Particle Trapping Research Articles

Precise mass measurements of A = 133 isobars with the Canadian Penning Trap: Resolving the [formula omitted] anomaly at 133Te

We report precision mass measurements of 133Sb, 133g,mTe, and 133g,mI, produced at CARIBU at Argonne National Laboratory's ATLAS facility and measured using the Canadian Penning Trap mass spectrometer. These masses clarify an anomaly in the 133Te β-decay. The masses reported in the 2020 Atomic Mass Evaluation (M. Wang et al., 2021) produce Qβ−(133Te)=2920(6) keV; however, the highest-lying 133I level populated in this decay is observed at Ei=2935.83(15) keV, resulting in an anomalous Qβ−i=−16(6) keV. Our new measurements give Qβ−(Te133)=2934.8(11) keV, a factor of five more precise, yielding Qβi=−1.0(12) keV, a 3σ shift from the previous results. This resolves this anomaly, but indicates further anomalies in our understanding of the structure of this isotope.

Intrinsic angular momentum, spin and helicity of higher-order Poincaré modes

Abstract The availability of coherent sources of higher order Poincaré optical beams have opened up new opportunities for applications such as in the optical trapping of atoms and small particles, the manipulation of chirally-sensitive systems and in improved encoding schemes for broad-bandwidth communications. Here we determine the intrinsic properties of integer order m ⩾ 0 Poincaré Laguerre–Gaussian (LG) modes which have so far neither been evaluated, nor their significance highlighted. The theoretical framework we adopt here is both novel and essential because it emphasises the crucial role played by the normally ignored axial components of the twisted light fields of these modes. We show that the inclusion of the axial field components enables the intrinsic properties of the Poincaré modes, notably their angular momentum, both spin and orbital as well as their helicity and chirality, to be determined. We predict significant enhancements of the intrinsic properties of these modes when compared with those due to the zero order LG modes. In particular, we show that higher order LG Poincaré modes exhibit super-chirality and, significantly so, even in the case of the first order m = 1.

Mineralogical characterization of magnesium-based nanoparticles recovered from a swirl-stabilized magnesium flame by analytical and scanning/transmission electron microscopy

Abstract. The current climate emergency and the related energy transition require the development of technology producing zero-carbon energy. One viable option entails the utilization of recyclable metal fuels. The primary energy stored by the reduction in metal oxides can be transported and later released by metal combustion. Mg is among the most promising metal as a regenerable energetic vector, having an energy density of 25 MJ kg−1. The exploitation of the Mg oxidation and reduction loop has recently been demonstrated, and the loop combustion products are made of metal oxides. The mineralogical characterization of the MgO crystals generated by the Mg combustion is of utter importance for the optimization of the particle trapping capacity in the combustion system during the closed oxidation and reduction loop. In this paper we characterize MgO particles generated in a swirl-stabilized Mg flame by using powder X-ray diffraction, transmission electron microscopy and selected area electron diffraction, and atomic-resolution microscopy combined with energy-dispersive X-ray spectroscopy and dual-electron energy-loss spectroscopy. The MgO combustion products were chemically homogeneous at this level of investigation. Three representative morphologies (cubic, truncated octahedron, and spherical) and two isostructural phases were identified in the MgO combustion product. These findings may contribute to the optimization of system development, particularly in terms of the collection efficiency of the combustion end product.

Generation of circular symmetric Airy vortex beams based on spin-multiplexed metasurface

Given that circular symmetric Airy vortex beam (CSAVB) was found to possess a stable central cavity and an opposing transport process to circular Airy vortex beam, it has been recognized as a potentially powerful tool for particle trapping and optical communication. In order to facilitate broader application scenarios, this paper presents a novel approach to the generation of multiple CASVBs based on a single metasurface. In the proposed method, three independent CSAVBs carrying different new kinds of power-exponent-phase vortices (NPEPVs) can be obtained under two orthogonal circularly polarized or an arbitrary linear polarized incident, respectively. Each of these vortex structures is characterized by a distinct orbital angular momentum, which is jointly determined by two parameters of the NPEPVs. This indicates that the CSAVB and the device have greater freedom than the canonical optical vortex beams and the previous vortex beam generators in controlling the optical vortex. These results have the potential to advance the development of vortex beams and enhance their applications in micromanipulation, optical communication and imaging.

