scholarly journals Rapid compressions in a captive bubble apparatus are isothermal

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.

Kinetics of NO2 air space absorption in isolated rat lungs

1992 ◽  
Vol 73 (5) ◽  
pp. 1939-1945 ◽  
Author(s):  
E. M. Postlethwait ◽  
S. D. Langford ◽  
A. Bidani
Keyword(s):  
Steady State ◽  
Tidal Volume ◽  
Gas Phase ◽  
Initial Rate ◽  
Quasi Steady State ◽  
Closed Chamber ◽  
First Order ◽  
First Order Kinetics ◽  
Rat Lungs ◽  
Kinetics Of

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)

Low-temperature condensation of carbonaceous dust grains from PAHs

2019 ◽  
Vol 15 (S350) ◽  
pp. 465-467
Author(s):  
Lisseth Gavilan Marin ◽  
Salma Bejaoui ◽  
Gregory Gate ◽  
Michael Haggmark ◽  
Nathan Svadlenak ◽  
...  
Keyword(s):  
Low Temperature ◽  
Gas Phase ◽  
Solid Particles ◽  
Dust Grains ◽  
Supersonic Expansion ◽  
Laser Desorption Mass Spectrometry ◽  
Parent Molecule ◽  
Aromatic Molecules ◽  
Gas Phase Molecules ◽  
Two Phases

AbstractInterstellar carbon has been detected in both gas-phase molecules and solid particles. The goal of this study is to identify the link between these two phases of cosmic carbon. Here we report preliminary results on the low temperature formation of carbonaceous dust grains from gas-phase aromatic hydrocarbon precursors. This is done using the supersonic expansion of an argon jet seeded with aromatic molecules and exposed to an electrical discharge. We report experimental evidence of efficient carbon dust condensation from aromatic molecules including benzene and naphthalene. The molecular content of the solid grains is probed with laser desorption mass spectrometry. The mass spectra reveal a rich molecular composition including fragments of the parent molecule but also growth into larger molecular species.

Di-tert-butyl peroxide decomposition behind shock waves

1976 ◽  
Vol 54 (4) ◽  
pp. 581-585 ◽  
Author(s):  
David K. Lewis
Keyword(s):  
Thermal Decomposition ◽  
Gas Phase ◽  
Single Pulse ◽  
First Order ◽  
Tert Butyl ◽  
First Order Kinetics ◽  
Peroxide Decomposition ◽  
Butyl Peroxide ◽  
Temperature Work ◽  
Lower Temperature

The homogeneous, gas phase thermal decomposition of di-tert-butyl peroxide has been studied in a single pulse shock tube. Samples containing 0.05% to 0.5% reactant in argon were heated to 528–677 K at total pressures of about 1 atm. Acetone and ethane were the only significant products. The reaction obeyed first order kinetics. The Arrhenius parameters, log A (s−1) = 15.33 ± 0.50, Eact (kJ/mol) = 152.3 ± 5.8, are in agreement with the bulk of the earlier reported results of lower temperature work, and with a recently reported result obtained via the very low pressure pyrolysis technique. Indications from some of the earlier work that the A factor may decline at high temperatures are not supported by the present study.

Reactions with half-lives of several years

1964 ◽  
Vol 17 (4) ◽  
pp. 406 ◽  
Author(s):  
GA Bottomley ◽  
GL Nyberg
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Gas Phase ◽  
Virial Coefficient ◽  
Energy Equation ◽  
Second Virial Coefficient ◽  
First Order ◽  
First Order Kinetics ◽  
Reciprocal Temperature ◽  
Temperature Activation

The gas-phase thermal decomposition of dimethyldiazirine, (CH3)2CN2, at very slow rates has been investigated using precision gas-volumetric techniques previously applied to second virial coefficient studies. At 50-70� the first-order kinetics correspond to half-lives about 0.3-3.0 years. The present results, together with data obtained by other workers using conventional apparatus at 124-174�, fit a single log rate-reciprocal temperature activation energy equation.

