Search Results (228)

The ultra-wide bandgap semiconductor β-Ga₂O₃ is a promising material for next-generation optoelectronic systems and hybrid nanodevices. However, high interface state densities and anomalous trap-assisted leakage severely restrict its performance and signal transduction capabilities. To resolve these fundamental limitations, we investigated a two-dimensional h-BN interlayer to construct a high-quality heterogeneous metal/h-BN/β-Ga₂O₃ structure using experimentally calibrated Sentaurus TCAD simulations. Energy-band analysis and validated I–V simulations reveal that the low-dimensional h-BN interlayer reconstructs the interfacial barrier, suppresses interface-assisted recombination, and shifts the dominant carrier transport from thermionic emission to Fowler–Nordheim tunneling. These effects markedly reduce the interface-state density and effectively suppress the Shockley–Read–Hall recombination current, mechanisms that are critical for minimizing dark current and improving device sensitivity. After systematically examining the effects of key parameters on the electrical characteristics of this hybrid architecture, we quantify the tradeoff between threshold voltage and on-resistance using a comprehensive figure of merit. Specifically, our results indicate that maximum device efficiency is achieved only when an optimal h-BN thickness of 3.56–5.88 nm (10–17 atomic layers) is strategically integrated with the appropriate metal work function and semiconductor doping. Overall, this work suggests the potential advantage of 2D h-BN in mitigating the interfacial bottleneck of traditional β-Ga₂O₃ platforms, providing quantitative design guidelines and theoretical support for the heterogeneous integration of next-generation optoelectronic devices. Full article

The phytopathogenic bacterium Pectobacterium carotovorum (Pcc) infects a wide range of crop plants and causes substantial economic losses. The authors of this study previously demonstrated that the selenium–arabinogalactan nanocomposite (Se/AG NC) is capable of mitigating the negative effects of infection of soybean seeds with Pcc during germination and can influence physiological and biochemical factors in the seedlings. This study investigated changes in the membrane fatty acid (FA) profile of soybean seedlings grown under different treatments and in control using chromatography–mass spectrometry (CMS). The soybean seed treatments included the following: (1) infection by Pcc alone; (2) nanopriming with Se/AG NC alone; and (3) infection by Pcc followed by nanopriming with Se/AG NC. The infection was performed by soaking seeds in a bacterial suspension. Nanopriming was performed by placing the seeds in an aqueous solution of Se/AG NC (6.25 µg/mL) with a Se concentration of 0.000625%. Then, the seeds were germinated over 5 days in the darkness at 25 °C. The FA profile of soybean seeds was characterized by 13 FAs dominated by linoleic (LA), linolenic (LNA), oleic (OA), palmitic (PA) and stearic (SA) acids. Se/AG NC nanopriming had no influence on the FA profile of soybean seeds. A unique FA profile of soybean seedlings was demonstrated. It consisted of 18 FAs containing 12 to 20 carbon atoms. The following FAs were dominant in the control samples: PA (28%), LA (32.8%), LNA (18.6%), and SA (7.5%). Pcc infection of the seeds amplified the content of unsaturated FAs. Nanopriming of the seeds with Se/AG NC had an obvious influence on the seedling FA profile. Treatment of soybean seeds infected with Pcc using Se/AG NC caused weakening of the detrimental effects of the pathogen, while giving the possibility to maintain soybean seedlings’ FA profile at the control level. Transcript levels of the GmFAD8-2 gene encoding the membrane-bound omega-3 FA desaturase (FAD) were elevated for soybean seedlings after both Pcc and Se/AG NC seed treatment processes. The FA double-bond index (DBI) grew under the influence of seed infection and dropped under other treatments. Nanopriming of the seeds with Se/AG NC effectively reduced stress in Pcc-infected plants, as evidenced by analysis of the abscisic acid (ABA) content. Variations in the membrane FA composition under nanopriming with Se/AG NC may be one of the forms of its phytoprotective effect. Full article

