Search Results (279)

Graphene quantum dots (GQDs) obtained by microwave-induced pyrolysis of glutamic acid and triethylenetetramine (trien) are fairly stable, emissive, water-soluble, and positively charged nano-systems able to interact with negatively charged meso-tetrakis(4-sulfonatophenyl) porphyrin (TPPS₄). The stoichiometric control during the preparation affords a supramolecular adduct, GQDs@TPPS₄, that exhibits a double fluorescence emission from both the GQDs and the TPPS₄ fluorophores. These supramolecular aggregates have an overall negative charge that is responsible for the condensation of cations in the nearby aqueous layer, and a three-fold acceleration of the metalation rates of Cu²⁺ ions has been observed with respect to the parent porphyrin. Addition of various metal ions leads to some changes in the UV/Vis spectra and has a different impact on the fluorescence emission of GQDs and TPPS₄. The quenching efficiency of the TPPS₄ emission follows the order Cu²⁺ > Hg²⁺ > Cd²⁺ > Pb²⁺ ~ Zn²⁺ ~ Co²⁺ ~ Ni²⁺ > Mn²⁺ ~ Cr³⁺ >> Mg²⁺ ~ Ca²⁺ ~ Ba²⁺, and it has been related to literature data and to the sitting-atop mechanism that large transition metal ions (e.g., Hg²⁺ and Cd²⁺) exhibit in their interaction with the macrocyclic nitrogen atoms of the porphyrin, inducing distortion and accelerating the insertion of smaller metal ions, such as Zn²⁺. For the most relevant metal ions, emission quenching of the porphyrin evidences a linear behavior in the micromolar range, with the emission of the GQDs being moderately affected through a filter effect. Deliberate pollution of the samples with Zn²⁺ reveals the ability of the GQDs@TPPS₄ adduct to detect sensitively Cu²⁺, Hg^2+, and Cd²⁺ ions. Full article

This study evaluates the feasibility and visibility of electric vehicles (EVs) in Egypt, addressing critical research gaps and proposing actionable strategies to drive adoption. Employing a systematic review of academic, governmental, and industry sources, the paper identifies underexplored areas such as rural–urban adoption disparities, lifecycle assessments of EV batteries, and sociocultural barriers, including gender dynamics and entrenched consumer preferences. Its primary contribution is an interdisciplinary framework that integrates technical aspects, such as grid resilience and climate-related battery degradation, with socioeconomic dimensions, providing a holistic overview of EV feasibility in Egypt tailored to Egypt’s context. Key findings reveal infrastructure limitations, inconsistent policy frameworks, and behavioral skepticism as major hurdles, and highlight the untapped potential of renewable energy integration, particularly through synergies between solar PV generation (e.g., Benban Solar Park) and EV charging infrastructure. Recommendations prioritize policy reforms (e.g., tax incentives, streamlined tariffs), solar-powered charging infrastructure expansion, public awareness campaigns, and local EV manufacturing to stimulate economic growth. The study underscores the urgency of stakeholder collaboration to transform EVs into a mainstream solution, positioning Egypt as a regional leader in sustainable mobility and equitable development. Full article

Protein-polyphenol-based delivery vehicles are effective strategies for encapsulating bioactive compounds, thereby enhancing their solubility and bioaccessibility. In this study, dihydromyricetin/soy protein isolate (DHM/SPI) complexes were used as emulsifiers to prepare Pickering emulsions for DHM delivery. The results show that DHM and SPI form negatively charged complexes through hydrogen bonding, and the complex size decreases and stabilizes with increasing DHM addition. The size of the emulsion droplets was inversely related to the concentration of DHM addition (c), particle concentration (w), and ionic strength (i). Conversely, the increasing oil phase concentration (φ) was positively correlated with droplet size. The CLSM results confirmed the expected oil-in-water emulsion, while the rheological behavior of the Pickering emulsion highlighted its elastic, gel-like network structure and non-Newtonian fluid properties. Moreover, DHM effectively slowed lipid oxidation in the emulsion, and the bioaccessibility of DHM reached 33.51 ± 0.31% after in vitro simulated digestion. In conclusion, this emulsion system shows promising potential for delivering DHM and harnessing its bioactive effects. Full article

Electric vehicles (EVs) offer a sustainable solution for reducing carbon emissions in the transportation sector. However, their increasing widespread adoption poses significant challenges for local distribution grids, many of which were not designed to accommodate the heightened and irregular power demands of EV charging. Components such as transformers and distribution networks may experience overload, voltage imbalances, and congestion—particularly during peak periods. While upgrading grid infrastructure is a potential solution, it is often costly and complex to implement. The unpredictable nature of EV charging behavior further complicates grid operations, as charging demand fluctuates throughout the day. Therefore, efficient integration into the grid—both for charging and potential discharging—is essential. This paper reviews recent studies on the impacts of high EV penetration on distribution grids and explores various strategies to enhance grid performance during peak demand. It also examines promising optimization methods aimed at mitigating negative effects, such as load shifting and smart charging, and compares their effectiveness across different grid parameters. Additionally, the paper discusses key challenges related to impact analysis and proposes approaches to improve them in order to achieve better overall grid performance. Full article

