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Suppression of phase separation in AlGaInAs compositionally graded buffers for 1550 nm photovoltaic converters on GaAs

We investigate strategies to suppress phase separation and reduce threading dislocation density (TDD) in AlGaInAs compositionally graded buffers (CGBs) that span the lattice constant range from GaAs to InP. Combining the results from high resolution x-ray diffraction, cathodoluminescence, transmission electron microscopy, and photovoltaic device measurements, we correlate the choices of epitaxial growth conditions with the defect structure of the CGBs and subsequent device performance. Both the use of substrates with high misorientation off (100) toward the (111)A plane and Zn doping instead of Si doping are shown to suppress phase separation and reduce TDD. We demonstrate a 0.74 eV GaInAs device grown on a GaAs substrate offcut 19.5° toward (111)A using a Zn-doped AlGaInAs CGB with TDD = 3.5 ± 0.2 × 106 cm−2 that has a bandgap-open circuit voltage offset of only 0.434 V measured under the AM1.5G solar spectrum. We characterized this device under high-intensity irradiance from a 1570 nm laser and measured a 31.9% peak laser power conversion efficiency at 3.6 W/cm2 irradiance. These results provide a roadmap to the manufacture of laser- and thermal-power conversion devices with the performance and cost-effectiveness needed to drive adoption of these technologies at scale.

Experimental study of different oxides in B2O3–ZnO–BaO glass system for gamma-ray shielding

Abstract Glass system of 45B2O3–20ZnO–30BaO–5X, (where X represents CaO, MgO, Al2O3, TiO2, CuO and Fe2O3) in mole percentage was investigated for gamma ray radiation shielding experimentally. Six glass composites were fabricated and the density was measured experimentally and the BZBCa glass sample has the least density with a value of 3.932 g cm−3 and this is due to the presence of CaO in it, and the sample BZBFe has the highest density with a value of 4.031 g cm−3. Through comparing the linear attenuation coefficient (LAC) data (experimental and Phy-X) for the BZBX glass samples, the LAC values for glass samples obtained experimentally and using Phy-X are in a very close range. All the glass samples have the greatest LAC values at 0.0595 MeV, the lowest energy value. Sample BZBCu has a LAC value of 16.203 1/cm, which is also the highest LAC value among all the studied glasses, this is as a result of the high density of this glass and due to the high atomic number of Cu. The glasses’ transmission factor (TF) at 1 cm thickness against energy was determined. The TF values of all the glasses were almost zero. The TF values increased significantly for all the glasses when the energy was increased to 0.662 MeV, and for sample BZBCa its TF value increases 74.08%, which was the highest TF value increase. The half-value layer and other shielding parameters have been determined experimentally.

Optimizing the thermoelectric properties of transition metal doped Sb2Te3 mediated by carrier effective mass

Charge carrier and phonon dynamics tuning are promising approaches for transport property modulation. Improvement of thermoelectric (TE) parameters via atomic substitution and band engineering is prevalent. Besides, carrier effective mass (m*) is a crucial factor that has a noteworthy influence on TE properties. Transition metals (TMs), possessing outstanding valence electronic properties and distinctive electronic state distributions, have recently been used as potential candidates for enhancing TE performance. Here, we report the structural, electronic, and TE characteristics of p-type Sb2Te3 by TM (=Fe, Co, Ni) doping. Consequently, the synergistic amelioration of electrical and thermal transport properties is elucidated. Structural and phonon vibrational properties are characterized by synchrotron powder x-ray diffraction and Raman spectroscopic (RS) measurements. Raman peak position and full-width at half-maximum provide insight into electron–phonon interactions and phonon anharmonicity. Anharmonic phonon–phonon interaction is illustrated via a four-phonon decay model. Furthermore, optothermal RS measurement is used to estimate the thermal conductivity κ of the samples. A reduction in the lattice thermal conductivity, κL, is observed after TM doping. Experimentally measured transport parameters, viz., S(T), ρ(T), and nH(T) are simulated via the Boltzmann transport equation (BTE), and reasonable quantitative agreement between the experimental and simulated data is obtained. The role of m* and valence band convergence, as estimated from BTE analysis, is highlighted. Weighted mobility and m* are found to be increased, significantly enhancing the power factor in the Co-doped sample. As compared to its pristine counterpart, around three times the improvement of the ZT value in Sb1.97Co0.03Te3 is reported.

