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Evolution of intragranular pores in potassium niobate ceramics during sintering
Remote plasma for damage-controlled fabrication of single-photon emitters in ultrathin hexagonal boron nitride
Hexagonal boron nitride (hBN) hosts bright and robust color centers, with emission in the ultraviolet to near-infrared range, that are generally obtained either by activating pre-existing atomic defects or by purposefully introducing strain, vacancies, or impurities. Controlled fabrication remains a challenge as color centers often form on extended structural defects, including pre-existing flake edges, holes, and folds, as well as unintended damage sites created during vacancy generation. Here, we introduce a remote argon plasma technique to produce vacancies while minimizing material damage. Additionally, by independently tuning the ion flux and energy, we engineer large arrays of single-photon emitters (SPEs). Critically, the SPEs form away from nanoscale non-uniformities, in pristine flake regions. Our processing approach thus enables the formation of stable SPEs with bulk properties in atomically thin hBN. The noninvasive formation of color centers in 2D materials opens multiple pathways toward their applications in sensing and quantum photonics.
The benefit of advanced mapping techniques to address the spatial distribution of soil sulfur—total, gypsum-based, and total-reduced—in the dried Sawa Lakebed
A highly sensitive genetically encoded red cAMP sensor for multiplex imaging in vivo
Phonon-modulated magnon transport via ferromagnetic resonance in a nonlocal YIG/Pt device
Owing to magnetostrictive effects, nonlocal magnon transport in yttrium iron garnet (YIG) is often accompanied by phonon excitation. However, the influence of these phonons on magnon spin transport remains unclear. In our experiment, an external microwave field is applied to excite ferromagnetic resonance (FMR) in the YIG during nonlocal magnon transport measurements. We observe that an additional signal emerges in the thermal magnon transport. Angular-dependent measurements under varying magnetic fields further reveal that this additional signal is well described by our Landau–Lifshitz–Gilbert (LLG) simulation when enhanced magnetoelastic coupling is considered. This result indicates that the signal originates from the rotational lattice motion driven by magnetization precession, which generates phonons that subsequently couple to propagating magnons. This behavior contrasts with previously reported magnon–magnon scattering and parametric pumping, which occur strictly under resonant FMR conditions and require nonlinear excitation. Our results provide evidence that phonons actively participate in magnon spin transport and suggest viable opportunities for developing high-speed, phonon-assisted magnonic devices.
A closed‑form reaction‑kinetics model for LET‑ and oxygen‑dependent hydroxyl radical availability under irradiation
Dynamics of dislocation formations and their impacts on exsolution in Ru-doped perovskite oxide
Contribution of surface state to dislocation dissociation in metallic solids
A surface state (Es) is generated in the electronic band structure when a stacking fault (SF) forms due to the violation of the translational symmetry of a crystalline structure at dissociated partial dislocation cores. We found that Es demonstrates a linear relation with the SF energy (SFE), which was evaluated via transmission electron microscopy (TEM) for nonferromagnetic metallic solids, indicating that the SF width is determined by ES on the slip plane for each crystalline structure. Based on this observed relation, for lead, the SFE calculated using density functional theory (48 mJ/m2) is inconsistent with that evaluated via TEM (8 mJ/m2). Furthermore, the relation reveals various peculiarities of aluminum, such as the deep Es resulting from the projected bulk band widely spread beneath the Fermi level and the narrower SF compared with those of other face-centered cubic metallic solids.
Single-phase to three-phase DC-link boost converter with reduced controlled switch count
Abstract Three-phase motors are used in a variety of applications, such as industrial machinery, water pumping stations, and electric vehicles and transportation systems. They may be easily operated from a single-phase power source by using a suitable power converter to drive three phase motors from single-phase ac source. This paper proposes a single-phase to three-phase (SPTTP) converter with boosting capability of three-phase output voltages. The proposed configuration reduces the number of switches which is only six semiconductors and increasing the three-phase output voltages of single-phase ac source. Moreover, it improves the input and output currents profile of total harmonic distortion (THD) without using another switches in rectifier side. The fewer semiconductor switches and passive components leads to lower power losses and improved efficiency. The toggling control strategy employs a straightforward logic control circuit that is dependent on Sinusoidal Pulse Width Modulation (SPWM) technique. The modulation technique is simple approach rather than Space Vector Pulse Width Modulation (SVPWM) which used in the compared topologies. The architecture’s robustness and effectiveness are verified through the use of MATLAB/SIMULINK. The simulation analysis is verified by setting up and testing a prototype for this topology in the laboratory using a dSPACE-1104. Finally, the desired circuit is approved by the simulation and experimental results, which are examined by the good similarity under a variety of conditions.
