Chiral Effect Research Articles

Chiral effects on radiation and energy loss in quark–gluon plasma

The emergent axion excitations in the quark–gluon plasma are generated by the sphaleron transitions. Their interactions with the photon and gluon fields are governed by the axion electro- and chromodynamics, respectively. We discuss the effect of the emergent axion on the photon production and energy loss in the quark–gluon plasma. In particular, we review the Chiral Cherenkov effect, and the impact of the chiral anomaly on bremsstrahlung.

Emerging Chirality and Moiré Dynamics in Twisted Layered Material Heterostructures.

Moiré superstructures arising at twisted 2D interfaces have recently attracted the attention of the scientific community due to exotic quantum states and unique mechanical and tribological behaviors that they exhibit. Here, we predict the emergence of chiral distortions in twisted layered interfaces of finite dimensions. This phenomenon originates in intricate interplay between interfacial interactions and contact boundary constraints. A metric termed the fractional chiral area is introduced to quantify the overall chirality of the moiré superstructure and to characterize its spatial distribution. Despite the equilibrium nature of the discovered energetic and structural chirality effects, they are shown to be manifested in the twisting dynamics of layered interfaces, which demonstrates a continuous transition from stick-slip to smooth rotation with no external trigger.

A Family of Twisted Chiral Engineered Inorganic Nanoarchitectures.

Chiral inorganic materials possess unique asymmetric properties that could significantly impact various fields. However, their practical application has been hindered by challenges in creating structurally robust chiral materials. We report the synthesis of well-defined chiral-shaped hollow cobalt oxide nanostructures, extendable to a family of chalcogenides including sulfide, selenide, and telluride through topological transformations. Taking chiral cobalt oxide nanostructures as a representative material, we demonstrate precise control over their chiral architectures, enabling fine-tuning of parameters, such as twist degrees, handedness, and compositions. These chiral nanostructures exhibit high spin selectivity effects that influence the electron transfer processes in catalytic reactions. Leveraging this spin-selective behavior, the chiral cobalt oxide nanoarchitectures demonstrate enhanced electrocatalytic performance in the oxygen evolution reaction compared to their achiral counterparts. Our findings not only expand the library of chiral inorganic materials but also advance the application of chiral effects in fields such as catalysis, spintronics, and beyond.

Non-perturbative suppression of Chiral Effects in hot QGP for Λ/Λ̄-hyperons spin polarization in heavy-ion collisions

Non-perturbative suppression of Chiral Effects in hot QGP for Λ/Λ̄-hyperons spin polarization in heavy-ion collisions

Electronic and Optical Properties of 2D Heterostructure Bilayers of Graphene, Borophene and 2D Boron Carbides from First Principles.

In the present work the atomic, electronic and optical properties of two-dimensional graphene, borophene, and boron carbide heterojunction bilayer systems (Graphene-BC3, Graphene-Borophene and Graphene-B4C3) as well as their constituent monolayers are investigated on the basis of first-principles calculations using the HSE06 hybrid functional. Our calculations show that while borophene is metallic, both monolayer BC3 and B4C3 are indirect semiconductors, with band-gaps of 1.822 eV and 2.381 eV as obtained using HSE06. The Graphene-BC3 and Graphene-B4C3 bilayer heterojunction systems maintain the Dirac point-like character of graphene at the K-point with the opening of a very small gap (20-50 meV) and are essentially semi-metals, while Graphene-Borophene is metallic. All bilayer heterostructure systems possess absorbance in the visible region where the resonance frequency and resonance absorption peak intensity vary between structures. Remarkably, all heterojunctions support plasmons within the range 16.5-18.5 eV, while Graphene-B4C3 and Graphene-Borophene exhibit a π-type plasmon within the region 4-6 eV, with the latter possessing an additional plasmon at the lower energy of 1.5-3 eV. The dielectric tensor for Graphene-B4C3 exhibits complex off-diagonal elements due to the lower P3 space group symmetry indicating it has anisotropic dielectric properties and could exhibit optically active (chiral) effects. Our study shows that the two-dimensional heterostructures have desirable optical properties broadening the potential applications of the constituent monolayers.

