduced into a simple two-compartment scheme of the gastrointestinal tract. The basic scheme comprises a pure-mixing pool obeying first-order kinetics and a second compartment exhibiting streamline flow. Introduction of a velocity gradient, longitudinal diffusion or both into the second compartment, even with various simplifying assumptions, yields analytically insoluble equations. The impact of these mechanisms is to be investigated numerically rather than analytically in future work.

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