Large Negative Values Research Articles

Comparing sharp and smooth transitions of the second slow-roll parameter in single-field inflation

In single-field inflation, violation of the slow-roll approximation can lead to growth of curvature perturbation outside the horizon. This violation is characterized by a period with a large negative value of the second slow-roll parameter. At an early time, inflation must satisfy the slow-roll approximation, so the large-scale curvature perturbation can explain the cosmic microwave background fluctuations. At intermediate time, it is viable to have a theory that violates the slow-roll approximation, which implies amplification of the curvature perturbation on small scales. Specifically, we consider ultraslow-roll inflation as the intermediate period. At late time, inflation should go back to the slow roll period so that it can end. This means that there are two transitions of the second slow-roll parameter. In this paper, we compare two different possibilities for the second transition: sharp and smooth transitions. Focusing on effects generated by the relevant cubic self-interaction of the curvature perturbation, we find that the bispectrum and one-loop correction to the power spectrum due to the change of the second slow-roll parameter vanish if and only if theMukhanov-Sasaki equation for perturbation satisfies a specific condition called Wands duality.We also find in the case of sharp transition that, even though this duality is satisfied in the ultraslow-roll and slow-roll phases, it is severely violated at the transition so that the resultant one-loop correction is extremely large inversely proportional to the duration of the transition.

The retention factors and partial molar volumes of cycloartenyl ferulate at infinite dilution in supercritical carbon dioxide: Measurements and correlation

The retention factors and infinite dilution partial molar volumes of a solute in supercritical fluid are crucial for understanding solute–solvent interactions, analyzing pressure effects on chemical reactions, and optimizing industrial processes. Despite their importance, there is a notable scarcity of available data on retention factors and infinite dilution partial molar volumes in supercritical fluid systems. This study presents the first experimental data on the retention factors and partial molar volumes of cycloartenyl ferulate at infinite dilution in supercritical carbon dioxide. The retention factors were measured across temperatures ranging from 308.15 to 353.15 K and pressures of 8.20 to 31.03 MPa using supercritical fluid chromatography. The infinite dilution partial molar volumes were determined by taking the partial derivative of the retention factors with respect to the density of carbon dioxide. The obtained infinite dilution partial molar volumes range from −1.64 × 10−2 to 4.10 × 10−4 m3/mol, with large negative values observed near the critical point of carbon dioxide, indicating strong solvent–solute interactions. In this study, a new correlation model successfully predicts the experimental infinite dilution partial molar volumes with an average absolute relative deviation of 2.3 % over 86 data points.

Modern view on the effectiveness and safety of non-steroidal anti-inflammatory drugs

Issues of the effectiveness and safety of drugs remain relevant and controversial. The benefits and risks of drug therapy are two facets of one whole, called pharmacotherapy, which can have undesirable side and even negatively outweigh the benefits. The effectiveness and safety of drugs must be studied comprehensively because new effects of drugs may be discovered and new mechanisms for unregistered indications may be revealed. Moreover, a deep understanding of adverse drug reactions will allow for the accurate prescription of drugs and proper medical supervision of therapy. Nonsteroidal anti-inflammatory drugs are over-the-counter drugs perceived by patients as safe and do not require a doctor’s prescription, which can cause dangerous drug reactions, particularly when used uncontrollably. The review presents literature data from studies on the effectiveness of nonsteroidal anti-inflammatory drugs and current data on new therapeutic effects of individual drugs, risks of adverse reactions, their mechanisms, and treatment methods.

Broadband dispersion compensation and high birefringence photonic crystal fiber for CWDM/DWDM networks

In this study, we propose a new design based on photonic crystal fibers (PCFs) for broadband dispersion compensation in telecommunication networks. The proposed design has a hexagonal structure arrangement of air-holes rings of different diameters between the silica core and the cladding. The PCF properties like effective area, nonlinearity, dispersion slope, confinement loss, and birefringence are reported and discussed. For the best performance we present three designs A, B and C. Simulation results show that the three designs cover the six-telecommunication optical bands O-, E-, S-, C-, L- and U- bands (wavelengths ranging from 1260 to 1675 nm). Design A achieves a large negative dispersion value of about − 1716 ps/(nm.km) with relative dispersion slope equals to that of conventional single-mode optical fibers (SMFs) of about 0.0036 nm−1, which makes it very suitable for long-haul DWDM transmission systems. With a little modification in the core, designs B and C achieve much higher confinement ability and achieve a very large birefringence value for polarization mode dispersion and sensing applications. Design C is engineered to have exact opposite dispersion of SMF with zero dispersion at the wavelength 1310 nm, which makes it a promising design in CWDM transmission system. The numerical values have been investigated using the full vector finite element method.

