External Medium Research Articles

Modeling of Long-term Afterglow Counterparts to Gravitational Wave Events: The Full View of GRB 170817A

The arrival of gravitational wave astronomy and a growing number of time-domain-focused observatories are set to lead to an increasing number of detections of short gamma-ray bursts (GRBs) launched with a moderate inclination to Earth. Being nearby events, these are also prime candidates for very long-term follow-up campaigns and very long-baseline interferometry, which has implications for multi-messenger modeling, data analysis, and statistical inference methods applied to these sources. Here, we present a comprehensive modeling update that directly incorporates into afterglowpy astrometric observations of the GRB position, Poissonian statistics for faint sources, and modeling of a trans-relativistic population of electrons. We use the revolutionary event GW170817 to demonstrate the impact of these extensions both for the best-fit physics parameters and model selection methods that assess the statistical significance of additional late-time emission components. By including in our analysis the latest Chandra X-ray observations of GRB 170817A, we find only weak evidence (≲2σ) for a new emission component at late times, which makes for a slightly more natural fit to the centroid evolution and prediction for the external medium density.

Ultra-efficient surface grating couplers for chip-to-fiber and chip-to-free-space coupling based on single-beam radiation

Surface grating couplers, such as fiber-chip grating couplers and optical antennas, are fundamental devices in photonic integrated circuits, as they enable the coupling of light between the chip and an external medium. An important metric of surface grating couplers is the coupling efficiency, and high values, greater than -1 dB, are required for applications in quantum technology, light detection and ranging, and optical interconnects. Surface grating couplers typically suffer from radiation loss to the substrate, which significantly limits their coupling efficiency. Here we propose a novel grating-coupling concept that utilizes a high-refractive-index upper cladding to frustrate radiation orders to the substrate by operating in a single-beam diffraction regime. To illustrate this concept, we report the design of an easily fabricable silicon surface grating coupler with an unprecedented coupling efficiency of -0.2 dB to a single-mode optical fiber. Furthermore, the proposed strategy allows us to design an evanescently coupled millimeter-long optical antenna with a coupling efficiency of -0.1 dB to free space. Additionally, an ultra-fast wavelength-tunable beam steering of 0.37°/nm is achieved, which corresponds to more than a 2.5-fold enhancement over comparable silicon antennas. These results represent a pathway for a new set of photonic integrated interfaces for applications in which high-efficiency chip-to-fiber and chip-to-free-space coupling is critical.

The influence of second-order metacognitive judgments on cognitive offloading within the monitoring-control relationship

Cognitive offloading refers to using an external medium such as paper to remember information rather than relying solely on memory. Previous research has suggested that individuals’ perceived memory performance may influence their decision to employ cognitive offloading as a learning strategy. However, ubiquitous distortions in metacognitive judgments limit the learning gains. Motivated by this, the current study incorporated second-order metacognitive judgments (SOJs) with distorted first-order metacognitive judgments (FOJs) within a learning context that allowed cognitive offloading. We investigated how individuals decide to employ cognitive offloading based on two levels of self-assessments. Eighty participants from the U.S. were recruited remotely to complete online paired-associate tasks. They learned 48 paired associates on an item-by-item basis, providing a FOJ, an SOJ, and a strategy (offload or not) on each trial. Our findings showed a significant effect of interaction between FOJs and SOJs on the selection of cognitive offloading. Additionally, there were significant variabilities in employing cognitive offloading across individual participants and word pairs. We concluded that SOJs influence the association between FOJs and strategy choices. Furthermore, we attributed the observed interaction to the assessment and regulation of SOJ about FOJ.

Performance of the edible halophyte Cakile maritima under critical magnesium and potassium thresholds

In their natural biotope, plants are challenged with low nutrient availability which is one of the most important limiting factors for plant production. Nutrient limitation causes disruption in several metabolic pathways resulting in a decrease in plant growth and establishment. Such responses were mostly studied in glycophytes while in halophytes the data remained scare. In the present investigation, using Cakile maritima as a plant model for halophytes, we attempt to elucidate the behavior of this species under critical magnesium and potassium thresholds. Our data showed that low K or Mg supply (0.01 mM) reduced leaf number and biomass production in leaves, stems and roots while both parameters were improved at 0.05 mM Mg and K concentration before reaching an optimum at 0.25 mM Mg and 1 mM K, respectively. Several indices of K and Mg stress tolerance were reduced upon deficiency in both elements and were significantly improved by moderate K and Mg supply. Photosynthetic pigment content was reduced upon both deficiencies with the highest reductions recorded in plants suffering from severe Mg and K starvation. Increasing Mg and K supply resulted in better chlorophyll synthesis as reflected by the increase in chlorophyll stability index parameter (CSI). Furthermore, both deficiencies triggered oxidative damages as malondialdehyde content (MDA) and electrolyte leakage (EL) increased while membrane stability index (MSI) decreased under both deficiencies. Such results suggested that the cell redox homeostasis was altered when Mg and K were omitted from the nutrient solution. Interestingly, moderate and high Mg and K concentrations promoted C. maritima growth and reduced the oxidative damage caused by the lack of both elements in the external medium. Overall, C. maritima exhibited a typical halophytic behaviour, requiring less macroelements to express its growth performance when cultivated under critical magnesium and potassium thresholds.

