Wave Approach Research Articles

Engineering optoelectronic properties of [formula omitted] superlattices using first principles method

Recent advancements in thin-film growth techniques have opened doors for engineering innovative heterostructures with ultra-thin layers. These artificial superlattices hold promise for novel optoelectronic devices. However, a complete understanding of their properties is crucial for optimal design. In this study, we employ the full-potential linearized augmented plane wave (FP−LAPW) approach based on density functional theory (DFT) to engineer the optoelectronic properties of (HgSe)n/(ZnTe)n superlattices by controlling the number of layers (n) in SLs; The exchange-correlation potential was calculated by the generalized gradient GGA approximation and the optoelectronics properties has adjusted by the Tran-Blaha modified Becke-Johnson (TB−mBJ) correction of GGA approximation. Our findings shed light on the significant influence of stacking periodicity on the optoelectronic properties of HgTe/ZnTe SLs. We demonstrate that manipulating layer count is a viable strategy for engineering their optoelectronic characteristics. Additionally, the predicted near-infrared absorption makes these SLs promising candidates for near-infrared detector applications.

Electronic and optical characteristics of CaLiX3 (X = Cl, Br, I) perovskite compounds using the Tran–Blaha modified Becke–Johnson potential

We present the results of a comprehensive investigation using the full-potential linearized augmented plane wave approach to analyze the structural characteristics, electronic structures, and optical spectra of the perovskite compounds CaLiX3 (X = Cl, Br, or I). Various functionals were employed to simulate the exchange–correlation interactions. The calculated equilibrium structural parameters, obtained using the generalized gradient approximation, are consistent with the existing findings in the literature. The computed electronic structures reveal that the Tran–Blaha modified Becke–Johnson potential significantly enhances the bandgap. For all CaLiX3 compounds studied, we predicted an indirect bandgap. Additionally, we observed a gradual decrease in the bandgap as the atomic size of the X element increases. The electronic states constituting the various energy bands were evaluated by computing the partial and total densities of states. In addition, we computed a variety of optical spectra, including the complex dielectric function, absorption coefficient, refractive index, extinction coefficient, reflectivity, and electron energy loss function. The results demonstrate that a decrease in the bandgap leads to an increase in the zero-frequency limit of the dielectric function ε(0). The origins of the peaks and structures in the optical spectra were identified.

Cognitive behavioural therapy and third-wave approaches for anxiety and related disorders in older people.

