Water is characterized by large molecular electric dipole moments and strong interactions between molecules; however, hydrogen bonds screen the dipole-dipole coupling and suppress the ferroelectric ...order. The situation changes drastically when water is confined: in this case ordering of the molecular dipoles has been predicted, but never unambiguously detected experimentally. In the present study we place separate H
O molecules in the structural channels of a beryl single crystal so that they are located far enough to prevent hydrogen bonding, but close enough to keep the dipole-dipole interaction, resulting in incipient ferroelectricity in the water molecular subsystem. We observe a ferroelectric soft mode that causes Curie-Weiss behaviour of the static permittivity, which saturates below 10 K due to quantum fluctuations. The ferroelectricity of water molecules may play a key role in the functioning of biological systems and find applications in fuel and memory cells, light emitters and other nanoscale electronic devices.
Intermolecular hydrogen bonds impede long-range (anti-)ferroelectric order of water. We confine H
O molecules in nanosized cages formed by ions of a dielectric crystal. Arranging them in channels at ...a distance of ~5 Å with an interchannel separation of ~10 Å prevents the formation of hydrogen networks while electric dipole-dipole interactions remain effective. Here, we present measurements of the temperature-dependent dielectric permittivity, pyrocurrent, electric polarization and specific heat that indicate an order-disorder ferroelectric phase transition at T
≈ 3 K in the water dipolar lattice. Ab initio molecular dynamics and classical Monte Carlo simulations reveal that at low temperatures the water molecules form ferroelectric domains in the ab-plane that order antiferroelectrically along the channel direction. This way we achieve the long-standing goal of arranging water molecules in polar order. This is not only of high relevance in various natural systems but might open an avenue towards future applications in biocompatible nanoelectronics.
The chiral vortical effect (CVE) was derived first for massless fermions, within the framework of thermal quantum field theory. Recently, a dual description of the CVE, as related to the radiation ...from the horizon of a rotating black hole was suggested. Generalizing the latter approach to the case of photons, we encounter a crucial factor-of-2 difference from the predictions based on the thermal field theory. To elucidate the reason for this discrepancy, we turn to the limit of large spin S of the massless particles. Within the gravitational approach, the CVE grows as S3, while the flat-space relations result in a dependence which is linear in S . We also discuss briefly an alternative formulation of the presumed duality between the statistical and gravitational approaches.
We study weighted altered Cesàro and Copson spaces, which are non-ideal enlargements of the usual Cesàro and Copson spaces. Full characterizations of their dual spaces are given.
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High resolution AFM distinguishes conformational states of single adsorbed proteins.Graphite induced protein denaturation is visualized at a single molecule level.Protein ...denaturation is accompanied by severe morphological changes.GM-HOPG more closely preserves the conformation of adsorbed proteins.
Different graphitic materials are either already used or believed to be advantageous in biomedical and biotechnological applications, e.g., as biomaterials or substrates for sensors. Most of these applications or associated important issues, such as biocompatibility, address the problem of adsorption of protein molecules and, in particular the conformational state of the adsorbed protein molecule on graphite. High-resolution AFM demonstrates highly oriented pyrolytic graphite (HOPG) induced denaturation of four proteins of blood plasma, such as ferritin, fibrinogen, human serum albumin (HSA) and immunoglobulin G (IgG), at a single molecule level. Protein denaturation is accompanied by the decrease of the heights of protein globules and spreading of the denatured protein fraction on the surface. In contrast, the modification of HOPG with the amphiphilic oligoglycine-hydrocarbon derivative monolayer preserves the native-like conformation and provides even more mild conditions for the protein adsorption than typically used mica. Protein unfolding on HOPG may have universal character for ⿿soft⿿ globular proteins.
We consider the photonic vortical effect, i.e., the difference of the flows of left- and right-handed photons along the vector of angular velocity in rotating photonic medium. Two alternative ...frameworks to evaluate the effect are considered, both of which have already been tried in the literature: first, the standard thermal field theory and, alternatively, Hawking-radiation-type derivation. In our earlier attempt to compare the two approaches, we found a crucial factor of 2 difference. Here, we revisit the problem, paying more attention to details of infrared regularizations. We find out that introduction of an infinitesimal mass of the vector field brings the two ways of evaluating the chiral vortical effect into agreement with each other. Some implications, on both the theoretical and phenomenological sides, are mentioned.
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The hydrodynamic coefficients in the axial current are calculated on the basis of the equilibrium quantum statistical density operator in the third order of perturbation theory in thermal ...vorticity tensor both for the case of massive and massless fermions. The coefficients obtained describe third-order corrections to the Chiral Vortical Effect and include the contribution from local acceleration. We show that the methods of the Wigner function and the statistical density operator lead to the same result for an axial current in describing effects associated only with vorticity when the local acceleration is zero, but differ in describing mixed effects for which both acceleration and vorticity are significant simultaneously.
O-antigens of Gram-negative bacteria modulate the interactions of bacterial cells with diverse external factors, including the components of the immune system and bacteriophages. Some phages need to ...acquire specific adhesins to overcome the O-antigen layer. For other phages, O-antigen is required for phage infection. In this case, interaction of phage receptor binding proteins coupled with enzymatic degradation or modification of the O-antigen is followed by phage infection. Identification of the strategies used by newly isolated phages may be of importance in their consideration for various applications. Here we describe an approach based on screening for host LPS alterations caused by selection by bacteriophages. We describe an optimized LPS profiling procedure that is simple, rapid and suitable for mass screening of mutants. We demonstrate that the phage infection strategies identified using a set of engineered E. coli 4 s mutants with impaired or altered LPS synthesis are in good agreement with the results of simpler tests based on LPS profiling of phage-resistant spontaneous mutants.
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The Unruh effect has been investigated from the point of view of the quantum statistical Zubarev density operator in space with the Minkowski metric. Quantum corrections of the fourth order ...in acceleration to the energy-momentum tensor of real and complex scalar fields, and Dirac field are calculated. Both massless and massive fields are considered. The method for regularization of discovered infrared divergences for scalar fields is proposed. The calculated corrections make it possible to substantiate the Unruh effect from the point of view of the statistical approach, and to explicitly show its universality for various quantum field theories of massless and massive fields. The obtained results exactly coincide with the ones obtained earlier by calculation of the vacuum aver- age of energy-momentum tensor in a space with a conical singularity. Thus, the duality of two methods for describing an accelerated medium is substantiated. One may also speak about the emergence of geometry with conical singularity from thermodynamics. In particular, the polynomiality of the energy-momentum tensor and the absence of higher-order corrections in acceleration can be explicitly demonstrated.
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