Design of walking aids for the elderly based on the Kano-AHP-FEC method

Daily briefing: Huge study highlights new health risks of obesity drugs

Temperature and field dependences of the converse piezoelectric strain coefficient <i>d</i>*33 in PbFe1/2Nb1/2O3, 0.91PbFe1/2Nb1/2O3–0.09PbTiO3, and PbSc1/2Nb1/2O3 ceramics

Temperature and field dependences of the dielectric permittivity (ɛ) and unipolar electric field-induced strain (S) of PbFe1/2Nb1/2O3, PbSc1/2Nb1/2O3, and 0.91PbFe1/2Nb1/2O3–0.09PbTiO3 solid solution ceramics are studied in the temperature range from 25 to 160 °C. Using these experimental data, both the effective d*33eff = Smax/Emax and differential d*33dif = dS/dE converse piezoelectric moduli are calculated, and (E, T) diagrams were plotted. The possible critical behavior of the converse piezoelectric modulus d*33 and its correlation with the position of the known critical points in the (E, T) diagrams of studied ceramics are discussed.

Author Correction: Neuregulin 1 improves cognitive deficits and neuropathology in an Alzheimer’s disease model

Design of enhanced broadband optical couplers for long-infrared quantum well infrared photodetectors

Quantum-well infrared photodetectors (QWIPs) have emerged as a promising technology for broadband detection, particularly used in highly uniform large area focal plane array (FPA) imaging systems. However, one of the main challenges for broadband QWIPs is to design broadband optical couplers. In this paper, we propose a broadband optical scheme suited for the long-wavelength infrared quantum-well (QW) active layers. Our design features a multiple-stairstep reflection grating, which operates as a resonant waveguide in conjunction with the semiconductor layers. Surface plasmon polariton and transverse magnetic waveguide modes are effectively excited and regulated to match the active region. Over 40% absorption efficiency of the quantum wells is achieved across the entire range from 9 to 12 μm. Moreover, the structure demonstrates excellent fabrication tolerance and can be well compatible with FPAs, which is favored for practical applications.

The first multiple center prospective study of rhFSH CTP in patients undergoing assisted reproductive technology in China

Superconductivity of Sc(BN)3 under pressure

Advanced structural predictions, driven by first-principles calculations, facilitate the realization of a superconducting state under reduced pressure conditions while maintaining structural integrity. Scandium hexahydride (ScH6) exhibits structural stabilities under high pressure, adopting hexagonal and body-centered cubic structures that lead to high-temperature superconductivity. In this study, we theoretically provide a crucial reference for boron–nitrogen–substituted hydrogen above 100 GPa. Subsequently, Sc(BN)3 demonstrates significant structural stability, observed up to 200 GPa. Utilizing the stochastic self-consistent harmonic approximation sheds light on the influence of thermally excited lattice vibrations on the crystal structure of Sc(BN)3, emphasizing the impact of quantum ionic effects. These findings underscore the distinctive anharmonic behavior of Sc(BN)3, indicating its potential to facilitate boron–nitrogen–substituted hydrogen, which could find widespread applications in SC, achieving a critical temperature of 32.8 K under 150 GPa.

Construction of a prognostic prediction model for colorectal cancer based on 5-year clinical follow-up data

The Doppler effect explained with steam trains

Performance analysis of superconducting motors for electrical aircraft propulsion using electromagnetic–thermal coupling method

The aviation industry is focusing on the development of low-carbon emission technologies, with hydrogen-powered aviation hybrid technology being an important area of interest. Superconducting motors (SCMs) play a crucial role in these aviation hybrid systems due to their high power-to-weight (PTW) ratio. However, SCMs face challenges such as strong coupling of the electric field, magnetic field, and temperature field within the motor. Conventional electromagnetic–thermal coupling analysis methods are not suitable for SCMs, as they are slow to perform calculations that are also less accurate. This study proposes an electromagnetic-thermal coupling analysis model for SCMs, taking into account the constraints of critical current, critical magnetic field, and critical temperature of superconducting (SC) materials. The study analyzes the impact of the critical current of SC tapes, permanent magnet remanence, convection heat transfer coefficient between SC coils and cooling medium, AC loss reduction of SC coils, and motor speed on the ultimate power of SCMs. The results show that an optimal permanent magnet remanence can maximize the ultimate power, and the other parameters have been found to be positively correlated with the ultimate power of the SCM. To enhance the PTW ratio of SCMs, future research directions include increasing the critical current of SC materials, reducing the AC loss of SC coils, and improving the cooling effectiveness of SC coils.

