Josephson dynamics of a spin-orbit coupled Bose-Einstein condensate in a double well potential

We investigate the quantum dynamics of an experimentally realized spin-orbit coupled Bose-Einstein condensate in a double well potential. The spin-orbit coupling can significantly enhance the atomic inter-well tunneling. We find the coexistence of internal and external Josephson effects in the system, which are moreover inherently coupled in a complicated form even in the absence of interatomic interactions. Moreover, we show that the spin-dependent tunneling between two wells can induce a net atomic spin current referred as spin Josephson effects. Such novel spin Josephson effects can be observable for realistically experimental conditions.Comment: 8 page

van der Waals Stacking-Induced Topological Phase Transition in Layered Ternary Transition Metal Chalcogenides

Novel materials with nontrivial electronic and photonic band topology are crucial for realizing novel devices with low power consumption and heat dissipation and quantum computing free of decoherence. Here, we theoretically predict a novel class of ternary transition metal chalcogenides that exhibit dual topological characteristics, quantum spin Hall insulators (QSHIs) in their two-dimensional (2D) monolayers and topological Weyl semimetals in their 3D noncentrosymmetric crystals upon van der Waals (vdW) stacking. Remarkably, we find that one can create and annihilate Weyl fermions and realize the transition between Type-I and Type-II Weyl fermions by tuning vdW interlayer spacing, providing the missing physical picture of the evolution from 2D QSHIs to 3D Weyl semimetals. Our results also show that these materials possess excellent thermodynamic stability and weak interlayer binding; some of them were synthesized two decades ago, implying their great potentials for experimental synthesis, characterization, and vdW heterostacking. Moreover, their ternary nature will offer more tunability for electronic structure by controlling different stoichiometry and valence charges. Our findings provide an ideal materials platform for realizing QSH effect and exploring fundamental topological phase transition and will open up a variety of new opportunities for two-dimensional materials and topological materials research.National Science Foundation (U.S.). Materials Research Science and Engineering Centers (Program) (Award DMR-1419807)United States. Department of Energy. Division of Materials Sciences and Engineering (Award DE-SC0010526

Hypergraph-based saliency map generation with potential region-of-interest approximation and validation

Author name used in this publication: Zheru ChiAuthor name used in this publication: Dagan Feng2011-2012 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Conformational dynamics of a membrane protein chaperone enables spatially regulated substrate capture and release

Membrane protein biogenesis poses enormous challenges to cellular protein homeostasis and requires effective molecular chaperones. Compared with chaperones that promote soluble protein folding, membrane protein chaperones require tight spatiotemporal coordination of their substrate binding and release cycles. Here we define the chaperone cycle for cpSRP43, which protects the largest family of membrane proteins, the light harvesting chlorophyll a/b-binding proteins (LHCPs), during their delivery. Biochemical and NMR analyses demonstrate that cpSRP43 samples three distinct conformations. The stromal factor cpSRP54 drives cpSRP43 to the active state, allowing it to tightly bind substrate in the aqueous compartment. Bidentate interactions with the Alb3 translocase drive cpSRP43 to a partially inactive state, triggering selective release of LHCP’s transmembrane domains in a productive unloading complex at the membrane. Our work demonstrates how the intrinsic conformational dynamics of a chaperone enables spatially coordinated substrate capture and release, which may be general to other ATP-independent chaperone systems

Flexible Printed Circuit Board as Novel Electrodes for Acoustofluidic Devices

Surface acoustic wave (SAW) based acoustofluidics shows broad applications in biomedicine and chemistry. Conventional manufacturing process for SAW devices uses photolithography and metal deposition, thus requires accessing cleanroom facilities. This study presents an efficient and versatile technique based on a flexible printed circuit board (FPCB) for developing SAW acoustofluidic devices. By mechanically clamping interdigital electrodes (IDEs) made on the FPCB onto a piezoelectric substrate, SAWs can be effectively generated with an additional matching network. The SAW amplitudes was measured by a laser vibrometer, which increases with the applied input voltage. The FPCB-SAW device has been applied to actuate 10-m microspheres to form strong streaming vortices inside a droplet, and to drive a sessile droplet for transportation on the substrate surface. The use of the FPCB rather than a rigid PCB can help cut down on the overall footprint of the device and save space. The low requirement in assembling the FPCB-SAW device can facilitate versatile acoustofluidic applications by providing fast prototyping devices.This work was supported in part by the Natural Science Basic Research Program of Shaanxi Province (2020JQ-233), Fundamental Scientific Research of Central Universities (3102017OQD116), Engineering and Physical Sciences Research Council fellowship (EP/P002803/1 and EP/P018998/1), Global Challenges Research Fund, and the Royal Society (IEC/NSFC/170142, IE161019)

Enhancement of collapse-resistant capacity of non-seismically designed RC frames using various CFRP strengthening schemes

The existing studies have demonstrated relatively weak robustness of non-seismically designed reinforced concrete (RC) frames against collapse than seismically designed RC frames, causing the demand of efficient strengthening schemes to enhance their collapse-resistant capacity. Therefore, this paper presents an experimental program aiming at strengthening the collapse-resistant capacity of non-seismically designed RC frames using carbon fiber reinforced polymer (CFRP). A total of seven sub-frames were tested, of which the penultimate column or edge column was notionally removed to replicate the initial damage caused by accidental loads. Two sub-frames without strengthening were tested first as reference tests. Similar to existing research outcomes, the referential sub-frames experienced premature rebar fracture at the beam ends near the removed column, resulting in a severe softening in load resistance. Whilst the load resistance could reascend, the fracture of the rebar at the beam ends near the side columns only allowed an insufficient mobilization of catenary action (CA). In addition, the side joint of the referential sub-frame representing a penultimate column removal scenario suffered significant damage. Subsequently, five strengthening schemes were applied to the referential sub-frame, they are designed to increase the compressive arch action (CAA) capacity or CA capacity, or both the CAA and CA capacities through CFRP strengthening. Test results demonstrated that the proposed strengthening schemes in this paper can efficiently increase the load resistance at the CAA and CA stages but failed to mitigate the severe load resistance softening. The strengthening scheme planned to increase the CAA capacity unexpectedly decreased the deformation capacity of the strengthened sub-frame due to premature fracture of beam rebar near the side columns. The strengthening schemes planned to increase the CA capacity or both the CAA and CA capacities could increase not only the CAA capacity but also the CA capacity. The enhanced load resistance at the CA stage was mainly attributed to the continuous CFRP strips attached to the soffits. Unfortunately, the energy method demonstrated that the dynamic load resistance of the tested sub-frames to prevent collapse was achieved at the CAA stage rather than the CA stage because of the severe load resistance softening. Thus, the efforts devoted to increasing the CA capacity by this paper were valid in a real collapse of building scenario. In addition, 113 available test results were collected to compare with the acceptance criteria in existing codes for collapse-resistant design. Based on the test results and comparison, design suggestions were given for the collapse-resistant design

Non-Abelian Collective Excitations in Unlinearized Quark-Gluon Plasma Media

We study the effect of unlinearized medium on the collective excitations in quark-gluon plasma. We present two kinds of non-Abelian oscillation solutions which respectively correspond to weakly and strongly nonlinear coupling of field components in color space. We also show that the weakly nonlinear solution is similar to Abelian-like one but has the frequency shift, which is of order $g^2T$, from eigenfrequency.Comment: 7 page