Cognitive behavioural therapy (CBT) is the most researched psychological therapy for anxiety disorders in adults, and known to be effective in this population. However, it remains unclear whether these results apply to older adults, as most studies include participants between 18 and 55 years of age. This systematic review aims to provide a comprehensive and up-to-date synthesis of the available evidence on CBT and third wave approaches for older adults with anxiety and related disorders. To assess the effects of Cognitive Behavioural Therapy (CT, BT, CBT and third-wave CBT interventions) on severity of anxiety symptoms compared with minimal management (not providing therapy) for anxiety and related disorders in older adults, aged 55 years or over. To assess the effects of CBT and related therapies on severity of anxiety symptoms compared with other psychological therapies for anxiety and related disorders in older adults, aged 55 years or over. We searched the Cochrane Common Mental Disorders Controlled studies Register (CCMDCTR), CENTRAL, Ovid MEDLINE, Ovid Embase and Ovid PsycINFO to 21 July 2022. These searches were updated on 2 February 2024. We also searched the international studies registries, including Clinicalstudies.gov and the WHO International Clinical Trials Registry Platform (ICTRP), to identify additional ongoing and unpublished studies. These sources were manually searched for studies up to 12 February 2024. We included randomised controlled trials (RCTs) in older adults (≥ 55 years) with an anxiety disorder, or a related disorder, including obsessive compulsive disorder (OCD), acute stress disorder and post-traumatic stress disorder (PTSD), that compared CBT to either minimal management or an active (non-CBT) psychological therapy. Eligible studies had to have an anxiety-related outcome. Several authors independently screened all titles identified by the searches. All full texts were screened for eligibility according to our prespecified selection criteria. Data were extracted and the risk of bias was assessed using the Cochrane tool for RCTs. The certainty of evidence was evaluated using GRADE. Meta-analyses were performed for outcomes with quantitative data from more than one study. We included 21 RCTs on 1234 older people allocated to either CBT or control conditions. Ten studies focused on generalised anxiety disorder; others mostly included a mix of clinical diagnoses. Nineteen studies focused on the comparison between CBT and minimal management. Key issues relating to risk of bias were lack of blinding of participants and personnel, and participants dropping out of studies, potentially due to treatment preference and allocation. CBT may result in a small-to-moderate reduction of anxiety post-treatment (SMD -0.51, 95% CI -0.66 to -0.36, low-certainty evidence). However, compared to this benefit with CBT immediately after treatment, at three to six months post-treatment, there was little to no difference between CBT and minimal management (SMD -0.29, 95% CI -0.59 to 0.01, low-certainty evidence). CBT may have little or no effect on clinical recovery/ improvement post-treatment compared to minimal management, but the evidence is very uncertain (RR 1.56, 95% CI 1.20 to 2.03, very low-certainty evidence). Results indicate that five people would need to receive treatment for one additional person to benefit (NNTB = 5). Compared to minimal management, CBT may result in a reduction of comorbid depression symptoms post-treatment (SMD -0.57, 95% CI -0.74 to -0.40, low-certainty evidence). There was no difference in dropout rates post-treatment, although the certainty of the evidence was low (RR 1.19, 95% CI 0.80 to 1.78). Two studies reported adverse events, both of which related to medication in the control groups (very low-certainty evidence, no quantitative estimate). Only two studies compared CBT to other psychological therapies, both of which only included participants with post-traumatic stress disorder. Low-certainty evidence showed no difference in anxiety severity post-treatment and at four to six months post-treatment, symptoms of depression post-treatment, and dropout rates post-treatment. Other outcomes and time points are reported in the results section of the manuscript. CBT may be more effective than minimal management in reducing anxiety and symptoms of worry and depression post-treatment in older adults with anxiety disorders. The evidence is less certain longer-term and for other outcomes including clinical recovery/improvement. There is not enough evidence to determine whether CBT is more effective than alternative psychological therapies for anxiety in older adults.

Cognitive behavioural therapy and third-wave approaches for anxiety and related disorders in older people.

