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The spin-orbit interaction of light is a fundamental manifestation of controlling its angular momenta with numerous applications in photonic spin Hall effects and chiral quantum optics. However, observation of an optical spin Hall effect, which is normally very weak with subwavelength displacements, needs quantum weak measurements or sophisticated metasurfaces. Here, we theoretically and experimentally demonstrate the spin-orbit interaction of light in the form of strong chiroptical responses by breaking the in-plane inversion symmetry of a dielectric substrate. The chiroptical signal is observed at the boundary of a microdisk illuminated by circularly polarized vortex beams at normal incidence. The generated chiroptical spectra are tunable for different photonic orbital angular momenta and microdisk diameters. Our findings, correlating photonic spin-orbit interaction with chiroptical responses, may provide a route for exploiting optical information processing, enantioselective sensing, and chiral metrology.

The antibiotic crisis is associated with the appearance of multidrug resistant (MDR) pathogens, which has caused severe bacterial infections and imposed a huge burden on modern society. Therefore, there is an urgent need to develop new antibacterial drugs with novel mechanism of action. Here we designed and synthesized three series of benzoxazolone, oxazolopyridinone and 3-(2-hydroxyphenyl)hydantoin derivatives and evaluated their activity as novel quorum sensing (QS) inhibitors. We found that benzoxazolone and oxazolopyridinone derivatives had promising QS inhibitory activity in the minimum inhibitory concentration, pyocyanin and rhamnolipid inhibition assays. In particular, A10 and B20 at 256 μg/mL not only suppressed pyocyanin production regulated by QS in P. aeruginosa PAO1 by 36.55% and 46.90%, respectively, but also showed the strongest rhamnolipid inhibitory activity with the IC

Photons with spin angular momentum possess intrinsic chirality which underpins many phenomena including nonlinear optics1, quantum optics2, topological photonics3 and chiroptics4. Intrinsic chirality is weak in natural materials, and recent theoretical proposals5-7 aimed to enlarge circular dichroism by resonant metasurfaces supporting bound states in the continuum that enhance substantially chiral light-matter interaction. Those insightful works resort to three-dimensional sophisticated geometries, which are too challenging to be realized for optical frequencies8. Therefore, most of the experimental attempts9-11 showing strong circular dichroism rely on false/extrinsic chirality by employing either oblique incidence9, 10 or structural anisotropy11. Here, we report on the experimental realization of true/intrinsic chiral response with resonant metasurfaces where the engineered slant geometry breaks both in-plane and out-of-plane symmetries. Our result marks the first observation of intrinsic chiral bound states in the continuum with near-unity chiral dichroism of 0.93 and record-high quality factor exceeding 2663 for visible frequencies. Our chiral metasurfaces promise a plethora of applications in chiral light sources and detectors, chiral sensing, valleytronics and asymmetric photocatalysis.

Dynamically encircling exceptional points (EPs) have unveiled intriguing chiral dynamics in photonics. However, the traditional approach based on an open manifold of Hamiltonian parameter space fails to explore trajectories that pass through an infinite boundary. Here, by mapping the full parameter space onto a closed manifold of the Riemann sphere, we introduce a framework to describe encircling-EP loops. We demonstrate that an encircling trajectory crossing the north vertex can realize near-unity asymmetric transmission. An efficient gain-free, broadband asymmetric polarization-locked device is realized by mapping the encircling path onto L-shaped silicon waveguides.

Topological quad-domain textures with interesting cross-shaped buffer domains (walls) have been recently observed in BiFeO3 (BFO) nanoislands, indicating a new platform for exploring topological defects and multilevel memories. Such domain textures have nevertheless only been limited in BFO nanoislands grown on LaAlO3 substrates with a large lattice mismatch of ∼-4.4%. Here, we report that such exotic domain textures could also form in BFO nanoislands directly grown on a conductive substrate with a much smaller lattice mismatch and the local transport characteristics of the BFO nanoislands are distinct from the previously reported ones. The angle-resolved piezoresponse force images verify that the domain textures consist of center-divergent quad-domains with upward polarizations and cross-shaped buffer domains with downward polarizations. Interestingly, textures with multiple crosses are also observed in nanoislands of larger sizes, besides the previously reported ones with a single cross. The nanoislands exhibit strong diodelike rectifying characteristics and the quad-domains show a higher average conductance than the cross-shaped buffer domains, indicating that there is a certain correlation between the local conductance of the nanoislands and the domain textures. This transport behavior is attributed to the effect of the depolarization field on the Schottky barriers at both the substrate/BFO interface and the tip/BFO junction. Our findings extend the current understanding of the exotic quad-domain textures of ferroelectric nanoislands and shed light on their potential applications for configurable electronic devices.

