Defects and impurities within semiconductor materials pose significant challenges. This investigation scrutinizes the response of a single dopant donor impurity located in nanostructured semiconductors, specifically quantum wells subjected to both harmonic and inharmonic confinement potentials. The primary focus of this inquiry centers on the analysis of binding energy, electron probability distribution, and diamagnetic susceptibility in connection with both the ground (1s) and excited (2p) electron states. Utilizing advanced computational techniques, specifically the Finite Elements Method (FEM) implemented through Python code, this study unveils a marked alteration in the interaction between electrons and impurities when exposed to external fields. Significantly, the characteristics of the confinement potential exert a substantial influence on the explored physical parameters. This research significantly advances our understanding of the interaction between impurities and intense fields, offering valuable insights into solid-state phenomena within low-dimensional systems. Consequently, it contributes to the design and fabrication of next-generation applications in the field of quantum well systems, encompassing areas such as lighting, detection, information processing, sensing, and energy conversion.

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Photonic crystal (PhC) has been studied for their potential to improve the efficiency of Cu₂ZnSnS₄ solar cells by increasing the generated photocurrent by integrating it as a back reflector with almost zero transmission through the absorption active zone of the solar cell. It was found that the thickness of PhC layers greatly affects the width of the photonic bandgap and that increasing the thickness of VO₂ causes it to shift to a higher wavelength range. The PhC layers were added at the back side of the solar cell in two different configurations: (Monoclinic (M) VO₂/TiO₂) and (Tetragonal (T) VO₂/TiO₂) via SCAPS model. The study found that the (M VO₂/TiO₂) configuration led to an enhancement of the device's efficiency from 11.02 to 12.79%, while the (T VO₂/TiO₂) reaches 16.88%. The study concluded that the PhC layers enhance the light-matter coupling and photonic coupling and improvement in the device's performance.

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Ultrathin MoO₃ semiconductor nanostructures have garnered significant interest as a promising nanomaterial for transparent nano- and optoelectronics, owing to their exceptional reactivity. Due to the shortage of knowledge about the electronic and optoelectronic properties of MoO₃/n-Si via an ALD system of few nanometers, we utilized the preparation of an ultrathin MoO₃ film at temperatures of 100, 150, 200, and 250 °C. The effect of the depositing temperatures on using bis(tbutylimido)bis(dimethylamino)molybdenum (VI) as a molybdenum source for highly stable UV photodetectors were reported. The ON–OFF and the photodetector dynamic behaviors of these samples under different applied voltages of 0, 0.5, 1, 2, 3, 4, and 5 V were collected. This study shows that the ultrasmooth and homogenous films of less than a 0.30 nm roughness deposited at 200 °C were used efficiently for high-performance UV photodetector behaviors with a high sheet carrier concentration of 7.6 × 10¹⁰ cm⁻² and external quantum efficiency of 1.72 × 10¹¹. The electronic parameters were analyzed based on thermionic emission theory, where Cheung and Nord’s methods were utilized to determine the photodetector electronic parameters, such as the ideality factor (n), barrier height (Φ₀), and series resistance (R_s). The n-factor values were higher in the low voltage region of the I–V diagram, potentially due to series resistance causing a voltage drop across the interfacial thin film and charge accumulation at the interface states between the MoO₃ and Si surfaces.

