Dual Vortex Research Articles

Dual Frequency-Regulated Magnetic Vortex Nanorobots Empower Nattokinase for Focalized Microvascular Thrombolysis.

Magnetic nanorobots are emerging players in thrombolytic therapy due to their noninvasive remote actuation and drug loading capabilities. Although the nanorobots with a size under 100 nm are ideal to apply in microvascular systems, the propulsion performance of nanorobots is inevitably compromised due to the limited response to magnetic fields. Here, we demonstrate a nattokinase-loaded magnetic vortex nanorobot (NK-MNR) with an average size around 70 nm and high saturation magnetization for mechanical propelling and thermal responsive thrombolysis under a magnetic field with dual frequencies. The nanorobots are stable in suspension and undergo the magneto-steered assembly into chain-like NK-MNRs, which are regulated to generate magnetic forces to mechanically damage and penetrate the thrombus by the low-frequency rotating magnetic field. Synergistically, enhanced magnetic hyperthermia is triggered by an alternating magnetic field of high frequency, enabling heat-induced NK release and fibrinolysis. In this dual frequency-regulated magnetothrombolysis (fRMT) strategy, nanorobots collaborate under the dual magnetic energy conversion model to achieve the vasculature recanalization rate of 81.0% in thrombotic mice. Overall, the nanorobot with the special magnetic vortex property and multimodel controls is a promising nanoplatform for in vivo focalized microvascular thrombolysis.

Fermionized dual vortex theory for magnetized kagomé spin liquid

Abstract Inspired by the recent quantum oscillation measurement on the kagomé lattice antiferromagnet in finite magnetic fields, we raise the question about the physical contents of the emergent fermions and the gauge fields if the U(1) spin liquid is relevant for the finite-field kagomé lattice antiferromagnet. Clearly, the magnetic field is non-perturbative in this regime, and the finite-field state has no direct relation with the U(1) Dirac spin liquid proposal at zero field. We here consider the fermionized dual vortex liquid state as one possible candidate theory to understand the magnetized kagomé spin liquid. Within the dual vortex theory, the $S^z$ magnetization is the emergent U(1) gauge flux, and the fermionized dual vortex is the emergent fermion. The magnetic field polarizes the spin component that modulates the U(1) gauge flux for the fermionized vortices and generates the quantum oscillation. Within the mean-field theory, we discuss the gauge field correlation, the vortex-antivortex continuum and the vortex thermal Hall effect.

Modulation of optical force by adjusting the distance between three-layer photonic crystal slabs

Optical forces induced by polarization singularities from photonic crystal slabs (PCSs) have gained widely attention in recent years. To enhance the degree of freedom in controlling far-field optical forces, we propose and design a three-layer PCSs structure that simultaneously possesses multiple optical forces with reconfigurability. By modulating the interlayer spacing, the coupling strength between the slabs is regulated, resulting in a band transition from the nodal rings to the nodal ridge, which facilitates the generation of dual polarization vortices. These dual polarization vortices induce multiple phase singularities at their boundaries, leading to multiple optical force singularities, offering the possibility of capturing and dispersing nanoparticles. Interestingly, tuning the spacing among the slabs can transform the converging force into the diverging force at the center, therefore achieving particle screening. This work not only expands the application of nodal ridges to optical force in photonic structures but also provides a feasible approach for the generation of double-ring vortex beam in the nano-optics field.

Dual coaxial electric field components in tightly focused circularly polarized Pearcey beams

The optical vortex, with its capacity to carry orbital angular momentum per photon, has garnered significant attention among researchers. Our study showcases the emergence of dual coaxial longitudinal electric field vortices during the non-paraxial propagation of tightly focused circularly polarized Pearcey beams. Our research indicates that combining the self-focusing characteristics of Pearcey beams with the tight focusing effect results in the formation of four focal points. We have achieved controllable adjustment of four distinct focal points. This study also encompasses a detailed numerical analysis of the application in optical trapping, and we investigate and elucidate the trapping strength and corresponding potential energies.

Generation of dual vortices with controlled topological charges based on spin-decoupled moiré metalens.

By their powerful talent in manipulating optical parameters, metasurfaces demonstrate great ability in the generation of the vortex beams. Until now, vortex beam generators constructed by metasurfaces mostly lack tunability, which reduces the scope of their applications. Here, spin-decoupled moiré metalenses composed of two cascaded all-dielectric metasurfaces are designed. Utilizing mathematical derivation and numerical simulation, dual vortices with variable topological charge can be generated under the incidence of orthogonal circularly polarized light by tuning the mutual rotation between the two cascaded metasurfaces. Meanwhile, vector vortex beams can be produced by superposition of dual focused vortices under the linearly polarized light illumination and whose vector polarized states can also be manipulated by mutual rotation. This work provides a flexible design strategy for continuous manipulation of singular beams, which have potential applications in optical communication, microparticle manipulation, and super-resolution imaging.