Transformation of internal solitary waves at the edge of ice cover

Abstract. Internal wave-driven mixing is an important factor in the balance of heat and salt fluxes in the polar regions of the ocean. Transformation of internal waves at the edge of the ice cover can enhance the mixing and melting of ice in the Arctic Ocean and Antarctica. In the polar oceans, internal solitary waves (ISWs) are generated by various sources, including tidal currents over bottom topography, the interaction of ice keels with tides, time-varying winds, vortices, and lee waves. In this study, a numerical investigation of the transformation of ISWs propagating from open water in the stratified sea under the edge of the ice cover is carried out to compare the depression ISW transformation and loss of energy on smooth ice surfaces, including those on the ice shelf and glacier outlets, with the processes beneath the ridged underside of the ice. They were carried out using a non-hydrostatic model that is based on the Reynolds-averaged Navier–Stokes equations in the Boussinesq approximation for a continuously stratified fluid. The Smagorinsky turbulence model extended for stratified fluid was used to describe the small-scale turbulent mixing explicitly. Two series of numerical experiments were carried out in an idealized 2D setup. The first series aimed to study the processes of the ISWs of depression transformation under an ice cover of constant submerged ice thickness. Energy loss was estimated based on a budget of depth-integrated pseudoenergy before and after the wave transformation. The transformation of ISWs of depressions is controlled by the blocking parameter β, which is the ratio of the minimum thickness of the upper layer under the ice cover to the incident wave amplitude. The energy loss was relatively small for large positive and large negative values of β. The maximal value of energy loss was about 38 %, and it was reached at β≈0 for ISWs. In the second series of experiments, a number of keels were located on the underside of the constant-thickness ice layer. The ISW transformation under ridged ice also depends on the blocking parameter β. For large keels (β<0), more than 40 % of energy is lost on the first keel, while for relatively small keels (β>0.3), the losses on the first keel are less than 6 %. Energy losses due to all keels depend on the distance between them, which is characterized by the parameter μ, i.e. the ratio of keel depth to the distance between keels. In turn, for a finite length of the ice layer, the distance between keels depends on the keel quantity.

Magnetic field-induced phase transition in spinor exciton-polaritons condensate

We theoretically study the magnetic phase transition of condensed exciton-polariton microcavities in an applied magnetic field. When the magnetic field is strong, all polariton spins are polarized parallel to the magnetic field as usual. On the contrary, in the weak magnetic-field region, the polariton polarization degree is negative, namely, anti-parallel to the magnetic field. For a strong magnetic field, the magnetic phase of the polaritons arises and leads to a paramagnetic, while around a weak magnetic field, with zero exciton–photon detunings, and weak Rabi splitting the spin polarization of the polaritons leads to a diamagnetic. Thus, magneto-polariton phase transition polarization originates from the competition between the polariton Zeeman effect and polariton–polariton interactions. Moreover, the polariton polarization strongly depends on the exciton–photon detuning and Rabi splitting and has a large negative value as they are both small. At last, we compare our theoretical results with the experiments and find they match each other very well.

Investigating the effectiveness of borophene on anchoring and influence on kinetics of sodium superoxide in sodium–oxygen batteries

