Search Results (191)

The calculation of the limiting efficiency and structural optimization of solar cells based on the detailed balance principle is systematically investigated in this study. Through modeling and numerical simulations of various cell architectures, the theoretical efficiency limits of these structures under AM1.5G (Air Mass 1.5 Global) spectrum were quantitatively evaluated. Through a comprehensive consideration of the effects of bandgap and composition, the Al_0.03Ga_0.97As/Ge (1.46 eV/0.67 eV) cell configuration was determined to achieve a high theoretical efficiency of 43.0% for two-junction cells while maintaining satisfactory lattice matching. Furthermore, the study proposes that incorporating a Ga_0.96In_0.04As (8.3 nm)/GaAs_0.77P_0.23 (3.3 nm) strain-balanced multiple quantum wells (MQWs) structure enables precise bandgap engineering, modulating the effective bandgap to the optimal middle-cell value of 1.37 eV, as determined by graphical analysis for triple junctions. This approach effectively surpasses the efficiency constraints inherent in conventional bulk-material III–V semiconductor solar cells. The results demonstrate that an optimized triple-junction solar cell with MQWs can theoretically achieve a conversion efficiency of 51.5%. This study provides a reliable theoretical foundation and a feasible technical pathway for the design of high-efficiency solar cells, especially for the emerging MQW-integrated III–V semiconductor tandem cells. Full article

To address the imbalance between the “ecological advantage” and “economic benefit” of wooden structure buildings, this study examines two structural construction methods utilizing inexpensive and readily available small-diameter round timber as the primary material. It demonstrates the advantages of these two structural systems in terms of material consumption, life cycle carbon emissions, and economic efficiency. Through the research methods and processes of “Preliminary analysis–Proposing the construction system–The feasibility analysis of structural technology–Efficiency assessment”, the sustainable wood structure technical system suitable for the development of China is explored. The main conclusions are as follows: (1) Employing the preliminary analysis method, this paper examines and analyzes construction cases that primarily utilize small-diameter round timber as the main material. It delineates specific construction types based on the characteristics of small-diameter round timber. Additionally, it technically reconstructs the methodology for utilizing small-diameter round timber. (2) Two lattice structural systems are proposed, leveraging the mechanical properties and fundamental morphological characteristics of inexpensive and readily available small-diameter round timber of fast-growing Northeast larch. The technical feasibility of these two small-diameter log structure systems is validated through simulation analysis of their spatial threshold suitability. (3) This study conducted a comprehensive comparison between the two small-diameter round timber structural systems and the conventional grain-parallel glued laminated timber (Cross-Laminated Timber) frame structural systems. The analysis was performed from three perspectives. As the primary structural material, grain-parallel glued laminated timber frame structural systems exhibits significant advantages in terms of timber utilization per unit area of the structural system. From a life cycle carbon emission analysis perspective, compared to grain-parallel glued laminated timber frame structures, small-diameter round timber structures can achieve carbon emission reductions ranging from 79.19% to 97.74%. Additionally, the unit area cost of small-diameter round timber structures is reduced by 21.02% to 40.42% relative to grain-parallel glued laminated timber frame structures. Consequently, it can be concluded that small-diameter round timber structural systems possess technical feasibility and construction advantages for small and medium-sized buildings, offering practical value in optimizing technical systems to meet the objective needs of ecological construction. Full article

Thermoluminescence has a long and successful history in applied radiation dosimetry, as well as in a wide range of other applications and basic research. However, there is a dichotomy that, despite the many commercial successes, there continue to be entrenched systematic errors in data collection, signal processing, and models. This overview offers suggestions to address these issues. Improving initial data collection is certainly feasible and may offer deeper insights into the potential mechanisms of thermoluminescence. There is an extremely complex challenge in suggesting and confirming models for lattice sites that generate luminescence signals. Currently, such models are highly speculative and simplistic. In reality, they should involve not only immediate lattice sites but also extremely long-range interactions. Weaknesses in data collection and models impact and generate errors in the extraction of activation energies and frequency factors that are routinely ascribed to data analysis. Overall, it is possible to suggest ways to improve data collection and slightly improve modelling of relevant lattice sites and parameters such as their activation energies, but in reality, these factors will always be speculative and imprecise. Fortunately, this does not inhibit the extension of the technique into other areas of application, but the suggested improvements will enable greater diversity. Full article

