Bulk-Fermi-Arc Transition Induced Large Photogalvanic Effect in Weyl Semimetals

The surface Fermi arc, as a hallmark of Weyl semimetals (WSMs), has been well known in current research, but it remains a challenge to unveil novel phenomena associated with the Fermi arc. Here, we predict a heretofore unrecognized process in WSMs, namely, the photoinduced transition between the bulk states and the Fermi arc. We find this process is significant and can lead to a large effective three-dimensional shift current on the boundaries with the Fermi arc in wide terahertz range. Moreover, due to the low symmetry of the boundaries, the surface photogalvanic effect predicted here can appear in a large class of WSMs that do not have bulk shift current. Hence, our work not only unveils a hidden photogalvanic effect in WSMs but also suggests that all the WSMs are promising material candidates for developing efficient terahertz photodetectors.Comment: 6 pages, 5 figure

Leonurusine hydrochloride promotes osteogenic differentiation via Wnt/β-catenin pathway and expression of Runx2

Purpose: To investigate the effect of leonurusine hydrochloride (LH) on osteogenic differentiation, and the involvement of Wnt/β-catenin route and runt-associated transcription factor 2 (Runx2) in the process. Methods: Mouse osteogenic precursor cell line MC3T3-E1 was used. The cells were assigned to control and three other groups treated with increasing doses of LH, i.e., 0.1, 1, and 10 μmmol/L. Cellular differentiation was determined in the various groups with respect to mRNA expressions of alkaline phosphatase (ALP), number of calcified nodules, Wnt/β-catenin pathway-related genes, viz, 5 (LRP5),β-catenin, GSK-3β, as well as mRNA expressions of related osteogenic differentiation genes, namely. alkaline phosphatase (ALP), alpha 1 type I collagen (Col1-α), Run×2, and osteogenic-related transcription factor antibody (Osterix) using reverse transcription polymerase chain reaction (RT-PCR). Results: The secretion levels of ALP in cells exposed to LH doses of 1 and 10 μmmol/L were significantly increased, relative to control values (p < 0.05). There were marked increases in mRNA levels of LRP5 and β-catenin in cells treated with LH doses of 1 and 10 μmmol/L compared with the control group, while GSK-3β mRNA expression levels were significantly lower than that in control group(p < 0.05). However, the expression levels of ALP, Col1-α, Run×2, Osterix mRNA in cells exposed to LH at doses of 1 and 10 μmmol/L were significantly higher than the corresponding expression levels in control cells (p < 0.05). Conclusion: Leonurusine hydrochloride may promote osteogenic differentiation and bone mineralization via a mechanism involving activation of the Wnt/β-catenin pathway and up-regulation of Run×2 expression. Keywords: Leonurusine hydrochloride, Wnt/β-catenin, Runx2, Osteogenic differentiatio

A New Guide Lifter for the Transceiver of USBL

A new guide lifter has been put forward for the transceiver of Ultra Short Base Line (USBL) with a worm gear reducer applied as self-locking of the lifter and a chain structure applied to drive the sliding shaft moving up and down. The new device is 7500 mm long and connected to the end of the transceiver. Linear motion products are introduced to ensure the shaft unable to rotate and the position measurements are provided by position sensors. A heavy self-sealing sliding bearing, which is 800 mm in length, keeps the shaft running reliably. Then the three-dimensional model is built and the structure parameters of the lifter are calculated. Later, the working process of the lifter is simulated to guarantee the movement parameters meet the request of USBL. Finally, the experiment on the intensity and stiffness of the lifter is carried out via the finite element model of the lifter built in ANSYS with the maximum load conditions and the result has been experimentally verified. This device provides a reliable approach of operating USBL which plays a vitally important role in ocean exploration and the research results are successfully applied to the scientific research vessels of Dayang No. 1 as well as Xiangyanghong No. 9

Tailoring Dzyaloshinskii-Moriya interaction in a transition metal dichalcogenide by dual-intercalation

Dzyaloshinskii-Moriya interaction (DMI) is vital to form various chiral spin textures, novel behaviors of magnons and permits their potential applications in energy-efficient spintronic devices. Here, we realize a sizable bulk DMI in a transition metal dichalcogenide (TMD) 2H-TaS2 by intercalating Fe atoms, which form the chiral supercells with broken spatial inversion symmetry and also act as the source of magnetic orderings. Using a newly developed protonic gate technology, gate-controlled protons intercalation could further change the carrier density and intensely tune DMI via the Ruderman-Kittel-Kasuya-Yosida mechanism. The resultant giant topological Hall resistivity of 1.4 uohm.cm at -5.2V (about 460% of the zero-bias value) is larger than most of the known magnetic materials. Theoretical analysis indicates that such a large topological Hall effect originates from the two-dimensional Bloch-type chiral spin textures stabilized by DMI, while the large anomalous Hall effect comes from the gapped Dirac nodal lines by spin-orbit interaction. Dual-intercalation in 2HTaS2 provides a model system to reveal the nature of DMI in the large family of TMDs and a promising way of gate tuning of DMI, which further enables an electrical control of the chiral spin textures and related electromagnetic phenomena.Comment: 21 pages, 4 figure

Roles of sex hormones in mediating the causal effect of vitamin D on osteoporosis: A two-step Mendelian randomization study

BackgroundAlthough 25-hydroxyvitamin D [25(OH)D] is a risk factor for osteoporosis, it is not clear whether sex hormones mediate this casual association. We aimed to explore how sex hormones affect the association between 25(OH)D and osteoporosis to provide meaningful insights on the underlying mechanisms from a genetic perspective.MethodsGenetic variations in 25(OH)D, total testosterone (TT), androstenedione (A4), estradiol (E2), and testosterone/17β-estradiol (T/E2) were determined through summary statistics. Taking osteoporosis as the outcome (FinnGen biobank, 332,020 samples), we conducted a Mendelian randomization (MR) analysis to establish the association between 25(OH)D and these sex hormones. The two-step MR analysis quantified the mediatory effects of sex hormones on osteoporosis. The results were further verified by pleiotropy and heterogeneity analyses.ResultsMR results showed that 25(OH)D (OR= 1.27, p = 0.04) and TT (OR= 1.25, p = 0.04) had a causal effect on osteoporosis. No significant associations were observed between the other sex hormones (A4, E2, and T/E2) and osteoporosis (p>0.05). Sensitivity analysis (p>0.05) confirmed the robustness of the MR results. The two-step MR analysis provided evidence that the mediatory effect of TT was 0.014 (the percentage of TT mediation was 5.91%). Moreover, the direct effect of 25(OH)D on osteoporosis was 0.221. A4, E2, and T/E2 were not considered as potential mediators of the role of 25(OH)D as a risk factor for OP.ConclusionThis study, through MR analysis, showed that TT mediates the causal effect of 25(OH)D on osteoporosis. Interventions targeting TT, therefore, have the potential to substantially reduce the burden of osteoporosis attributable to high 25(OH)D