Unveiling the Effects of In Situ Layer–Layer Interfacial Reaction in Multilayer Polymer Films via Multilayered Assembly: From Microlayers to Nanolayers

Multilayered polymer films are increasingly used in the daily life, but their macroscopic properties are always limited by the layer–layer interfacial compatibility. In this work, the influence of interface modification through in situ layer–layer interfacial reaction during a multilayered assembly is revealed from micro‐ to nanolayer films, based on maleated poly(vinylidene fluoride) and polyamide‐6. In the presence of interfacial reaction and confinement, layer architecture and microstructure are highly dependent on the number of layers. Specifically, for nanolayer films having smaller layer thicknesses and higher reaction extent, layer integrity is reduced with the occurrence of interfacial instabilities. Depending on the microstructural evolution from multilayer assembly, those films exhibit quantitatively different extensional rheological and dielectric properties from micro‐ to nanolayers. More importantly, dielectric spectroscopy reveals the contribution of copolymer‐rich interphases to the dielectric performance of micro/nanolayered films. Additionally, charge transport dynamics in nanolayered films also differ significantly from their microlayered counterparts. They are attributed to the strong dependence of interfacial reaction extent and resulting microstructure on the number of layers and layer thicknesses. This work clearly illustrates how the control of layer–layer interfacial reaction in micro/nanolayer assembly can tune the interfacial, microstructure, and macroscopic properties of multilayered products.     

Genetic interactions of yeast NEP1 (EMG1), encoding an essential factor in ribosome biogenesis

Nep1 methylates the hypermodified ψ1191 base of 18S rRNA and has an additional essential function during ribosome biogenesis. It is strongly conserved in eukaryotes and a point mutation causes the human Bowen-Conradi syndrome. To identify Δnep1-specific genetic interactions, viable deletions were screened genome-wide (SGA). Due to its essential function, we used, for the first time, query strain (Δnep1) with two additive suppressor conditions (mcRPS19B, nop6-1). Nep1 interacting genes correspond to ribosome biogenesis (RPS18A, RPS18B, RRP8, EFG1, UTP30), to ribosome quality control (UBP3, BRE5, UBP6) and to ribosome functional control (DOM34, no-go decay). Deletions in ribosome quality and functional control genes were synthetically sick with Δnep1. They cope with malfunctions and the respective deletions strengthen the Δnep1 growth deficiency. Except for Δrps18b, deletions in the identified ribosome biogenesis genes were synthetically lethal with Δnep1. While the synthetic lethalities of Δrrp8 and Δefg1 may result from additive defects, the Δutp30 deletion seems to be in close functional relationship. The Δutp30 deletion itself has no phenotype but it enforced all nep1-1(ts) mutant phenotypes. Furthermore, its overexpression partially restored the nep1-1(ts) growth deficiency. Our genetic and biochemical data suggest that Utp30 and Nep1 act together during pre-ribosomal complex formation and, along with Rps18, provide the surface for the Rps19 assembly to the 90S pre-ribosome.     

Density Fluctuations and Phase Transitions of Ferroelectric Polymer Nanowires

Phase transitions of polymeric materials are accompanied by changes in density as a function of temperature. Being able to measure these changes in polymeric systems in one, two or three dimensions on the nanoscopic length‐scale is a challenge, but it would provide a simple route to assess phase transitions in nanoscopically confined systems. It is shown that the measurement of the dielectric permittivity in the high frequency limit (in spectral regions not affected by dielectric dispersions) offers an effective and very sensitive means to assess density fluctuations, and hence phase transitions, in nanoscopic systems. The sensitivity of this approach is demonstrated by assessing the phase transition behavior of ferroelectric polymer nanowires confined within alumina membranes. No significant shifts in the Curie transition are observed down to pore diameters as small as 15 nm.     

Dielectric properties of liquid crystals for display and sensor applications

Temperature dependence of dielectric properties of nematic liquid crystals are investigated for two types of devices: wide temperature range liquid crystal (LC) displays and capacitor temperature sensor. Both real and imaginary components of the dielectric constant have been measured in wide frequency and temperature range including t < 0 °C as well as versus the angle θ between the directions of both magnetic and electric field in the measuring scheme. Some physical parameters of the nematic LC (NLC) dielectric relaxation have been determined. Effective values of the LC dielectric permittivity with different values of the LC pretilt angles in different parts of a complex LC cell have been simulated.     

Decay of Supercurrents in Condensates in Optical Lattices

In this paper we discuss decay of superfluid currents in boson lattice systems due to quantum tunneling and thermal activation mechanisms. We derive asymptotic expressions for the decay rate near the critical current in two regimes, deep in the superfluid phase and close to the superfluid-Mott insulator transition. The broadening of the transition at the critical current due to these decay mechanisms is more pronounced at lower dimensions. We also find that the crossover temperature below which quantum decay dominates is experimentally accessible in most cases. Finally, we discuss the dynamics of the current decay and point out the difference between low and high currents.     

Switching between gamma and theta: Dynamic network control using subthreshold electric fields

We implemented an experimentally observed orthogonal arrangement of theta and gamma generation circuitry in septotemporal and lamellar dimensions is a two-dimensional model of hippocampus. The model includes three types of cells: pyramidal, basket, and oriens lacunosum-moleculare (OLM) neurons. In this reduced model, application of continuous electric fields allowed us to switch between theta, gamma and mixed theta-gamma regimes without additional pharmacological manipulation. Electric field effects on individual neurons were modeled based on experimental data. Network simulation results predict a flexible experimental technique, which would employ adaptive subthreshold electric fields to continuously modulate neuronal ensemble activity, and can be used for testing cognitive correlates of oscillatory rhythms as well as for suppressing epileptiform activity.     

Nano and Giga Challenges in Electronics Photonics and Renewable Energy (NGC2011) Moscow-Zelenograd, Russia, September 12-16, 2011 Editorial article

ABSTRACT: This special issue of Nanoscale Research Letters is a collection of selected papers presented at the Nano and Giga Challenges in Electronics, Photonics and Renewable Energy (NGC2011) conference in Moscow and Zelenograd which addresses both theoretical and experimental achievements and provide a stimulating outlook for technological developments in these highly topical fields of research.     

V‐shaped electro‐optical mode based on deformed‐helix ferroelectric liquid crystal with subwavelength pitch

Abstract— V‐shaped electro‐optical response is shown, both theoretically and experimentally, to be an inherent property of a deformed‐helix ferroelectric liquid‐crystal cell (DHFLC) under a special choice of the applied rectangular alternating‐electric‐field waveform, frequency, and cell geometry. In contrast to other known V‐shaped ferroelectric liquid‐crystal (FLC) modes, the discovered V‐shaped switching is observed in a broadband frequency range including 1 kHz, and not at a certain characteristic frequency. This type of V‐shaped switching allows for a drastic increase in the operating frequency of field‐sequential‐color (FSC) LCD cells in comparison with fast nematic liquid‐crystal (NLC) modes.