61 research outputs found
Topological magnetoplasmon
Classical wave fields are real-valued, ensuring the wave states at opposite
frequencies and momenta to be inherently identical. Such a particle-hole
symmetry can open up new possibilities for topological phenomena in classical
systems. Here we show that the historically studied two-dimensional (2D)
magnetoplasmon, which bears gapped bulk states and gapless one-way edge states
near zero frequency, is topologically analogous to the 2D topological p+\Ii p
superconductor with chiral Majorana edge states and zero modes. We further
predict a new type of one-way edge magnetoplasmon at the interface of opposite
magnetic domains, and demonstrate the existence of zero-frequency modes bounded
at the peripheries of a hollow disk. These findings can be readily verified in
experiment, and can greatly enrich the topological phases in bosonic and
classical systems.Comment: 12 pages, 6 figures, 1 supporting materia
On-chip picosecond synchrotron pulse shaper
Synchrotrons are powerful and productive in revealing the spatiotemporal
complexities in matter. However, X-ray pulses produced by the synchrotrons are
predetermined in specific patterns and widths, limiting their operational
flexibility and temporal resolution. Here, we introduce the on-chip picosecond
synchrotron pulse shaper that shapes the sub-nm-wavelength hard X-ray pulses at
individual beamlines, flexibly and efficiently beyond the synchrotron pulse
limit. The pulse shaper is developed using the widely available
silicon-on-insulator technology, oscillates in torsional motion at the same
frequency or at harmonics of the storage ring, and manipulates X-ray pulses
through the narrow Bragg peak of the crystalline silicon. Stable pulse
manipulation is achieved by synchronizing the shaper timing to the X-ray timing
using electrostatic closed-loop control. Tunable shaping windows down to 40
are demonstrated, allowing X-ray pulse picking, streaking, and slicing in
the majority of worldwide synchrotrons. The compact, on-chip shaper offers a
simple but versatile approach to boost synchrotron operating flexibility and to
investigate structural dynamics from condensed matter to biological systems
beyond the current synchrotron-source limit
Topological kink plasmons on magnetic-domain boundaries.
Two-dimensional topological materials bearing time reversal-breaking magnetic fields support protected one-way edge modes. Normally, these edge modes adhere to physical edges where material properties change abruptly. However, even in homogeneous materials, topology still permits a unique form of edge modes - kink modes - residing at the domain boundaries of magnetic fields within the materials. This scenario, despite being predicted in theory, has rarely been demonstrated experimentally. Here, we report our observation of topologically-protected high-frequency kink modes - kink magnetoplasmons (KMPs) - in a GaAs/AlGaAs two-dimensional electron gas (2DEG) system. These KMPs arise at a domain boundary projected from an externally-patterned magnetic field onto a uniform 2DEG. They propagate unidirectionally along the boundary, protected by a difference of gap Chern numbers ([Formula: see text]) in the two domains. They exhibit large tunability under an applied magnetic field or gate voltage, and clear signatures of nonreciprocity even under weak-coupling to evanescent photons
Negative longitudinal magnetoresistance in GaAs quantum wells
Negative longitudinal magnetoresistances (NLMRs) have been recently observed
in a variety of topological materials and often considered to be associated
with Weyl fermions that have a defined chirality. Here we report NLMRs in
non-Weyl GaAs quantum wells. In the absence of a magnetic field the quantum
wells show a transition from semiconducting-like to metallic behaviour with
decreasing temperature. We observed pronounced NLMRs up to 9 Tesla at
temperatures above the transition and weak NLMRs in low magnetic fields at
temperatures close to the transition and below 5 K. The observed NLMRs show
various types of magnetic field behaviour resembling those reported in
topological materials. We attribute them to microscopic disorder and use a
phenomenological three-resistor model to account for their various features.
