Search Results (986)

The Changbai Mountain–Liaodong region is a crucial component of the global black soil belt in Northeast China and a significant national grain production base. However, like many high-latitude agricultural regions worldwide, it faces persistent challenges during the spring sowing period, including low soil temperatures and excessive moisture. Therefore, developing region-specific, effective methods of reducing soil moisture and increasing temperature while improving soil fertility is essential for improving agricultural productivity. To this aim, a field experiment was conducted with two factors: a main plot subjected to ridge tillage (RT) and flat tillage (FT) and subplots with biochar (BC) and straw (ST) amendments. A subplot with no amendment (CK) was used as a control. During maize growth, the daily soil temperature and moisture were monitored, and the soil water evaporation rates and physical structure, as well as the maize yield performance, were evaluated. The results showed that biochar and straw application significantly decreased the soil monthly water content by 1.69–2.22% (p < 0.05) in the surface soil layer (0–15 cm) from May to June, with a more pronounced effect under RT. In contrast, biochar application increased soil moisture and water storage from July to September, indicating that the influence of biochar on soil moisture depends on time and field aging processes. Biochar amendment raised the soil maximum temperature by 0.32–0.79 °C in the top 0–15 cm layer, while straw incorporation decreased the minimum soil temperature by 0.11–0.52 °C. The increase in soil temperature was primarily due to the biochar’s darker color, which facilitated solar radiation absorption, while the decrease in soil temperature was caused by the “Wind Leakage Effect” induced by the large particle size of the straw. Biochar and straw incorporation effectively enhanced maize dry matter accumulation by an average of 15.8% and 8.2%, respectively, and grain yield by 13.0% and 7.8%, respectively. Correlation analysis indicates that these increments are primarily due to enhanced soil moisture and available N content during the middle to late stages of maize growth. Therefore, the integration of straw and biochar with high-ridge cultivation is an effective strategy for excessive moisture reduction and warming in spring soil and it also contributes positively to maize yield. Full article

This work presents the design and characterization of a thermoregulated, bandwidth-enhanced TEM cell system optimized for bioelectromagnetic experiments on biological cells, with a focus on bioluminescence resonance energy transfer investigations at 700 MHz and 3.5 GHz. Bandwidth improvement, achieved through geometric modifications and optimized connector transitions, resulted in reduced return and insertion losses and improved field uniformity, particularly in the 2.5–6 GHz range. Numerical simulations showed homogeneous electric field and normalized specific absorption rate (SAR) distributions (~1 W/kg) at 700 MHz. At 3.5 GHz, the improved TEM cell provided the most uniform exposure of the biological sample with SAR values of 15 W/kg and 10.5 W/kg, for the bulk and surface (bottom layer), respectively. Experimental SAR measurements using a ~1 mm³ fluoro-optic probe agreed well with simulations. To counteract RF-induced heating, the system incorporated active thermoregulation at 37 °C. At 3.5 GHz and 20 W input power, a 1.5 °C rise over 120 s was effectively mitigated using water-circulation cooling. This work provides a controlled and reliable setup for future studies on the interaction of 5G-band electromagnetic fields with biological systems. Full article

The expansion of fifth-generation (5G) wireless networks has increased environmental exposure to mid-band and millimeter-wave radiofrequency electromagnetic fields (RF-EMF), but their molecular effects on male reproductive tissues remain insufficiently understood. This study evaluated whether repeated exposure to 3.5 GHz and 24 GHz RF-EMF alters testicular stress-associated molecular responses by integrating electromagnetic dosimetry with an in vivo rat model. Whole-body specific absorption rate (SAR) and 10 g peak SAR were estimated using a rat voxel model and scaled to the 20 cm antenna-to-cage geometry used during exposure. Thirty-six adult male Sprague Dawley rats were allocated to sham, 3.5 GHz, or 24 GHz groups and exposed for 1 h/day or 7 h/day over 60 days. Testes were examined histologically and assessed for HSP27, HSP70, and HSP90 protein expression. SAR values were low overall, although absorption was higher at 3.5 GHz than at 24 GHz. Histological evaluation showed preserved seminiferous tubule architecture without consistent structural injury. In contrast, molecular analysis demonstrated frequency- and duration-dependent modulation of heat shock proteins, including early HSP70 downregulation at both frequencies, followed by HSP90 upregulation at 3.5 GHz and HSP27 upregulation at 24 GHz. These findings indicate that low-level 5G-relevant RF-EMF exposure can modify molecular stress responses in testicular tissue even in the absence of overt histological damage. Full article