Carbonyl fluoride formation by cw-CO2 laser-induced and sulfur hexafluoride-sensitized decomposition of hexafluoroacetone

1981 ◽  
Vol 46 (5) ◽  
pp. 1254-1257 ◽  
Author(s):  
Josef Pola ◽  
Pavel Engst ◽  
Milan Horák
Keyword(s):  
Gas Phase ◽  
Co2 Laser ◽  
Sulfur Hexafluoride ◽  
Phase Decomposition ◽  
First Order ◽  
First Order Kinetics ◽  
Cw Co2 Laser ◽  
Carbonyl Fluoride

The cw-CO2 laser-induced gas phase decomposition of hexafluoroacetone sensitized with sulfur hexafluoride (both 0.7-5.2 kPa) affords, besides perfluorinated hydrocarbons and minor amounts of trifluoroacetyl fluoride, carbonyl fluoride the formation of that obeys first-order kinetics and is favored with higher SF6 content.

Thermal decomposition of citraconic anhydride

1971 ◽  
Vol 24 (4) ◽  
pp. 771 ◽  
Author(s):  
NJ Daly ◽  
F Ziolkowski
Keyword(s):  
Carbon Dioxide ◽  
Thermal Decomposition ◽  
Gas Phase ◽  
Rate Constant ◽  
Arrhenius Equation ◽  
Volume Ratio ◽  
Reaction Vessel ◽  
First Order ◽  
First Order Kinetics ◽  
Citraconic Anhydride

Citraconic anhydride decomposes in the gas phase over the range 440- 490� to give carbon dioxide, carbon monoxide, and propyne which undergoes some polymerization to trimethylbenzenes. The decomposition obeys first-order kinetics, and the Arrhenius equation ������������������� k1 = 1015.64 exp(-64233�500/RT) (s-1) describes the variation of rate constant with temperature. The rate constant is unaffected by the addition of isobutene or by increase in the surface/volume ratio of the reaction vessel. The reaction appears to be unimolecular and if a diradical intermediate is involved it may not be fully formed in the transition state.

A further analysis of reciprocating flow in phloem tubes

1975 ◽  
Vol 53 (11) ◽  
pp. 1149-1152 ◽  
Author(s):  
D. M. Miller
Keyword(s):  
Lateral Diffusion ◽  
Sieve Tube ◽  
Mathematical Treatment ◽  
First Order ◽  
First Order Kinetics ◽  
Companion Cells ◽  
Static Phase ◽  
Two Phases ◽  
Quantitative Explanation ◽  
Reciprocating Flow

A more stringent mathematical treatment of reciprocating flow in phloem tubes has shown that the original model (Miller 1973) would be too inefficient to provide a quantitative explanation for the rate of solute dispersion within the tube. A modification is suggested in which the mobile phase consists of the sieve tube sap, and the companion cells constitute the static phase. Lateral diffusion of the solute between these two phases could occur through the cell wall barrier separating them via plasmodesmata and would follow first-order kinetics. It is shown that for optimum dispersion in such a model, the period of oscillation should be about 3.6 times the half life of the lateral diffusion process. Estimates of the various parameters involved indicate that such a mechanism, if driven by protoplasmic streaming, predicts a dispersion coefficient of the same order as those found experimentally.

scholarly journals A Comparison between the Rate of Reaction of Nitric Oxide in the Gas Phase and in Whole Cigarette Smoke

1985 ◽  
Vol 13 (2) ◽  
pp. 67-73 ◽  
Author(s):  
CDR Borland ◽  
AT Chamberlain ◽  
TW Higenbottam ◽  
RW Barber ◽  
BA Thrush
Keyword(s):  
Nitric Oxide ◽  
Gas Phase ◽  
Cigarette Smoke ◽  
Single Port ◽  
First Order ◽  
First Order Kinetics ◽  
Rate Of Reaction ◽  
Pseudo Second Order ◽  
Oxidation Of No ◽  
Whole Smoke

AbstractThere remains uncertainty about the rate of oxidation of nitric oxide (NO) in cigarette smoke. Using a single-port smoking machine and a chemiluminescence NO analyser we have investigated the rate of NO disappearance during cigarette smoke ageing over 10 minutes for gas phase and whole smoke. The disappearance of NO in whole smoke conformed to the (pseudo) second order kinetics observed for oxidation of NO in air. In the gas phase however the rate of disappearance was more rapid and appeared to follow first order kinetics. The possible mechanisms for this difference in behaviour are discussed.

