Tracing shock type with chemical diagnostics

Aims. The physical structure of a shock wave may take a form unique to its shock type, implying that the chemistry of each shock type is unique as well. We aim to investigate the different chemistries of J-type and C-type shocks in order to identify unique molecular tracers of both shock types. We apply these diagnostics to the protostellar outflow L1157 to establish whether the B2 clump could host shocks exhibiting type-specific behaviour. Of particular interest is the L1157-B2 clump, which has been shown to exhibit bright emission in S-bearing species and HNCO. Methods. We simulate, using a parameterised approach, a planar, steady-state J-type shock wave using UCLCHEM. We compute a grid of models using both C-type and J-type shock models to determine the chemical abundance of shock-tracing species as a function of distance through the shock and apply it to the L1157 outflow. We focus on known shock-tracing molecules such as H2O, HCN, and CH3OH. Results. We find that a range of molecules including H2O and HCN have unique behaviour specific to a J-type shock, but that such differences in behaviour are only evident at low vs and low nH. We find that CH3OH is enhanced by shocks and is a reliable probe of the pre-shock gas density. However, we find no difference between its gas-phase abundance in C-type and J-type shocks. Finally, from our application to L1157, we find that the fractional abundances within the B2 region are consistent with both C-type and J-type shock emission.

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Simulation of a Steady-State Electron Shock Wave in a Submicron Semiconductor Device Using High-Order Upwind Methods

Computational Electronics ◽

10.1007/978-1-4757-2124-9_4 ◽

1991 ◽

pp. 27-32 ◽

Cited By ~ 3

Author(s):

Emad Fatemi ◽

Carl L. Gardner ◽

Joseph W. Jerome ◽

Stanley Osher ◽

Donald J. Rose

Keyword(s):

Shock Wave ◽

Steady State ◽

Semiconductor Device ◽

High Order ◽

State Electron ◽

Upwind Methods

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Mitochondrial function in the presence of myoglobin

Journal of Applied Physiology ◽

10.1152/jappl.1982.53.5.1116 ◽

1982 ◽

Vol 53 (5) ◽

pp. 1116-1124 ◽

Cited By ~ 40

Author(s):

R. P. Cole ◽

P. C. Sukanek ◽

J. B. Wittenberg ◽

B. A. Wittenberg

Keyword(s):

Oxygen Consumption ◽

Steady State ◽

Liquid Phase ◽

Gas Phase ◽

Oxygen Pressure ◽

Oxygen Electrode ◽

Oxygen Binding ◽

Atp Production ◽

Skeletal Muscle Mitochondria ◽

The Difference

The effect of myoglobin on oxygen consumption and ATP production by isolated rat skeletal muscle mitochondria was studied under steady-state conditions of oxygen supply. A method is presented for the determination of steady-state oxygen consumption in the presence of oxygen-binding proteins. Oxygen consumed in suspensions of mitochondria was replenished continuously by transfer from a flowing gas phase. Liquid-phase oxygen pressure was measured with an oxygen electrode; the gas-phase oxygen concentration was held constant at a series of fixed values. Oxygen consumption was determined from the characteristic response time of the system and the difference in the steady-state gas- and liquid-phase oxygen concentrations. ATP production was determined from the generation of glucose 6-phosphate in the presence of hexokinase. During steady-state mitochondrial oxygen consumption, the oxygen pressure in the liquid phase is enhanced when myoglobin is present. Functional myoglobin present in the solution had no effect on the relation of mitochondrial respiration and ATP production to liquid-phase oxygen pressure. Myoglobin functions in this system to enhance the flux of oxygen into the myoglobin-containing phase. Myoglobin may function in a similar fashion in muscle by increasing oxygen flux into myocytes.

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A semi-analytical method for calculating rates of new sulfate aerosol formation from the gas phase

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-7-2169-2007 ◽

2007 ◽

Vol 7 (1) ◽

pp. 2169-2196 ◽

Cited By ~ 1

Author(s):

J. Kazil ◽

E. R. Lovejoy

Keyword(s):

Steady State ◽

Gas Phase ◽

Nucleation Rate ◽

Atmospheric Modeling ◽

Sulfate Aerosol ◽

Nucleation Theory ◽

Rate Coefficients ◽

Classical Nucleation Theory ◽

Aerosol Formation ◽

Aerosol Model

Abstract. The formation of new sulfate aerosol from the gas phase is commonly represented in atmospheric modeling with parameterizations of the steady state nucleation rate. Such parameterizations are based on classical nucleation theory or on aerosol nucleation rate tables, calculated with a numerical aerosol model. These parameterizations reproduce aerosol nucleation rates calculated with a numerical aerosol model only imprecisely. Additional errors can arise when the nucleation rate is used as a surrogate for the production rate of particles of a given size. We discuss these errors and present a method which allows a more precise calculation of steady state sulfate aerosol formation rates. The method is based on the semi-analytical solution of an aerosol system in steady state and on parameterized rate coefficients for H2SO4 uptake and loss by sulfate aerosol particles, calculated from laboratory and theoretical thermodynamic data.