Polyolefin bonding technologies with metal foils are extensively employed in various sectors, particularly in automotive, electronics, and aerospace industries. This research examined the innovative electromagnetic joining of polyolefins to aluminum by evaluating the behavior of hot-melt adhesives derived from polyolefins containing metallic particles. The study aimed at establishing the specific absorption rate (SAR, expressed in W/kg) via electromagnetic simulation using CST Studio Suite software. It was observed that, regardless of particle size, Al was the most efficient particle, while the distribution of particles has a negligible impact on Total SAR values. The most significant beneficial effect of the inserts on the absorption capacity of the hot-melt material is primarily observed with a particle size of 1 μm. When connecting polyolefins to aluminum, the power loss density and SAR values exceed those for bonding polyolefins to polyolefins by at least 10 times, owing to aluminum’s conductive properties, which influence the absorption of additional energy in the hot melt mass, likely due to the Salisbury screen effect generated by the bonding arrangement. For hot melts made from polyethylene, a higher frequency of 5.8 GHz is suggested, which is a newly approved frequency used in advanced industrial applications. This positively impacts the effectiveness and viability of the bonding process of polyolefins to aluminum, resulting in reduced exposure times and/or decreased microwave exposure power. It was observed that the hot melts derived from HDPE and PP yielded greater SAR values. Conversely, the SAR values increase when aluminum is attached to HDPE. As a result, the strongest bond of polyolefins to Al occurs when connecting HDPE to Al using HDPE-based hot melts. The proposed simulation methodology may offer considerable improvement in evaluating the efficacy of bonding technology for dissimilar materials subjected to electromagnetic energy Full article

Gypsum-based fire protection relies on thermally activated dehydration, where chemically bound water is released and evaporated, thereby providing an endothermic heat sink that delays heat penetration through assemblies. In parallel, inorganic hydrated salts are increasingly used as flame-retardant additives in gypsum-based systems to enhance heat absorption over specific temperature ranges. Fire simulation tools and performance-based fire engineering approaches require reliable kinetic data and reaction enthalpies that can be implemented as coupled thermal–chemical source terms. However, additive-specific kinetic datasets remain limited, particularly under restricted vapor exchange conditions representative of porous construction materials. This work investigates the thermal decomposition behavior and dehydration kinetics of Aluminum Trihydrate (Al(OH)₃, ATH), Magnesium Hydroxide (Mg(OH)₂, MDH), Calcium Aluminate Sulfate (3CaO·Al₂O₃·3CaSO₄·32H₂O, CAS), and Magnesium Sulfate Heptahydrate (MgSO₄·7H₂O, ESM) with emphasis on vapor-restricted conditions representative of confined porous systems. Differential scanning calorimetry (DSC) experiments were conducted at three heating rates (2, 10, and 20 K/min for MDH, CAS and ESM and 20, 40 and 60 K/min for GB-ATH) up to 600 °C using pinhole crucibles to simulate autogenous vapor pressure. The thermal analysis indicates that ATH and MDH exhibit predominantly single-step dehydration behavior, while ESM shows a complex multi-step mechanism. Although CAS presents a single dominant thermal peak in the DSC signal, the isoconversional analysis reveals a multi-stage reaction behavior, demonstrating that peak-based interpretation alone may be insufficient for such systems. Kinetic parameters were determined using both model-free (Starink) and model-fitting approaches in accordance with the recommendations of the Kinetics Committee of the International Confederation for Thermal Analysis and Calorimetry (ICTAC). All reactions were consistently described using the Avrami–Erofeev model as an effective phenomenological representation of the conversion behavior. The extracted kinetic triplets were validated through numerical simulations, showing good agreement with experimental conversion and reaction rate data. The resulting kinetic parameters and dehydration enthalpies provide a physically consistent dataset for the description of dehydration processes under restricted vapor exchange. These results support the development of thermochemical models for gypsum-based systems; however, their transferability to full-scale assemblies remains subject to validation under coupled heat- and mass-transfer conditions. Full article

