Search

The giant spin–orbit torque (SOT) generated by topological surface states in topological insulators (TIs) provides an energy-efficient writing method for magnetic memory. In this study, we demonstrate a topological insulator/spin valve (TI/SV) device that operates at room temperature. An ultrathin, high-quality TI (Bi0.5Sb0.5)2Te3 (BST) thin film is epitaxially grown as a functional layer on a (0001)-Al2O3 substrate via molecular beam epitaxy in ultrahigh vacuum. Subsequently, Ta/CoFe/Cu/CoFe/IrMn layers are grown on BST/Al2O3 thin films using magnetron sputtering to form TI/SV devices via a subsequent standard lithography process. The resulting TI/SV devices exhibit a giant magnetoresistance of up to ∼1.1% at room temperature. Additionally, a low switching current density of approximately 1.25 × 105 A cm−2 is achieved, which implies high potential for further reducing the energy consumption of SOT-based devices. The SOT conversion efficiency and charge-spin conversion efficiency of the TI layer are approximately 4.74 × 10−6 Oe A−1 cm2 and 1.33, respectively, as extracted from the SOT-induced shift of the magnetic switching field. Moreover, the switching current density reduces steadily with the device size scaling down. This study can facilitate the realization of energy-efficient magnetic memory devices in the future. [ABSTRACT FROM AUTHOR]

The effects of low-frequency electromagnetic casting (LFEC) on the microstructure and tensile properties of 5A90 Al–Mg–Li alloy with and without minor Sc were investigated. In addition to minor Sc, the refined microstructures of the conventional direct chill cast (DCC) alloy and the microstructures of the as-cast alloy were refined further and more equiaxed grains formed in LFEC ingots with Sc. Higher density, smaller size, and more uniform distribution Al3(Sc, Zr) in the aged alloy with Sc induced by LFEC, which pins on grain boundaries, can effectively inhibit recrystallization. As a result, it had been a significant improvement in strength which was mainly due to the Orowan effect of Al3(Sc, Zr) dispersoids combined with grain refinement. The ultimate tensile strength of 565.4 MPa, yield strength of 475.3 MPa, and the corresponding elongation of 6.4% were obtained in the as-aged 5A90 alloy with 0.15 wt% Sc cast by LFEC at 10 Hz and 100 A.

To determine the interactions between TNT and aniline adsorptions and the potential to enhance their transports in saturated Chinese loess, batch and column tests were conducted. The batch tests show that their adsorptions inhibit each other when they coexist, and their inhibitions depend on their concentrations, implying that their coexistence has the potential to enhance their transports of each other in the saturated loess. The column tests confirm this speculation, while aniline enhances TNT transport more obviously than TNT does. These findings are ascribed to TNT adsorption being primarily through surface adsorption, while aniline adsorption mainly takes place via electrostatic adsorption and inner pore diffusion adsorption, as well as surface adsorption. There is a certain competitive relationship in their adsorptions on the loess because they have same and different adsorption sites; in particular, electrostatic force is greater than surface force. Therefore, these inhibitions on adsorption are conducive to the existences of TNT and aniline in the water rather than being fixed on the loess, thus enhancing their transports in the saturated loess, indicating that their coexistence can increase the risk of soil and even groundwater pollution. [ABSTRACT FROM AUTHOR]

In this paper, a one-dimensional (1-D) range profile of the hypersonic target enveloped by a plasma sheath is investigated. Firstly, the non-uniform property of the plasma sheath is studied and its impact on the wideband electromagnetic (EM) wave is analyzed. A wideband radar echo model for the plasma-sheath-enveloped hypersonic target is constructed. Then, by exploiting the relationship among the incident depth, reflection intensity, and plasma velocity, it reveals that distinct scatter points in various areas of the target will suffer from varying reflection intensity and coupled velocity, leading to severe defocusing in the range profile. To tackle this issue, a novel focusing algorithm combing the Fractional Fourier Transform (FRFT) with the CLEAN technique is developed, which independently calculates the coupled plasma velocity and compensates for the phase error via a series of iterative procedures. Finally, the influence of the plasma sheath on the 1-D range profile and the effectiveness of the proposed focusing algorithm are validated through simulations. [ABSTRACT FROM AUTHOR]

Thermophilic β-1,4-endoglucanases (Cel5A) have garnered significant interest due to their potential applications in various industries, particularly in biofuel production and biorefineries. However, despite inherent stability, thermophilic Cel5A still face challenges in terms of further enhancing their catalytic efficiency and thermostability. In this study, a novel B-factor analysis method was used to predict beneficial amino acid substitutions within a 4 Å radius of the catalytic site in the tunnel of thermophilic Cel5A from Acidomyces richmondensis (ArCel5A). A combined strategy involving site-saturation mutagenesis and high-throughput screening was employed to identify the variants with the highest endoglucanase activity. Genomic sequencing revealed a mutation at position 299 in the starting strain T. reesei A2H, where the nucleotide sequence changed from TAC to TGC, resulting in a corresponding amino acid substitution from Tyrosine(Y) to Cystine(C). The endoglucanase activity of the mutant ArCel5A reached 3251 IU/mL, representing an 85.2% increase compared to wild-type ArCel5A at the fermentation time of 94 h. Significantly, the ArCel5A-Y299C mutant showed superior thermostability, retaining 93.8% of its initial activity after 30 min at 70 °C, and 91.5% after 10 min at 80 °C. Various computational simulation methods confirmed that the Y299C mutation enhanced the stability of the catalytic pocket, thereby improving the overall stability and catalytic efficiency of ArCel5A. This study offers an effective strategy for mining target sites for rational mutagenesis based on highly conserved sequences, which simultaneously improves both the thermostability and catalytic efficiency of thermophilic Cel5A. [ABSTRACT FROM AUTHOR]