Failure Analysis of Corrosion Pit on Outer Wall of Membrane Wall Pipe

Abstract Flue gas pipework is a critical component of a flue gas treatment system, mainly transporting the flue gases produced by a combustion plant from the source to the vent. Flue gas pipework is vital in all applications, such as thermal storage gas stoves, heaters, and gas water heaters. However, due to negligent management during the use of piping. Corrosion pits were created in several places on the outer wall of a membrane wall pipe located on the flue gas side of the membrane wall pipe. The external circulation medium of the membrane wall pipe is mainly high-temperature flue gas, and the internal circulation medium is water. This paper determines the causes of the corrosion pits by macroscopic observation, metallographic microstructure analysis, scanning electron microscopy, and energy dispersive spectroscopy (EDS). It was found that the outer wall of the flue gas sidewall pipe of the failed part was covered with reddish-brown rust, wide and shallow corrosion pits were observed, and the detection area of the inner surface of the pits had a high ‘S’ content. To reiterate, it was concluded that the cause of the corrosion pits was the flue gas dew-point corrosion.

Selenate simultaneously alleviated cadmium and arsenic accumulation in rice (Oryza sativa L.) via regulating transport genes

Cadmium (Cd) and arsenic (As) have contrasting biogeochemical behaviors in paddy soil, which posed an obstacle for reducing their accumulation in rice (Oryza sativa L.) simultaneously. In this study, selenate exhibited a more effective ability than selenite on simultaneous alleviation of Cd and As accumulation in rice under Cd-As co-exposure, and the mechanisms need to be further investigated. The results showed that selenate significantly decreased the root Cd and As contents by 59%–83% and 43%–72% compared to Cd-As compound exposure, respectively. Correspondingly, it significantly down-regulated the expression of uptake-related genes OsNramp5 (87.1%) and OsLsi1 (95.5%) in rice roots. Decreases in Cd (64.5%) and As (16.2%) contents in shoots were also found after selenate addition. Moreover, selenate may promoted the reduction of As(V) to As(Ⅲ) and As(III) efflux to the external medium, resulting in decreased As accumulation and As(Ⅲ) proportion in rice shoots and roots. In addition, selenate could promote the binding of Cd (by 14%–24%) and As (by 9%–15%) in the cell wall, and significantly reduced the oxidative stress by elevating levels of antioxidant enzymes (by 10%–105%) and thiol compounds (by 6%–210%). Additionally, selenate significantly down-regulated the expression of OsNramp1 (49.3%) and OsLsi2 (82.1%) associated with Cd and As transport in rice. These findings suggest selenate has the potential to be an effective material for the simultaneous reduction of Cd and As accumulation in rice under Cd-As co-contamination.

Jet collimation and acceleration in the flat spectrum radio quasar 1928+738

Using time-resolved multifrequency Very Long Baseline Array data and new KaVA (KVN and VERA Array) observations, we study the structure and kinematics of the jet of the flat spectrum radio quasar (FSRQ) 1928+738. We find two distinct jet geometries as a function of distance from the central black hole, with the inner jet having a parabolic shape, indicating collimation, and the outer jet having a conical shape, indicating free expansion of the jet plasma. Jet component speeds display a gradual outward acceleration up to a bulk Lorentz factor Γmax ≈ 10 followed by a deceleration further downstream. The location of the acceleration zone matches the region where the jet collimation occurs. Therefore, this is the first direct observation of an acceleration and collimation zone (ACZ) in an FSRQ. The ACZ terminates approximately at a distance of 5.6 × 106 gravitational radii, which is in good agreement with the sphere of gravitational influence of the supermassive black hole, implying that the physical extent of the ACZ is controlled by the black hole gravity. Our results suggest that confinement by an external medium is responsible for the jet collimation and that the jet is accelerated by converting Poynting flux energy to kinetic energy.