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Strontium and Yttrium-doped and co-doped BaTiO₃ (BT) ceramics with the stoichiometric formulas BaTiO₃, B_1-xSr_xTiO₃, Ba_1-xY_xTiO₃, BaTi_1-xY_xO₃, Ba_1-xY_xTi_1-xY_xO₃, and Ba_1-xSr_xTi_1-xY_xO₃ (x = 0.075) noted as BT, BSrT, BYT, BTY, BYTY, and BSrTY have been synthesized through sol-gel method. X-ray diffraction (XRD) patterns of the prepared ceramics, calcined at a slightly low temperature (950 °C/3h), displayed that BT, BSrT, and BYT ceramics possess tetragonal structures and BTY, BYTY, and BSrTY have a cubic structure. The incorporation of the Ba and/or Ti sites by Sr²⁺ and Y³⁺ ions in the lattice of BaTiO₃ ceramic and the behaviors of the crystalline characteristics in terms of the Y and Sr dopant were described in detail. The scanning electron microscopy (SEM) images demonstrated that the densification and grain size were strongly related to Sr and Y elements. UV–visible spectroscopy was used to study the optical behavior of the as-prepared ceramic samples and revealed that Sr and Y dopants reduce the optical band gap energy to 2.74 eV for the BSrTY compound. The outcomes also demonstrated that the levels of Urbach energy are indicative of the created disorder following the inclusion of Yttrium. The measurements of the thermal conductivity indicated the influence of the doping mechanism on the thermal conductivity results of the synthesized samples. Indeed, the thermal conductivity of BaTiO₃ is decreased with Sr and Y dopants and found to be in the range of 085–2.23 W.m^-1. K⁻¹ at room temperature and decreases slightly with increasing temperature from 2.02 to 0.73-W.m^-1. K⁻¹. Moreover, the microstructure and grains distribution of the BT, BSrT, BYT, BTY, BYTY, and BSrTY samples impacted the compressive strength, hence; the compressive strength was minimized as the grain size decreased.

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The use of electronic devices that incorporate multilayer ceramic capacitors (MLCCs) is on the rise, requiring materials with good electrical properties and a narrow band gap. This study synthesized yttrium-substituted barium titanate (Ba_1-xY_xTiO₃, BYT) using a sol-gel process at 950 °C with varying concentrations of yttrium (0 ≤ x ≤ 0.3). X-ray diffraction analysis showed that the tetragonal phase became less pronounced as the yttrium content increased. The samples had varying grain sizes and porosity, with the BY30%T sample having the narrowest band gap at 2.21 eV. The BYT ceramic with 30% yttrium had a thermal conductivity of up to 7 W/m K and an electrical conductivity down to 0.002 (Ω cm)⁻¹ at 180 °C. The current-voltage characteristics of the BYT MLCC were also studied, showing potential use in next-generation high-capacity MLCCs. This work presents BYT as a promising material for these types of capacitors.

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This study explored the efficient utilization of natural zeolite tuff and aluminum dross for making porous ceramic bricks, aiming to address environmental damage from waste disposal. Different compositions of these materials were used to create six batches of bricks, followed by heat treatment at varying temperatures (950–1150 °C). The raw materials and the sintered samples were analyzed using various characterization techniques. The results showed that bricks incorporating 30 % aluminum dross and sintered at 1150 °C had the lowest thermal conductivity of 0.3 W/m·K. On the other hand, bricks containing 20 % aluminum dross and sintered at the same temperature exhibited the highest compressive strength (58 MPa), a bulk density of 1.9 g/cm³, and a water absorption of approximately 13 %. All samples exceeded the minimum compressive strength requirements. This study demonstrates the feasibility of using natural zeolite tuff and aluminum dross to develop composite bricks, providing an effective waste disposal solution for sustainable development and reduced environmental pollution.

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The BTO, BFTC, and BCTF compounds were synthesized by the sol-gel method. The XRD study revealed the formation of single-phase tetragonal perovskite structures with the space group (P4mm). The crystalline parameters were studied as a function of Fe and Co contents and occupation of Ba and/or Ti sites by Fe and Co in the BTO lattice. It was found that the obtained strain increases when Ba²⁺ is substituted by Co²⁺ and Ti⁴⁺ by Fe³⁺. The Raman investigation confirmed the existence of three active modes (B1/E (TO1LO), (E (TO)/A1(TO3), and (A 1(LO)/E (TO), all of which are related to the existence of the tetragonal phase and strongly support the XRD results. The microstructural study showed a clear correlation between the presence of Fe and Co and the grain size distribution. Optical studies revealed the improvement in band gap energy with transition-metal (Fe and Co) co-doped BTO ceramics. The decrease in the band gap is explained by the competing effects of Columbian interactions, microdeformation, and oxygen defects. The results indicate that the presence of Fe and Co dopants enhances the absorption in the BTO ceramic. The dopants demonstrated an effect on thermal conductivity: they decreased the thermal conductivity of BTO, which is in the range of 0.76-2.23 W m^-1 K^-1 at room temperature and 2.02-0.27 W m^-1 K^-1 at elevated temperatures. The microstructure of the manufactured materials and the grain size distribution affect the compressive strength.