We aimed to validate the feasibility of combining ultra-widefield (UWF) fundus photography with targeted swept-source optical coherence tomography (SS-OCT) for clinical decision-making regarding a prophylactic laser therapy. For this purpose we enrolled 119 patients (135 eyes) who, basis on fundus examination, were eligible for prophylactic photocoagulation of degenerative retinal lesions. Eyes were classified into two groups: (1) justified laser, when SS-OCT confirmed vitreoretinal traction and/or subretinal fluid beneath the neurosensory retina; and (2) non-justified laser, when SS-OCT did not confirm these criteria. Using this SS-OCT-guided UWF approach, we found that 25.1% of eyes that initially qualified for laser based on clinical examination did not meet the SS-OCT criteria. Patients in the justified laser group were significantly younger than those in the non-justified group. Horseshoe retinal tears, lattice degeneration and snail-track degenerations, multiple lesions, and lesions located in the far and mid-periphery were significantly more frequent in the justified laser group than in the non-justified group. By contrast, the prevalence of operculated holes, bilateral lesions, and degenerative lesions in patients with a retinal detachment in the fellow eye did not differ between groups. Our findings suggest the SS-OCT-guided UWF imaging may refine patient selection for prophylactic laser therapy. Full article

Scandium (Sc)-doped aluminum nitride (AlN) thin films are critical for high-frequency, high-power surface acoustic wave (SAW) devices. A composite Sc doping strategy for AlN thin films is proposed, which combines magnetron sputtering pre-doping with post-doping via ion implantation to achieve gradient doping and tailor microstructural characteristics. The crystal structure, surface composition, and microstructural defects of the films were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). Results indicate that the Sc content in pre-doped ScAlN films was optimized from below 10 at.% to above 30 at.%, while the films maintained a stable (002) preferred orientation. XPS analysis confirmed the formation of Sc-N bonds, and EDS mapping revealed a gradient distribution of Sc within the subsurface region, extending to a depth of approximately 200 nm. High-resolution TEM revealed localized lattice distortions and surface amorphization induced by ion implantation. This work demonstrates the feasibility of ion implantation as a supplementary doping technique, offering theoretical insights for developing AlN films with high Sc doping concentrations and structural stability. These findings hold significant potential for optimizing the performance of high-frequency, high-power SAW devices. Full article

Metal additive manufacturing (AM) offers promising advancements in producing implants with complex geometry for biomedical applications, where accuracy and near-net-shape production are essential. Metal AM by laser powder bed fusion (PBF-LB) is a promising route to produce biodegradable iron implants made of complex lattice structures. However, processing windows for pure iron remain poorly defined. This work focuses on optimizing PBF-LB parameters for pure iron using a design of experiments (DoE) approach on bulk samples of different geometries to evaluate different parameters. Hatch laser power, scanning speed, hatch distance and point distance were varied and their effect on porosity, surface roughness and dimensional accuracy was evaluated. This was followed by the fabrication of rhombitruncated cuboctahedron (RTCO) lattice structures with the best parameters previously defined for the bulk samples. The best parameter set (hatch laser power 180 W, scanning speed 600 mm/s, hatch distance 110 µm and point distance 12 µm, corresponding to a volumetric energy density of 90.9 J/mm³) produced bulk samples with a porosity as low as 0.07% (99.93% density) measured in polished sections. Using these parameters, RTCO lattices with designed relative densities of 10.28%, 35.29% and 65.16% were successfully manufactured with small geometric deviations and good control of strut thickness and relative density. The results of this study define a robust PBF-LB processing window for pure iron and demonstrate the feasibility of producing geometrically controlled, biodegradable iron lattice structures suitable for future load-bearing biomedical applications. Full article