First Hitting Times on a Quantum Computer: Tracking vs. Local Monitoring, Topological Effects, and Dark States.

We investigate a quantum walk on a ring represented by a directed triangle graph with complex edge weights and monitored at a constant rate until the quantum walker is detected. To this end, the first hitting time statistics are recorded using unitary dynamics interspersed stroboscopically by measurements, which are implemented on IBM quantum computers with a midcircuit readout option. Unlike classical hitting times, the statistical aspect of the problem depends on the way we construct the measured path, an effect that we quantify experimentally. First, we experimentally verify the theoretical prediction that the mean return time to a target state is quantized, with abrupt discontinuities found for specific sampling times and other control parameters, which has a well-known topological interpretation. Second, depending on the initial state, system parameters, and measurement protocol, the detection probability can be less than one or even zero, which is related to dark-state physics. Both return-time quantization and the appearance of the dark states are related to degeneracies in the eigenvalues of the unitary time evolution operator. We conclude that, for the IBM quantum computer under study, the first hitting times of monitored quantum walks are resilient to noise. However, a finite number of measurements leads to broadening effects, which modify the topological quantization and chiral effects of the asymptotic theory with an infinite number of measurements.

Plane dilatational and shear waves in a chiral porous thermoelastic medium under strain gradient theory

Purpose This study aims to investigate time-harmonic wave propagation in a chiral porous thermoelastic solid under strain gradient theory (SGT), focusing on identifying and characterizing distinct wave modes within the medium. Design/methodology/approach Using Iesan's gradient theory, which incorporates chiral effects and accommodates second sound phenomena, the authors derive mathematical formulations for the velocities and attenuations of eight propagating waves: four dilatational waves and two pairs of coupled shear waves (one left circularly polarized, the other right). Numerical simulations are performed for a specific model, exploring the influence of various parameters on wave propagation. Findings The authors establish that the medium supports four dilatational waves, including a microstretch-associated wave, and four shear waves, distinguished by their chiral-induced characteristics. The results highlight the frequency-dependent dispersive nature of all propagating waves and establish connections with existing theoretical frameworks, demonstrating the broader applicability of our findings. Practical implications The characteristics of wave propagation in chiral media examined here can enhance our understanding of chiral medium behavior. This knowledge is crucial for developing materials with pronounced chiral effects, surpassing those found in natural chiral materials like bone, quartz, sugar and wood. Advances in artificial chiral materials are driven by their superior toughness, durability and other beneficial properties. Consequently, this study has potential applications across various fields, including the design of chiral broadband absorbers and filters, the production of artificial bones and medical devices, aeronautical engineering and beyond. Originality/value This research extends existing theories and deepens the understanding by exploring wave behaviors in chiral media, advancing this emerging field.

Experimental encircling of an exceptional point in a two degrees of freedom system: overview and application to noise control

When a resonator is added to an acoustic cavity or a vibrating structure, a new resonance frequency, or pole, is created in the system. When dissipation is present, this may breakdown when some parameters are finely tuned. This phenomenon, typical of non-Hermitian dynamics is called an exceptional point in the parametric space where two (or more) eigenvalues, as well as their associated eigenvectors, coalesce. In the recent years, EPs have gained interest in physics because of the counter-intuitive concepts associated with them. In the fields of acoustics and vibration, understanding EP may lead to a better comprehension of modal energy exchanges and decay. This work aims at exploring the key concepts related to EPs by revisiting the well-known coupled pendulums problem in the presence of damping. First, the free response of the experimental system is investigated after tuning it on an EP. Then an encircling is performed by varying the parameters through time. Our experimental results illustrate in a pedagogical manner nearly-optimal dissipation, energy exchange and chirality effects which have been recently evidenced in physics.

