Nanotechnology最新文献

The rapid rise of antibiotic resistance threatens global health, highlighting the need for new antimicrobial strategies. Here, we investigated nitrogen vacancies and Ag nanoparticles decoration in carbon nitride (Ag-g-C₃N₄-V). Nitrogen vacancies optimized the electronic structure, boosting light absorption and charge separation. Ag nanoparticles induced a synergistic effect via localized surface plasmon resonance and the conjugated C₃N₄network, enhancing visible-light photocatalysis. The composite promoted hydrogen peroxide (H₂O₂) generation, a reactive oxygen species with antibacterial activity. The incorporation of Ag synergistically coupled H₂O₂generation with Ag⁺release, leading to enhanced bactericidal performance. Treatment with Ag-g-C₃N₄-V reduces the survival rates ofE. coliandS. aureusby approximately 39% and 58% respectively compared to the control group; under light conditions, Ag-g-C₃N₄-V lowers the survival rates ofE. coliandS. aureusto only 16% and 6%, showing a more remarkable bactericidal effect. This work offers a strategy for designing multifunctional photocatalysts against bacterial infections with potential biomedical applications.

Electric conduction mechanisms in pressed powder samples consisting of molybdenum-disulfide-oxide (MoS_xO_y) nanoflakes depending on their content and structure have been investigated. The MoS_xO_ynanoflakes were synthesized in the temperature range of 130 °C-180 °C by reaction of (NH₄)₆Mo₇O₂₄with thiourea in aqueous solution followed by aerial oxidation. The chemical composition and structure of the powders have been determined by means of XPS, EDS and Raman spectroscopy. The obtained nanoflakes are 10-20 nm thick and self-assembled into 'nanoflower'-shaped agglomerates forming powder particles. The agglomerates in powders synthesized at different temperatures are shown to consist of MoS₂and molybdenum oxides/sulfoxides whose content ratios differ from each other in powders depending on their synthesis temperature. The current versus voltage (I-V) dependences of the pressed powder films manifest a hysteresis-like behavior with substantial dependence on this ratio. For the samples with the highest content of the Mo oxide/sulfoxide nanoflake forms (⩾50%) one observes the negative differential conductivity (NDC) in theI-Vcharacteristics and a very large difference between the forward and backwardI-Vbranches at small DC biases. However, the samples with low content of these forms have slightly non-linearI-Vcharacteristics, narrower hysteresis loops and the absence of NDC. All samples manifest a long-lasting (tens of seconds) transient charge/discharge process after switching 'on/off' the voltage across the sample and ability of large charge accumulation, with the specific capacitance equal to achieving 12 ÷ 75 F g^-1depending on the powder synthesis temperature. These phenomena provide evidence of the important role of interface charges in the MoS_xO_ypowder electric conduction mechanisms. To describe theoretically the observedI-Vcurves, polar and electric-transport properties of the pressed MoS_xO_ynanoflake films, the Landau-Cahn-Hilliard approach considering flexo-chemical field has been used. The revealed features of electric conduction and charge accumulation look interesting for possible applications in nanoelectronics and charge storage devices.

Altermagnetic materials are a new type of magnetic materials that have recently garnered significant attention due to their exceptional properties, while the Rashba-Edelstein effect (REE) serves as a crucial charge-to-spin conversion mechanism. In this study, we explore the commonalities in symmetry dependence between altermagnetic materials and the occurrence of the REE. Utilizing a self-developed program for quantifying the REE, we calculate the REE intensity of altermagnetic materials after breaking symmetry constraints via twisting. By comparing the REE intensities between altermagnetic materials with weak spin-orbit coupling (SOC) and transition metal dichalcogenides with strong-SOC following symmetry breaking through twisting, it is found that efficient REE can be achieved in weak-SOC altermagnetic materials through symmetry regulation. This result breaks the traditional reliance of the REE on strong-SOC materials, providing theoretical support for the material design and functional optimization of next generation spintronic devices.

