Chiral Torsion Research Articles

Supersymmetric States in Anti-de Sitter D=3 Supergravity with Chiral Torsion.

In this Letter, we construct a supersymmetric model, obtained by deforming N=2 anti-de Sitter D=3 supergravity through a chiral vector component of the torsion. Moreover, we study the existence of supersymmetric states of such theory by inspecting the presence of Killing spinors on a specific bosonic solution.

Monolayer heterojunction interactive hydrogels for high-freedom 4D shape reconfiguration by two-photon polymerization.

Mimicking natural botanical/zoological systems has revolutionarily inspired four-dimensional (4D) hydrogel robotics, interactive actuators/machines, automatic biomedical devices, and self-adaptive photonics. The controllable high-freedom shape reconfiguration holds the key to satisfying the ever-increasing demands. However, miniaturized biocompatible 4D hydrogels remain rigorously stifled due to current approach/material limits. In this research, we spatiotemporally program micro/nano (μ/n) hydrogels through a heterojunction geometric strategy in femtosecond laser direct writing (fsLDW). Polyethylene incorporated N-isopropylacrylamide as programmable interactive materials here. Dynamic chiral torsion, site-specific mutation, anisotropic deformation, selective structural coloration of hydrogel nanowire, and spontaneous self-repairing as reusable μ/n robotics were identified. Hydrogel-materialized monolayer nanowires operate as the most fundamental block at nanometric accuracy to promise high freedom reconfiguration and high force-to-weight ratio/bending curvature under tight topological control. Taking use of this biomimetic fsLDW, we spatiotemporally constructed several in/out-plane self-driven hydrogel grippers, diverse 2D-to-3D transforming from the same monolayer shape, responsive photonic crystal, and self-clenched fists at μ/n scale. Predictably, the geometry-modulable hydrogels would open new access to massively-reproducible robotics, actuators/sensors for microenvironments, or lab-on-chip devices.

Neutrino Oscillations Induced by Chiral Torsion

Neutrino Oscillations Induced by Chiral Torsion

3D-printed chiral torsion Janus evaporator with enhanced light utilization towards ultrafast and stable solar-water desalination

Solar evaporation is a sustainable, environmentally friendly and promising solution to the problem of fresh water shortage. However, the widespread application of solar evaporators is limited by their spatial geometry, surface salt deposition and durability. Here, a Janus evaporator with a 3D chiral torsion structure is designed using 3D printing technology. Such a structure increases the number of light reflections to improve light collection. At the same time, the top and bottom layers of the Janus evaporator are endowed with different surface wettability. In particular, the top layer of superhydrophobic SiO2/CNTs aerogel acts as a photothermal absorber and prevents salt deposition, while the bottom layer of superhydrophilic CNTs aerogel accelerates water replenishment and improves water transfer efficiency. At 1 sun, the 3D Janus evaporator exhibits a high evaporation rate of 2.775 kg m−2 h−1 and a solar-to-vapor conversion efficiency of 90.2%. The 3D Janus evaporator demonstrates a strong desalination capacity in simulated seawater and allows one to obtain fresh water above drinking water standards. Moreover, it can work sustainably in different environments and has good cycle stability. The 3D Janus evaporator, prepared by 3D printing, opens up new prospects and great potential to solve the issues associated with fresh water shortage.

Primordial magnetic walls decay and Debye screening from proca electrodynamics and chiral torsion

Primordial magnetic walls decay and Debye screening from proca electrodynamics and chiral torsion

Cosmological constant, axial anomalies and photon mass dynamos from chiral fermionic torsion

Motivated by Palle’s investigation on the handness of chirality of vorticity in Einstein–Cartan cosmology [Entropy 5 (2014)], several aspects of chiral torsional handness in magnetogenesis and cosmology are presented. In the first one, we obtain torsion bounds from massive photons and axial anomalies. In the second, we deal with magnetogenesis from photon mass and in the third, we discuss chiral torsion degrees of freedom to obtain a torsion cosmological constant dependent solution. The torsion solution decays fast and implies a strong suppression of torsion at present universe. Our result contains the Poplawski [Phys. Lett. B (2010)] results in the case axial torsion vector associated to Einstein–Cartan fermionic sector matter and conformal anomalies of quarks. In the third example, a magnetic field bound from chiral torsionic dynamos is obtained as [Formula: see text]. In the non-minimal cosmological models, chiral dynamos are sourced by massive photons, London currents and chiral magnetic effect (CME). Chiral chemical potential is found to be mimic by torsion. Cosmological constant bound [Formula: see text] is found. At the early universe, the cosmological constant [Formula: see text] is obtained. Torsion used in the present universe is [Formula: see text]. In the last and fourth example, chiral anisotropic currents are obtained and magnetic helicity is shown to depend upon torsion when the chiral chemical potential is non-constant.

A novel mechanical metamaterial with tailorable Poisson’s ratio and thermal expansion based on a chiral torsion unit

Auxetic and negative thermal expansion metamaterials have a wide range of applications in flexible electronics, aerospace, biomedicine. Based on the compression/thermal–torsion coupling effects, and combining the special deformation mechanism of the planar anti-tetrachiral structure, this work proposed a novel 3D mechanical metamaterial with negative Poisson’s ratio (PR) and negative coefficient of thermal expansion. The mechanical design method of the metamaterial is demonstrated, and the coordinated deformation theory between its in-plane and out-of-plane deformations is established. By numerical simulation, the torsional deformation response of torsion unit of the metamaterials is explored, and Poisson’s characteristics and thermal expansion effect of the metamaterials are analyzed. The results show that the PR and thermal expansion effect of the metamaterial can be adjusted and switched, and its deformation behavior can be programmed. The coupling design method for metamaterials provides a good design strategy for engineering applications such as intelligent actuators, flexible robots, and biomedical sensors.

