Density Slope Research Articles

Aperiodic (1/f) neural activity robustly tracks symptom severity changes in treatment-resistant depression.

A reliable physiological biomarker for Major Depressive Disorder is essential for developing and optimizing neuromodulatory treatment paradigms. This study investigates a passive electrophysiologic biomarker that tracks changes in depressive symptom severity on the order of minutes to hours. We analyze brief recordings from intracranial electrodes implanted deep in the brain during a clinical trial of deep brain stimulation for treatment-resistant depression in 5 human subjects (nfemale= 3, nmale = 2). This surgical setting allows for precise temporal and spatial sensitivity in the ventromedial prefrontal cortex, a challenging area to measure. We focused on the aperiodic slope of the power spectral density, a metric reflecting the balance of activity across all frequency bands and serving as a proxy for excitatory/inhibitory balance in the brain. Our findings demonstrate that shifts in aperiodic slope correlate with depression severity, with flatter (less negative) slopes indicating reduced depression severity. This significant correlation was observed in all N=5 subjects, particularly in the ventromedial prefrontal cortex. This biomarker offers a new way to track patient responses to Major Depressive Disorder treatment, paving the way for individualized therapies in both intracranial and non-invasive monitoring contexts.

Influence of tree density and terrain slope on ground point density in LiDAR point clouds: a simulation-based study with Helios++

Influence of tree density and terrain slope on ground point density in LiDAR point clouds: a simulation-based study with Helios++

The VIRUS-dE Survey. II. Cuspy and Round Halos in Dwarf Ellipticals—A Result of Early Assembly?

We analyze the dark matter (DM) halos of a sample of dwarf ellipticals (dEs) and discuss cosmological and evolutionary implications. Using orbit modeling, we recover their density slopes and, for the first time, halo flattening. We find that the “cusp-core” tension is mild; on average, dEs have central slopes slightly below the Navarro–Frenk–White predictions. However, the measured flattenings are still more spherical than cosmological simulations predict. Unlike brighter early-type galaxies, the total density slopes of dEs are shallower, and their average DM density does not follow their scaling relation with luminosity. Conversely, dE halos are denser and the densities steeper than in late-type galaxies. We find average DM density and slope are strongly correlated with the environment and moderately with the angular momentum. Central, nonrotating dEs have dense and cuspy halos, whereas rotating dEs in Virgo’s outskirts are more cored and less dense. This can be explained by a delayed formation of the dEs in the cluster outskirts, or alternatively by the accumulated baryonic feedback that the dEs in the outskirts have experienced during their very different star formation history. Our results suggest halo profiles are not universal (they depend on assembly conditions) and they evolve only mildly due to internal feedback. We conclude dEs in the local Universe have assembled at a higher redshift than local spirals. In these extreme conditions, star formation and halo assembly, for example, were very different, suggesting no new dEs are formed at present.

Cathodic corrosion induced selective nano-crystallization of Nickel oxo/hydroxo complex on (NiFeCr)SiB amorphous ribbon for alkaline oxygen evolution reaction and methanol oxidation reaction

The study focuses on the development and optimization of (Ni87Fe4Cr9)78Si8B14 amorphous ribbons as self-supported electro-catalysts for oxygen evolution reaction (OER) and methanol oxidation reaction (MOR). Electro-catalytically active nano α-Ni(OH)2 phase (5–10nm) was generated in the amorphous ribbon surface through potentiostatic cathodic corrosion for different time intervals (0–120 min). The X-ray diffraction and scanning electron microscopy results shows the favourable occurrence of dense nanocrystallization of α-Ni(OH)2 between 45 and 90 min of corrosion time. For OER in 1 M KOH, the 60-min surface modified ribbon exhibits an overpotential of 295 mV at 10 mA/cm2 current density and tafel slope of 51 mV dec−1. In case of MOR in 1 M KOH +1 M MeOH, the 90-min corroded ribbon shows lowest potential of 1.38 V vs RHE, at 10 mA/cm2 and tafel slope of 34 mV dec−1. In addition to superior electro-catalytic activity, the optimal surface-modified ribbons show superior long-term stability for OER and MOR studies, indicating its potential application in hydrogen generation and direct methanol fuel cell.