Tellurium (Te), a typical p-type elemental semiconductor, exhibits exceptional properties including environmental stability, high carrier mobility, and superior optical responsiveness, demonstrating significant application potential in next-generation optoelectronic devices. This review provides a systematic overview of the crystal structures and optoelectronic properties of Te, along with the research progress in the field of Te-based photodetectors. Firstly, the crystal structures and band characteristics of Te are elucidated, with its optical and electrical properties analyzed in depth to lay a theoretical foundation for subsequent research. On this basis, the photoelectric performance and operating mechanisms of photodetectors based on individual Te nanomaterials are explored, encompassing one-dimensional Te nanowires, nanoribbons, nanocoils, and two-dimensional Te nanosheets and nanofilms. Furthermore, the structural designs and application potential of Te nanomaterial heterostructure photodetectors based on different band alignment types are elaborated in detail. Finally, the current bottlenecks encountered by Te-based materials in the field of photoelectric detection are synthesized, and perspectives on future research directions within this field are delineated. We believe that that frontier explorations of Te-based materials will yield significant breakthroughs, and such research will offer highly valuable industrial references for the commercialization of nanodevices.

Employing amorphous superconductors, such as type-II molybdenum silicide (MoSi), instead of crystalline materials significantly simplifies the material deposition and scalable nanoscale prototyping, beneficial for quantum electronic and photonic device fabrication. In this work, deposition of amorphous superconductive MoSi thin films on flat and nanowire (NW) substrates was demonstrated via pulsed direct-current magnetron co-sputtering from molybdenum and silicon targets in an argon atmosphere. MoSi films were deposited on oxidized silicon wafers and Ga₂O₃NWs with 6 nm Al₂O₃insulating shell, grown around the NWs using atomic layer deposition, and studied using scanning and transmission electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy. Four-point Cr/Au electrical contacts were defined on the thin films and on individual Ga₂O₃-Al₂O₃-MoSi core-shell NWs using lithography for low-temperature electrical measurements. By controlling the sputtering power of the targets and thus adjusting the molybdenum-to-silicon ratio in the MoSi films, their properties were optimized to achieve critical temperatureT_cof 7.25 K. Such superconducting shell NWs could provide new avenues for fundamental studies and interfacing with other materials for quantum device applications.

Bulk Mn₄Si₇is a metallic ferromagnet with a weak magnetic momentµ= 0.012µ_B/Mn below its Curie temperatureT_C∼40 K. Here we report results from magnetic and electron spin resonance (ESR) studies in two samples of nanoparticles (NPs) of Mn₄Si₇prepared by high-energy ball milling for 40 h (B40) and 50 h (B50). Williamson-Hall analysis of the linewidths of various x-ray diffraction (XRD) lines of the two samples yielded average particle diameter <D>= 123 nm with strainη= 1.45 × 10^-2for B40 and <D>= 43 nm withη= 1.22 × 10^-2for B50. Using transmission electron microscopy, a near symmetrical log-normal distribution of particle sizes was found for B40 with <D>= 95 nm whereas for B50, <D>= 10.7 nm was found with the distribution highly skewed towards larger sizes. The larger 〈D〉 from XRD is explained on the basis of this size distribution. Both samples show hysteresis loops in the magnetizationMvsHdata at 340 K as well as at 3 K with coercivityH_C∼ 1 kOe (0.5 kOe) for B50 (B40) at 3 K. TheMvsTvariations for the field-cooled (FC) and zero-field-cooled (ZFC) cases withH= 500 Oe along with that of ΔM=M(FC)-M(ZFC) shows blocking temperatureT_B∼ 30 K with ΔMbeing positive at 300 K for both samples signifyingT_C> 300 K. ESR spectroscopy at 300 K yielded spectra characteristic of Mn²⁺ions with zero field splitting and effective spinS= 5/2 andg∼ 2.0. It is argued that the observed room temperature ferromagnetism is due to these strain-stabilized Mn²⁺ions present on the surface of the NPs in the reduced coordination environment of atoms on the surface of NP. The enhanced magnetization and ESR in the smaller B50 NP vis-a-vis larger B40 NP supports this conclusion.

Silicon nanowire (SiNW) arrays present a promising platform for high-performance hydrovoltaic devices (HDs). However, charge extraction from the SiNW tips remains a key challenge. This work introduces a silver wire (AgW) network as a conjoint top electrode to enable high-efficiency charge collection. Thein-situassembled AgWs form a conformal conductive network that bridges numerous SiNW tips in parrel, effectively interconnecting independent SiNW hydrovoltaic microunits and facilitating efficient charge transport to grid electrodes. Systematic optimization reveals that an AgW areal density of 0.050 mg cm^-2leads to a significant performance boost of SiNW HDs, achieving a 101% increase in output power density compared to reference devices. Furthermore, the AgW conjoint top electrode exhibits good stability under hydrodynamic flushing (13.5 m min^-1), with only an initial 12% performance decay due to the removal of loosely bound nanowires, followed by consistent output over repeated flushing cycles. This work demonstrates a simple yet effective strategy for enhancing charge collection in SiNW HDs, offering a practical pathway toward new-type silicon-based energy harvesting systems.

