Search Results (326)

Aluminum–hydrogen compounds have drawn considerable interest for applications in solid-state hydrogen storage. The structural, hydrogen storage, electronic, mechanical, phonon, and thermodynamic properties of XAl₂H₂ (X = Ca, Sr, Sc, Y) hydrides are investigated using density functional theory. These hydrides exhibit negative formation energies in the hexagonal phase, indicating their thermodynamic stability. The gravimetric hydrogen storage capacities of CaAl₂H₂, SrAl₂H₂, ScAl₂H₂, and YAl₂H₂ are calculated to be 1.41 wt%, 0.94 wt%, 1.34 wt%, and 0.93 wt%, respectively. Analysis of the electronic density of states reveals metallic characteristics. Furthermore, the calculated elastic constants satisfy the Born stability criteria, confirming their mechanical stability. Additionally, through phonon spectra analysis, dynamical stability is verified for CaAl₂H₂ and SrAl₂H₂ but not for ScAl₂H₂ and YAl₂H₂. Finally, we present temperature-dependent thermodynamic properties. This research reveals that XAl₂H₂ (X = Ca, Sr, Sc, Y) materials represent promising candidates for solid-state hydrogen storage, providing a theoretical foundation for further studies on XAl₂H₂ systems. Full article

Hydrogen is widely recognized as a key enabler of the clean energy transition, but the lack of safe, efficient, and scalable storage technologies continues to hinder its broad deployment. Conventional hydrogen storage approaches, such as compressed hydrogen storage, cryo-compressed hydrogen storage, and liquid hydrogen storage, face limitations, including high energy consumption, elevated cost, weight, and safety concerns. In contrast, solid-state hydrogen storage using carbon-based adsorbents has gained growing attention due to their chemical tunability, low cost, and potential for modular integration into energy systems. This review provides a comprehensive evaluation of hydrogen storage using carbon-based materials, covering fundamental adsorption mechanisms, classical materials, emerging architectures, and recent advances in computationally AI-guided material design. We first discuss the physicochemical principles driving hydrogen physisorption, chemisorption, Kubas interaction, and spillover effects on carbon surfaces. Classical adsorbents, such as activated carbon, carbon nanotubes, graphene, carbon dots, and biochar, are evaluated in terms of pore structure, dopant effects, and uptake capacity. The review then highlights recent progress in advanced carbon architectures, such as MXenes, three-dimensional architectures, and 3D-printed carbon platforms, with emphasis on their gravimetric and volumetric performance under practical conditions. Importantly, this review introduces a forward-looking perspective on the application of artificial intelligence and machine learning tools for data-driven sorbent design. These methods enable high-throughput screening of materials, prediction of performance metrics, and identification of structure–property relationships. By combining experimental insights with computational advances, carbon-based hydrogen storage platforms are expected to play a pivotal role in the next generation of energy storage systems. The paper concludes with a discussion on remaining challenges, utilization scenarios, and the need for interdisciplinary efforts to realize practical applications. Full article

Advancements in structural engineering are expected to enhance the wide-range commercial application of lithium-ion batteries by enabling the implementation of thicker cathode materials. Increasing the thickness of these cathodes can yield significant increasements in gravimetric energy density while concurrently lowering manufacturing costs. These improvements are pivotal to the successful commercial deployment of sustainable transport systems. However, several substantial barriers persist in the adoption of such microstructures, including performance degradation, manufacturing complexities, and scalability concerns, all of which remain open areas of investigation. This review delves into the obstacles associated with current modifying techniques in thick cathodes and explores the potential opportunities to develop more robust and thicker cathodes, while ensuring long-term performance and scalability. Finally, we provide suggestions on the future directions of thick cathodes to promote their large-scale application. Full article

This study was conducted in the northeast of the Tadla plain, within the Beni Mellal-Khenifra region of Morocco. The primary objective is to elucidate the geometric and hydrogeological characteristics of this aquifer by analyzing and interpreting data from deep boreholes as well as gravimetric and electrical measurements using GIS analysis. First, the regional gradient was established. Then, the initial data were extracted. Subsequently, based on the extracted data, a gravity map was created. The investigation of the Bouguer anomaly’s gravity map exposes the presence of a regional gradient, with values varying from −100 mGal in the South to −30 mGal in the North of the area. These Bouguer anomalies often correlate with exposed basement rock areas and variations in the thickness of sedimentary layers across the study area. The analysis of existing electrical survey and deep drilling data confirms the results of the gravimetry survey after applying different techniques such as horizontal gradient and upward extension on the gravimetric map. The findings enabled us to create a structural map highlighting the fault systems responsible for shaping the study area’s structure. The elaborated structural map serves as an indispensable geotectonic reference, facilitating the delineation of subsurface heterogeneities and providing a robust foundation for further hydrogeological assessments in the Tadla Plain. Full article