The quantum Zeno and anti-Zeno effects describe how frequent measurements can either suppress or accelerate quantum dynamics. While extensively studied in various platforms, their manifestation in dark-state dynamics remains largely unexplored. Here we investigate the stability of dark states in a cavity quantum electrodynamics (QED) system consisting of two atoms coupled to a single-mode cavity, subject to thermal dephasing that models continuous quantum non-demolition monitoring. Using the Tavis–Cummings model within a Lindblad master equation framework, we perform numerical simulations to investigate how measurement-induced dephasing affects dark-state retention and stabilization time. Through systematic numerical scans, we identify distinct parameter regimes corresponding to Zeno and anti-Zeno behavior: at low dephasing intensities, increasing the measurement strength accelerates the loss of dark-state coherence (anti-Zeno regime), while at higher intensities, it slows down the dynamics and partially recovers dark-state weight (Zeno regime). The transition between these regimes is controlled by the dephasing rates, the cavity photon exchange, and the asymmetry in atom–field couplings. We show that even under strong dephasing, a finite dark-state component persists, demonstrating remarkable robustness. Our results provide insights into the interplay between measurement back-action and decoherence in open quantum systems, with implications for quantum control and information storage. Full article

Hydrogen (H₂) is a promising clean energy carrier with the potential to partially replace fossil fuels. Biological H₂ production using microorganisms offers an environmentally friendly alternative. The halotolerant cyanobacterium Aphanothece halophytica can produce H₂ under nitrogen-deprived and dark anaerobic conditions. In this study, a co-culture strategy was investigated to enhance H₂ production. Five bacterial strains were screened for their ability to improve H₂ production when co-cultivated with A. halophytica. Among them, Staphylococcus aureus significantly enhanced H₂ production, achieving a maximum rate of 11.11 ± 0.18 µmol H₂ g⁻¹ dry weight h⁻¹. Optimization of the bacterial partner revealed that S. aureus cells harvested at 12 h in the mid-logarithmic phase with an OD₆₀₀ of 4.0 were the most effective. An inoculum ratio of A. halophytica to S. aureus of 4:1 further enhanced H₂ production, increased bidirectional hydrogenase activity, and reduced O₂ accumulation. Under optimal conditions (0.945 mmol C-atom L⁻¹ glucose, 0.25 M NaCl, pH 7.4, and 35 °C), the maximum H₂ production rate reached 132.49 ± 4.45 µmol H₂ g⁻¹ dry weight h⁻¹, approximately 5.5-fold higher than that under normal conditions. The co-culture achieved a cumulative H₂ yield of 3248.51 ± 88.11 µmol H₂ g⁻¹ dry weight after 48 h. Full article

This paper extensively explores the concept of dark atoms, hypothetical stable lepton-like particles with a charge of $-2n$ (where n is any natural number) that form neutral bound states with n primordial helium nuclei. The discussion begins with the introduction of multiply charged stable particles. Next, the formation and evolution of dark atoms are examined, followed by a review of related constraints. The capture of dark atoms by the Earth and implications for direct dark matter search are subsequently discussed. Then, the quantum-mechanical description of bound states between dark atoms and ordinary nuclei is addressed. Moreover, procedures for systematic comparisons with this model, which have general interest, are presented considering the DAMA published results on the dark matter annual and diurnal modulation signatures as a benchmark. Full article

Dark current represents a fundamental limiting factor in photodiode performance, establishing the noise floor and constraining detectivity in low-light applications. This comprehensive literature review examines publications covering the physical mechanisms underlying dark current generation and diverse techniques employed for its reduction. Covered mechanisms include diffusion current, Shockley–Read–Hall (SRH) generation–recombination, trap-assisted tunneling, band-to-band tunneling, and surface leakage, each examined with respect to its physical origin and characteristic signatures. Reduction strategies are categorized into thermal management approaches, surface passivation techniques including atomic-layer-deposited aluminum oxide (ALD Al₂O₃), guard ring architectures (attached, floating, and combined configurations), gettering and defect engineering methods, doping profile optimization, bias voltage management, and advanced device architectures such as pinned photodiodes and black silicon structures. A classification table organizes all the reviewed literature by material system, reduction technique, and key findings. Special emphasis is placed on silicon, germanium, III–V compounds, and emerging material photodiodes relevant to near-infrared detection, CMOS imaging, single-photon avalanche diodes (SPADs), and Time-of-Flight (ToF) applications. Full article

