Journals
2026 EN
Quan Nguyen Vinh · Son Nguyen Ngoc
ABSTRACT This paper presents a hybrid control strategy for a non‐inverting Buck–Boost DC–DC converter used in photovoltaic energy management. The converter employs two independent Buck and Boost stages, enabling decoupled control loops and fast tracking of rapidly varying reference signals. A combined PI–SMC framework is proposed, where the outer loop regulates the output voltage using a PI controller, and the inner loop controls the inductor current via a smooth Sliding Mode Control (SMC) law based on an arctan(s) switching function. This smooth SMC formulation effectively reduces chattering and high‐frequency oscillations while improving tracking accuracy and robustness. Simulation results show short settling time, fast recovery under abrupt input and load variations, and stable performance across the full Buck–Boost operating range. Quantitative NRMSE (Normalized Root Mean Square Error) analysis confirms high tracking quality, with the output voltage exceeding 90% and the inductor current reaching about 98%. Experimental implementation on a TMS320F28379 DSP further validates the proposed method. The results demonstrate improved disturbance rejection and reduced sensitivity to parameter uncertainties, making the approach well suited for practical renewable‐energy power converters.
Journals
2026 EN
Okada Takuya · Sasaki Tsubasa · Oono Taku
+2 more
Electron injection stability is crucial for organic semiconductors. Although phenanthroline (Phen) derivatives are stable and efficient electrode modification materials, their air stability is underexplored, and the impacts of environmental factors on Phen‐modified electrodes are not well understood. This study investigates the degradation of Phen‐modified organic light‐emitting diodes (OLEDs) by monitoring temporal changes in the light‐emitting area under ambient air exposure without encapsulation. The results demonstrate that Phen modification stabilizes electron injection under room‐temperature and atmospheric‐pressure conditions. The degradation behavior is consistent with Fick's law of diffusion. A strong correlation between the degradation rate and relative humidity indicates a mechanism wherein water molecule diffusion governs the degradation process. The film densities of Phen derivatives are calculated using molecular dynamics simulations. High‐density modifier films may physically hinder water diffusion, suppressing degradation. These findings highlight the potential of Phen‐based materials to enable high‐performance organic electronics with efficient electron injection and enhanced stability under minimal encapsulation.
Journals
2026 EN
Raj R S Arun · Joseph Aruna · Suresh S.
+1 more
ABSTRACT The electrochemical performance of ZnFe 2 O 4 is enriched at 50% Ni substitution in Zn sites with a specific capacitance of 209 F/g. Lindstrom's power law and Dunn's model studies in cyclic voltammograms of Zn 1−x Ni x Fe 2 O 4 electrodes reveal that charge storage in the electrodes occurs through redox reactions involving the intercalation of electrolyte ions deep into the electrodes (intercalation pseudocapacitance) and the adsorption of electrolyte ions on the surface or near the surface of the electrodes (redox pseudocapacitance), simultaneously. This enhancement in specific capacitance and contribution of intercalation and redox pseudocapacitance is the cumulative involvement of various facets such as: (i) crystallite/grain size, (ii) electronic transitions, (iii) availability of active sites, and (iv) the ion diffusion pathways in the electrodes. The variation in crystallite size with respect to Ni substitution has been evaluated through quantitative analysis of XRD patterns. Quantification of XPS spectra reveals the existence of multivalent states of metal ions and the oxygen vacancies, which influence the active sites and ion diffusion pathways in the electrode. Qualitative analysis of the optical properties in the UV–Vis–NIR region divulges that Zn 1−x Ni x Fe 2 O 4 electrodes exhibit several electronic transitions, such as ligand to metal transitions (LMCT) between oxygen and metal ions, intervalence charge transitions (IVCT) between (Fe 2+ /Ni 2+ ) and Fe 3+ ions, and crystal field (CF) transitions occurring in Fe 3+ , Fe 2+ , and Ni 2+ ions. The Ni 2+ incorporation affects the gap between the electronic states involved in each transition by creating defect states between them. This, in turn, impacts the faradaic charge transfer between the electrolyte ions and electrodes during intercalation and adsorption of electrolyte ions. To evaluate practical performance, a symmetric 2‐electrode cell was assembled using Zn 0.5 Ni 0.5 Fe 2 O 4 electrodes, which had shown superior specific capacitance in the three‐electrode assembly. The symmetric cell exhibits 116% cyclic stability after 10 000 cycles, and delivers an energy density of 5 Wh/kg and a power density of 2050 W/Kg. This highly capacitive retention nature of Ni‐substituted ZnFe 2 O 4 electrodes makes them potential candidates for energy storage devices, and the exhibition of multiple pseudocapacitive charge storage mechanisms delivers high energy and power density.
