Search Results (227)

We investigate how collisional interactions between the condensate and the thermal cloud influence the distinct dynamical regimes (Josephson plasma, phase-slip-induced dissipative regime, and macroscopic quantum self-trapping) emerging in ultracold atomic Josephson junctions at non-zero subcritical temperatures. Specifically, we discuss how the self-consistent dynamical inclusion of collisional processes facilitating the exchange of particles between the condensate and the thermal cloud impacts both the condensate and the thermal currents, demonstrating that their relative importance depends on the system’s dynamical regime. Our study is performed within the full context of the Zaremba–Nikuni–Griffin (ZNG) formalism, which couples a dissipative Gross–Pitaevskii equation for the condensate dynamics to a quantum Boltzmann equation with collisional terms for the thermal cloud. In the Josephson plasma oscillation and vortex-induced dissipative regimes, collisions markedly alter dynamics at intermediate-to-high temperatures, amplifying damping in the condensate imbalance mode and inducing measurable frequency shifts. In the self-trapping regime, collisions destabilize the system even at low temperatures, prompting a transition to Josephson-like dynamics on a temperature-dependent timescale. Our results show the interplay between coherence, dissipation, and thermal effects in a Bose–Einstein condensate at a finite temperature, providing a framework for tailoring Josephson junction dynamics in experimentally accessible regimes. Full article

The GaN-based green miniaturized light-emitting diode (mini-LED) is a key component for the realization of full-color display. Optimized passivation layers can alleviate the trapping of carriers by sidewall defects and are regarded as an effective way to improve the external quantum efficiency (EQE) efficiency of mini-LEDs. Since AlN has a closer lattice match to GaN compared to other heterogeneous passivation materials, we boosted the EQE of GaN-based green flip-chip mini-LEDs through the deposition of a lattice-compatible AlN passivation layer through atomic layer deposition (ALD) and a SiO₂ passivation layer through plasma-enhanced chemical vapor deposition (PECVD). Benefiting from reduced sidewall nonradiative recombination, the EQE of the green flip-chip mini-LED with a composite ALD-AlN/PECVD-SiO₂ passivation layer reached 34.14% at 5 mA, which is 34.6% higher than that of the green flip-chip mini-LED with a single PECVD-SiO₂ passivation layer. The results provide guidance for the realization of high-performance mini-LEDs by selecting lattice-compatible passivation layers. Full article

Glass-based microfluidic devices are essential for applications such as diagnostics and drug discovery, which utilize their optical clarity and chemical stability. This review systematically analyzes pulsed laser micromachining as a transformative technique for fabricating glass-based microfluidic devices, addressing the limitations of conventional methods. By examining three pulse regimes—long (≥nanosecond), short (picosecond), and ultrashort (femtosecond)—this study evaluates how laser parameters (fluence, scanning speed, pulse duration, repetition rate, wavelength) and glass properties influence ablation efficiency and quality. A higher fluence improves the material ablation efficiency across all the regimes but poses risks of thermal damage or plasma shielding in ultrashort pulses. Optimizing the scanning speed balances the depth and the surface quality, with slower speeds enhancing the channel depth but requiring heat accumulation mitigation. Shorter pulses (femtosecond regime) achieve greater precision (feature resolution) and minimal heat-affected zones through nonlinear absorption, while long pulses enable rapid deep-channel fabrication but with increased thermal stress. Elevating the repetition rate improves the material ablation rates but reduces the surface quality. The influence of wavelength on efficiency and quality varies across the three pulse regimes. Material selection is critical to outcomes and potential applications: fused silica demonstrates a superior surface quality due to low thermal expansion, while soda–lime glass provides cost-effective prototyping. The review emphasizes the advantages of laser micromachining and the benefits of a wide range of applications. Future directions should focus on optimizing the process parameters to improve the efficiency and quality of the produced devices at a lower cost to expand their uses in biomedical, environmental, and quantum applications. Full article

A functional measure encompasses quantum corrections and is explored in the fluid/gravity correspondence. Corrections to the response and transport coefficients in the second-order dissipative relativistic hydrodynamics are proposed, including those to the pressure, relaxation time, and shear relaxation time. Their dependence on the quark–gluon plasma (QGP) temperature sets a temperature dependence on the running parameter encoding the one-loop quantum gravity correction, driven by a functional measure. The experimental range of the bulk-viscosity-to-entropy-density ratio of the QGP, obtained by five different analyses (JETSCAPE Bayesian model, Duke, Jyväskylä–Helsinki–Munich, MIT–Utrecht–Genève, and Shanghai) corroborates the existence of the functional measure. Our results suggest that high-temperature plasmas could be used to experimentally test quantum gravity. Full article