Rapid Downwelling of Tracer Particles Across the Boundary Layer and Into the Pycnocline at Submesoscale Ocean Fronts

AbstractA neutrally buoyant float deployed in an atmospherically driven turbulent ocean boundary layer on the dense side of a submesoscale front was repeatedly carried across the boundary layer by the turbulence and then trapped beneath the slumping front. Lagrangian particles in a large‐eddy simulation of a similar baroclinically unstable front forced by surface cooling move along convergent surface filaments toward filament junctions. They are also caught by convective plumes that downwell them at speeds similar to those of the float. Subsequently, some are trapped in the pycnocline by frontal slumping due to ageostrophic secondary frontal circulations. In both observations and simulations, boundary layer turbulence and frontal circulations work together to trap and subduct particles from the mixed layer. The small‐scale boundary layer motions move them vertically within the boundary layer and larger, submesoscale frontal circulations move them laterally out of the boundary layer and under the slumping fronts.

Dynamic behavior and mechanistic analysis in filtration of dilute particulate suspensions through nanofibrous membrane

Nanofibrous membranes have garnered significant interest in membrane filtration due to their high porosity, small pore sizes, and complex interconnected pore structures. Although many studies focus on size exclusion in surface filtration, the filtration behavior and mechanisms for particles smaller than the pore size have been relatively underexplored. In this study, membrane filtration using nanofibrous membranes was employed to elucidate the filtration behavior and mechanisms for polystyrene latex suspensions with particles smaller than the pore size. The results indicated that reducing fiber diameter decreases the pore size and enhances particle rejection, with particle retention occurring within the intricate three-dimensional nanofiber pore network. In contrast, the effect of the membrane’s basis weight was less significant compared to fiber diameter. This observation can be attributed to the concept of effective thickness; once this thickness is exceeded, particles are prevented from penetrating deeper into the membrane. The filtration model was analyzed using Hermans-Bredée blockage filtration theory and cake filtration theory, considering the mass of trapped particles within the membranes. The model characterizes the filtration process as initially following standard blocking, progressing to cake filtration once a sufficient number of pores become clogged.

Resolved-sideband cooling of a single Be+9 ion in a cryogenic multi-Penning-trap for discrete symmetry tests with (anti-)protons

Manipulating the motion of individual trapped ions at the single quantum level has become standard practice in radio-frequency ion traps, enabling sweeping advances in quantum information processing and precision metrology. The key step for motional-state engineering is ground-state cooling. Full motional control also bears great potential to explore another regime of sensitivities for fundamental physics tests in Penning traps. Here we demonstrate the key enabling step by implementing resolved-sideband cooling on the axial mode of a single Be+9 ion in a 5 Tesla cryogenic Penning trap. The system has been developed for the implementation of high-precision antimatter experiments to test the fundamental symmetries of the standard model with the highest accuracy in the baryonic sector. We measure an axial phonon number of n¯z=0.10(4) after cooling and demonstrate that the axial heating rate in our system is compatible with the implementation of quantum logic spectroscopy of (anti-)protons. Published by the American Physical Society 2024

Electrokinetic particle trapping in microfluidic wells using conductive nanofiber mats.

The frequency dependence of electrokinetic particle trapping using large-area (>mm2) conductive carbon nanofiber (CNF) mat electrodes is investigated. The fibers provide nanoscale geometric features for the generation of high electric field gradients, which is necessary for particle trapping via dielectrophoresis (DEP). A device was fabricated with an array of microfluidic wells for repeated experiments; each well included a CNF mat electrode opposing an aluminum electrode. Fluorescent microspheres (1µm) were trapped at various electric field frequencies between 30kHz and 1MHz. Digital images of each well were analyzed to quantify particle trapping. DEP trapping by the CNF mats was greater at all tested frequencies than that of the control of no applied field, and the greatest trapping was observed at a frequency of 600kHz, where electrothermal flow is more significantly weakened than DEP. Theoretical analysis and measured impedance spectra indicate that this result was due to a combination of the frequency dependence of DEP and capacitive behavior of the well-based device.

