Search Results (1,836)

Hydrogen is increasingly seen as a viable energy carrier in the transition to low-carbon energy systems, mainly because of its high gravimetric energy density and the absence of carbon emissions at the point of use. In this context, producing hydrogen from biomass represents a practical and sustainable option, as it allows the use of renewable and waste resources while supporting circular economy principles. This work examines the main pathways for hydrogen production from biomass, considering both thermochemical and biochemical routes, with a focus on their energy performance and practical limitations. The analysis shows that thermochemical processes, particularly gasification, remain the most developed and scalable solutions for converting solid biomass into hydrogen-rich gas, although their performance depends strongly on feedstock properties, reactor design, and operating conditions. By comparison, biochemical processes such as dark fermentation and photofermentation are more suitable for wet biomass but are limited by lower hydrogen yields and issues related to process stability. From a thermal engineering standpoint, system performance is influenced by heat transfer constraints, the energy demand of endothermic reactions, and the efficiency of gas cleaning, while parameters such as temperature, steam-to-biomass ratio, and equivalence ratio play a key role in optimization. Advanced approaches, including catalytic and sorption-enhanced gasification, show potential for improving performance. Overall, efficient hydrogen production requires a system-level approach, as no single technology can be considered universally optimal. Full article

Piezoelectric semiconductor combines the unique properties of semiconducting characteristics and piezoelectric effect together, providing a universal methodology to modulate piezoelectric semiconductor device’s performance by simply introducing mechanical strain. To reveal the device physics beneath the piezoelectric modulation, in this work, a multiphysics COMSOL 6.0 simulation was employed to investigate the modulation of Si/GaN heterojunction PN diode characteristics via piezoelectric-induced interface polarization charges. The effects of charge polarity and density on forward recovery, reverse recovery, and irradiation responses were systematically analyzed. The results demonstrate that negative interface charges enhance carrier injection and accelerate device activation, whereas positive charges suppress overshoot and stabilize transient voltage behavior. During reverse recovery, negative charges shorten the storage delay and reduce the reverse peak current, improving the switching speed, whereas positive charges cause slower recovery. Under irradiation, the interface polarization charges modulate the photocurrent density by altering the depletion width and carrier collection efficiency; negative charges notably enhance the photocurrent in partially depleted devices. Furthermore, the influence of the polarization charges diminishes with increasing device length or doping concentration, as the built-in charge and electric field effects dominate. This study elucidates the physical mechanisms of piezoelectric charge control in Si/GaN heterojunctions and provides theoretical guidance for the design of high-speed, low-loss, and radiation-tunable power and optoelectronic devices. Full article

Organic-type solar cells containing an active layer of block copolymer donor PTB7-Fx (x = 0, 20, and 100), based on benzo [1,2-b:4,5-b’]dithiophene and variably fluorinated thieno [3,4-b]thiophene units, and fullerene acceptor [6,6]phenyl-C₇₁-methylbutyrate, were constructed. The active layer thin film of the solar cells was obtained from a dichlorobenzene solution at an established concentration via spin-coating of the donor–acceptor mixture in the presence of solvent additives such as 3% diiodooctane and 1% triethyl phosphate. Organic photovoltaic elements with normal device architecture were prepared on glass substrates using an indium tin oxide anode, a spin-coated hole transporting layer of poly(ethylene dioxythiophene):polystyrenesulfonate, the aforementioned active layer, followed by an electron transporting layer of zinc oxide nanoparticles, and finally a magnetron sputtered silver (Ag) top-electrode. The optical properties, thin film morphology, and the thickness of the active layers were investigated. Additionally, current density–voltage characteristics and impedance spectra of photovoltaic devices were measured. It was found that PTB7-Fx:PC₇₁BM-based solar cells processed in the presence of two types of solvent additives, diiodooctane and triethyl phosphate, with a sputtered Ag top-electrode display similar absorption and quantum efficiency spectra, as well as comparable current density–voltage characteristics and efficiencies to the same devices fabricated without additives. The diiodooctane solvent additive preferably dissolves the fullerene component and has a positive effect on fill factor enhancement, impedance spectra improvement, and amelioration in charge carrier transport and collection, whereas the triethyl phosphate solvent additive preferentially dissolves the copolymer donor and has a more pronounced impact on the refined morphology of the thin film active layers. Full article