Cold sintering of hybrid copper-iodides in transparent ceramics using dolomitization-inspired densification
Spectroscopic imaging ellipsometry for spatially resolved mapping of layer-by-layer oxidation in WSe2
Tungsten diselenide is a prominent candidate for nanoscale electronics and complementary metal–oxide–semiconductor technology due to its controllable p-type and n-type doping that is achievable through selective oxidation. However, characterizing the resulting oxide quality often relies on destructive or slow metrology. In this work, we demonstrate spectroscopic imaging ellipsometry (SIE) as a noninvasive technique to characterize the oxidation state of two-dimensional materials, providing spatially resolved measurements of layer thickness and uniformity. We apply this method to compare few-layer WSe2 after thermal or plasma-based oxidation treatments. We show that plasma oxidation enables a highly controllable conversion of individual WSe2 layers into uniform sub-stoichiometric tungsten oxide (WOx), whereas thermal oxidation in atmospheric conditions yields a rough interface characterized by non-uniform oxide formation and blistering. Using SIE, we quantify a layer-by-layer conversion ratio, where a single WSe2 monolayer transforms into ∼1.6 nm of WOx during plasma oxidation. These findings, corroborated by atomic force microscopy, highlight the capability of SIE to resolve dielectric evolution and interface quality in layered semiconductors.
Band gap engineering in Al, Cu, N and Al/Cu Co-doped ZnO thin films: experimental study and quantum machine learning prediction
Abstract This study investigates RF magnetron sputtered ZnO thin films doped with Al, Cu, N and co-doped with Al/Cu, followed by post deposition annealing at 300-600 °C. Structural and compositional characterization was performed by X ray diffraction (XRD) and energy dispersive spectroscopy (EDS), while surface morphology and roughness were assessed by atomic force microscopy (AFM). Optical band gaps were extracted experimentally from UV-Vis spectra using Tauc analysis and Urbach energy evaluation. Key descriptors, lattice constants, crystallite size, root mean square (RMS) roughness, and Urbach energy were used as input features for a data driven quantum machine learning model. A variational quantum regression (VQR) model trained on these structural and processing descriptors achieved a mean squared error (MSE) of 0.0576 eV in predicting band gap values, accurately capturing trends induced by dopant type and annealing temperature. By combining systematic experimental tuning with quantumn enhanced predictive modeling, the work provides an integrated framework for accelerated band gap engineering of ZnO thin films, with direct implications for optimizing transparent conductive oxides and other optoelectronic materials.
Monolithic integration of p- and n-type doped 2D WSe2 for wafer-scale complementary logic circuits
Enhanced thermoelectric performance and observation of WAL effect in Se-substituted BiSbTe3 single crystals
Bi–Sb–Te-based materials are benchmark thermoelectrics for room temperature applications owing to their optimal electronic band structure that yields a large value of thermopower (S ∼ 300 μV/K), ultralow thermal conductivity (∼1 W/mK), combined with a convenient synthesis procedure. To further improve the thermoelectric performance of these materials, new strategies are required without compromising their intrinsic electronic properties. The isoelectronic substitution can be a rational approach, as it is primarily employed to reduce the lattice thermal conductivity with minimal alteration of the electronic structure of the material system. Therefore, in the present work, we investigated the effect of Se substitution in BiSbTe3 single crystals grown by the modified Bridgman method. X-ray diffraction studies confirm that the crystal structure of the material is maintained with Se substitution. Contrary to the simple expectation, we observe a dramatic non-monotonic evolution in its electronic transport behavior, in particular, the optimized composition BiSbTe2.5Se0.5 exhibits a sevenfold enhancement in its thermoelectric power factor compared to the pristine BiSbTe3, which can be attributed to a massive reduction in its electrical resistivity. Upon further increasing Se substitution drives a metal-to-semiconductor transition in BiSbTe1.5Se1.5, displaying a negative magnetoresistance and weak antilocalization signatures. Density functional theory calculations performed using Vienna ab initio simulation package reveal that isoelectronic substitution induces significant modifications in the electronic structure of Bi–Sb–Te-based alloys, which is in accordance with the experimentally observed transport properties. Our findings therefore demonstrate that controlled isoelectronic substitution can effectively tune the electronic properties of Bi–Sb–Te-based alloys and thereby provide a reliable route for thermoelectric performance optimization.
