Search Results (152)

Terahertz technology has demonstrated immense potential across a wide range of applications, particularly in the realm of THz photodetection. However, state-of-the-art detectors typically face fundamental trade-offs among sensitivity, response speed, operating temperature, and spectral bandwidth. While previous studies have shown that graphene field-effect transistors (GFETs) exhibit a broadband, room-temperature photoresponse to THz radiation—often attributed to photothermoelectric (PTE) and plasma-wave rectification effects—the similar functional dependence of these mechanisms on the gate voltage has historically made it challenging to disentangle their individual contributions. In this study, we leverage monolayer graphene as the photoactive material to overcome these limitations within a single device architecture. We present a novel THz photodetector driven predominantly by the PTE effect, facilitated by a precisely designed counterclockwise spiral antenna. The demonstrated device achieves exceptional room-temperature sensitivity, featuring a minimum noise equivalent power (NEP) of 80.7 $\mathrm{p}\mathrm{W}/\sqrt{\mathrm{H}\mathrm{z}}$ alongside a rapid response time of less than 11 μs. Furthermore, by systematically analyzing the temporal response dynamics, we unambiguously identify the PTE effect as the dominant operating mechanism. These results provide a robust strategy for the development of high-performance, room-temperature THz optoelectronics, paving the way for advanced practical applications in high-capacity wireless communications and real-time THz imaging. Full article

At the end of its last experimental campaign, in December 2023, the Joint European Torus (JET) became available for testing a compact and lightweight Laser-Induced Breakdown Spectroscopy (LIBS) system to be mounted on its robotic arm. The purpose of the test was the in situ chemical characterization of its internal walls and plasma-facing components (PFCs). Among the areas measured, special attention was devoted to the PFCs of the divertor, as this area is most affected by the re-deposition of material eroded from the first wall and unburned nuclear fuel (deuterium and tritium). In this article, we present the results of the LIBS characterization of a PFC of the High Field Gap Closure (HFGC), highly subjected to these phenomena. The in-depth distribution of several ITER-relevant chemical species is discussed through in-depth and correlation analyses, and the interpretation of the results is explained in terms of erosion and re-deposition of materials from the first wall. The study allowed us to estimate the thickness of the ablated layers by each laser shot, which is on the order of a few tens of nanometers, and to outline a mapping of the thickness of the re-deposited material. Full article

Plasma-facing materials (PFMs) for future fusion reactors require advanced mechanical and thermal properties to withstand the extreme challenges of high heat flux, plasma exposure, and neutron irradiation. Tungsten is one of the most suitable materials for use as a PFM in the divertor region. However, considering the high thermal loading/thermal stress combining plasma exposure and neutron irradiation/embrittlement, one of the major concerns for tungsten in PFMs is its intrinsic brittleness. To avoid cracking and components failure, tungsten toughening has been widely investigated, including the development of tungsten fiber-reinforced tungsten composites (W_f/W) using an extrinsic toughening mechanism, which could provide damage resilience against neutron embrittlement. Recently, a type of aligned long-fiber W_f/W (L-W_f/W) based on a powder metallurgical fabrication process was developed, demonstrating advanced fracture toughness while retaining other application-relevant properties. For L-W_f/W, the relatively easy production process suggests the feasibility and basis of industrialization. This work reports on the initial progress in industrializing L-W_f/W, with a focus on adapting the lab sintering process to a sintering process with industrial partner (Dr. Fritsch Sondermaschinen GmbH) and optimizing the process parameters. To improve the sinterability of tungsten and achieve higher density, various tungsten powders were explored, including commercial W powders, bimodal mixtures of different particle sizes, and granulated W powders. At the dedicated yttria interface, the thickness of yttria coating on the fibers was also optimized to ensure effective separation between the fibers and the matrix. Series of samples were produced with different dimensions up to 100 mm × 100 mm × 4 mm. After optimization, samples with 93% density and desired pseudo-ductility were prepared. Similarly to production in the lab, a major challenge in this work involved balancing the densification of the tungsten matrix with controlling fiber recrystallization and mitigating damage to the yttria interface. Full article

