Direct Field Research Articles

Low-Energy Photoresponsive Magnetic-Assisted Cleaning Microrobots for Removal of Microplastics in Water Environments.

In the global ecosystem, microplastic pollution pervades extensively, exerting profound and detrimental effects on marine life and human well-being. However, conventional removal methods are usually limited to chemical flocculation and physical filtration but are insufficient to remove extremely small microplastics. Therefore, developing a comprehensive strategy to address the threat posed by microplastics is imperative. Here, we report a low-energy photoresponsive magnetic-assisted cleaning microrobot (LMCM) composed of photocatalytic material (Ag@Bi2WO6) and magnetic nanoparticles (Fe3O4), which can be used for the active removal of microplastics from water environments. Due to the diffusion electrophoresis effect, the low-energy photoresponsive cleaning microrobots (LCMs) are formed by spontaneous assembly of Ag@Bi2WO6, which can continuously adsorb microplastics in a water environment. Particularly, the effective attraction distance of LCMs on microplastics exceeds 100 μm. After assembling the Fe3O4 nanoparticles, LMCMs can clean microplastics in groups from water environments under the control of a magnetic field. Utilizing precision manipulation and group control, LMCMs demonstrate a remarkable 98% cleaning efficiency in 93 s and can be recovered under the control of the directional magnetic field. This eco-friendly and energy-efficient microrobot is expected to provide a viable strategy to tackle the threat of microplastics or promote industrial microplastic removal.

Study on the Interface Reinforcement Effect of Bamboo Grid in Filled Loess Embankment in a High and Steep Gully

A bamboo grid is a new type of reinforcement material, which can replace traditional geogrids in the reinforcement of embankments. In this study, the reinforcement effect of the bamboo grid that is only set at the interface between the filled and undisturbed soils of the filled loess embankment in a high and steep gully was investigated. The influence of reinforcement position and grid spacing on the reinforcement effect was studied by carrying out a large-scale direct shear test, numerical simulation, and field measurement. The results indicated that the bamboo grid could enhance the shear strength of the reinforcement interface. The interface shear strength first improved and then decreased with the decrease in grid spacing. The differential settlement was significantly reduced after the reinforcement of the bamboo grid at the interface. Compared with other reinforcement positions, setting the bamboo grid in the upper part of the embankment was the most efficient and economical. When the grid spacing became dense, the reinforcement effect was improved as the differential settlement decreased. However, the improvement in the reinforcement effect by decreasing the grid spacing was limited, which meant there was an optimal grid spacing.

Pilgrimage Tourism to Wali Tombs and Halal Destination Management Based on Sharia Values

This study explores the relationship between pilgrimage tourism to Wali tombs and halal tourism, focusing on the integration of Sharia values in the management of religious destinations. In the context of East Java, this research examines the application of Sharia principles by site managers to maintain the sanctity and integrity of the sites, as well as its impact on the experience of Muslim tourists. The study uses a qualitative approach with a case study method. Data were collected through in-depth interviews with site managers, tourists, and local communities, along with direct field observations. The findings show that the application of Sharia management in site operations not only enhances tourist satisfaction but also strengthens the local economy and cultural preservation. However, the study also found a lack of understanding of Sharia values among some site managers. This research provides recommendations for site managers to create tourist destinations aligned with Sharia principles, supporting the growth of halal tourism in Indonesia. It is hoped that the results of this study can serve as a reference for developing policies on sustainable and responsible religious tourism.This study has several limitations, including the geographical scope limited to East Java and restricted access to all pilgrimage site managers. Therefore, the findings cannot be generalized to all religious tourism destinations in Indonesia. Further research covering a broader area is recommended to enrich the findings.

Response of hibiscus mealybug (Hemiptera: Pseudococcidae) to citrus volatiles induced by mechanical injury.