Owing to the increasing cost and limited resources of lithium metal, there is a growing interest in developing energy storage systems that are more affordable, environmentally friendly, and have high energy densities. This is also driven by the need to significantly reduce carbon dioxide emissions resulting from the use of fossil fuels. The sodium–oxygen battery has emerged as a potential alternative, as the materials used for both of its electrodes are among the most abundant and inexpensive elements on Earth. However, despite these advantages, there are technical challenges in implementing it, such as the insulation of the cathode electrode and failure to prevent discharge products from desorbing into electrolytes during discharging. In this study, using density functional theory based on first principles, we investigated the electronic properties of free-standing β12 and χ3-borophenes after adsorption of sodium superoxide (NaO2). Our findings showed that the adsorption energy of sodium superoxide on β12 and χ3 borophene are −3.85 eV and −3.24 eV, respectively. The large negative values of adsorption energy suggest that sodium superoxide is anchored spontaneously, which is significant as it can be prevented from migrating to the negative electrode via the electrolyte during the discharging process. Furthermore, the β12 and χ3 structures showed moderate diffusion energy barriers of 0.89 eV and 1.37 eV and decomposition energies of 0.73 eV and 0.52 eV, respectively. The latter demonstrates the catalytic effects of nanosheets on the decomposition of the sodium superoxide into separated sodium (Na+) and oxygen (O2). Moreover, the decomposition energies being lower than sodium superoxide formation energy (3.90 eV) in a vacuum, suggests nanosheets effects during the charging process. Most importantly, the metallic characteristics of both crystal structures were preserved after the adsorption of sodium superoxide, and the electronic conductivities were enhanced. This is significant to improve the cycle life of the battery, as the materials can charge back the decomposed species during the charging process, thereby preventing the formation of dendrites at the surface of the cathode. Ultimately, the predicted electronic properties for both structures demonstrate their potential as cathode electrode materials for enhancing the electrochemical processes of sodium–oxygen batteries.

Population genetic structure of Indoplanorbis exustus (Gastropoda: Planorbidae) in Thailand and its infection with trematode cercariae.

Indoplanorbis exustus is a freshwater gastropod belonging to the family Planorbidae. This snail is widely distributed across the tropics and plays an important role as the intermediate host for trematodes. However, relatively little is understood regarding the genetic relationship between I. exustus and trematodes. The goals of this study were to investigate the current transmission status of trematode cercariae in I. exustus in Thailand and to examine the genetic diversity, genetic structure, and demographic history of I. exustus. We collected 575 I. exustus from 21 provinces across six regions of Thailand and investigated cercarial infections by using the shedding method. I. exustus from two provinces were infected with cercarial trematodes, and two types of cercarial stages were molecularly identified as furcocercous cercaria and xiphidiocercariae. Phylogenetic tree analysis based on 28S rDNA and ITS2 sequences demonstrated that furcocercous cercaria and xiphidiocercariae were closely clustered with a clade of Euclinostomum sp. and Xiphidiocercariae sp., respectively. Phylogenetic and network analyses of I. exustus haplotypes based on the COI, 16S rDNA, and ITS1 genes demonstrated four main clades. Only snails in clade A were distributed in all regions of Thailand and harbored trematode cercariae. The level of genetic diversity of I. exustus was relatively high, but most populations were not genetically different, thus suggesting the appearance of gene flow within the I. exustus populations. Overall, the haplotype network was star-shaped, thus suggesting the recent demographic expansion of populations. This result was also supported by the unimodal mode of the mismatch distribution graph and the large negative values of the neutrality tests. Therefore, the I. exustus snail was likely another freshwater snail of the invasive species in Thailand. This information will aid in monitoring the spread of the parasitic trematodes carried by I. exustus from different populations.

Environmentally Benign Grape Seed Oil for Corrosion Inhibition: Cutting-Edge Computational Modeling Techniques Revealing the Intermolecular and Intramolecular Synergistic Inhibition Action

The growing interest in eco-friendly alternatives has sparked research into essential oils as corrosion inhibitors, offering an innovative approach. Investigating their unique properties, researchers aim to advance corrosion engineering for a sustainable future. Despite promising lab results, the exact mechanism of their action in corrosion engineering is not fully understood, highlighting the need for further exploration. Using computational modeling, we explored how grape seed oil (GSO) compounds interact with carbon steel (C38) surfaces, unraveling the inhibitive properties against corrosion. Employing various simulation methods, such as density functional theory (DFT), density functional-based tight-binding (DFTB), and molecular dynamics (MD), this study validates experimental findings and unveils novel insights into the underlying mechanisms of these interactions. Quantitative analysis quantifies the inter- and intramolecular synergistic effect and suggests that the LA@OA promotes the charge-transfer process. DFTB calculations reveal that the synergistic action in the parallel adsorption configuration of LA and OA molecules is sufficiently strong to form a stable adsorption layer on the Fe surface with a large negative value of Eads (6.74 eV). Experimental results demonstrated that the inhibition performance of GSO extract exhibited a notable increase with increasing concentrations, reaching a higher efficiency of 79% at 0.5 g/L of GSO. EIS results demonstrated that the existence of the GSO inhibitor film increases the resistance of the charge transfer (about 80 Ω cm2 at 0.5 g/L), indicating the superior barrier anticorrosion properties of the formed film. The theoretical results validate the exceptional anticorrosion performance and provide compelling evidence of the remarkable ability to prevent corrosion of C38 substrate. The findings offer potential pathways for the development of eco-friendly alternatives and interestingly provide a foundation understanding in the field.