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Nanostructures of ultrathin 2D MoO₃ semiconductors have gained significant attention in the field of transparent optoelectronics and nanophotonics due to their exceptional responsiveness. In this study, we investigate self-powered α-MoO₃/Ir/α-MoO₃ photodetectors, focusing on the influence of induced hot electrons in ultrathin α-MoO₃ when combined with an ultrathin Ir plasmonic layer. Our results reveal the presence of both positive and negative photoconductivity at a 0 V bias voltage. Notably, by integrating a 2 nm Ir layer between post-annealed α-MoO₃ films, we achieve remarkable performance metrics, including a high I_ON/I_OFF ratio of 3.8 × 10⁶, external quantum efficiency of 132, and detectivity of 3.4 × 10¹¹ Jones at 0 V bias. Furthermore, the response time is impressively short, with only 0.2 ms, supported by an exceptionally low MoO₃ surface roughness of 0.1 nm. The observed negative photoresponse is attributed to O₂ desorption from the MoO₃ surface, resulting in increased carrier density and reduced mobility in the Ir layer due to Coulomb trapping and oxygen vacancy deep levels. Consequently, this leads to a decreased carrier mobility and diminished current in the heterostructure. Our findings underscore the enormous potential of ultrathin MoO₃ semiconductors for high-performance negative conductivity optoelectronics and photonic applications.

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The aim of this research is to analyze the influence of various factors on the photo-ionization cross-section in (Al, Ga)N/AlN double triangular quantum wells. Using the finite difference method, the effects of the electric field, hydrostatic pressure, temperature, and Ga concentration were investigated within the effective mass and parabolic approximations. Our findings show that the photo-ionization cross-section (PICS) is highly dependent on all the variables under consideration. The optical spectra were blue-shifted with increasing electric field and pressure and red-shifted with increasing temperature and impurity displacement far from the center of the structure. Furthermore, it was found that changes in gallium content and impurity position can increase the PICS amplitude. A comparison of the obtained results with the existing literature as a limiting case of the reported problem is also provided, and excellent agreement is found.

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The phenomenon of hot carriers, which are generated through the nonradiative decay of surface plasmons in ultrathin metallic films, offers an intriguing opportunity for subbandgap photodetection even at room temperature. These hot carriers possess sufficient energy to inject into the conduction band of a semiconductor material. The groundbreaking use of iridium (Ir) ultrathin film as an ultraviolet (UV) plasmonic material on silicon (Si) for high-performance photodetectors (PHDs) has been successfully demonstrated. Elevating the thickness of the sputtered Ir film to 4 nm yields a notable surge in photocurrent, registering an impressive 600 μA under 365 nm UV illumination with electron mobility of 1.37E3 cm² V⁻¹ s. This PHD exhibits excellent OFF-ON photoresponses at various applied voltages ranging from 0 to 5 V, maintaining a stable photocurrent. Under UV illumination, it displays exceptional performance, achieving a high detectivity of 1.25E14 Jones and a responsivity of 1.28 A W⁻¹. These outstanding results underscore the significant advantages of increasing the thickness of the Ir film in PHDs, leading to improvements in conductivity, detectivity, external quantum efficiency, responsivity, as well as superior sensitivity for light detection.

