Lundwise9330

Disorder components in surface anchoring orientation of a smectic-A liquid crystalline film (occurring, e.g., due to surface contamination sources) modify the thermal pseudo-Casimir interaction mediated between the bounding surfaces of the film. By considering a plane-parallel slab with bounding surfaces positioned normal to the layering field of the film, we study the anchoring disorder effects by assuming that the disorder source is present on one of the two substrates, producing a Gaussian-weighted distribution for the preferred molecular anchoring orientation (easy axis) on that substrate, with a finite mean and variance or, more generally, with a homogeneous in-plane, twopoint correlation function. We show that the presence of disorder, either of quenched or annealed type, leads to a significant reduction in the magnitude of the net pseudo-Casimir force between the confining substrates of the film. This force can be attractive or repulsive depending on the boundary conditions. In the quenched case, the interaction force reduction is a direct consequence of an additive free energy term dependent on the variance of the disorder, while in the annealed case, the suppression of the interaction force can be understood based on a disorder-renormalized, effective anchoring strength. We predict a regime of behavior, exhibiting non-monotonic dependence for the interaction pressure as a function of separation. We also show that, by increasing the disorder variance, the interaction pressure changes sign and becomes a monotonically decreasing function of the separation between the substrates. © 2020 IOP Publishing Ltd.The development of artificial photosynthetic systems is of great significance,which converts solar energy to fuels by photocatalytic water splitting or CO2 photoreduction. This review highlights recent advances in 3D structural artificial photosynthetic systems. First the review introduces three typical mechanisms for improved artificial photosynthesis improved light harvesting, mass transfer and charge separation. Next, it introduces typical state-of-the-art examples of the design and preparation of 3D structural artificial photosynthetic systems, including bioinspired design, photonic crystals, designed photonic structures, 3D printing, 3D nanowire integrated systems and hierarchical 3D structures. DW71177 Finally, main challenges and prospects are discussed, and possible trends for further development and optimization are given. We hope this review can inspire more progress in the field of artificial photosynthesis. © 2020 IOP Publishing Ltd.The mechanical behavior of vertically aligned carbon nanotube (VACNT) arrays can largely impact their adhesion performance. In this paper, we fabricated various VACNT arrays to investigate the relationship between adhesion force and their mechanical behavior. High-volume fraction (3.4%) CNT arrays did not exhibit the applicable adhesion effect due to their intrinsic elastic property. Adhesion measurements on several low-density (less than 0.5%) VACNT arrays demonstrated that the adhesion performance is strongly related to the plastic deformation of the carbon nanotubes at the contact surface. Due to the nature of the growth of CNT arrays, the top region of the as-grown CNT arrays is denser and stiffer than the bottom region of the arrays. Therefore, compared with as-grown CNT arrays, the flipped CNT arrays reached higher adhesion efficiency (the ratio of adhesion force to preload) with lower preload due to the higher compliance at the top surface of the arrays. With cyclic loading under micro mechanical tests, stiffening of the surface and declining of adhesion force were also observed. These results illustrated that the mechanical compliance at the region near the contact interface is the dominant factor for the adhesion performance of VACNT arrays. © 2020 IOP Publishing Ltd.OBJECTIVE Event-related potentials (ERPs) evoked by visual stimulations comprise several components, with different amplitudes and latencies. Among them, the N2 and N2pc components have been demonstrated to be a measure of subjects' allocation of visual attention to possible targets and to be involved in the suppression of irrelevant items. Unfortunately, the N2 and N2pc components have smaller amplitudes compared with those of the background electroencephalogram (EEG), and their measurement requires employing techniques such as conventional averaging (CA), which in turn necessitates several sweeps to provide acceptable estimates. In visual search studies, the number of sweeps (Nswp) used to extrapolate reliable estimates of N2/N2pc components has always been somehow arbitrary, with studies using 50 to 500 sweeps. In-silico studies relying on synthetic data providing a close-to-realistic fit to the variability of the visual N2 component and background EEG signals are therefore needed to go beyond arbitrary ched potential modulations. © 2020 IOP Publishing Ltd.We study the relaxation dynamics of non-equilibrium chirality distributions of charge carriers in Rashba systems. We find that at low temperature inter-Rashba band transitions become suppressed due to the combined effect of the Rashba momentum split and the chiral spin texture of a Rashba system. Specifically, we show that momentum exchange between carriers and the phonon bath is effectively absent at temperatures where the momentum of thermal phonons is less than twice the Rashba momentum. This allows us to identify inter-carrier scattering as the dominant process by which non-equilibrium chirality distributions relax. We show that the magnitude of inter-carrier scattering is strongly influenced by the opposing spin structure of the Rashba bands. Finally, we provide an explicit result for the inter-band relaxation timescale associated with inter-carrier Coulomb scattering. We develop a general framework and assess its implications for GeTe, a bulk Rashba semiconductor with a strong Rashba momentum split. Creative Commons Attribution license.A number of topological nodes including Dirac, quadratic and three-band touching points as well as a pair of degenerate Dirac line nodes are found to emerge in the triplet plaquette excitations of the frustrated spin-1/2 $J_1$-$J_2$ antiferromagnetic Heisenberg honeycomb model when the ground state of the system lies in a spin-disordered plaquette-valence-bond-solid phase. A six-spin plaquette operator theory of this honeycomb model has been developed for this purpose by using the eigenstates of an isolated Heisenberg hexagonal plaquette. Spin-1/2 operators are thus expressed in the Fock space spanned by the plaquette operators those are obtained in terms of exact analytic form of eigenstates for a single frustrated Heisenberg hexagon. Ultimately, an effective interacting boson model of this system is obtained on the basis of low energy singlets and triplets plaquette operators by employing a mean-field approximation. The values of ground state energy and spin gap of this system have been estimated and the validity of this formalism has been tested upon comparison with the known results.