The positive exchange bias property with hopping switching behavior in van der Waals magnet FeGeTe

The magnetic exchange bias effect is one of the representative interlayer magnetic coupling phenomena and is widely utilized in numerous technological applications. However, its mechanism is still elusive even in a simple magnetic bilayered system because of the complex interface magnetic orders. Van der Waals layered magnetic materials may provide an essential platform for deeply understanding the detailed mechanism of the exchange bias owing to its ideal interface structure. Here we first observed the positive exchange-biased anomalous Hall effect (AHE) with a hopping switching behavior in the FeGeTe Van der Waals nano-flakes. After systemically studying the cooling field dependence properties of the exchange bias effect, we propose that the coexistence of stable and frustrated surface magnetization of the antiferromagnetic phase will modify the total interface coupling energy density between the ferromagnetic (FM) and antiferromagnetic (AFM) phases. This model could provide a consistent description for such unusual exchange bias effect based on microspin simulation.

Global phosphoproteomic profiling of skeletal muscle in ovarian hormone-deficient female mice

Dynapenia, the age-related loss of skeletal muscle strength without the loss of muscle mass, significantly impacts the activities and quality of life of the aging population. Studies have shown that dynapenia occurs earlier in females than males in both human and rodent studies. Moreover, in females, estrogen deficiency has been shown to contribute to the loss of skeletal muscle strength as well as blunted recovery of strength after injury. The maintenance of skeletal muscle contractile function is vital to the overall health of women, especially as women live 1/3 of their life in an estrogen deficient state. Reversible protein phosphorylation is an indispensable post-translational modification, playing a key role in signal transduction pathways. Phosphorylation of skeletal muscle proteins have been shown to regulate sarcomeric function, excitation-contraction coupling, energy metabolism, and fiber-type composition. To define the physiological changes in the skeletal muscle phosphoproteome associated with estrogen deficiency, we used an ovariectomy model coupled with mass spectrometry. We identified, in total, 5,424 unique phosphorylation sites and 1,177 phosphoproteins in the tibialis anterior muscle. Ingenuity Pathway Analysis show decreased phosphorylation of contractile proteins and significant predicted inhibition of the upstream kinase, CDK6 (z-score -2.0) in ovariectomized compared to control muscles. Our results suggest that estrogen deficiency remodels the skeletal muscle phosphoproteome which may alter phosphorylation signaling that might contribute to the loss of strength in females.

Cross correlation mediated by Majorana island with finite charging energy

Based on the many-particle-number-state treatment for transport through a pair of Majorana zero modes (MZMs) which are coupled to the leads via two quantum dots, we identify that the reason for zero cross correlation of currents at uncoupling limit between the MZMs is from a degeneracy of the teleportation and the Andreev process channels. We then propose a scheme to eliminate the degeneracy by introducing finite charging energy on the Majorana island which allows for coexistence of the two channels. We find nonzero cross correlation established even in the Majorana uncoupling limit (and also in the small charging energy limit), which demonstrates well the teleportation or nonlocal nature of the MZMs. More specifically, the characteristic structure of coherent peaks in the power spectrum of the cross correlation is analyzed to identify the nonlocal and coherent coupling mechanism between the MZMs and the quantum dots. We also display the behaviors of peak shift with variation of the Majorana coupling energy, which can be realized by modulating parameters such as the magnetic field.

A Review on Ultrasonic-Assisted Forming: Mechanism, Model, and Process

Compared with conventional forming processes, ultrasonic-assisted forming technology with a high frequency and small amplitude can significantly improve the forming quality of materials. Owing to the advantages of reduced forming force, improved surface quality, avoidance of forming defects, and strengthened surface structure, ultrasonic-assisted forming technology has been applied to increasingly advanced forming processes, such as incremental forming, spinning, and micro-forming. However, in the ultrasonic-assisted forming process, there are multiple ultrasonic mechanisms, such as the volume effect and surface effect. The explanation of the effect of ultrasonic vibration (UV) on plastic deformation remains controversial, hindering the development of related technologies. Recently, many researchers have proposed many new theories and technologies for ultrasonic-assisted forming. To summarize these developments, systematic discussions on mechanisms, theoretical models, and forming performances are provided in this review. On this basis, the limitations of the current study are discussed. In addition, an outlook for ultrasonic-assisted forming is proposed: efficient and stable UV systems, difficulty forming components with complex geometry, explanation of the in-depth mechanism, a systematic theoretical prediction model, and multi-field-coupling energy-assisted forming are considered to be hot spots in future studies. The present review enhances existing knowledge of ultrasonic-assisted forming, and facilitates a fast reference for related researchers.

Discussion on the Feasibility of the Integration of Wind Power and Coal Chemical Industries for Hydrogen Production

To improve the utilization rate of the energy industry and reduce high energy consumption and pollution caused by coal chemical industries in northwestern China, a planning scheme of a wind-coal coupling energy system was developed. This scheme involved the analysis method, evaluation criteria, planning method, and optimization operation check for the integration of a comprehensive evaluation framework. A system was established to plan the total cycle revenue to maximize the net present value of the goal programming model and overcome challenges associated with the development of new forms of energy. Subsequently, the proposed scheme is demonstrated using a 500-MW wind farm. The annual capacity of a coal-to-methanol system is 50,000. Results show that the reliability of the wind farm capacity and the investment subject are the main factors affecting the feasibility of the wind-coal coupled system. Wind power hydrogen production generates O2 and H2, which are used for methanol preparation and electricity production in coal chemical systems, respectively. Considering electricity price constraints and environmental benefits, a methanol production plant can construct its own wind farm, matching its output to facilitate a more economical wind-coal coupled system. Owing to the high investment cost of wind power plants, an incentive mechanism for saving energy and reducing emissions should be provided for the wind-coal coupled system to ensure economic feasibility and promote clean energy transformation.