One-Pot Synthesis of Chiral Cysteine-Capped Gold Nanoparticles for Use as Vaccine Adjuvants in Mice

The influence of chirality on the biological activity of nanoparticles, including their interaction with the immune system, is a growing area of interest. This study presents a one-pot synthesis method for 15 nm L-cysteine or D-cysteine capped gold nanoparticles (L/D-Cys-GNPs) and evaluates their immunological potential as adjuvants in mice. The synthesized GNPs were comprehensively characterized using UV-visible absorption spectroscopy, FTIR, CD spectra, and TEM, revealing enhanced stability and effective internalization by human umbilical vein endothelial cells (HUVEC), with L-Cys-GNPs exhibiting a higher uptake rate. In vivo immunization studies demonstrated that L-Cys-GNPs significantly boosted the production of anti-ovalbumin(OVA) IgG antibodies compared to D-Cys-GNPs (>66 folds), underscoring the importance of chiral surface properties in modulating immune responses. However, the encapsulation of GNPs in liposomes negated the chiral effect, suggesting that delivery methods may influence the interaction of GNPs with the immune system. The findings highlight the role of chirality in vaccine development and provide insights into targeted antigen delivery systems. This work contributes to the understanding of chirality in vaccine development and paves the way for the design of more effective vaccines against challenging diseases.

MODELING OF THE GEOMETRY AND ELECTRONIC BANDGAP STRUCTURE OF CHIRAL SINGLE WALLED CARBON NANOTUBES

Carbon Nanotubes (CNTs) are one-dimensional nanostructured materials that will play a key role in future electronics. All properties of the carbon nanotubes are determined by its electronic structure. The main focus of this study has been to investigate the basic electronic bandgap structure of the chiral single walled carbon nanotubes (SWCNTs). A simple algorithm is presented in order to model the geometry of the chiral single-walled CNTs with any desired structure. The electronic bandgap structure of the chiral single-walled carbon nanotubes has been studied by employing an extended tight binding model (TBM). The changes in the energy band gap due to the chirality effect in case of metallic (6, 3) SWCNT and in the semiconducting (12, 7) SWCNT are discussed here. The value of the SWCNTs diameter is calculated also. The computed results indicates that the bandgap depends inversely on the diameter of the tube. The present results were found to be in consistent with those reported in the literature and indicated the correctness of the process of simulation technique process.

Curved Nanointerface Controls the Chiral Effect on Peptide Fibrillation.

Nanostructures with varying functionalities have been engineered to modulate the fibrillation of amyloid-β (Aβ) peptides. Nevertheless, the chirality effect at the curved nanointerfaces is seldom dissected. In this study, we systematically explored the curvature-modulated chiral effect on the regulation of Aβ1-42 fibrillation by using l/d-penicillamine-gold nanoparticles (l/d-PGNPs). According to the microscopic and spectroscopic analyses, Aβ1-42 fibrillation can be effectively suppressed by more curved (0.2 nm-1, 1/r) d-nanointerface (d-PGNPs5) with notable chiral selectivity, even at a low inhibitor/peptide (I/P) molar ratio (1:100). A greatly alleviated cytotoxic effect of Aβ1-42 peptides after the inhibition process is also revealed. The highly curved nanointerface drives the formation of multiple hydrogen bonds and promotes electrostatic interactions with Aβ1-42. Importantly, the curved d-nanointerface controls well the spatial arrangement of Pen motifs, making it incompatible with the fibrillation direction of Aβ1-42 and thus gaining enhanced efficiency on amyloid fibrillar modulation. This study provides valuable insights into the interactions between chirality and peptide-nanointerface effects, which are crucial for the development of inhibitors in anti-β-amyloidosis.

Stereoselective Synthesis of Maralixibat via VO(acac)2/Schiff Base-Catalyzed Asymmetric Oxidation of Its Sulfide Intermediate.

The stereoselective synthesis of maralixibat was achieved by harnessing the chiral transferring effect of the stereogenic R-sulfoxide functionality, which was obtained via the VO(acac)2/Schiff base-catalyzed asymmetric oxidation of a phenylthiophenol prochiral intermediate. The R-sulfoxide intermediate underwent a ring closure reaction to form the seven-membered ring core structure with the desired stereochemistry, ultimately ensuring the drug's exceptional isomeric purity and synthetic efficiency.

Exploring the Effects of Chirality of 5-methyl-5-[4-(4-oxo-3H-quinazolin-2-yl) phenyl]imidazolidine-2,4-dione and its Derivatives on the Oncological Target Tankyrase 2. Atomistic Insights.

