Chemical Potential Research Articles

Analysis of the state of the surface waters of the Pyasachnik dam

An ecological monitoring survey of the freshwater ecosystem of the Pyasachnik Dam was carried out in the period 2011-2016. The main indicators of surface water quality such as temperature, transparency, electrical conductivity, dissolved oxygen, N–NH4, N–NO2, N–NO3, orthophosphates P, total nitrogen, total phosphorus, and chlorophyll a content were monitored. Hereafter, the obtained results are discussed by years and seasons. The chemical status and ecological potential of the freshwater ecosystem were determined. The investigated surface waters are suitable for irrigation, but with a permanent mandatory monitoring. Keywords: ecological potential, irrigation, physicochemical monitoring, chemical status, chlorophyll

Chitosan Alginate Nanoparticles of Protein Hydrolysate from Acheta domesticus with Enhanced Stability for Skin Delivery.

This study aimed to develop chitosan alginate nanoparticles (CANPs) for enhanced stability for dermal delivery of protein hydrolysate from Acheta domesticus (PH). CANPs, developed using ionotropic pre-gelation followed by the polyelectrolyte complex technique, were characterized for particle size, polydispersity index (PDI), and zeta potential. After the incorporation of PH into CANPs, a comprehensive assessment included encapsulation efficiency, loading capacity, morphology, chemical analyses, physical and chemical stability, irritation potential, release profile, skin permeation, and skin retention. The most optimal CANPs, comprising 0.6 mg/mL sodium alginate, 1.8 mg/mL calcium chloride, and 0.1 mg/mL chitosan, exhibited the smallest particle size (309 ± 0 nm), the narrowest PDI (0.39 ± 0.01), and pronounced negative zeta potential (-26.0 ± 0.9 mV), along with an encapsulation efficiency of 56 ± 2%, loading capacity of 2.4 ± 0.1%, release of 40 ± 2% after 48 h, and the highest skin retention of 12 ± 1%. The CANPs induced no irritation and effectively enhanced the stability of PH from 44 ± 5% of PH remaining in a solution to 74 ± 4% after three-month storage. Therefore, the findings revealed the considerable potential of CANPs in improving PH stability and skin delivery, with promising applications in cosmetics and related fields.

Electrobaryonic axion: hair of neutron stars

Axion-like particles are predicted in many physics scenarios beyond the Standard Model (SM). Their interactions with SM particles may arise from the triangle anomaly of the associated global symmetry, along with other SM global and gauge symmetries, including anomalies with the global baryon number and electromagnetic gauge symmetries. We initiate the phenomenological study of the corresponding “electrobaryonic axion”—a particle that couples with both the baryon chemical potential and the electromagnetic field. Neutron stars, particularly magnetars, possessing high baryon density and strong magnetic fields, can naturally develop a thin axion hair around their surface. In this study, we calculate this phenomenon, considering the effects of neutron star rotation and general relativity. For axion particles lighter than the neutron star rotation frequency, the anomalous interaction can also induce the emission of axion particles from the neutron star. In the light axion regime, this emission can significantly contribute to the neutron star cooling rate.

Cold isospin asymmetric baryonic rich matter in nonlocal NJL-like models

We study the features of low energy strong interactions for a system at zero temperature and finite baryon and isospin chemical potentials, in the framework of a Nambu–Jona-Lasinio-like model that includes nonlocal four-point interactions. We analyze the phase transitions corresponding to chiral symmetry restoration and pion condensation, comparing our results with those obtained from local NJL-like models and lattice QCD calculations. Published by the American Physical Society 2024

Chiral condensate and the equation of state at nonzero baryon density from the hadron resonance gas model with a repulsive mean field