An Improved Adaptive Grid-Based Progressive Triangulated Irregular Network Densification Algorithm for Filtering Airborne LiDAR Data

Ground filtering is crucial for airborne Light Detection and Ranging (LiDAR) data post-processing. The progressive triangulated irregular network densification (PTD) algorithm and its variants outperform others in accuracy, stability, and robustness, using grid-based seed point selection, TIN construction, and iterative rules for ground point identification. However, these methods still face limitations in removing low points and accurately preserving terrain details, primarily due to their sensitivity to grid size. To overcome this issue, a novel PTD filtering algorithm based on an adaptive grid (AGPTD) was proposed. The main contributions of the proposed method include an outlier removal method using a radius outlier removal algorithm and Kd-tree, a method for establishing an adaptive two-level grid based on point cloud density and terrain slope, and an adaptive selection method for angle and distance thresholds in the iterative densification processing. The performance of the AGPTD algorithm was assessed based on widely used benchmark datasets. Results show that the AGPTD algorithm outperforms the classical PTD algorithm in retaining ground feature points, especially in reducing Type I error and average total error significantly. In comparison with other advanced algorithms developed in recent years, the novel algorithm showed the lowest average Type I error, the minimal average total error, and the greatest average Kappa coefficient, which were 1.11%, 2.28%, and 90.86%, respectively. Additionally, the average accuracy, precision, and recall of AGPTD were 97.69%, 97.52%, and 98.98%, respectively.

Assessment of solitary pulmonary nodules using dual-layer spectral detector computed tomography.

We aim to quantitatively investigate the difference between benign and malignant solid pulmonary nodules that appeared on dual-energy spectral computed tomography, and assess the diagnostic accuracy of several parameters derived from computed tomography in differentiating malignant from benign pulmonary nodules. Between September 2021 and December 2022, spectral images of 71 patients (male:female = 44:27, mean age = 71.0 years) confirmed by pathology were retrospectively analyzed in the venous phase. Patients were classified into the malignant group and the benign group. The iodine concentration values of the nodules, normalized iodine concentration of the nodules to the neighboring vessels, virtual monochromatic images of 40 and 80 keV, and slope of the spectral curve were calculated and compared between the benign and malignant groups. Receiver operating characteristic curves and the area under the curve were performed to assess the diagnostic performance of the above parameters. Both virtual monochromatic images and iodine concentration maps prove to be highly useful in differentiating benign and malignant pulmonary nodules. The malignant pulmonary nodules have higher iodine density and slope of the spectral curve than the benign lesions. The combined model of iodine density and curve slope with an optimal cutoff of 0.39 (area under the curve = 0.82) yielded a sensitivity of 95% and a specificity of 63%. Contrast-enhanced dual-energy spectral computed tomography allows promising capability of distinguishing malignant from benign lesions, potential for avoiding unnecessary invasive procedure or surgery.

Assessment of Wind Energy Potential and Optimal Site Selection for Wind Energy Plant Installations in Igdir/Turkey