Refereed/Peer-reviewed A series of novel benzo[h]chromene compounds were designed, synthesized and evaluated for their biological activity as AcrB inhibitors. The compounds were assessed for their ability to potentiate the effect of antibiotics. Compounds with antibiotic-potentiating effects were then evaluated for inhibition of Nile Red efflux, and for off target effects including activity on the outer and inner bacterial membranes and toxicity. Six compounds were identified to reduce the MIC values of at least one of the tested antibiotics by at least 4-fold, and further reduced the MICs in the presence of a membrane permeabilizer. The identified compounds were also able to inhibit Nile Red efflux at concentrations between 50 μM and 200 μM. The compounds did not disrupt the bacterial outer membrane nor display toxicity in a nematode model (Caenorhabditis elegans). The 4-methoxyphenoxy)propoxy derivative compound G6 possessed the most potent antibacterial potentiation with erythromycin by 8-foldeven without the presence of a membrane permeabilizer. Furthermore, H6, G6, G10 and G11 completely abolished the Nile Red efflux at a concentration of 50 μM. The 3,4-dihydro-2H-benzo[h]chromen-5-yl)(morpholino)methanone core appears to be a promising chemical skeleton to be further studied in the discovery of more putative AcrB inhibitors.

Strong coupling between resonant states is usually achieved by modulating intrinsic parameters of optical systems, e.g., the refractive index of constituent materials or structural geometries. Externally introduced chiral enantiomers may couple resonances, but the extremely weak chirality of natural enantiomers largely prevents the system from reaching strong coupling regimes. Whether weak chirality could induce strong coupling between resonant states remains an open question. Here, we realize strong coupling between quasibound states in the continuum of a high-Q metasurface, assisted with externally introduced enantiomers of weak chirality. We establish a chirality-involved Hamiltonian to quantitatively describe the correlation between the coupling strength and the chirality of such systems, which provides an insightful recipe for enhancing the coupling of resonant states further in the presence of quite weak chirality. Consequently, high-sensitivity chiral sensing is demonstrated, in which the circular dichroism signal is enhanced 3 orders higher than the case without strong coupling. Our findings present a distinct strategy for manipulating optical coupling between resonances, revealing opportunities in chiral sensing, topological photonics, and quantum optics.

Diabetic nephropathy (DN) is known as a major microvascular complication in type 1 diabetes. The effect of insulin treatment alone on controlling blood glucose is unsatisfactory. N-acetylcysteine (NAC), a chemical agent with thiol group, is found to confer a protective effect in renal injury. However, whether NAC combined with insulin treatment can further enhance the therapeutic effect in DN remains unclear. Here, we firstly used large mammal beagle as DN model to explore the effect of NAC combined with insulin treatment on DN during 120 d. Our results showed that NAC further alleviated mitochondrial oxidative damage and ferroptosis by enhancing activity of mitochondria GSH and maintaining mitochondrial redox homeostasis in DN. Additionally, the upregulated acetylation level of SOD2 was further abrogated by NAC treatment. In MDCK cells, NAC reduced high glucose (HG)-caused ferroptosis via activating Gpx4 expression. Of note, inhibition of Gpx4 by FIN56 abolished the protective effects of NAC on HG-induced ferroptosis. More importantly, 3-TYP reversed the effect of NAC on the mitochondria ROS under HG treatment, as well as eliminated its following beneficial effects for ferroptosis against HG-stimulated cells. These results reveal that NAC attenuated ferroptosis in DN via maintaining mitochondrial redox homeostasis through activating SIRT3-SOD2-Gpx4 signaling pathway.