This work presents a mechanistic modeling approach for simulating methane emissions from triethylene glycol (TEG) dehydrators used in oil & gas (O&G) operations. The model was developed as a modular component of the Mechanistic Air Emissions Simulator (MAES) tool, incorporating species-specific absorption and emission dynamics through two-level, second-order polynomial regression (PR) models trained on ProMax simulation data: (1) species-level regression models that track the transfer rates of individual gas species within the dehydrator unit streams, and (2) outlet flow stream regression models that predict the fraction of inlet gas distributed among the outlet streams of the dehydrator unit. These behaviors were characterized over a range of glycol circulation ratios, wet gas pressures, and temperatures. The model was validated using root mean square error (RMSE) analysis. The species-level PR achieved low root mean square error (RMSE) values (<0.03) for light hydrocarbon species across all dehydrator components, ranging from 0.0009 for methane to 0.029 for normal pentane. Similarly, the outlet-level PR yielded RMSE values below 0.002 for the dry gas fraction, 0.001 for the flash tank fraction, and 0.002 for the still vent fraction, demonstrating strong agreement between predicted and reference ProMax values. When deployed at field facilities, the model significantly improved MAES-simulated dehydrator emissions, revealing that gas-assisted glycol pump emissions are the dominant contributors to both dehydrator-level and site-level methane emissions under uncontrolled conditions. Further analysis of the 154 dehydrator units reported by operators under the AMI 2024 project showed that 54 units (31%) used gas-driven glycol pumps, of which 6 units (11%) operated with uncontrolled flash tanks, and 22 units (40.7%) were identified as potentially oversized. Of the six dehydrator units with uncontrolled gas-assisted pumps, pump emissions accounted for 90.25% of total dehydrator emissions and 63.10% of total site-level emissions. These findings highlight substantial opportunities for emissions mitigation through equipment upgrades. Full article

Bamboo is widely available and renewable. Using bamboo blocks to partially replace coarse aggregates in the production of concrete solid bricks shows promising application prospects in areas such as nonload-bearing wall materials. However, as a natural biomass material, bamboo squares have disadvantages such as susceptibility to decay, water absorption, swelling, and drying shrinkage, necessitating modification when used as concrete coarse aggregate. This study subjected raw bamboo squares to high-temperature carbonization. The compressive performance of concrete made with these carbonized bamboo squares was first tested and compared with concrete containing raw bamboo squares. Subsequently, both raw and carbonized bamboo squares were modified using conventional methods: polyvinyl alcohol (PVA) treatment, epoxy mortar (EM) treatment, epoxy resin (EPR) treatment, water glass (WG) treatment, and glutinous rice glue treatment. Modified bamboo block concrete specimens were prepared, and their compressive strengths were tested and compared. The results indicated that the compressive mechanical performance of carbonized bamboo block concrete consistently outperformed that of raw bamboo block concrete across all substitution rates. Specifically, the optimal modification method—using epoxy mortar (EM) encapsulation—significantly enhanced the mechanical properties. At a high volumetric replacement rate of 30%, the EM-modified carbonized bamboo concrete achieved a compressive strength of 27.79 MPa, which is 15.1% higher than that of identically treated raw bamboo concrete and far exceeds the standard MU7.5 grade requirements. These quantitative findings provide a solid experimental and theoretical basis for the high-value application of bamboo squares in sustainable concrete solid bricks. Full article