Wind energy is an eco-friendly, renewable, domestic, and infinite resource. These factors render the construction of wind turbines appealing to nations, prompting numerous governments to implement incentives to augment their installed capacity of wind turbines. Alongside augmenting the installed capacity of wind turbines, identifying suitable locations for their installation is crucial for optimizing turbine performance. This study aims to evaluate potential sites for wind power plant installation via a GIS, a mapping technique. The Analytic Hierarchy Process (AHP) was employed to assess the locations, including both quantitative and qualitative aspects that significantly impact the wind farm suitability map. Utilizing the GIS methodology, all datasets were examined through height and raster transformations of land surface temperature, plant density index, air pressure, humidity, wind speed, air temperature, land cover, solar radiation, aspect, slope, and topographical characteristics, resulting in the creation of a wind farm map. The correlation between the five-year meteorological data and environmental parameters (wind direction, daily wind speed, daily maximum and minimum air temperatures, daily relative humidity, daily average air temperature, solar radiation duration, daily cloud cover, air humidity, and air pressure) influencing the wind power plant in Iğdır province, including Iğdır Airport, Karakoyunlu, Aralık, and Tuzluca districts, was analyzed. If wind energy towers are installed at 1 km intervals across an area of roughly 858,180 hectares in Igdir province, an estimated 858,180 GWh of wind energy can be generated. The GIS-derived wind power plant map indicates that the installation sites for wind power plants are located in regions susceptible to wind erosion.

Integrated geophysical and GIS approaches for groundwater potential assessment: a case study of Aladja, Delta State, Nigeria

ABSTRACT This study explores the groundwater potential in Aladja, Udu, Local Government Area of Delta State, Nigeria, using an integrated approach combining electrical resistivity techniques with Remote Sensing (RS) and Geographic Information System (GIS) methods. The primary aim is to delineate aquifers and comprehensively assess groundwater resources. Methods include Vertical Electrical Sounding (VES) to gather resistivity data, RS and GIS for analyzing geological and hydrological parameters such as lineament density, drainage density, slope, soil type, and land use. The resistivity values ranged from 147 to 460.50 Ωm, with aquifer thicknesses varying between 6.50 and 36.30 m. The RS and GIS analysis indicated high groundwater potential in regions characterized by significant lineament density and moderate slopes. The study highlights the complementarity of VES and RS/GIS in groundwater exploration, revealing substantial groundwater resources in the northwestern regions of the study area. This approach underscores the importance of integrating these methods for a more accurate assessment of groundwater potential. The novelty of this study lies in validating RS and GIS findings with VES data, ensuring reliable groundwater potential mapping and effective resource management. This integrated methodology offers a robust framework for sustainable groundwater resource assessment and management in similar geological settings.

Sparkling Synergy: Enhancing Hydrogen Evolution with a Mesoporous CoP/FeP Interface.

The reaction kinetics is predominantly determined by the surface and interface engineering of electrocatalysts. Herein, we demonstrate the growth of cobalt monophosphide and iron monophosphide (CoP/FeP) with an effective solid interface. The surface of CoP/FeP is mesoporous, which is obtained by phosphidizing mesoporous CoFe2O4. The CoP/FeP electrode exhibits substantially superior hydrogen evolution reaction (HER) performance compared to CoP and FeP. The overpotentials (η) required to generate 10 mA cm-2 are determined to be around 98 mVRHE (CoP/FeP), 220 mVRHE (FeP), and 265 mVRHE (CoP) in an acidic electrolyte. The exchange current density and Tafel slopes suggest that CoP/FeP has better redox properties and kinetic abilities compared to FeP and CoP. Furthermore, the CoP/FeP electrode exhibits reduced electrochemical impedance and superior surface charge transport characteristics in comparison to both the CoP and FeP electrodes. In addition to having a greater number of catalytically active sites, the turnover frequency of CoP/FeP is approximately 2 and 5 times higher than that of FeP and CoP, respectively. The CoP/FeP electrode maintains a consistent current density of around 25 mA cm-2 for a continuous period of 24 h during the HER, attesting to the excellent durability of the CoP/FeP electrode. In addition, a relationship between differential hydrogen adsorption energy (ΔEH), the corresponding Gibbs free energy change (ΔGH), and the hydrogen coverage on distinct surfaces, namely, CoP, FeP, and CoP/FeP, is established. The calculation findings show that the CoP/FeP surface, which is predominantly exposed with CoP, exhibits the highest catalytic potential for the HER. The estimation of the specific HER activity of the electrodes, normalized to the electrochemically active surface area, corroborates the calculation findings.