Biocompatible thin films are essential for advancing biomedical devices, as they enhance integration with biological tissues, improve device longevity, and reduce complications. The rapid evolution of both medical needs and materials science has led to a diverse array of deposition techniques, each offering unique advantages and challenges for tailoring surface properties without compromising the bulk characteristics of implants and sensors. While laser-based methods—such as pulsed laser deposition (PLD) and Matrix-Assisted Pulsed Laser Evaporation (MAPLE)—are renowned for their precision, ability to preserve complex material stoichiometry, and suitability for low-temperature processing, the broader landscape includes several other important approaches. Physical Vapor Deposition (PVD) techniques, including magnetron sputtering and pulsed electron deposition, are widely used for their ability to create uniform, adherent coatings with controlled thickness and composition, making them suitable for both hard and soft biomedical substrates. Chemical Vapor Deposition (CVD) and its plasma-enhanced variant (PECVD) offer conformal coatings and excellent control over film chemistry, which is particularly valuable for functional polymer and ceramic films. Other methods, such as sol–gel processing, ion beam deposition, and electrophoretic deposition, provide additional flexibility in terms of coating composition, adhesion, and processing temperature, allowing for the fabrication of films with tailored mechanical, chemical, and biological properties. Despite these advances, the field faces ongoing challenges in optimizing film properties for specific clinical applications, ensuring reproducibility, and scaling up production for widespread use. The necessity of this review lies in its comprehensive comparison of laser-based techniques with alternative deposition methods, providing critical insights into their respective strengths, limitations, and suitability for different biomedical scenarios. By synthesizing recent developments and highlighting current gaps, this review aims to guide researchers and clinicians in selecting the most appropriate thin-film deposition strategies to meet the evolving demands of next-generation biomedical devices. Full article

Heavy metals are widespread environmental contaminants from natural and anthropogenic sources, posing risks to human health and ecosystems. In urban areas, levels are elevated due to industrial activity, traffic emissions, and building materials. Camden, New Jersey, a city with a history of industry and illegal dumping, faces increased risk due to aging sewer and stormwater systems. These systems frequently flood neighborhoods and parks, heightening residents’ exposure to heavy metals. Despite this, few studies have examined metal distribution in Camden, particularly during storm events. This study analyzes stormwater metal concentrations across residential and commercial areas to assess contamination levels, potential sources, and land use associations. Stormwater samples were collected from 33 flooded street locations after four storm events in summer 2023, along with samples from a flooded residential basement during three storms. All were analyzed for total lead, cadmium, and arsenic using inductively coupled plasma–mass spectrometry (ICP-MS, (Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ, USA)). Concentration data were visualized using geographic information system (GIS)-based mapping in relation to land use, socioeconomic, and public health factors. In Camden’s stormwater, lead levels (1–1164 µg L⁻¹) were notably higher than those of cadmium (0.1–3.3 µg L⁻¹) and arsenic (0.2–8.6 µg L⁻¹), which were relatively low. Concentrations varied citywide, with localized hot spots shaped by environmental and socio-economic factors. Principal component analysis indicates lead and cadmium likely originate from shared sources, mainly industries and illegal dumping. Notably, indoor stormwater samples showed higher heavy metal concentrations than outdoor street samples, indicating greater exposure risks in flooded homes. These findings highlight the spatial variability and complex sources of heavy metal contamination in stormwater, underscoring the need for targeted interventions in vulnerable communities. Full article

Neuromorphic computing, an emerging computational paradigm, aims to overcome the bottlenecks of the traditional von Neumann architecture. Two-dimensional materials serve as ideal platforms for constructing artificial synaptic devices, yet existing devices based on these materials face challenges such as insufficient stability. Indium selenide (InSe), a two-dimensional semiconductor with unique properties, demonstrates significant potential in the field of neuromorphic devices, though its application research remains in the initial stage. This study presents an artificial synaptic device based on the InSe/Charge Trapping Layer (CTL)/h-BN heterojunction. By applying oxygen plasma treatment to h-BN to form a controllable charge-trapping layer, efficient regulation of carriers in the InSe channel is achieved. The device successfully emulates fundamental synaptic behaviors including paired-pulse facilitation and long-term potentiation/inhibition, exhibiting excellent reproducibility and stability. Through investigating the influence of electrical pulse parameters on synaptic weights, a structure–activity relationship between device performance and structural parameters is established. Experimental results show that the device features outstanding linearity and symmetry, realizing the simulation of key synaptic behaviors such as dynamic conversion between short-term and long-term plasticity. It possesses a high dynamic range ratio of 7.12 and robust multi-level conductance tuning capability, with stability verified through 64 pulse cycle tests. This research provides experimental evidence for understanding interfacial charge storage mechanisms, paves the way for developing high-performance neuromorphic computing devices, and holds broad application prospects in brain-inspired computing and artificial intelligence hardware. Full article