Hibiscus mealybug, Nipaecoccus viridis (Newstead) (Hemiptera: Pseudococcidae), is a recent invasive pest of citrus and many other crops in Florida. Nipaecoccus viridis attacks all above ground parts of citrus trees and heavy infestation can cause leaf drop and premature abortion of developing fruits. We quantified greater captures of N. viridis in cardboard band traps on areas of citrus trees that were intentionally injured by mechanical rasping of epidermal tissues as compared with similar but uninjured citrus branches. Direct field collection of headspace volatiles from mechanically injured or intact citrus branches revealed both qualitative and quantitative differences. Certain volatiles (γ-terpinene, citronellal, citronellyl acetate, β-E-farnesene, α-humulene, and α-E-E-farnesene) were only present in samples from damaged citrus branches. Behavioral assays using a laboratory Y-tube olfactometer revealed attraction of N. viridis to volatiles associated with mechanical damage of citrus including synthetic β-ocimene, γ-terpinene, sabinene, isomers of farnesene, and citronellal when loaded into lures at either of 2 concentrations (0.01 or 0.1 µg/µl). Subsequent field trapping experiments confirmed increased captures of various life stages of N. viridis in cardboard band traps baited with a 10.0 µg/µl concentration of farnesene:ocimene:sabinene blend (in 7:13:17 ratio), as well as those releasing either farnesene or ocimene alone at this same concentration, as compared with the mineral oil (diluent) negative control. Our results indicate that common plant related terpenes released by citrus following mechanical damage may be useful for development of an effective monitoring trap for N. viridis.

Design of Scheduled Fog Irrigation System with ESP 32 in Mustard Seedbed (Brassica juncea L.)

Plants receive water from the fog irrigation system in the form of tiny, mist-like water particles. Currently, irrigation technology has advanced, nurseries can be automatically irrigated. In this research, the ESP32 microcontroller is used to create the electronic circuits for the automation of the fog irrigation control system in a mustard green nursery. This study's methodology combines direct field observation with an experimental or trial approach. Water flow (ml/minute), water use efficiency (%), plant height (cm), number of leaves, and scheduled fog irrigation system performance are among the measured parameters. In this investigation, four different treatments were used: manual irrigation using a watering can, two-time, three-time, and one-time irrigation. All is going according to plan with this mist watering system. With an average height of 4.58 cm and an average number of leaves of 3.24, the mist irrigation system had the highest water use efficiency of 77.35% during the test. It was also found that mist irrigation produced the highest amount of mustard leaves in the three-times-per-day treatment. Keywords: ESP32, Fog irrigation, Green mustard, Nurseries.

Terahertz laser-fabricated all-polymer hole arrays with high-quality quasi-bound states in the continuum

Abstract Dielectric metasurfaces promise to realize ultrahigh-quality (Q) resonances due to their ultralow material absorption. Most of them are silicon-based metasurfaces, requiring complex fabricated steps and thus suffering high costs. Laser etching processing has simple steps accompanied by low time consumption and exemplary processing efficiency. Here, an all-polymer metasurface based on hole arrays fabricated by laser processing has been proposed and investigated. Such metasurfaces achieve sharp quasi-bound states in the continuum (quasi-BICs) via breaking structural symmetry, form two annular circulation electric fields in different directions, and thus allow strong coupling between holes. Owing to the low refractive index of polymer, the calculated Q-factor reaches 9555 while the diameter discrepancy is 4 μm. Simulated results proved that the Q-factors of quasi-BICs can be further improved by reducing the film thickness and refractive indices of materials, which can be predicted by the fitting equation. Also, the fields in holes can be enhanced by reducing the film refractive index. These results in simulations and experiments provide an alternative method for designing high-Q resonators in terahertz regions.

Enhanced electro-optic modulation stability in KTa1−xNbxO3 crystal by direct current electric field

Enhanced electro-optic modulation stability in KTa1−xNbxO3 crystal by direct current electric field

Lamb Wave TDTE Super-Resolution Imaging Assisted by Deep Learning

Abstract Ultrasonic Lamb waves undergo complex mode conversion and diffraction at non-penetrating defects, such as plate corrosion and cracks. Lamb wave imaging has a resolution limit due to the guided wave dispersion characteristics and Rayleigh criterion limitations. In this paper, a full convolutional network is designed to segment and reconstruct the received signals, enabling the automatic identification of target modalities. This approach eliminates clutter and mode conversion interference when calculating direct and accompanying acoustic fields in time-domain topological energy imaging. Subsequently, the measured accompanying acoustic field is reversed for adaptive focusing on defects and enhance the imaging quality. To circumvent the limitations of the Rayleigh criterion, the direct acoustic field and the accompanying acoustic field were fused to characterize the pixel distribution in the imaging region, achieving Lamb wave super-resolution imaging. Experimental results indicate that compared to the sign coherence factor-total focusing method (SCF-TFM), the proposed method achieves a 31.41% improvement in lateral resolution and a 29.53% increase in signal-to-noise ratio for single-blind-hole defects. In the case of multiple-blind-hole defects with spacings greater than the Rayleigh criterion resolution limit, it exhibits a 27.23% enhancement in signal-to-noise ratio. On the contrary, when the defect spacings are relatively smaller than the limit, this method has a higher resolution limit than SCF-TFM in super-resolution imaging.