Electrochemical noise characterization of corrosion behavior for NiCrAl-NiC coating

The electrochemical noise analysis (including frequency domain and wavelet analyses) method is used to characterize the corrosion behavior of NiCrAl-NiC Abradable Seal Coating (ASC) at different immersion times. By converting EN data to frequency domain analysis, the slope (k values) of current power spectral density (PSD) curves of NiCrAl-NiC ASC increases with prolonged immersion time, suggesting a transition from localized corrosion to pitting. Wavelet analysis results indicate that the D7-D8 detail coefficients control the wavelet energy throughout the immersion process, and with increasing immersion time, the electrochemical activity on the NiCrAl-NiC ASC surface decreases. The electrochemical noise analysis can effectively explain the corrosion behaviors of NiCrAl-NiC ASC.

The SLACS strong lens sample, debiased

Strong gravitational lensing observations can provide extremely valuable information on the structure of galaxies, but their interpretation is made difficult by selection effects, which, if not accounted for, introduce a bias between the properties of strong lens galaxies and those of the general population. A rigorous treatment of the strong lensing bias requires, in principle, to fully forward model the lens selection process. However, doing so for existing lens surveys is prohibitively difficult. With this work we propose a practical solution to the problem: using an empirical model to capture the most complex aspects of the lens finding process, and constraining it directly from the data together with the properties of the lens population. We applied this method to real data from the SLACS sample of strong lenses. Assuming a power-law density profile, we recovered the mass distribution of the parent population of galaxies from which the SLACS lenses were drawn. We found that early-type galaxies with a stellar mass of log M*/M⊙ = 11.3 and average size have a median projected mass enclosed within a 5 kpc aperture of log M5/M⊙ = 11.332 ± 0.013, and an average logarithmic density slope of γ = 1.99 ± 0.03. These values are respectively 0.02 dex and 0.1 lower than inferred when ignoring selection effects. According to our model, most of the bias is due to the prioritisation of SLACS follow-up observations based on the measured velocity dispersion. As a result, the strong lensing bias in γ reduces to ∼0.01 when controlling for stellar velocity dispersion.

Mapping the anisotropic Galactic stellar halo with blue horizontal branch stars

We used Legacy Survey photometric data to probe the stellar halo in multiple directions of the sky using a probabilistic methodology to identify blue horizontal branch (BHB) stars. The measured average radial density profile follows a double power law in the range 5 < rgc/kpc < 120, with a density break at rgc ≈ 20 kpc. This description, however, falls short, depending on the chosen line of sight, with some regions showing no signature of a break in the profile and a wide range of density slopes, such as an outer slope −5.5 ≲ αout ≲ −4, pointing towards a highly anisotropic stellar halo. This explains, in part, the wide range of density profiles reported in the literature owing to different tracers and sky coverage. Using our detailed 3D stellar halo density map, we quantified the shape of the Pisces overdensity associated with the transient wake response of the Galaxy’s (dark) halo to the Large Magellanic Cloud (LMC). Measured in the LMC’s coordinate system, Pisces stands above the background, is 60° long and 25° wide, and is aligned with the LMC’s orbit. This would correspond to a wake width of ∼32 kpc at ∼70 kpc. We do not find a statistically significant signature of the collective response in density as previously reported in the literature measured with K giant stars, despite our larger numbers. We release the catalogue constructed in this study with 95 446 possible BHB stars and their BHB probability.