We study the QCD equation of state and the chiral condensate using the hadron resonance gas model with repulsive mean-field interactions. We find that the repulsive interactions improve the agreement with the lattice results on the derivatives of the pressure with respect to the baryon chemical potential up to eighth order. From the temperature dependence of the chiral condensate we estimate the crossover temperature as a function of baryon chemical potential, Tpc(μB). We find that the chiral crossover line starts to deviate significantly from the chemical freeze-out line already for μB>400MeV. Furthermore, we find that the chiral pseudocritical line can be parametrized as Tpc(μB)/Tpc(0)=1−κ2[μB/Tpc(0)]2−κ4[μB/Tpc(0)]4 with κ2=0.0150(2) and κ4=3.1(6)×10−5, which are in agreement with lattice QCD results for small values of μB. For the first time we find a tiny but nonzero value of κ4 in our study. Published by the American Physical Society 2024

Thermoelectric effects in ballistic junctions of 2D-Weyl semimetals

Two dimensional Weyl semimetals are a variant of topological materials in two dimensions, which are realized in three atomic layer materials. These materials possess isotropic or anisotropic dispersions around Weyl nodes and present some common physical properties with their 3D counterparts. We study the thermoelectric effects in a ballistic junction of 2D-Weyl semimetal with isotropic or anisotropic dispersions around the Weyl points. We demonstrate that these two types of 2D-Weyl semimetals exhibit different thermoelectric responses at low chemical potentials of the leads. The Weyl semimetal layer’s physical characteristics can significantly affect these junctions’ thermoelectric properties. Moreover, significant Seebeck coefficient and thermoelectric figure of merit of these junctions are only observed at the low chemical potential of the leads. In particular, we unveil that thermoelectric effects in the ballistic junction of 2D-Weyl semimetals are not as efficient as their 3D counterparts.

Hydrogen and silicon are the preferred light elements in Earth’s core

Hydrogen is an important light element in the Earth’s core for its high cosmochemical abundance and strong affinity to iron under core-formation conditions. Thus, constraining the core composition requires knowledge on the distribution of hydrogen between the liquid outer core and solid inner core. Here we investigate the chemical equilibrium of hydrogen at the inner-core boundary by calculating the chemical potential of hydrogen in solid and liquid iron-hydrogen alloys, respectively, using first-principles molecular dynamic simulations and neural network methods. We find that hydrogen partitions preferentially into the outer core and provides a major contribution to the density jump across the inner-core boundary. Combining geophysical constraints, mineral physics data, and chemical equilibrium, we evaluated light element abundances in the outer and inner cores simultaneously. Our results suggest hydrogen and silicon are the preferred light elements in the core, implying a relatively reduced environment during the Earth’s accretion and core-formation processes.

Characterized on hydrogen properties and mechanism of Al–Sn–Bi composite powder in salt solutions

Using low-melting point elements to promote the Al/H2O reaction has garnered considerable attention because it is an economical approach to hydrogen supply. Herein, .Al–Sn–Bi composite powder was prepared through milling. The Al–Sn–Bi composite powder and the hydrolysate were investigated using X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that the hydrolysis products is primarily AlOOH. The properties of the Al/H2O reaction were systematically characterized in salt solutions. Results show that the presence of Sn and Bi is beneficial to achieve short introduction times and large Al/H2O reaction rates. The hydrogen generation rate of the Al–Sn–Bi composite is 4566 mL min−1 g−1 and 3600 mL min−1·g−1 with NaCl and Na2SO4 solutions, respectively and the hydrogen production efficiency can reach 100% in 1 min. Additionally, the mechanism of Sn and Bi promoting Al/H2O reaction was characterized by density functional theory (DFT) calculations. The DFT calculations show that Sn and Bi replace 1/8 ML, 1/4 ML and 1/2 ML surface atoms of Al (111), the surface chemical potential increases with increasing doping concentration, and the electrode potential decreases with increasing doping concentration. The presence of Sn and Bi increases the surface chemical potential and reduces the electrode potential, this is conducive to the microcell reaction and promotes the Al/H2O reaction.

A domain wall and chiral edge currents in holographic chiral phase transitions

We investigate spatially inhomogeneous solutions in a top-down holographic model: the D3/D7 model which provides a holographic description of the chiral phase transition for a finite external magnetic field, chemical potential, and temperature. We numerically find a domain wall (or kink) solution in the three dimensional space, which incorporates between the chiral symmetry broken phase at the spatial infinity, under the homogeneous sources. Along with the inhomogeneity of the chiral condensate, the charge density is also spatially modulated. The modulated charge density and finite magnetic field lead to the chiral edge current close to the domain wall. We explore the dependences of those profiles on the chemical potential and temperature near the first and second order phase transition points. Our results indicate that the inhomogeneous solutions we found are in good agreement with those obtained by the Ginzburg-Landau theory in the vicinity of the transition points.