Electro-phytoremediation of polluted soil at pilot level using maize

This article presents the imposition of a direct current electric field in the presence of seeds and plants of Zea mays L., to rehabilitate soils contaminated with hydrocarbons at a pilot level, and its influence on some physical and chemical properties of the soil, such as pH, electrical conductivity, organic matter content in the soil, enzymatic activity, bulk density, apparent density, porosity, cation exchange capacity, and soluble cations such as potassium, sodium, and calcium. For this reason, the edaphological characterization was carried out before and after an electro-phytoremediation process of soils contaminated with hydrocarbons, using an IrO2-Ta2O5|Ti anode and a titanium cathode, applying a constant electric field of 0.2 V/cm for 4 h to maize seeds and stimulating their germination. After one week, an electric field of 0.1 V/cm for 8 h was applied to the maize seeds every day for 42 days to stimulate the growth of maize plants. This study demonstrated the removal of hydrocarbons by electro-phytoremediation. The applied electric field increases seed germination and plant growth of Zea mays L. These results were obtained with the different transport phenomena that develop when using the electric field in the soil Vertisol pelic understudy at a pilot level.

Static and dynamic open loop control of selective laser flash sintering conducted with direct current electric fields

AbstractSelective laser flash sintering utilizes a scanning laser as a heat source to locally initiate flash sintering in the regions scanned by the laser. A key challenge towards utilizing this process for additive manufacturing (AM) is the induced electrical current that arises during flash sintering. With traditional scan patterns conducted with static electric fields, electrical and thermal runaway and associated thermal shock cracking occur. In this study, several open‐loop control strategies with static and dynamic applied electric fields were utilized to control peak currents. These strategies were shown to be effective in reducing peak currents to below 1.0 µA and reducing the severity of, but not completely eliminating cracking. Alternative strategies are suggested that could lead to complete elimination of cracks.

Electrocombustion Characteristics of Iron Particle-Laden Methanol and Ethanol Droplets in a Direct Current Field

ABSTRACT This study investigates the electrocombustion and atomization behavior of single droplets (2.5 wt.% Fe) of ethanol (EtOH) and methanol (MeOH) fuels at the droplet scale. The experiments utilize a system with two opposing plate electrodes of varying distances (200, 150, and 100 mm) and both negative (↓) and positive (↑) polarizations within a vertical direct current (DC) electric field. The results show that for EtOH and EtOH/Fe droplets, the flame envelope changes to a spherical form at (↓) and (↑) polarizations at 100 mm plate spacing, while for MeOH and MeOH/Fe droplets, the flame envelope changes to a spherical form at (↓) and (↑) polarizations at 200, 150 and 100 mm plate spacing. Increasing electric field strength reduced the micro-explosion tendency of Fe particles in the flame region and the micro-explosion intensity of Fe particles was found to be higher in ethanol droplets than in methanol. No systematic relationship could be established between the electric field effect and the presence of Fe particles. The MeOH/Fe/150(↑) droplet exhibited the lowest extinction time of 1050 ms. The electric field fundamentally alters the secondary atomization process of the fuel droplets. Notably, the diameter regression of all MeOH-based fuel droplets deviates significantly from a linear relationship. The investigation into the combustion behavior of pure EtOH, MeOH, and their Fe-blended counterparts within an electric field environment suggests that MeOH and MeOH/Fe fuels exhibit superior combustion characteristics. However, further research is necessary to fully elucidate these findings.

