3,832 research outputs found
Graphene-based spintronic components
A major challenge of spintronics is in generating, controlling and detecting
spin-polarized current. Manipulation of spin-polarized current, in particular,
is difficult. We demonstrate here, based on calculated transport properties of
graphene nanoribbons, that nearly +-100% spin-polarized current can be
generated in zigzag graphene nanoribbons (ZGNRs) and tuned by a source-drain
voltage in the bipolar spin diode, in addition to magnetic configurations of
the electrodes. This unusual transport property is attributed to the intrinsic
transmission selection rule of the spin subbands near the Fermi level in ZGNRs.
The simultaneous control of spin current by the bias voltage and the magnetic
configurations of the electrodes provides an opportunity to implement a whole
range of spintronics devices. We propose theoretical designs for a complete set
of basic spintronic devices, including bipolar spin diode, transistor and logic
gates, based on ZGNRs.Comment: 14 pages, 4 figure
Full-range Gate-controlled Terahertz Phase Modulations with Graphene Metasurfaces
Local phase control of electromagnetic wave, the basis of a diverse set of
applications such as hologram imaging, polarization and wave-front
manipulation, is of fundamental importance in photonic research. However, the
bulky, passive phase modulators currently available remain a hurdle for
photonic integration. Here we demonstrate full-range active phase modulations
in the Tera-Hertz (THz) regime, realized by gate-tuned ultra-thin reflective
metasurfaces based on graphene. A one-port resonator model, backed by our
full-wave simulations, reveals the underlying mechanism of our extreme phase
modulations, and points to general strategies for the design of tunable
photonic devices. As a particular example, we demonstrate a gate-tunable THz
polarization modulator based on our graphene metasurface. Our findings pave the
road towards exciting photonic applications based on active phase
manipulations
Interleukin-11 Promotes the Progress of Gastric Carcinoma via Abnormally Expressed Versican
Versican, a ubiquitous component of the extracellular matrix (ECM), accumulates both in tumor stroma and cancer cells and is highly regulated by various cytokines. The aberrant expression of versican and its isoforms is known to modulate cell proliferation, differentiation, and migration, all of which are features of the invasion and metastasis of cancer; versican is also known to favour the homeostasis of the ECM. Interleukin-11 (IL-11) is an important cytokine that exhibits a wide variety of biological effects in gastric cancer development. Here, we analysed the expression of versican isoforms and found that the major isoforms expressed by both gastric carcinoma tissue and gastric cell lines were V0 and V1, and V1 was significantly higher in gastric carcinoma tissue. The treatment of the gastric cell lines AGS and MKN45 with rhIL-11 resulted in a significant increase in the expression of V0 and V1. Exogenous IL-11 increased migration in AGS and MKN45 cells, whereas these effects were reversed when the expression of V0 and V1 were abolished by siRNA targeting versican V0/V1. Collectively, these findings suggest that the abnormally expressed versican and its isoforms participate, at least in part, in the progress of gastric carcinoma triggered by IL-11
Flux density measurements for 32 pulsars in the 20 cm band
Flux density measurements provide fundamental observational parameters that
describe a pulsar. In the current pulsar catalogue, 27% of radio pulsars have
no flux density measurement in the 20 cm observing band. Here, we present the
first measurements of the flux densities in this band for 32 pulsars observed
using the Parkes radio telescope and provide updated pulse profiles for these
pulsars. We have used both archival and new observations to make these
measurements. Various schemes exist for measuring flux densities. We show how
the flux densities measured vary between these methods and how the presence of
radio-frequency-interference will bias flux density measurementsComment: Accepted by RA
Phylogenetic structure and formation mechanism of shrub communities in arid and semiarid areas of the Mongolian Plateau
The mechanisms of species coexistence within a community have always been the focus in ecological research. Community phylogenetic structure reflects the relationship of historical processes, regional environments, and interactions between species, and studying it is imperative to understand the formation and maintenance mechanisms of community composition and biodiversity. We studied the phylogenetic structure of the shrub communities in arid and semiarid areas of the Mongolian Plateau. First, the phylogenetic signals of four plant traits (height, canopy, leaf length, and leaf width) of shrubs and subshrubs were measured to determine the phylogenetic conservation of these traits. Then, the net relatedness index (NRI) of shrub communities was calculated to characterize their phylogenetic structure. Finally, the relationship between the NRI and current climate and paleoclimate (since the Last Glacial Maximum, LGM) factors was analyzed to understand the formation and maintenance mechanisms of these plant communities. We found that desert shrub communities showed a trend toward phylogenetic overdispersion; that is, limiting similarity was predominant in arid and semiarid areas of the Mongolian Plateau despite the phylogenetic structure and formation mechanisms differing across habitats. The typical desert and sandy shrub communities showed a significant phylogenetic overdispersion, while the steppified desert shrub communities showed a weak phylogenetic clustering. It was found that mean winter temperature (i.e., in the driest quarter) was the major factor limiting steppified desert shrub phylogeny distribution. Both cold and drought (despite having opposite consequences) differentiated the typical desert to steppified desert shrub communities. The increase in temperature since the LGM is conducive to the invasion of shrub plants into steppe grassland, and this process may be intensified by global warming
Inherent Safer Design for Chemical Process of 1,4-dioldiacetate-2-butene Oxidized by Ozone
PresentationOxidation reaction is the typical thermal runaway reaction. The reaction of 1,4-dioldiacetate-2- Butene oxidized by ozone was chosen to study the thermal hazards during the chemical process and the inherent safer designs (ISD) were proposed after analysis. The Qualitative Assessment for Inherently Safer Design (QAISD) was used to identify the risk during the chemical process. Meanwhile, the Reaction Calorimeter (RC1e) was used to analyze the thermal hazards of the chemical process. Two Inherent safer designs were proposed to increase the safe level of the process. ISD I is the improved reaction condition of reaction temperature at -5°C and ventilation rate of 200L•h-1, as well, ISDII is using a tubular reactor. The results indicate that the classification of the reaction hazard was lower with improvements of two ISDs, and the severity was reduced by 43%. Moreover, the inherent safety level of the reaction was increased by ISD I &IIof 63% and 43.4% respectively, which both have positive effects on inherent safety theories of "minimize", "substitute" and "moderate"
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