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Ultra-thin quantum wells, with their unique charge confinement effects, are essential in enhancing the electronic and optical properties crucial for optoelectronic device optimization. This study focuses on theoretical investigations into radiative recombination lifetimes in nanostructures, specifically addressing both intra-subband (ISB: e-e) and band-to-band (BTB: e-hh) transitions within InGaN/GaN quantum wells (QWs). Our research unveils that the radiative lifetimes in ISB and BTB transitions are significantly influenced by external excitation, particularly in thin-layered QWs with strong confinement effects. In the case of ISB transitions (e-e), the recombination lifetimes span a range from 0.1 to 4.7 ns, indicating relatively longer durations. On the other hand, BTB transitions (e-hh) exhibit quicker lifetimes, falling within the range of 0.01 to 1 ns, indicating comparatively faster recombination processes. However, it is crucial to note that the thickness of the quantum well layer exerts a substantial influence on the radiative lifetime, whereas the presence of impurities has a comparatively minor impact on these recombination lifetimes. This research advances our understanding of transition lifetimes in quantum well systems, promising enhancements across optoelectronic applications, including laser diodes and advanced technologies in detection, sensing, and telecommunications.@en

This computational investigation delves into the electronic and optical attributes of InGaN/GaN nanostructures subjected to both harmonic and anharmonic confinement potentials, coupled with the influence of a nonresonant intense laser field (ILF). The theoretical framework incorporates higher-order anharmonic terms, specifically quartic and sextic terms. The solutions to the Schrödinger equation have been computed employing the finite element method and the effective mass theory. Moreover, linear and third-order nonlinear optical absorption coefficients are derived via a density matrix expansion. Our analysis reveals the feasibility of manipulating electronic and optical properties by adjusting confinement potential parameters, system attributes, and laser field intensity. In addition, the ILF induces remarkable modifications, characterized by reduced resonance peak amplitudes and a blue shift in absorption coefficients. Intriguingly, regardless of potential harmonicity, the impact of incident electromagnetic intensity is notably more pronounced in the absence of the ILF. These findings hold significant promise for advancing theoretical predictions, providing valuable insights into the intricate interplay between confinement potentials, laser fields, and their effects on electronic and optical behaviors within nanostructures.

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Porous mullite-based ceramics have been developed using a mixture of zeolite-poor rock and alumina through mechanical activation and reactive sintering. The experimental findings demonstrate that the in-situ mullite growth may develop in a variety of shapes, including whiskers, nanofiber, nanonetwork and diamond-like particles. The XRD examination indicates that the samples sintered at 1500 °C are mostly made of the mullite phase. The SEM photographs show that as the sintering temperature increases, the mullitization process takes place first in zeolite-poor rock particles, and subsequently, alumina combines with the silica-containing phase via a liquid-phase sintering mechanism to produce an interlocking network of extended secondary mullite. The effects of mullite formation and the sintering temperature on various properties of the sintered samples, such as their density, apparent porosity, thermal conductivity, strength, wear resistance, composition, morphologies, and microstructural characteristics of the sintered samples were studied. Increasing the sintering temperature from 1100 to 1500 °C improved the different properties. The density increased from 1.9 to 2.1 g/cm³, thermal conductivity rose from 0.9 to 1.6 W/m.K, compressive strength escalated from 18.9 to 92.1 MPa, and worn material volume decreased from 2444 to 36.9 mm³ after a 5-min abrasion test.

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The present research examines the development of new porous ceramic bricks from Hungarian zeolitic tuff and tea waste as building materials. Recycling waste materials as a pore-forming agent in brick-making is a promising solution to environmental and economic challenges. Several zeolitic tuff/tea waste admixtures were milled in the planetary ball milling to produce homogenous powders. The substitution ratios were maintained as 0 %, 2 %, 4 %, 6 %, 8 %, 10 %, and 12 % by wt of zeolitic tuff. The ceramic disks were produced from the prepared mixtures via dry pressing and sintering at various temperatures (950–1250 °C) for consolidation. The produced bricks were investigated based on bulk density, apparent porosity, water absorption, volume shrinkage, thermal conductivity and compressive strength, as well as mineralogical, chemical, and morphological studies. The mineralogical determination confirms the existence of clinoptilolite, montmorillonite, cristobalite and illite as major phases in zeolite tuff. The experimental results reveal that the addition of tea waste produces hybrid bricks with better thermal insulation (0.17–0.504 W/m K), lighter weight (1.37–1.81 g/cm³), and lower compressive strength (5.52–34.4 MPa). However, the compressive strength value still lies within the range required by the standards. The production of burned bricks containing up to 10 wt% tea waste is viable without causing major changes in their technical characteristics. Developing new porous bricks using waste materials can help expand the application of sustainable and cost-effective insulation bricks in the construction industry.