Multiprogrammable Anisotropic Soft Material via Magneto‐Orientation of Ferromagnetic Nanoplates

AbstractAnisotropic materials featured with ordered arrangement of sub‐structures are ubiquitous in living organisms, and possess rapidly increasing relevance to emerging technologies in smart materials, soft robotics, flexible displays, and biomedicines. However, the integration and programming of multiple properties into anisotropic materials, which endow themselves with extended intrinsic capabilities and utilities, still remain a challenge. Herein, we report a multi‐programmable anisotropic material by embedding ferromagnetic two‐dimensional nanoplates into hydrogel matrix. The nanoplate exhibits not only a disc‐like non‐isotropic shape, but also an intrinsic easy magnetization axis perpendicular to its basal plane. Using a directional external magnetic field, we can precisely control the orientation of nanoplates inside hydrogel precursor solution and then fix them via photolithographic polymerization, leading to the fabrication of anisotropic hydrogel with on‐demand ordered alignment of nanoplates. Such deliberate arrangement of nanoplates brings in extraordinary optical properties due to birefringence, enabling us to encrypt pattern information into hydrogel materials that is only visible under polarized light. Soft actuators with programmable optical, mechanical and magnetic properties are engineered, which allow to encode diverse deformation and locomotion modes, determine the actuation sites, and monitor the sub‐structural anisotropy all simultaneously, opening new avenues for the design of anisotropic soft materials.

The hind limb of Octodontidae (Rodentia, Mammalia): Functional implications for substrate preferences

Octodontids are South American caviomorph rodents endemic to mesic and arid biomes displaying a wide range of substrate preferences, from terrestrial to subterranean habits. However, the hind limb morphology of these rodents remain relatively poorly understudied, particularly from an ecomorphological perspective. To investigate the association between hind limb morphology and substrate preference—epigean, semifossorial, fossorial, and subterranean— this study analyzed six skeletal measurements of femur and tibia, along with five morphological indices. We employed phylogenetic mapping, allometry, and multivariate analyses (Phylogentic Flexible Discriminant and Principal Component analyses) on log-transformed variables and indices. The results suggest that the epigeans and subterraneans possess hind limb skeletal features that enhance their mechanical capabilities, which are advantageous for their respective lifestyles. However, in the absence of clear behavioral adaptations or associations, the functional habits of Octodontidae do not requires significant structural modifications of the proximal bones of the hind limbs. These results indicate that understanding the form-function relationship in octodontids requires direct field or laboratory observations of behavior and environmental interactions, highlighting the limitations of current research without such data.

Effect of Direct Current Electric Field on the Clogging Behavior of Submerged Entry Nozzle During Casting of UltraLow‐Carbon Steel

Effect of Direct Current Electric Field on the Clogging Behavior of Submerged Entry Nozzle During Casting of UltraLow‐Carbon Steel

Selection of measurement positions for measuring sound reflection of noise barriers

The number of positions for the in-situ measurement of sound reflection under direct sound field conditions according to EN 1793-5 for road traffic noise reducing devices (NRDs, e.g. noise barriers) depends on the surface structure of the device under test. The surface structure and material homogeneity may be categorized as flat and non-flat as well as homogenous and inhomogeneous. Flat and homogenous NRDs are measured with one central measurement position, whereas non-flat and or inhomogeneous devices require additional measurements points to assess the overall sound reflection properties. In the current version of the standard, NRDs are considered flat, if the depth of their surface structure is below 8.5 cm. Also, they are considered homogenous if the lateral extent of each material is at least 8.5 cm. It is discussed to reduce this criterion from 8.5 cm to 1.7 cm, as research showed significant differences on devices considered as flat between measurement positions for the sound reflection index. An extensive analysis of sound reflection measurements shows the influence of the measurement position for noise barriers with structural depths below 8.5 cm. A new strategy for selecting measurement positions is proposed, which also considers the period length of the surface structure.

Detecting and Imaging of Magnons at Nanoscale with van der Waals Quantum Sensor

AbstractMagnonic devices are extensively studied for energy‐efficient information processing. High spatial resolution and high accuracy measurement is required to characterize the excitation and distribution of magnons. Here, sensing and imaging of magnons in the magnetic insulator (YIG) is realized with negatively charged boron vacancy () spin defects in 2D hexagonal boron nitride (hBN). Thermal magnon noise is studied through spin relaxometry, illustrating the nanometers proximity of the 2D quantum sensor over a large area. The small probe‐sample standoff distance helps to detect weak signals with diffraction‐limited spatial resolution. The uniform out‐of‐plane symmetry axis of is further utilized to study perpendicular magnetic anisotropy (PMA). It effectively extracts the stray field of microwave‐excited magnons from the direct stripline field. The distributions of propagating and localized magnons in different structures are subsequently imaged and analyzed. The work provides the strategy for utilizing the distinctive advantages of the van der Waals quantum sensor in magnetic imaging. The results will promote the development of magnonic devices for diverse applications.