Effect of H2O2 induced oxidative stress on volatile organic compounds in differentiated 3T3-L1 cells

Beyond black and white: an ecologist applies racial-justice principles to predators and their ecosystems

Ferro-ionic states and domains morphology in HfxZr1−xO2 nanoparticles

Unique polar properties of nanoscale hafnia-zirconia oxides (HfxZr1−xO2) are of great interest for condensed matter physics, nanophysics, and advanced applications. These properties are connected (at least partially) to the ionic–electronic and electrochemical phenomena at the surface, interfaces, and/or internal grain boundaries. Here, we calculated the phase diagrams, dielectric permittivity, spontaneous polar, and antipolar ordering, as well as the domain structure morphology in HfxZr1−xO2 nanoparticles covered by ionic–electronic charge originating from surface electrochemical adsorption. We revealed that the ferro-ionic coupling supports the polar long-range order in nanoscale HfxZr1−xO2, induces, and/or enlarges the stability region of the labyrinthine domains toward smaller sizes and smaller environmental dielectric constant at low concentrations of the surface ions. The ferro-ionic coupling causes the transition to the single-domain ferro-ionic state at high concentrations of the surface ions. We predict that the labyrinthine domain states, being multiple-degenerated, may significantly affect the emergence of the negative differential capacitance state in the nanograined/nanocrystalline HfxZr1−xO2 films.

Evaluation of land ecological security and driving factors in the Lower Yellow River Flood Plain based on quality, structure and function

A design technique for transforming statically designed phononic crystals and metamaterials into multifunctional, programmable active acoustic meta-devices

The active tuning of the bandgaps induced by the acoustic metamaterials has sparked significant interest among researchers. It opens up possibilities for programmable, multifunctional acoustic meta-devices. The static design of acoustic metamaterials, however, has limited automation capabilities, particularly for controlling sound propagation through the elastic solids. Designing acoustic metamaterials with fluid as the host medium, specifically air, significantly reduces these constraints. Given this observation, the present work demonstrates a novel design technique that transforms a Phononic Crystal (PnC) into an Active Acoustic Meta-device (AAMD). The designed AAMD has been demonstrated as programmable and multi-functional. It functions as an acoustic barrier over around 94% of the applied frequency sweep (a.f.s)., 300–3500 Hz. As an acoustic transmitter, it magnifies acoustic energy over around 50% of the a.f.s. Similarly, it functions as an acoustic switch over 100% of the a.f.s. This metadevice distinguishes itself by solely utilizing a two-phase material system and employing basic design elements, rather than common resonating elements, such as Helmholtz resonators or softer coatings.

Bioinformatics approach reveals the critical role of inflammation-related genes in age-related hearing loss

Adhesive nonlinearity analysis of longitudinal guided wave using circumference pasted piezoelectric array based nonlinear shear stress lag model

The adhesive layer between an ultrasonic transducer and a circular tube can generate a nonlinear signal during guided wave excitation and reception, which is called adhesive nonlinearity (AN). It may override the damage-related signals and result in false detection if not adequately evaluated and mitigated. This study investigated the AN of the guided wave excitation model composed of a piezoelectric array in a circular tube structure. The classical shear stress lag model was extended to the circumference pasted piezoelectric array-based nonlinear shear stress lag model to investigate the coupling properties of the AN and to evaluate the AN by comparing it with other nonlinear factors within a circular tube structure. On this basis, the nonlinear shear stress was combined with the normal mode expansion to establish a frequency tuning model for the AN, which allowed the effect of the AN to be minimized by adjusting the half-wavelength of the guided wave to match the length of the actuator. Finite-element analyses and experiments validated the tuning characteristics of the AN mentioned above. This work was used to mitigate the effect of the AN on the nonlinear guided wave during thermal damage evaluation.