Tankyrases (TNKS) are homomultimers existing in two forms, viz. TNKS1 and TNKS2. TNKS2 plays a pivotal role in carcinogenesis by activating the Wnt//β-catenin pathway. TNKS2 has been identified as a suitable target in oncology due to its crucial role in mediating tumour progression. The discovery of 5-methyl-5-[4-(4-oxo-3H-quinazolin-2-yl) phenyl] imidazolidine-2,4-dione, a hydantoin phenylquinazolinone derivative which exists as a racemic mixture and in its pure enantiomer forms, has reportedly exhibited inhibitory potency towards TNKS2. However, the molecular events surrounding its chirality towards TNKS2 remain unresolved. Herein, we employed in silico methods such as molecular dynamics simulation coupled with binding free energy estimations to explore the mechanistic activity of the racemic inhibitor and its enantiomer forms on TNK2 at a molecular level Results: Favourable binding free energies were noted for all three ligands propelled by electrostatic and van der Waals forces. The positive enantiomer demonstrated the highest total binding free energy (-38.15 kcal/mol), exhibiting a more potent binding affinity to TNKS2. Amino acids PHE1035, ALA1038, and HIS1048; PHE1035, HIS1048 and ILE1039; and TYR1060, SER1033 and ILE1059 were identified as key drivers of TNKS2 inhibition for all three inhibitors, characterized by the contribution of highest residual energies and the formation of crucial high-affinity interactions with the bound inhibitors. Further assessment of chirality by the inhibitors revealed a stabilizing effect of the complex systems of all three inhibitors on the TNKS2 structure. Concerning flexibility and mobility, the racemic inhibitor and negative enantiomer revealed a more rigid structure when bound to TNKS2, which could potentiate biological activity interference. The positive enantiomer, however, displayed much more elasticity and flexibility when bound to TNKS2. Overall, 5-methyl-5-[4-(4-oxo-3H-quinazolin-2-yl) phenyl] imidazolidine-2,4-dione and its derivatives showed their inhibitory prowess when bound to the TNKS2 target via in silico assessment. Thus, results from this study offer insight into chirality and the possibility of adjustments of the enantiomer ratio to promote greater inhibitory results. These results could also offer insight into lead optimization to enhance inhibitory effects.

Nonreciprocal polarized transmission via bound states in the continuum.

We realize the observation of near-unity nonreciprocal polarized transmission via the bound states in the continuum (BICs) in a double-layer grating structure. By introducing out-of-plane perturbations and topological defects that break the mirror symmetry between the upper and lower layers, the far-field polarization states in momentum space are inverted vertically and horizontally, showing mirrored polarization characteristics for incident channels from different upper and lower ports. During the process of introducing mirror perturbations in the upper and lower layers, a π/2 phase inversion occurs in the Г-M direction, making chirality possible. Utilizing this bidirectionally tunable nonreciprocal spatiotemporal phase transition enables multiple modulations of polarization states and opens up more possibilities for asymmetric light manipulation in chiral optical effects.

Torsional vibration suppression of a gear-rotor system using an inerter magnet nonlinear energy sink

The novel inerter magnet nonlinear energy sink (IMNES) utilizes chiral compression-torsion coupling effects to achieve mass augmentation, effectively mitigating torsional vibrations in a gear-rotor system with gear meshing clearance. The positive stiffness generated by the piecewise linear beam combines with the negative stiffness produced by the permanent magnet pair, resulting in the establishment of the IMNES’s nonlinear stiffness. Subsequently, a dynamic model of the IMNES-gear-rotor system is developed. Optimal parameters for the IMNES are determined through analysis of vibrational response surfaces under both transient and steady-state conditions. The numerical calculation of torsional vibration in the IMNES-gear rotor system is conducted across various gear meshing clearances. The results demonstrate that across different gear mesh clearances, the IMNES effectively attenuates torsional vibrations in the gear-rotor system. Under transient excitation, implementation of the IMNES leads to an 87% reduction rate in displacement within the gear-rotor system. In terms of steady-state excitation, simulations show a significant enhancement with a 65% increase in vibration suppression percentage.

