6,586 research outputs found
Modeling the underlying mechanisms for organic memory devices: Tunneling, electron emission and oxygen adsorbing
We present a combined experimental and theoretical study to get insight into
both memory and negative differential resistance (NDR) effect in organic memory
devices. The theoretical model we propose is simply a one-dimensional metallic
island array embedding within two electrodes. We use scattering operator method
to evaluate the tunneling current among the electrode and islands to establish
the basic bistable I-V curves for several devices. The theoretical results
match the experiments very well, and both memory and NDR effect could be
understood comprehensively. The experimental correspondence, say, the
experiment of changing the pressure of oxygen, is addressed as well.Comment: 5 pages, 3 figure
THz Nanoscopy of Metal and Gallium Implanted Silicon
Drude model successfully quantifies the optical constants for bulk matter,
but it is not suitable for subwavelength objects. In this paper, terahertz
near-field optical microscopy and finite element simulation are used to study
gold patches fabricated by Gallium etching. Electron transport is discovered in
determining the optical signal strength. The signal from substrate is more
complicated and still not fully understood. As the etching area decreases,
near-field interaction is not dominated by doping concentration, and a higher
signal is observed near connected metals. With the help of simulation, the
abnormal enhancement phenomenon is discussed in detail, which lays the
foundation for further experimental verification
A Leaf Recognition Algorithm for Plant Classification Using Probabilistic Neural Network
In this paper, we employ Probabilistic Neural Network (PNN) with image and
data processing techniques to implement a general purpose automated leaf
recognition algorithm. 12 leaf features are extracted and orthogonalized into 5
principal variables which consist the input vector of the PNN. The PNN is
trained by 1800 leaves to classify 32 kinds of plants with an accuracy greater
than 90%. Compared with other approaches, our algorithm is an accurate
artificial intelligence approach which is fast in execution and easy in
implementation.Comment: 6 pages, 3 figures, 2 table
Extraction of Uranium from Seawater: Design and Testing of a Symbiotic System
Uranium present in low concentration in ocean water has the potential to greatly augment the current fuel reserve for nuclear power generation, but the challenge of extracting it economically remains. Two new designs of seawater uranium extraction systems are proposed in this paper—a stationary system and a continuous system—both of which utilize a braided polymer adsorbent. The stationary system simplifies the recovery procedure, and it is predicted to produce uranium at 403/kg of uranium.MIT Energy InitiativeS. D. Bechtel, Jr. Foundatio
Influence of electrode thermal conductivity on resistive switching behavior during reset process
Resistive random access memory (RRAM) is the most promising candidate for non-volatile memory (NVM) due to its extremely low operation voltage, extremely fast write/erase speed, and excellent scaling capability. However, an obstacle hindering mass production of RRAM is the non-uniform physical mechanism in its resistance switching process. This study examines the influence of different electrode thermal conductivity on switching behavior during the reset process. Electrical analysis methods and an analysis of current conduction mechanism indicate that better thermal conductivity in the electrode will require larger input power in order to induce more active oxygen ions to take part in the reset process. More active oxygen ions cause a more complete reaction during the reset process, and cause the effective switching gap (dsw) to become thicker. The effect of the electrode thermal conductivity and input power are explained by our model and clarified by electrical analysis methods.
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Simplified ZrTiOx-based RRAM cell structure with rectifying characteristics by integrating Ni/n + -Si diode
A simplified one-diode one-resistor (1D1R) resistive switching memory cell that uses only four layers of TaN/ZrTiO( x )/Ni/n(+)-Si was proposed to suppress sneak current where TaN/ZrTiO( x )/Ni can be regarded as a resistive-switching random access memory (RRAM) device while Ni/n(+)-Si acts as an Schottky diode. This is the first RRAM cell structure that employs metal/semiconductor Schottky diode for current rectifying. The 1D1R cell exhibits bipolar switching behavior with SET/RESET voltage close to 1 V without requiring a forming process. More importantly, the cell shows tight resistance distribution for different states, significantly rectifying characteristics with forward/reverse current ratio higher than 10(3) and a resistance ratio larger than 10(3) between two states. Furthermore, the cell also displays desirable reliability performance in terms of long data retention time of up to 10(4) s and robust endurance of 10(5) cycles. Based on the promising characteristics, the four-layer 1D1R structure holds the great potential for next-generation nonvolatile memory technology
Lasing on nonlinear localized waves in curved geometry
The use of geometrical constraints opens many new perspectives in photonics
and in fundamental studies of nonlinear waves. By implementing surface
structures in vertical cavity surface emitting lasers as manifolds for curved
space, we experimentally study the impacts of geometrical constraints on
nonlinear wave localization. We observe localized waves pinned to the maximal
curvature in an elliptical-ring, and confirm the reduction in the localization
length of waves by measuring near and far field patterns, as well as the
corresponding dispersion relation. Theoretically, analyses based on a
dissipative model with a parabola curve give good agreement remarkably to
experimental measurement on the transition from delocalized to localized waves.
The introduction of curved geometry allows to control and design lasing modes
in the nonlinear regime.Comment: 6 pages, 6 figure
Rottlerin Inhibits Lonicera japonica-Induced Photokilling in Human Lung Cancer Cells through Cytoskeleton-Related Signaling Cascade
This study demonstrated that many apoptotic signaling pathways, such as Rho family, PKC family, MAP kinase family, and mitochondria-mediated apoptotic pathway, were triggered by Lonicera japonica extracts and irradiation in CH27 cells. Rottlerin, a PKCδ
-selective inhibitor, reversed the photoactivated Lonicera japonica extract-induced decrease in PKCδ protein expression and change in cell morphology in this study. In addition, rottlerin inhibited the photoactivated Lonicera japonica-induced decrease in protein expression of Ras, ERK, p38, PKCα, and PKCε, which are the kinases of prosurvival signaling pathway. We also demonstrated that pretreatment with rottlerin prevented actin microfilaments and microtubules from damage during the photoactivated Lonicera japonica-induced CH27 cell death. Furthermore, the promotion of the cytoskeleton-related signaling cascade following rottlerin by upregulation of cytoskeleton-related mediators (p38, HSP27, FAK, paxillin, and tubulin) and molecules of downstream of F-actin (mitochondria-mediated apoptosis pathway) reduces CH27 cell death, indicating that cytoskeleton is the potential target in the photoactivated Lonicera japonicaextract-induced photokilling of CH27 cells
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