For reduction of vehicle weight and higher fatigue property, the hot-rolled dual-phase steel 700DP was developed to produce wheel disc with multistage stamping process. The wheel disc is one critical component of wheel system whose forming precision is extensively concerned. The critical area of the part characterizes nonlinear strain path during the multistage stamping process, which makes it difficult to accurately evaluate the formability through standard forming limit curve (FLC) method. The concept of equivalent plastic strain was reported to be strain path independent. Hence, in this paper, the formability of 700DP steel was studied through tensile test, Nakazima test, and two-step nonlinear formability test. It was certified that the modeling using the equivalent plastic strain–based FLC (ep-FLC) had better agreement with the two-step nonlinear test results. Then based on current die shape, the feasibility of 700DP steel for wheel disc with three-stage stamping process was studied by finite element method (FEM) with both traditional FLC and ep-FLC. Furthermore, the corresponding experiments were conducted for validation. The results show that the location and critical condition for the occurrence of fracture can be more exactly predicted by the ep-FLC compared with the traditional FLC. The process parameters such as the radius of die corner were then optimized by the modeling analysis. Finally, the wheel disc was successfully manufactured with high precision and sound mechanical property.

In various subdisciplines of optics and photonics, Mie theory has been serving as a fundamental language and playing indispensable roles widely. Conventional studies related to Mie scattering largely focus on local properties such as differential cross sections and angular polarization distributions. Though spatially integrated features of total cross sections in terms of both scattering and absorption are routine for investigations, they are intrinsically dependent on the specific morphologies of both the scattering bodies and the incident waves, consequently manifesting no sign of global invariance. Here, we propose a global Mie scattering theory to explore topological invariants for the characterization of scatterings by any obstacles of arbitrarily structured or polarized coherent light. It is revealed that, independent of distributions and interactions among the scattering bodies of arbitrary geometric and optical parameters, in the far field, inevitably, there are directions where the scatterings are either zero or circularly polarized. Furthermore, for each such singular direction, we can assign a half-integer index and the index sum of all those directions are bounded to be a global topological invariant of 2. The global Mie theory we propose, which is mathematically simple but conceptually penetrating, can render new perspectives for light scattering and topological photonics in both linear and nonlinear regimes and would potentially shed new light on the scattering of acoustic and matter waves of various forms.

We fabricate a ferroelectric field effect transistor (FeFET) based on a semiconducting vanadium dioxide (VO2) nanowire (NW), and we investigate its electron transport characteristics modulated by the ferroelectric effects. The transistor consists of a single VO2 NW as the channel and a ferroelectric Pb(Zr0.52Ti0.48)O3 (PZT) thin film as the dielectric gate. The conductance of the VO2 NW channel is found to be feasibly modulated by the ferroelectric gate with an 85% resistance change under the gate voltage of 18 V (at an applied field of about 0.75 MV cm-1). The electron transport property of the device can be controlled by the remnant polarization of the PZT layer due to the nonvolatile property of the ferroelectric gate, with an off-field change of channel resistance up to 50%. Moreover, multiple resistive states can be achieved by sweeping gate voltage across the device appropriately. These results demonstrate that ferroelectric gate modulation is an efficient tool to regulate the electron transport properties of the VO2 NW, and the VO2-NW-FeFET has potential applications in nonvolatile and low-power consumption devices.

Skyrmion transport fundamentally determines the speed, energy consumption, and functionality of skyrmion-based spintronic devices, attracting considerable attention. Recent experimental studies found there is a migration barrier for the thermal activated transport of a skyrmion, which is speculated to be induced by the pinning effects of crystalline defects. In this Letter, we propose an alternative source of migration barrier for skyrmion transport, i.e., a local lattice distortion field due to spin-lattice coupling, which can lead to the same Arrhenius diffusion behavior in defect-free skyrmion materials. By performing spin-lattice dynamics simulations, we study the microdynamic insight into the influence of local lattice distortion field, which refreshes the mechanistic understanding on skyrmion transport.