Non-linear torsional Alfv\'en waves evolving in stratified viscous plasmas: Coronal hole plumes

We model solar atmospheric structures characterised by parallel structuring. We focus on Alfv\'en waves in the weakly non-linear regime to highlight the efficiency of non-linear wave steepening when dissipative effects are prominent. We also consider the local and equilibrium conditions involved in shock formation and the shock's contributions to coronal seismology. Coronal plumes were modelled analytically by implementing the magnetohydrodynamic (MHD) theory in cylindrical geometry. Here, the stratification and viscosity are present internal to the plume, whilst effects of the external medium, together with equilibrium conditions, are implied where the magnetic fields are parallel to the plume axis. We implemented a second-order thin flux tube approximation to obtain a wave equation that points to effects tied to non-linear, dissipative, and stratification terms, as well as terms representing atmospheric conditions. The impact of shear viscosity on non-linear Alfv\'en waves extracted by the Cohen-Kulsrud-Burgers-type equation proves more efficient when propagated to higher altitudes. The dissipative effects linked to the dimensionless viscosity indicate that the dissipative effects are not linear. Meanwhile, the delay in shock formation enables energy conversions at higher altitudes, thereby maintaining coronal heating at higher levels. The efficiency of parallel structuring and viscous damping is enhanced by such transverse structuring, as it is directly proportional to the external plasma-beta . It is observed that Alfv\'en pulses may undergo a backward shock, either in the lower levels of coronal plasma or as they propagate toward higher regions, implying a conversion of energy occurring at various altitudes. A peak was observed, indicating that the interplay reverses at heights around $1.5$ solar radii. Such effects are shown to play a key role in the context of coronal seismology.

Exciting Surface Plasmon Resonances on Gold Thin Film‐Coated Optical Fibers Through Nanoparticle Light Scattering

AbstractSurface plasmon resonance (SPR) conventionally occurs at the interface of a thin metallic film and an external dielectric medium in fiber optics through core‐guided light. However, this work introduces theoretical and experimental evidence suggesting that the SPR in optical fibers can also be induced through light scattering from Au nanoparticles (NPs) on the thin metallic film, defined as nanoparticle‐induced SPR (NPI‐SPR). This method adheres to phase‐matching conditions between SPR dispersion curves and the wave vectors of scattered light from Au NPs. Experimentally, these conditions are met on an etched optical fiber, enabling direct interaction between light and immobilized Au NPs. Compared to SPR, NPI‐SPR exhibits stronger field intensity in the external region and wavelength tuning capabilities (750 to 1250 nm) by varying Au NP diameters (20 to 90 nm). NPI‐SPR demonstrates refractive index sensitivities of 4000 to 4416 nm per refractive index unit, nearly double those of typical SPR using the same optical fiber configuration sans Au NPs. Additionally, NPI‐SPR fiber configuration has demonstrated its applicability for developing biosensors, achieving a remarkable limit of detection of 0.004 nm for thrombin protein evaluation, a twenty‐fold enhancement compared to typical SPR. These findings underscore the intrinsic advantages of NPI‐SPR for sensing.

Exogenous Sodium Nitroprusside Affects the Redox System of Wheat Roots Differentially Regulating the Activity of Antioxidant Enzymes under Short-Time Osmotic Stress.

Nitric oxide (NO) is a multifunctional signalling molecule involved in the regulation of plant ontogenesis and adaptation to different adverse environmental factors, in particular to osmotic stress. Understanding NO-induced plant protection is important for the improvement of plant stress tolerance and crop productivity under global climate changes. The root system is crucial for plant survival in a changeable environment. Damages that it experiences under water deficit conditions during the initial developmental periods seriously affect the viability of the plants. This work was devoted to the comparative analysis of the pretreatment of wheat seedlings through the root system with NO donor sodium nitroprusside (SNP) for 24 h on various parameters of redox homeostasis under exposure to osmotic stress (PEG 6000, 12%) over 0.5-24 h. The active and exhausted solutions of SNP, termed as (SNP/+NO) and (SNP/-NO), respectively, were used in this work at a concentration of 2 × 10-4 M. Using biochemistry and light microscopy methods, it has been revealed that osmotic stress caused oxidative damages and the disruption of membrane cell structures in wheat roots. PEG exposure increased the production of superoxide (O2•-), hydrogen peroxide (H2O2), malondialdehyde (MDA), and the levels of electrolyte leakage (EL) and lipid peroxidation (LPO). Stress treatment enhanced the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), the excretion of proline, and the rate of cell death and inhibited their division. Pretreatment with (SNP/+NO) decreased PEG-induced root damages by differently regulating the antioxidant enzymes under stress conditions. Thus, (SNP/+NO) pretreatment led to SOD, APX, and CAT inhibition during the first 4 h of stress and stimulated their activity after 24 h of PEG exposure when compared to SNP-untreated or (SNP/-NO)-pretreated and stress-subjected plants. Osmotic stress triggered the intense excretion of proline by roots into the external medium. Pretreatment with (SNP/+NO) in contrast with (SNP/-NO) additionally increased stress-induced proline excretion. Our results indicate that NO is able to mitigate the destructive effects of osmotic stress on the roots of wheat seedlings. However, the mechanisms of NO protective action may be different at certain periods of stress exposure.