Journals
2026 EN
Mishra Mudit · Kumar Sandeep · Sharma Chandra Prakash
+1 more
Abstract Functionally graded materials (FGMs) enhance the mechanical performance of homogeneous materials, while architected periodic structures enable lightweight designs with superior properties. This study investigates wave propagation in functionally graded re‐entrant lattice (FG‐RL) structures, combining the advantages of FGMs and architected lattices. The unit cell comprises three Timoshenko beam elements made of FGMs, incorporating axial deformation material properties varying through the thickness according to power‐law, exponential, and trigonometric gradation profiles. Wave propagation analysis is carried out using the dynamic stiffness method (DSM) coupled with the Floquet–Bloch theorem, and the resulting eigenvalue problem is solved via the Wittrick–Williams algorithm. Two modeling approaches are explored: assigning identical power‐law indices to all beams, and using different indices for each beam. Results reveal that increasing the power‐law index reduces wave speed and shifts the frequency range without altering the overall shape of the dispersion curves. Additionally, material heterogeneity within the unit cell introduces bandgaps. The accuracy of the proposed method is validated through comparisons with FEM and COMSOL Multiphysics results. This work highlights the effectiveness of FGMs in tuning wave propagation behavior and offers a reliable framework for the design of advanced lattice structures with customizable dynamic characteristics.
Journals
2026 EN
Patra Trisha · Dey Sanjit · Barman (Mandal) Soma
Abstract Apoptosis, traditionally regarded as a straightforward cell‐suicide process triggered by cellular stress, plays a vital role in development, immune function, and disease progression. This research presents a synthetic model of the intrinsic (mitochondrial) apoptosis pathway, focusing on programmed cell death initiated by severe DNA damage. Through an in vitro approach, the study quantitatively analyzes apoptotic behavior using mathematical formulations of key regulatory proteins, modeled with ordinary differential equations using Law of Mass Action. A comprehensive system model is developed to capture the full signaling cascade of apoptosis. Furthermore, a novel cytomorphic model is introduced, employing Metal Oxide Semiconductor (MOS) technology to simulate molecular dynamics by drawing parallels with electron flow in transistors. The analytical output of the model reveals time‐dependent protein activity profiles, accurately representing the distinct phases of apoptosis. Notably, simulations show a rapid rise in Caspase‐3 activity following an apoptotic trigger, consistent with its role as an executioner caspase. The electronic circuit model is validated against experimental data from cell culture studies, reinforcing its accuracy and biological relevance. Additionally, the hardware implementation of the apoptosis‐based cytomorphic system is realized using the NI myRIO 1900 tool, demonstrating practical feasibility and integration potential. These findings demonstrate that MOS‐based electronic analogs of apoptosis pathways can effectively mimic protein behavior, offering a faster, more cost‐effective, and safer platform for pharmaceutical research and drug development.
Journals
2026 EN
Patil Mukund A. · Mukhopadhyay Tanmoy · Naskar Susmita
Abstract This paper presents a superconvergent meshless numerical approach based on generalized differential quadrature method to analyze the dynamic behavior of bidirectional functionally graded aluminum‐Terfenol‐D beams with twisted geometry. The power‐law exponent model is exploited to modify the material properties, such as Young's modulus and mass density, over the whole thickness and longitudinal direction of the bidirectional functionally graded aluminum‐Terfenol‐D beams. The influences of Terfenol‐D's bidirectional gradation, porosity volume fraction index, twisted angle, and viscoelastic boundary conditions are investigated on the dynamic characteristics with the notion of developing a design‐oriented mapping of the input parameter space. Subsequently, the study delves into the effectiveness of Terfenol‐D in vibration control for complex twisted structural systems. Computational investigations are conducted to demonstrate the impact of gain control, and the characteristics and optimal arrangement of Terfenol‐D patches on the dynamic response of active sandwich beams under transverse impulsive loads. The findings show that the implementation of active vibration control exploiting Terfenol‐D's magnetostrictive qualities can have a significant impact on reducing the oscillations of bidirectional functionally graded beams. The control studies reveal that placing five Terfenol‐D patches atL / 5 $L/5$ provides the most effective damping, compared to placement atL / 3 $L/3$ or using a full Terfenol‐D layer. The findings highlight the potential of strategically graded and patch‐configured magnetostrictive layers for tailoring vibration behavior in complex structural systems.