Post-combustion amine scrubbing using monoethanolamine (MEA) remains a leading carbon capture technology, yet its deployment is constrained by high regeneration energy requirements and the computational expense of rigorous process simulation. This study presents an integrated framework coupling high-fidelity rate-based process simulation with explainable machine learning to systematically characterize a ten-dimensional operating space for MEA-based CO₂ absorption. Latin hypercube sampling generated 10,000 steady-state cases, and five regression architectures were benchmarked under identical protocols. A neural network achieved the highest accuracy (R² = 0.9729, RMSE = 1.43%), while XGBoost was selected as the operational surrogate due to its robust computational efficiency (1.5 ms inference latency) and native compatibility with exact Shapley value decomposition. SHAP analysis identified liquid-to-gas ratio as the dominant efficiency determinant, contributing 46.6% of total predictive importance, followed by inlet temperature and MEA concentration, with these three parameters collectively explaining 85% of efficiency variation and establishing a compact control hierarchy suitable for reduced-order control architectures. Bivariate interaction analysis located a high-efficiency operating region, while sensitivity analysis confirmed the strong influence of inlet temperature across the operating envelope. Pareto optimization via NSGA-II generated tiered operational guidelines spanning the 85% to 98% capture efficiency range, quantifying a 39% specific regeneration duty penalty (3.1 to 4.3 MJ/kg CO₂) for pursuing maximum versus baseline capture targets. The framework demonstrates how explainable machine learning converts opaque process simulations into actionable engineering knowledge, providing a transparent and computationally efficient basis for design optimization and digital twin deployment in post-combustion carbon capture systems. Full article

Background/Objectives: MRI-guided neurovascular interventions could benefit from lower-field systems due to reduced magnetic and radiofrequency hazards. However, safety and practical visibility of commonly used neurointerventional devices at 0.55 T remain insufficiently characterized. We evaluated magnetic field interactions, RF-induced heating, and qualitative device visibility in 11 commercially available and commonly used neurovascular devices on a 0.55 T MRI system. Methods: Eleven devices, including stent retrievers, guidewires, catheters, and one embolization implant, were tested at 0.55 T. Magnetostatic interactions were quantified using the American Society for Testing and Materials (ASTM)-guided deflection methods for translational force (ASTM-F2052) and a two-string suspension apparatus for torque (adapted from Stoianovici et al.). RF-induced heating was measured in an in vitro perfused cerebral vessel phantom using a 15 min high-specific absorption rate spin echo sequence under static and flow conditions. Qualitative device visibility was assessed using a turbo spin echo (TSE) and balanced steady-state free precession (bSSFP) imaging on each device individually. Results: Eight of eleven devices passed the translational force test, while three devices (D, E, and G), containing significant ferromagnetic components, failed with deflection angles > 45°. Eight devices passed torque testing, remaining below the critical threshold in all rotation positions; three devices (D, G, and J) failed by exceeding the 54° criterion, including one guidewire and two devices with braided/coiled metallic structures. Under static conditions, RF-induced heating ranged from negligible to 10.4 °C (maximum in device D) and generally decreased under flow; in the flow configuration, temperature rise remained below 2 °C for 6/11 devices. Qualitative imaging performance differed by sequence, with bSSFP enabling improved delineation of device structure (best for devices A, C, and H), whereas devices D, E, F, and J produced extensive signal voids that precluded reliable visualization in both sequences. Overall, three devices satisfied all safety criteria while remaining clearly visible under MRI. Conclusions: Devices that pass safety thresholds at 0.55 T can serve as candidates for further sequence optimization and preclinical workflow development, enabling the design of low-SAR, device-compatible imaging protocols tailored for neurointerventional workflows. These results provide key safety data supporting the feasibility of MR-guided neurovascular procedures at 0.55 T. Full article

This study examined how human resource management (HRM) training and development practices contribute to strengthening knowledge absorptive and protective capacities within South African state-owned enterprises (SOEs). Using an exploratory mixed-methods approach, this research was conducted in two phases. Firstly, 20 HR managers were interviewed, and annual reports from nine SOEs were reviewed. Thematic analysis, supported by Atlas.ti, revealed key insights that informed the design of a survey used in the second phase. In the second phase, the survey was administered to 585 randomly selected employees across three SOEs, achieving a 25% response rate. Data analysis carried out with Statistical Analysis Software (SAS) version 8.4 showed strong reliability, with a Cronbach’s alpha of 0.94. Findings indicate that training and development initiatives play a significant role in building absorptive capacity as they enhance knowledge acquisition and the ability to integrate new skills. These practices also reinforced employees’ tacit knowledge base, particularly through job-specific training and skills development. However, whilst HRM practices were effective in knowledge absorption, they were less successful in safeguarding and protecting critical tacit knowledge against potential loss. This study highlights the dual challenge facing SOEs: advancing employees’ capacity to absorb knowledge whilst also developing stronger mechanisms to protect valuable expertise. Full article