Penta-graphene, a novel two-dimensional carbon allotrope entirely composed of pentagonal carbon rings, has attracted increasing attention due to its unique geometric structure, mechanical robustness, and intrinsic semiconducting nature. In this study, we systematically investigate the adsorption behavior of three typical dissolved gases in transformer oil (CO, C₂H₂, and C₂H₄) on penta-graphene using first-principles calculations based on density functional theory. The optimized adsorption configuration, adsorption energy, charge transfer, adsorption distance, band structure, density of states, charge density difference, and desorption time are analyzed to evaluate the sensing capability of penta-graphene. Results reveal that penta-graphene exhibits moderate chemical interactions with CO and C₂H₂, accompanied by noticeable charge transfer and band structure changes, whereas C₂H₄ shows weaker physisorption characteristics. The projected density of states analysis further confirms the orbital hybridization between gas molecules and the substrate. Additionally, the desorption time calculations suggest that penta-graphene possesses good sensing and recovery potential, especially under elevated temperatures. These findings indicate that penta-graphene is a promising candidate for use in gas sensing applications related to the monitoring of dissolved gases in transformer oils. Full article

Phenylene-based bis-oxamate polydentate ligands offer a unique opportunity for creating a large variety of coordination compounds, in which paramagnetic metal ions are strongly magnetically coupled. The employment of imino nitroxyl (IN) radicals as supplementary ligands confers numerous benefits, including the strong ferromagnetic interaction between Ni and IN. Furthermore, the chelating IN can act as a capping ligand, thereby impeding the formation of coordination polymers. In this study, we present the molecular and crystal structure and experimental and theoretical magnetic behavior of an exceptional neutral trinuclear complex [Ni(L³⁻)₂(IN)₃]∙5CH₃OH (1) (L is N,N′-1,3-phenylenebis-oxamic acid; IN is [4,4,5,5-tetramethyl-2-(6-methylpyridin-2-yl)-4,5-dihydro-1H-imidazol-1-yl]oxidanyl radical) with a cyclic triangular arrangement. Moreover, in this compound three Ni²⁺ ions are linked by the two bis-oxamate ligands playing a rare tritopic function due to an unprecedented triple deprotonation of the related meta-phenylene-bis(oxamic acid). The main evidence of such a deprotonation of the ligand is the neutrality of the cluster, since there are no anions or cations compensating for its charge in the crystals of the compound. Despite the presence of six possible magnetic couplings in the trinuclear cluster 1, its behavior was reproduced with a high degree of accuracy using a three-J model and ZFS, under the assumption that the three different Ni-IN interactions are equal to each other, whereas only two equivalent-in-value Ni-Ni interactions were taken into account, with the third one being equated to zero. Our study indicates the presence of two opposite-in-nature types of magnetic interactions within the triangular core. DFT and CASSCF/NEVPT2 calculations were completed to support the experimental magnetic data simulation. Full article

Polyamide membranes, such as nanofiltration (NF) membranes, are widely used for water purification. However, the mechanisms of solute transport and solute rejection due to solute charge interactions with the membrane remain unclear at the molecular level. Here, we use molecular dynamics simulations to examine the transport of single-solute feeds through charged nanofiltration membranes with different membrane charge concentrations of ${\mathrm{COO}}^{-}$ and NH${}_2^{+}$ resulting from the deprotonation or protonation of polymeric end groups according to the pH level that the membrane experiences. The results show that ${\mathrm{Na}}^{+}$ and ${\mathrm{Cl}}^{-}$ solute ions are better rejected when the membrane has a higher concentration of negatively charged groups, corresponding to a higher pH, whereas ${\mathrm{CaCl}}_2$ is well rejected at all pH levels studied. These results are consistent with those of experiments performed at the same pH conditions as the simulation setup. Moreover, solute transport behavior depends on the membrane functional group distribution. When ${\mathrm{COO}}^{-}$ functional groups are concentrated at membrane feed surface, ion permeation into the membrane is reduced. Counter-ions tend to associate with charged functional groups while co-ions seem to pass by the charged groups more easily. In addition, steric effects play a role when ions of opposite charge cluster in pores of the membrane. This study reveals solute transport and rejection mechanisms related to membrane charge and provides insights into how membranes might be designed to achieve specific desired solute rejection. Full article