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Self-powered UV sensing has enormous potential in military and civilian applications. However, achieving high responsivity and fast response/recovery time presents significant challenges. Self-powered photodetectors (PDs) have several advantages over traditional PDs, including higher sensitivity, lower power consumption, and simpler design. This study introduces a breakthrough self-powered PD that uses a Schottky junction of 2D α-MoO₃/iridium (Ir)/Si ultrathin film to detect 365 nm light at 0 V bias through using atomic layer deposition (ALD) and sputtering systems. The PD response is enhanced by plasmonic Ir-induced hot carriers, enabling detection in a mere 0.1 ms. Incorporating a 4 nm Ir layer boosts the responsivity from 0 to 34 A W⁻¹, and the external quantum efficiency is elevated from 0 to 7E11 under 365 nm light illumination. It also has a high I_ON/I_OFF ratio of 11.22E4 at 0 V. These results make the MoO₃/4 nm Ir/Si structure an interesting option for self-powered PDs with high efficiency, and the use of a simple ALD system for large-scale fabrication of 2D α-MoO₃ on hot carrier Ir plasmonic layer. The findings of this research hold tremendous promise in the field of UV sensing and can lead to exciting developments in military and civilian technology.

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This study focused on investigating the optoelectronic properties of molybdenum trioxide (α-MoO₃) thin films using the atomic layer deposition (ALD) technique through different cycle numbers and theoretical investigation. Initial band gap calculations using standard DFT with GGA-PBE resulted in a value of 1.19 eV, which deviated significantly from experimental measurements. The GGA + U method with Hubbard U corrections was applied for the first time to improve the accuracy. This refinement led to a more precise band gap value of 3.09 eV, closely matching previously reported experimental data. The electronic parameters of the α-MoO₃ photodetector, such as ideality factor (n), barrier height (Φ₀), and series resistance (R_s), were analyzed using the thermionic emission theory and confirmed by Cheung and Nord's methods. The results demonstrated that the sample deposited with 100 pulses exhibited higher photodetector performance under UV illumination, despite having a lower R_s.

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The application of the photonic superlattice in advanced photonics has become a demanding field, especially for two-dimensional and strongly correlated oxides. Because it experiences an abrupt metal-insulator transition near ambient temperature, where the electrical resistivity varies by orders of magnitude, vanadium oxide (VO2) shows potential as a building block for infrared switching and sensing devices. We reported a first principle study of superlattice structures of VO2 as a strongly correlated phase transition material and tungsten diselenide (WSe2) as a two-dimensional transition metal dichalcogenide layer. Based on first-principles calculations, we exploit the effect of semiconductor monoclinic and metallic tetragonal state of VO2 with WSe2 in a photonic superlattices structure through the near and mid-infrared (NIR-MIR) thermochromic phase transition regions. By increasing the thickness of the VO2 layer, the photonic bandgap (PhB) gets red-shifted. We observed linear dependence of the PhB width on the VO2 thickness. For the monoclinic case of VO2, the number of the forbidden bands increase with the number of layers of WSe2. New forbidden gaps are preferred to appear at a slight angle of incidence, and the wider one can predominate at larger angles. We presented an efficient way to control the flow of the NIR-MIR in both summer and winter environments for phase transition and photonic thermochromic applications. This study's findings may help understand vanadium oxide's role in tunable photonic superlattice for infrared switchable devices and optical filters.