Ultra-high-field (UHF) magnetic resonance imaging, defined as imaging at field strengths of 7 Tesla (7T) and above, represents a frontier technology in neuroimaging with emerging applications in prenatal brain research. This narrative review examines the current evidence on the potential benefits of UHF-MRI for investigating embryonic and fetal brain development. Through analysis of 97 studies identified across multiple databases, we find that UHF-MRI offers substantial advantages in spatial resolution, tissue contrast, and anatomical detail compared to conventional clinical field strengths (1.5T and 3T). The primary applications to date have been in ex vivo imaging of post-mortem fetal specimens and preclinical animal models, where UHF-MRI has enabled unprecedented visualization of laminar cortical organization, early sulcation patterns, microstructural development, and subtle anatomical features critical for understanding normal and abnormal neurodevelopment. Key benefits include enhanced delineation of transient developmental zones, improved characterization of cortical folding, superior detection of subtle malformations, and the ability to create high-resolution three-dimensional atlases of fetal brain development. However, significant technical and safety challenges currently limit in utero human applications, including concerns about specific absorption rate, acoustic noise, and fetal motion artifacts. This review identifies critical knowledge gaps and future directions for translating UHF-MRI technology to clinical prenatal diagnostics. Full article

A dual-band flexible wearable MIMO antenna with two operating modes, namely low-frequency narrowband and high-frequency broadband, is proposed and investigated in this paper. The antenna is based on a polyimide (PI) flexible printed circuit (FPC) substrate and has a compact size (90 mm × 40 mm × 0.1 mm), enabling easy integration into helmet-mounted devices. The antenna elements are fed by a coplanar waveguide (CPW) and integrated with a ground decoupling structure, achieving an isolation of at least 23.4 dB between the two ports across the entire operating frequency band. In addition, the impedance-matching characteristics of the antenna under bending conditions and the Specific Absorption Rate (SAR) of this MIMO antenna in a 1 g human-tissue model at 3.7 GHz and 4.6 GHz were evaluated. The results indicate that the antenna’s key electromagnetic performance remains relatively stable under bending conditions, and the SAR values comply with international limit requirements, verifying its feasibility for application in head-worn terminals. With an impedance bandwidth of −10 dB, this antenna achieves dual-band coverage at 3.42–3.84 GHz (relative bandwidth of 11.6%) and 4.37–7.80 GHz (relative bandwidth of 56.4%), effectively meeting the requirements of 5G/6G communication frequency bands. Full article

Thermally induced self-healing technology is regarded as an effective approach to mitigating the frequent occurrence of asphalt pavement distresses. Its efficiency, however, is highly dependent on the thermal conductivity of asphalt mixtures, which conventional aggregates can hardly satisfy. Meanwhile, high-titanium heavy slag (HTHS), an industrial solid waste rich in TiO₂, has been stockpiled in large quantities, and its large-scale resource utilization remains a critical challenge. Against this background, HTHS was employed in this study to replace limestone at equal mass ratios for the preparation of seven asphalt mastics (replacement rates of 0%, 20%, 40%, 60%, 80%, 100%, and neat asphalt) and four types of asphalt mixtures differentiated by coarse and fine aggregate compositions. The results indicate that with increasing HTHS content, the proportion of structural asphalt in the mastic increased markedly, leading to significant improvements in temperature susceptibility, high-temperature stability, and rutting resistance. Compared with the 100% limestone system, the penetration index (PI) of the 100% HTHS mastic increased by 8.4%, the softening point rose by 18.0%, and the rutting resistance factor at five temperatures from 46 °C to 70 °C increased by 21.8%, 56.8%, 79.2%, 171.7%, and 169.6%, respectively. Although low-temperature ductility decreased by 21.3% due to the reduction in free asphalt, it remained within acceptable limits. Regarding asphalt mixture performance, both high-temperature stability and low-temperature cracking resistance improved progressively with increasing HTHS replacement, showing increases of 75.56% and 11.75%, respectively, at full replacement. Water stability decreased by approximately 9% owing to the porous and water-absorptive nature of the slag, yet still satisfied specification requirements. In addition, the incorporation of HTHS significantly enhanced the thermal conductivity of the system, with increases of 0.125 W/(m·K) for asphalt mastics and 0.666 W/(m·K) for asphalt mixtures, corresponding to improvements of 33.7% and 32.2%, respectively. This study confirms that HTHS can serve as a viable asphalt pavement material capable of meeting the thermal conductivity requirements of thermally induced self-healing technology, while simultaneously providing a promising pathway for its large-scale resource utilization. Full article

