The isothermal uniaxial hot compression experiments were carried out on the Mg-4Sm-3Gd-0.9Al alloy after solution treatment. The strain-compensated constitutive equation and hot processing maps were established. The effects of Al2RE phase on the formation of recrystallized grains were studied. The results showed that the average grain size of the alloy was 27.89 μm and the microstructure was mainly composed of α-Mg matrix and uniformly distributed second phase (Al2RE, RE = Sm and Gd) before hot deformation. After hot compression, true stress-strain curves showed significant dynamic recrystallization characteristics and Al2RE phase reduced the peak stress of the alloy. The stress-strain curves predicted by the strain-compensated constitutive equation showed good agreement with the experimental results. The optimal processing parameters of the alloy were obtained as T = 440 °C and ɛ̇ = 0.01 s−1. The Particle Stimulated Nucleation (PSN) mechanism triggered by the Al2RE phase significantly promotes the formation of dynamic recrystallization. This not only reduces workability temperature but also inhibits grain growth, thereby effectively enhancing plastic deformation capacity.

The microstructure and mechanical properties of as-cast Mg-4Sm-3Gd-0.9Al alloy were systematically investigated. Notably, the alloy exhibits a fine grain size of 19 mu m and excellent mechanical properties: UTS = 243 MPa, YS = 174 MPa, and EL = 9.8%. The dominant second phases are blocky Al2RE and short rod-like Al11RE3. The Al2RE phases act as heterogeneous nucleation sites to promote nucleation and effectively refine grains. The enhanced mechanical properties are primarily attributed to grain refinement strengthening and second-phase strengthening.

We present a systematic first-principles study on the electronic and mechanical properties of both monolayer and bulk X2Si2Y6 (X = As, Sb, Bi; Y = Se, Te) compounds. Our calculations reveal that all the materials are mechanically, dynamically and thermally stable. The monolayers are indirect-gap semiconductors with band gaps ranging from 1.21 eV to 1.66 eV, while the bulks exhibit direct gaps ranging from 0.41 eV to 1.03 eV. Charge density and charge density difference analyses uncover the strong covalent Si–Si bonds, mixed covalent-ionic Si–Y bonds, and primarily ionic X–Y bonds. The X2Si2Y6 monolayers possess low elastic constants (C11 = 35 N/m–60 N/m), indicating high deformability. The bulk materials exhibit pronounced mechanical anisotropy with Young’s modulus varying by up to an order of magnitude depending on crystallographic direction. Notably, several compositions display auxetic behavior with negative Poisson’s ratios. The average polycrystalline moduli obtained from the Voigt–Reuss–Hill scheme reveal systematic trends with chemical substitution, where tellurides exhibit higher shear stiffness but lower bulk moduli compared to selenides.

The as-cast Mg-4Sm-3Gd-0.5Zr alloy was subjected to hot compression testing using a Gleeble-1500 simulator. The tests were conducted at temperatures ranging from 360 to 480 degrees C, with strain rates between 0.01 and 1 s-1 . The true stress-strain curves were analyzed, thermal activation energy was calculated, constitutive equations were derived, and hot processing maps were created. The deformed microstructure and second-phase particles were characterized using electron backscatter diffraction (EBSD), X-ray diffraction (XRD), and energy-dispersive spectroscopy (EDS). The results show that dynamic recrystallization (DRX) occurred clearly during compression. The primary DRX mechanisms observed were discontinuous DRX (DDRX), continuous DRX (CDRX), and particlestimulated nucleation (PSN). The activation energy for hot deformation was determined to be 235.67 kJ & sdot;mol-1 . Based on the hot processing maps, two optimal processing windows were identified: 380-450 degrees C with strain rates of 0.01-0.03 s-1 and 460-480 degrees C with strain rates of 0.01-1 s-1 . Coupled cellular automaton and finite element (CA-FE) simulations showed good agreement with experimental results, accurately predicting DRX behavior and microstructural changes under various conditions. This study successfully established a comprehensive multiscale simulation framework coupling CA-FE. This model not only predicted the evolution of dynamic recrystallization behavior but also revealed the coupled influence mechanisms of temperature and strain rate on the microstructure. By integrating the established constitutive and grain size models, the optimal hot processing window for this alloy was ultimately determined. This provides crucial theoretical support and an efficient predictive tool for the hot deformation process design and microstructure control of high-samarium-containing magnesium alloys.

