3,094 research outputs found
Electronic Structures of Graphene Layers on Metal Foil: Effect of Point Defects
Here we report a facile method to generate a high density of point defects in
graphene on metal foil and show how the point defects affect the electronic
structures of graphene layers. Our scanning tunneling microscopy (STM)
measurements, complemented by first principle calculations, reveal that the
point defects result in both the intervalley and intravalley scattering of
graphene. The Fermi velocity is reduced in the vicinity area of the defect due
to the enhanced scattering. Additionally, our analysis further points out that
periodic point defects can tailor the electronic properties of graphene by
introducing a significant bandgap, which opens an avenue towards all-graphene
electronics.Comment: 4 figure
Study on electromagnetically induced transparency effects in Dirac and VO hybrid material structure
In this paper, we present a metamaterial structure of Dirac and vanadium
dioxide and investigate its optical properties using the finite-difference
time-domain (FDTD) technique. Using the phase transition feature of vanadium
dioxide, the design can realize active tuning of the PIT effect at terahertz
frequency, thereby converting from a single PIT to a double PIT. When VO is
in the insulating state, the structure is symmetric to obtain a single-band PIT
effect; When VO is in the metallic state, the structure turns asymmetric to
realize a dual-band PIT effect. This design provides a reference direction for
the design of actively tunable metamaterials. Additionally, it is discovered
that the transparent window's resonant frequency and the Dirac material's Fermi
level in this structure have a somewhat linear relationship. In addition, the
structure achieves superior refractive index sensitivity in the terahertz band,
surpassing 1 THz/RIU. Consequently, the concept exhibits encouraging potential
for application in refractive index sensors and optical switches
Design and Testing of an Online Fertilizing Amount Detection Device Based on the Moment Balance Principle
Based on the principle of moment balance, this paper designs a fertilizer application amount online detection device, which is mainly composed of two major parts: the fertilizer guide mechanism and the fertilizer metering and discharging mechanism.Under the electromagnetic reversing and buffering of the fertilizer guide mechanism, the fertilizer discharged into the device falls alternately into the storage box of the two metering units of the metering and discharging mechanism. Once the gravity of the fertilizer in the storage box is greater than the suction of the electromagnetic sucker, the fertilizer discharging board is automatically opened for fertilizer discharge, and the metering pulse signal is accumulated once. Meanwhile, the fertilizer guide plate is driven by the electromagnetic commutator to reverse the material, and then another storage box is started for fertilizer storage and metering. In this approach, online detection of fertilizer flow can be realized by repeatedly guiding and reversing and metering the incoming fertilizer. According to the single metering fertilizer quality and the number of metering pulse signals, the fertilization amount can be calculated in real-time.The performance of the device was verified by bench test. The test results indicated that: The established fertilizer application detection model is a quadratic function (R2>0.98), and the verification error was less than 3.73% in the detection of alternating cycle fertilizer discharge; the coefficient of determination (R2) and the root mean square error (RMSE) reached 0.992 and 9.858 respectively, indicating high detection accuracy of the device is
microRNA-33a-5p increases radiosensitivity by inhibiting glycolysis in melanoma.
Glycolysis was reported to have a positive correlation with radioresistance. Our previous study found that the miR-33a functioned as a tumor suppressor in malignant melanoma by targeting hypoxia-inducible factor1-alpha (HIF-1α), a gene known to promote glycolysis. However, the role of miR-33a-5p in radiosensitivity remains to be elucidated. We found that miR-33a-5p was downregulated in melanoma tissues and cells. Cell proliferation was downregulated after overexpression of miR-33a-5p in WM451 cells, accompanied by a decreased level of glycolysis. In contrast, cell proliferation was upregulated after inhibition of miR-33a-5p in WM35 cells, accompanied by increased glycolysis. Overexpression of miR-33a-5p enhanced the sensitivity of melanoma cells to X-radiation by MTT assay, while downregulation of miR-33a-5p had the opposite effects. Finally, in vivo experiments with xenografts in nude mice confirmed that high expression of miR-33a-5p in tumor cells increased radiosensitivity via inhibiting glycolysis. In conclusions, miR-33a-5p promotes radiosensitivity by negatively regulating glycolysis in melanoma
DisCo: Remedy Self-supervised Learning on Lightweight Models with Distilled Contrastive Learning
While self-supervised representation learning (SSL) has received widespread
attention from the community, recent research argue that its performance will
suffer a cliff fall when the model size decreases. The current method mainly
relies on contrastive learning to train the network and in this work, we
propose a simple yet effective Distilled Contrastive Learning (DisCo) to ease
the issue by a large margin. Specifically, we find the final embedding obtained
by the mainstream SSL methods contains the most fruitful information, and
propose to distill the final embedding to maximally transmit a teacher's
knowledge to a lightweight model by constraining the last embedding of the
student to be consistent with that of the teacher. In addition, in the
experiment, we find that there exists a phenomenon termed Distilling BottleNeck
and present to enlarge the embedding dimension to alleviate this problem. Our
method does not introduce any extra parameter to lightweight models during
deployment. Experimental results demonstrate that our method achieves the
state-of-the-art on all lightweight models. Particularly, when
ResNet-101/ResNet-50 is used as teacher to teach EfficientNet-B0, the linear
result of EfficientNet-B0 on ImageNet is very close to ResNet-101/ResNet-50,
but the number of parameters of EfficientNet-B0 is only 9.4\%/16.3\% of
ResNet-101/ResNet-50. Code is available at https://github.
com/Yuting-Gao/DisCo-pytorch.Comment: ECCV 202
Power-Law Decay of Standing Waves on the Surface of Topological Insulators
We propose a general theory on the standing waves (quasiparticle interference
pattern) caused by the scattering of surface states off step edges in
topological insulators, in which the extremal points on the constant energy
contour of surface band play the dominant role. Experimentally we image the
interference patterns on both BiTe and BiSe films by measuring
the local density of states using a scanning tunneling microscope. The observed
decay indices of the standing waves agree excellently with the theoretical
prediction: In BiSe, only a single decay index of -3/2 exists; while in
BiTe with strongly warped surface band, it varies from -3/2 to -1/2 and
finally to -1 as the energy increases. The -1/2 decay indicates that the
suppression of backscattering due to time-reversal symmetry does not
necessarily lead to a spatial decay rate faster than that in the conventional
two-dimensional electron system. Our formalism can also explain the
characteristic scattering wave vectors of the standing wave caused by
non-magnetic impurities on BiTe.Comment: 4 pages, 3 figure
Bank Credit Strategy Model Based on AHP-Fuzzy Comprehensive Evaluation
Credit risk control and credit strategy formulation of medium and micro enterprises have always been important strategic issues faced by commercial banks. Banks usually make corporate loan policies based on the credit degree, the information of trading bills and the relationship of supply-demand chain of the enterprise. In this paper, we established the AHP-Fuzzy comprehensive evaluation model for quantifying enterprise credit risk. Based on the relevant data of 123 enterprises with credit records, the credit strategy is formulated according to the three indicators of enterprise strength, enterprise reputation and stability of supply-demand relationship. This paper also combines the credit reputation, credit risk and supply and demand stability rating in order to establish the bank credit strategic planning model to decide whether to lend or not and the lending order. The conclusion shows that, under the condition of constant total loan amount, the enterprises with the highest credit rating should be given priority. Then, combined with the change of customer turnover rate with interest rate, we take the bank's maximize expected income as objective to calculate the optimal loan interest rate of different customer groups
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