Investigating the influence of stepped roofs on wind dynamics using large eddy simulation

This study investigates airflow and turbulence within varying roof configurations in urban boundary layers by using the parallelized large-eddy simulation model (PALM). Key findings reveal stark contrasts in airflow between stepped and flat roof arrangements, with the former presenting dual counter-rotating vortices and enhanced vertical motion in one street, while the latter exhibited a primary vortex and several secondary vortices. Additionally, normalized turbulence kinetic energy (TKE) was markedly lower in flat roof configurations, with stepped roofs fostering more significant turbulence and small-scale turbulent motion. This variability intensified with decreasing step height and quantity. Vertical profiles further disclosed considerable velocity disturbances and larger Reynolds numbers in one street of stepped roofs, affirming the roof’s influence on turbulence generation and transport. Dispersive stress also displayed differing characteristics in various canyons. Turbulent momentum transport through eddies significantly differs between the windward and leeward streets of flat and stepped roofs. Further exploration into density stratification effects and scalar transport in stepped roofs would enhance practical implications.

Full-cycle study on developing a novel structured micromixer and evaluating the nanoparticle products as mRNA delivery carriers

Achieving precise control of nanoparticle size while maintaining consistency and high uniformity is of paramount importance for improving the efficacy of nanoparticle-based therapies and minimizing potential side effects. Although microfluidic technologies are widely used for reliable nanoparticle synthesis, they face challenges in meeting critical homogeneity requirements, mainly due to imperfect mixing efficiency. Furthermore, channel clogging during continuous operation presents a significant obstacle in terms of quality control, as it progressively impedes the mixing behavior necessary for consistent nanoparticle production for therapeutic delivery and complicates the scaling-up process. This study entailed the development of a 3D-printed novel micromixer embedded with hemispherical baffle microstructures, a dual vortex mixer (DVM), which integrates Dean vortices to generate two symmetrical counter-rotating intensified secondary flows. The DVM with a relatively large mixer volume showed rapid mixing characteristics even at a flow rate of several mL min−1 and produced highly uniform lipids, liposomes, and polymer nanoparticles in a size range (50–130 nm) and polydispersity index (PDI) values below 0.15. For the evaluation of products, SARS-CoV-2 Spike mRNA-loaded lipid nanoparticles were examined to verify protein expression in vitro and in vivo using firefly luciferase (FLuc) mRNA. This showed that the performance of the system is comparable to that of a commercial toroidal mixer. Moreover, the vigorous in-situ dispersion of nanoparticles by harnessing the power of vortex physically minimizes the occurrence of aggregation, ensuring consistent production performance without internal clogging of a half-day operation and facilitating quality control of the nanoparticles at desired scales.

Dual perfect vectorial vortex beam generation with a single spin-multiplexed metasurface

Perfect optical vortex beams (POVBs) carrying orbital angular momentum (OAM) possess annular intensity profiles that are independent of the topological charge. Unlike POVBs, perfect vectorial vortex beams (PVVBs) not only carry orbital angular momentum but also exhibit spin angular momentum (SAM). By incorporating a Dammann vortex grating (DVG) on an all-dielectric metasurface, we demonstrate an approach to create a pair of PVVBs on a hybrid-order Poincaré sphere. Benefiting flexible phase modulation, by engineering the DVG and changing the input-beam state we are able to freely tailor the topological OAM and polarization eigenstates of the output PVVBs. This work demonstrates a versatile flat-optics platform for high-quality PVVB generation and may pave the way for applications in optical communication and quantum information processing.

Tunable multifunctional terahertz metasurface based on an indium antimonide medium

Active adjustable terahertz multifunctional devices are crucial for the application of terahertz technology. In this paper, we propose a composite metasurface structure based on an indium antimonide metal octagonal pattern, which achieves different functional switching by controlling the phase state of indium antimonide material under different ambient temperatures. When indium antimonide exhibits in the dielectric state, by stacking and encoding the unit cell, the designed metasurface has the functions of two-beam splitting beam superposition, vortex beam and quarter beam superposition, and dual vortex beam superposition for circularly polarized and linearly polarized wave incidence. When indium antimonide appears in the metallic state, the encoding metasurface alters the modulation function of incident circularly polarized and linearly polarized terahertz waves. This terahertz metasurface provides a new approach for the design of multifunctional devices that can flexibly regulate terahertz wave metasurfaces.