This study investigates the enhancement of hydrogen production efficiency in water electrolysis through the application of external magnetic fields. A series of controlled experiments were conducted using four distinct electrode materials—stainless steel (SS), low-carbon steel (LCS), titanium (Ti), and platinum-plated titanium (Ti/Pt)—to identify the optimal configuration for maximizing gas output. The research evaluated the influence of electrolyte concentration (KOH), current density, and magnetic field intensity ranging from 0 to 1800 G. Our findings indicate that the application of a 200 G magnetic field leads to a notable 6% increase in the rate of gas production compared to non-magnetized conditions. Specifically, a magnetic field oriented parallel to the electrode plates outperformed a perpendicular orientation by approximately 5%, a phenomenon attributed to the Lorentz force facilitating ionic mass transfer and gas bubble detachment. Furthermore, the integration of ion-exchange and proton-exchange membranes (MC-3470 and N-117) effectively isolated the anodic and cathodic products, elevating hydrogen purity from 67.4% to approaching 100% without compromising electrolysis efficiency. These results demonstrate that the strategic coupling of moderate magnetic fields with optimized electrode configurations provides a promising pathway for improving the efficiency and cleanliness of hydrogen production, which is essential for its role as a sustainable energy carrier. Full article

As China’s first World Heritage Mixed Property site, Mount Tai enjoys international renown, with its historic buildings serving both as the central carriers of its cultural heritage and as significant tourism resources. Existing studies have predominantly emphasized the form, scale, and construction techniques of individual buildings or architectural complexes, while less attention has been given to the overall spatial pattern shaped by the interplay of natural and social environments and to the mechanisms underlying its formation. Taking the administrative area of Tai’an City as the study extent, this research selects 451 officially protected historic buildings, classified by period and type, and employs GIS-based spatial analysis and statistical methods to examine their spatiotemporal distribution patterns and influencing factors. The results indicate the following. (1) The temporal distribution exhibits an И-shaped fluctuation pattern, with ancient architecture and ancient sites together accounting for nearly 60% of the total and constituting the core resource categories. This distribution curve is shaped jointly by preservation conditions, social stability, and heritage designation preferences. (2) The spatial distribution displays a pronounced clustering pattern, with the kernel density core shifting over forty kilometers from southwest to northeast, generating an evolutionary trajectory from Dawen River basin agglomeration to Mount Tai mountain belt agglomeration. (3) The overall pattern is associated with both natural and anthropogenic factors. During the early stages, natural conditions such as hydrology and topography provided foundational constraints, whereas in later periods, human factors, including fengshan ritual culture, religious activities, economic development, and institutional governance, exhibit increasingly apparent associations with the distribution pattern. Based on these findings, this study proposes a strategic spatial framework comprising one cultural pilgrimage ring and four thematic corridors, which translates the spatial analytical results into planning implications for the regional integration of historic building resources, and discusses differentiated conservation strategies, thereby providing an analytical foundation and a reference pathway for the dissemination of Mount Tai culture and the sustainable development of heritage tourism. Full article

Background/Objectives: Calcium–phosphorus metabolism is critical for skeletal development in weaned piglets. This study evaluated the effects of dietary 25-hydroxyvitamin D₃ (25-OH-VD₃) in combination with phytase and probiotics on mineral metabolism, bone development, and related molecular mechanisms in weaned piglets. Methods: Sixty 28-day-old weaned piglets (7.1 ± 1.30 kg) were randomly assigned to four dietary treatments for 31 days (including 3 days of acclimation): CON (basal diet + 50 µg/kg 25-OH-VD₃), HI (CON + 50 mg/kg phytase), CY (CON +10 mg/kg probiotics), HICY (CON + 50 mg/kg phytase + 10 mg/kg probiotics). Apparent calcium digestibility, serum biochemical indices, bone mineral density (BMD), and mRNA and protein expression of calcium–phosphorus transport- and metabolism-related genes in jejunal mucosa and kidney were assessed. Results: Compared with CON, piglets in the HI, CY, and HICY groups showed higher apparent calcium digestibility (p < 0.05). Serum transforming growth factor-β was elevated in CY and HICY (p < 0.05). HI enhanced metatarsal and toe BMD (p < 0.05) and upregulated jejunal solute carrier family 34, member 2 (SLC34A2) and SLC34A3 mRNA expression (p < 0.05). In contrast, HICY reduced mRNA expression of transient receptor potential cation channel subfamily V member 6 and calcium-binding protein D28k, as well as of calcium-binding protein D9k and cytochrome P450 27B1 in the kidney (p < 0.05). Renal calcium-sensing receptor protein abundance increased in CY (p < 0.05). Conclusions: Supplementation of 25-OH-VD₃ with phytase and/or probiotics improved calcium utilization and modulated key transport pathways, contributing to enhanced bone development in weaned piglets. These findings highlight coordinated nutritional regulation of mineral metabolism during early post-weaning growth. Full article