Highly sensitive sensing of CO and HF gases by monolayer CuCl.

Using a first-principles approach, the adsorption characteristics of CO and HF on a CuCl monolayer (ML) are studied with Grimme-scheme DFT-D2 for accurate description of the long-range (van der Waals) interactions. According to our study, CO gas molecules undergo chemisorption and HF gas molecules show a physisorption phenomenon on the CuCl monolayer. The adsorption energy for CO is -1.80 eV, which is quite a large negative value compared to that on other previously studied substrates, like InN (-0.223 eV), phosphorene (0.325 eV), Janus Te2Se (-0.171 eV), graphene (P-graphene, -0.12 eV, B-graphene, -0.14 eV, N-graphene, -0.1 eV) and monolayer ZnS (-0.96 eV), as well as pristine hBN (0.21 eV) and Ti-doped hBN (1.66 eV). Meanwhile, for HF, the adsorption energy value is -0.31 eV (greater than that of Ti-doped hBN, 0.27 eV). For CO, the large value of the diffusion energy barrier (DEB = 1.26 eV) during its movement between two optimal sites indicates that clustering can be prevented if many molecules of CO are adsorbed on the CuCl ML. For HF, the value of the DEB (0.082 eV) implies that the adsorption phenomenon may happen quite easily upon the CuCl ML. The transfer of charge according to Bader charge analysis and the variation in the work function depend only on the properties of the elements involved, i.e., their nature, rather than the local binding environment. The work function and band-gap energy variation of the CuCl ML (before and after adsorption) show high sensitivity and selectivity of CO and HF binding with the CuCl monolayer. HF molecules give a more rapid recovery time of 1.09 × 10-7 s compared to that of CO molecules at a room temperature (RT) of 300 K, which indicates that the necessary adsorption and reusability of the CuCl ML for HF can be accomplished effectively at RT. Significant changes in the conductivity are observed due to the CO adsorption at various temperatures, as compared to adsorption of HF, which suggests the possibility of a modification in the conductivity of the CuCl ML.

Non-trivial topological phases in transition metal rich half-Heusler oxides

Topological insulators with gapless surface states and insulating bulk in non-centrosymmetric cubic systems have been extensively explored following the discovery of two-dimensional quantum spin hall effect in zincblende HgTe. In such systems the negative band inversion strength E (= E E 0) governs the robustness of the non-trivial topological states at ambient conditions. Hence, realizing large negative values of E has been a guiding motivation of several investigations reported in literature. Here, we present a material design approach which can be employed to realize large negative values of E in cubic materials such as half-Heusler (HH) oxides with 18 valence electron configurations. We explore 27 HH oxides of the form ABO (A = Li, K, Rb; B = Cu, Ag, Au) in α-, β-, and γ-phase (by placing transition metal atom at different Wyckoff positions) for their non-trivial topological phase. Off these three phases, we found that, the α-phase of nine HH oxides (wherein the transition metal atoms occupy 4a Wyckoff positions in the crystal structure) is the most promising with non-trivial topological phase which is governed by the mass-Darwin fully-relativistic effects enhancing E. Whereas the other phases were found to be either trivial semiconductors or semimetals or metals and most of them being dynamically unstable. We focus on RbAuO in α-phase with E of −1.29 eV and the effect of strain fields on the topological surface states of this compound. We conclude that the α-phase of HH oxide presented here can be synthesized experimentally for diverse room temperature applications in spintronics and nanoelectronics.