Cognitive behavioural therapy (CBT) is the most researched psychological therapy for anxiety disorders in adults, and known to be effective in this population. However, it remains unclear whether these results apply to older adults, as most studies include participants between 18 and 55 years of age. This systematic review aims to provide a comprehensive and up-to-date synthesis of the available evidence on CBT and third wave approaches for older adults with anxiety and related disorders. To assess the effects of Cognitive Behavioural Therapy (CT, BT, CBT and third-wave CBT interventions) on severity of anxiety symptoms compared with minimal management (not providing therapy) for anxiety and related disorders in older adults, aged 55 years or over. To assess the effects of CBT and related therapies on severity of anxiety symptoms compared with other psychological therapies for anxiety and related disorders in older adults, aged 55 years or over. We searched the Cochrane Common Mental Disorders Controlled studies Register (CCMDCTR), CENTRAL, Ovid MEDLINE, Ovid Embase and Ovid PsycINFO to 21 July 2022. These searches were updated on 2 February 2024. We also searched the international studies registries, including Clinicalstudies.gov and the WHO International Clinical Trials Registry Platform (ICTRP), to identify additional ongoing and unpublished studies. These sources were manually searched for studies up to 12 February 2024. We included randomised controlled trials (RCTs) in older adults (≥ 55 years) with an anxiety disorder, or a related disorder, including obsessive compulsive disorder (OCD), acute stress disorder and post-traumatic stress disorder (PTSD), that compared CBT to either minimal management or an active (non-CBT) psychological therapy. Eligible studies had to have an anxiety-related outcome. Several authors independently screened all titles identified by the searches. All full texts were screened for eligibility according to our prespecified selection criteria. Data were extracted and the risk of bias was assessed using the Cochrane tool for RCTs. The certainty of evidence was evaluated using GRADE. Meta-analyses were performed for outcomes with quantitative data from more than one study. We included 21 RCTs on 1234 older people allocated to either CBT or control conditions. Ten studies focused on generalised anxiety disorder; others mostly included a mix of clinical diagnoses. Nineteen studies focused on the comparison between CBT and minimal management. Key issues relating to risk of bias were lack of blinding of participants and personnel, and participants dropping out of studies, potentially due to treatment preference and allocation. CBT may result in a small-to-moderate reduction of anxiety post-treatment (SMD -0.51, 95% CI -0.66 to -0.36, low-certainty evidence). However, compared to this benefit with CBT immediately after treatment, at three to six months post-treatment, there was little to no difference between CBT and minimal management (SMD -0.29, 95% CI -0.59 to 0.01, low-certainty evidence). CBT may have little or no effect on clinical recovery/ improvement post-treatment compared to minimal management, but the evidence is very uncertain (RR 1.56, 95% CI 1.20 to 2.03, very low-certainty evidence). Results indicate that five people would need to receive treatment for one additional person to benefit (NNTB = 5). Compared to minimal management, CBT may result in a reduction of comorbid depression symptoms post-treatment (SMD -0.57, 95% CI -0.74 to -0.40, low-certainty evidence). There was no difference in dropout rates post-treatment, although the certainty of the evidence was low (RR 1.19, 95% CI 0.80 to 1.78). Two studies reported adverse events, both of which related to medication in the control groups (very low-certainty evidence, no quantitative estimate). Only two studies compared CBT to other psychological therapies, both of which only included participants with post-traumatic stress disorder. Low-certainty evidence showed no difference in anxiety severity post-treatment and at four to six months post-treatment, symptoms of depression post-treatment, and dropout rates post-treatment. Other outcomes and time points are reported in the results section of the manuscript. CBT may be more effective than minimal management in reducing anxiety and symptoms of worry and depression post-treatment in older adults with anxiety disorders. The evidence is less certain longer-term and for other outcomes including clinical recovery/improvement. There is not enough evidence to determine whether CBT is more effective than alternative psychological therapies for anxiety in older adults.

An in-depth look at the stability, electronic structure, mechanical properties, and thermodynamics characteristic of Ir3TM (TM: Sc, Ti, V) compounds

In this paper, the structural, mechanical, electronic, and thermodynamic properties of Ir3TM (TM = Sc, Ti, and V) intermetallic compounds in the cubic (L12) and hexagonal (D019 and D024) phases are presented. The outcomes of the simulation rely on density functional theory (DFT) within the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) based on the full-potential linearized augmented plane wave (FP-LAPW) approach. The existing study was performed on the L12 cubic phase. in addition to hexagonal D024 and D019 phases, which may be relative but differ in the way that the atomic layers are stacked. The calculated total, cohesive energy, and heat formation suggest that the Ir3Sc compound can be stable in the D024 phase because of an overlap between the L12 and D024 phases with a total energy difference of around 0.026 eV/atom. Ir3Ti and Ir3V are more stable in L12 and D019, respectively. From elastic constants calculations, it reveals that the studied compounds are mechanically stable and harder in the cubic phase than hexagonal phase. However, Ir3Sc has the lowest hardness due to its relative ductility. Inversely, Ir3V has the maximum hardness with a lack of ductility. It was observed that these compounds have an elastic anisotropy based on the three-dimensional Young's modulus surface, and Ir3Sc has the strongest anisotropy, while Ir3V has the weakest in the L12 phase. The total density of state (TDOS) calculations shows that Ir3Ti and Ir3V are stable in the L12 and D019 phases, respectively, except for the Ir3Sc compound which might undergo a martensitic transition. Also, the pseudogap for Ir3V moves quite close to the Fermi level, indicating that the covalent bonding in this compound is sharper than the other compounds. Moreover, via the quasi-harmonic Debye model within the Gibbs computational code, thermodynamic properties are calculated and analyzed with temperature and pressure.