Graphitic carbon nitride (CN) is a promising photocatalytic material, but its practical application is limited by small specific surface area, narrow light absorption range, and high photogenerated carrier recombination rate. To address these issues, this study synthesized boron-doped carbon nitride (BCN) and sulfuric acid-exfoliated boron-doped carbon nitride (BCND). X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results confirmed that boron was successfully doped into the CN skeleton via B-N bonds. Scanning electron microscopy (SEM) and N₂ adsorption–desorption (BET) characterizations showed that acid exfoliation significantly increased the specific surface area of BCND to 68.80 m²·g⁻¹, much higher than that of CN (9.54 m²·g⁻¹) and BCN (15.98 m²·g⁻¹). UV–visible diffuse reflectance spectroscopy (UV-Vis DRS) analysis revealed that BCND had the narrowest bandgap (2.59 eV) among the three materials, which enhanced its visible-light absorption efficiency. Photoelectrochemical tests demonstrated that BCND exhibited the smallest charge transfer resistance and the highest transient photocurrent density (eight times that of CN), indicating efficient separation of photogenerated electron–hole pairs. Photocatalytic water splitting experiments showed that BCND achieved the highest Hydrogen production rate of 792.34 μmol·g⁻¹·h⁻¹, which was about 4 times that of CN (158.41 μmol·g⁻¹·h⁻¹) and 1.36 times that of 2.5% BCN (584.30 μmol·g⁻¹·h⁻¹). Free-radical trapping experiments indicated that hydroxyl radicals (·OH) played a crucial promotional role in Hydrogen production, while superoxide anions (·O₂⁻) exerted an inhibitory effect. The enhanced performance of BCND was attributed to the synergistic effects of boron doping (narrowing bandgap) and acid exfoliation (increasing specific surface area). A possible photocatalytic Hydrogen production mechanism was proposed based on the experimental results. This study provides a feasible strategy for the structural modification and performance optimization of g-C₃N₄-based photocatalysts for water splitting. Full article

High-efficiency energy storage technologies have become particularly crucial with the ever-increasing demand for energy in recent years. Research on polymer nanocomposite dielectric materials has emerged as a prominent focus. Particularly, there is an urgent demand for the development of advanced dielectric film materials that exhibit superior energy storage performance over a wide temperature range. To this end, this study aims to investigate the effect of the molecular weight of reduced polyaniline (R-PANI) on the dielectric properties of all-organic composite films based on high-temperature-resistant polyetherimide (PEI). All-organic R-PANI/PEI composite films were fabricated by blending PEI matrix with R-PANI of varying molecular weights. Through combined density functional theory (DFT) calculations and experimental measurements, the blocking mechanism of R-PANI on charge carrier migration within the composite films was elucidated, showing a significant enhancement in the discharge energy density of PEI polymers while maintaining high charge–discharge efficiency. With charge–discharge efficiency maintained above 95%, R-PANI3/PEI achieved a discharge energy density of 2.36 J cm⁻³ at room temperature, nearly double that of pristine PEI (1.2 J cm⁻³). At 150 °C, the 1.0 wt% R-PANI3/PEI composite film retained a discharge energy density of 2.27 J cm⁻³ with a charge–discharge efficiency of 89.2%, outperforming pure PEI (1.1 J cm⁻³, 85.1%). These findings provide a new strategy for the design of all-organic composite dielectric films and demonstrate the potential of R-PANI in the application of high-performance capacitors and electrical energy storage. Full article

Climate change is intensifying drought stress in temperate forests, yet the mechanisms governing gradual versus threshold responses remain unclear, limiting adaptive management. This study tested whether tree morphological traits can help detect these response patterns and whether they vary with species identity, drought timescale, and stand structure. Using 2026 plot records (1022 larch, Larix principis-rupprechtii Mayr; 1004 Chinese pine, Pinus tabuliformis Carrière) from plantations across northern China, we combined random forest and generalized additive models to evaluate the height-to-diameter (H/D) ratio as a drought indicator. The H/D ratio outperforms height or diameter alone in detecting drought responses. Two distinct nonlinear strategies were identified: larch exhibited high sensitivity to spring drought with a threshold near SPEI ≈ −0.47, while Chinese pine showed resilience to short-term stress but nonlinear responses to cumulative drought (thresholds 0.07–0.12). These differences align with biomass allocation patterns, with Chinese pine maintaining lower H/D ratios. Stand structure significantly influenced responses, with strong Age × Density × Drought interactions (p < 0.001) highlighting vulnerability in young, dense stands. Overall, the H/D ratio provides a candidate early-warning indicator of drought vulnerability and may support species-specific monitoring and risk screening in young, high-density stands, although experimental validation is still needed. Full article