Anion exchange membrane fuel cells (AEMFCs) are the most feasible choice of catalyst due to their high efficiency and scale of commercialization. However, the challenge posed by the sluggish kinetics of AEMFCs can only be countered by an effective electrocatalyst that enhances the reaction kinetics and, thereby, the fuel cell performance. The Pd-Co/C cathode catalyst is a promising choice of electrocatalyst, with the phenomenon of alloying playing a key role at appropriate temperatures and residence time distributions of annealing due to the influence of the lattice parameter, electrochemically active surface area (ECSA), and particle size. After completing the synthesis of 20 wt.% Pd-Co/C, the catalyst was treated under various annealing and loading conditions. This was subsequently followed by a series of physicochemical and electrochemical characterizations that verified the successful synthesis of the catalyst material, paving a path to optimizing the annealing temperature, annealing residence time, and catalyst loading. Further, proceeding with the fuel cell test runs with multiple profiles of the above parameters resulted in the optimization of the annealing temperature, residence time of annealing, and catalyst loading, and it was subsequently concluded that the best performance of the fuel cell was achieved when the Pd-Co/C catalyst was annealed at 500 °C for a duration of 1 h and loaded at 0.25 mg/cm², which resulted in an impeccable power density of 724 mW/cm². Full article

To explore the potential of new information transmission windows, this work presents a broadband plasmonic filter based on gold-deposited silicon photonic crystal fiber (PCF) operating in mid-infrared regime numerically, using the finite element method (FEM). The simulation results indicate that the interaction between the high-refractive-index pure silicon material and the gold layer can cause a shift of the resonance central point to the mid-infrared band, which provides the prerequisite for mid-infrared filtering. When the cladding holes’ diameter is 1.3 µm, the inner holes’ diameter is 1.04 µm, the diameter of the holes located on both sides of the core region is 2.08 µm, the gold-coated holes’ diameter is 2.08 µm, the lattice constant is 2 µm, and the gold thickness is 50 nm, this PCF can operate in the mid-infrared band near the central wavelength of 3 µm. The 1 mm long PCF polarizer exhibits a maximum extinction ratio (ER) of −43.5 dB at 3 µm and a broad operating bandwidth of greater than 820 nm with ER better than −20 dB. Additionally, it also possesses high fabrication feasibility. This in-fiber polarization filter, characterized by its comprehensive performance and ease of fabrication, aids in exploring the development potential of high-speed and large-capacity modern communication networks within new optical bands and contributes to new photonic computing and sensing. Full article

This study proposes a novel multi-porous heat exchanger (MPHEX) as a passive, sustainable alternative to variable refrigerant flow (VRF) air conditioning systems, addressing the growing environmental burden of cooling demand. Through high-fidelity Lattice Boltzmann Method simulations of coupled heat and fluid transport, the MPHEX design is optimized to minimize exergy destruction. A case study for Tunisian conditions demonstrates that permeability optimization, when combined with solar-assisted preheating, reduces total exergy destruction by over 60% and increases the coefficient of performance (COP) by up to 20%, all while eliminating active mechanical regulation. The numerical results confirm strong experimental feasibility, positioning the MPHEX as a scalable, low-energy, and low-maintenance cooling solution for sun-rich regions. Full article

In many mountainous areas of China, frequent geological disasters pose a serious threat to human life and property. The Luding “9.5” earthquake triggered a large number of landslide disasters, causing serious loss of life and property. Therefore, it is extremely urgent to carry out research on the stability analysis and treatment methods of landslides in the Luding area. In this paper, the Caiyangba landslide in Yanzigou Town, Luding County, is taken as the research object. The slope model is constructed by Midas to study the stability development law of Caiyangba landslide under different rainfall conditions and seismic conditions, and to explore the feasibility of the “anchor lattice treatment method”. The results show that the “anchor lattice treatment method” can effectively improve the stability of the slope under rainfall conditions. The improvement effect of slope stability decreases with the increase in rainfall duration and rainfall. The development law of the slope stability coefficient with rainfall duration in WMG (the working condition of not adopting the “anchor lattice treatment method” is referred to as WMG) and MG (the working condition of adopting the “anchor lattice treatment method” is referred to as MG) conditions conform to the development law of exponential function, and the expression of instantaneous change rate of slope stability coefficient is derived. The above function can also well explain the development law of X-direction displacement and Y-direction displacement of SP (school: monitoring point) and RP (road: monitoring point); the development law of the instantaneous change rate of displacement. Under the influence of ground motion, the improvement effect of the “anchor lattice treatment method” on the slope stability coefficient is limited, but the improvement effect of slope stability increases with the increase in seismic intensity. The slope stability coefficient and the displacement of SP and RP show obvious fluctuation with time, and the fluctuation law is similar to that of ground motion records. It is recommended to add a gravity-retaining wall at the foot of the slope. The teaching building reduces the number of floors and increases the number of pile foundations. Roads should restrict the passage of heavy vehicles, such as cars and strictly stacked items. The above results can provide a theoretical reference for the sustainable treatment and sustainable development of landslides in the Luding area. Full article