Spin-polarized electronic, optical, and transport properties of novel Cs2XMoBr6 (X=Na, Li) HDPs: First-principles study

We explored the electronic, optical, and thermoelectric characteristics of novel Cs2XMoBr6 (X=Na, Li) halide-based double perovskites (HDPs) in their monoclinic phase using the density functional theory (DFT). The full-potential linearized augmented plane wave approach was used in the present work. The material Cs2NaMoBr6 was noticed as half-metallic as indicated by an indirect band gap semiconducting nature in the spin-down channel, and with a metallic nature in the spin-up channel. Similarly, the Cs2LiMoBr6 material also revealed a half-metallic nature with an indirect band gap semiconducting nature in spin-down mode and a metallic behavior in spin-up mode. The density of states analysis verifies the electronic behavior of these compounds. To determine the optical characteristics, the optical parameters such as the dielectric functions, the absorption coefficients, the refractivity, the energy loss function, and the reflectivity, have been described. The thermoelectric characteristics of the compounds along the temperature are calculated. It was confirmed that these materials possess extraordinary characteristics that would make them excellent options for influential electronic, optical, and thermoelectric, device applications.

Novel Ternary Halide Perovskites - CaKI3 and CaRbI3 : Investigation of structural, electronic and optical properties for optoelectronic applications.

The full-potential linearized augmented plane wave approach is used in this work to investigate the structural, electronic, elastic, thermal, and optical properties of CaKI3 and CaRbI3 cubic perovskite compounds using GGA_PBE and TB_mBJ approximations. The structures have been relaxed and ground state structural parameters are calculated. Density of states calculated reveal narrow band gaps which are around Schockley-Queisser limit(Eg≈1.34 eV). Optical characteristics imply that CaKI3 may be more appropriate for solar cell applications than CaRbI3.

Lattice Boltzmann simulation of breaking waves

Water wave breaking at the ocean’s surface is a turbulent phenomenon and encompasses a wide range of physical processes such as generation of bubbles/drops with different spatio-temporal scales. In the present study, breaking of periodic waves in deep water regime has been simulated using phase-field lattice Boltzmann method (LBM). Compared to direct Navier–Stokes equation based numerical models, the present LB model is Poisson-free and explicit in time integration. Both the flow field and interface are solved using LBM with two sets of distribution functions. The normalized pressure-velocity formulation is used for the flow field, whereas the conservative Allen–Cahn equation is used to capture the interface. An impulsively started wave approach with Stokes third order wave profile has been used to initiate the breaking process. Through systematic variation of Weber number and initial steepness, the effect of surface tension on the kinematic, geometric, and energy dissipation characteristics has been studied for three breaker types, viz., spilling, weak plunging, and plunging breakers. The results are in good agreement with the past experimental observations and direct numerical simulation. In particular, the obtained breaking strength for different Weber numbers agrees well with the semi-empirical relation used in a wind-wave forecasting models.

Exploring the Mn doped BaTe alloy for spintronics and energy harvesting applications