Highly Tribo-Positive Nylon-11 Film Fabricated by Multiscale Structural Regulation through a Roll-to-Roll Processing.

Triboelectric polymers have attracted extensive attention due to their great electron-accepting and electron-donating properties in contact electrification as well as their flexible and low-cost merits and have become promising electrode materials in triboelectric nanogenerators (TENGs). However, most research has exclusively focused on improving the electron capture capability of the triboelectric layer, neglecting to enhance the electron-donating capability, which leads to a low output performance of TENG and limits its practical application. In this study, we developed a method to fabricate highly tribo-positive Nylon-11 film through roll-to-roll processing. Paired with the poly(tetrafluoroethylene) triboelectric layer, the transferred charge density of contact-separation TENG based on Nylon-11 film prepared by this method reaches 291.1 μC/m2, which has been improved by 12.4% compared with the conventional compression molding sample. The novel fabricating method can regulate the surface functional groups to achieve higher surface potential and obtain a favorable pseudohexagonal crystal phase, leading to an increasing transferred charge density in triboelectrification. Additionally, it has been analyzed that higher chemical potential of materials can facilitate the transfer of electrons from the triboelectric polymer surface. This study provides a nonadditive, simple, and effective strategy to fabricate excellent tribo-positive material, which can significantly enhance the performance of TENG.

Sound velocity peak induced by the chiral partner in dense two-color QCD

Recently, the peak structure of the sound velocity was observed in the lattice simulation of two-color and two-flavor QCD at the finite quark chemical potential. The comparison with the chiral perturbation theory (ChPT) result was undertaken; however, the ChPT failed in reproducing the peak structure. In this study, to extend the ChPT framework, we incorporate contributions of the σ meson, that is identified as the chiral partner of pions, on top of the low-energy pion dynamics by using the linear sigma model (LSM). Based on the LSM, we derive analytic expressions of the thermodynamic quantities as well as the sound velocity within a mean-field approximation. As a result, we find that those quantities are provided by sums of the ChPT results and corrections, where the latter is characterized by a mass difference between the chiral partners, the σ meson and pion. The chiral partner contributions are found to yield a peak in the sound velocity successfully. We furthermore show that the sound velocity peak emerges only when mσ>3mπ and μq>mπ, with mσ(π) and μq being the σ meson (pion) mass and the quark chemical potential, respectively. The correlation between the sound velocity peak and the sign of the trace anomaly is also addressed. Published by the American Physical Society 2024

Introducing the chemical potential of Cu–Mn–Al alloys for structural, electrical and thermal properties

Introducing the chemical potential of Cu–Mn–Al alloys for structural, electrical and thermal properties

Alkaline earth metal substitutional doped C20: a density functional study

Exploring the structure and electronic properties has become a very interesting subject for nanomaterial application in many fields. This study presents a comprehensive density functional theory exploration of structure and electronic properties of alkaline earth metal (Be, Mg, and Ca) substitutional doped C20 fullerene. The study shows that MC19 (M = Be, Mg, and Ca) cage has elongated M–C bond lengths and expanded C–M–C bond angles. The Be in BeC19 gains a modest charge, while Mg in MgC19 and Ca in CaC19 donate charge. The most amazing result is that MC19 has very large energy gap, which indicates their higher stabilities than C60, and further proved by the larger hardness of MC19 than that of C20. Importantly, the physical interaction mechanism between M and the cage are different for three MC19 structures, which can be proved by the frontier orbital wavefunction and total density of states. The chemical potential values of C20 are larger than that of MC19, indicating their weaker ability to contain electrons and higher activity. Our research will provide the groundwork for rational design and application of such materials in electronic devices and nanotechnology fields. Highlights Substitutioonal doping of Be(Mg, Ca) brings remarkable influence on the geometric structure of C20. The MC19(M = Be, Mg, and Ca) has higher stability than C20. It is evident MC19(M = Be, Mg, and Ca) clusters have none magnetic moment. The chemical potential values of C20 are higher than those of MC19(M = Be, Mg, and Ca). Our research will provide the groundwork for rational design and application of such materials in electronic devices and nanotechnology fields.

