Coupling the valley degree of freedom to antiferromagnetic order

Conventional electronics are based invariably on the intrinsic degrees of freedom of an electron, namely, its charge and spin. The exploration of novel electronic degrees of freedom has important implications in both basic quantum physics and advanced information technology. Valley as a new electronic degree of freedom has received considerable attention in recent years. In this paper, we develop the theory of spin and valley physics of an antiferromagnetic honeycomb lattice. We show that by coupling the valley degree of freedom to antiferromagnetic order, there is an emergent electronic degree of freedom characterized by the product of spin and valley indices, which leads to spin-valley dependent optical selection rule and Berry curvature-induced topological quantum transport. These properties will enable optical polarization in the spin-valley space, and electrical detection/manipulation through the induced spin, valley and charge fluxes. The domain walls of an antiferromagnetic honeycomb lattice harbors valley-protected edge states that support spin-dependent transport. Finally, we employ first principles calculations to show that the proposed optoelectronic properties can be realized in antiferromagnetic manganese chalcogenophosphates (MnPX_3, X = S, Se) in monolayer form.Comment: 6 pages, 5 figure

Saturated ground vibration analysis based on a three-dimensional coupled train-track-soil interaction model

A novel three-dimensional (3D) coupled train-track-soil interaction model is developed based on the multi-body simulation (MBS) principle and finite element modeling (FEM) theory using LS-DYNA. The novel model is capable of determining the highspeed effects of trains on track and foundation. The soils in this model are treated as saturated media. The wheel-rail dynamic interactions under the track irregularity are developed based on the Hertz contact theory. This model was validated by comparing its numerical results with experimental results obtained from field measurements and a good agreement was established. The one-layered saturated soil model is firstly developed to investigate the vibration responses of pore water pressures, effective and total stresses, and displacements of soils under different train speeds and soil moduli. The multi-layered soils with and without piles are then developed to highlight the influences of multi-layered soils and piles on the ground vibration responses. The effects of water on the train-track dynamic interactions are also presented. The original insight from this study provides a new and better understanding into saturated ground vibration responses in high-speed railway systems using slab tracks in practice. This insight will help track engineers to inspect, maintain, and improve soil conditions effectively, resulting in a seamless railway operation

Dynamic response of water saturated subgrade surface layer under high speed train using moving element method

Since the moving element method (MEM) is an elegant method for solving problems involving moving loads. This paper extends the moving element method to the dynamic response of the water-saturated subgrade surface layer under a high-speed train. The track model is described as the Euler beam to simulate the rail, concrete slab layer and elastic medium to simulate the concrete base layer. The water-saturated subgrade surface layer is characterized by Biot’s dynamic poroelastic theory, and the other subgrade components are regarded as elastic medium. The governing equations are formulated in a coordinate system traveling at a constant velocity, and the associated finite element formulation in a moving frame of reference is derived. The proposed computational scheme is applied to investigate the dynamic characteristics of the water-saturated subgrade surface layer subjected to the moving train load. The effects of various key parameters including the train velocity, permeability, drainage boundary, elastic modulus and rail irregularity on hydro-mechanical response of the saturated subgrade surface layer are carefully analyzed

Generation of ultrabrilliant polarized attosecond electron bunch via dual-wake injection

Laser wakefield acceleration is paving the way for the next generation of electron accelerators, for their own sake and as radiation sources. A dual-wake injection scheme is put forward here to generate an ultrabrilliant polarized attosecond electron bunch, employing a radially polarized laser as a driver. We find that the laser-modulated fields in the plasma, formed in the dual wakes excited by both transverse and longitudinal components of the laser field in the quasi-blowout regime, facilitate the attosecond injection of a transversely beamed Clover-like electron bunch. Initial spin directions of the generated attosecond electrons can be reversed collectively due to the laser-assisted spin precessions, which significantly mitigates the drastic depolarization of the sheath electrons in the strongly nonlinear plasma wake. In our three-dimensional particle-in-cell simulations, an electron bunch, with $\sim300$ as duration, six-dimensional brightness of $\sim10^{14}$ $A/m^2/0.1\%$ and $\sim90\%$ polarization can be generated using a few terawatt laser and a shock-front plasma density. Such an electron bunch could play an essential role in many applications, such as ultrafast imaging, nuclear structure studies, and the operation of coherent radiation sources

Inhibitory effect of lotus seedpod oligomeric procyanidins on advanced glycation end product formation in a lactose\u2013lysine model system

Background:Industrial food processing induces protein glycation modifications and toxic advanced glycation end products (AGEs) which affect human health. Therefore, it is of interest to monitor AGEs in food processing. The present study was carried out to investigate the influence of lotus seedpod oligomeric procyanidin (LSOPC) concentrations, solution pH value and metal ions on AGE formation by heat treatment of lactose\u2013lysine model solutions. N\u3b5-(carboxymethyl) lysine (CML), as one of the common AGEs was also determined by HPLC\u2013MS/MS in this experiment. Results: The results showed that LSOPC can inhibit the formation of AGEs effectively at higher concentrations, lower temperature, and it can reverse the promotion function of metal ions because of its high inhibition activity. Also, LSOPC can inhibit CML formation in the Maillard reaction as well. Conclusion: These results indicated that LSOPC could be used as functional food ingredients to inhibit AGE formation

Safety and Efficacy of Anti-PD-1 Monoclonal Antibodies in Patients With Relapsed or Refractory Lymphoma: A Meta-Analysis of Prospective Clinic Trails

Background: Immune checkpoint inhibition therapy with monoclonal antibody against programmed cell death protein 1 (PD-1), including nivolumab and pembrolizumab, has demonstrated powerful clinical efficacy in the treatment of advanced cancers. However, there is no evidence-based systematic review on the safety and efficacy of anti-PD-1 antibody in treating lymphoma.Methods: To evaluate the safety and efficacy of nivolumab/pembrolizumab, we analyzed clinical trials from PUBMED, EMBASE, and The Cochrane Library. For safety analysis, the incidence and exhibition of any grade and grade ≥3 adverse events (AEs) were evaluated. Overall response rate (ORR), 6-month progression-free survival (PFS) and 6-month overall survival (OS) were calculated for efficacy analysis.Results: Overall ten studies and 718 patients (114 non-Hodgkin lymphomas, 604 Hodgkin lymphomas) were enrolled, including 4 phase I studies and 6 phase II studies. The pooled incidences of any grade and grade ≥3 adverse events (AEs) were 74 and 24%, respectively. Drug-related deaths occurred in two patients. The most common any grade AEs were fatigue (14.91%), rash (14.8%), hypothyroidism (13.77%), platelet count decreased (13.54%), pyrexia (13%). The most common grade ≥3 AEs were neutropenia (4.79%), pneumonitis (3.58%), rash (3.38%), and leukopenia (3.31%). Fatigue (p = 0.0072) and rash (p = 0.0078) in any grade AEs were less observed in patients treated with pembrolizumab than nivolumab. The pooled ORR, PFS rate and OS rate were 58, 73, and 96%, respectively. The ORR in patients with Hodgkin lymphomas (HL) was higher than patients with non-Hodgkin lymphomas (NHL) (69.08 vs. 30.77%, p < 0.0001). However, there was no significant difference of efficacy between nivolumab and pembrolizumab.Conclusions: Nivolumab and pembrolizumab have promising outcomes with tolerable AEs and drug-related deaths in patients with relapsed or refractory lymphoma. Pembrolizumab caused less any grade AEs like fatigue and rash than nivolumab. Patients with HL got better response than NHL