In the present study, the ferromagnetic semiconductor behavior of Mn doped BaTe is reported along with their physical properties. The calculations are done by full potential linearized augmented plane wave (FP-LAPW) approach within spin-polarized density functional theory (SP-DFT). Formation energies were computed to satisfy the stability of reported alloys. The spin-polarization is included in the calculations to study the electronic (band structure (BS), density of states (DOS)) and magnetic characteristics. Ba1−xMnxTe elucidates the magnetic semiconductor nature with direct band gap (Eg) in both spin channels while indirect Eg (1.66 eV) is observed for pure BaTe compound. Stable ferromagnetic (FM) states are vindicated owing to the p-d hybridization which are contributors in inducing magnetic moments (μ B) at interstitial and non-magnetic sites. The optical parameters (reflectivity, absorption coefficient, refraction, optical conductivity and dielectric function) were computed within an energy range of 0–10 eV. Thermoelectric (TE) features are also figured using Boltaz-Trap code in terms of thermal and electrical conductivity, figure of merit, Seebeck coefficient and power factor. The analysis of optical parameters suggests that the considered alloys is active within visible to UV-range, having potential applications in optoelectronic, photovoltaic and thermoelectric applications.

Exploring ZnFeSnO4 double spinel: A thorough investigation of mechanical, dynamical, magneto-electronic properties and lattice thermal conductivity

Double spinel materials ABB'O4 emerge as an innovative class of oxides with promising technological applications. First-principles calculations are employed to explore the fundamental properties of the double spinel ZnFeSnO4. Its elasticity and dynamic stability are investigated using the pseudo-potential plane wave (PP-PW) method, while the full-potential linearized augmented plane wave (FP-LAPW) approach is used to study its electronic and magnetic properties. The results reveal favorable thermodynamic stability, mechanical robustness, and dynamical stability for ZnFeSnO4. Analysis using GGA + U (U = 6 eV) in the FP-LAPW framework predicts half-metallic ferromagnetism, a highly desirable characteristic for spintronic applications due to its potential spin-polarized currents. However, the use of the mBJ functional results in semiconducting character with bandgaps of 1.813 eV, and 1.524 eV for spin-up and spin-down, respectively. Hence, the outcomes of the computations pertaining to the electronic characteristics are contingent upon the selection of the exchange-correlation functional. Furthermore, the calculated low lattice thermal conductivity of ZnFeSnO4 indicates its potential suitability for thermoelectric applications.

Analysis of structural, electronic and optical properties of Er-doped rock salt AlN using ab-initio calculations.

This investigation includes the structural and optoelectronic characteristics of both pure and Er-doped rock salt aluminium nitride (AlN). Upon introducing Er doping into the AlN host, the calculations reveal a rise in the atomic parameter. Incorporating Er into the system leads to enhancements in the static dielectric coefficient ɛ1(0), static reflectivity R(0), as well as static refractive index n(0), at zero frequency. After doping, the peaks of imaginary dielectric tensor, extinction coefficient and absorption coefficient shift towards lower energy levels. Various exchange correlation potentials are incorporated to compare the results of electronic and optical characteristics. We employed the full potential linearized augmented plane wave (FP-LAPW) approach with WIEN2k code in conjunction with the density functional theory (DFT). To explore the optoelectronic characteristics of both pure as well as doped systems, three distinct exchange correlation potentials are utilized: the Perdew-Burke-Ernzerhof Generalized Gradient Approximation (PBE-GGA), Modified Becke Johnson Generalized Gradient Approximations (mBJ + GGA) and Hubbard potential (GGA + U).