Modern SiC-based materials are of paramount importance in that they serve as wear-resistant and thermal protectors and as next-generation single-photon sources for photonic and quantum solutions. Efforts are underway to identify more efficient methods of manufacturing SiC-based ceramic materials. The objective of this paper is to provide a description of the optimization of sintering SiC–TiC composites by the electroconsolidation method. The influence of titanium carbide content on the physical and mechanical properties of SiC–TiC composites obtained by spark plasma sintering (SPS) at a pressure of 45 MPa was studied. It was found that compared to sintered silicon carbide, the porosity of composites with 40 mol% TiC decreased from ~30% to 0%, the crack resistance increased from 2.9 to 6.1 MPa × m^0.5, and the hardness increased from 2.9 to 21.5 GPa. The influence of sintering temperature and holding time on SiC–TiC composites’ physical and mechanical properties during sintering at a pressure of 45 MP was also investigated. An increase in temperature from 1900 °C to 2000 °C resulted in an approximately 30% rise in the composite hardness. An extension of the time allotted for the sintering process from 30 to 45 min resulted in a decrease in both the fracture toughness and hardness of the material. The utilization of two- and three-dimensional vector spaces of material features was proposed as a novel methodology for the description of manufacturing process optimization. Full article

We conducted a comprehensive analysis of quantum molecular dynamics (QMD) simulation results for beryllium (Be) at metallic density and temperatures up to 32,000 K. Using the QMD results for the radial distribution function (RDF), velocity autocorrelation function (VACF), mean-squared displacement (MSD), and the diffusion coefficient of ions, we confidently assess the effectiveness of the Yukawa one-component plasma model in describing ion structure and transport properties. Additionally, we analyzed the applicability and accuracy of the Chapman–Enskog method for calculating the diffusion coefficient. We found that Yukawa model-based molecular dynamics (MD) simulations accurately capture ion dynamics, as evidenced by the VACF and MSD, when the Yukawa potential parameters are correctly chosen. Through our comparative analysis of the QMD, Yukawa–MD, and Chapman–Enskog methods, we clearly identified the effective coupling parameter values at which the Chapman–Enskog method maintains its accuracy. Importantly, while a model that reproduces the RDF of ions may not guarantee precise transport properties, our findings underscore the necessity of benchmarking plasma models against QMD results from real materials to validate their applicability and efficacy. Full article

The investigation of integral elastic cross-section (ICS), momentum transfer cross-section (MTCS), viscosity cross-section (VCS), absorption cross-section (ABSCS), and total cross-section (TCS) of atoms by electron ($e^{-}$) and positron ($e^{+}$) impact is very crucial and essential for understanding fundamental atomic processes and their applications in various fields such as plasma physics, molecular physics, and astrophysics. This study investigates and analyses the ICS, MTCS, VCS, ABSCS, and TCS of the atoms, Li, Be, B, Ti, and W, over a wide energy range. By employing the computational Optical Potential Method (OPM) and quantum scattering integrated in a computational package, ELSEPA (Elastic scattering of electrons and positrons by atoms, positive ions and molecules), the cross-sections of atoms by electron and positron impact are calculated. The present results shows good agreement with all the experimental and theoretical data available in the literature. The obtained cross-sections may facilitate the development of accurate models for plasma simulations and fusion research. Full article

Heavy metal ion (HMI) contamination poses significant threats to public health and environmental safety, necessitating advanced detection technologies that are rapid, sensitive, and field-deployable. While conventional methods like atomic absorption spectroscopy (AAS) and inductively coupled plasma mass spectrometry (ICP-MS) remain prevalent, their limitations—including high costs, complex workflows, and lack of portability—underscore the urgent need for innovative alternatives. This review consolidates advancements in the last five years in microfluidic technologies for HMI detection, emphasizing their transformative potential through miniaturization, integration, and automation. We critically evaluate the synergy of microfluidics with cutting-edge materials (e.g., graphene and quantum dots) and detection mechanisms (electrochemical, optical, and colorimetric), enabling ultra-trace detection at parts-per-billion (ppb) levels. We highlight novel device architectures, such as polydimethylsiloxane (PDMS)-based labs-on-chip (LOCs), paper-based microfluidics, 3D-printed systems, and digital microfluidics (DMF), which offer unparalleled portability, cost-effectiveness, and multiplexing capabilities. Additionally, we address persistent challenges (e.g., selectivity and scalability) and propose future directions, including AI integration and sustainable fabrication. By bridging gaps between laboratory research and practical deployment, this review provides a roadmap for next-generation microfluidic solutions, positioning them as indispensable tools for global HMI monitoring. Full article