Generating terahertz multiple vortex beams using graphene metasurfaces

This paper investigates the generation of orbital angular momentum vortex beams using a graphene metasurface in the terahertz frequency band. The proposed design consists of 20 × 20 unit-cell elements to operate in 1.2 THz applications. Each element is a graphene ring patch printed on a silicon dioxide substrate backed with a polysilicon ground plane of size 75 × 75 × 25 µm3. The graphene reconfigurable surface conductivity is used to control the beam shape, direction, and directivity radiated from the metasurface, through the application of DC biasing voltages. A parametric study on the effect of graphene chemical potential, relaxation time and temperature on the unit-cell reflection properties is introduced. The reflection magnitude varies from − 2.1 dB to -0.8 dB with a 350-degree phase variation for µc ranging from 0.25 eV to 1.6 eV at \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ au$$\\end{document} =5 ps, and T = 300 K. The effect of graphene relaxation time from 0.3 ps to 10 ps on the reflection coefficient at µc = 0.7 eV, and T = 300 K is investigated. The metasurface radiation characteristics are investigated under the illumination of two types of incidence sources, plane-wave, and focused-waves. A depiction of a single vortex beam in various orientations θ = 0, 30o, 50o, and 70o, φ = 90o for l = 1 is presented. The purity of the OAM single beam shows that 94% of the power is concentrated in the designed mode. A graphene metasurface can to convert linearly polarized input into multiple beams exhibiting orthogonal modes. Two/four vortex beams in different directions are demonstrated. The capacity for wireless communication in the terahertz band can be enhanced by utilizing a graphene metasurface.

Compaction and Segregation of DNA in Escherichia coli.

Theoretical and experimental approaches have been applied to study the polymer physics underlying the compaction of DNA in the bacterial nucleoid. Knowledge of the compaction mechanism is necessary to obtain a mechanistic understanding of the segregation process of replicating chromosome arms (replichores) during the cell cycle. The first part of this review discusses light microscope observations demonstrating that the nucleoid has a lower refractive index and thus, a lower density than the cytoplasm. A polymer physics explanation for this phenomenon was given by a theory discussed at length in this review. By assuming a phase separation between the nucleoid and the cytoplasm and by imposing equal osmotic pressure and chemical potential between the two phases, a minimal energy situation is obtained, in which soluble proteins are depleted from the nucleoid, thus explaining its lower density. This theory is compared to recent views on DNA compaction that are based on the exclusion of polyribosomes from the nucleoid or on the transcriptional activity of the cell. These new views prompt the question of whether they can still explain the lower refractive index or density of the nucleoid. In the second part of this review, we discuss the question of how DNA segregation occurs in Escherichia coli in the absence of the so-called active ParABS system, which is present in the majority of bacteria. How is the entanglement of nascent chromosome arms generated at the origin in the parental DNA network of the E. coli nucleoid prevented? Microscopic observations of the position of fluorescently-labeled genetic loci have indicated that the four nascent chromosome arms synthesized in the initial replication bubble segregate to opposite halves of the sister nucleoids. This implies that extensive intermingling of daughter strands does not occur. Based on the hypothesis that leading and lagging replichores synthesized in the replication bubble fold into microdomains that do not intermingle, a passive four-excluding-arms model for segregation is proposed. This model suggests that the key for segregation already exists in the structure of the replication bubble at the very start of DNA replication; it explains the different patterns of chromosome arms as well as the segregation distances between replicated loci, as experimentally observed.