Vibrating roller with compacted soil interaction modelling

Introduction. Vibrating rollers are the most common means of compacting soils in construction. The nature of stress development on the contact surface of the roller with the ground depends on the technical characteristics of the vibrating roller (the mass of the roller, the mass of the roller frame, the frequency and driving force of vibrations, the number and characteristics of the roller shock absorbers) and the properties of the soil.Materials and methods. Simulation of the interaction of a vibrating roller with compacted soil was carried out using a three-mass rheological model of the frame-roller-soil system. Differential equations of mass motion in contact and separation modes were solved numerically. To determine the numerical values of the loading time (increase in contact stresses from zero to the maximum value) and the unloading time (decrease in contact stresses from the maximum value to zero), as well as the maximum reaction force of the soil, a computational experiment was conducted on a rheological model. The mass of the vibrating roller module (the mass of the front axle) and the relative driving force were used as independent parameters of the vibrating roller. The coefficients of elastic and viscous resistance of the soil were chosen as independent parameters of the soil. The total number of combinations of factors was 192. The values of the time of loading and unloading of the soil, as well as the maximum strength of the soil reaction, were determined by oscillograms of changes in the strength of the soil reaction over time.Results. Using the STATISTICA program, regression equations, to calculate the numerical values of the loading and unloading time of the soil, as well as the maximum reaction force of the soil and the corresponding values of the reliability coefficients of the multiple approximation, were obtained.Discussion and conclusion. The rheological model reproduces the asymmetric nature of changes in contact stresses during soil compaction by a vibrating roller, observed in experimental stress oscillograms obtained during field experimental studies. The results obtained are important for calculating the depth of stress propagation in the ground and the distribution of stresses in the ground after the passage of a vibrating roller using a wave approach to describing stress propagation in the ground. In the future, it is advisable to conduct a computational experiment with an expanded list of independent parameters of the roller, including the oscillation frequency.

Insights into the DFT‐computed electronic and optical properties of binary and doped: Selenide for optoelectronic applications

AbstractThis study investigates the alterations in structural, electronic, and optical characteristics of ZnSe1−x Inx (x = 0%, 12.5%, 25%) employing the framework of density functional theory (DFT), utilizing generalized gradient approximation (GGA) in conjunction with the full‐potential linearized augmented plane wave (FP‐LAPW) approach. The findings reveal that pure ZnSe exhibits a direct bandgap of 1.79 eV at the Γ point, which reduces to 0 eV upon doping with Indium, indicating a transition to metallic characteristics. This change is attributed to the predominant involvement of the d‐orbital of Zn, s‐orbital of Se, and p‐orbitals of Indium in the valence band of ZnSe1−x Inx materials. Conversely, the s‐orbital of Zn predominantly contributes to the conduction band of undoped ZnSe, whereas the d‐orbitals of Indium play a significant role in the conduction band of ZnSe1−x Inx (x = 0%, 12.5%, 25%). Moreover, the study computes other optical parameters, including reflectivity, electron energy loss spectrum, extinction coefficient, refractive index, and absorption coefficient, as functions of photon energy. A notable observation is the considerable rise in the zero‐frequency dielectric constant, ε1(0), which increases from 5.0 in pure ZnSe to 40.0 and 50.0 in Indium‐doped ZnSe, highlighting a significant alteration in electronic properties. Furthermore, optical analyses demonstrate an expansion in the absorption coefficient spectrum, which extends from photon energies of 2.0 eV in pristine ZnSe to begin at 0 eV in Indium‐doped variants, indicating a broadening of the material's capacity to absorb light across a wider spectrum of photon energies. This expansion infers improved light absorption potential, which could be particularly beneficial for the fabrication of light‐emitting modules and solar energy converters. These insights underline the considerable influence that Indium incorporation exerts on the band architecture and optical responses of ZnSe, offering critical directions for the advancement of optoelectronic devices.

Computational investigation of the structural, elastic, electronic, and thermodynamic properties of chloroperovskites GaXCl3 (X = Be, Ca, or Sr) using DFT framework