Based on first-principles calculations, the dynamical stability, electronic structures and magnetic properties of two-dimensional (2D) M2X3 (M=V, Cr, Mn, Fe, Co, Ni; X = O, S, Se, Te) compounds are investigated. According to the results, we identify a series of dynamically, mechanically and thermally stable materials with different magnetic configurations. V2O3, V2S3, V2Se3, V2Te3, Cr2Se3, Cr2Te3, Fe2O3, Fe2S3 and Fe2Se3 are antiferromagnetic (AFM) insulators, with energy gaps ranging from 0.09 eV to 1.67 eV. Cr2S3 is a ferromagnetic (FM) insulator with an indirect energy gap of 0.90 eV. Mn2S3, Mn2Se3, Mn2Te3 and Co2Se3 are FM metals. Particularly, we predict several rare AFM metals, including Fe2Te3, Co2Te3 and Ni2Se3. The exchange coupling parameters are obtained by fitting the Ising model to first-principles energies to help understand the magnetic mechanism. Monte Carlo simulations indicate that the magnetic phase-transition temperatures of these materials span a wide range, from approximately 150 K to 1000 K. The electronic structures and the magnetic ground states of these 2D compounds can be effectively tuned by biaxial strain and charge doping. This work enriches the family of 2D magnetic materials, especially the family of rare FM insulators and AFM metals.

Photocatalytic water splitting has emerged as a viable strategy to address the prevailing environmental and energy dilemmas globally. Nonetheless, a significant obstacle to this sustainable technology lies in the inadequate separation and effective utilization of photogenerated electron-hole pairs within photocatalytic materials. Here, we constructed a novel double S-scheme MIL-125(Ti)/ZnIn2S4/ZnS quantum dots (MOF/ZIS/ZnS) heterojunction photocatalyst by facile hydrothermal and solvothermal method for photocatalytic hydrogen evolution (PHE). The optimal MOF/ZIS/ZnS photocatalyst demonstrates a remarkable hydrogen generation rate of 0.943 mmol center dot h-1 center dot g-1, and it is 10.84 times higher than pure ZIS (0.087 mmol center dot h-1 center dot g-1). This significant boost in hydrogen production efficiency is due to the creation of a dual S-scheme heterojunction and an intrinsic electric field (IEF) among MOF, ZIS, and ZnS, which promotes charge transfer, reduces photogenerated carrier recombination, prolongs the lifespan of light-induced carriers and boosts the redox potential of photoexcited charges. This study provides fresh perspectives on the optimal design of dual S-scheme photocatalysts by harnessing energy band manipulation and IEF adjustments.

In ultra-precision displacement measurement, employing multiple probes of a laser interferometric displacement sensor (LIDS) for differential measurement can significantly suppress the common-mode noises to improve the measurement quality. The efficacy of differential measurement is contingent upon the agreement among the LIDS probes. Therefore, it is crucial to scientifically evaluate this agreement. At the nanometer scale, it is challenging for multiple probes to simultaneously measure the same target and evaluate their agreement. Based on the Bland-Altman method (B-A method), we have extended the B-A method and developed a method that utilizing a single displacement reference measures and evaluates the agreement among the 4 LIDS probes. The proposed method facilitates nanometer-level quantification of multi-probe agreement. Besides, the inconsistency errors in agreement evaluation among the 4 probes were within +/- 1 nm and the differential measurements with paired probes verified the results. Furthermore, the proposed method can be extended to evaluate the agreement of any number of LIDS probes.

Fractional exhaled nitric oxide (FeNO) has been identified as a biomarker for asthma that can aid in both its diagnosis and severity monitoring. Here, a high-performance NO gas sensor based on rGO-decorated biomass carbon was fabricated. Operating at room temperature, the sensor can detect 50 ppb NO in exhaled breaths, which is a critical concentration threshold in asthma diagnosis and management. Clinically, 11 exhaled breath samples from asthma patients and 13 from healthy controls were collected. The sensor successfully discriminated between asthma patients and healthy controls directly via the response values. The severity of asthma in three inpatients was monitored using the sensor in parallel with the clinical standard tool, the peak flow meter. A high degree of consistency was observed between the severity monitoring results obtained by the two methods. Specifically, a strong positive correlation between the sensor’s response values and the clinical standard diurnal PEF variation was found, with a Pearson correlation coefficient of r = 0.84 (p<0.05), further validating the sensor’s reliability for monitoring asthma severity. This sensor holds significant potential for clinical application in asthma diagnosis and could replace current, complex, and limited PEF testing methods for asthma severity monitoring.