The influence of M site substitution in MCr₂O₄ nanoceramics on their properties is examined in this research. This study is an attempt to correlate the structural, morphological, and optical properties of M-site-modified chromites. The MCr₂O₄ nanoceramics-CuCr₂O₄, CoCr₂O₄, and NiCr₂O₄ were synthesized using a wet chemical sol–gel auto-combustion method, and all three samples were annealed for 4 h at 900 °C. X-ray diffraction analysis showed that the XRD patterns of CuCr₂O₄, CoCr₂O₄, and NiCr₂O₄ correspond to single-phase cubic crystal structures with the space group Fd-3m. Using the Scherrer equation, the crystallite sizes were found to be 9.86 nm, 6.73 nm, and 10.73 nm for CuCr₂O₄, CoCr₂O₄, and NiCr₂O₄, respectively. Other parameters, including crystal structure, micro-strain, lattice constant, unit cell volume, X-ray density, packing factor, and the stacking fault of the calcined powder samples, were determined from data acquired from the X-ray diffractometer. Energy dispersive X-ray spectroscopy (EDX) was employed to confirm the appropriate chromite elements in their expected stoichiometric proportions, removed from other impurities. The identification of the functional groups of the samples was performed using Fourier Transform Infrared Spectroscopy (FTIR). The absorption bands characteristic of tetrahedral and octahedral coordination compounds of the spinel structure are found between 450 and 750 cm⁻¹ for all three samples in the spectrum. From the UV-absorption spectra, and using Tauc’s plot, the energy bandgap values for CuCr₂O₄, CoCr₂O₄, and NiCr₂O₄ were measured to be 1.66 eV, 1.82 eV, and 2.01 eV, respectively. The dielectric properties of the chromites were studied using an LCR meter. Frequency-dependent dielectric properties, including Dielectric constant and Tangent loss, were calculated. These findings suggest the feasibility of the use of these synthesized chromites for optical devices and other optoelectronic applications. Full article

This work reports the design, fabrication, and validation of a modular ergonomic saddle for rehabilitation cycling, developed through a combined additive manufacturing approach. The saddle consists of a metallic support produced by Laser Powder Bed Fusion (LPBF) in AISI 316L stainless steel and a polymeric ergonomic covering fabricated via Selective Laser Sintering (SLS) using thermoplastic polyurethane (TPU). A preliminary material screening between TPU and polypropylene (PP) was conducted, with TPU selected for its superior elastic response, energy dissipation, and more favourable SLS processability, as confirmed by thermal analyses. A series of gyroid lattice configurations with varying cell sizes and wall thicknesses were designed and mechanically tested. Cyclic testing under both stress- and displacement-controlled conditions demonstrated that the configuration with 8 mm cell size and 0.3 mm wall thickness provided the best balance between compliance and stability, showing minimal permanent deformation after 10,000 cycles and stable force response under repeated displacements. Finite Element Method (FEM) simulations, parameterized using experimentally derived elastic and density data, correlated well with the mechanical results, correlated with the mechanical results, supporting comparative stiffness evaluation. Moreover, a cost model focused on the customizable TPU component confirmed the economic viability of the modular approach, where the metallic base remains a reusable standard. Finally, the modular saddle was fabricated and successfully mounted on a cycle ergometer, demonstrating functional feasibility. Full article