The main commercial species of coffee is Coffea arabica; however, it is highly susceptible to biotic and abiotic factors. For this reason, scions of Coffea arabica species are used on robusta (Coffea canephora) rootstocks since grafting can modify the organoleptic, nutraceutical, and nutritional characteristics of crops. The objective of this study was to evaluate the effects of five roasting degrees (light, medium light, medium, medium dark, and dark) in two varieties of Coffea arabica species (Colombia Rojo and Costa Rica 95) and their respective grafts on C. canephora variety Romex. The concentrations of acrylamide, caffeine, and chlorogenic acids were analyzed using HPLC, and the nutrient content was analyzed using plasma induction atomic emission spectrophotometry. The graft of the Colombia Rojo variety with the medium dark roast had the highest concentration of caffeine (1.523%). The same variety with the light roast had the highest concentration of chlorogenic acid (3.088 mg g⁻¹), while the highest acrylamide content (336.70 ng g⁻¹) was found in the same variety with the medium light roast. The roasting degree, variety, and grafting of coffee influence the organoleptic, nutraceutical, and nutritional contents of coffee infusions. Full article

The influence of pre-deformation on the microstructure and mechanical properties of a Mg-rich high-Cu Al-Mg-Si-Cu alloy was systematically investigated by hardness measurement, tensile test, and atomic resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). With the increase in pre-deformation strain (0–10%), the hardness and strength of the alloy after PB hardening increased progressively, accompanied by a continuous reduction in tensile elongation. Notably, increasing pre-deformation strain from 2% to 10% did not bring a significant enhancement in bake hardening response, despite the gradual improvement in the strain hardening capability of the alloy. An optimal pre-deformation strain of 5% is identified, which enabled the alloy to achieve a superior and industrially feasible combination of strength and ductility, balancing practical forming demand (T4 temper) and service performance (PB state). Pre-deformation can significantly affect the morphology and atomic structure of precipitates for the alloy. Dislocations introduced by pre-deformation acted as heterogeneous nucleation sites, inducing the formation of elongated and string-like precipitates along dislocation lines. A distinct Cu segregation behavior was observed in the pre-deformed alloy with the majority of Cu atoms segregated at the precipitate/α-Al interface, which was in sharp contrast to their dominant distribution within the precipitate interior in the non-pre-deformed alloy. These findings provide new insights into deformation-assisted precipitation regulation in Mg-rich high-Cu Al-Mg-Si-Cu alloys and offer practical guidance for optimizing the strength–ductility synergy of such alloys for automotive lightweight manufacturing applications. Full article

Two-dimensional (2D) materials are competitive in a diverse range of areas, spanning from electronic and optoelectronic devices to wearable devices, due to their unique physical and chemical characteristics, as well as remarkable flexibility. As a typical 2D material, lead iodide (PbI₂), featuring a high atomic number and tunable band gap, has been extensively studied in many applications of electroluminescent (EL) devices, photodetectors, and perovskite solar cells. However, high-performance PbI₂-based photodetectors remain a challenge. Herein, we present a high-performance flexible photodetector based on 2D layered PbI₂ nanoplates, which were synthesized via a straightforward air sublimation method. The PbI₂-based photodetector exhibits an excellent photoresponse and the highest responsivity peaks at 34 A/W at 405 nm, together with an ultrahigh transient switching on/off current ratio of 10⁷. Due to a low dark current (10⁻¹⁴ A), the device exhibits an extremely low noise level (<10⁻²⁶ A²Hz⁻¹) and acceptable detectivity (2 × 10¹⁰ Jones). Furthermore, remarkable mechanical flexibility was observed in the device on a PET substrate, preserving both its electrical conductance and photoresponse stability after 560 bending cycles. Finally, high-resolution imaging applications were implemented under a 100 Hz modulated light signal. This work highlights the superior optoelectrical properties of 2D PbI₂ growth by the in-air sublimation method and proves its promising future in flexible and wearable optoelectronic devices. Full article

