386 research outputs found
Spin fluctuations and charge properties of core shell C+M (V, Mn, Cr, Ni, Co)
Transition metal clusters have a broad spectrum of potential applications in
electronic and magnetic devices owing to their unique properties. Protective
shells such as fullerene C can be introduced to improve their stability.
In this study, we optimized five core shell structures, C+M (V,
Mn, Cr, Ni, Co), and calculated their electromagnetic properties using density
functional theory.We determined that there is electron transfer between
C and the transition metal clusters near the Fermi surface, and that the
d orbitals contribute most to the magnetism of the structure.
C+Ni was antiferromagnetic. The magnetic properties of the
clusters were significantly altered, revealing antiferromagnetism. The results
establish a theoretical starting point for tuning the electronic and magnetic
properties of 13-atom clusters embedded in fullerene cages
Effects of Rain Events on Carbon Fluxes from Biological Soil Crusts
In dry ecosystems, biological soil crusts (BSCs) have been suggested as one of the factors responsible for the large rate of annual CO2 net uptake (Xie et al. 2009). However, most studies carried out on carbon (C) fluxes in arid and semi-arid ecosystems, such as soil respiration, have neglected the carbon fluxes from BSCs. Although BSCs are a vital component of the dry-land soil C cycle, few studies have parameterized the conditions required for photosynthesis in BSCs or determined BSCs respiration (Elbert et al. 2009, Castillo-Monroy et al. 2011). Precipitation in dry land is dominated by small events (Lauenroth and Bradford 2009). Even the smallest events will influence the carbon fluxes of BSCs, while intermediate pulses might wet the subsurface biotic community, and typically only larger events are used by plants for carbon gain or growth of roots or shoots (Belnap et al. 2005). As BSCs dry quickly and are hence very responsive to moisture pulses, the pulsed nature of precipitation can lead to highly variable carbon fluxes from BSCs (Bowling et al. 2011). Therefore, it is very important to study the effect of rain events upon carbon fluxes through BSCs in the dry ecosystem
Carbon Sequestration in Relation to Shrub Size in the Desert Ecosystem
Desert ecosystems have been reported as the location of the long-sought ‘missing sink’ for atmospheric carbon dioxide and as a potentially important area for carbon sequestering from fossil fuel combustion in the future (Stone 2008). Researchers have found that net uptake of carbon in the Mojave Desert ranged from 102 to 127 g C m2/yr during a 3-year period, which is equivalent to the net ecosystem production of many forest ecosystems with a much higher biomass (Luyssaert et al. 2007; Wohlfahrt et al. 2008). Shrub is the dominant plant of desert ecosystems (Gratani et al. 2011); hence, it is important to understand the dynamics of carbon sequestration by shrubs as well as their role in desert ecosystem carbon balance. Information on the carbon sequestration associated with shrub size is limited. Our objective was, therefore, to find out the relationship between carbon sequestration potential and size of shrubs
Experimental Demonstration of High-Dimensional Quantum Steering With Measurement Settings
High-dimensional (HD) quantum systems possess advantages of larger channel
capacity, stronger noise resilience and higher security against attacks in
quantum communication compared with qubit systems. Here, we experimentally
demonstrate HD quantum steering criterion with measurement settings in
high-noise environments. We verify the unbounded violation of steering
equalities, revealing a high strength of steering without full-state
tomography. Moreover, our results exhibit that the noise resilience can be
enhanced with both extra dimension and measurement settings. We experimentally
certify 11-dimensional steering with 60.5% isotropic noise, exceeding the upper
bound of 2-setting steering criteria. Our work paves the way for the
certification of HD quantum correlations with high noise in quantum information
processing
Insights into innate immune cell evasion by Chlamydia trachomatis