Microwave-Induced Hydrogen Plasma (MIHP) is introduced as a novel synthesis route for producing high-entropy carbides (HECs), offering an alternative to conventional mechanical alloying and/or sintering techniques. In this study, a representative HEC composition, ${\mathrm{MoNbTaVWC}}_5$, was successfully synthesized using MIHP processing at 200 Torr. The process employs microwave energy to generate hydrogen plasma to facilitate carbothermal reduction of metal oxide precursors. The plasma environment generates abundant reactive atomic hydrogen species, which enhance reaction spontaneity and promote efficient HEC formation. X-ray diffraction confirmed the formation of a single-phase rocksalt-type face-centered cubic structure. Scanning electron microscopy combined with energy-dispersive X-ray spectroscopy confirmed uniform elemental distribution within the synthesized microstructure. Nanoindentation measurements yielded hardness and elastic modulus values consistent with literature reports for similar compositions. X-ray photoelectron spectroscopy confirmed the chemical state of carbon to be primarily bonded with metals as carbides, with only minor oxygen present as metal-oxides. Raman spectroscopy performed over the 750–1900 ${\mathrm{cm}}^{-1}$ range yielded a featureless spectrum with no detectable D or G bands often observed for sp²-hybridized disordered carbon, graphite, or graphene materials. These results validate the structural and chemical purity of the synthesized HECs. This work aims to demonstrate the feasibility and reproducibility of MIHP as a synthesis method for HECs. Full article

Background: The conversion of carbon dioxide (CO₂) into valuable products like carbon monoxide (CO) is an important process facing limitations due to poor energy efficiency. Dielectric barrier discharge (DBD) plasma reactors offer a potential solution through synergistic plasma catalysis, making the selection of an optimal solid packing material a critical design challenge. Methods: This study investigated the impact of four different packing materials—Al₂O₃, ZrO₂, glass beads, and kaolin pellets—on the CO₂ conversion process in a DBD reactor. The materials’ physical and chemical properties (porosity and composition) were analyzed. Experiments were conducted to examine the influence of gas flow rates and bead size on CO₂ and CO concentrations. The study utilized optical emission spectroscopy (OES) and kinetic mathematical modeling to characterize the discharge and the reaction. Results: Higher gas flow rates led to a decrease in CO₂ conversion due to reduced specific energy input. The addition of solid packing significantly improved system efficiency by promoting filamentary and surface discharges, with smaller beads yielding higher conversion rates. Notably, kaolin demonstrated unique performance characteristics, suggested by its increased plasma brightness, likely due to flow-induced turbulence promoting the reaction. Conclusions: Proper material selection and packing design are crucial for efficient CO₂ splitting, concurrently boosting energy efficiency and maintaining high conversion. While Al₂O₃ (corundum) shows high intrinsic activity, kaolin emerges as a highly competitive and advantageous material when associated costs are considered paramount for large-scale applications. Full article

Efficient delivery of exogenous genetic material remains a core challenge in plant biotechnology, holding profound implications for sustainable agricultural and forestry development. Although traditional delivery methods such as Agrobacterium-mediated transformation, gene gun bombardment, and electroporation have been widely applied in plant genetic engineering, these systems exhibit limitations including species-dependent efficacy, propensity to cause plant tissue damage, low transformation efficiency, susceptibility to environmental factors. In recent years, with the advancement of nanotechnology, nanoparticle-based nucleic acid delivery systems are emerging as novel tools for applications such as novel tools for dsRNA or transgene delivery. These systems leverage the unique physicochemical properties of nanomaterials, including size-dependent phenomena, tunable surface charge, and enhanced membrane penetration capabilities, to achieve targeted delivery and stable expression of genetic payloads. Nevertheless, nanomaterial-mediated gene delivery systems for plants are still in their nascent stages, and their widespread application faces numerous challenges. This article briefly introduces traditional delivery methods, systematically reviews the applications and progress of nanoparticle-based nucleic acid delivery systems, and discusses the cross-species applicability of nanoparticles, as well as the associated biosafety concerns. We aim to offer insights for tackling the prevailing technical bottlenecks and to provide guidance for the rational design of nanomaterials that efficiently traverse the plant cell wall–plasma membrane barrier and stably deliver nucleic acids without eliciting phytotoxicity. Full article