The dynamics of plasmon polaritons (PPs) in a periodic lattice of dispersed nanorings (NRs) with embedded quantum nanoemitters (NEs) arranged according to the Cassini–Bernoulli lemniscate (LB) is studied. The field structure and the dynamics of the NE (quantum polarization) depend significantly on the plasma frequency ${\omega }_p$ of the NR. We show that in the vicinity of the intersection of the LB branches (a region of high emitter density) located in the nanoring gaps, there is a significant enhancement of the optical field intensity and quantum correlations in the emitter subsystem. This effect may allow the coherent amplification of terahertz PPs (studied recently via free-electron-stimulated emission) in a lattice of NRs with the emission of embedded NEs. Full article

The origin and acceleration of high-energy particles, constituting cosmic rays, is likely to remain an important topic in modern astrophysics. Among the two categories galactic and solar cosmic rays, the latter are much less investigated. The primary source of solar cosmic ray particles are impulsive explosions of the magnetized plasma, known as solar flares and coronal mass ejections. These particles, however, are characterized by relatively low energies compared to their galactic counterparts. In this work, we explore the resonance wave–wave (RWW) interaction between the polarized electromagnetic radiation emitted by the solar active regions and the quantum waves associated with high-energy, relativistic electrons generated during solar flares. Mathematically, the RWW interaction problem boils down to analyzing a Klein–Gordon Equation (spinless electrons) embedded in the electromagnetic field. We find that RWW could accelerate the relativistic electrons to enormous energies even comparable to energies in the galactic cosmic rays. Full article

In this work, we present an improved model for ionization potential depression (IPD) in dense plasmas that builds upon the approach introduced by Lin et al., which utilizes a dynamical structure factor (SF) to account for ionic microfield fluctuations. The main refinements include the following: (1) replacing the Wigner–Seitz radius with an ion-sphere radius, thereby treating individual ionization events as dynamically independent; (2) incorporating electron degeneracy through a tailored interpolation between Debye–Hückel and Thomas–Fermi screening lengths. Additionally, we solve the Saha equation iteratively, ensuring self-consistent determination of the ionization balance and IPD corrections. These modifications yield significantly improved agreement with recent high-density and high-temperature experimental data on warm dense aluminum, especially in regimes where strong coupling and partial degeneracy are crucial. The model remains robust over a broad parameter space, spanning temperatures from 1 eV up to 1 keV and pressures beyond the Mbar range, thus making it suitable for applications in high-energy-density physics, inertial confinement fusion, and astrophysical plasma research. Our findings underscore the importance of accurately capturing ion microfield fluctuations and electron quantum effects to properly describe ionization processes in extreme environments. Full article

{CdO/ZnO}_m superlattices (SLs) have been grown on c-plane sapphire substrates by plasma-assisted molecular beam epitaxy (PA-MBE). The observation of satellite peaks in the XRD studies of the as-grown and annealed samples confirms the presence of a periodic superlattice structure. The properties of as-grown and annealed SLs deposited on c-oriented sapphire were investigated by transmission electron microscopy, X-ray diffraction and temperature dependent PL studies. The deformation of the SLs structure was observed after rapid thermal annealing. As the thermal annealing temperature increases, the diffusion of Cd ions from the quantum well layers into the ZnO barrier increases. The formation of CdZnO layers causes changes in the luminescence spectrum in the form of peak shifts, broadening and changes in the spacing of the satellite peaks visible in X-ray analysis. Full article

QDT (quantum defect theory) is an effective technique for calculating processes involving highly excited (Rydberg) states of atoms, ions, and molecules with one valence electron outside filled shells, whose spectrum generally resembles a hydrogen-like atom’s spectrum. At the expense of some modification of QDT, in this paper, we extend its applicability to describe low- and intermediate-excited levels of atoms with more complex spectra (on the example of atomic sulfur S I). Transitions between just such states are responsible for the infrared (IR) spectra of atoms. While the quantum defects (QDs) of the highly excited Rydberg levels are determined by the energies of individual levels near the ionization threshold, the radial wave functions of low excited electronic states, in the framework of our modification of QDT, include the QD dependence on energy over a wide energy range; this dependence is determined from the whole spectral series. We show that, outside the atomic core domain, the electron radial functions calculated using modified semi-phenomenological QDT agree well with ab initio calculations. As another assessment of QDT accuracy, we show satisfactory agreement of the probabilities of dipole transitions in S I, taken from the NIST Atomic Spectra Database, with our QDT calculations. We perform an indirect experimental verification of QDT on the basis of spectra of S I in gas-discharge plasma measured by time-resolved high-resolution Fourier transfer spectroscopy (FTS). The Boltzmann plot built from our measured spectra demonstrates that QDT provides a satisfactory approximation for calculating the experimental lines’ intensities. Full article