Our results showcase a new contribution of microscopic disorder in the
occurrence of novel phenomena. They may stimulate further work on tuning
electronic properties via disorder/defect nano-engineering
Additive manufacturing of solid diffractive optical elements via near index matching
Diffractive optical elements (DOEs) have a wide range of applications in
optics and photonics, thanks to their capability to perform complex wavefront
shaping in a compact form. However, widespread applicability of DOEs is still
limited, because existing fabrication methods are cumbersome and expensive.
Here, we present a simple and cost-effective fabrication approach for solid,
high-performance DOEs. The method is based on conjugating two nearly refractive
index-matched solidifiable transparent materials. The index matching allows for
extreme scaling up of the elements in the axial dimension, which enables simple
fabrication of a template using commercially available 3D printing at
tens-of-micrometer resolution. We demonstrated the approach by fabricating and
using DOEs serving as microlens arrays, vortex plates, including for highly
sensitive applications such as vector beam generation and super-resolution
microscopy using MINSTED, and phase-masks for three-dimensional single-molecule
localization microscopy. Beyond the advantage of making DOEs widely accessible
by drastically simplifying their production, the method also overcomes
difficulties faced by existing methods in fabricating highly complex elements,
such as high-order vortex plates, and spectrum-encoding phase masks for
microscopy
The Regulatory Effects of Paeoniflorin and Its Derivative Paeoniflorin-6′-O-Benzene Sulfonate CP-25 on Inflammation and Immune Diseases
The plant extract “total glucosides of peony” (TGP) constitutes a mixture of glycosides that is isolated from the roots of the well-known traditional Chinese herb Paeonia lactiflora Pall. Paeoniflorin (Pae) is the most abundant component and the main biologically active ingredient of TGP. Pharmacologically, Pae exhibits powerful anti-inflammatory and immune regulatory effects in some animal models of autoimmune diseases including Rheumatoid Arthritis (RA) and Systemic Lupus Erythematosus (SLE). Recently, we modified Pae with an addition of benzene sulfonate to achieve better bioavailability and higher anti-inflammatory immune regulatory effects. This review summarizes the pharmacological activities of Pae and the novel anti-inflammatory and immunomodulatory agent Paeoniflorin-6′-O-benzenesulfonate (CP-25) in various chronic inflammatory and autoimmune disorders. The regulatory effects of Pae and CP-25 make them promising agents for other related diseases, which require extensive investigation in the future
The lower bounds for the rank of matrices and some sufficient conditions for nonsingular matrices
Abstract The paper mainly discusses the lower bounds for the rank of matrices and sufficient conditions for nonsingular matrices. We first present a new estimation for ∑ i = 1 n | λ i | 2 ( λ i is an eigenvalue of a matrix) by using the partitioned matrices. By using this estimation and inequality theory, the new and more accurate estimations for the lower bounds for the rank are deduced. Furthermore, based on the estimation for the rank, some sufficient conditions for nonsingular matrices are obtained
Comparison of DNA vaccines with AS03 as an adjuvant and an mRNA vaccine against SARS-CoV-2
Summary: Emerging variants of SARS-CoV-2 call for frequent changes in vaccine antigens. Nucleic acid-based vaccination strategies are superior as the coding sequences can be easily altered with little impact on downstream production. mRNA vaccines, including variant-specific boosters, are approved for SARS-CoV-2. Here, we tested the efficacy of DNA vaccines against the SARS-CoV-2 Spike aided by the AS03 adjuvant using electroporation and compared their immunogenicity with an approved mRNA vaccine (mRNA-1273). DNA vaccination elicited robust humoral and cellular immune responses in C57BL/6 mice with Spike-specific antibody neutralization and T cells produced from 20 μg DNA vaccines similar to that from 0.5 μg mRNA-1273. Furthermore, a Nanoplasmid-based vector further increased the immunogenicity. Our results indicate that adjuvants are critical to the efficacy of DNA vaccines in stimulating robust immune responses against Spike, highlighting the feasibility of plasmid DNA as a rapid nucleic acid-based vaccine approach against SARS-CoV-2 and other emerging infectious diseases
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