Nonsmooth and level-resolved dynamics illustrated with the tight binding model

We point out that in the first order time-dependent perturbation theory, the transition probability may behave nonsmoothly in time and have kinks periodically. Moreover, the detailed temporal evolution can be sensitive to the exact locations of the eigenvalues in the continuum spectrum, in contrast to coarse-graining ideas. Underlying this nonsmooth and level-resolved dynamics is a simple equality about the sinc function \sinc x \equiv \sin x / x. These physical effects appear in many systems with approximately equally spaced spectra, and is also robust for larger-amplitude coupling beyond the domain of perturbation theory. We use a one-dimensional periodically driven tight-binding model to illustrate these effects, both within and outside the perturbative regime.Comment: Link with the Paley-Wiener theorem and another reference is added; any comment is welcome and will be greatly appreciated

DFT based study on structural stability and transport properties of Sr3AsN: A potential thermoelectric material

Antiperovskite materials are well known for their high thermoelectric performance and gained huge research interest. Here, we report the structural stability and transport properties of Sr$_3$AsN from a precise first-principles study. The calculated equilibrium lattice parameters are in a good agreement with the available data. We find that Sr$_3$AsN is a mechanically, energetically and dynamically stable at ambient condition. Our calculated electronic structure indicates that it is a direct bandgap semiconductor, with a value ~1.2 eV. Sr-4d and N-2p orbitals mainly formulate the direct bandgap. This antiperovskite possesses a high Seebeck coefficient. Although its lattice thermal conductivity is comparatively low, electronic thermal conductivity is very high. The calculated maximum TE figure of merit is 0.75 at 700 K, indicating that it is a potential material for thermoelectric applications.Comment: 22 pages, 11 figure

High Seebeck coefficient and ultra-low lattice thermal conductivity in Cs2InAgCl6

The elastic, electronic and thermoelectric properties of indium-based double-perovskite halide, Cs2InAgCl6 have been studied by first principles study. The Cs2InAgCl6 is found to be elastically stable, ductile, anisotropic and relatively low hard material. The calculated direct bandgap 3.67 eV by TB-mBJ functional fairly agrees with the experimentally measured value 3.3 eV but PBE functional underestimates the bandgap by 1.483 eV. The relaxation time and lattice thermal conductivity have been calculated by using relaxation time approximation (RTA) within the supercell approach. The lattice thermal conductivity (\k{appa}l) is quite low (0.2 Wm-1K-1). The quite low phonon group velocity in the large weighted phase space, and high anharmonicity (large phonon scattering) are responsible for small \k{appa}l. The room temperature Seebeck coefficient is 199 {\mu}VK-1. Such high Seebeck coefficient arises from the combination of the flat conduction band and large bandgap. We obtain power factors at 300K by using PBE and TB-mBJ potentials are ~29 and ~31 mWm-1K-2, respectively and the corresponding thermoelectric figure of merit of Cs2BiAgCl6 are 0.71 and 0.72. However, the maximum ZT value obtained at 700K is ~0.74 by TB-mBJ potential. The obtained results implies that Cs2InAgCl6 is a promising material for thermoelectric device applications.Comment: 19 pages. arXiv admin note: text overlap with arXiv:1801.0370

Physical biology of biomembranes and biomolecules (PHYBIOM)

To study mechanical properties of red blood cells, the combination of an AC dielectrophoretic apparatus and a single-beam optical tweezers were used. The experiments were performed with high frequency (e.g. 10 MHz) below the second turnover point between positive and negative dielectrophoresis. The electronic response of RBCs is dominated by the local interactions with the trapping beams. The elastic modulus was determined (μ = 1.80 ± 0.5 μN/m) by measuring the geometrical parameters of RBCs as a function of an applied voltage. However, the deformation of the red cell membrane was determined (Deformed gradient =0.08) from the maximum applied voltage when a spherical RBC escapes to the electrode from the trapping centre. These results were compared with similar experimental values obtained from other techniques. This is easy to use an alternative method to determine the mechanical properties of RBCs. Solute transport across cell membranes (e.g. RBC membrane) is the ubiquitous phenomenon, whose diffusion rate depends on the narrowest portion of membrane pores and the architecture of diffusing solutes. When a solute is confined in the critical area of membrane pores, which shows a quite different behavior compared to the homogenous bulk fluid whose transport is isotropic in all directions. The solute size and shape have been determined using the allometric scaling law, which explores the variation in the diffusion coefficient for solutes of different size and structure in physiological environments. Overall rates of diffusion through cell membranes have been determined based on membrane composition, local architecture, and the extend of binding. The functional group structures of protein folding (e.g. RBCs membrane protein) have been investigated using classical quantum biology based on infrared spectroscopy in polar groups capable of forming hydrogen bonds. The equivalence of infrared radiant energy and the bending energy of oscillating atoms along bonds is reliant on the reduced Planck constant, reduced mass and bond stiffness. The defined quantum biological equation is used to determine the deformation value changes from its equilibrium bond angle, which is estimated from the molecular geometry, in the hydrogen-bonded section of a polypeptide chain. This approach also quantifies substrates fit into the active sites of receptors by modifying the lock and key model. Proper protein folding determination is the minimization of free potential energy and adds order to the system. However, the hydrophobic force at protein side chains has been determined by the enthalpic effect of solutes, which may play a crucial role in protein misfolding. The “wrong” solutes are the hydrophobic dominated effect, which is the major driving force for protein misfolding. The interactions between hydrophobic solutes and protein side chains involve the rearrangement of side chains by disrupting protein backbone hydrogen bonds. The hydrophobic interaction is a thermodynamic process, which has been investigated by minimizing the potential energy that changes from enthalpy to thermal energy or vice versa as a temperature. Therefore, the enthalpic temperature due to macromolecular deformation defines the temperature limit for protein misfolding. The deformation temperature limit is the lowest possible temperature achievable with protein misfolding