MXenes, a family of two-dimensional carbide and nitride nanomaterials, have demonstrated significant promise across various technological domains, particularly in energy storage applications. This review critically examines scalable synthesis techniques for MXenes and their potential integration into next-generation rechargeable battery systems. We highlight both top-down and emerging bottom-up approaches, exploring their respective efficiencies, environmental impacts, and industrial feasibility. The paper further discusses the electrochemical behavior of MXenes in lithium-ion, sodium-ion, and aluminum-ion batteries, as well as their multifunctional roles in solid-state batteries—including as electrodes, additives, and solid electrolytes. Special emphasis is placed on surface functionalization, interlayer engineering, and ion transport properties. We also compare MXenes with conventional graphite anodes, analyzing their gravimetric and volumetric performance potential. Finally, challenges such as diffusion kinetics, power density limitations, and scalability are addressed, providing a comprehensive outlook on the future of MXenes in sustainable energy storage technologies. Full article

This paper proposes a mathematical description of nitriding atmospheres obtained from a one-component ammonia ingoing atmosphere and a two-component ammonia inlet nitrogen-diluted atmosphere. The Fe-N phase equilibrium diagrams of the nitriding atmosphere in the hydrogen content-temperature (Q-T) system for selected NH₃/N₂ atmosphere compositions are presented. The nitriding atmosphere obtained with different degrees of nitrogen dilution of the ingoing atmosphere was characterized. It has been shown that in processes carried out in nitriding atmospheres obtained from a two-component atmosphere with nitrogen, there is no direct relationship between the value of the nitrogen potential and the degree of dilution of the ingoing atmosphere with nitrogen. It has been shown analytically and confirmed experimentally that with changes in the degree of dilution of ammonia with nitrogen, the hydrogen content of the nitriding atmosphere and, consequently, the nitrogen availability of the nitriding atmosphere change. Using the example of nitriding AISI 52100 steel, it has been experimentally demonstrated that the change in nitrogen availability, caused by a change in the degree of dilution of the ingoing atmosphere with nitrogen, is not accompanied by a change in the value of the nitrogen potential. It has also been shown that the change in the nitrogen availability of the nitriding atmosphere, induced by the change in the composition of the aNH₃/bN₂ ingoing atmosphere, affects the kinetics of nitrogen mass gain in the nitrided layer and the distribution of nitrogen mass between the iron nitride layer and the solution zone. It has also been shown that with the change in nitrogen availability, what changes in addition to the thickness of the iron nitride layer is also the phase composition of the layer. Using gravimetric tests, the mass of nitrogen in the iron nitride layer and the solution zone has been determined. To describe the equilibrium between the NH₃/H₂ atmosphere and nitrogen in the different iron phases, a modified Lehrer diagram in the coordinate system of temperature and hydrogen content in the nitriding atmospheres (T-Q) has been proposed. Full article