Latituditual Structure of Dayside Polar Cusp Precipitation

The results of observations of low-altitude spacecraft crossing the daytime sector of the auroral zone and of high-apogee spacecraft in the equatorial plane of the magnetosphere were analyzed in order to identify the main processes leading to the formation of dayside polar cusps. Observations from the DMSP F7 spacecraft were used to analyze the latitudinal characteristics of ion precipitation in the cusp region and to study the latitudinal profile of ion pressure in the cusp depending on the IMF parameters. A significant difference was found in identifying the cusp boundaries using an automated data processing system and direct analysis of spacecraft observations. It is shown that for small negative values of the Bz-component of the IMF (〈Bz〉 = –3.0 nT), an ordinary feature of the cusp is the latitudinal profile of the ion pressure (Pi) with a width of ~1° of latitude with two maxima, one of which is located in the equatorward and the other in the poleward of the cusp. For large negative Bz values (–6, –8 nT), the polar maximum in the latitudinal profile Pi disappears; only the equatorial maximum remains, the Pi level at the maximum increases, and the width of the cusp decreases to ~0.7°. For Bz IMF 0, the most characteristic is the Pi profile with a maximum ion pressure in the polar part of the cusp. The cusp for Bz 0 is located at higher latitudes than for Bz 0, and its average latitudinal width increase to ~1.4° of latitude. In the prenoon sector MLT, the most typical for periods with a large negative By-component of the IMF (〈By〉 = –6.3 nT, 〈Bz〉 = –1.7 nT) is a cusp with a width of ~1.4° of latitude with a flat top in the latitudinal Pi profile. Comparison of the pressure distributions observed at low heights with data from high-apogee satellites confirmed the possibility of describing the formation of the cusp as a diamagnetic cavity and using observations in the cusp to determine the ion pressure in the magnetosheath.

Study of the physical aspects of Pt3T (T = Mn, Ni) intermetallic compounds using first principles method

Platinum based transitional intermetallic compounds creates significant interest in the research area because of having their promising physical, optical, and electronic properties with the large scale of thermodynamic applications. The main purpose of this study is to examine the several physical properties of intermetallic compounds Pt3T (T = Mn, Ni) explored through density functional theory (DFT). The reliability of this work was made by comparing the investigated mechanical features with previously studied compounds of similar types. The calculated structural parameters have a similarity with experimental values. For the first time, we have calculated as well as presented the elastic constants, Cauchy pressure, bulk, shear, and Young's moduli. The mechanical stability of these compounds is proven by the calculation of elastic constants which meets necessary stability requirements. Metallic and ductile nature of Pt3Mn and Pt3Ni is represented by the Cauchy pressure and Pugh's ratio respectively. High machinability index of Pt3Ni ensured its low friction and huge application in industry. Band structure and DOS calculations also represented the metallic behavior of these compounds. High reflectivity in UV region refers the high conductance characteristics of Pt3T (T = Mn, Ni) in low energy regions. Very high absorption in the UV region is observed here. In the infrared region high refractive index is noticed. The dielectric constant's ε1(ω) large negative value in the real part demonstrates the Drude-like behaviors which are the metallic system's common characteristics. Very high melting temperature of Pt3T (T = Mn, Ni) ensured their probable applications in the high temperature technology. TBC nature of these phases has been ensured from their very low thermal conductivity values.

Multimaterial Additively Manufactured Metamaterials Functionalized with Customizable Thermal Expansion in Multiple Directions.

Metamaterials functionalized with customizable multidirectional coefficient of thermal expansion (CTE) are urgently needed for advanced shape control or dimensional stability under temperature variations. The currently reported metamaterials still lack the development of diverse base material systems and exploration of the multimaterial fabrication process. Especially, the reported range of customizable CTEs for metamaterials in multiple directions is limited within [-68.1, 56.4] ppm/°C. Here, this work explicitly proposes a strategy for closely linking base materials, additive manufacturing (AM) process, architecture, and CTE tunability, in order to provide a general guideline for the design or customization of such metamaterials. In detail, first, we systematically identify the key process parameters and related performance for additive manufacturing of polymers and propose various multimaterial systems such as polypropylene-polycarbonate (PP-PC). Then, six types of metamaterials have been fabricated with high quality by the established multimaterial additive manufacturing. By measuring the effective CTEs in multiple directions, the CTE tunability of metamaterials, including large positive values (+523.36 ppm/°C) and large negative values (-230.61 ppm/°C), far beyond the literature-reported CTE range, has been experimentally verified. Further, we have developed a bidirectional requirement-solution strategy here that acts as a bridge between design and fabrication. This work opens advanced avenues for metamaterials with multidirectionally customizable and extensive CTE tunability for a variety of engineering applications such as actuators, thermal stress relief, and improved structural stability.