Geospatial and geo-electrical assessment of groundwater vulnerability and potential in parts of Cross River, Southern Nigeria

Assessing groundwater vulnerability and potential is essential for sustainable management. This study evaluates these factors in southern Cross River, Nigeria, using geospatial and geo-electrical methods, including Vertical Electrical Sounding (VES), Geographic Information Systems (GIS), and Remote Sensing (RS). Twenty VES surveys were performed, revealing aquifer resistivity from 5.12 to 506.00 Ω/m, thickness from 6.60 to 34.30 m, and depth from 18.60 to 68.00 m. Rainfall was the most significant factor (38 %) affecting groundwater potential, followed by geology (24 %), slope (13 %), drainage density (8 %), land use/cover (6 %), lineament density (5 %), and soil type (3 %). With a Consistency Ratio (CR) of 0.043884, data consistency was high. Groundwater potential zoning (GWPZ) maps categorized the area into low, moderate, good, and excellent zones, highlighting high potential in western areas with high lineament density and moderate slopes. This research demonstrates the effectiveness of integrating geospatial and geo-electrical techniques for groundwater assessment.

Parametric Analysis of Indium Gallium Arsenide Wafer-based Thin Body (5 nm) Double-gate MOSFETs for Hybrid RF Applications.

The electrical behavior of a high-performance Indium Gallium Arsenide (In- GaAs) wafer-based n-type Double-Gate (DG) MOSFET with a gate length (LG1= LG2) of 2 nm was analyzed. The relationship of channel length, gate length, top and bottom gate oxide layer thickness, a gate oxide material, and the rectangular wafer with upgraded structural characteristics and the parameters, such as switch current ratio (ION/IOFF) and transconductance (Gm) was analyzed for hybrid RF applications. This work was carried out at 300 K utilizing a Non-Equilibrium Green Function (NEGF) mechanism for the proposed DG MOSFET architecture with La2O3 (EOT=1 nm) as gate dielectric oxide and source-drain device length (LSD) of 45 nm. It resulted in a maximum drain current (IDmax) of 4.52 mA, where the drain-source voltage (VDS) varied between 0 V and 0.5 V at the fixed gate to source voltage (VGS) = 0.5 V. The ON current(ION), leakage current (IOFF), and (ION/IOFF) switching current ratios of 1.56 mA, 8.49Í10-6 μA, and 18.3Í107 μA were obtained when the gate to source voltage (VGS) varied between 0 and 0.5 V at fixed drain-source voltage (VDS)=0.5V. The simulated result showed the values of maximum current density (Jmax), one and twodimensional electron density (N1D and N2D), electron mobility (μn), transconductance (Gm), and Subthreshold Slope (SS) are 52.4 μA/m2, 3.6Í107 cm-1, 11.36Í1012 cm-2, 1417 cm2V-1S-1, 3140 μS/μm, and 178 mV/dec, respectively. The Fermi-Dirac statistics were employed to limit the charge distribution of holes and electrons at a semiconductor-insulator interface. The flat-band voltage (VFB) of - 0.45 V for the fixed threshold voltage greatly impacted the breakdown voltage. The results were obtained by applying carriers to the channels with the (001) axis perpendicular to the gate oxide. The sub-band energy profile and electron density were well implemented and derived using the Non-Equilibrium Green's Function (NEGF) formalism. Further, a few advantages of the proposed heterostructure-based DG MOSFET structure over the other structures were observed. This proposed patent design, with a reduction in the leakage current characteristics, is mainly suitable for advanced Silicon-based solid-state CMOS devices, Microelectronics, Nanotechnologies, and future-generation device applications.

El Gordo needs El Anzuelo: Probing the structure of cluster members with multi-band extended arcs in JWST data