Failure analysis of stress corrosion cracking in welded structures of aluminum alloy metro body traction beam in service

A comprehensive failure analysis was carried out for a crack appearing in the welded structure of an aluminum alloy body traction beam in a service metro vehicle. The fracture composition analysis reveals the products remaining after the reaction between the external corrosive medium and the material. A three-dimensional finite element model of the welded area of the traction beam was further established to simulate the high residual tensile stress present in the welded area. Based on the dynamic stress testing, it was found that the external loads had little effect on their crack growth. A series of analyses based on material properties, microstructure, fracture morphology and residual stresses identified stress corrosion as the leading cause of crack growth failure. Finally, a new structural repair program is proposed, and the reliability of the new structure in service life is verified by comparison, avoiding catastrophic fracture accidents in the service structure.

A semi-analytical model for the propagation of a relativistic jet in a magnetized medium

ABSTRACT The merger of two magnetized compact objects, such as neutron stars, forms a compact object which may launch a relativistic and collimated jet. Numerical simulations of the process show that a dense and highly magnetized medium surrounds the system. This study presents a semi-analytical model that models the effects that a static magnetized medium with a tangled field produces in relativistic, collimated, and non-magnetized jets. The model is a first approximation that addresses the magnetic field present in the medium and is based on pressure equilibrium principles between the jet, cocoon, and external medium. A fraction of the ambient medium field is allowed to be entrained in the cocoon. We find that the jet and cocoon properties may be affected by high magnetic fields (≳ 1015 G) and mixing. The evolution of the system may vary up to $\sim 10{{\ \rm per\ cent}}$ (compared to the non-magnetized case). Low-mixing may produce a slower broader jet with a broader and more energetic cocoon would be produced. On the other hand, high-mixing could produce a faster narrower jet with a narrow and less-energetic cocoon. Two-dimensional hydrodynamical simulations are used to validate the model and to constrain the mixing parameter. Although the magnetic field and mixing have a limited effect, our semi-analytic model captures the general trend consistent with numerical results. For high magnetization, the results were found to be more consistent with the low mixing case in our semi-analytic model.

Monitoring of Curing Process of Epoxy Resin by Long-Period Fiber Gratings.

The curing of epoxy resin is a complex thermo-chemical process that is difficult to monitor using existing sensing systems. We monitored the curing process of an epoxy resin by using long-period fiber gratings. The refractive index of the epoxy resin increases during the curing process and can be measured to determine the degree of curing. We employed long-period fiber gratings that are sensitive to the refractive index of an external medium for the measurement of refractive index changes in the resin. We observed that the resonances of long-period fiber gratings increased their depth with the increased refractive index of the resin, which was well described by our simulation taking the coupling to radiation modes into account. We demonstrated that the degree of cure can be estimated from the depth of the grating resonances using a phenomenological model. At the same time, long-period fiber gratings are sensitive to temperature variations and internal strains that are induced during curing. These factors may affect the measurements of curing degree and should also be addressed.

Self-similarity of the third type in ultra-relativistic blastwaves

A new type of self-similarity is found in the problem of a plane-parallel, ultra-relativistic blastwave, propagating in a power-law density profile of the form ρ∝z−k. Self-similar solutions of the first kind can be found for k < 7∕4 using dimensional considerations. For steeper density gradients with k > 2, second type solutions are obtained by eliminating a singularity from the equations. However, for intermediate power-law indices 7/4<k<2, the flow does not obey any of the known types of self-similarity. Instead, the solutions belong to a new class in which the self-similar dynamics are dictated by the non-self-similar part of the flow. We obtain an exact solution to the ultra-relativistic fluid equations and find that the non-self-similar flow is described by a relativistic expansion into vacuum, composed of (1) an accelerating piston that contains most of the energy and (2) a leading edge of a fast material that coincides with the interiors of the blastwave and terminates at the shock. The dynamics of the piston itself are self-similar and universal and do not depend on the external medium. The exact solution of the non-self-similar flow is used to solve for the shock in the new class of solutions.