Arbitrage equilibria in active matter systems

The motility-induced phase separation (MIPS) phenomenon in active matter has been of great interest for the past decade or so. A central conceptual puzzle is that this behavior, which is generally characterized as a nonequilibrium phenomenon, can yet be explained using simple equilibrium models of thermodynamics. Here, we address this problem using a new theory, statistical teleodynamics, which is a conceptual synthesis of game theory and statistical mechanics. In this framework, active agents compete in their pursuit of maximum effective utility, and this self-organizing dynamics results in an arbitrage equilibrium in which all agents have the same effective utility. We show that MIPS is an example of arbitrage equilibrium and that it is mathematically equivalent to other phase-separation phenomena in entirely different domains, such as sociology and economics. As examples, we present the behavior of Janus particles in a potential trap and the effect of chemotaxis on MIPS.

Soliton interaction in a two-temperature electron plasma with trapping and superthermality effects

Head-on collision of the two small-amplitude electron-acoustic (EA) solitons is studied in an unmagnetized collisionless plasma in the presence of superthermal (hot) trapped electrons. For this purpose, using a well-known extended Poincare–Lighthill–Kuo (PLK) method, a pair of the trapped Korteweg–de Vries (tKdV) equations is derived to investigate the soliton trajectories and phase shifts. The latter are found dependent on amplitudes of the interacting solitons, effectively altering with hot-electron superthermality and plasma parameters. Typical parameters for the electron diffusion region (EDR) and day-side auroral zone have been selected to examine the impact of hot-electron superthermality, trapping parameter, hot-to-cold electron number density ratio, and cold-to-hot electron temperature ratio on the profiles of potential excitations and phase shifts of interacting solitons. It is found that phase speed of the EA waves becomes altered by varying the κ–parameter, strongly modifying the nonlinearity and dispersive coefficients in a superthermal trapped plasma. However, particle trapping phenomenon does not affect the linear phase speed but introduces a fractional nonlinearity in the tKdV equations of two interacting solitons. The impact of the adiabatic and isothermal pressures is also highlighted to show new modifications in the propagation characteristics of two interacting solitons.

Ripple-induced neoclassical toroidal viscous torque in Augmented-First Plasma operation phase in ITER

Abstract A systematic calculation is performed on the ripple-induced neoclassical toroidal viscous (NTV) torque for new ITER scenarios designed for the Augmented-First Plasma (A-FP) operation phase with the full tungsten wall, where the plasma-wall gap is varied in view of mitigating the impact of tungsten wall-plasma interactions. The torque calculation includes drift kinetic response of the plasma thermal and energetic particles to the n = 18 (n is the toroidal harmonic number) ripple field. For the plasma scenario with ~45 cm plasma-wall gap at the outboard mid-plane and considering the corrected ripple level of 0.17% by the ferritic steel inserts, the computed net NTV torque acting on the plasma column is in the sub-Nm level. However, with decreasing the plasma-wall gap, the computed net NTV torque can reach a level comparable to that produced by the neutral-beam momentum injection in ITER. Ripple correction by ferritic inserts reduces the net torque by a factor of 3.3 for all the three A-FP scenarios considered. The n ω d = l ω b (with ω d and ω b being the toroidal precession and bounce frequencies of trapped particles, respectively, and l an integer number) type of resonance-enhancement of the NTV torque, due to thermal particles, is found to be weak in ITER despite high-n of 18. The same also holds for the ITER 10 MA steady state scenario from the D-T operation phase, where the aforementioned resonance associated with fusion-born alphas is also included. The ripple-induced NTV torque is well below that produced by the resonant magnetic perturbation applied for controlling the type-I edge-localized mode in ITER.

Application of Resonant Plasmonic Bowtie Nanoantennas for Optically‐Assisted Diffusiophoretic Trapping of Extracellular Vesicles and Nanoparticles