While the modification of skyrmion motion by edges and defects has been widely discussed, how the motion of skyrmions would be affected by a surface terrace remains unclear. In this work, micromagnetic simulations are performed to reveal the skyrmion transport behaviors in multilayers modified by a surface terrace. It is found that skyrmions can be partially nucleated or annihilated at the surface terrace, and the nucleation or annihilation process is related to the competition between the nucleation or annihilation barrier and the binding energy of skyrmions. Interestingly, such processes can effectively modulate the transport characteristics of the skyrmion. The skyrmion decelerates or is even blocked in the annihilation process, whereas it accelerates in the nucleation process. As a result, the skyrmion mobility can be very different between upward and downward motion, and the surface terrace can even be viewed as a surface diode for skyrmions. Meanwhile, a transverse shift of the skyrmion along the terrace occurs in the nucleation process and the shifting distance depends on the applied current. In this way, the skyrmion can be shifted to a specific trajectory by controlling the current. Based on these effects, we propose two prototypal skyrmionic devices, the skyrmion surface diode and skyrmion track selector, which are potentially useful in skyrmionics.

Given a constitutive relation of the bianisotropic medium, it is not trivial to study how light interacts with the photonic bianisotropic structure due to the limited available means of studying electromagnetic properties in bianisotropic media. In this paper, we study the electromagnetic properties of photonic bianisotropic structures using the finite element method. We prove that the vector wave equation with the presence of bianisotropic is self-adjoint under scalar inner product. we propose a balanced formulation of weak form in the practical implementation, which outperforms the standard formulation in finite element modeling. Furthermore, we benchmark our numerical results obtained from finite element simulation in three different scenarios. These are bianisotropy-dependent reflection and transmission of plane waves incident onto a bianisotropic slab, band structure of bianisotropic photonic crystals with valley-dependent phenomena, and the modal properties of bianisotropic ring resonators. The first two simulated results obtained from our modified weak form yield excellent agreements either with theoretical predictions or available data from the literature, and the modal properties in the last example, i.e., bianisotropic ring resonators as a polarization-dependent optical insulator, are also consistent with the theoretical analyses. [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material is available in the online version of this article at 10.1007/s12200-021-1213-5 and is accessible for authorized users.

Chiral optical effects are generally quantified along some specific incident directions of exciting waves (especially for extrinsic chiralities of achiral structures) or defined as direction-independent properties by averaging the responses among all structure orientations. Though of great significance for various applications, chirality extremization (maximized or minimized) with respect to incident directions or structure orientations have not been explored, especially in a systematic manner. In this study we examine the chiral responses of open photonic structures from perspectives of quasi-normal modes and polarization singularities of their far-field radiations. The nontrivial topology of the momentum sphere secures the existence of singularity directions along which mode radiations are either circularly or linearly polarized. When plane waves are incident along those directions, the reciprocity ensures ideal maximization and minimization of optical chiralities, for corresponding mode radiations of circular and linear polarizations respectively. For directions of general elliptical polarizations, we have unveiled the subtle equality of a Stokes parameter and the circular dichroism, showing that an intrinsically chiral structure can unexpectedly exhibit no chirality at all or even chiralities of opposite handedness for different incident directions. The framework we establish can be applied to not only finite scattering bodies but also infinite periodic structures, encompassing both intrinsic and extrinsic optical chiralities. We have effectively merged two vibrant disciplines of chiral and singular optics, which can potentially trigger more optical chirality-singularity related interdisciplinary studies., Several mislabellings in v1 are corrected, with Supplemental Material also included

The performance of organic polar tunnel junctions under external electrical/mechanical stimuli is crucial for their great promise in developing flexible and high-performance sensor and memristive devices. Here, we prepared a single P(VDF-TrFE) monolayer on an Au(111) atomic-level surface by using a Langmuir–Blodgett (LB) technique. The polarity stability and electronic transport behavior of the monolayer were investigated via piezoresponse force microscopy (PFM) and conductive atomic force microscopy (c-AFM) measurements. We observed a strong polarity asymmetry in the P(VDF-TrFE) monolayer tunnel junction. Electrical bias and mechanical force exerted by the tip both can switch the monolayer from the metastable state (“H–Au” state, down polarity) to the stable state (“F–Au” state, up polarity). Moreover, the conductance of the monolayer tunnel junction can be controlled not only by the electrical bias but also by the tip force. Interestingly, a decrease of conductance from the ON state to OFF state is caus...