Chlamydia trachomatis, is a kind of obligate intracellular pathogen. The removal of C. trachomatis relies primarily on specific cellular immunity. It is currently considered that CD4+ Th1 cytokine responses are the major protective immunity against C. trachomatis infection and reinfection rather than CD8+ T cells. The non-specific immunity (innate immunity) also plays an important role in the infection process. To survive inside the cells, the first process that C. trachomatis faces is the innate immune response. As the “sentry” of the body, mast cells attempt to engulf and remove C. trachomatis. Dendritic cells present antigen of C. trachomatis to the “commanders” (T cells) through MHC-I and MHC-II. IFN-γ produced by activated T cells and natural killer cells (NK) further activates macrophages. They form the body’s “combat troops” and produce immunity against C. trachomatis in the tissues and blood. In addition, the role of eosinophils, basophils, innate lymphoid cells (ILCs), natural killer T (NKT) cells, γδT cells and B-1 cells should not be underestimated in the infection of C. trachomatis. The protective role of innate immunity is insufficient, and sexually transmitted diseases (STDs) caused by C. trachomatis infections tend to be insidious and recalcitrant. As a consequence, C. trachomatis has developed a unique evasion mechanism that triggers inflammatory immunopathology and acts as a bridge to protective to pathological adaptive immunity. This review focuses on the recent advances in how C. trachomatis evades various innate immune cells, which contributes to vaccine development and our understanding of the pathophysiologic consequences of C. trachomatis infection
Variation of polarization distribution of reflected beam caused by spin separation
The variation of polarization distribution of reflected beam at specular
interface and far field caused by spin separation has been studied. Due to the
diffraction effect, we find a distinct difference of light polarization at the
two regions. The variation of polarization distribution of reflected light
provides a new method to measure the spin separation displacement caused by
Spin Hall Effect of light.Comment: 7 pages, 5 figure
Spin polarization separation of reflected light at Brewster angle
A novel spin polarization separation of reflected light is observed, when a
linearly polarized Gaussian beam impinges on an air-glass interface at Brewster
angle. In the far-field zone, spins of photons are oppositely polarized in two
regions along the direction perpendicular to incident plane. Spatial scale of
this polarization is related to optical properties of dielectric and can be
controlled by experimental configuration. We believe that this study benefits
the manipulation of spins of photons and the development of methods for
investigating optical properties of materials.Comment: 4 pages, 2 figure
Tongxinluo Regulates Expression of Tight Junction Proteins and Alleviates Endothelial Cell Monolayer Hyperpermeability via ERK-1/2 Signaling Pathway in Oxidized Low-Density Lipoprotein-Induced Human Umbilical Vein Endothelial Cells
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Modeling Study of the Air Quality Impact of Record-Breaking Southern California Wildfires in December 2017
We investigate the air quality impact of record‐breaking wildfires in Southern California during 5–18 December 2017 using the Weather Research and Forecasting model with Chemistry in combination with satellite and surface observations. This wildfire event was driven by dry and strong offshore Santa Ana winds, which played a critical role in fire formation and air pollutant transport. By utilizing fire emissions derived from the high‐resolution (375 × 375 m²) Visible Infrared Imaging Radiometer Suite active fire detections, the simulated magnitude and temporal evolution of fine particulate matter (PM_(2.5)) concentrations agree reasonably well with surface observations (normalized mean bias = 4.0%). Meanwhile, the model could generally capture the spatial pattern of aerosol optical depth from satellite observations. Sensitivity tests reveal that using a high spatial resolution for fire emissions and a reasonable treatment of plume rise (a fair split between emissions injected at surface and those lifted to upper levels) is important for achieving decent PM_(2.5) simulation results. Biases in PM_(2.5) simulation are relatively large (about 50%) during the period with the strongest Santa Ana wind, due to a possible underestimation of burning area and uncertainty in wind field variation. The 2017 December fire event increases the 14‐day averaged PM_(2.5) concentrations by up to 231.2 μg/m³ over the downwind regions, which substantially exceeds the U.S. air quality standards, potentially leading to adverse health impacts. The human exposure to fire‐induced PM_(2.5) accounts for 14–42% of the annual total PM_(2.5) exposure in areas impacted by the fire plumes
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