Incremental capacity analysis (ICA), where incremental charge (Q) movements associated with changes in potential are tracked, and cyclic voltammetry (CV), where current response to a linear voltage sweep is recorded, are used to investigate the properties of electrochemical systems. Electrochemical impedance spectroscopy (EIS), on the other hand, is a powerful, non-destructive technique that can be used to determine small-signal AC impedance over a wide frequency range. It is frequently used to design battery equivalent-circuit models. This manuscript explores the relationships between ICA, CV and EIS and demonstrates how sweep rate in CV is related to charging (C) rate in ICA. In addition, it shows the connection between observations linked to rate of charge movement in CV and ICA and intermittent, irregular behavior seen in EIS when performed on a battery. It also explains the use of an additional DC stimulus during EIS to ensure reliability of battery impedance data and to facilitate equivalent-circuit modeling, and suggests a method for obtaining data analogous to CV from a whole battery without risking its destruction. Full article

Progressive advancements in the global economy and technology have propelled human civilization forward; however, they have also inflicted significant harm on the global ecological environment. In the present era, electric vehicle (EV) technology is playing a vital role due to its environmentally friendly technological advances. However, widespread adoption of EVs has been hindered by their limited travel range, inadequate charging infrastructure, and high costs. This can be closely observed when we assess the adoption of electric vehicles (EVs) among motorcycle taxi drivers, commonly called ‘pilots,’ in Goa, India. Motorcycle taxis are crucial in Goa’s transportation network, providing affordable, efficient, and door-to-door services, especially in regions with limited public transport options. However, the rising costs of petrol and vehicle maintenance have adversely affected the income of these pilots, prompting concerns about their willingness to adopt EVs. This study aims to analyze the factors prompting the behavioral intention to adopt EVs by motorcycle taxi pilots in Goa, India, focusing on six key determinants: charging infrastructure, effort expectancy, performance expectancy, price value, social influence, and satisfaction with incentive policies. A quantitative approach was employed, utilizing stratified proportionate random sampling techniques to collect data from 242 motorcycle taxi pilots registered with the Goa State Government Transport Department. It was analyzed using partial least squares-structural equation modeling (PLS-SEM) through Smart-PLS 4.0 software. The research highlights that performance expectancy and price value are the potential motivators for the adoption of electric vehicles. These findings suggest that pilots are more likely to embrace EVs when they perceive tangible benefits in performance and find the cost reasonable in relation to the value offered. The results offer actionable insights for policymakers, manufacturers, and other stakeholders. These insights can guide strategic decisions and policy frameworks aimed at fostering a sustainable and user-centric transportation ecosystem. Full article

The excessive input of nitrogen and phosphorus pollutants into surface water bodies poses a serious threat to the aquatic ecosystem. As an efficient porous adsorbent material, ceramsite shows remarkable potential in the field of simultaneous nitrogen and phosphorus removal. In this study, Fe₂O₃ catalyzed the decomposition of K₂CO₃ to generate CO and CO₂ gases, leading to the formation of a large number of pore structures in the composite ceramsite. Subsequently, adsorption experiments were conducted on the obtained ceramsite. The regulatory mechanisms of the ceramsite dosage and solution pH on its adsorption performance were revealed. The experiments show that as the ceramsite dosage increased from 2.1 g/L to 9.6 g/L, the adsorption capacities of ammonia–nitrogen and phosphorus decreased from 0.4521 mg/g and 0.4280 mg/g to 0.1430 mg/g and 0.1819 mg/g, respectively, while the removal rates increased to 68.66% and 58.22%, respectively. This indicates that the competition between the utilization efficiency of adsorption sites and the mass-transfer limitation between particles dominates this process. An analysis of the pH effect reveals that the adsorption of ammonia–nitrogen reached a peak at pH = 10 (adsorption capacity of 0.4429 mg/g and removal rate of 81.58%), while the optimal adsorption of phosphorus occurred at pH = 7 (adsorption capacity of 0.3446 mg/g and removal rate of 86.40%). This phenomenon is closely related to the interaction between the existing forms of pollutants and the surface charge. Kinetic and thermodynamic studies show that the pseudo-second-order kinetic model (R² > 0.99) and the Langmuir isothermal model can accurately describe the adsorption behavior of the ceramsite for ammonia–nitrogen and phosphorus, confirming that the adsorption is dominated by a monolayer chemical adsorption mechanism. This study explores the dosage–efficiency relationship and pH response mechanism of Fe₂O₃-catalyzed porous ceramsite for nitrogen and phosphorus adsorption, revealing the interface reaction pathway dominated by Fe₂O₃ catalysis and chemical adsorption. It provides theoretical support for the construction of porous ceramsite and the development of an efficient technology system for the synergistic removal of nitrogen and phosphorus. Full article