What is the Impact of Energy Expenditure on Energy Intake?

Coupling energy intake (EI) to increases in energy expenditure (EE) may be adaptively, compensatorily, or maladaptively leading to weight gain. This narrative review examines if functioning of the homeostatic responses depends on the type of physiological perturbations in EE (e.g., due to exercise, sleep, temperature, or growth), or if it is influenced by protein intake, or the extent, duration, timing, and frequency of EE. As different measures to increase EE could convey discrepant neuronal or humoral signals that help to control food intake, the coupling of EI to EE could be tight or loose, which implies that some ways to increase EE may have advantages for body weight regulation. Exercise, physical activity, heat exposure, and a high protein intake favor weight loss, whereas an increase in EE due to cold exposure or sleep loss likely contributes to an overcompensation of EI, especially in vulnerable thrifty phenotypes, as well as under obesogenic environmental conditions, such as energy dense high fat—high carbohydrate diets. Irrespective of the type of EE, transient elevations in the metabolic rate seem to be general risk factors for weight gain, because a subsequent decrease in energy requirement is not compensated by an adequate adaptation of appetite and EI.

Design of ZnO-Drug Nanocarriers against the Main Protease of SARS-CoV-2 (COVID-19): An In Silico Assay

The treatment of coronavirus diseases (COVID-19) is a principal aim worldwide that is required restore public health in the population. To this end, we have been studied several kinds of de novo and repurposed drugs to investigate their ability to inhibit the replication of the virus which causes the current pandemic—the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, finding a vehicle that promotes the controlled dosage is vital for avoiding secondary effects. For this reason, the present work exposes a nanostructured carrier based on ZnO, which is coupled to three repurposed drugs (Chloroquine, Dipyridamole, and Lopinavir) to understand the chemical interaction of the formed composite. The designed composites are modeled and optimized using the DFT formalism. In obtaining exergonic adsorption energies, we found values between 0.582 to 2.084 eV, depending on the used drug. At the same time, the HOMO orbitals demonstrate the electronic overlap between the ZnO-Np and the Lopinavir, which is the molecule with the higher adsorption energy. Finally, we carried out a docking assay to investigate the interaction of free drugs and composites with the main protease of the SARS-CoV-2, finding that the coupling energy of the composites (at around to 0.03 eV) was higher, compared with the free drugs. As such, our results suggest a controlled dosage of the drug on the SARS-CoV-2 target.

Excitonic coupling directly revealed on single chains of polyfluorene by combined force spectroscopy and fluorescence microscopy

Molecular aggregates were discovered in 1930’s, yet, the forces and excitonic coupling energy associated with the aggregate formation have not been detected so far. We directly measure such force and energy on single chains of the conjugated polymer polyfluorene using atomic force and fluorescence microscopes. The polyfluorene chain is attached on either side to a substrate and an AFM tip, respectively, and mechanically stretched under intense laser irradiation. The force – extension curves show force peaks that are attributed to gradual unfolding of the chain. Upon the irradiation, neighboring conjugated segments interact via excitonic coupling when in contact and experience an attractive force which is detected by the AFM. Analysis of the force curves provides excitonic coupling energy which is of same order as theoretically calculated values for a face-to-face fluorene dimer, and in agreement with the energy obtained from single-chain fluorescence spectra. Apart from contributing an essential piece of knowledge in the field of molecular photophysics, the work demonstrates on molecular scale a novel energy conversion mechanism from light to mechanical energy which could be potentially used, e.g., as a driving mechanism for molecular motors.

The optical response of artificially twisted MoS$$_2$$ bilayers

Two-dimensional layered materials offer the possibility to create artificial vertically stacked structures possessing an additional degree of freedom—theinterlayertwist. We present a comprehensive optical study of artificially stacked bilayers (BLs) MoS$$_2$$ 2 encapsulated in hexagonal BN with interlayer twist angle ranging from 0$$^{\circ }$$ ∘ to 60$$^{\circ }$$ ∘ using Raman scattering and photoluminescence spectroscopies. It is found that the strength of the interlayer coupling in the studied BLs can be estimated using the energy dependence of indirect emission versus the A$$_\text {1g}$$ 1g –E$$_\text {2g}^1$$ 2g 1 energy separation. Due to the hybridization of electronic states in the valence band, the emission line related to the interlayer exciton is apparent in both the natural (2H) and artificial (62$$^\circ $$ ∘ ) MoS$$_2$$ 2 BLs, while it is absent in the structures with other twist angles. The interlayer coupling energy is estimated to be of about 50 meV. The effect of temperature on energies and intensities of the direct and indirect emission lines in MoS$$_2$$ 2 BLs is also quantified.

Josephson Currents and Gap Enhancement in Graph Arrays of Superconductive Islands

Evidence is reported that topological effects in graph-shaped arrays of superconducting islands can condition superconducting energy gap and transition temperature. The carriers giving rise to the new phase are couples of electrons (Cooper pairs) which, in the superconducting state, behave as predicted for bosons in our structures. The presented results have been obtained both on star and double comb-shaped arrays and the coupling between the islands is provided by Josephson junctions whose potential can be tuned by external magnetic field or temperature. Our peculiar technique for probing distribution on the islands is such that the hopping of bosons between the different islands occurs because their thermal energy is of the same order of the Josephson coupling energy between the islands. Both for star and double comb graph topologies the results are in qualitative and quantitative agreement with theoretical predictions.