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This study presents the design, numerical modeling, and performance analysis of a tunable graphene-based terahertz (THz) sensor exhibiting multiband resonance behavior. The proposed device leverages the unique electro-optical properties of graphene, where modulation of the chemical potential (V) enables dynamic control over the electromagnetic response. This tunability allows real-time ON/OFF operation and precise frequency reconfiguration, resulting in enhanced adaptability for diverse sensing scenarios. The sensor supports four distinct resonance modes at 0.22, 0.35, 0.70, and 0.88 THz, covering a wide portion of the THz spectrum and making it particularly suitable for multiband detection. Simulation results reveal that increasing the chemical potential shifts all resonance modes toward higher frequencies, a consequence of enhanced graphene conductivity and improved impedance matching between the sensor and the surrounding medium. This frequency agility is critical for applications where detection bands need to be dynamically selected or reconfigured. The proposed design exhibits sharp resonance dips, high spectral selectivity, and elevated sensitivity, leading to an impressive figure of merit (FOM) of up to 5.30 RIU⁻ 1 across all operational modes. For a refractive index range of 1.0–1.1, the device achieves sensitivities of 0.51, 0.85, 1.87, and 0.212 THz/RIU for the first to fourth modes, respectively, all within the 0.1–1.0 THz operational window. Such performance metrics position the sensor as a promising candidate for next-generation THz biosensing, non-invasive medical imaging, and chemical or environmental detection, where rapid, reconfigurable, and label-free measurements are essential. Moreover, the multiband capability and tunable nature of the graphene platform open avenues for integrated lab-on-chip sensing systems with adaptive, high-precision operation.

The quark-gluon plasma analysis relies on the heavy quark potential, which is influenced by the anisotropic plasma parameter ( ξ ) , temperature (t), and baryonic chemical potential (μ). Employing the generalized fractional derivative Nikiforov-Uvarov (GFD-NU) method, we solved the topologically-fractional Schrödinger equation. Two scenarios were explored: the classical model (α = β = 1) and the fractional model (α, β < 1). This allowed us to obtain the binding energy of charmonium ( c c ¯ ) and bottomonium ( b b ¯ ) in the 1p state. The presence of the topological defect leads to a splitting between the np and nd states. While increasing the temperature reduces the binding energy, increasing the anisotropic parameter has the opposite effect. Compared to the classical model, the fractional model yields lower binding energies. Additionally, the binding energy further decreases with increasing topological defect parameter, and the influence of the baryonic chemical potential is negligible. We also obtained the wave function for the p-state of charmonium and bottomonium. Here, increasing the anisotropic parameter shifts the wave function to higher values. Moreover, the wave function is lower in the fractional model compared to the classical model. Increasing the topological defect parameter again increases the wave function, while the baryonic chemical potential has no discernible effect.

Context The formulation of conceptual density functional theory in the grand canonical ensemble provides a theoretical framework that allows one to establish additional insights about the response functions that characterize this approach. In particular, through this procedure, one can establish the local counterpart of the chemical potential which, when integrated over all the space, leads to the global quantity and the local counterpart of the hardness that not only provides a function free of ambiguities, but also generates through its integration over all the space the well-defined value of the global quantity given by the difference of the vertical first ionization potential and electron affinity. In the present work, the non-local counterpart of these local reactivity descriptors is derived making use of the Fukui kernel descriptor previously developed by us. Then, the local and non-local chemical potential and hardness, thus obtained, are applied to study site and bond reactivities of several systems, to rationalize the behavior of kinetic and thermodynamic properties, through the chemical information that these indexes provide. Methods The electronic structure calculations required to evaluate the reactivity indexes analyzed in this work were done with the PBE0 exchange–correlation energy functional. The geometry optimization was done in all cases in a modified version of the NWChem program, while the Hirshfeld population analysis was done in a modified version of the demon2k program. For the electrophilic addition of hydrogen halides (HX) to several substituted ethenes and the hydration reaction of aldehydes and ketones, the 6-311G** basis set was used, while for the bond enthalpies of chemical reactions where there is a homolytic bond break and the trans influence in which the lability of the leaving ligand is modified by the ligand opposite to it, the Def2-TZVP was used.

We revisit the role of the electronic chemical potential as the indicator for the tendency of chemical species to attract or donate electrons. Studying a set of 1,3-dipolar cycloadditions shows that the classical Mulliken expression is insufficient in some cases to accurately predict the direction of electron transfer. Agreement with experimental results can be achieved by including the effects of interactions between the reacting partners in the working equation used to calculate the chemical potential. We present a simple revision of the Mulliken expression, inspired by previous work from Gázquez, Cedillo, and Vela, that incorporates the interactions between the reagents in an approximate manner. The revised formula adequately describes the experimental data. We also explore how different methods for computing the ionization potential and electron affinity affect our results.

In this work, we have studied the dissociation behavior of 1S and 2S states of quarkonium using quasiparticle approach where the Debye mass depends on baryonic chemical potential. The binding energies of the quarkonium states has been obtained by using quasiparticle Debye mass which further depends on temperature and baryonic chemical potential ( μ b ). The effect of μ b on the binding energies and the dissociation temperature have been also studied. The binding energy and dissociation temperature of heavy quarkonia decrease as μ b increases. The effect of μ b on the mass spectra of quarkonium states has been studied well.