AbstractPlasmonic antennas leveraging localized surface plasmon resonances (LSPR) hold a significant premise for efficiently trapping nanoscale particles at low power levels. However, their effectiveness is hindered by photothermal effects that arise with metallic nanoparticles, leading to decreased stability of trapped particles. To address this limitation, a hybrid approach that combines depletion attraction and photothermal effects inherent in plasmonic structures is proposed, capitalizing on thermally induced concentration gradients. Through the thermophoretic depletion of polyethylene glycol (PEG) molecules around plasmonic hotspots, sharp concentration gradients are created, enabling precise localization of nanoscopic particles through a synergistic effect with diffusiophoretic forces. Our experiments successfully demonstrate the ability to trap and dynamically manipulate small extracellular vesicles and 100 nm polystyrene beads, showcasing the platform's potential for assembly at the nanoscale. Remarkably, this method maintains stable trapping performance even at a laser power of . The demonstration of stable trapping of small extracellular vesicles showcases the compatibility of this platform with bio species. This study introduces a promising avenue for the precise and efficient manipulation of nanoscale particles, with wide‐ranging implications in nanotechnology, biophysics, and nanomedicine. This research opens new opportunities for advancing nanoscale particle studies and applications, ushering in a new era of nanoscale manipulation techniques.

Development and In vivo Evaluation of Nanogel Drug Delivery System for Promoting Wound Healing in Diabetic Induced Rats

Recently, researchers have looked at the use of nanotechnology as a drug-delivery system for topical and transdermal applications. The transport of medications and active ingredients to the skin via formulations, including nanoparticles, is a subject of substantial contemporary interest. The present work is proposed to prepare the atorvastatin nanogels to promote wound healing in a diabetic animalmodel.Atorvastatin nanogels were prepared by precipitation polymerization technique using hydroxy propyl methacrylate as polymer. The drug and polymer were selected in ratios of 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7 and 1:8. Additionally, the produced nanogel was evaluated in vivo and examined for its particle size, trapping effectiveness, and drug release in vitro. The particle size of the prepared various formulations (F1-F8) showed a size range of 68 to 80nm, and entrapment efficiency was seen to be in the range of 58.36-86.75%. The cumulative percentage of drug release was reported to be 61.96 to 73.76 percent over a period of 12hours during the in vitro drug release investigation, which was conducted using phosphate buffer at pH 7.4.The drug release followeda non-fiction mechanism of release kinetics. On the other hand, in vivo comparative study showed a complete wound healing effect for nanogels on the 11th day, whereas for conventional gel on the 15th day.This study indicates that nanogels formulation heals the diabetic wound completely at a faster rate, and also the drug atorvastatin also can be used for diabetic wound healing.

Optical manipulations without light forces: deep superlattice for trapping and rotation of impurity particles in a buffer gas

We propose a scheme to obtain a deep optical superlattice (OSL) for resonant impurity particles in a buffer gas. In contrast to the well-known traditional methods of forming optical lattices (supelattices) that are based on the gradient force of radiation pressure, the presented scheme is based on the effect of a light induced drift (LID) in interfering light waves. The principle of its operation is based on the conception of so-called rectified forces induced by interfering bichromatic optical fields, which was developed earlier in the theory of resonant radiation-pressure forces. In the scheme under consideration, a deep OSL (with a period much larger than the optical wavelength) is formed due to the action of the effective rectified force on atomic particles which is proportional to the difference between the frequencies of transport collisions of excited and unexcited particles with buffer gas atoms.

Formation of subwavelength tunable flat-top focus with double foci characteristic by tightly focused cylindrical vector beams

We report a numerical investigation on the generation of a subwavelength flat-top focus by tuning the polarization angle of the incident beam under tight focusing conditions. Our approach uses a binary phase mask containing two regions of opposite phases, with a variable diameter of the inner region. Properly tuning the diameter of the inner region of the mask, the flat-top profile of variable sizes (above and below the subwavelength region) is generated in a controlled manner with the various incident polarization angles of the beam and with the different numerical aperture (NA) value of the lens. Our study reveals that a particular cut-off value of polarization angle, above which the subwavelength flat-top is generated, corresponds to a specific NA that increases with the increase in the NA value. In addition, the emergence of the dual foci structure is observed in the longitudinal direction with increasing NA of the lens. The flat-top's polarization degrees-of-freedom and dual foci properties open up promising routes for potential applications in fluorescence polarization microscopy and multiplane particle trapping.

