Periodic Green's function for skewed 3‐D lattices using the Ewald transformation

Abstract

3‐Hydroxypropionic acid (3‐HP) is a commercially valuable chemical with the potential to be a key building block for deriving many industrially important chemicals. However, its biological production has not been well documented. Our previous study demonstrated the feasibility of producing 3‐HP from glycerol using the recombinant Escherichia coli SH254 expressing glycerol dehydratase (DhaB) and aldehyde dehydrogenase (AldH), and reported that an “imbalance between the two enzymes” and the “instability of the first enzyme DhaB” were the major factors limiting 3‐HP production. In this study, the efficiency of the recombinant strain(s) was improved by expressing DhaB and AldH in two compatible isopropyl‐thio‐β‐galactoside (IPTG) inducible plasmids along with glycerol dehydratase reactivase (GDR). The expression levels of the two proteins were measured. It was found that the changes in protein expression were associated with their enzymatic activity and balance. While cloning an alternate aldehyde dehydrogenase (ALDH), α‐ketoglutaric semialdehyde dehydrogenase (KGSADH), instead of AldH, the recombinant E. coli SH‐BGK1 showed the highest level of 3‐HP production (2.8 g/L) under shake‐flask conditions. When an aerobic fed‐batch process was carried out under bioreactor conditions at pH 7.0, the recombinant SH‐BGK1 produced 38.7 g 3‐HP/L with an average yield of 35%. This article reports the highest level of 3‐HP production from glycerol thus far. Biotechnol. Bioeng. 2009; 104: 729–739 © 2009 Wiley Periodicals, Inc.

Accurate and versatile modeling of electromagnetic scattering on periodic nanostructures with a surface integral approach

“…The same procedure can be repeated for Eqs. (36) and (37), which guarantees an accurate field evaluation close to the scatterer surface. If the discretized object completely fills the unit cell, the discretization mesh must be translation symmetric on opposite edges, in order to allow a continuity of the current flowing across the unit cell [ Fig.…”

“…Details about the implementation of Ewald's method for periodicities in one and three directions can be found in, e.g., [34][35][36], respectively. The area of the unit cell is ͉⍀͉ = ͉a 1 ϫ a 2 ͉.…”

“…The instantaneous scattered electric field is computed from Eqs. (36) and (37) and compared to the analytical solution for a plane wave in vacuum at normal incidence. In Fig.…”

Scattering on plasmonic nanostructures arrays modeled with a surface integral formulation

“…The first part of this section generalizes this formulation to periodic systems, and shows that the EFIE and MFIE are restricted to the unit cell with periodic boundary conditions. The EFIE and MFIE involve the pseudo-periodic dyadic Green's function, whose evaluation can be accelerated with Ewald's method [19,[22][23][24]. The MoM is used to discretize and solve the integral equations for the equivalent surface currents.…”

Artificial magnetism at terahertz frequencies from three-dimensional lattices of TiO_2 microspheres accounting for spatial dispersion and magnetoelectric coupling

“…(14) of [6], that expresses the interaction between the reference microsphere and the field produced by the other microspheres in the array. In other words, the termC int ω; k is the dyadic Green's function for the periodic array of dipoles regularized in both the space and spectral domains and is evaluated, for fast convergence, through the Ewald method [14,23,[28][29][30]. Two bars on top of a bold letter indicate a dyadic quantity.…”