Einstein–Cartan non-supersymmetric spin-polarised nucleons wall dynamos

Einstein-Cartan (EC) gravity uses as source a spin–spin torsion contact interaction. In this paper we make use EC QCD domain walls with nucleons spins, orthogonally to the wall, as an EC chiral torsion source to investigate magnetogenesis. Dynamo amplification factor of γEU∼10−3GeV is obtained from Early universe torsion of 1 MeV. Early universe torsion and QCD topology also provide us with an estimate of magnetic helicity density of hQCD∼1034G210−3GeV. In this case, helicity in the presence of torsion is stronger than in Minkowskian spacetime. Chiral chemical potential undergoes torsion effects as well, and not only of the Hubble constant. QCD domain wall non-supersymmetric metrics [Jensen, Soleng, CQG (1998)] and Garcia de Andrade (1999), are shown to lead to exact solution of chiral dynamo equations with magnetic fields parallel to the wall due to the chiral magnetic effect (CME). A special type of Einstein-Cartan chiral dynamo solution is found on a dilatonic domain wall, where when torsion vanishes the magnetic field is constant. In this domain wall metric exponents depend only upon torsion components.

Cyclohelminthol CPs: Scope and Limitations of Density Functional Theory-Based Structural Elucidation of Natural Products.

The effectiveness and limitations of density functional theory (DFT) calculations in the structural determination of complexed and conformationally flexible natural products were demonstrated using the cyclohelminthols CP-1 (1) CP-2 (2), CP-3 (3), and CP-4 (4) newly isolated from Helminthosporium velutinum yone96. Prior to DFT calculations, the structures were tentatively assigned using conventional spectroscopic analyses. The structures were verified with reference to DFT-derived 13C and 1H NMR chemical shifts, 3JHH and nJCH values, and electronic circular dichroism (ECD) spectra. The 13C chemical shift calculations were very effective for verifying the ring-structure moieties but less effective for verifying the geometry of the side chain in which the juncture asymmetric carbon (C-16) was apart from the ring-structure moiety. However, 1H chemical shift calculations compensated for the imperfection of the latter. ECD spectral calculations were used to determine the absolute configurations. Calculations for virtual simple model molecules enabled us to evaluate the reliability of the ECD spectral calculation and derive the chiral torsion responsible for the characteristic Cotton effects.

Synthesis, Stereochemistry and Ligating Properties of Tetraalkyl-Substituted Ethanedithioamides − Evidence for the Lowering of High-Energy Rotation Barriers under the trans Influence of Pt-σ-Bonded Aryl Groups

The structural and coordinating properties of five tetrasubstituted tetraalkyldithioxamides (R4DTO) have been studied: tetraethyldithioxamide (Et4DTO, 1), tetrabenzyldithioxamide (Bz4DTO, 2), (E,E)-N,N′-dibenzyl-N,N′-diethyldithioxamide [(E,E)-Bz2Et2DTO, 3], (E,Z)-N,N′-dibenzyl-N,N′-diethyldithioxamide [(E,Z)-Bz2Et2DTO, 4], (Z,Z)-N,N′-dibenzyl-N,N′-diethyldithioxamide [(Z,Z)-Bz2Et2DTO, 5]. The solid structure of 4, determined by single-crystal X-ray diffraction, is characterised by two planar thioamide groups positioned almost orthogonally to each other, connected by a C−C single bond. Each of these dithioxamides showed high-energy barriers to rotation around both the C−N and the central C−C bond. This latter is a chiral torsion, so that R4DTO species exist as pairs of enantiomers. Compounds 3, 4 and 5 slowly isomerised in solution to give equimolar mixtures of the three isomers; the activation enthalpy of the process was 30.0 kcal mol−1. The ligands 1−5 reacted with [Pt(Me2SO)2X2] (X = Cl, Br, Me, Ph) to give chiral chelate complexes [(R4DTO-κ-S,S′)PtX2], but 3 (and also 4 and 5) provided a mixture of three isomeric platinum chelates in which the S,S′-coordinated ligands showed the (E,E), (E,Z) and (Z,Z) conformations. Furthermore, the presence of small amounts of the platinum complexes cis-[Pt(Me2SO)2Ph2] or [(Et4DTO-κ-S,S′)PtPh2] caused the fast isomerisation of large quantities of a given isomerically pure ligand. We have explained the collapse of the R4DTO rotational barriers by assuming that a release of electrons from the metal atom to incoming ligands in the transition state twists these into a partially reduced, dithiolenic form. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Evidence for an unexpected chiral axis in tetraethyldithiooxamide and in its platinum(II) coordination and organometallic complexes.

Abstract Tetraethyldithioxamide (Et 4 -DTO) shows in solution high energy barriers either for chiral torsion around CC axis or for achiral torsion around CN axis. A chiral CC axis was also evidenced by a crystal structure determination on a single crystal, which showed clearly the right absolute configuration in the P4 3 space group. 1 H-NMR signals of the prochiral probe -C 2 H 5 in Et 4 -DTO provided unequivocal evidence for the persistence of the chiral CC axis also in co-ordination and organometallic complexes of platinum(II) of the chelate ligand Et 4 -DTO.

Circular dichroism of supercoiled DNA: the role of chiral torsion

The circular dichroism of supercoiled DNA has been calculated as a function of superhelix density using the exciton and free-electron models. The two models agree with each other, and with experiment, at large negative superhelix densities, but disagrees at lower superhelix densities. The reasons are discussed in terms of the role of chiral torsion.