This study investigates the damage mechanisms induced by HPM stress in GaN HEMTs using Sentaurus TCAD numerical simulations and proposes corresponding multi-scale protection strategies. A comprehensive simulation model of a depletion-mode GaN HEMT was established. The analysis of the evolution of internal electric field, current density, and temperature profiles under HPM stress reveals that the failure mechanism is primarily attributed to an electro-thermal positive feedback loop between the gate and source, leading to thermal accumulation and eventual thermal breakdown when the lattice temperature reaches the melting point of GaN. Based on this understanding, protection strategies were developed through structural optimization. The results demonstrate that moderately increasing the gate length (0.25-0.3μm), extending the field plate length (1.85-2.25μm), and optimizing the channel layer thickness (0.4-0.6μm) effectively reduce the internal electric field and current density, thereby mitigating thermal accumulation and enhancing HPM resilience without significantly compromising DC performance.

Memristors are promising candidates for artificial synapses in neuromorphic computing systems, yet their performance is often limited by nonlinear conductance modulation in oxide-based memristors. This work systematically investigates the modulation mechanism governing conductive filament (CF) rupture behavior utilizing distributed barrier layers based on finite element simulations. Our initial electro-thermal simulations of a HfO₂-based memristor with a single-layer Al₂O₃barrier (SLB) thickness (h= 0, 3, 6, 12 nm) showed only limited improvement in synaptic linearity. In contrast, the introduction of a (HfO₂/Al₂O₃)_nmultilayer barrier (MLB) structure fundamentally alters the switching dynamics. Simulations reveal that appropriately increasing the number of layers (n) promotes a transition from continuous to spatially discrete oxygen vacancy migration pathways. This engineered disorder expands the CF rupture region from a localized position to multiple interfaces, thereby reducing the electric field and temperature peaks and driving the set and reset process from abrupt to gradual switching. The optimized MLB device (n= 4) exhibits significantly enhanced synaptic linearity and analog switching characteristics, closely emulating biological synapse behavior. Furthermore, system-level validation using this device model achieved an accuracy of 94.34% in handwritten digit recognition. This work elucidates the physical mechanism by which MLBs enhance conductance linearity, providing a novel design strategy for high-performance memristive synapses.

Immunosuppression within the tumor microenvironment (TME) is a major factor driving pancreatic cancer progression and therapeutic resistance. To address this challenge, we developed a nano-codelivery system, CGT (Cilengitide)-Cls-PTX (paclitaxel)/CM (cell membrane), for the co-delivery of PTX and tumor cell lysate-derived antigens from pancreatic cancer cells (from human pancreatic cancer PANC-1 and mouse pancreatic cancer PANC02 cells). The system was constructed by synthesizing an integrinαvβ3-targeting lipid, DSPE-PEG₂₀₀₀-CGT, and fusing PTX-loaded liposomes with pancreatic cancer cell membranes. This strategy enables preferential accumulation in the TME, where tumor antigens are released to stimulate dendritic cell (DC) maturation and relieve TME immunosuppression, thereby achieving synergistic antitumor efficacy via PTX-mediated tumor cell killing and antigen-induced immune activation. Physicochemical characterization by¹H-nuclear magnetic resonance, transmission electron microscopy, and Western blot confirmed successful synthesis and membrane fusion. Immunostimulatory activity was evaluated using ELISA, flow cytometry, and co-culture assays, and therapeutic efficacy was assessed in a PANC02 murine pancreatic cancer model with Cls-PTX as the control. CGT-Cls-PTX/CM significantly enhanced DC maturation, upregulated co-stimulatory molecules (CD80, CD86), and promoted secretion of interleukin-6 (IL-6) and interleukin-12 (IL-12). Furthermore, it increased CD4⁺and CD8⁺T-cell proliferation, elevated interferon-γ(IFN-γ) production, suppressed transforming growth factor-β, and facilitated cytotoxic T lymphocyte infiltration into tumor tissues. Overall, CGT-Cls-PTX/CM effectively remodels the immunosuppressive TME, achieving synergistic antitumor effects through combined chemotherapy and immune modulation. This strategy offers a promising approach for enhancing immunotherapeutic efficacy against pancreatic ductal adenocarcinoma, a prototypical 'cold' tumor resistant to immune checkpoint therapy.