Catalytic ozonation often suffers from a low ozone utilization rate and incomplete mineralization of organic pollutants. To address these challenges, we designed and prepared a novel catalyst via a one-step thermal polymerization method, anchoring single-atom manganese on a glucose-derived carbon network-modified C₃N₅ framework (Mn/C-C₃N₅). Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC-HAADF-STEM) on an FEI Titan Themis Z microscope confirmed the atomic dispersion of Mn sites, while Raman spectroscopy using a Renishaw inVia Reflex laser micro-Raman spectrometer verified the successful incorporation of a graphitic carbon network within the C₃N₅ matrix. Moreover, electrochemical analyses, including electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) performed on a Bio-Logic SP-150 electrochemical workstation, demonstrated that the integration of the conductive carbon matrix substantially enhanced the interfacial charge transfer capability. The optimized Mn/C-C₃N₅ catalyst demonstrated exceptional performance in phenol mineralization, achieving a 97% total organic carbon (TOC) removal within 60 min, a remarkable improvement compared to pristine C₃N₅ (30%). Furthermore, the catalyst exhibited excellent operational stability, preserving more than 95% of its original activity over five repeated runs. Mechanistic investigations, including electron paramagnetic resonance (EPR) spectroscopy and radical quenching experiments, revealed that the Mn/C-C₃N₅ system accelerated the generation of multiple oxidizing radicals (•O₂⁻, ¹O₂, and •OH), with •OH identified as the predominant reactive species responsible for complete mineralization. This work establishes an integrated catalytic platform and provides fundamental insights into electronic structure modulation for designing advanced oxidation catalysts. Full article

As is known, the standard cosmological model ($\mathsf{\Lambda }$CDM ) demonstrates reasonable agreement with observations of the large-scale structure of the Universe. However, the model shows significant differences between observations of individual galaxies and numerical simulations. To address these discrepancies, various extensions of $\mathsf{\Lambda }$CDM are being explored, one of which is self-interacting dark matter (SIDM). We employ a SIDM model characterized by a dark Coulomb-like interaction between dark electrons and dark protons and mediated by a dark photon. An essential feature of such models is recombination—the formation of ‘dark atoms’, which can be part of dark matter (DM). The spatial distributions of two-component DM that may explain the positron anomaly have been studied in earlier studies. Our contribution is to calculate three-body recombination rates and the resulting neutral fraction of ‘dark atoms’, as well as to show that the recombination process provides a natural mechanism for generating such two-component DM during the evolution of the Universe. Full article

In this study, in situ P-doping of Ge-based layers has been studied and compared with implanted layer profiles acting as absorbent top layer in PIN photodetectors. Several structures containing multilayers of n⁺-Ge/i-Ge, n⁺-GeSi/i-Ge, and n⁺-Ge/i-GeSi, were designed to regulate dopant out-diffusion and interface quality. The purpose of this study is to make an optimized n-type doping layer for PIN photodetectors with low dark current, high responsivity, and high quantum efficiency operating in short wavelength infrared (SWIR) region. The Ge-based structure on Si substrate was transferred to oxidized Si substrate and was finally back-etched from Si to form Ge-on-insulator (GOI) substrate. Comprehensive characterization using high-resolution X-ray diffraction (HR-XRD), secondary ion mass spectrometry (SIMS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and photoluminescence (PL) have been applied at the first stage of our work. The initial Ge layer contains tensile strain of 0.15–0.17%. PL measurements further indicate a redshift of the Γ-LH transition and carrier-concentration-induced quenching at high doping levels, highlighting the competing effects of band filling and non-radiative recombination in heavily n-doped Ge structures. To circumvent this fundamental trade-off, we devised a decoupled device strategy in which the active absorption region employs an intrinsic Ge/GeSi nanoscale multilayer structure to preserve crystal and interface quality. Although, the epitaxial growth parameters were on the optimized conditions, still out-diffusion (in form of segregation and auto-doping) of P could not be impeded. Our final n-type layer in PIN structure was formed by implantation. This approach yields high-performance photodetectors with a peak responsivity of 0.99 A/W at 1550 nm, a corresponding external quantum efficiency of 79%, and low specific contact resistivities of 2.66 × 10⁻⁶ Ω·cm² (n-type) and 1.38 × 10⁻⁸ Ω·cm² (p-type). This work demonstrates that the strategic combination of multilayer/interface engineering and ion-implantation-based doping is a highly effective strategy for tailoring the optoelectronic properties of Ge-based nanomaterials for high-performance SWIR photodetection. Full article