Journals
2026 EN
Jampaiboon Natthapong · Atthapak Chaya · Bovornratanaraks Thiti
+2 more
Abstract This study presents a comprehensive first‐principles investigation ofHf 1 − αY α B 2 ${\rm Hf}_{1-\alpha }{\rm Y}_{\alpha }{\rm B}_{2}$ andHf 1 − βY β B 12 ${\rm Hf}_{1-\beta }{\rm Y}_{\beta }{\rm B}_{12}$ , focusing on their thermodynamic stability and mechanical behavior. The results reveal that, at absolute zero, Hf‐richHf 1 − αY α B 2 ${\rm Hf}_{1-\alpha }{\rm Y}_{\alpha }{\rm B}_{2}$ with0 ≤ α ≤ 0.5 $0\le \alpha \le 0.5$ , is thermodynamically stable, whereas Y‐richHf 1 − αY α B 2 ${\rm Hf}_{1-\alpha }{\rm Y}_{\alpha }{\rm B}_{2}$ with0.5 < α < 1 $0.5<\alpha <1$ andHf 1 − βY β B 12 ${\rm Hf}_{1-\beta }{\rm Y}_{\beta }{\rm B}_{12}$ with0 ⩽ β < 1 $0slant \beta <1$ are unstable against decomposition into relevant competing phases, i.e.,Hf 0.5 Y 0.5 B 2 ${\rm Hf}_{0.5}{\rm Y}_{0.5}{\rm B}_{2}$ solid solution andYB 2 ${\rm YB}_{2}$ for Y‐richHf 1 − αY α B 2 ${\rm Hf}_{1-\alpha }{\rm Y}_{\alpha }{\rm B}_{2}$ andHfB 2 ${\rm HfB}_{2}$ ,YB 12 ${\rm YB}_{12}$ and α $\alpha$ ‐rhombohedral B forHf 1 − βY β B 12 ${\rm Hf}_{1-\beta }{\rm Y}_{\beta }{\rm B}_{12}$ . However, near‐stability of Y‐richHf 1 − βY β B 12 ${\rm Hf}_{1-\beta }{\rm Y}_{\beta }{\rm B}_{12}$ , where0.875 ≤ β < 1 $0.875\le \beta <1$ , with formation energies within 4 meV per atom above the Hf−Y−B convex hull implies its potential entropy‐driven thermodynamic stabilization at elevated temperatures. BothHf 1 − αY α B 2 ${\rm Hf}_{1-\alpha }{\rm Y}_{\alpha }{\rm B}_{2}$ andHf 1 − βY β B 12 ${\rm Hf}_{1-\beta }{\rm Y}_{\beta }{\rm B}_{12}$ are mechanically stable, according to the Born stability criteria, and Vegard's law is largely obeyed for their structural parameters and elastic moduli. Hf‐richHf 1 − αY α B 2 ${\rm Hf}_{1-\alpha }{\rm Y}_{\alpha }{\rm B}_{2}$ exhibits superhard behavior with a maximum Vickers hardness of 43.9 GPa at α $\alpha$ = 0.167, while that ofHf 1 − βY β B 12 ${\rm Hf}_{1-\beta }{\rm Y}_{\beta }{\rm B}_{12}$ ranges between 33 and 39 GPa and peaks at 38.2 GPa for β $\beta$ = 0.875. The maximum Vickers hardness values ofHf 1 − αY α B 2 ${\rm Hf}_{1-\alpha }{\rm Y}_{\alpha }{\rm B}_{2}$ andHf 1 − βY β B 12 ${\rm Hf}_{1-\beta }{\rm Y}_{\beta }{\rm B}_{12}$ surpass those of their constituent compounds. These findings offer fundamental insights into stabilities and mechanical performance of theHfB 2 ${\rm HfB}_{2}$ − YB 2 ${\rm YB}_{2}$ andHfB 12 ${\rm HfB}_{12}$ − YB 12 ${\rm YB}_{12}$ mixtures, providing theoretical guidance for future development of advanced metal boride‐based hard‐coating materials.
Journals
2026 EN
Waheed Wajiha · Mustafa Irfan · Ul Haq Sami
+2 more
ABSTRACT This study explores the effects of a spatially varying magnetic field on the flow and heat transfer of a power‐law non‐Newtonian fluid past a stretchable porous wedge within a Darcy–Forchheimer porous medium. A mathematical framework is developed by extending the Navier–Stokes and energy equations, incorporating the Cauchy stress tensor for power‐law fluids, Darcy's law, Forchheimer's inertial correction, and Lorentz force effects. The governing partial differential equations are transformed into a system of nonlinear ordinary differential equations via a local non‐similar transformation, treating dimensionless parameters as streamwise independent. The resulting system is solved using a finite difference method (FDM) in MATLAB, generating 200 data points for velocity, temperature, skin friction, and Nusselt number. These results are further employed to train a supervised artificial intelligence model based on the Levenberg‐Marquardt Scheme–Artificial Neural Network (LMS‐ANN), with 70% of data used for training and 15% each for validation and testing. Comparative analysis demonstrates excellent agreement between FDM and LMS‐ANN, achieving mean squared errors as low as 2.6 × 10 −7 for skin friction and 6.6 × 10 −8 for Nusselt number. The study confirms that Darcy–Forchheimer effects significantly enhance velocity and heat transfer, establishing the LMS‐ANN framework as a reliable and efficient predictive tool.