Experimental realization of a transmissive microwave metasurface for dual vector vortex beams generation

This work presents a theoretical design and experimental demonstration of a transmissive microwave metasurface for generating dual-vector vortex beams (VVBs). The proposed metasurface consists of an array of pixelated dartboard discretization meta-atoms. By rotating the meta-atoms from 0° to 180°, a Pancharatnam-Barry (P-B) phase covering the full 360° range is achieved, with a transmittance exceeding 90% over the frequency range from 9.7 to 10.2 GHz. The measured results demonstrate that when a linearly polarized microwave normally impinges on the metasurface, the transmitted beams correspond to the dual VVBs with different directions. A good agreement among Poincaré sphere theory, full-wave simulation, and experimental measurement is observed. This proposed transmissive microwave metasurface for VVBs may offer promising applications in communications and radar detection.

Electric properties of the twelve-fold vortex structure in hexagonal manganites

Hexagonal manganites, as a functional ferroelectric (FE) material, receive considerable attention due to their improper ferroelectricity and topological vortex structures. This family exhibits three low-symmetry states accompanied by distinct vortex domain structures. In addition to the FE P63 cm and anti-FE (AFE) P-3c1 states accompanied by dual six-fold vortex structures, there is another FE P3c1 state accompanied by a twelve-fold vortex structure. The responses of FE materials to external stimuli, such as external electric fields, are the core ingredients in the physics of FEs and are significant for technological applications. Under external electric fields, the responses of FE materials are determined by special FE domain structures. The electric properties of the FE P63 cm and AFE P-3c1 states are very different. However, the electric properties of the FE P3c1 state, which only stabilizes in Ga-substituted In(Mn, Ga)O3, are unclear. The present work studies the electric properties of the FE P3c1 state. The electric-field-driven transition of the FE P3c1 state is found to follow two sequences, i.e. (1) twelve-fold P3c1 → nine-fold P3c1 + P63 cm → three-fold P63 cm, and (2) twelve-fold P3c1 → six-fold P3c1 → three-fold P63 cm. The variation of average polarization with E for the FE P3c1 state with the second transition sequence manifests as an unusual triple-hysteresis loop, different from the usual single-hysteresis loop of FE materials. The results are related to the coexistence of the FE and non-FE domain walls in the FE P3c1 state. Furthermore, it is found that the FE P3c1 state at substitution concentration 0.39 exhibits the highest dielectric response. The results advance our understanding of topological vortex structures in hexagonal manganites.

Analysis of Tangential Leakage Flow Characteristics in a Variable Diameter Dual Circular Arc Vortex Compressor

(1) To address issues such as a low compression ratio and severe leakage in uniform wall thickness vortex compressors, this paper adopts a new scroll compressor model with a variable diameter double arc combined profile, which has a larger pressure ratio and smaller leakage than the scroll compressor with equal wall thickness that can bring new ideas and methods to the research in the field of scroll compressors. (2) This paper determines the theoretical equation of the variable diameter dual circular arc vortex profile and the combined profile, and infers mathematical models for the leakage line length, working chamber volume, and gas leakage per unit rotation angle of the vortex compressor, followed by simulation. (3) The results show that compared to the uniform wall thickness involute profile, the variable diameter dual circular arc combined profile model reduces the leakage line length by 25%, increases the average total pressure at the working chamber outlet by 2.38%, and decreases the leakage amount by 3.2%, consistent with theoretical analysis. (4) The tangential leakage caused by the radial gap in the variable diameter dual circular arc combined profile model has a significant impact on the uneven distribution of temperature and velocity fields in the working chamber of the vortex compressor, but a smaller impact on the pressure field.

Mathematical modelling of couple stress fluid flow around a semi‐permeable sphere enclosing a solid core