Scaling relations for gamma-ray burst afterglow light curves and centroid motion independent of jet structure and dynamics

ABSTRACT Models for gamma-ray burst afterglow dynamics and synchrotron spectra are known to exhibit various scale invariances, owing to the scale-free nature of fluid dynamics and the power-law shape of synchrotron spectra. Since GRB 170817A, off-axis jet models including a lateral energy structure in the initial outflow geometry have gained in prominence. Here, we demonstrate how the scale invariance for arbitrary jet structure and dynamical stage can be expressed locally as a function of jet temporal light-curve slope. We provide afterglow flux expressions and demonstrate their use to quickly assess the physical implications of observations. We apply the scaling expressions to the Swift X-ray Telescope sample, which shows a spread in observed fluxes, binned by light-curve slope at time of observation, that increases with increasing light-curve slope. According to the scaling relations, this pattern is inconsistent with a large spread in environment densities if these were the dominant factor determining the variability of light curves. We further show how the late deep Newtonian afterglow stage remains scale-invariant but adds distinct spectral scaling regimes. Finally, we show that for given jet structure a universal curve can be constructed of the centroid offset, image size, and ellipticity (that can be measured using very large baseline interferometry) versus observer angle, in a manner independent of explosion energy and circumburst density. Our results apply to any synchrotron transient characterized by a release of energy in an external medium, including supernova remnants, kilonova afterglows, and soft gamma-repeater flares.

A tale of two pumps: Blue light and abscisic acid alter Arabidopsis leaf hydraulics via bundle sheath cell H+-ATPases.

The bundle sheath cell (BSC) layer tightly enveloping the xylem throughout the leaf is recognized as a major signal-perceiving "valve" in series with stomata, regulating leaf hydraulic conductance (Kleaf) and thereby radial water flow via the transpiring leaf. The BSC blue light (BL) signaling pathway increases Kleaf and the underlying BSC water permeability. Here, we explored the hypothesis that BSCs also harbor a Kleaf-downregulating signaling pathway related to the stress phytohormone abscisic acid (ABA). We employed fluorescence imaging of xylem sap in detached leaves and BSC protoplasts from different genotypes of Arabidopsis (Arabidopsis thaliana) plants, using pH and membrane potential probes to monitor physiological responses to ABA and BL in combination with pharmacological agents. We found that BL-enhanced Kleaf required elevated BSC cytosolic Ca2+. ABA inhibited BL-activated xylem-sap-acidifying BSC H+-ATPase AHA2 (Arabidopsis H+-ATPase 2), resulting in depolarized BSCs and alkalinized xylem sap. ABA also stimulated BSC vacuolar H+-ATPase (VHA), which alkalinized the BSC cytosol. Each pump stimulation, AHA2 by BL and VHA by ABA (under BL), also required Ca2+. ABA stimulated VHA in the dark depending on Ca2+, but only in an alkaline external medium. Taken together with earlier findings on the pH sensitivity of BSC osmotic water permeability (i.e. aquaporin activity), our results suggest a Ca2+-dependent and pH-mediated causative link between the BL- and ABA-regulated activities of two BSC H+-ATPases and Kleaf.

Intraphagosomal Free Ca2+ Changes during Phagocytosis.

Phagocytosis (and endocytosis) is an unusual cellular process that results in the formation of a novel subcellular organelle, the phagosome. This phagosome contains not only the internalised target of phagocytosis but also the external medium, creating a new border between extracellular and intracellular environments. The boundary at the plasma membrane is, of course, tightly controlled and exploited in ionic cell signalling events. Although there has been much work on the control of phagocytosis by ions, notably, Ca2+ ions influxing across the plasma membrane, increasing our understanding of the mechanism enormously, very little work has been done exploring the phagosome/cytosol boundary. In this paper, we explored the changes in the intra-phagosomal Ca2+ ion content that occur during phagocytosis and phagosome formation in human neutrophils. Measuring Ca2+ ion concentration in the phagosome is potentially prone to artefacts as the intra-phagosomal environment experiences changes in pH and oxidation. However, by excluding such artefacts, we conclude that there are open Ca2+ channels on the phagosome that allow Ca2+ ions to "drain" into the surrounding cytosol. This conclusion was confirmed by monitoring the translocation of the intracellularly expressed YFP-tagged C2 domain of PKC-γ. This approach marked regions of membrane at which Ca2+ influx occurred, the earliest being the phagocytic cup, and then the whole cell. This paper therefore presents data that have novel implications for understanding phagocytic Ca2+ signalling events, such as peri-phagosomal Ca2+ hotspots, and other phenomena.

