A mathematically exact algorithmic approach is presented for carrying out the synthesis of the networks of plausible elementary or metabolic reactions constituting stoichiometrically exact and potentially feasible cat...
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A mathematically exact algorithmic approach is presented for carrying out the synthesis of the networks of plausible elementary or metabolic reactions constituting stoichiometrically exact and potentially feasible catalytic or metabolic pathways;this synthesis is profoundly complex combinatorially. The approach is based on the unique graph-representation in terms of P-graphs (process graphs), a set of axioms, and a group of combinatorial algorithms. The inclusion or exclusion of a step of each elementary or metabolic reaction in the pathway of interest hinges on the general combinatorial properties of feasible reaction networks. The methodology, on which the approach is based, is outlined at the outset. The methodology is then illustrated by implementing it to three examples comprising two catalytic reactions, i.e., catalytic combustion of hydrogen and reduction of nitrogen oxide, and one metabolic reaction, involved in the production of ethanol by yeast. The efficacy of the approach is discussed in light of the results obtained from these examples.
Through investigation of transient phase characteristics, a methodology is developed to optimize the phase resetting properties of robust nonlinear biological oscillators;in particular, those of the circadian rhythm. ...
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This Letter reports the laser energy dependence of the Stokes and anti-Stokes Raman spectra of carbon nanotubes dispersed in aqueous solution and within solid bundles, in the energy range 1.52–2.71 eV. The electronic...
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This Letter reports the laser energy dependence of the Stokes and anti-Stokes Raman spectra of carbon nanotubes dispersed in aqueous solution and within solid bundles, in the energy range 1.52–2.71 eV. The electronic transition energies (Eii) and the radial breathing mode frequencies (ωRBM) are obtained for 46 different (18 metallic and 28 semiconducting) nanotubes, and the (n,m) assignment is discussed based on the observation of geometrical patterns for Eii versus ωRBM graphs. Only the low energy component of the E11M value is observed from each metallic nanotube. For a given nanotube, the resonant window is broadened and down-shifted for single wall carbon nanotube (SWNT) bundles compared to SWNTs in solution, while by increasing the temperature, the E22S energies are redshifted for S1 [(2n+m) mod 3=1] nanotubes and blueshifted for S2 [(2n+m) mod 3=2] nanotubes.
When a direct current (DC) electric field is applied across an ion-selective nanoporous membrane or a nanochannel with an overlapping Debye layer, a surprising microvortex instability occurs on the side of the membran...
When a direct current (DC) electric field is applied across an ion-selective nanoporous membrane or a nanochannel with an overlapping Debye layer, a surprising microvortex instability occurs on the side of the membrane/channel through which counterions enter. Despite its micro and nano length scales, this instability exhibits all the hallmarks of other classical hydrodynamic instabilities—a subharmonic cascade, a wide-band fluctuation spectrum, and a coherent structure dominated by spatiotemporal dynamics. Moreover, the resulting convection enhances the ion flux into the ion-selective medium and gives rise to an overlimiting-current bifurcation in the current-voltage relationship. This hydrodynamically driven nonequilibrium ion flux does not seem to have any equivalent in cell membrane ion channels. Yet, by introducing asymmetric entrances to provide different polarized regions and/or viscous arrest of the vortex instability, one can fabricate a hydrodynamic nanofluidic diode. With other modifications, hysteretic, excitable, and oscillatory ion flux dynamics could also be elicited—all with strong hydrodynamic features.
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