AbstractThe focus of this article is to study theoretically the steady‐axisymmetric creeping flow dynamics of a couple stress fluid external to a semi‐permeable sphere containing a solid core. This problem is motivated by emulsion hydrodynamics in chemical engineering where rheological behaviour often arises in addition to porous media effects. The non‐Newtonian Stokes’ couple stress fluid model features couple stresses and body couples that are absent in the classical Navier–Stokes viscous model. It provides a robust framework for simulating emulsions, complex suspensions and other liquids which possess microstructure. The physical regime is delineated into two zones – the interior of the semi‐permeable zone (region II) which engulfs the solid core and the external couple stress fluid zone (region I). The model is formulated using a spherical polar coordinate system in terms of the stream function ψ. The Brinkman‐extended Darcy model is deployed for the porous medium hydrodynamics and isotropic permeability is considered. Analytical expressions are derived for dimensionless pressure, tangential stress and the couple stress components using the method of separation of variables and Gegenbauer functions of the first kind. The integration constants are evaluated with appropriate boundary conditions on the inner and outer boundary of the semi‐permeable zone with the aid of Mathematica symbolic software. Solutions for the drag force exerted by the couple stress fluid on the semi‐permeable sphere and volumetric flow rate are also derived with corresponding expressions for the drag coefficient and non‐dimensional volumetric flow rate. The influence of permeability (k), separation parameter (l), couple stress viscosity coefficient (η), couple stress inverse length dependent parameter (λ = √(μ/η)) and couple stress viscosity ratio (τ = η/η/) on all key variables is studied graphically. Additionally, streamline contours are computed for a range of parameters including inverse permeability parameter (α = 1/k). The computations show that increasing couple stress inverse length dependent parameter (λ) greatly reduces the dimensionless volumetric flow rate in particular at high values of separation parameter (l). Flow rate is, however, markedly enhanced with permeability (k) and also couple stress viscosity parameter (η). In the presence of the solid core, a much greater drag coefficient is observed at all values of couple stress inverse length dependent parameter (λ) relative to the case without a solid core. A significant distortion in streamlines is computed with increasing separation parameter (l) with a dual vortex structure emanating. With greater couple stress viscosity parameter (τ), no tangible modification is observed in the streamline contours. The present work generalizes the earlier study of Krishnan and Shukla to consider a semi‐permeable (porous medium) outer sphere and furthermore presents detailed streamline visualizations of the creeping flow for a range of emerging parameters of relevance to non‐Newtonian chemical engineering processes including emulsion droplet dynamics in porous materials.

Spatiotemporal coupling induced controllable orientation of photonic orbital angular momentum at subwavelength scale.

Recently, the emergence of transverse orbital angular momentum (OAM) as a novel characteristic of light has captured substantial attention, and the significance of adjustable OAM orientation has been underscored due to its pivotal role in the interaction between light and matter. In this work, we introduce a novel approach to manipulate the orientation of photonic OAM at subwavelength scales, leveraging spatiotemporal coupling. By tightly focusing a wavepacket containing dual spatiotemporal vortices and a spatial vortex through a high numerical aperture lens, the emergence of intricate coupling phenomena leads to entangled and intricately twisted vortex tunnels. As a consequence, the orientation of spatial OAM deviates from the conventional light axis. Through theoretical scrutiny, we unveil that the orientation of photonic OAM within the focal field is contingent upon the signs of the topological charges in both spatiotemporal and spatial domains. Additionally, the absolute values of these charges govern the precise orientation of OAM within their respective quadrants. Moreover, augmenting the pulse width of the incident light engenders a more pronounced deflection angle of photonic OAM. By astutely manipulating these physical parameters, unparalleled control over the spatial orientation of OAM becomes achievable. The augmented optical degrees of freedom introduced by this study hold considerable potential across diverse domains, including optical tweezers, spin-orbit angular momentum coupling, and quantum communication.

Bosonic flux ladder considering the next nearest neighbor kinetic tunneling

We investigate interacting bosons in a two-leg lattice, which is subject to an uniform artificial magnetic field. Its Hamiltonian takes into account the next nearest neighbor kinetic tunneling term, along the principal diagonal direction. With the help of an inhomogeneous dynamical Gutzwiller mean-field theory, we figure out four novel quantum phases of the system site by site, three of which are the dual vortex lattice, the triplet vortex lattice, and the composite vortex lattice. They particularly present parallelogram vortical particle currents, inside those conventional rectangular vortical currents, due to the import of next nearest neighbor kinetic tunneling. Under certain parameters, we further identify the crossed circulation lattice featuring alternating sequences on local currents and occupancies, whose minimal periods are determined by the value of flux quanta.

Complete polarization modulates arbitrary dual optical vortices in free space

Modulation of the position and shape of the double optical vortex with opposite phases is perplexing scientists due to the complex polarization of Pancharatnam–Berry. In this paper, we used an optical pen and cross-phase to solve these problems. Importantly, the topological charges of the dual optical vortex produced by this method are independent of each other, the shape of which is polygonal and the position of which can be predesigned in free space. The dual optical vortex can keep its amplitude, size, and shape in a certain propagation process. These characteristics help it to have a good application prospect in the fields of micromanipulation and optical tweezers, as well as other multidimensional operations.