Using the ratio of two fluctuations in the temperature-dependent density functional theory, the local counterpart of a global response function and the linear (non-local) counterpart of a local response function can be constructed. Here, we analyze the local chemical potential, local hardness, Fukui kernel and dual descriptor kernel and test their performance for describing and interpreting reactivity features for a diverse set of organic chemical reactions, including acid–base reactions, aliphatic nucleophilic substitutions, aromatic electrophilic substitutions and Markovnikov additions. Despite important differences in size and functionalization between some substrates belonging to a given chemical reaction type, temperature-dependent chemical reactivity descriptors were able to reproduce experimental or computational trends in all cases. We identify relevant chemical interactions belonging to a particular family of reactions and the molecular moieties responsible for such interactions. In general, our results are consistent with traditional chemical interpretations. However, in some cases the information contained in the temperature-dependent chemical reactivity descriptors allows one to gain new insights about the organic chemistry reactions considered here.

A new procedure based on the two parabolas model of the energy and the electronic density for fractional electron number is used with the assumption that the changes to the isolated values of these two quantities due to the presence of another interacting species can be incorporated through a multiplicative constant in the second order term. The expressions thus obtained for the chemical potential, hardness, Fukui function and dual descriptor reactivity indexes of conceptual density functional theory have the same form of those obtained through a first order perturbation approach within the grand canonical ensemble. The perturbation parameters are then evaluated by imposing the chemical potential and hardness equalization principles for the interaction between species A and B to form AB, and it is applied to show for a group of substituted ethenes that the condensed to atom perturbed local chemical potential and local hardness evaluated at the carbon atom that follows the Markovnikov’s rule lead to better correlation with the activation energy of their reaction with HCl than the unperturbed descriptors. A similar situation is found for the correlation of the condensed to atom local chemical potential evaluated at N in the aniline molecules with the experimental p K a values. The results obtained indicate that through the perturbed descriptors, that introduce information of the electronic structure on each species of the other one with which it interacts allow one to obtain an improved description of their chemical reactivity.

Electronegativity is a very useful concept but it is not a physical observable; it cannot be determined experimentally. Most practicing chemists view it as the electron-attracting power of an atom in a molecule. Various formulations of electronegativity have been proposed on this basis, and predictions made using different formulations generally agree reasonably well with each other and with chemical experience. A quite different approach, loosely linked to density functional theory, is based on a ground-state free atom or molecule, and equates electronegativity to the negative of an electronic chemical potential. A problem that is encountered with this approach is the differentiation of a noncontinuous function. We show that this approach leads to some results that are not chemically valid. A formulation of atomic electronegativity that does prove to be effective is to express it as the average local ionization energy on an outer contour of the atom’s electronic density.

Focusing on major earthquakes (EQs; MS ≥ 7) in Western China, this study primarily analyzes the fluctuation in Atmospheric Chemical Potential (ACP) before and after the Wenchuan, Yushu, Lushan, Jiuzhaigou, and Maduo EQs via Climatological Analysis of Seismic Precursors Identification (CAPRI). The distribution of vertical ACP revealed distinct altitude-dependent characteristics. The ACP at lower atmospheric layers (100–2000 m) exhibited a high correlation, and this correlation decreased with increasing altitude. Anomalies were detected within one month prior to each of the five EQs studied, with the majority occurring 14 to 30 days before the events, followed by a few additional anomalies. The spatial distribution of anomalies is consistent with the distribution of fault zones, with noticeable fluctuation in surrounding areas. The ACP at an altitude of 200 m gave a balance between sensitivity to seismic signals and minimal surface interference and proved to be optimal for EQ monitoring in Western China. The results offer a significant reference for remote sensing studies related to EQ monitoring and the Lithosphere–Atmosphere–Ionosphere Coupling (LAIC) model, thereby advancing our understanding of pre-seismic atmospheric variations in Western China.

This article deals with the thermodynamics of energy conversion systems with a focus on osmotic membrane and selectively permeable membrane systems for beginners of research in membrane chemistry. Two applications of the concept of the reversible Donnan potential are presented: the irreversible steady-state membrane potential across a biological membrane and irreversible dialytic potential in the dialytic (mixing entropy) batteries. The osmotic pressure and Donnan (membrane) potential are developed as the diffusible species, water and ions of interest, pass through a selectively permeable membrane, followed by mixing with the non-permeating macromolecular ions present in another compartment to finally attain the osmotic equilibrium and the membrane equilibrium, respectively. The former osmotic equilibrium is characterized by the equality of the hydrostatic chemical potential of diffusible water, and the latter membrane equilibrium is characterized by the equality of the combined hydrostatic chemical potential and electrochemical potential of diffusible ions, respectively. The equilibrium Donnan potential is clearly distinguished from irreversible diffusion potential such as the steady-state membrane potential and dialytic potential. The Goldman–Hodgkin–Katz potential and Wagner–Schmalzried potential are briefly introduced and derived on the basis of an electrodiffusion model under the assumption of “the independence principle” for each ion and/or electron participating. Additionally it is justified from the Goldman–Hodgkin–Katz potential and Wagner–Schmalzried potential along with the Daniell potential that the Donnan (Nernst) potential is just the reversible potential across the ideal one single ion permeable membrane and the pure ion-conducting membrane in both directions. Future key issues about the role of the transference number of the ions of interest on a molecular basis in electrochemical kinetics of a variety of membranes should be clarified.