Spinning black holes with axion hair

In this work we construct and analyze non-perturbative stationary and axially-symmetric black hole solutions in general relativity coupled to an electromagnetic and an axion field. The axion field is coupled to the electromagnetic field, which leads to hairy solutions in the presence of an electric charge and rotation. We investigate the existence and characteristics of these solutions for different values of the spin, charge and coupling constant. Our analysis shows the presence of violations of the Kerr–Newman bound, solutions with large positive and negative values of the gyromagnetic ratio, and the existence of multiple branches of solutions with distinct properties, demonstrating that black hole uniqueness does not hold in this scenario. The code used in this study is publicly available, providing a valuable tool for further research on this model.

Improving the accuracy of the FMO binding affinity prediction of ligand-receptor complexes containing metals.

Polarization and charge transfer strongly characterize the ligand-receptor interaction when metal atoms are present, as for the Au(I)-biscarbene/DNA G-quadruplex complexes. In a previous work (J Comput Aided Mol Des2022, 36, 851-866) we used the ab initio FMO2 method at the RI-MP2/6-31G* level of theory with the PCM [1] solvation approach to calculate the binding energy (ΔEFMO) of two Au(I)-biscarbene derivatives, [Au(9-methylcaffein-8-ylidene)2]+ and [Au(1,3-dimethylbenzimidazole-2-ylidene)2]+, able to interact with DNA G-quadruplex motif. We found that ΔEFMO and ligand-receptor pair interaction energies (EINT) show very large negative values making the direct comparison with experimental data difficult and related this issue to the overestimation of the embedded charge transfer energy between fragments containing metal atoms. In this work, to improve the accuracy of the FMO method for predicting the binding affinity of metal-based ligands interacting with DNA G-quadruplex (Gq), we assess the effect of the following computational features: (i) the electron correlation, considering the Hartree-Fock (HF) and a post-HF method, namely RI-MP2; (ii) the two (FMO2) and three-body (FMO3) approaches; (iii) the basis set size (polarization functions and double-ζ vs. triple-ζ) and (iv) the embedding electrostatic potential (ESP). Moreover, the partial screening method was systematically adopted to simulate the solvent screening effect for each calculation. We found that the use of the ESP computed using the screened point charges for all atoms (ESP-SPTC) has a critical impact on the accuracy of both ΔEFMO and EINT, eliminating the overestimation of charge transfer energy and leading to energy values with magnitude comparable with typical experimental binding energies. With this computational approach, EINT values describe the binding efficiency of metal-based binders to DNA Gq more accurately than ΔEFMO. Therefore, to study the binding process of metal containing systems with the FMO method, the adoption of partial screening solvent method combined with ESP-SPCT should be considered. This computational protocol is suggested for FMO calculations on biological systems containing metals, especially when the adoption of the default ESP treatment leads to questionable results.

The new solid solution of double transition metal MXenes: Atomistic modeling of two-dimensional YScX (X= C and N)

In this paper, the structural and dynamical stability, electronic, optical, and thermodynamic properties of a new solid solution of two transition metals YScX (X = C and N) MXenes have been studied. The calculation is carried out based on density functional theory (DFT) and the pseudopotential technique. The results obtained from the structural, thermodynamical, and dynamical stability have shown that 2D YScC and YScN MXenes are structurally stable and their experimental synthesis is possible. Total density of states and band structure calculations show that YScX (X = C and N) MXene exhibits metallic behavior using LDA, GGA, and GGA + HSE06 approximations. According to the total density of states results, it can be concluded that the YScX MXenes have a pseudogap close to the Fermi level and at the left side, which justifies the structural stability of the studied monolayers. The plots of electron charge density distribution and electron localization function justify the metallic nature of the mentioned structures. The large negative values of the real part of the dielectric function indicate that 2D YScX (X = C and N) MXenes have a metallic Drude-like behavior. The saturation of the surface of 2D monolayers with various F, O, OH, and H functional groups does not change the metallic properties, the only exception that reveals the semiconductor property in the HSE06 method is YScCH2 Mxene where no atomic orbital intersects the Fermi level. In addition, the onset of the absorption spectrum of YScX (X = C and N) MXenes corresponds to zero photon energy, which is a confirmation of the metallic properties of the investigated structures. The GGA + HSE06 method enables faster electromagnetic beam propagation through the 2D materials, particularly in the x-direction of the hexagonal structure, resulting in a lower absorption coefficient and optical conductivity of 2D monolayers compared to the GGA method. The rising trend of entropy with temperature provides evidence for the endothermic behavior of YScC and YScN monolayers. Unlike heat capacity, the Debye temperature of YScX (X = C and N) MXenes decreases with respect to temperature T, according to the inverse relationship between the Debye temperature and the heat capacity. Due to structural and dynamic stability and layered structure with the nature of covalent and metallic bonds, YScX MXenes are a suitable choice for use in electrical connections and as a protective coating with a low friction level.