Gravitational lensing by galaxy clusters involves hundreds of galaxies over a large redshift range and increases the likelihood of rare phenomena (supernovae, microlensing, dark substructures, etc.). Characterizing the mass and light distributions of foreground and background objects often requires a combination of high-resolution data and advanced modeling techniques. We present the detailed analysis of a prominent quintuply imaged dusty star-forming galaxy ($ mainly lensed by three members of the massive galaxy cluster ACT-CL\,J0102$-$4915, also known as d =0.87$). We leverage JWST/NIRCam images, which contain lensing features that were unseen in previous HST images, using a Bayesian, multi-wavelength, differentiable and GPU-accelerated modeling framework that combines (lens modeling) and (field model and inference) software packages. For one of the deflectors, we complement lensing constraints with stellar kinematics measured from VLT/MUSE data. In our lens model, we explicitly include the mass distribution of the cluster, locally corrected by a constant shear field. We find that the two main deflectors (L1 and L2) have logarithmic mass density slopes steeper than isothermal, with $ L1 and $ L2 We argue that such steep density profiles can arise due to tidally truncated mass distributions, which we probe thanks to the cluster lensing boost and the strong asymmetry of the lensing configuration. Moreover, our three-dimensional source model captures most of the surface brightness of the lensed galaxy, revealing a clump with a maximum diameter of $400$ parsecs at the source redshift, visible at wavelengths $ rest mu m. Finally, we caution on using point-like features within extended arcs to constrain galaxy-scale lens models before securing them with extended arc modeling.

An efficient multifunctional SnS2/g-C3N4 hierarchical nanoflower catalyst for electrocatalytic and photocatalytic applications

The rising energy demand via renewable sources and existence of organic pollutants in water has attracted the world-wide attention to attain sustainable ecosystems. The development of a multi-functional catalyst with significant economic and environmental implications remains a challenge. Herein, we synthesized SnS2/g-C3N4 hierarchical nanoflower using solvothermal method, verified by XRD and FTIR investigations. The surface morphology was analyzed using FESEM, TEM and HRTEM while optical absorption via UV–Vis spectroscopy. SnS2/g-C3N4 displayed outstanding electrocatalytic activity for HER and OER with smaller tafel slope and higher values of current density. The results are in accordance with Cdl and ECSA values, ensuing more active sites and surface area for a catalytic reaction to take place. As-prepared SnS2/g-C3N4 also exhibited 90 % photocatalytic MB deterioration in 90 min upon solar irradiation, following first order kinetics. Type-II mechanism for charge transfer alongwith reactive specie trapping experiment and cyclic stability is also presented. The findings suggests that SnS2/g-C3N4 emerged as proficient catalyst for electrocatalytic and photocatalytic applications.

HSTPROMO Internal Proper-motion Kinematics of Dwarf Spheroidal Galaxies. I. Velocity Anisotropy and Dark Matter Cusp Slope of Draco

We analyze four epochs of Hubble Space Telescope imaging over 18 yr for the Draco dwarf spheroidal galaxy. We measure precise proper motions for hundreds of stars and combine these with existing line-of-sight (LOS) velocities. This provides the first radially resolved 3D velocity dispersion profiles for any dwarf galaxy. These constrain the intrinsic velocity anisotropy and resolve the mass–anisotropy degeneracy. We solve the Jeans equations in oblate axisymmetric geometry to infer the mass profile. We find the velocity dispersion to be radially anisotropic along the symmetry axis and tangentially anisotropic in the equatorial plane, with a globally averaged value βB¯=−0.20−0.53+0.28 , (where 1 – βB≡〈vtan2〉/〈vrad2〉 in 3D). The logarithmic dark matter (DM) density slope over the observed radial range, Γdark, is −0.83−0.37+0.32 , consistent with the inner cusp predicted in ΛCDM cosmology. As expected given Draco’s low mass and ancient star formation history, it does not appear to have been dissolved by baryonic processes. We rule out cores larger than 487, 717, and 942 pc at 1σ, 2σ, and 3σ confidence, respectively, thus imposing important constraints on the self-interacting DM cross section. Spherical models yield biased estimates for both the velocity anisotropy and the inferred slope. The circular velocity at our outermost data point (900 pc) is 24.19−2.97+6.31kms−1 . We infer a dynamical distance of 75.37−4.00+4.73 kpc and show that Draco has a modest LOS rotation, with v/σ=0.22±0.09 . Our results provide a new stringent test of the so-called “cusp–core” problem that can be readily extended to other dwarfs.

