668 research outputs found
Modulatory Function of Invariant Natural Killer T Cells in Systemic Lupus Erythematosus
Systemic lupus erythematosus (SLE) is a chronic autoimmune inflammatory disease with complex immunological and clinical manifestations. Multiple organ failure in SLE can be caused by immune dysfunction and deposition of autoantibodies. Studies of SLE-susceptible loci and the cellular and humoral immune responses reveal variable aberrations associated with this systemic disease. Invariant natural killer T (iNKT) cells are a unique subset of lymphocytes that control peripheral tolerance. Mounting evidence showing reductions in the proportion and activity of iNKT cells in SLE patients suggests the suppressive role of iNKT cells. Studies using murine lupus models demonstrate that iNKT cells participate in SLE progression by sensing apoptotic cells, regulating immunoglobulin production, and altering the cytokine profile upon activation. However, the dichotomy of iNKT cell actions in murine models implies complicated interactions within the body's milieu. Therefore, application of potential therapy for SLE using glycolipids to regulate iNKT cells should be undertaken cautiously
Bridge scour evaluation based on ambient vibration
The vulnerability of bridges to hazards such as earthquakes, wind and floods necessitates special structural characteristics. To guarantee the stability of bridge structures, the precise evaluation of the scour depth of bridge foundation has recently become an important issue, as most of the unexpected damage to or collapse of bridges has been attributed to hydraulic issues. In this paper, a vibration-based bridge health monitoring system that utilizes only the response of superstructure to rapidly evaluate the embedded depth of a bridge column is proposed. To clarify the complex fluid-solid coupling phenomenon, the effects of embedded depth and water level were first verified through a series of static experiments. A confined finite element model simulated by soil spring effects was then established to illustrate the relationship between the fundamental frequency and the embedded depth. Using the proposed algorithm, the health of the bridge is able to be inferred by processing the ambient vibration response of the superstructure. To implement the proposed algorithm, a SHM prototype system monitoring environmental factors such as temperature, water level, and inclination was developed to support on-line processing. The performance of the proposed system was verified by a series of dynamic bridge scour experiments conducted in a laboratory flume and compared with readings from a water-proof camera. The results showed that using the proposed vibration-based bridge health monitoring system, the embedded depth of bridge column during complex scour processes is able to be reliably calculated
Interrogating the superconductor Ca10(Pt4As8)(Fe2-xPtxAs2)5 Layer-by-layer
Ever since the discovery of high-Tc superconductivity in layered cuprates,
the roles that individual layers play have been debated, due to difficulty in
layer-by-layer characterization. While there is similar challenge in many
Fe-based layered superconductors, the newly-discovered Ca10(Pt4As8)(Fe2As2)5
provides opportunities to explore superconductivity layer by layer, because it
contains both superconducting building blocks (Fe2As2 layers) and intermediate
Pt4As8 layers. Cleaving a single crystal under ultra-high vacuum results in
multiple terminations: an ordered Pt4As8 layer, two reconstructed Ca layers on
the top of a Pt4As8 layer, and disordered Ca layer on the top of Fe2As2 layer.
The electronic properties of individual layers are studied using scanning
tunneling microscopy/spectroscopy (STM/S), which reveals different spectra for
each surface. Remarkably superconducting coherence peaks are seen only on the
ordered Ca/Pt4As8 layer. Our results indicate that an ordered structure with
proper charge balance is required in order to preserve superconductivity
Tailoring excitonic states of van der Waals bilayers through stacking configuration, band alignment and valley-spin
Excitons in monolayer semiconductors have large optical transition dipole for
strong coupling with light field. Interlayer excitons in heterobilayers, with
layer separation of electron and hole components, feature large electric dipole
that enables strong coupling with electric field and exciton-exciton
interaction, at the cost that the optical dipole is substantially quenched (by
several orders of magnitude). In this letter, we demonstrate the ability to
create a new class of excitons in transition metal dichalcogenide (TMD) hetero-
and homo-bilayers that combines the advantages of monolayer- and
interlayer-excitons, i.e. featuring both large optical dipole and large
electric dipole. These excitons consist of an electron that is well confined in
an individual layer, and a hole that is well extended in both layers, realized
here through the carrier-species specific layer-hybridization controlled
through the interplay of rotational, translational, band offset, and
valley-spin degrees of freedom. We observe different species of such
layer-hybridized valley excitons in different heterobilayer and homobilayer
systems, which can be utilized for realizing strongly interacting
excitonic/polaritonic gases, as well as optical quantum coherent controls of
bidirectional interlayer carrier transfer either with upper conversion or down
conversion in energy
Current Status of the Immunomodulation and Immunomediated Therapeutic Strategies for Multiple Sclerosis
Multiple sclerosis (MS) is an autoimmune disease of the central nervous system, and CD4+ T cells form the core immunopathogenic cascade leading to chronic inflammation. Traditionally, Th1 cells (interferon-γ-producing CD4+ T cells) driven by interleukin 12 (IL12) were considered to be the encephalitogenic T cells in MS and experimental autoimmune encephalomyelitis (EAE), an animal model of MS. Currently, Th17 cells (Il17-producing CD4+ T cells) are considered to play a fundamental role in the immunopathogenesis of EAE. This paper highlights the growing evidence that Th17 cells play the core role in the complex adaptive immunity of EAE/MS and discusses the roles of the associated immune cells and cytokines. These constitute the modern immunological basis for the development of novel clinical and preclinical immunomodulatory therapies for MS discussed in this paper
Visualizing Band Offsets and Edge States in Bilayer-Monolayer Transition Metal Dichalcogenides Lateral Heterojunction
Semiconductor heterostructures are fundamental building blocks for many
important device applications. The emergence of two-dimensional semiconductors
opens up a new realm for creating heterostructures. As the bandgaps of
transition metal dichalcogenides thin films have sensitive layer dependence, it
is natural to create lateral heterojunctions using the same materials with
different thicknesses. Using scanning tunneling microscopy and spectroscopy,
here we show the real space image of electronic structures across the
bilayer-monolayer interface in MoSe2 and WSe2. Most bilayer-monolayer
heterojunctions are found to have a zigzag-orientated interface, and the band
alignment of such atomically sharp heterojunctions is of type-I with a
well-defined interface mode which acts as a narrower-gap quantum wire. The
ability to utilize such commonly existing thickness terrace as lateral
heterojunctions is a crucial addition to the tool set for device applications
based on atomically thin transition metal dichalcogenides, with the advantage
of easy and flexible implementation.Comment: 19 pages in total, 4 figures and 1 tabl
Tailoring Plasmonic Enhanced Upconversion in Single NaYF4:Yb3+/Er3+ Nanocrystals
By using silver nanoplatelets with a widely tunable localized surface plasmon resonance (LSPR) and their corresponding local field enhancement, here we show large manipulation of plasmonic enhanced upconversion in NaYF4:Yb3+/Er3+ nanocrystals at the single particle level. In particular, we show that when the plasmonic resonance of silver nanolplatelets is tuned to 656 nm, matching the emission wavelength, an upconversion enhancement factor ~5 is obtained. However, when the plasmonic resonance is tuned to 980 nm, matching the nanocrystal absorption wavelength, we achieve an enhancement factor of ~22 folds. The precise geometric arrangement between fluorescent nanoparticles and silver nanoplatelets allows us to make, for the first time, a comparative analysis between experimental results and numerical simulations, yielding a quantitative agreement at the single particle level. Such a comparison lays the foundations for a rational design of hybrid metal-fluorescent nanocrystals to harness the upconversion enhancement for biosensing and light harvesting applications
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