Tungsten is a prime candidate material for the plasma-facing components of fusion reactors, thanks to its high melting point, high temperature strength, good thermal conductivity, high erosion resistance, etc. Yet, it has some limitations, mainly its brittle nature, difficulty of machining, and propensity to recrystallize at elevated temperatures. Among the approaches to the improvement of particular properties are alloying, dispersion strengthening, thermomechanical processing, and modifications to the sintering process. This study explores the possibility of combining fine powder size with ultra-high pressure to achieve significant densification at moderate temperatures during hot pressing. Two powder sizes and a range of temperatures from 1000 to 2000 °C were used, and their effects were observed. The resulting tungsten compacts were characterized for their microstructure, density, and mechanical and thermal properties. The high pressure enabled substantial densification already at relatively low temperatures, thanks to the plastic deformation of the powder particles. A significant degree of sintering, as manifested by the microstructural and property evolution, occurred however only at higher temperatures. The compacts exhibited brittleness, calling for further optimization of the method. Full article

Aiming at the drawbacks of the classic CoCrFeNi high-entropy alloy (HEA)—low room-temperature strength and softening above 600 °C, which fail to meet strict material requirements in high-end fields like aerospace—this study used the vacuum hot-pressing sintering process to prepare CoCrFeNiTa_x HEAs (x = 0, 0.5, 1.0, 1.5, 2.0 atom, designated as H4, Ta_0.5, Ta_1.0, Ta_1.5, Ta_2.0, respectively). This process effectively inhibits Ta segregation (a key issue in casting) and facilitates the presence uniform microstructures with relative density ≥ 96%, while this study systematically investigates a broader Ta content range (x = 0–2.0 atom) to quantify phase–property evolution, differing from prior works focusing on limited Ta content or casting/spark plasma sintering (SPS). Via X-ray diffraction (XRD), scanning electron microscopy–energy-dispersive spectroscopy (SEM-EDS), microhardness testing, and room-temperature compression experiments, Ta’s regulatory effect on the alloy’s microstructure and mechanical properties was systematically explored. Results show all alloys have a relative density ≥ 96%, verifying the preparation process’s effectiveness. H4 exhibits a single face-centered cubic (FCC) phase. Ta addition transforms it into a “FCC + hexagonal close-packed (HCP) Laves phase” dual-phase system. Mechanically, the alloy’s inner hardness (reflecting the intrinsic property of the material) increases from 280 HV to 1080 HV, the yield strength from 760 MPa to 1750 MPa, and maximum fracture strength reaches 2280 MPa, while plasticity drops to 12%. Its strengthening mainly comes from the combined action of Ta’s solid-solution strengthening (via lattice distortion hindering dislocation motion) and the Laves phase’s second-phase strengthening (further inhibiting dislocation slip). Full article

This study employed atmospheric plasma spraying (APS) technology to successfully fabricate CoCrFeNiMo high-entropy alloy (HEA) coatings under varying spraying currents and systematically investigated the effects of the spraying current on the microstructure, mechanical properties, and tribological behavior of the coatings. Results showed that the material composition remained consistent across different current levels, primarily consisting of face-centered cubic (FCC) solid solution phases, FeCr₂O₄ spinel phases, and Cr-rich FCC1 phases. The FCC matrix was dispersed with spherical Cr oxide particles smaller than 30 nm in diameter, which significantly enhanced the strength of the coatings. As spraying current increased, both porosity and microhardness exhibited a non-monotonic trend—initial optimization followed by deterioration. At 500 A spraying current, the coating achieved optimal performance, with the lowest porosity (0.42%) and highest microhardness (569.8 HV). Correspondingly, this condition also yielded the best wear resistance, with stable friction coefficients and wear rates reaching 0.49 and 6.91 × 10⁻⁵ mm³/N m, respectively. Abrasion surface analysis revealed that excessively low or high currents triggered distinct wear mechanisms leading to reduced wear resistance. Full article