Adsorption Thermodynamics and Kinetics of Lipoic Acid on Three Types of Resin

2010 ◽  
Vol 96 ◽  
pp. 7-14 ◽  
Author(s):  
Rui Xia Wei ◽  
Jin Long Chen ◽  
Cai Ling Yang
Keyword(s):  
Lipoic Acid ◽  
Capillary Condensation ◽  
Adsorption Thermodynamics ◽  
Volume Filling ◽  
First Order ◽  
Thermodynamics And Kinetics ◽  
First Order Kinetics ◽  
Two Phases ◽  
Adsorption Rates ◽  
Kinetics Of

Study on adsorption thermodynamics and kinetics of Lipoic acid by NG-16, NDA-100 and ND-90 resin was carried out through static experiments. The results showed that the adsorption of Lipoic acid on NG-16 resin is Langmuir monolayer, and the adsorption rate appears to be the first order kinetics. The adsorption date of Lipoic acid on NDA-100 and ND-90 resin also were described well by the Langmuir isotherm, which was caused by the capillary condensation and the volume filling of micropores besides monolayer adsorption. When the concentration of Lipoic acid is higher than 400mg/L, the capillary condensation and the volume filling of micropores act the main part. The adsorption of Lipoic acid on NDA-100 and ND-90 resin pass through two phases: macropores, mespores area and micropores area. And the adsorptions in micropores area are described well by the Dubinin-Radushkevich isotherm. The adsorption rates of the two phases are the first order kinetics.

Photo-catalytic degradation of gaseous pollutants in paper mills of southern China

TAPPI Journal ◽  
2018 ◽  
Vol 17 (03) ◽  
pp. 167-178 ◽  
Author(s):  
Xin Tong ◽  
Jiao Li ◽  
Jun Ma ◽  
Xiaoquan Chen ◽  
Wenhao Shen
Keyword(s):  
Degradation Rate ◽  
Southern China ◽  
Catalytic Degradation ◽  
Pulp And Paper ◽  
Gaseous Pollutants ◽  
Pulp And Paper Mills ◽  
Paper Mills ◽  
Initial Concentration ◽  
First Order ◽  
First Order Kinetics

Studies were undertaken to evaluate gaseous pollutants in workplace air within pulp and paper mills and to consider the effectiveness of photo-catalytic treatment of this air. Ambient air at 30 sampling sites in five pulp and paper mills of southern China were sampled and analyzed. The results revealed that formaldehyde and various benzene-based molecules were the main gaseous pollutants at these five mills. A photo-catalytic reactor system with titanium dioxide (TiO2) was developed and evaluated for degradation of formaldehyde, benzene and their mixtures. The experimental results demonstrated that both formaldehyde and benzene in their pure forms could be completely photo-catalytic degraded, though the degradation of benzene was much more difficult than that for formaldehyde. Study of the photo-catalytic degradation kinetics revealed that the degradation rate of formaldehyde increased with initial concentration fitting a first-order kinetics reaction. In contrast, the degradation rate of benzene had no relationship with initial concentration and degradation did not conform to first-order kinetics. The photo-catalytic degradation of formaldehyde-benzene mixtures indicated that formaldehyde behaved differently than when treated in its pure form. The degradation time was two times longer and the kinetics did not reflect a first-order reaction. The degradation of benzene was similar in both pure form and when mixed with formaldehyde.

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