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This study was on the optoelectronic properties of multilayered two-dimensional MoS₂ and WS₂ materials on a silicon substrate using sputtering physical vapor deposition (PVD) and chemical vapor deposition (CVD) techniques. For the first time, we report ultraviolet (UV) photoresponses under air, CO₂, and O₂ environments at different flow rates. The electrical Hall effect measurement showed the existence of MoS₂ (n-type)/Si (p-type) and WS₂ (P-type)/Si (p-type) heterojunctions with a higher sheet carrier concentration of 5.50 × 10⁵ cm⁻² for WS₂ thin film. The IV electrical results revealed that WS₂ is more reactive than MoS₂ film under different gas stimuli. WS₂ film showed high stability under different bias voltages, even at zero bias voltage, due to the noticeably good carrier mobility of 29.8 × 10² cm²/V. WS₂ film indicated a fast rise/decay time of 0.23/0.21 s under air while a faster response of 0.190/0.10 s under a CO₂ environment was observed. Additionally, the external quantum efficiency of WS₂ revealed a remarkable enhancement in the CO₂ environment of 1.62 × 10⁸ compared to MoS₂ film with 6.74 × 10⁶. According to our findings, the presence of CO₂ on the surface of WS₂ improves such optoelectronic properties as photocurrent gain, photoresponsivity, external quantum efficiency, and detectivity. These results indicate potential applications of WS₂ as a photodetector under gas stimuli for future optoelectronic applications.

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Artificial periodic structures drew a lot of attention because of their ability to be built with novel acoustic features. A novel nanostructured phononic superlattice (NPhS) based two-dimensional multilayer structure as a high-sensitive multichannel liquid sensor that provided bright multichannel band gap windows has been introduced. Theoretically, the designed structure is composed of [(MoS₂/PtSe₂)⁴] NPhS with a cavity filled with different concentrations of Ethylene Glycol at room temperature toward acoustic bandgap engineering multichannel sensor. We examined the interaction of acoustic waves with nano and bulk phononic superlattice (PhS) structures. In addition, we studied the effect of using different analyte layer thicknesses on the resonance peaks that appeared inside the band gaps. Many sharp resonance peaks appeared in multi-band gaps, which introduced high sensitivity, Q-factor, and figure of merit (FOM) values for each concentration of Ethylene Glycol. Furthermore, the effect of resonance peaks' full width at half maximum (FWHM) on the Q-factor of the NPhS multichannel sensor has been studied. From our results, the relation between the sensitivity of our multichannel sensor and the resonance frequency of each concentration shows a linear behavior. The highest sensitivity was obtained for a 1.00 m% concentration of 0.21 (GHz/(kg/m³)) at a resonance frequency value of 0.21 THz. In addition, the NPhS multichannel sensor recorded the highest Q-factor for 0.8069 m% with a value of 1744 and the highest FOM for 0.3819 m% with a value of 0.05988 (m³/kg). Moreover, we studied the effect of temperature on the sensitivity of the NPhS multichannel sensor. We showed the highest sensitivity value of 1.79 (GHz/^o C) at 10 °C towards Ethylene Glycol. Further, the dispersion relation of an acoustic wave propagating inside perfect and defected nano and bulk PhS structures has been introduced. Our proposed multichannel liquid sensor can introduce a novel sensitivity at Terahertz frequency ranges.

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To study the structural, electronic, and optical properties of lead-free Barium titanate BaTiO₃ (BT) ferroelectric material in its tetragonal structure, a combination of experimental and theoretical studies has been used and the obtained results were discussed. The studied BT compound was prepared via the sol–gel technique. The calculated bandgap energy (E_g) and structural parameters of BT are determined using four types of exchange–correlation functionals (PBE, PBEsol, LDA, and PW91) in the perspective of the density functional theory (DFT). XRD and Raman analysis have shown that BT ceramic exhibits a tetragonal phase structure without any trace of impurity phases. The UV–vis investigation showed that BT has a bandgap energy of 3.19 eV, which is larger than the theoretically calculated values. The computed lattice parameter c is overestimated (as large as ~1% deviation) when using the LDA approximation. In contrast, PBEsol proved that those lattice constants were close to the experimental values (a deviation of less than 1%).

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