Policies to Facilitate Conversion of Millions of Acres to the Production of Biofuel Feedstock

First-generation grain ethanol biofuel has affected the historical excess capacity problem in U.S. agriculture. Second-generation cellulosic ethanol biofuel has had difficulty achieving cost-competitiveness. Third-generation drop-in biofuels are under development. If lignocellulosic biomass from perennial grasses becomes the feedstock of choice for second- and third-generation biorefineries, an integrated system could evolve in which a biorefinery directly manages feedstock production, harvest, storage, and delivery. Modeling was conducted to determine the potential economic benefits from an integrated system. Relatively low-cost public policies that could be implemented to facilitate economic efficiency are proposed.biomass, bio-oil, cellulosic, drop-in fuels, ethanol, land-lease contract, lignocellulosic, pyrolysis, switchgrass, Resource /Energy Economics and Policy, Q16, Q18, Q15, Q42,

Revenue-enhancing Trade Liberalization in Developing Countries

Recovering revenue loss due to the reduction in import tariffs is a major concern of many developing economies. In an economy with free entry, which affects the product market competition, we show that, even if there is no other tax reform such as a profit tax reform, the market mechanism itself takes care of the loss of government revenue following a tariff reduction if entry is sufficiently costly. A compensatory profit tax to compensate the loss of government revenue following a tariff reduction is required for an intermediate level of entry cost. If the entry cost is very small, the loss of government revenue following a tariff reduction cannot be compensated even with a profit tax reform. Hence, the net effect of a tariff reduction on government revenue therefore depends on how much tariff and tax revenues are created by entry, which is affected by changes in both the tariff rate and the profit tax rate.Free Entry; Entry Cost; Trade Liberalization

Entanglement spectrum of the Heisenberg XXZ chain near the ferromagnetic point

We study the entanglement spectrum (ES) of a finite XXZ spin 1/2 chain in the limit \Delta -> -1^+ for both open and periodic boundary conditions. At \Delta=-1 (ferromagnetic point) the model is equivalent to the Heisenberg ferromagnet and its degenerate ground state manifold is the SU(2) multiplet with maximal total spin. Any state in this so-called "symmetric sector" is an equal weight superposition of all possible spin configurations. In the gapless phase at \Delta>-1 this property is progressively lost as one moves away from the \Delta=-1 point. We investigate how the ES obtained from the states in this manifold reflects this change, using exact diagonalization and Bethe ansatz calculations. We find that in the limit \Delta ->-1^+ most of the ES levels show divergent behavior. Moreover, while at \Delta=-1 the ES contains no information about the boundaries, for \Delta>-1 it depends dramatically on the choice of boundary conditions. For both open and periodic boundary conditions the ES exhibits an elegant multiplicity structure for which we conjecture a combinatorial formula. We also study the entanglement eigenfunctions, i.e. the eigenfunctions of the reduced density matrix. We find that the eigenfunctions corresponding to the non diverging levels mimic the behavior of the state wavefunction, whereas the others show intriguing polynomial structures. Finally we analyze the distribution of the ES levels as the system is detuned away from \Delta=-1.Comment: 21 pages, 8 figures. Minor corrections, references added. Published versio

Switchgrass to Ethanol: A Field to Fuel Approach

The U.S. Energy Independence and Security Act of 2007 mandates the production of 16 billion gallons of cellulosic biofuels by 2022. Desirable feedstock properties, biomass to biofuel conversion rate, and investment required in plant and equipment differs depending on which of several competing technologies is used. The objective is to determine the breakeven ethanol price for a cellulosic biorefinery. A comprehensive mathematical programming model that encompasses the chain from land acquisition to ethanol production was constructed and solved. For a capital requirement of $400 million for a 100 million gallons per year plant and a conversion rate of 100 gallons of ethanol per dry ton, the breakeven ethanol price is$1.91 per gallon: $0.20 for land rental and switchgrass production;$0.14 for feedstock harvest; $0.18 for feedstock storage and transportation;$0.75 for biorefinery operation and maintenance; and $0.64 for biorefinery investment. Biomass to ethanol conversion rate and the cost of biorefinery construction, operation, and maintenance are critical issues.biorefinery, breakeven price, cellulosic ethanol, mathematical programming, switchgrass, Agricultural and Food Policy, Crop Production/Industries, Production Economics, Q42, Q48,