Dielectric resonator antenna with graphene layer and NMP structure for THz applications

Antennas with high performance and technological materials are relevant for several application on THz band. In this work, we investigate the cylindrical dielectric resonator antenna (CDRA) with non-resonant microstrip patch (NMP) feed combined with a thin layer of graphene on the top of the Dielectric Resonator (DR) designed for 3.30 THz. The NMP structure provides high order HEM12δ mode with great advantages in gain values and radiation efficiency. The graphene layer associated with the NMP structure provided improvements in gain and return loss, as well as, tuning characteristics by changing the chemical potential. The antenna was simulated in Ansys HFSS, and the results obtained with NMP radius of 12.7 μm are S11=−37.98 and 7.9dB gain. Besides, the bandwidth increased 6.6% to 20%. These results corroborate the effectiveness and enhancement of the antenna parameters providing a great alternative for Terahertz band applications.

Analysis of a hollow cylinder with variable thermal conductivity and diffusivity by fractional thermoelastic diffusion theory

Based on fractional thermoelastic diffusion theory, an infinite hollow cylinder with variable thermal conductivity and diffusivity is studied. The inner surface of the hollow cylinder is free and subjected to thermal and chemical shocks, while the outer surface is fixed and adiabatic. The closed forms of dimensionless displacement, temperature, chemical potential, stress, and concentration in the Laplace transform domain are given by eigenvalue method. These physical quantities are then numerically obtained through the inverse Laplace transformation. The effects of fractional order parameters, variable thermal conductivity and diffusivity on these quantities are discussed. The present model may be helpful for better understanding the thermoelastic diffusion problems in actual engineering.

Evaluation of absorption behavior of Streptozocin anti-cancer drug on Cr doped Carbon Nanotube (5,5) using DFT theoretical method

In this study, the physicochemical characteristics of the adsorption of the anticancer drug Streptozocin (STZ, Zanosar) on the extern surface of Cr-doped carbon nanotube (CNTCr) have been investigated. Optimization all structures were performed using the DFT method at the mpw1pw91/6-311G level of theory. The energies, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), the density of states (DOS), the distribution of electric charges, and the dipole moments have been calculated to investigate the physical chemistry behaviors of the structures. As well as, the molecular descriptors such as electrophilicity (ω), chemical potential (μ), chemical hardness (h) and chemical softness (S) of compounds were investigated. Examination of the intramolecular and intermolecular bonds indicates that the adsorption of the drug on the nanotube surface has been taking place. Also, the calculated adsorption energy was negative and indicates that the adsorption is thermodynamically possible. All the obtained results of the theoretical calculations have shown that CNTCr is suitable for delivering the anti-cancer drug STZ.

Transverse-electric surface plasmon polaritons in periodically modulated graphene

Transverse-electric (TE) surface plasmon polaritons are unique eigenmodes of a homogeneous graphene layer that are tunable with the chemical potential and temperature. However, as their dispersion curve spectrally lies below the light line, they cannot be resonantly excited by an externally incident wave. Here, we propose a way of exciting the TE modes and tuning their peaks in the transmission by introducing a one-dimensional graphene grating. Using the scattering-matrix formalism, we show that periodic modulation of graphene makes transmission more pronounced, potentially allowing for experimental observation of the TE modes. Furthermore, we propose the use of turbostratic graphene to enhance the role of the surface plasmon polaritons in optical spectra. Published by the American Physical Society 2024

Band structure of the one-dimensional tetrameric Kitaev chain induced by imaginary potentials

We investigate the one-dimensional tetramerised Kitaev chain induced by imaginary potentials {iγ,−iγ,−iγ,iγ} applied to the dimerised Kitaev chain. It is found that the imaginary potentials cause a variety of topological phase transitions. When the chemical potential μ is tuned to the energy zero point, they lead to the appearance of the mixed phase of the system consisting of two purely real Kitaev-like modes and four purely imaginary energy SSH-like zero-energy modes, which appear as the transition of the Kitaev-like-mixed-SSH-like phase. In addition, the Kitaev-like phase can be broadened by imaginary potentials, manifested as the widening of the quantised Andreev reflection plateau. When μ≠0, the same topological phase transition occurs, from the topologically-trivial phase to the Kitaev-like phase. One can believe that this work provides theoretical support for probing the generation of Majorana zero modes in new topological superconducting systems.