Investigation of the sound insulation and natural ventilation performance of a metamaterial-based open window

Recent advancements in metamaterials have created new opportunities to enhance indoor environmental quality (IEQ) by integrating natural ventilation and sound insulation in architectural designs. Metamaterial-based windows can facilitate natural ventilation, contributing to energy savings while also protecting against outdoor noise. However, international standards for assessing façade sound insulation typically assume all partitions are closed, with only the Danish standard DS 447:2021 accounting for partially open conventional windows. These standards do not address simultaneous noise mitigation and natural ventilation. To fill this gap, this study evaluated a prototype metamaterial-based device called the Acoustic Metawindow (AMW) unit using three experimental methods. These methods included the diffuse field method (ISO 10140 series), an adapted directive sound field method (EN 1793-6), and beamforming to control sound leakages from the AMW unit in both closed and open states. Additionally, the study used an adapted ISO 9972 method to assess the ventilation potential alongside sound insulation of the open AMW unit. The findings revealed that the AMW unit significantly outperformed equivalently open windows, achieving a sound level difference (Dn,e) improvement of 5–15 dB in the 500–5000 Hz frequency range, resulting in a total Dn,e,w of 30 dB. The study also indicated a correlation between the frequency range of effective sound insulation and the metamaterial design features of the AMW unit. This research suggests the possibility of a more inclusive standard that considers partially open sound-insulating devices as windows in the built environment, combining noise mitigation and energy saving.

Electromechanical properties of different phases in ferroelectric crystals regulated by variously oriented electric fields

Electric fields offer a convenient and tunable way to induce phase transitions for regulating the electromechanical properties of ferroelectrics. However, regulating the electromechanical properties by using electric fields in various directions for different ferroelectric phases has yet to be systematically investigated, especially for lead-free material KNbO3. Based on the nonlinear thermodynamics analysis, the electric field-temperature phase diagrams of KNbO3 single crystals under different electric field directions (E[001], E[011], E[111]) have been constructed, along with the electric-field-induced electromechanical responses. The results show that the phase diagrams are markedly different under different electric field directions. Specifically, the electric field-temperature phase diagram appears as a "line"-shaped phase boundary under E[001], while it appears as a "U"-shaped phase boundary under E[011], and an arrowhead-shaped phase boundary under E[111]. It is also found that there are excellent electromechanical responses near both "U"-shaped and arrowhead-shaped phase boundaries due to the significant alterations in polarization slopes near the phase boundaries, offering an alternative pathway to regulate and enhance the electromechanical properties in ferroelectrics.

Characterization of Discharge Associated With Fiber Particle Aggregation in Oil Streams Under High-Voltage Direct Current Field

Characterization of Discharge Associated With Fiber Particle Aggregation in Oil Streams Under High-Voltage Direct Current Field

The adsorption of p-hydroxybenzoic acid on graphene oxide under different pH and in-situ desorption in direct current electric field

The development and ongoing optimization of measures to reduce and eliminate p-hydroxybenzoic acid (p-HBA) in industrial wastewater are significant due to its potential carcinogenic effect and bio-recalcitrant. Graphene oxide (GO) is an ideal adsorbent for removing aromatic acids and achieving adsorbent recovery and resource conservation. In this study, the adsorption properties of p-HBA onto GO at different pH values and the regeneration mechanism of adsorbent under varying electric field intensities were analyzed using molecular dynamics (MD) simulation. The simulation results demonstrate that GO exhibits preferable adsorption capabilities for p-HBA at low pH, and van der Waals (vdW) interaction plays a leading role. However, the adsorption stability decreases at high pH (particularly pH > 9.3) with most p-HBA desorption from the GO surface. When an electric field of 1.0 V/nm is applied to the acidic system (HGO_HBA_HBA−), the total adsorption interaction energy between GO and p-HBA decreases but remains high (−1836.93 kJ/mol). When a 0.6 V/nm electric field is added to the alkaline system (GO2−_HBA2−), the vdW and electrostatic interaction energies are recorded as −35.34 kJ/mol and 3546.97 kJ/mol. The vdW interaction is weak, and electrostatic repulsion increases, facilitating the desorption of p-HBA from the GO surface. This work aims to share insights into the microscopic removal mechanism of p-HBA on the GO surface under different pH values and provide a theoretical perspective on the regeneration mechanism of GO.