Oceanic Fronts Driven by the Amazon Freshwater Plume and Their Thermohaline Compensation at the Submesoscale

AbstractUpper ocean fronts are dynamically active features of the global ocean playing a key role in the air‐sea exchanges of properties and their transport in the ocean interior. With scales ranging from the submesoscale (0.1–10 km) to the mesoscale (10–100s km) and a temporal variability from hours to months, collecting in situ observations of these structures is challenging and this has limited our understanding of their associated processes and impacts. During the EUREC4A‐OA/ATOMIC field experiment, which took place in the northwest tropical Atlantic in January–February 2020, a large number of uncrewed platforms, including five Saildrones, were deployed to provide a detailed picture of the upper‐ocean fine‐scale variability. This region is strongly influenced by the outflow of the Amazon River, even in winter, which is the minimum outflow season. Here, the generation of fine‐scale horizontal thermohaline gradients is driven by the stirring of this freshwater river input by large anticyclonic eddies, the so‐called North Brazil Current Rings. Vertical shear estimates using the Saildrones ADCP show that partial temperature compensation occurs along restratifying submesoscale salinity‐dominated fronts. The distribution of surface along‐track gradients, as sampled by different horizontal length‐scales, reveals the prevalence of submesoscale fronts. This is supported by a flattening of the spectral slopes of surface density at the submesoscale. This study emphasizes the need to resolve the upper ocean at high spatial resolution to understand its impact on the broader circulation and to properly represent air‐sea interactions.

Dark Matter halo parameters from overheated exoplanets via Bayesian hierarchical inference

Dark Matter (DM) can become captured, deposit annihilation energy, and hence increase the heat flow in exoplanets and brown dwarfs. Detecting such a DM-induced heating in a population of exoplanets in the inner kpc of the Milky Way thus provides potential sensitivity to the galactic DM halo parameters. We develop a Bayesian Hierarchical Model to investigate the feasibility of DM discovery with exoplanets and examine future prospects to recover the spatial distribution of DM in the Milky Way. We reconstruct from mock exoplanet datasets observable parameters such as exoplanet age, temperature, mass, and location, together with DM halo parameters, for representative choices of measurement uncertainty and the number of exoplanets detected. We find that detection of ℴ(100) exoplanets in the inner Galaxy can yield quantitative information on the galactic DM density profile, under the assumption of 10% measurement uncertainty. Even as few as ℴ(10) exoplanets can deliver meaningful sensitivities if the DM density and inner slope are sufficiently large.https://github.com/mariabenitocst/exoplanets

Thermoelectric performance of Ag2GeX3 (X = S, Se, Te) with intrinsically low lattice thermal conductivity: A first principles study

Low lattice thermal conductivity is one of the key factor for excellent thermoelectric performance of materials. In this work, we have systematically studied the thermoelectric properties of Ag2GeX3 (X = S, Se, Te) by first-principles calculations in combination with Boltzmann transport theory. In terms of phonon transmission performance, due to the low frequency of acoustic phonons, strong coupling between low-frequency optical phonons and acoustic phonons, and relatively strong anharmonicity, Ag2GeX3 (X = S, Se, Te) exhibits extremely low lattice thermal conductivity of 0.30 Wm−1K−1, 0.28 Wm−1K−1 and 0.65 Wm−1K−1 at room temperature, respectively. At the same time, Ag2GeX3 (X = S, Se, Te) also exhibits good electrical transport performance. The appropriate band gap and high slope of electronic density of states (DOS) near the Fermi level result in a large Seebeck coefficient of the materials. As a result, the optimal ZT values of p(n)-type Ag2GeX3 (X = S, Se, Te) are 1.4(1.2), 2.2(0.7), and 0.9(0.7) at 800 K, respectively. These results demonstrate outstanding thermoelectric performance of Ag2GeSe3 for energy conversion applications.