Kinetics of NO2 air space absorption in isolated rat lungs

We previously showed, during quasi-steady-state exposures, that the rate of inhaled NO2 uptake displays reaction-mediated characteristics (J. Appl. Physiol. 68: 594–603, 1990). In vitro kinetic studies of pulmonary epithelial lining fluid (ELF) demonstrated that NO2 interfacial transfer into ELF exhibits first-order kinetics with respect to NO2, attains [NO2]-dependent rate saturation, and is aqueous substrate dependent (J. Appl. Physiol. 71: 1502–1510, 1991). We have extended these observations by evaluating the kinetics of NO2 gas phase disappearance in isolated ventilating rat lungs. Transient exposures (2–3/lung at 25 degrees C) employed rebreathing (NO2-air) from a non-compliant continuously stirred closed chamber. We observed that 1) NO2 uptake rate is independent of exposure period, 2) NO2 gas phase disappearance exhibited first-order kinetics [initial rate (r*) saturation occurred when [NO2] > 11 ppm], 3) the mean effective rate constant (k*) for NO2 gas phase disappearance ([NO2] < or = 11 ppm, tidal volume = 2.3 ml, functional residual capacity = 4 ml, ventilation frequency = 50/min) was 83 +/- 5 ml/min, 4) with [NO2] < or = 11 ppm, k* and r* were proportional to tidal volume, and 5) NO2 fractional uptakes were constant across [NO2] (< or = 11 ppm) and tidal volumes but exceeded quasi-steady-state observations. Preliminary data indicate that this divergence may be related to the inspired PCO2. These results suggest that NO2 reactive uptake within rebreathing isolated lungs follows first-order kinetics and displays initial rate saturation, similar to isolated ELF.(ABSTRACT TRUNCATED AT 250 WORDS)

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Kinetics of Biocatalytical Synergistic Reactions

Nonlinear Analysis Modelling and Control ◽

10.15388/na.2005.10.3.15121 ◽

2005 ◽

Vol 10 (3) ◽

pp. 223-233 ◽

Cited By ~ 4

Author(s):

J. Kulys

Keyword(s):

Steady State ◽

Analytical Solution ◽

Differential Equations ◽

Ordinary Differential Equations ◽

Stationary State ◽

Initial Rate ◽

Kinetic Constants ◽

Quasi Steady State ◽

The Novel ◽

Kinetics Of

Kinetics of biocatalytical synergistic reactions has been analyzed at non-stationary state (NSS) and at quasi steady state (QSS) conditions. The application to the model kinetic constants taken from the first type of the experiments shows that QSS can be established for the enzyme and the mediator at time less than 1 s. Therefore, the analytical solution of the initial rate (IR) may be produced at relevant to an experiment time, and the dependence of the IR on substrates concentration may be analyzed rather easy. The use of kinetic constants from the second type of reactions shows that QSS is formed for the enzyme but not for the mediator. For this reason the modeling of the synergistic process was performed by solving the ordinary differential equations (ODE). For this purpose the novel program KinFitSim (c) was used.

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Photoinitiated Polymerization of 2-Hydroxyethyl Methacrylate by Riboflavin/Triethanolamine in Aqueous Solution: A Kinetic Study

ISRN Pharmaceutics ◽

10.1155/2013/958712 ◽

2013 ◽

Vol 2013 ◽

pp. 1-7 ◽

Cited By ~ 4

Author(s):

Iqbal Ahmad ◽

Kefi Iqbal ◽

Muhammad Ali Sheraz ◽

Sofia Ahmed ◽

Tania Mirza ◽

...

Keyword(s):

Initial Rate ◽

Hydroxyl Group ◽

Hydroxyethyl Methacrylate ◽

First Order ◽

First Order Kinetics ◽

Rate Of Polymerization ◽

Rate Of Reaction ◽

Ph Range ◽

Kinetics Of ◽

Increased Activity

The polymerization of 1–3 M 2-hydroxyethyl methacrylate (HEMA) initiated by riboflavin/triethanolamine system has been studied in the pH range 6.0–9.0. An approximate measure of the kinetics of the reaction during the initial stages (~5% HEMA conversion) has been made to avoid the effect of any variations in the volume of the medium. The concentration of HEMA in polymerized solutions has been determined by a UV spectrophotometric method at 208 nm with a precision of ±3%. The initial rate of polymerization of HEMA follows apparent first-order kinetics and the rates increase with pH. This may be due to the presence of a labile proton on the hydroxyl group of HEMA. The second-order rate constants for the interaction of triethanolamine and HEMA lie in the range of 2.36 to M−1 s−1 at pH 6.0–9.0 suggesting an increased activity with pH. An increase in the viscosity of HEMA solutions from 1 M to 3 M leads to a decrease in the rate of polymerization probably as a result of the decrease in the reactivity of the flavin triplet state. The effect of pH and viscosity of the medium on the rate of reaction has been evaluated.