The high-efficiency and clean utilization of coal resources is a key strategy for new energy development, and converting coal into carbon materials offers a promising route to valorize bituminous coal. However, fabricating high-performance bituminous coal-derived carbon for sodium ion (Na⁺) insertion/extraction remains a major challenge, as it is difficult to regulate the carbon’s microstructural properties to match Na⁺ storage demands. Herein, we propose a molten salt-assisted carbonization strategy to prepare bituminous coal-derived hard carbon (HC) for use as a sodium-ion battery (SIB) anode material, and we focus on regulating the structure of carbon. The results show that as-prepared HC exhibits significantly enhanced electrochemical performance for Na⁺ storage when the molar ratio of NaCl to KCl is 1:1. The optimized material achieves a reversible capacity of 366.7 mAh g⁻¹ at the current density of 100 mA g⁻¹ after 60 cycles and retains 99% of its initial capacity after 500 cycles at a current density of 1 A g⁻¹. The main finding is that the lattice spacing can be regulated by tuning the composition of the molten salt, and anode performance is enhanced remarkably by changes in the HC structure. This work provides a feasible strategy for designing and preparing a bituminous coal-derived carbon anode material for use in the energy storage field. Full article

We present an analytical and numerical study of nonlinear wave localization in a one-dimensional rhombic (diamond) waveguide array that combines forward- and backward-propagating channels. This mixed-index configuration, realizable through Bragg-type couplers or corrugated waveguides, produces a tunable spectral gap and supports nonlinear self-localized states in both transmission and forbidden-band regimes. Starting from the full set of coupled-mode equations, we derive the effective evolution model, identify the role of coupling asymmetry and nonlinear coefficients, and obtain explicit soliton solutions using the method of multiple scales. The resulting envelopes satisfy a nonlinear Schrödinger equation with an effective nonlinear parameter $\theta$, which determines the conditions for soliton existence ($\theta >0$) for various combinations of focusing and defocusing nonlinearities. We distinguish solitons formed outside and inside the bandgap and analyze their dependence on the dispersion curvature and nonlinear response. Direct numerical simulations confirm the analytical predictions and reveal robust propagation and interactions of counter-propagating soliton modes. Order-of-magnitude estimates show that the predicted effects are accessible in realistic integrated photonic platforms. These results provide a unified theoretical framework for soliton formation in mixed-index lattices and suggest feasible routes for realizing controllable nonlinear localization in Bragg-type photonic structures. Full article

The Global Cement and Concrete Association (GCCA) estimated that by 2050, 36% industry-wide sustainable value will be created, which includes sequestering CO₂ into the cement and concrete industry to produce commercially feasible high-value products. Direct utilization of CO₂ in the cement and concrete industry, which utilizes natural and sustainable materials, is gaining momentum. Naturally occurring mixtures of hydro magnesite and huntite are important industrial minerals which, upon endothermic decomposition over a specific temperature range, will release water and CO₂. This unique chemistry has led to such mixtures being successfully utilized as fire retardants, replacing aluminum hydroxide or Alumina Tri-Hydrate (ATH). Despite the developed marketplace for magnesium-based fire-retardant products, there is little mention of CO₂ mineral carbonation methods, which attempt to recover and convert magnesium from natural seawater or industrial waste into oxides or carbonates as part of the carbon sequestration initiative. The hypothesis to be proven in this work states that if the process of seawater mineral carbonation is prematurely quenched, Mg²⁺ ionic species in seawater adsorbed on the calcite lattice formation will be trapped and therefore recovered in various oxidized forms, such as magnesium oxides, magnesium hydro magnesite, and magnesium carbonate precipitates. A novel method to recover magnesium Mg²⁺ ions from seawater was successfully explored and documented; as such, from an initial concentration of 1250 ppm Mg²⁺ in raw seawater, the average concentration of spent Mg²⁺ ions after the reaction was as low as 20 ppm. A very efficient near-total recovery of Mg²⁺ from the seawater into the solid precipitates was recorded. Subsequently, the process for continuous seawater mineral carbonation for the production of magnesium/brucite/huntite products was successfully proven and optimized to operate with a 30 s reaction time, a dynamic feedstock concentration, [CaO] at 1 gpl in seawater and a room temperature reaction temperature (30 °C), where the average yield of the fire-retardant magnesium-based compounds was 26% of the synthesized precipitates. Approximately 5000 g of the hydro magnesite materials was molded into a fire-retardant brick or concrete wall, which was subjected to an accredited fire performance and durability testing procedure BS476-22:1987. There were encouraging results from the fire resistance testing, where the fire-retardant material passed BS476-22:1987, with performance criteria such as physical integrity failure, the maximum allowable face temperature, and a minimum duration before failure, which was up to 104 min, evaluated. Full article