In this study, we employed the pseudopotential plane wave approach to examine the influence of the X atom (X = Be, Ca, or Sr) on the physical properties of isostructural chloroperovskites GaXCl3. The GGA-PBEsol functional was employed to simulate the exchange–correlation interactions. The computed equilibrium lattice parameters exhibit a high level of concordance with the existing theoretical findings. The cohesion energy and enthalpy of formation were computed to verify the energetic stability of the materials under consideration. The determined values of the single-crystal elastic constants (Cij) indicate that GaBeCl3 remains mechanically stable up to a hydrostatic pressure of 18 GPa. Similarly, GaCaCl3 preserves its stability up to 5 GPa, while GaSrCl3 remains mechanically stable up to 1.25 GPa. The projected Cij values were used to estimate several elastic moduli and related properties, including the shear and bulk moduli, sound wave speeds, Young’s modulus, Poisson’s ratio, and Debye temperature. The energy band structures of the studied compounds, as predicted by the HSE06 functional, demonstrate their wide bandgap semiconductor nature. Specifically, GaBeCl3 demonstrates an indirect bandgap of 3.828 eV, while GaCaCl3 reveals an indirect bandgap of 4.612 eV and GaSrCl3 has an indirect bandgap of 4.405 eV. The quasiharmonic Debye approach was employed to examine various thermal parameters, including the temperature dependence of the unit cell volume, bulk modulus, expansion coefficient, Debye temperature, isochoric and isobar heat capacities, Grüneisen parameter, and entropy function. It has been shown that GaBeCl3 demonstrates a lower thermal expansion coefficient and a higher Debye temperature in comparison to GaCaCl3 and GaSrCl3.

A Density Functional Theory Exploration of Cs2B′B″I6 (B′B″: BeCa, BeSr, GeCd, GeBe, GeMg) Halide Double Perovskites for Optimal Solar Cell and Renewable Energy Applications

A comprehensive investigation into the structural, elastic, optoelectronic, and thermoelectric properties of Cs2B′B″I6 halide double perovskites (DPs), where B′B″ represents various combinations, including BeCa, BeSr, GeCd, GeBe, and GeMg, is conducted. Using the full‐potential linearized augmented plane wave approach within the density functional theory framework, this analysis confirms the materials’ structural and dynamic stabilities through negative formation energies and adherence to elastic constant stability criteria. The generalized gradient approximation and the modified Becke–Johnson (mBJ) potential for electronic structure calculations are utilized. Notably, Cs2B′B″I6 DPs with B′B″ as BeCa or BeSr exhibit direct bandgaps (Γ–Γ), while those with B′B″ as GeCd, GeBe, or GeMg display indirect bandgaps (X–L). These findings offer valuable insights into the potential use of these materials in photovoltaic and optoelectronic devices. Furthermore, the exploration of thermoelectric properties, covering electrical conductivity, Seebeck coefficient, electronic thermal conductivity, and figure of merit at temperatures of 300, 600, and 900 K, suggests that Cs2B′B″I6 DPs, regardless of the specific B′B″ composition (BeCa, BeSr, GeCd, GeBe, GeMg), holds promise for applications in thermoelectric devices.

An analytical investigation into solute transport and sorption via intra-particle diffusion in the dual-porosity limit

We develop a mathematical model for adsorption based on averaging the flow around, and diffusion inside, adsorbent particles in a column. The model involves three coupled partial differential equations for the contaminant concentration both in the carrier fluid and within the particle as well as the adsorption rate. The adsorption rate is modelled using the Sips equation, which is suitable for describing both physical and chemical adsorption mechanisms. Non-dimensionalisation is used to determine the controlling parameter groups as well as to determine negligible terms and so reduce the system complexity. The inclusion of intra-particle diffusion introduces new dimensionless parameters to those found in standard works, including a form of internal Damköhler number and a new characteristic time scale. We provide a numerical method for the full model and show how in certain situations a travelling wave approach can be utilized to find analytical solutions. The model is validated against published experimental data for the removal of Mercury(II) and CO2. The results show excellent agreement with measurements of column outlet contaminant concentration and provide insights into the underlying chemical reactions.

Signal Processing Techniques of Lamb Waves for Structural Health Monitoring System - A Review

The structural health monitoring (SHM) system using Lamb wave approach has drawn a lot of interest because of its outstanding performance in terms of accuracy and adaptability. The implemented signal processing techniques in the diagnostic analysis are specifically reviewed in this work. The primary factors of the wide range of applied signal processing techniques are due to the multimode and dispersive behaviour of the Lamb waves. Several Lamb modes occur simultaneously, and because they have different dispersive characteristics, they can produce complicated superimposed signals. To effectively diagnose the observed signals, several mode separations approaches have been proposed. Generally, time-frequency representation is applied for signal processing techniques. The findings demonstrated that the proposed procedures were successful in decomposing the superimposed mode into individual modes for further analysis. All these works have shown how SHM systems based on Lamb waves have evolved over time to control and monitor the condition of the structure.