The objective of this study was to evaluate the effects of different water levels on yield, morphological, and quality parameters, as well as the crop water stress index (CWSI), for pepper plants under a high tunnel greenhouse in a semi-arid region. For this purpose, the irrigation schedule used in this study includes 120%, 100%, 80%, and 60% (I120, I100, I80, and I60) of evaporation monitored gravimetrically. In this study, increasing irrigation levels (I100 and I120) resulted in increased stem diameter, plant height, fruit number, leaf number, and leaf area values. However, these values decreased as the water level dropped (I60 and I80). At the same time, increased irrigation resulted in improvements in fruit width, length, and weight, as well as a decrease in TSS values. While total yield and marketable yield values increased at the I120 water level, TWUE and MWUE were the highest at the I100 water level. I80 and I120 water levels were statistically in the same group. It was found that the application of I100 water level in the high tunnel greenhouse is the appropriate irrigation level in terms of morphology and quality parameters. However, in places with water scarcity, a moderate water deficit (I80) can be adopted instead of full (I100) or excessive irrigation (I120) in pepper cultivation in terms of water conservation. The experimental results reveal significant correlations between the parameters of green pepper yield and the CWSI. Therefore, a mean CWSI of 0.16 is recommended for irrigation level I100 for higher-quality yields. A mean CWSI of 0.22 is recommended for irrigation level I80 in areas where water is scarce. While increasing the CWSI values decreased the values of crop water consumption, leaf area index, total yield, marketable yield, total water use efficiency, and marketable water use efficiency, decreasing the CWSI increased these values. This study concluded that the CWSI can be effectively utilised in irrigation time planning under semi-arid climate conditions. With the advancement of technology, determining the CWSI using remote sensing-based methods and integrating it into greenhouse automation systems will become increasingly important in determining irrigation times. Full article

High-volume fly ash cement exhibits drawbacks such as delayed hydration and reduced early-age compressive strength due to the replacement of large amounts of cement with fly ash. In recent years, various studies have been conducted to overcome these limitations by incorporating nanomaterials, such as nano-silica, to promote the hydration of cementitious systems. This study aims to investigate the effect of colloidal nano-silica on the hydration behavior of cement. Cement paste specimens were prepared with varying dosages of colloidal nano-silica to evaluate its influence. To examine the hydration characteristics and mechanical performance, compressive strength tests, isothermal calorimetry, and thermo-gravimetric analyses were conducted. Furthermore, the effect of colloidal nano-silica on the hydration of cement blended with fly ash was also examined. The experimental results revealed that the incorporation of colloidal nano-silica accelerated the hydration reactions in both ordinary and fly ash-blended cement pastes and significantly improved early-age compressive strength. In particular, the 7-day compressive strength of fly ash-blended cement mortar improved by 22.2% compared to the control specimen when 2% colloidal nano-silica was incorporated. The use of colloidal nano-silica appears to be a practical approach for enhancing the early strength of high-volume fly ash concrete, and its broader application and target expansion could contribute to the advancement of a low-carbon construction industry. Full article

The Northeastern China Gravity Monitoring Network (NCGMN; 40–50°N), a pioneering time-variable gravity monitoring system in high-latitude cold-temperate environments, serves as a critical infrastructure for geodynamic investigations of the Songliao Basin, Changbai Mountain volcanic zone, and northern Tan-Lu Fault Zone. To address the data reliability challenges posed by nonlinear dynamic drifts in spring-type relative gravimeters during mobile surveys, this study quantifies—for the first time—the non-smooth normal distribution characteristics of such drifts using the inaugural 2015 dataset from two CG-5 instruments. Results demonstrate a 7–15% reduction in mean dynamic drift rates compared to static conditions, with spatiotemporal variability governed by multi-physics field coupling (terrain undulation, thermal fluctuation, and barometric perturbation). A comprehensive correction framework—integrating a gravimetric line drift rate computation, multi-model validation, and absolute datum cross-validation—reveals gravity value discrepancies up to ±10 μGal across models. The innovative hybrid scheme combines local drift preprocessing (initial-point modeling, line fitting, variance-sum optimization) with global adjustment optimization, achieving the significant suppression of nonlinear drift errors. The variance-sum optimal and Bayesian adjustment hybrid synergizes local variance minimization and global temporal correlation priors, delivering the following: (1) 34% and 29% reductions in segment self-difference standard deviations versus classical and Bayesian adjustments; (2) 24% and 14% decreases in segment residual standard deviations; (3) 12% and 6% improvements in absolute datum cross-validation precision. This study establishes a foundation for the reliable extraction of μGal-level gravity signals, advancing high-precision gravity monitoring of seismicity, volcanic unrest, and fault zone deformation in complex terrains. By harmonizing local-scale accuracy with network-wide consistency, the framework sets a new benchmark for time-variable gravity studies in challenging environments. Full article