Rural settlements are significant carriers of rural production, living, and land use activities and are also significant subjects for researching regional socio-economic development and spatial structural changes. With regard to the unique topographical environment and transportation situation in the Qiongbei volcanic lava area, a settlement form with prominent topographical constraints and transportation orientation is created. This paper utilizes land use/land cover data from different periods, along with rural settlement expansion patch data, to quantitatively analyze the spatial patterns and expansion characteristics of rural settlements, as well as their influencing factors, from 1990 to 2025 using GIS spatial analysis, buffer gradient analysis (BGA), and multi-order adjacency index (MAI). The research results indicate the following: (1) The spatial pattern of rural settlement distribution in the study area is “peripheral agglomeration and core sparsity,” and the general expansion trend is “rapid in the early period and stable in the late period.” The settlement area expands from 37.21 km² in 1990 to 80.87 km² in 2025. (2) The evolutionary pattern of rural settlements in the study area changes from “core–peripheral extension” in the early period to a mixed “core stabilization and peripheral leapfrogging development” model in the later period. The new patches formed in the peripheral areas have obvious discrete features, such as varying land use patterns and differing population densities compared to the core areas. (3) The spatial correlation factors for rural settlement expansion in the study area exhibit stage differences and distinct spatial non-stationary characteristics. During the early period (1990–2008), with strict limitations imposed by the natural material environment, sunlight (interpretability of 0.367) and water systems (0.286) show significant spatial coherence, indicating the great adaptability of rural settlements to the material conditions of the landforms; during the later period (2008–2025), after the implementation of the rural revitalization strategy, the population density (0.135) and transport-related factors become the main spatial correlation factors. The GWR model also shows the percentage of positive and negative influences by influencing factors at each stage and their significant differences in space, proving that human activities break through in the limitations of natural topology in a discontinuous way. According to this research, “inefficient land use” should be understood in a dialectical manner in volcanic geomorphological areas, and spatial optimization should be achieved on the premise of respecting the physicality of volcanic landscapes and rural identity. The research conclusions have important guiding significance for the spatial resilience planning in tropical volcanic areas and traditional settlement culture preservation. Full article

Low charge-separation efficiency is a major factor limiting the photoelectric conversion performance of TiO₂. In this work, oxygen-vacancy-rich porous TiO₂ gel photocatalyst was successfully fabricated. The as-prepared material exhibits a three-dimensional interconnected hierarchical porous architecture with a specific surface area of 62.9 m² g⁻¹. EPR and XPS analyses confirmed the presence of Ti³⁺ defects and oxygen vacancies, which effectively increase the electron density and facilitate the separation and migration of photogenerated charge carriers. The results demonstrated excellent photocatalytic activity, with over 85% of RhB degraded within 50 min under light irradiation. In addition, its photocatalytic performance was further investigated by photocatalytic hydrogen evolution, and the hydrogen production rate reached 850.6 μmol·g⁻¹ h⁻¹. The enhanced photocatalytic performance can be mainly attributed to the synergistic effect of the hierarchical porous structure and oxygen vacancies. Specifically, the hierarchical porous structure improves mass transfer and provides abundant active sites, while oxygen vacancies modulate the electronic structure and promote charge separation, thereby significantly enhancing the catalytic activity. This work provides an effective strategy for improving the photoelectric conversion performance of TiO₂ and offers theoretical guidance as well as experimental support for the defect engineering and structural design of TiO₂-based photocatalytic materials. Full article

Huizhou Ancient Roads serve as a vital linear heritage carrier for inheriting Huizhou regional culture and supporting rural cultural revitalization. By analyzing the spatial pattern of Huizhou Vernacular Architecture and its correlation with ancient roads, this study provides a scientific basis for the systematic conservation, integrated development and sustainable utilization of Huizhou cultural heritage, as well as the promotion of cultural sustainability. Employing nearest neighbor index, kernel density analysis, and geographic detector, the results reveal that: (1) The spatial distribution of Huizhou Vernacular Architecture shows significant clustering and imbalance, forming a spatial pattern featuring “one main center, two cores, and extension along roads”, with the most intensive distribution in Shexian and Jixi counties. (2) Ancient road density, settlement density and freight volume are the dominant factors. Ancient road traffic and social culture are the most influential dimensions affecting the spatial distribution of Huizhou Vernacular Architecture. The formation and layout of Vernacular Architecture rely on multi-factor synergy, emphasizing multi-dimensional coupling. (3) Ancient road density and settlement density present the highest spatial variability, while elevation and slope show the lowest spatial variability. Mean elevation, mean slope, ancient road density, settlement density and cultural resources are all positively correlated with the distribution of Vernacular Architecture. Full article