The Efficiency of Surface Impedance Technique in the Transverse Wave Approach for the EM-Modeling of Fractal-Like Tree Structure used in 5G Applications

Fractal antenna technology is a promising approach for 5G applications because its complex nature offers optimization potential in terms of time and space trade-offs. However, the computational effort required to analyze such antennas is significant. This paper investigates the Advanced Transverse Wave Approach (ATWA), which utilizes the surface impedance technique to improve simulation efficiency. This study introduces and analyzes a fractal-like 5G tree structure, displaying improved computational accuracy and efficacy, as well as peak memory utilization compared to current works. The proposed approach demonstrates significant effectiveness in enhancing the performance of complex fractal antennas for 5G technology and shows promise for integration with cloud, fog, and edge computing environments. This integration could potentially optimize data processing and network efficiency in these advanced computing landscapes.

Formation and propagation characteristics of pseudo-wavefronts of optical polarization states signal inside OPGW under lightning strikes

Lightning strikes on Optical Fiber Composite Overhead Ground Wires (OPGW) result in a phenomenon where the current traveling wave along the OPGW’s outer stranding propagates faster than the optical signals inside the fiber. This leads to the emergence of pseudo-wavefronts ahead of the optical polarization state signal after lightning strikes OPGW, introducing errors in lightning point localization based on the optical polarization state. This paper investigates the formation and propagation characteristics of pseudo-wavefronts. The study employs theoretical analysis and simulation to examine the process of optical polarization state formation during OPGW lightning strikes. Additionally, it conducts comparative analyses between laboratory-simulated OPGW lightning strikes and field measurements obtained from OPGW lightning monitoring systems. The results affirm the existence of the proposed pseudo-wavefront phenomenon, which substantially impacts the precision of lightning point localization. Notably, the duration of pseudo-wavefront effects increases with greater distance from the lightning point and higher lightning current amplitudes. These findings raise questions regarding the suitability of traditional wavefront calibration methods based on the traveling wave approach. This research contributes valuable insights for the practical implementation of lightning point localization methodologies relying on OPGW self-sensing technology.

Healthcare professionals' views on psychological support for children and families affected by skin conditions in the UK: A qualitative study

AbstractBackgroundSkin conditions can have a psychological impact on a child and their caregivers, however, support is not equally distributed between geographical regions in the United Kingdom (UK).ObjectivesThis study aimed to investigate the experience of National Health Service (NHS) healthcare professionals (HCPs) of addressing the psychological needs of children with skin conditions and their families, and gain expert opinion as to how services need to further develop.DesignHCPs were recruited to a qualitative study with an advert posted on social media.MethodsFifteen HCPs took part in interviews, including dermatologists (n = 4), dermatology nurse consultants/specialists (n = 4), clinical psychologists (n = 4), liaison psychiatrists (n = 2), and a children's psychological well‐being practitioner (n = 1).ResultsThematic analysis revealed children often presented with anxiety, depression, self‐harm and suicidal ideation. The impact on caregivers was equally profound. There were differences in service provision across the UK and all HCPs recognised the urgent need for psychological support to be integrated into standard care. Participants described how a range of interventions are typically required including cognitive behavioural therapy (CBT), and systemic approaches, as well as mindfulness/third‐wave approaches. Barriers to the delivery of psychological services were associated with a lack of funding and training opportunities for core and specialist staff alike. However, in some instances, participants had overcome these challenges to be able to deliver unique services.ConclusionsThere exist several barriers to providing paediatric psychological interventions, and many locations across the UK remain vulnerable as a result of continuing lack of national guidelines for the provision of psychological services.