A new generalized perspective to establish vortex beams

Vortex beams are powerful primitives for optical operations and communications. We propose general mathematical methods to establish new vortex beams and optimize existing vortex beams. Based on these methods, two new types of vortex beams are demonstrated theoretically and experimentally. The propagation characteristics of these vortex beams can be finely controlled through specific parameters. Additionally, influences of periodic discontinuities and orbital angular momentum of two vortex beams are analyzed. The innovative concept of beam modulation and the introduction of new vortex beams in this paper indicate significant potential for applications in particle trapping, spatial communication, and quantum computation.

A brief history and future directions of dielectrophoretic filtration: A review.

Dielectrophoresis (DEP) is an electrokinetic effect first studied in the early 20th century. Since then, DEP has gained significant interest in research, owing to its ability to solve particle separation problems in various industries. Dielectrophoretic filtration (DEP filtration) is a separation method using DEP to filter a wide range of microparticles, from bacterial cells to catalytic particles. DEP filtration can selectively separate particles based on size or dielectric properties, recover trapped particles and avoid common problems associated with mechanical filtration based on pore size (e.g. pressure drops and regular filter replacements). This review describes the simple beginnings of DEP filtration and how our understanding and applications for DEP filtration have progressed over time. A brief section of DEP theory as well as a note on the general outlook for DEP filtration in the future is presented. DEP filtration offers an exciting opportunity to selectively separate diverse particle mixtures. To achieve such a feat, technical challenges such as Joule Heating and low throughputs must be addressed.

Tribological behaviour of laser textured Ti3AlV 2.5V alloy under simulated body fluid

The use of lasers to fabricate micro-textures on the surface of medical implants is an effective method to improve their bio-tribological properties. In the present study, three distinct configurations of micro-textures, namely, co-axial circles, hexagon, and line with varying spacing of 300 µm, 400 µm, and 500 µm, were fabricated on Ti3Al2.5V alloy using Nd:YAG fibre lasers. The influence of micro-textured geometries on microhardness, coefficient of friction (COF), and wear rate was estimated. The tribological properties of the polished and textured samples were investigated using a linear reciprocating tribometer against silicon nitride (Si3N4) balls under simulated body fluid (SBF) lubricant. Orthogonal results indicate that the co-axial circles with a spacing of 305 µm prove to be the most efficient in enhancing the tribological performance of textured surfaces. This configuration demonstrates a significant improvement, with a 33.62 % reduction in friction coefficient and a 61.81 % reduction in wear rate compared to polished samples. The decrease in spacing appears to enhance the anti-friction and anti-wear properties of the textured surfaces. The working mechanism behind the reduction in the friction coefficient and wear rate lies in the capacity of the textures to trap particles.

Particle manipulation based on the controllable light field of graphene nano-butterfly structures

In this Letter, we have proposed a nano-optical convey belt consisting of three sets of graphene nano-butterfly structures (GNBS) with different lengths arranged in a periodic pattern to trap, transport, and sort particles depending on controlling the Fermi level of graphene. The graphene nano-butterfly structure, based on a couple of trapezoids, can form a potential well to capture particles by localized surface plasmon resonance under the excitation of an incident laser. There are three adjustable geometric parameters containing width (W1, W2) and length (L) that make the GNBS have a high degree of design flexibility. Graphene can support surface plasmons in the mid-infrared region, and at the same time, it possesses a more flexible tuning mechanism compared to metals. When the incident light power is 1 mW/μm2 and the resonance wavelength is 10.6 μm, the depth of the potential well is greater than 10KbT for 50 nm particles. Moreover, the sorting of particles with different diameters has also been validated under appropriate power and switching time. Based on the capabilities of capture and sorting verified by numerical analysis, our design offers a new scheme for on-chip optofluidic applications.

Study of Plasma Flow Velocity in an Open SMOLA Screw Trap

The physics of confinement of a rotating plasma in a magnetic field with linear helical symmetry is being studied at the Institute of Nuclear Physics SB RAS on the open SMOLA trap. An indicator of the quality of confinement is the plasma flow velocity in the system. The paper describes the applied diagnostics based on the Mach probe under conditions of non-magnetized plasma, which made it possible to determine the longitudinal flow velocity in experiments. The measured longitudinal flow velocity was (0.5–5) · 106 cm/s in various operating modes of the installation. The dependence of the speed on the magnitude of the magnetic field corrugation is discussed. A reverse flow of trapped particles returning to the containment zone has been detected.