Thermodynamic parameters play a crucial role in analyzing and optimizing crystallization processes. In this investigation, the solubility profiles of erythromycin thiocyanate dihydrate were determined gravimetrically under atmospheric pressure (0.1 MPa) across six monosolvent systems (methanol, n-propanol, methyl acetate, ethyl acetate, propyl acetate, and water) and two binary solvent mixtures (water–methanol and water–n-propanol), spanning a temperature range of 278.15–318.15 K. The results showed that the solubility of erythromycin thiocyanate dihydrate is apparently affected by temperature and solvent type. For pure solvents, erythromycin thiocyanate dihydrate has higher solubility in alcohol solvents, and lower solubility in ester solvents and water. In mixed solvent systems, erythromycin thiocyanate dihydrate exhibits reduced solubility with higher water content. The experimental solubility values in monosolvent systems were correlated using the Apelblat, Yaws, and Van’t Hoff models, with the Apelblat model showing the best fitting effect. The Apelblat model, Apelblat Jouyban Acre model, and CNIBS/R-K model were employed for data correlation in binary solvent systems, with the Apelblat model and CNIBS/R-K model showing better fitting results. Full article

The polymorphism of ammonium nitrate has significantly limited its application. Incorporating potassium nitrate into crystals of ammonium nitrate is one of the most commonly used methods to inhibit its polymorphic transition. To accurately prepare crystals of ammonium nitrate with varying contents of potassium nitrate, the solid–liquid phase equilibrium relationship of the quaternary system (NH₄NO₃-KNO₃-H₂O-C₂H₅OH) was studied at 298.15 and 303.15 K. The solubility of components in the equilibrium liquid phase and the composition of the wet-solid phase were determined through formaldehyde titration and gravimetric methods. Based on the solubility data, the phase diagram of the multicomponent system was subsequently constructed. Experimental data demonstrate that the concentration of ammonium nitrate in solution decreases as the potassium nitrate concentration increases. Furthermore, as the ethanol content in the solvent system increases, the equilibrium solubility of ammonium nitrate and potassium nitrate exhibits a concomitant reduction. Correlation analysis of the solubility data for the multicomponent system was performed using the nonrandom two-liquid model. Error analysis demonstrates that the calculated values exhibit satisfactory agreement with the experimental data. Full article

Background: Vibrating mesh nebulizers (VMNs) are not only used to deliver typical pulmonary drugs but are also a promising platform for novel formulations and therapeutic applications. Typically, these devices operate continuously or on demand and are directly connected to the outflow interface (mouthpiece or mask) without valving systems that could spare the drug during exhalation. This paper examines the possibility of increasing the delivery of inhaled budesonide aerosol by attaching a valved holding chamber (VHC) to selected VMNs. Methods: A laboratory in vitro study was conducted for seven budesonide (BUD) nebulization products (0.25 mg/mL). The rates of aerosol delivery from VMNs alone or VMN + VHC systems were determined gravimetrically for a simulated breathing cycle, while droplet size distributions in mists were measured by laser diffraction. Results: The VMN + VHC systems increased the amount of aerosol available for inhalation and the fraction of fine particles that could penetrate the pulmonary region. Depending on the VMN and BUD product, a relative increase of 30–300% in the total drug delivery (T) and 50–350% in the pulmonary drug availability (P) was obtained. The results are explained by the reduction in aerosol losses during exhalation (the fugitive emission) by the VHC and the simultaneous elimination of the largest droplets due to coalescence and deposition in the chamber. Both VMN and BUD affected the aerosol’s properties and discharge mass and thus the actual benefits of the VHC. Conclusions: While the results confirm the superiority of VMN + VHC over VMNs alone in nebulizing BUD suspensions, they also show that it is difficult to predict the effects quantitatively without testing the individual nebulizer–chamber–drug combination. Full article

Monitoring soil moisture content (SMC) remains challenging due to its spatial and temporal variability. Accurate SMC prediction is essential for optimizing irrigation and enhancing water use efficiency. In this research, a Gradient Boosting Regressor (GBR) model was developed and validated to predict SMC in two soil textures, loam and silt loam, using meteorological data from Internet of Things (IoT) sensors and gravimetric SMC field measurements collected from five different depths. The statistical analysis revealed significant variation in SMC across depths in loam soil (p < 0.05), while silt loam exhibited more stable moisture distribution. The GBR model demonstrated high performance in both soil textures, achieving R² values of 0.98 and 0.94 for silt loam and loam soils, respectively, with low prediction errors (RMSE 0.85 and 0.97, respectively). Feature importance analysis showed that precipitation and humidity were the most influential features in loam soil, while solar radiation had the highest impact on prediction in silt loam soil. Soil depth also showed a significant contribution to SMC prediction in both soils. These results highlight the necessity for soil-specific modeling to enhance SMC prediction accuracy, optimize irrigation systems, and support water resources management approaches aligning with SDG6 objectives. Full article