Exploiting a portable and highly efficient low frequency (LF: 3-300 kHz) underwater communication system for underwater electric (E) field communication is still challenging since it operates at the non-resonance frequency. A novel LF communication system using one pair metal-quartz antennas has been presented. These antennas work at their electromechanical resonance of 32.765kHz in LF band. The metal-quartz antennas have high Q of 42048.4 and shows a decrease with 1/r in seawater (r is communication distance). With 1mW driving power, the radiation electric field for the metal-quartz transmitter is 0.93V/m. The metal-quartz transmitter has limit of detection (LOD) of 24.6nV and sensitivity of 11.3V/V center dot m(-1). A message communication of "SJTU" was demonstrated on the metal-quartz transmitter and receiver. This proposed antenna provides a new approach to the construction of future underwater Internet of Things (IOT) communication.

Ultra-low frequency (ULF: 0.3-3 kHz) underwater receiving antenna (URA) is a prerequisite for an underwater communication system to achieve stable communication. However, the realization of the URA with high sensitivity and wide bandwidth at ULF electric field is still a challenge due to the limitation of the gain-bandwidth product in resonance condition. To address the issue, we propose an URA that consists of an up-conversion system based on a nonlinear switch and a receiver based on a quartz bimorph. The proposed URA at 635Hz electric field has a minimum detection limit of 4 mu V/m and a sensitivity of 0.692V/V center dot m(-1), which is 1.89 times higher than that of the URA based on quartz. Moreover, the bandwidth of the URA was broad 154% by two quartzes in parallel compared to that with quartz. This proposed URA provides a new approach to the construction of future underwater monitoring networks.

Fractional exhaled nitric oxide (FeNO) is widely recognized as a reliable biomarker for asthma. FeNO sensors can help diagnose asthma and monitor its severity. In this study, an ultrasensitive chemiresistive gas sensor, sensitive to the key breath biomarkers of asthma─nitric oxide (NO) and H2S─was fabricated using Ag-decorated ZnO. The sensor exhibits detection limits of 5 ppb for NO and 50 ppb for H2S, and it can discriminate 10 ppb NO and 60 ppb H2S from the exhaled breaths. Clinically, a total of 80 exhaled breath samples were collected and tested, including 40 from asthma patients (APs) and 40 from healthy control subjects (HCs). The AP group was effectively distinguished from the HC group using a pattern recognition algorithm (PCA), attributed to the sensor's beneficial cross-sensitivity to asthma biomarkers. A diagnostic model distinguishing asthma from non-asthma was constructed using the support vector machine (SVM) algorithm, achieving an overall accuracy, sensitivity, and specificity of 0.81, 0.88, and 0.75, respectively. The area under the curve (AUC) value for all subjects in the receiver operating characteristic (ROC) curve was 0.92. The severity of asthma in three inpatients was monitored using the clinical evaluation method of diurnal peak expiratory flow (PEF) variation, alongside our sensor. The sensor's response values exhibited a strong correlation (r = -0.74 (p < 0.05)) with the diurnal PEF variation values. To validate the sensor's diagnostic capability, six breath samples from both HCs and APs were tested simultaneously using our sensor and a commercial electrochemical NO sensor utilized clinically. With r = -0.98 (p < 0.05) and R2 = 0.94, a strong linear relationship between two types of response values was observed, confirming the sensor's accuracy and reliability in detecting NO concentrations in exhaled breath. Theoretical adsorption models of NO on the surface of the sensor were constructed using DFT calculations to elucidate the mechanisms driving the sensor's ultrasensitivity. Overall, the sensor demonstrates a significant potential for use in clinical practice to diagnose asthma and monitor its severity.

The development of efficient, stable, and user-friendly adsorbents for the removal of Cr(VI) from wastewater has become a hot issue for researchers. The present study focused on the synthesis of a composite material, namely zeolitic imidazolate framework (ZIF8)- cellulose loading GR(II)/Cu (MCH-ZIF8@GR(II)/Cu), aiming to leverage the advantages of each component for enhancing the rapid decontamination and removal efficiency of Cr(VI) from wastewater. The Cr(VI) removal efficiency of MCH-ZIF8@GR(II)/Cu composite reached nearly 100 % within the pH range of 3 to 4, remained above 90 % within the pH range of 5 to 6, and still maintained a significant removal rate of approximately 80 % even at a pH level of 7. Even in the presence of Ca2+, Mg2+, and CO32-, the removal efficiency remained approximately 90 %, exhibiting a high anti-interference ability. MCH-ZIF8@GR(II)/Cu composite exhibited outstanding cycling performance, with a Cr(VI) removal efficiency of 87.8 % even after undergoing five cycles. The main mechanism of Cr(VI) removal by MCH-ZIF8@GR(II)/Cu is primarily attributed to anion exchange, as supported by both experimental characterizations and DFT calculations. The present study demonstrates the superiority of anion exchange in the removal of Cr(VI) and offers a novel perspective for effectively treating wastewater contaminated with Cr(VI).