A WGM-FP hybrid microcavity for simultaneous measurement of NaCl concentration and temperature

Whispering gallery mode (WGM) resonator is sensitive to the external medium change due to its strong light-matter interaction. However, the temperature sensitivity of silica-based WGM resonators would cause crosstalk, which is a fatal shortcoming for those high-quality (Q) resonators. In this paper, a hybrid microcavity including WGM resonance and Fabry–Pérot (FP) interference is proposed for simultaneous measurement of NaCl concentration and temperature, using the same microcavity in the same system to obtain two types of optical signals. The experimental results indicate that the maximum measurement error of NaCl concentration and temperature without compensation is about ± 0.026 % and ± 1.1 °C, while they would be ± 0.012 % and ± 0.3 °C after compensation. Sharing one microcavity enables temperature compensation to achieve temperature synchronization, and sharing of one system ensures the simplicity and stability of the sensing platform.

Magneto-optical-like effect in tight focusing of azimuthally polarized sine-Gaussian beams.

Magneto-optical effects, which have been known for over a century, are among the most fundamental phenomena in physics and describe changes in the polarization state of light when it interacts with magnetic materials. When a polarized plane wave propagates in or through a homogeneous and isotropic transparent medium, it is generally accepted that its transverse polarization structure remains unchanged. However, we show that a strong radial polarization component can be generated when an azimuthally polarized sine-Gaussian plane wave is tightly focused by a high numerical aperture lens, resulting in a magneto-optical-like effect that does not require external magnetic field or magnetic medium. Calculations show that the intensity structure and polarization distribution of the highly confined electric field strongly depend on the parameters m and φ0 in the sinusoidal term, where m can be used to control the number of the multifocal spots and φ0 can be used to control the position of each focal spot. Finally, we show that this peculiar electric field distribution can be used to realize multiple particles trapping with controllable numbers and locations.

Assessment of sulfamethoxazole removal by three wetland plant species under hydroponic conditions: uptake, accumulation, and physiological responses

Plants play a crucial role as a removal pathway in constructed wetlands, demonstrating the ability to absorb and tolerate antibiotics from wastewater. However, the specific contribution of plants in this regard has not yet to be sufficiently established. To gain a more comprehensive insight into the associated processes, we selected three common wetland plant species, Canna indica L. (C. indica), Cyperus alternifolius L. (C. alternifolius), and Thalia dealbata Fraser (T. dealbata), to evaluate their capacity for uptake, accumulation, and physiological response in the removal of sulfamethoxazole (SMX) at varying initial concentrations (10, 30, 100, and 300 µg/L) under hydroponic conditions. The results showed that SMX removal was more efficient at lower concentrations (10 and 30 µg/L) than at higher concentrations (100 and 300 µg/L). Moreover, plant systems were found to consistently outperform unplanted systems in SMX removal. Among the assessed species, C. indica was identified as being relatively effective in the removal of SMX, whereas the performance of C. alternifolius was notably less pronounced. A positive correlation was observed between the concentration of SMX in the plant tissues and that in the external aqueous medium. However, plant tissue residues contributed only a minor fraction to the overall removal of SMX. Wetland plants absorb SMX through their roots, and we accordingly detected significantly higher concentrations in submerged plant tissues. Furthermore, we also detected reductions in net photosynthetic rates indicative of potential phytotoxicity, which is associated with the accumulation of antibiotic in the shoot tissues. Accumulation of SMX in the roots and rhizomes was also found to be associated with the development of shorter roots, with this effect becoming more pronounced with an increase in the concentration of exogenous SMX. However, despite these adverse effects, plants can detoxify antibiotics via the glutathione pathway. Of the assessed plant species, C. indica was identified as the most SMX tolerant, as indicated by K m and V max values, with C. alternifolius being the least tolerant. Our findings in this study reveal the potential value of wetland plants in the sequestration of antibiotics and provide evidence for the underlying mechanisms of action. These findings could make an important contribution to the implementation of phytoremediation in antibiotic-contaminated water.