This study focuses on the mathematical modeling, control design, and analysis of an interleaved bidirectional high-voltage-gain DC-DC converter for energy management in supercapacitors. The state of the art is reviewed, with an emphasis on research related to DC-DC converters and energy storage systems. The characteristics and modeling of the supercapacitors are thoroughly analyzed. The converter’s operation in both buck and boost modes is described, detailing its operating stages, design parameters, and component sizing. The modeling accounts for the dynamics of the converter in both operational modes. PI controllers and compensation techniques were implemented to ensure the desired performance and meet the design criteria. Simulations were conducted using PSIM software, version 2023.1, with a power flow of 1 kW, a 48 V DC bus (buck mode), and a 162 V supercapacitor module (boost mode), operating at 500 kHz. The performance of the controllers was evaluated during both the charging and discharging processes of the supercapacitor, analyzing the dynamic response and behavior in the continuous mode, even in the presence of system disturbances. Full article

Charge carrier traps due to crystal defects in GaN on Si HEMT devices are responsible for dynamic performance degradation, long-term reliability limitations, and peculiar failure modes. The behavior of traps depends on many variables including heterostructure quality, the specific device structure, and operating conditions. To study the short time dynamics of charge trapping and release on the threshold voltage shift and hysteresis of commercial normally off GaN HEMTs we use triangular 0–5 V gate voltage pulses in the μs to ms duration range. Measurements are performed for single pulses by varying pulse duration and for a train of a few pulses by varying their number. The results indicate that hysteresis and related threshold voltage shift occur after repeated pulses, suggesting an accumulation of trapped charges. However, for a triangular wave hysteresis vanishes, meaning that a dynamic balance between charge trapping and release is established in the device. This can be considered as a positive indicator of device robustness and reliability. The same method, used to measure the gate threshold voltage shift and dynamic R_ON after a 30 min off-state DC stress at V_DS = 55 V with a floating gate, highlights an appreciable performance degradation of the device. Full article

Electric vehicles (EVs) play a critical role in the transition to sustainable transportation. Despite significant advancements in technology, EVs continue to face major challenges, particularly in terms of limited range, high costs, and insufficient charging infrastructure. This paper presents a comprehensive review that systematically categorizes the multifaceted factors influencing EV range into technical, environmental, user-related, economic, policy, and cultural dimensions. The aim is to offer a holistic view of how these elements interact to shape EV performance, adoption, and usage. Notably, advancements in battery capacity, charging time, vehicle weight, and aerodynamics are identified as key factors that significantly enhance EV range. Environmental factors such as temperature and terrain are shown to drastically impact energy consumption, with cold climates leading to up to a 50% reduction in range. Furthermore, user behaviors, driving patterns, and economic factors like battery costs, charging infrastructure availability, and electricity prices play a crucial role in determining EV efficiency. This review shows the importance of supportive policies, societal attitudes, and infrastructural developments in promoting the widespread adoption of EVs, making it an innovative and timely contribution to the field. Full article

The fission gas uranium mononitride (UN) causes swelling and affects the properties of fission fuel. Since surface behavior is closely related to the release of gases, it is crucial to study the properties of Xe on the UN surface. Density functional theory was used to study the properties of Xe gas on the UN(001) surface and subsurface layers. Different bulk and surface models of UN were established, and the formation energies of bulk and surface defects, as well as the incorporation energy of surface Xe, were calculated. Differential charge density maps were generated, and the analysis revealed that the migration of Xe atoms on the surface predominantly occurs through a vacancy mechanism. Furthermore, Xe atoms located in the subsurface and interstitial positions are less likely to escape from the surface due to the influence of surrounding atoms. Finally, the Climbing Image Nudged Elastic Band method was employed to calculate migration pathways and the associated migration energies. The modelling results indicated that surface Xe atoms’ migration exhibits a vacancy-assisted mechanism, while surface and subsurface U-vacancies on the UN surface may promote the diffusion of fission gas atoms. Full article

As an efficient energy storage solution, lithium-ion batteries (LIBs) play a crucial role in the electric vehicle sector, driving innovation and development in the automotive industry. One common strategy to enhance energy density is to manufacture thicker electrodes. However, the pore distribution in thicker electrodes is often suboptimal, with elongated and tortuous pathways impeding charge transport. Optimizing the pore structure in electrodes is essential for fabricating high-performance batteries. In this study, we performed microwave sintering on lithium cobalt oxide materials and observed the three-dimensional evolution of pores during the sintering process using synchrotron radiation computed tomography (SR-CT).We discovered that pore evolution exhibits directional characteristics. Further analysis revealed that the electromagnetic loss of particles is related to the direction of the electric field, which is the reason for the directional behavior of pore evolution. This research could provide a new potential approach for the fabrication of advanced electrode materials by using electric field control during the battery manufacturing process to align pores vertically, thereby improving both the energy density and charge–discharge rate of the battery. Full article