Journals
2026 EN
Baral Asmit · Nakarmi Kanchan · Mänttäri Mika
+1 more
ABSTRACT Microalgal biomass has emerged as a valuable resource in recirculating aquaculture systems (RAS), due to its natural capacity to recover nutrients. In addition, microalgae are potential source of fish‐feed in the aquaculture industry. However, its application in RAS needs careful consideration, as microalgae can interact with geosmin, a common off‐flavor compound found in RAS, which may taint fish quality and makes it unsaleable for the market. In this study, we investigate the potential interaction between geosmin and different microalgal strains, Nannochloropsis oculata and a consortium of Tetraselmis suecica and Phaeodactylum tricornutum , including both living and dead biomasses. Experimental studies with dead biomass revealed that N. oculata and the microalgal consortium can uptake geosmin with an efficiency of 53 ± 0.48% and 25 ± 1.63% over 24 h, respectively. Similarly, with living biomass, uptake efficiencies were 54 ± 0.68% and 42 ± 4.14%, respectively. Based on the higher uptake efficiency, N. oculata was selected for further investigation. Different non‐linear isotherm models (Langmuir, Freundlich, and Henry's Law), kinetic models (pseudo‐first order model, pseudo second‐order model, and Elovich model), and desorption study were used to understand potential sorption mechanisms and assess risks associated with geosmin accumulation in microalgal biomass. Geosmin adsorption by dead N. oculata was best described by Henry's isotherm law and the pseudo‐second order kinetic model, while adsorption on living biomass aligned best with Langmuir isotherm model and the pseudo‐second order kinetic model. Geosmin is released higher from living biomass (79 ± 3.18%) than dead biomass (47 ± 1.74%) when desorbed in water, suggesting harvested microalgae may contain geosmin. While microalgal water treatment combined with biomass utilization for fish feed fits very well within the circular economy, more research is needed to ensure the safe use of microalgal biomass.
Journals
2026 EN
Zaulet Adnana · NuezMartinez Miquel · Hirva Pipsa
+3 more
ABSTRACT Coulomb's law predicts that like‐charge ions repel and avoid dimerization. However, a class of dimers between like‐charge ions is characterized. The [3,3’‐Fe(1,2‐C 2 B 9 H 11 ) 2 ] − (abbreviated as [ o ‐FESAN] − ) represents an innovative non‐classical inorganic anion apart from hydroxyanions that exhibits anion‐anion stabilization via dihydrogen bonding. Experimental methods (nuclear magnetic resonance [NMR], dynamic light scattering [DLS], and X‐ray diffraction) and theoretical approaches (density functional theory) reveal that [ o ‐FESAN] − clusters aggregate by overcoming long‐range electrostatic repulsion. The synthesis of [H 3 O][ o‐ FESAN]•3H 2 O and its crystal structure confirm the formation of stabilized anion‐anion aggregates, with [H 3 O] + counterions residing freely in the channels rather than between the anionic clusters. The structure exhibits the cisoid rotamer, which facilitates the ability of the anionic [ o ‐FESAN] − cluster to form interactions stabilized by dihydrogen bonds (head‐to‐middle cluster) shorter than the sum of the Van der Waals radii. These shorter bonds are crucial for the formation of anion‐anion interactions mediated by dihydrogen bonds. X‐ray structures show that anions aggregate in the solid state, overcoming long‐range electrostatic repulsion through dihydrogen bonds, which are distinct from the hydrogen bonds commonly observed in anion systems involving highly electronegative elements. Consistent with crystal structure evidence, 1 H NMR, transmission electron microscopy, and DLS confirm [ o ‐FESAN] − anion‐anion aggregates in solution. Theoretical calculations support the formation of these anion‐anion aggregates, primarily via C cluster ‐H···H‐B bonds. While individual B‐H···H‐B interactions are weakly attractive, their cumulative effect significantly enhances aggregate stability. Additionally, the crystal structure of Na(H 2 O) 3 [ o ‐FESAN] is reported and analyzed, providing further evidence of unconventional interactions stabilized by dihydrogen bonds.