Brainwave activities reflecting depressed mood: a pilot study

Early diagnosis and treatment of depression are desirable but currently difficult due to a lack of established biomarkers. Although biomarkers for depression based on electroencephalogram (EEG) data have long been explored, most existing methods are thought to capture cognitive decline caused by depression and are unsuccessful in detecting signs of depression. Here we report that some brainwave activities involving phase resetting reflect the depressed mood at the time, which can be easily monitored by measuring the resting EEG with eyes closed for 1 min with a few electrodes. We instructed 10 participants (nine healthy and one diagnosed with depression, aged 18–34) to record their EEG for 14–26 days. We found that indicators of depressed mood were correlated with the occurrence frequency of EEG phase resetting. For most participants, the correlation coefficients swung systematically between large positive and large negative values with respect to EEG frequency; however, the frequencies at which they were maximum or minimum differed among participants. Although this study is in the pilot phase and needs further experimentation, the results are expected to lead to innovative biomarkers for early detection of depression and may contribute to a better understanding and treatment of depression.

Simultaneous Production and Consumption of Soil N2O Creates Complex Effects on Its Stable Isotope Composition

AbstractThe stable N and O isotope composition of soil and soil‐respired N2O is increasingly measured, yet a solid theoretical framework for interpreting the data remains to be developed. Here, the physical processes that affect soil N2O and its isotopes are embedded in a diffusion/reaction model. Numerical experiments are compared to data to demonstrate how various soil processes influence depth profiles and surface fluxes of soil N2O, δ15NN2O, and δ18ON2O. Model predictions and data suggest that the isotope composition of the net N2O soil flux, in soils that have N2O consumption, is a function of the net flux rate, and the isotope differences between the atmosphere and the biological source. Asymptotically large negative or positive δ15Nflux and δ18Oflux values occur as the net soil N2O flux approaches zero from positive or negative flux rates, respectively. This implies that the isotopic imprint of soil fluxes on the global atmospheric N2O pool is more variable than previously suggested. Additionally, the observed isotope values in static flux chambers are possibly complicated by the fact that consumption fluxes increase as the concentration in the chambers increases. This work reveals that even simple chamber flux measurements may possess isotope effects imparted by consumption during the chamber measurement and suggests ways to experimentally test this possibility. Additionally, simple methods to estimate depth‐dependent net production/consumption and its isotope effects are suggested. However, understanding the gross rates of the production and consumption of soil N2O remains an elusive goal.

Discharge characteristics of a low-pressure geometrically asymmetric cylindrical capacitively coupled plasma with an axisymmetric magnetic field

We investigate the discharge characteristics of a low-pressure geometrically asymmetric cylindrical capacitively coupled plasma discharge with an axisymmetric magnetic field generating an E × B drift in the azimuthal direction. Vital discharge parameters, including electron density, electron temperature, DC self-bias, and electron energy probability function (EEPF), are studied experimentally for different magnetic field strength (B) values. A transition in the plasma parameters is observed for a specific range of magnetic fields where the discharge is highly efficient with lower electron temperature. Outside this range of magnetic field, the plasma density drops, followed by an increase in the electron temperature. The observed behavior is attributed to the transition from geometrical asymmetry to magnetic field-associated symmetry due to reduced radial losses and plasma confinement in the peripheral region. The DC self-bias increases almost linearly from a large negative value to nearly zero, i.e., it turns into a symmetric discharge. The EEPF undergoes a transition from bi-Maxwellian for unmagnetized to Maxwellian at intermediate B and finally becomes a weakly bi-Maxwellian at higher values of B. The above transitions present a novel way to independently control the ion energy and ion flux in a cylindrical capacitively coupled plasma system using an axisymmetric magnetic field with an enhanced plasma density and lower electron temperature that is beneficial for plasma processing applications.