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Kinetic of oxidation of methyl orange by vanadium(V) under conditions VO2+ and decavanadates coexist: Catalysis by Triton X-100 micellar medium

10.31221/osf.io/m9g7p ◽

2019 ◽

Author(s):

Chem Int

Keyword(s):

Methyl Orange ◽

Solution Ph ◽

Vanadium Concentration ◽

Limiting Behavior ◽

First Order ◽

First Order Kinetics ◽

Ph Range ◽

Kinetic Pattern ◽

Triton X ◽

Kinetics Of

The kinetics of oxidation of methyl orange by vanadium(V) {V(V)} has been investigated in the pH range 2.3-3.79. In this pH range V(V) exists both in the form of decavanadates and VO2+. The kinetic results are distinctly different from the results obtained for the same reaction in highly acidic solution (pH < 1) where V(V) exists only in the form of VO2+. The reaction obeys first order kinetics with respect to methyl orange but the rate has very little dependence on total vanadium concentration. The reaction is accelerated by H+ ion but the dependence of rate on [H+] is less than that corresponding to first order dependence. The equilibrium between decavanadates and VO2+ explains the different kinetic pattern observed in this pH range. The reaction is markedly accelerated by Triton X-100 micelles. The rate-[surfactant] profile shows a limiting behavior indicative of a unimolecular pathway in the micellar pseudophase.

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Comparative Study of Chemical Stability of Two H1Antihistaminic Drugs, Terfenadine and ItsIn VivoMetabolite Fexofenadine, Using LC-UV Methods

Journal of Analytical Methods in Chemistry ◽

10.1155/2019/5790404 ◽

2019 ◽

Vol 2019 ◽

pp. 1-10

Author(s):

Anna Gumieniczek ◽

Anna Berecka-Rycerz ◽

Rafał Pietraś ◽

Izabela Kozak ◽

Karolina Lejwoda ◽

...

Keyword(s):

Comparative Study ◽

Chemical Stability ◽

First Order ◽

First Order Kinetics ◽

Kinetics Of Degradation ◽

Effects Of Temperature ◽

High Doses ◽

Antihistaminic Drugs ◽

Kinetics Of

A comparative study of chemical stability of terfenadine (TER) and itsin vivometabolite fexofenadine (FEX) was performed. Both TER and FEX were subjected to high temperature at different pH and UV/VIS light at different pH and then quantitatively analyzed using new validated LC-UV methods. These methods were used to monitor the degradation processes and to determine the kinetics of degradation for both the compounds. As far as the effects of temperature and pH were concerned, FEX occurred more sensitive to degradation than TER. As far as the effects of UV/VIS light and pH were concerned, the both drugs were similarly sensitive to high doses of light. Using all stress conditions, the processes of degradation of TER and FEX followed the first-order kinetics. The results obtained for these two antihistaminic drugs could be helpful in developing their new derivatives with higher activity and stability at the same time.

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Kinetics of Biofilm Detachment

Water Science & Technology ◽

10.2166/wst.1992.0645 ◽

1992 ◽

Vol 26 (9-11) ◽

pp. 1995-1998 ◽

Cited By ~ 22

Author(s):

B. M. Peyton ◽

W. G. Characklis

Keyword(s):

Steady State ◽

Utilization Rate ◽

Carbon Utilization ◽

Biofilm Thickness ◽

First Order ◽

Detachment Rate ◽

Biofilm Detachment ◽

Biofilm Modeling ◽

Kinetics Of ◽

Sensitive Variable

In predictive biofilm modeling, the detachment rate coefficient may be the most sensitive variable affecting both the predicted rate and the extent of biofilm accumulation. At steady state the detachment rate must be equal to the net growth rate in the biofilm. In systems where organic carbon is growth-limiting, the substrate carbon utilization rate determines the net biomass production rate and, therefore, the steady state biomass detachment rate. Detachment rates, first order with biofilm thickness, fit the experimental data well, but are not predictive since the coefficients must be determined experimentally.

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Evidence for nonvectorial, retrograde transferrin trafficking in the early endosomes of HEp2 cells.