Absract Considerable attention has been paid recently to coherent control of plasmon resonances in metadevices for potential applications in all-optical light-with-light signal modulation and image processing. Previous reports based on out-of-plane coherent control of plasmon resonances were established by modulating the position of a metadevice in standing waves. Here we show that destructive and constructive absorption can be realized in metallic nano-antennas through in-plane coherent control of plasmon resonances, which is determined by the distribution rule of electrical-field components of nano-antennas. We provide proof-of-principle demonstrations of plasmonic switching effects in a gold nanodisk monomer and dimer, and propose a plasmonic encoding strategy in a gold nanodisk chain. In-plane coherent control of plasmon resonances may open a new avenue toward promising applications in optical spectral enhancement, imaging, nanolasing, and optical communication in nanocircuits., Plasmonic devices: Better control with in-plane light Shining light along metal surfaces could provide unprecedented control of plasmons for optical devices, say researchers in China and Singapore. Localized surface plasmon resonances (LSPRs) are oscillations in conduction electrons coupled with light photons, which could act as information carriers for nano-sized optical sensors or even computers. Most attempts to control LSPRs use “out-of-plane” light incident at right angles to surfaces; however “in-plane” illumination—shining light at low angles across surfaces—also holds promise. Liyong Jiang and co-workers at Nanjing University of Science and Technology have demonstrated two new methods for in-plane illumination of LSPRs on gold nanodisks. They showed that they could not only switch the LSPRs into different states by adjusting the incident light, but also encode logical data onto chains of nanodisks, in ways that were not possible with out-of-plane illumination.

With the increasing incidence of antibiotic resistance, new antibacterial agents having novel mechanisms of action hence are in an urgent need to combat infectious diseases caused by multidrug-resistant (MDR) pathogens. Four novel series of substituted 9-arylalkyl-10-methylacridinium derivatives as FtsZ inhibitors were designed, synthesized and evaluated for their antibacterial activities against various Gram-positive and Gram-negative bacteria. The results demonstrated that they exhibited broad-spectrum activities with substantial efficacy against MRSA and VRE, which were superior or comparable to the berberine, sanguinarine, linezolid, ciprofloxacin and vancomycin. In particular, the most promising compound 15f showed rapid bactericidal properties, which avoid the emergence of drug resistance. However, 15f showed no inhibitory effect on Gram-negative bacteria but biofilm formation study gave possible answers. Further target identification and mechanistic studies revealed that 15f functioned as an effective FtsZ inhibitor to alter the dynamics of FtsZ self-polymerization, which resulted in termination of the cell division and caused cell death. Further cytotoxicity and animal studies demonstrated that 15f not only displayed efficacy in a murine model of bacteremia in vivo, but also no significant hemolysis to mammalian cells. Overall, this compound with novel skeleton could serve as an antibacterial lead of FtsZ inhibitor for further evaluation of drug-likeness.

Core concepts in singular optics, especially the polarization singularity, have rapidly penetrated the surging fields of topological and nonhermitian photonics. For open photonic structures with degeneracies in particular, the polarization singularity would inevitably encounter another sweeping concept of Berry phase. Several investigations have discussed, in an inexplicit way, the connections between both concepts, hinting at that nonzero topological charges for far-field polarizations on a loop is inextricably linked to its nontrivial Berry phase when degeneracies are enclosed. In this work, we reexamine the seminal photonic crystal slab that supports the fundamental two-level nonhermitian degeneracies. Regardless of the invariance of nontrivial Berry phase for different loops enclosing both exceptional points, we demonstrate that the associated polarization fields exhibit topologically inequivalent patterns that are characterized by variant topological charges, including even the trivial scenario of zero charge. It is further revealed that for both bands, the seemingly complex evolutions of polarizations are bounded by the global charge conservation, with extra points of circular polarizations playing indispensable roles. This indicates that tough not directly associated with any local charges, the invariant Berry phase is directly linked to the globally conserved charge, the physical principles underlying which have all been further clarified by a modified Berry-Dennis model. Our work can potentially trigger an avalanche of studies to explore subtle interplays between Berry phase and all sorts of optical singularities, shedding new light on subjects beyond photonics that are related to both Berry phase and singularities., The modified Berry-Dennis model in the previous version (arXiv:2006.06517v1) has been further refined, getting rid of the artificial field discontinuity

Topological quad-domain textures with interesting cross-shaped buffer domains (walls) have been recently observed in BiFeO