This work presents the design of a compact, wideband circular microstrip patch antenna for microwave imaging-based brain tumor detection. The main contribution is the development of a compact antenna structure incorporating enhanced ground-plane slot modifications, which significantly improves impedance bandwidth while maintaining a small electrical size, making it highly suitable for medical imaging systems. In addition, the study integrates antenna design, safety evaluation, and microwave imaging analysis within a unified framework to assess tumor localization feasibility using a realistic head model in CST Microwave Studio. The proposed antenna is fabricated on an FR-4 substrate with dimensions of 37 × 54.5 × 1.6 mm³, corresponding to an electrical size of 0.176λ × 0.260λ × 0.0076λ at the lowest operating frequency of 1.43 GHz. Ground-plane slot enhancements are introduced to achieve wideband performance, resulting in an impedance bandwidth from 1.43 to 4 GHz and a fractional bandwidth of 94.7%. The antenna exhibits a maximum realized gain of 3.7 dB. To evaluate its suitability for medical applications, specific absorption rate (SAR) analysis is performed using a realistic human head model at multiple antenna positions and at 1.5, 2.1, 2.5, 3.3, and 3.9 GHz frequencies. The computed SAR values range from 0.109 to 1.56 W/kg averaged over 10 g of tissue, satisfying the IEEE C95.1 safety guideline limit of 2 W/kg. For tumor detection assessment, time-domain simulations are conducted in CST Microwave Studio using a monostatic radar configuration, where the antenna operates as both transmitter and receiver at twelve angular positions around the head with 30° increments. The collected scattered signals are processed using the Delay-and-Sum (DAS) beamforming algorithm to reconstruct dielectric contrast maps and localize the tumor. It should be noted that the tumor-imaging demonstrations presented in this work are based on numerical simulations, while experimental validation is limited to the characterization of the fabricated antenna. Nevertheless, the findings indicate that the proposed antenna is a promising candidate for noninvasive, low-cost microwave brain tumor imaging applications. Full article

Globalisation, accompanied by the rapid advancement of digital technologies, has become the bedrock of contemporary economies. However, the global digital divide has hindered many economies from enjoying the benefits of enhanced digitalisation. This study addresses the question: to what extent is there evidence of digital convergence or divergence among global economies, and what specific patterns of club clustering exist within the African continent? Employing a quantitative research design with secondary panel data from 123 countries (38 African), the study applies the Phillips and Sul convergence and club clustering algorithm to analyse digitalisation trends. The findings reveal that African countries exhibit significantly stronger within-club convergence dynamics than broader developing country groups, with Africa’s adjustment speed (σ = 2.5624) exceeding the Global South average (σ = 0.8394) by more than threefold. This indicates that African nations are following a similar ICT development trajectory and catching up with other global regions at an accelerated rate. However, the study identifies substantial digital inequality within Africa itself, as countries fail to converge to a single steady state, instead forming distinct convergence clubs. These results underscore that digitalisation follows a systematic and continuous process determined by both technological advancement and countries’ absorptive capacity to adopt these technologies. Full article