Numerical Analysis of Temperature Separation and Exergy Analysis of a Dual-Inlet Section Convergent Vortex Tube

Abstract The present study deals with the optimization of a counter flow vortex tube with a straight single intake section, straight dual intake section, and convergent dual intake section vortex tube model for different physical and flow parameters. The effect of variation of convergent angles (θ), intake pressures, and a number of inlet sections on the flow separation has been analyzed in the present study. ANSYS FLUENT software has been used to simulate flow considering air as a working fluid. Moreover, some physical and flow parameters such as intake pressure, cold temperature gradient (ΔTc), pressure loss ratio, cold mass fraction, and hot temperature gradient (ΔTh) have been studied to optimize the vortex tube. The coefficient of performance has been compared for various convergent angles from 1 deg to 5 deg. The result has been validated by the experimental and numerical studies performed previously. Moreover, the exergy analysis has also been conducted for the convergent dual intake vortex tube for various convergent angles, cold mass fraction, and intake pressure. The study concludes that the convergent vortex tube having a dual inlet section, 5-deg angle shows the optimized result for all the mass fraction and intake pressure, compared to a straight single intake section and straight dual intake vortex tube.

Red, orange, and dual wavelength vortex emission from Pr:WPFGF fiber laser using a microscope slide output coupler.

Visible vortex beams have a large array of applications; however, the sources are often large or complex. Here, we present a compact vortex source with red, orange, and dual wavelength emission. This Pr:Waterproof Fluoro-Aluminate Glass fiber laser uses a standard microscope slide as an interferometric output coupler, yielding high quality first order vortex modes in a compact setup. We further demonstrate the broad (∼5 nm) emission bands in the orange (610 nm), red (637 nm) and near-infrared regions (698 nm), with the potential for green (530 nm) and cyan (485 nm) emission. This is a low-cost, compact and accessible device giving high quality modes for visible vortex applications.

Effects of streamwise aspect ratio on the spatio-temporal characteristics of flow around rectangular cylinders

Turbulent flows over rectangular cylinders with streamwise aspect ratios (AR) of 1, 2 and 4 were experimentally studied using time-resolved particle image velocimetry at a Reynolds number based on free-stream velocity and cylinder height of 16200. These aspect ratios represent cylinders for which the mean separated shear layers from the leading edges are shed directly into the wake region (AR1), reattach over the cylinder (AR4), and an intermediate case (AR2). The effects of aspect ratio on the transport phenomena, turbulence production and its budget are investigated. The spatio-temporal characteristics and the interactions between the small-scale Kelvin-Helmholtz (KH) vortices and the energetic large-scale von-Kármán (VK) vortices are examined using frequency spectra, while the dynamics of the coherent structures are elucidated using proper orthogonal decomposition (POD). The mean flow topology reveals a massive recirculation bubble in the wake of the AR2 cylinder, compared to AR1 and AR4. While a single dominant vortex shedding frequency is observed for AR1 and AR4, a dual vortex shedding instability is manifested for the AR2 cylinder, which is intimately connected with the intermittent reattachment and detachment of flow over the AR2 cylinder. The interactions between the KH and VK vortices are shown to vary non-linearly with aspect ratio, as the flow transitions from the fully detached case (AR1) to fully reattached case (AR4). The differences in the vortex shedding process are revealed in the dynamics of the first POD mode pair. For AR1 and AR4, the fundamental shedding frequency is dominant and the first POD mode pair contain similar energy content, suggesting regular vortex shedding patterns. For AR2, dual shedding frequencies are observed with significant cycle-to-cycle variation, suggesting irregular vortex shedding patterns.

Dual vortex retarder Mueller matrix ellipsometry

We propose a dual vortex retarder Mueller matrix ellipsometry (DVRMME) that can extract 16 Mueller matrix elements by analyzing a single intensity image. Two customized vortex quarter wave retarders (VQWRs) with different orders are employed to realize the spatial modulation in the polarization state generation (PSG) and polarization state analyzing (PSA) arms. Due to the spatial polarization modulation by VQWRs, a pattern with regularly varying intensity along the azimuth direction is formed, and the sample's Mueller matrix can be obtained by processing the modulated intensity image. The ellipsometry's working principle has been elaborated by the Stokes-Mueller formalism, and its main error sources are presented and analyzed, and then a modulation vector calibration method is proposed to reduce the measurement error. To verify the validity of the scheme, the DVRMME has been constructed and demonstrated in experiment. The Mueller matrices of air, polarizer and retarder were measured, and their RMS errors of 16 Mueller matrix elements were respectively less than 0.0110, 0.0094 and 0.0180, and their maximum absolute errors were respectively less than 0.0196, 0.0230 and 0.0352.