The Journal of Cell Biology ◽

10.1083/jcb.128.4.549 ◽

1995 ◽

Vol 128 (4) ◽

pp. 549-561 ◽

Cited By ~ 82

Author(s):

R N Ghosh ◽

F R Maxfield

Keyword(s):

Steady State ◽

Digital Image Analysis ◽

Carcinoma Cells ◽

Exit Rate ◽

Human Carcinoma ◽

First Order ◽

First Order Kinetics ◽

Early Endosomes ◽

Retrograde Traffic ◽

Endosomal System

We have previously characterized the trafficking of transferrin (Tf) through HEp2 human carcinoma cells (Ghosh, R. N., D. L. Gelman, and F. R. Maxfield, 1994. J. Cell Sci. 107:2177-2189). Early endosomes in these cells are comprised of both sorting endosomes and recycling compartments, which are distinct separate compartments. Endocytosed Tf initially appears in punctate sorting endosomes that also contain recently endocytosed LDL. After short loading pulses, Tf rapidly sorts from LDL with first-order kinetics (t1/2 approximately 2.5 min), and it enters the recycling compartment before leaving the cell (t1/2 approximately 7 min). Here, we report a second, slower rate for Tf to leave sorting endosomes after HEp2 cells were labeled to steady state with fluorescein Tf instead of the brief pulse used previously. We determined this rate using digital image analysis to measure the Tf content of sorting endosomes that also contained LDL. With an 11-min chase, the Tf in sorting endosomes was 24% of steady-state value. This was in excess of the amount expected (5% of steady state) from the rate of Tf exit after short filling pulses. The excess could not be accounted for by reinternalization of recycled cell surface Tf, implying that either some Tf was retained in sorting endosomes, or that Tf was delivered back to the sorting endosomes from the recycling compartment. The former is unlikely since nearly all sorting endosomes contain detectable Tf after an 11-min chase, even though more than one third of the sorting endosomes were formed during the chase time. Furthermore, while observing living cells by confocal microscopy, we saw vesicle movements that appeared to be fluorescent Tf returning from recycling compartments to sorting endosomes. The slow rate of exit after steady-state labeling was similar to the Tf exit rate from the cell, suggesting an equilibration of Tf throughout the early endosomal system by this retrograde pathway. This retrograde traffic may be important for delivering molecules from the recycling compartment, which is a long-lived organelle, to sorting endosomes, which are transient.

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The mechanism of the oxidation of thiocyanate ion by peroxomonosulphate in aqueous solution. II. Kinetics of the reaction

Australian Journal of Chemistry ◽

10.1071/ch9661365 ◽

1966 ◽

Vol 19 (8) ◽

pp. 1365 ◽

Cited By ~ 4

Author(s):

RH Smith ◽

IR Wilson

Keyword(s):

Aqueous Solution ◽

Initial Rate ◽

Stopped Flow ◽

Thiocyanate Ion ◽

First Order ◽

Conductance Method ◽

Rate Of Reaction ◽

Kinetics Of

Initial rates of reaction for the above oxidation have been measured by a stopped-flow conductance method. Between pH 2 and 3.6, the initial rate of reaction, R, is given by the expression R{[HSO5-]+[SCN-]} = {kb+kc[H+]}[HSO5-]0[SCN-]20+ka[H+]-1[HSO5]20[SCN-]0 As pH increases, there is a transition to a pH-independent rate, first order in each thiocyanate and peroxomonosulphate concentrations.

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Rapid compressions in a captive bubble apparatus are isothermal

Journal of Applied Physiology ◽

10.1152/japplphysiol.00591.2003 ◽

2003 ◽

Vol 95 (5) ◽

pp. 1896-1900

Author(s):

Wenfei Yan ◽

Stephen B. Hall

Keyword(s):

Hydrostatic Pressure ◽

Gas Phase ◽

Pulmonary Surfactant ◽

First Order ◽

First Order Kinetics ◽

Gas Phase Molecules ◽

Actual Change ◽

Phase Temperature ◽

Two Phases ◽

Interfacial Films

Captive bubbles are commonly used to determine how interfacial films of pulmonary surfactant respond to changes in surface area, achieved by varying hydrostatic pressure. Although assumed to be isothermal, the gas phase temperature (Tg) would increase by >100°C during compression from 1 to 3 atm if the process were adiabatic. To determine the actual change in temperature, we monitored pressure (P) and volume (V) during compressions lasting <1 s for bubbles with and without interfacial films and used P · V to evaluate Tg. P · V fell during and after the rapid compressions, consistent with reductions in n, the moles of gas phase molecules, because of increasing solubility in the subphase at higher P. As expected for a process with first-order kinetics, during 1 h after the rapid compression P · V decreased along a simple exponential curve. The temporal variation of n moles of gas was determined from P · V >10 min after the compression when the two phases should be isothermal. Back extrapolation of n then allowed calculation of Tg from P · V immediately after the compression. Our results indicate that for bubbles with or without interfacial films compressed to >3 atm within 1 s, the change in Tg is <2°C.

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