Project delivery methods regulation and performance of construction projects in Uganda
Long-read deep sequencing reveals high rates of multilineage transmission and rapid viral population changes in acute HIV infection
Abstract Understanding the selective forces acting upon HIV early in infection is crucial to design prevention strategies. By leveraging deep sequencing and the short diagnostic intervals of the FRESH and RV217 cohorts between the last-negative and first-positive RNA tests (median 4 days), we captured a precise and early snapshot of acute HIV infection. The frequency of multiple transmitted viruses of 37% in these as well as placebo recipients from the AMP trials (NCT02716675 and NCT02568215) was higher than previously published, with the true frequency likely to be higher. The relative abundance of lineages fluctuated substantially over time in two-thirds of the multilineage infections, generating uncertainty in identifying the specific viruses that were transmitted and founding the infection. At the population level, viral populations exhibited limited diversity and selection on the Gag and Env proteins at the earliest times examined, with sites inferred to be undergoing negative selection most evident. These data may help explain vaccination failures and provide new targets for prevention.
Investigative study of Mg in GaN and AlN with density functional theory
The relatively high activation energy of the Mg acceptor in GaN and AlN is one factor that limits free hole concentrations in Mg-doped GaN, AlN, and AlGaN. Impurity band conduction has been observed and proposed as a mechanism to overcome these limitations of free carrier concentrations. Full impurity band conduction requires wavefunction overlap and, depending on the dimensions of the wavefunction, higher doping concentrations. At lower dopant concentrations, delocalized impurity states can still impact conduction through Anderson conduction mechanisms. It is therefore critical to understand the properties of dopants and the extent of delocalization of the impurity wavefunctions to better understand what types of conduction may be possible in these hosts. This work utilizes hybrid functional density functional theory to explore possible configurations of the Mg acceptor in GaN and AlN, and explores whether any Mg defects have properties that could facilitate impurity band conduction. Two configurations of the Mg acceptor were found in GaN and AlN, with one configuration exhibiting delocalized defect wavefunctions. Increasingly larger defect supercells were used to explore the properties of these defects further until delocalized wavefunctions were fully contained within the supercell boundaries. Doing so also led to convergence of Kohn–Sham eigenvalues, confirming that the delocalized defect state becomes isolated in larger supercells.
Multistage assessment of construction delay factors using expert evaluation and real project data
Abstract Construction delays remain a major challenge, especially in developing countries where financial, administrative, and resource constraints intensify schedule disruptions. This study identifies and prioritizes construction delay factors through a three-phase research framework consisting of a literature review, an expert survey evaluation, and validation using real-life construction projects in Egypt. First, a comprehensive review of global literature led to the identification of 98 delay factors, which were classified into four main categories: owner-related factors (25 factors, 26%), contractor-related factors (34 factors, 35%), consultant/design-related factors (14 factors, 14%), and external factors (25 factors, 26%). Second, an expert survey was conducted to evaluate the previously identified delay factors. This phase employed a composite scoring approach that integrates both the frequency of occurrence and the impact of each factor to rank the most critical delay drivers. The findings indicate that owner-related factors constitute the most significant sources of delay, accounting for approximately 50% of the top 22 critical factors. Finally, the reliability of these findings was validated using the top 22 factors and a dataset of 141 real construction projects, showing strong alignment between the survey-based rankings and actual outcomes. Key factors, such as frequent change orders and design modifications, remained top-ranked, while some factors ranked higher or lower in practice, indicating minor variations in their relative importance under real project conditions. The study contributes a validated dataset of delay factors derived from both expert evaluation and real project evidence, providing a strong foundation for future predictive modeling applications using artificial intelligence and machine learning.
High-performance uncooled mid-infrared lead salt photodetectors: Revealing surface passivation and charge transport mechanisms
Uncooled mid-infrared lead-salt photodetectors are considered promising candidates for next-generation infrared optoelectronic devices that meet the small size, low weight, high performance, low power consumption, and low price (SWaP3) standards. However, research on the internal charge transport mechanisms of these devices is currently very limited, resulting in a lack of deep understanding of the key transport mechanisms, which seriously hinders the development of uncooled mid-infrared photodetectors. Here, high-performance uncooled PbSe photodetectors with different iodine contents were fabricated, achieving a high specific detectivity of 1.68 × 1010 Jones at 300 K. Through the temperature dependence of the conductivity, the charge transport mechanisms at different temperatures were revealed, showing that at low temperatures, charge transport follows the variable-range hopping mechanism, whereas near room temperature, grain boundary barrier transport dominates, with a transition temperature of Tc = 217.4 K. A grain boundary transport model for charge carriers was proposed, revealing the regulatory effect of iodination on the device's grain boundary barriers. The study also investigated the space charge effects within the devices, diffusion currents, and electron tunneling characteristics, uncovering for the first time the space charge-limited transport mechanism and the Poole–Frenkel effect under high bias conditions. The findings provide new insights into device physics for high-performance uncooled lead-salt photodetectors.