This study introduces an organic light-emitting diode (OLED) light extraction method using a wavy-patterned polydimethylsiloxane (PDMS) substrate created via oxygen (O₂) plasma treatment. A rapid fabrication process adjusted the flow, pressure, duration, and power of the O₂ plasma treatment to replicate the desired wavy structure. This method allowed the treated samples to maintain over 90% total transmittance and enabled controlled haze adjustments from 10% to 70%. Finite-difference time-domain (FDTD) simulations were employed to determine optimal amplitudes and periods for the wavy structure to maximize optical performance. Further experiments demonstrated that bottom-emitting green fluorescent OLEDs constructed on these substrates achieved an external quantum efficiency (EQE) of 3.5%, representing a 97% improvement compared to planar PDMS OLEDs. Additionally, color purity variation was minimized to 0.044, and the peak wavelength shift was limited to 10 nm, ensuring consistent color purity and intensity even at wide viewing angles. This study demonstrates the potential of this cost-effective and efficient method in advancing high-quality display. Full article

An Integrated Process Intensification (IPI) technology-based roadmap is proposed for the utilization of renewables (water, air and biomass/unavoidable waste) in the small-scale distributed production of the following primary products: electricity, H₂, NH₃, HNO₃ and symbiotic advanced (SX) fertilizers with CO₂ mineralization capacity to achieve negative CO₂ emission. Such a production platform is an integrated intensified biorefinery (IIBR), used as an alternative to large-scale centralized production which relies on green electricity and CCUS. Hence, the capacity and availability of the renewable biomass and unavoidable waste were examined. The critical elements of the IIBR include gasification/syngas production; syngas cleaning; electricity generation; and the conversion of clean syngas (which contains H₂, CO, CH₄, CO₂ and N₂) to the primary products using nonthermal plasma catalytic reactors with in situ NH₃ sequestration for SA fertilizers. The status of these critical elements is critically reviewed with regard to their techno-economics and suitability for industrial applications. Using novel gasifiers powered by a combination of CO₂, H₂O and O₂-enhanced air as the oxidant, it is possible to obtain syngas with high H₂ concentration suitable for NH₃ synthesis. Gasifier performances for syngas generation and cleaning, electricity production and emissions are evaluated and compared with gasifiers at 50 kWe and 1–2 MWe scales. The catalyst and plasma catalytic reactor systems for NH₃ production with or without in situ reactive sequestration are considered in detail. The performance of the catalysts in different plasma reactions is widely different. The high intensity power (HIP) processing of perovskite (barium titanate) and unary/binary spinel oxide catalysts (or their combination) performs best in several syntheses, including NH₃ production, NO_x from air and fertigation fertilizers from plasma-activated water. These catalysts can be represented as BaTi_1−vO_3−x{#}_yN_z (black, piezoelectric barium titanate, bp-{BTO}) and M⁽¹⁾_3−jM⁽²⁾_kO_4−m{#}_nN_r/SiO₂ (unary (k = 0) or a binary (k > 0) silane-coated SiO₂-supported spinel oxide catalyst, denoted as M/Si = X) where {#} infers oxygen vacancy. HIP processing in air causes oxygen vacancies, nitrogen substitution, the acquisition of piezoelectric state and porosity and chemical/morphological heterogeneity, all of which make the catalysts highly active. Their morphological evaluation indicates the generation of dust particles (leading to porogenesis), 2D-nano/micro plates and structured ribbons, leading to quantum effects under plasma catalytic synthesis, including the acquisition of high-energy particles from the plasma space to prevent product dissociation as a result of electron impact. M/Si = X (X > 1/2) and bp-{BTO} catalysts generate plasma under microwave irradiation (including pulsed microwave) and hence can be used in a packed bed mode in microwave plasma reactors with plasma on and within the pores of the catalyst. Such reactors are suitable for electric-powered small-scale industrial operations. When combined with the in situ reactive separation of NH₃ in the so-called Multi-Reaction Zone Reactor using NH₃ sequestration agents to create SA fertilizers, the techno-economics of the plasma catalytic synthesis of fertilizers become favorable due to the elimination of product separation costs and the quality of the SA fertilizers which act as an artificial root system. The SA fertilizers provide soil fertility, biodiversity, high yield, efficient water and nutrient use and carbon sequestration through mineralization. They can prevent environmental damage and help plants and crops to adapt to the emerging harsh environmental and climate conditions through the formation of artificial rhizosphere and rhizosheath. The functions of the SA fertilizers should be taken into account when comparing the techno-economics of SA fertilizers with current fertilizers. Full article