Manipulation of Magnonic Activity by Electric Currents in Ferromagnetic Nanocylinders

Electric currents passing through ferromagnets can impact the magnetization dynamics via the so-called spin-transfer torque (STT) effect. In this paper, we present a theoretical study on the current influence on magnonic activity, a recently reported spin wave (SW) chiral effect in ferromagnetic nanotubes. By micromagnetic simulations, we show that an electric current can cause a significant change in the rotatory power of the SW modes propagating in a longitudinally magnetized nanotube. This result is well explained by using the Fresnel model in optics assuming a SW circular birefringence. An analytical method is developed to solve the first-order mode, yielding perfect agreements with the numerical results. Our results provide a new approach to manipulate the SW propagating properties in ferromagnetic nanocylinders.

Anomalous Nernst effect in the noncollinear antiferromagnet Mn5Si3

Investigating the off-diagonal components of the conductivity and thermoelectric tensor of materials hosting complex antiferromagnetic structures has become a viable method to reveal the effects of topology and chirality on the electronic transport in these systems. In this respect, Mn5Si3 is an interesting metallic compound that exhibits several antiferromagnetic phases below 100 K with different collinear and noncollinear arrangements of Mn magnetic moments determined from neutron scattering. Previous electronic transport measurements have shown that the transitions between the various phases give rise to large changes of the anomalous Hall effect. Here, we report measurements of the anomalous Nernst effect of Mn5Si3 single crystals that also show clear transitions between the different magnetic phases. In the noncollinear phase, we observe an unusual sign change of the zero-field Nernst signal with a concomitant decrease of the Hall signal and a gradual reduction of the remanent magnetization. Furthermore, a symmetry analysis of the proposed magnetic structures shows that both effects should actually vanish. These results indicate a symmetry-breaking modification of the magnetic state with a rearrangement of the magnetic moments at low temperatures, thus questioning the previously reported models for the noncollinear magnetic structure obtained from neutron scattering.

Chiral Effect on the Spin Crossover Behavior in a Pair of Co(II) Enantiomers and their Racemic Complex

Chiral Effect on the Spin Crossover Behavior in a Pair of Co(II) Enantiomers and their Racemic Complex

Next-to-next-to-leading order evolution of polarized parton densities in the Larin scheme

In many calculations involving polarized twist-2 parton densities to higher order in the strong coupling constant one uses the Larin scheme to describe chiral effects in dimensional regularization. Upon forming observables, the scheme dependence cancels. Still one needs a corresponding regularization scheme to compute the contributing building blocks, like massless and massive Wilson coefficients, as well as the massive three-loop operator matrix elements used in the variable flavor number scheme. These are matched to the evolved parton distribution functions in the Larin scheme. Starting with suitable input distributions we provide the solution of scale evolution of the different polarized parton distribution functions in Bjorken x space for a wide range of virtualities Q2 in the Larin scheme, at next-to-leading, at next-to-next-to-leading order for the first time. We also illustrate the deviation between the parton distributions in the Larin and MS¯ schemes numerically. Published by the American Physical Society 2024

Magneto-optical chiral metasurfaces for achieving polarization-independent nonreciprocal transmission.

Nonreciprocal transmission, resulting from the breaking of Lorentz reciprocity, plays a pivotal role in nonreciprocal communication systems by enabling asymmetric forward and backward propagations. Metasurfaces endowed with nonreciprocity represent a compact and facile platform for manipulating electromagnetic waves in an unprecedented manner. However, most passive metasurfaces that achieve nonreciprocal transmissions are polarization dependent. While incorporation of active elements or nonlinear materials can achieve polarization-independent nonreciprocal metasurfaces, the complicated configurations limit their practical applications. To address this issue, we propose and demonstrate a passive and linear metasurface that combines magneto-optical and chiral effects, enabling polarization-independent isolation. The designed metasurface achieves a transmittance of up to 80%, with a high contrast between forward and backward propagations. Our work introduces a novel mechanism for nonreciprocal transmission and lays the foundation for the development of compact, polarization-insensitive nonreciprocal devices.