The giant atom paradigm, where a single quantum emitter couples to a continuum at multiple discrete points, has enabled unprecedented control over light-matter interactions, including decoherence-free subspaces and chiral emission. However, realizing these non-local effects beyond the microwave regime remains a significant challenge due to the diffraction limit. Here, we theoretically propose a photonic analog of giant atoms operating at optical frequencies, utilizing a quantum emitter resonantly coupled to a pair of spatially separated single-mode cavities interacting with a common 1D photonic continuum. By rigorously deriving the effective non-Hermitian Hamiltonian and integrating out the bath degrees of freedom, we demonstrate that the interference between cavity-mediated emission pathways leads to the formation of robust Bound States in the Continuum (BICs). These interference-induced dark states allow for the infinite trapping of excitation within the emitter-cavity subsystem, effectively shielding it from radiative decay. Our results extend the giant atom toolbox to the optical domain, offering a scalable architecture for integrated quantum photonics and quantum interconnects. Full article

The study systematizes the current state of knowledge on the morphological diversity of dispersed-phase particles in the most widely used lubricating greases, encompassing their shape, size, surface structure, and overall geometry. The extensive discussion of the diversity of grease thickener particles is supplemented with their microscopic images. Particular emphasis is placed on the influence of thickener particle morphology, the degree of their aggregation, and interparticle interactions on the rheological, mechanical, and tribological properties of grease formulations. The paper reviews recent advances in investigations of grease microstructure, with special emphasis on imaging techniques—ranging from dark-field imaging, through scanning electron microscopy, to atomic force microscopy—together with a discussion of their advantages and limitations in the assessment of particle morphology. A significant part of the work is devoted to rheological studies, which enable an indirect evaluation of the structural state of grease by analyzing its response to shear and deformation, thereby allowing inferences to be drawn about the micro- and mesostructure of lubricating greases. The historical development of rheological research on lubricating greases is also presented—from simple flow models, through the introduction of the concepts of viscoelasticity and structural rheology, to modern experimental and modeling approaches—highlighting the close relationships between rheological properties and thickener structure, manufacturing processes, composition, and in-service behavior of lubricating greases, particularly in tribological applications. It is indicated that contemporary studies confirm the feasibility of tailoring the microstructure of grease thickeners to specific lubrication conditions, as their characteristics fundamentally determine the rheological and tribological properties of the entire system. Full article

As one of the polymorphs of the gallium oxide family, ε gallium oxide (ε-Ga₂O₃) demonstrates promising potential in high-power electronic devices and solar-blind photodetection applications. However, the synthesis of pure-phase ε-Ga₂O₃ remains challenging through low-energy consumption methods, due to its metastable phase of gallium oxide. In this study, we have fabricated pure-phase and highly oriented ε-Ga₂O₃ thin films on c-plane sapphire substrates via thermal atomic layer deposition (ALD) at a low temperature of 400 °C, utilizing low-reactive trimethylgallium (TMG) as the gallium precursor and ozone (O₃) as the oxygen source. X-ray diffraction (XRD) results revealed that the in situ-grown ε-Ga₂O₃ films exhibit a preferred orientation parallel to the (002) crystallographic plane, and the pure ε phase remains stable following a post-annealing up to 800 °C, but it completely transforms into β-Ga₂O₃ once the thermal treatment temperature reaches 900 °C. Notably, post-annealing at 800 °C significantly enhanced the crystalline quality of ε-Ga₂O₃. To evaluate the optoelectronic characteristics, metal–semiconductor–metal (MSM)-structured solar-blind photodetectors were fabricated using the ε-Ga₂O₃ films. The devices have an extremely low dark current (<1 pA), a high photo-to-dark current ratio (>10⁶), a maximum responsivity (>1 A/W), and the optoelectronic properties maintained stability under varying illumination intensities. This work provides valuable insights into the low-temperature synthesis of high-quality ε-Ga₂O₃ films and the development of ε-Ga₂O₃-based solar-blind photodetectors for practical applications. Full article