CuIn₅Se₈ is reported as a remarkable copper-deficient layer that contains ordered vacancy compounds (OVCs) for high-efficiency chalcopyrite-based solar cells; however, the understanding of its carrier characteristics has remained limited. OVCs could naturally form on the surface of chalcopyrite absorber. In this study, the carrier dynamics characteristics of OVCs were investigated by constructing a junction consisting of chalcopyrite absorber and CdS buffer layer. At first, the band structure of CuIn₅Se₈ was studied to determine the bandgap properties. Then, thermodynamic stability, defect formation energy, defects and carrier concentration, defect transition energy level of CuIn₅Se₈ and its Cd doping state (caused by CdS) were comparatively studied. The results suggest that Cd doping has different effects on the defect and carrier characteristics of OVCs with various chemical potentials. However, the OVC always remains n-type under the whole thermodynamically stable region, with contribution from the hallow-level In_Cu donor defect. Finally, the OVC’s carrier dynamics characteristics were assessed using the collected defect and carrier data. It is indicated that the OVC layer may contribute to the formation of a p-n homojunction in solar cells. Under selenium-rich conditions, the OVC layer increases the carrier density on the n-type side of p-n junction nearly 30-fold, which helps reduce the difference in carrier density and minority current density between two sides of the p-n junction. The conversion efficiency of the solar cell with OVC shows a 7.25% improvement when compared to the control. The distinct behavior of OVCs may serve as a valuable reference for the creation or improvement of a related functional film layer or device. Full article

Electrohydrodynamic effects can significantly alter transport processes in reacting flows, even when the plasma is weakly ionized. However, predictive modeling of such plasma–flame interactions remains challenging due to the multiscale coupling among charge transport, fluid motion, and chemical kinetics. This study presents a charge-transport closure model to investigate electrohydrodynamic influences on laminar non-premixed flames. A two-dimensional computational framework in cylindrical coordinates is used to simulate plasma-assisted methane–air diffusion flames under weak electric-field conditions representative of practical combustion environments. To represent plasma–flow coupling in a computationally feasible yet physically consistent manner, a charge-transport formulation based on the drift–diffusion approximation is employed. The model solves transport equations for representative positive and negative charge carriers coupled with Poisson’s equation for the electric potential to obtain a self-consistent electric field. This formulation assumes a weakly ionized regime for low-temperature plasma-assisted combustion, in which neutral species dominate the mass and momentum transport, while ionization chemistry is simplified and charge transport primarily influences the flow through electrohydrodynamic body forces and Joule heating. Assuming a weak electric field, the steady flamelet model is applied, in which plasma effects primarily influence scalar transport and local thermal balance rather than inducing significant bulk ionization dynamics. The governing equations are discretized using a high-order compact finite-difference scheme that provides improved resolution of steep gradients in temperature, species concentration, and space-charge density near thin reaction zones. The canonical laminar flame model configuration was validated using the established laminar methane–air diffusion flame benchmark, and steady-state spatial profiles of key transport properties were evaluated. Two-dimensional analysis identified the discharge coupling location as an important factor. The application of discharge in the fuel-air mixing region leads to a clear restructuring of the flame. When the discharge is activated, electrohydrodynamic forcing and ion-driven momentum transfer produce a highly localized, columnar flame with sharp gradients and a confined reaction zone. Compared with the baseline case, the plasma-assisted flame localizes the OH-rich reaction zone, confines the high-temperature region into a narrow column, and enhances downstream H₂O formation. Full article

Hydrogen is a key energy carrier for the transition to renewable energy, but its storage remains a major challenge, mainly due to the energy requirements for its production and to its low volumetric energy density under ambient conditions. Clathrate hydrates have recently emerged as a promising medium for gas storage, yet their potential for hydrogen storage is still underexplored. This study presents a comprehensive bibliometric analysis of hydrogen storage research, focusing on clathrate hydrates. The analysis, based on publications indexed in Scopus over the past decades, reveals that research on gas hydrates is mature and interdisciplinary, encompassing hydrate formation, thermodynamics, and production from natural reservoirs. In contrast, hydrogen hydrates remain a marginal and emerging research area, characterized by limited scientific output and weak connections to dominant storage strategies such as metal hydrides, metal–organic frameworks, and adsorptive materials. The results highlight key research gaps, including a limited understanding of formation kinetics, thermodynamic stability under practical conditions, and challenges related to scalability and system integration. These findings suggest that targeted research efforts addressing these bottlenecks could support the development of hydrate-based systems as complementary solutions within the broader hydrogen storage landscape. Full article