High-performance H 2 gas sensors based on monolayer 2D metal oxide a-MoO 3 doped with Pt/Rh has been predicted. With a binding energy of -5.262 eV/-5.877 eV, the substitutional doping of Pt/Rh for Mo is a stable doping. After adsorbing O 2 in air, the band gap of Pt/Rh-a-MoO 3 decreases by 0.62 eV/0.51 eV due to the appearance of the impurity levels and the band narrowing effect. Due to such large decrease, electrons in the valence band can be excited more easily into the conduction band to produce more O -2( ao , which would oxidize more H 2 to generate H 2 O or hydroxyl along with releasing more electrons to the sensor and increasing the sensor's sensitivity. First losing electrons through adsorbing O 2 molecules in air and then obtaining electrons through adsorbing H 2 molecules in H 2 , the charge variation of the sensor based on monolayer Pt/Rh-a-MoO 3 is 1.487 e/0.394 e for per O 2 /H 2 , which suggests that the sensor may have higher sensitivity and lower detection limit. The larger charge variation is also confirmed by the shift of the Fermi level towards the higher energy direction after adsorbing H 2 .

Barium hexaferrite BaFe12O19 (BaM) nanoplates have been synthesized by using a combined sol-gel technique and molten salt method through high-temperature calcination. The components, morphology, and magnetic and microwave absorption properties of BaM were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometry (VSM), and vector network analysis (VNA). The experimental results indicate that the obtained nanoplates exhibit the smallest average grain size and the highest saturation magnetization strength at the calcination temperature with 950(degrees)C. Meanwhile, the electromagnetic adsorption parameters show that the obtained nanoplates reach the maximum reflection loss value of -56.79 dB at 1.74 mm and the maximum effective absorption bandwidth of 4.01 GHz at 2.5 mm. The dielectric and magnetic loss tangent curves demonstrate that the mechanism of dielectric loss is mainly dominated by the nano intrinsic effect of these nanoplates. The remarkable microwave absorption property of the BaM nanoplates demonstrates their significant potential for application in advanced microwave absorption devices.

The lack of active sites and the low availability of photoelectrons severely limit the photocatalytic reduction of nitrogen to ammonia in semiconductor materials. Here, we successfully designed a BiOBr/O-v-TiO2-Cu heterojunction catalyst toward N-2 fixation into NH3. The optimized BiOBr/O-v-TiO2-Cu heterojunction has a promising photocatalytic performance and stability with the highest NH3 yield of 259.82 mu mol center dot g(-1)center dot h(-1). The combination of detailed theoretical simulation calculations and comprehensive characterizations indicates the BiOBr/O-v-TiO2-Cu heterojunction with oxygen vacancy (O-v) stabilized Cu nanoparticles (NPs) as active sites can effectively adsorb and activate N-2 molecules. The close contact between BiOBr and O-v-TiO2 elevates the quick transmission of photogenerated electrons at the interface and the enrichment on Cu NPs. This work not only provides an efficient photocatalyst for the N-2 reduction, but also supplies theoretical support for identifying the active sites and charge transfer kinetics of the nitrogen reduction reaction.

High-performance H2 gas sensors based on monolayer 2D metal oxide α-MoO3 doped with Pt/Rh has been predicted. With a binding energy of −5.262 eV/−5.877 eV, the substitutional doping of Pt/Rh for Mo is a stable doping. After adsorbing O2 in air, the band gap of Pt/Rh-α-MoO3 decreases by 0.62 eV/0.51 eV due to the appearance of the impurity levels and the band narrowing effect. Due to such large decrease, electrons in the valence band can be excited more easily into the conduction band to produce more O2(ads)−, which would oxidize more H2 to generate H2O or hydroxyl along with releasing more electrons to the sensor and increasing the sensor’s sensitivity. First losing electrons through adsorbing O2 molecules in air and then obtaining electrons through adsorbing H2 molecules in H2, the charge variation of the sensor based on monolayer Pt/Rh-α-MoO3 is 1.487 e/0.394 e for per O2/H2, which suggests that the sensor may have higher sensitivity and lower detection limit. The larger charge variation is also confirmed by the shift of the Fermi level towards the higher energy direction after adsorbing H2.