This study examines the influence of gravity on different height systems by integrating Global Navigation Satellite Systems (GNSS), leveling, and gravimetric measurements. Although the theoretical influence of gravity on height systems is well known, empirical studies that quantify these effects along steep terrain are rare—particularly within the Croatian reference systems. Geometric leveling, recognized for its precision in geodesy, was employed alongside gravimetric data to analyze the relationship between gravity variations and height differences. The research was conducted along Sljeme Road on Mt. Medvednica, Croatia, where altitude-dependent gravity effects were systematically investigated along an elevation profile with a height difference of about 650 m. GNSS measurements provided positional coordinates referenced to the Croatian Terrestrial Reference System 1996 (HTRS96) (EPSG:4888), while leveling and gravimetric data were analyzed within the Croatian Height Reference System 1971 (HVRS71) (EPSG:5610) and Croatian Gravimetric Reference System 2003 (HGRS03), respectively. The results demonstrate that differences between geometric and normal–orthometric heights become more pronounced at higher elevations but remain at the millimeter level. Notably, the impact of gravity is evident in normal and orthometric heights, with differences from geometric heights reaching up to 3.7 cm at the highest points. Additionally, a comparison between normal and orthometric heights reveals that at the beginning of the leveling line, the difference is around 4 mm. However, as the elevation increases, this difference grows, reaching over 1 cm at the end of the leveling line. The study also confirms the theoretical correlation between the geoid–quasigeoid height difference and terrain elevation, with increasing differences observed at higher altitudes. To examine the consistency of different height determination methods, two approaches were applied: one based on adjustment within the geopotential system, and the other involving direct adjustment in the desired height system, with specific height corrections applied. The results confirmed that the height differences between the two methods were 0, to the tenth of a millimeter, indicating that both methods provided identical results. These findings contribute to a deeper understanding of geodetic height systems and the role of gravity in height determination. Full article

Soil contamination with heavy metals poses a significant risk to human health and ecological systems through multiple exposure pathways: direct ingestion of crops, dermal contact with polluted soil, and bioaccumulation within the food chain. This study analyses eleven composite soils, each collected in triplicate from different sites in Iași County, four of which are designated Natura 2000 protected areas (Mârzești Forest, Plopi Lake—Belcești, Moldova Delta, and Valea lui David). The assessment includes measurements of soil humidity by the gravimetric method, pH, and organic matter content, examined in relation to heavy metal concentrations due to their well-established interdependencies. For heavy metal determination, energy-dispersive X-ray spectroscopy (EDS) using an EDAX system (AMETEK Inc., Berwyn, PA, USA) and X-ray fluorescence spectrometry (XRFS) with a Vanta 4 analyser (Olympus, Waltham, MA, USA) were employed. Additionally, scanning electron microscopy (SEM) with a Quanta 450 microscope (FEI, Thermo Scientific, Hillsboro, OR, USA) was used primarily for informational purposes and to provide a broader perspective. In the case of chromium, 45.45% of the samples exceeded the permissible levels, with concentrations ranging from 106 mg/kg to 186 mg/kg, the highest value being nearly twice the alert threshold. Notably, not all protected areas maintain contaminant levels within safe limits. The sample from the Mârzești Forest protected site revealed considerably raised concentrations of mercury, arsenic, and lead, exceeding the alert thresholds (1 mg/kg—mercury, 15 mg/kg—arsenic, and 50 mg/kg—lead) established through Order no. 756/1997 issued by the Minister of Water, Forests, and Environmental Protection from Romania. On the other hand, the sample from Podu Iloaiei, an area with intensive agricultural activity, shows contamination with mercury and cadmium, highlighting significant anthropogenic pollution. The findings of this study are expected to raise public awareness regarding soil pollution levels, particularly in densely populated regions and protected ecological zones. Moreover, the results provide a scientific basis for policymakers and relevant authorities to implement targeted measures to manage soil contamination and ensure long-term environmental sustainability. Full article