Chronic cold stress is a severe test that animals in cold regions have to face during winter. However, the lack of precise dietary adjustments for animals in cold regions represents a significant gap in addressing their nutritional needs. Full-fat rice bran is one of the feed materials rich in protein, lipids, dietary fiber, and antioxidant-active substances. Glucose is the most common quick energy supply. We determined dietary full-fat rice bran and glucose can improve the growth and health of cold-exposed pigs. A total of 18 Yorkshire pigs were randomized to one of three treatment groups (basal diet, full-fat rice bran diet (20%), and glucose diet (10%)) for 22 d to evaluate the effects of full-fat rice bran and glucose on growth performance, antioxidants, microbiomes, and bile acid circulation in cold-exposed pigs. The results showed that dietary full-fat rice bran decreased the average daily feed intake (p < 0.05), increased superoxide dismutase (SOD) activity in plasma (p < 0.05), and decreased Rikenellaceae_RC9_gut_group and Campylobacter in the colon microbiota of cold-exposed pigs (p < 0.05). Dietary glucose improved the growth performance of cold-exposed pigs and decreased the abundance of Prevotellaceae_NK3B31_group (p < 0.05) in the colon microbiota of cold-exposed pigs. Dietary full-fat rice bran and glucose both downregulated the abundance of Alloprevotella, Bradymonadales, and Erysipelotrichaceae in colon microbiota (p < 0.05), promoted the production of SCFAs, and activated the FXR-CYP7A1 signaling pathway. Dietary full-fat rice bran or glucose promoted fecal excretion of bile acids. This study demonstrated that dietary supplementation with full-fat rice bran or glucose can improve the colonic microbiota structure and SCFA levels in cold-exposed pigs. When comparing the two dietary strategies, the glucose-supplemented diet is more beneficial to the growth performance of cold-exposed pigs, while the full-fat-rice-bran-supplemented diet is more conducive to enhancing the function of their antioxidant system. Additionally, dietary supplementation with full-fat rice bran or glucose can also regulate the bile acid circulation in pigs, thereby enhancing their cold adaptation ability. Full article

Tungsten (W) is regarded as the most promising plasma-facing material in thermonuclear fusion reactors due to its excellent properties, such as high strength, a high melting point, and a low sputtering rate. However, its low-temperature brittleness, recrystallization embrittlement, and irradiation embrittlement seriously limit the practical application of W. In this research, the properties of tungsten-based materials were improved by introducing second phases into W. Core–shell composite powders with W particles as core and Sm(OH)₃ thin films as shell were prepared by electroless plating, and sintered by spark plasma sintering (SPS) to obtain bulk. After sintering, the Sm(OH)₃ shell transformed into the Sm₂O₃ phase with a different size, mainly distributed at W grain boundaries. The average size of W grains in the composite material was smaller than that of pure W sintered bulk due to the pinning of W grain boundaries by Sm₂O₃, while the porosity of the composite is reduced. Compared with pure W sintered bulk, the composites exhibited better mechanical properties and radiation resistance; although the thermal conductivity decreased somewhat, it still maintained a high level. With the increase in sintering temperature and pressure, the evolution of core–shell powders during the sintering process could be simplified into six stages, which occurred approximately in sequence. Full article

Plasma-facing components (PFCs) are among the most critical functional components in a nuclear fusion device. Their reliability and durability under high heat loads are directly tied to the safe operation and lifetime of the fusion device. Under cyclic high thermal loads, accumulated plastic strain can lead to material property degradation. Furthermore, severe temperature gradients generate alternating tensile and compressive stresses within the material, resulting in the initiation and propagation of microcracks, ultimately causing structural failure of the PFCs. This study focuses on the issues of thermal stress concentration and plastic strain accumulation at the tungsten (W)/copper (Cu) joint interface and proposes an optimized design scheme based on a laminated tungsten structure. Using a combined approach of finite element simulation and theoretical analysis, the effects of tungsten layer thickness and interface geometry on the thermomechanical performance of the PFC joint were systematically investigated. The results indicate that reducing the thickness of tungsten sheet can significantly decrease the interfacial stress level. As the tungsten sheet thickness is reduced from the millimeter scale to the micrometer scale, the thermal mismatch at the W/Cu interface is reduced, thereby leading to a notable reduction in normal stress along the axial direction. In particular, when the thickness falls below 10 μm, the axial normal stress approaches zero, and the equivalent stress at the interface is effectively mitigated. Further research indicates that optimizing the flat W/Cu interface into an arc-shaped interface can alter the location of stress concentration. When the ascending distance of the Cu exceeds 600 μm, the stress concentration at the interface vertex is essentially eliminated. However, an excessively ascending distance of the Cu can exacerbate plastic deformation in the copper layer. By optimizing the extended distance of the Cu, a balance between stress relief and plastic strain accumulation can be effectively achieved. Full article