Impurity doping is a necessary technology for the application of semiconductor materials in microelectronic devices. The quantification of doping effects is crucial for controlling the transport properties of semiconductors. Here, taking two-dimensional (2D) hexagonal boron phosphide semiconductor as an example, we employ coherent potential approximation method to investigate the electronic properties of 2D semiconductor materials at low doping concentrations, which cannot be exploited with conventional density function theory. The results demonstrate that the positive or negative impurity potential in 2D semiconductors determines whether it is p-type or n-type doping, while the impurity potential strength decides whether it is shallow-level or deep-level doping. Impurity concentration has important impacts on not only the intensity but also the broadening of impurity peak in band gap. Importantly, we provide the operating temperature range of hexagonal boron phosphide as a semiconductor device under different impurity concentrations and impurity potentials. The methodology of this study can be applied to other 2D semiconductors, which is of great significance for quantitative research on the application of 2D semiconductors for electronic devices.

Gd–Al–Co-doped BaFe12−3x(GdAlCo)xO19 (x = 0, 0.1, 0.2, 0.3, 0.4) was synthesized via the hydrothermal method. We performed comprehensive characterization using XRD, SEM, BET, VSM, XPS, and VNA techniques to explore the impact of substituting magnetic Co2+, Gd3+, and nonmagnetic Al3+ for Fe3+ on the morphology, specific surface area, magnetic, and microwave absorption (MWA) properties of BaFe12−3x(GdAlCo)xO19. Investigating the MWA properties of BaFe12−3x(GdAlCo)xO19 in the 2–18 GHz range, we find that all doped samples demonstrate excellent MWA characteristics. The sample BaFe11.1(GdAlCo)0.3O19 achieves a minimum reflection loss (RLmin) of − 48.13 dB at a thickness of 2.07 mm, indicating an absorption of over 99 % of incident microwaves. The effective absorption bandwidth (EAB) for all four groups of doped samples exceeds 5.98 GHz. Notably, the x  = 0.1 samples reach an EAB of 9.15 GHz at only 2.0 mm thickness, covering most of the X-band and the entire Ku band. Gd-Al-Co co doping of BaFe12O19 not only improves its reflection loss ability, but also increases its absorption bandwidth. Improved the drawbacks of narrow bandwidth and poor loss capability in BaFe12O19. Consequently, BaFe12−3x(GdAlCo)xO19 material shows significant potential for practical applications.

Formaldehyde (CH2O) is an indoor hazardous gas and a respiratory marker for lung cancer patients, thus its adsorption and detection are of particular significance. 2H-MoS2 has a wide range of applications in gas sensors. However, its pristine form is chemically inert and not suitable for the adsorption and detection of CH2O. Here, we systematically investigated the adsorption and gas-sensing properties of defective 2H-MoS2 to CH2O based on first-principles calculations. The S vacancy, substitutional doping and adsorption of transition-metal (TM) atoms in the MoS2 monolayer are considered. We find that the S vacancy effectively enhances the adsorption of CH2O and results in significant charge transfer. The substitutional doping of TM atoms on both S and Mo sites is hard to form in equilibrium conditions for the high formation energy. The adsorption of TM atoms on MoS2 can easily occur for the rather low adsorption energy. Cr and Mn energetically prefer to be adsorbed above the S site, while V, Fe, Co, Ni and Cu energetically prefer to be adsorbed above the Mo site. The TM-adsorbed MoS2 can then strongly adsorb CH2O molecules and results in significant charge transfer, acting as a gas-sensing candidate material for the detection and adsorption of CH2O. The adsorption configurations, density of states, adsorption energy, charge transfer and charge density differences are calculated and discussed. These results are of significance to adsorb the toxic CH2O gas and design its gas sensors using MoS2.

The relationship between the intrinsic carrier concentration and temperature in traditional semiconductors has been studied. However, in two-dimensional semiconductors, which are expected to overcome the bottleneck of Moore's law, the distribution of intrinsic carrier concentrations remains unclear. Here, we employ first-principles calculations to investigate the correlation between carrier concentration and temperature in several two-dimensional semiconductors, including molybdenum disulfide, hexagonal boron phosphide, black phosphorus, zirconium diiodide, tin telluride and hexagonal boron antimonide. On the basis of the parabolic band dispersion, we theoretically derive analytical forms for carrier concentration. Combining with numerical results and analytical forms, we calculate effective mass of charge carriers and obtain the effective density of states function in the conduction band and the valence band at room temperature. Furthermore, we identify the range of impurity concentration required for fabricating doped semiconductor devices. Our investigation provides a theoretical basis for the application of two-dimensional semiconductors in devices.