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Formation of carbon nanoparticles from the gas phase in shock wave pyrolysis processes

Progress in Energy and Combustion Science ◽

10.1016/j.pecs.2011.09.002 ◽

2012 ◽

Vol 38 (1) ◽

pp. 1-40 ◽

Cited By ~ 35

Author(s):

Alexander V. Eremin

Keyword(s):

Shock Wave ◽

Gas Phase ◽

Carbon Nanoparticles ◽

Pyrolysis Processes

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Graphenylene and Inorganic Graphenylene Nanopores for Gas-Phase 4He/3He Separation: Kinetic and Steady-State Considerations

Physical Chemistry Chemical Physics ◽

10.1039/d0cp05755j ◽

2021 ◽

Author(s):

Maryam Sadat Motallebipour ◽

Javad Karimi-Sabet

Keyword(s):

Steady State ◽

Gas Phase ◽

Quantum Tunneling ◽

Zero Point ◽

Selective Membrane ◽

Quantum Phenomena ◽

Mass Dependent

Selective membrane-based separation of light isotopes is considered to be possible based on the quantum phenomena. In this regard, the role of the two mass-dependent effects, quantum tunneling and zero-point...

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Kinetics of NO2 air space absorption in isolated rat lungs

Journal of Applied Physiology ◽

10.1152/jappl.1992.73.5.1939 ◽

1992 ◽

Vol 73 (5) ◽

pp. 1939-1945 ◽

Cited By ~ 6

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)

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Star formation and gas flow history of a dwarf irregular galaxy traced by gas-phase and stellar metallicities

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3104 ◽

2019 ◽

Vol 491 (2) ◽

pp. 1759-1770

Author(s):

Nao Fukagawa

Keyword(s):

Star Formation ◽

Gas Phase ◽

Gas Flow ◽

Building Blocks ◽

Gas Flows ◽

Chemical Abundance ◽

Irregular Galaxy ◽

Oxygen Abundance ◽

History Of ◽

Ngc 6822

ABSTRACT Studying the evolution of dwarf galaxies can provide insights into the characteristics of systems that can act as building blocks of massive galaxies. This paper discusses the history of star formation and gas flows (inflow and outflow) of a dwarf irregular galaxy in the Local Group, NGC 6822, from the viewpoint of gas-phase and stellar chemical abundance. Gas-phase oxygen abundance, stellar metallicity distribution, and gas fraction data are compared to chemical evolution models in which continuous star formation and gas flows are assumed. If the galaxy is assumed to be a closed or an accretion-dominated system where steeper stellar initial mass functions are allowed, the observed gas-phase oxygen abundance and gas fraction can be explained simultaneously; however, metallicity distributions predicted by the models seem to be inconsistent with the observed distribution, which suggests that the star formation, gas flows, and/or chemical enrichment are more complex than assumed by the models. When NGC 6822 is assumed to be a system dominated by outflow, the observed values of gas-phase oxygen abundance and gas fraction can be explained, and the metallicity distributions predicted by some of the models are also roughly consistent with the observed distribution in the metallicity range of −2.0 ≲ [Fe/H] ≲ −0.5. It should be noted that this result does not necessarily mean that the accretion of gas is completely ruled out. More observables, such as chemical abundance ratios, and detailed modelling may provide deeper insight into the evolution of the system.

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Modelling post-discharge nitriding and nitrocarburising

Journal de Physique IV (Proceedings) ◽

10.1051/jp4:2004120028 ◽

2004 ◽

Vol 120 ◽

pp. 239-247

Author(s):

T. Belmonte ◽

C. Jaoul ◽

H. Michel

Keyword(s):

Steady State ◽

Ternary System ◽

Gas Phase ◽

Gas Flow ◽

State Of The Art ◽

Active Species ◽

Surface Phenomena ◽

Post Discharge ◽

Two Phase ◽

Adsorption Surface

In this paper, the state of the art in the modelling of nitriding and nitrocarburising using late post-discharge processes is described. In a first part, interstitial diffusion in ternary system is treated. The problem of the diffusion in two-phase domains is evoked. The chemical pathways in N2-H2 and N2-CH4 post-discharges creating active species are next presented to try to identify the precursors responsible for the transport of nitrogen and carbon to the surface of the solid. Finally, attention is paid to the coupling between the gas phase and the solid. Two different approaches are proposed, either by considering a steady state or a transient gas flow. The latter requires to introduce a sequence of surface phenomena (adsorption, surface diffusion, recombination, dissolution…) that provides a rigorous way to couple processes in the gas phase and in the solid.

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