The rheology of gases. A molecular-dynamics study

Heyes, D. M.; Szczepanski, Richard

doi:10.1039/f29878300319

Cited by 19 publications

(3 citation statements)

References 10 publications

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“…58,59 The shear elastic modulus of the LJ FCC solid at T = 1 was computed in a separate bulk solid MD calculation. 60,61 At 100, 1000, and 5000 MPa pressure, the computed shear modulus values were, 1798, 4549, and 14429 MPa, respectively. Figure 11 presents the ratio of the shear stress to infinite frequency shear modulus as a function of wall speed at the three applied pressures.…”

Section: Resultsmentioning

confidence: 98%

Pressure dependence of confined liquid behavior subjected to boundary-driven shear

Heyes

Smith

Dini

et al. 2012

The Journal of Chemical Physics

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Non-equilibrium molecular dynamics simulations of boundary-driven sheared Lennard-Jones liquids at variable pressure up to 5 GPa (for argon) reveal a rich out-of-equilibrium phase behavior with a strong degree of shear localization. At the lowest apparent shear rate considered (wall speed ~1 m s(-1)) the confined region is an homogeneously sheared solid (S) with no slip at the walls. This transforms at higher shear rates to a non-flowing plug with slip at the walls, referred to as the plug slip (PS) state. At higher shear rate a central localized (CL) state formed in which the shear gradient was localized in the center of the film, with the rest of the confined sample in a crystalline state commensurate with the wall lattice. The central zone liquidlike region increased in width with shear rate. A continuous rounded temperature profile across the whole system reflects strong dynamical coupling between the wall and confined region. The temperature rise in the confined film is consistent with the Brinkman number. The transition from the PS to CL states typically occurred at a wall speed near where the shear stress approached a critical value of ~3% of the shear modulus, and also near the peak in the traction coefficient, μ. The peak traction coefficient values computed, ~0.12-0.14 at 1000 MPa agree with those found for traction fluids and occur when the confined liquid is in the PS and CL states. At low wall speeds slip can occur at one wall and stick at the other. Poorly wetting liquids manifest long-lived asymmetries in the confined liquid properties across the system, and a shift in solid-liquid phase co-existence to higher shear rates. A non-equilibrium phase diagram based on these results is proposed. The good agreement of the tribological response of the Lennard-Jones fluid with that of more complicated molecular systems suggests that a corresponding states scaling of the tribological behavior could apply.

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Section: Resultsmentioning

confidence: 98%

Pressure dependence of confined liquid behavior subjected to boundary-driven shear

Heyes

Smith

Dini

et al. 2012

The Journal of Chemical Physics

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“…Precursors for the biosynthesis of the nicotinamide moiety of NAD may also be provided by this pathway. Recently, kynurenine metabolites have been implicated in several neuropathological conditions (see [5]for a review). This has led to the cloning and characterization of the human 3‐HOA [6].…”

Section: Introductionmentioning

confidence: 99%

The yeast gene YJR025c encodes a 3‐hydroxyanthranilic acid dioxygenase and is involved in nicotinic acid biosynthesis

et al. 1998

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We have deleted the yeast gene YJR025c and shown that this leads to an auxotrophy for nicotinic acid. The deduced protein sequence of the gene product is homologous to the human 3-hydroxyanthranilic acid dioxygenase (EC 1.13.11.6) which is part of the kynurenine pathway for the degradation of tryptophan and the biosynthesis of nicotinic acid. In cell-free extracts the 3-hydroxyanthranilic acid dioxygenase activity is proportional to the copy number of the YJR025c gene. As YJR025c encodes the yeast 3-hydroxyanthranilic acid dioxygenase, we have named this gene BNA1 for biosynthesis of nicotinic acid.z 1998 Federation of European Biochemical Societies.

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“…Accumulation of kynurenine metabolites may, in fact, constitute a potentially hazardous event. Quinolinic acid is a potent excitotoxin [1]and its overproduction by activated brain‐invading macrophages and/or microglial cells has been linked to neuronal damage occurring in neuroinflammatory disorders [2–4]. Relatively high concentrations of l ‐3‐hydroxykynurenine may also be neurotoxic and a recent report suggests that this metabolite mediates neuronal cell death through H 2 O 2 production [5].…”

Section: Introductionmentioning

confidence: 99%