2,182 research outputs found
Terminal Sliding Mode Control of Mobile Wheeled Inverted Pendulum System with Nonlinear Disturbance Observer
A terminal sliding mode controller with nonlinear disturbance observer is investigated to control mobile wheeled inverted pendulum system. In order to eliminate the main drawback of the sliding mode control, “chattering” phenomenon, and for compensation of the model uncertainties and external disturbance, we designed a nonlinear disturbance observer of the mobile wheeled inverted pendulum system. Based on the nonlinear disturbance observer, a terminal sliding mode controller is also proposed. The stability of the closed-loop mobile wheeled inverted pendulum system is proved by Lyapunov theorem. Simulation results show that the terminal sliding mode controller with nonlinear disturbance observer can eliminate the “chattering” phenomenon, improve the control precision, and suppress the effects of external disturbance and model uncertainties effectively
Estrogen-Dependent Epigenetic Regulation of Soluble Epoxide Hydrolase via DNA Methylation
To elucidate molecular mechanisms responsible for the sexually dimorphic phenotype of soluble epoxide hydrolase (sEH) expression, we tested the hypothesis that female-specific down-regulation of sEH expression is driven by estrogen-dependent methylation of the Ephx2 gene. Mesenteric arteries isolated from male, female, ovariectomized female (OV), and OV with estrogen replacement (OVE) mice, as well as the human cell line (HEK293T) were used. Methylation-specific PCR and bisulfite genomic sequencing analysis indicate significant increases in DNA/CG methylation in vessels of female and OVE compared with those of male and OV mice. The same increase in CG methylation was also observed in male vessels incubated with a physiological concentration of 17beta-estradiol (17beta-E2) for 48 hours. All vessels that displayed increases in CG methylation were concomitantly associated with decreases in their Ephx2 mRNA and protein, suggesting a methylation-induced gene silencing. Transient transfection assays indicate that the activity of Ephx2 promoter-coding luciferase was significantly attenuated in HEK293T cells treated with 17beta-E2, which was prevented by additional treatment with an estrogen receptor antagonist (ICI). ChIP analysis indicates significantly reduced binding activities of transcription factors (including SP1, AP-1, and NF-kappaB with their binding elements located in the Ephx2 promoter) in vessels of female mice and human cells treated with 17beta-E2, responses that were prevented by ICI and Decitabine (DNA methyltransferase inhibitor), respectively. In conclusion, estrogen/estrogen receptor-dependent methylation of the promoter of Ephx2 gene silences sEH expression, which is involved in specific transcription factor-directed regulatory pathways
Isospin Effect on the Process of Multifragmentation and Dissipation at Intermediate Energy Heavy Ion Collisions
In the simulation of intermediate energy heavy ion collisions by using the
isospin dependent quantum molecular dynamics, the isospin effect on the process
of multifragmentation and dissipation has been studied. It is found that the
multiplicity of intermediate mass fragments for the neutron-poor
colliding system is always larger than that for the neutron-rich system, while
the quadrupole of single particle momentum distribution for the
neutron-poor colliding system is smaller than that of the neutron-rich system
for all projectile-target combinations studied at the beam energies from about
50MeV/nucleon to 150MeV/nucleon. Since depends strongly on isospin
dependence of in-medium nucleon-nucleon cross section and weakly on symmetry
potential at the above beam energies, it may serve as a good probe to extract
the information on the in-medium nucleon-nucleon cross section. The correlation
between the multiplicity of intermediate mass fragments and the total
numer of charged particles has the behavior similar to , which
can be used as a complementary probe to the in-medium nucleon-nucleon cross
section.Comment: 18 pages, 9 figure
SERS discrimination of single amino acid residue in single peptide by plasmonic nanocavities
Surface-enhanced Raman spectroscopy (SERS) is a sensitive label-free optical
method that can provide fingerprint Raman spectra of biomolecules such as DNA,
amino acids and proteins. While SERS of single DNA molecule has been recently
demonstrated, Raman analysis of single protein sequence was not possible
because the SERS spectra of proteins are usually dominated by signals of
aromatic amino acid residues. Here, we used electroplasmonic approach to trap
single gold nanoparticle in a nanohole for generating a plasmonic nanocavity
between the trapped nanoparticle and the nanopore wall. The giant field
generated in the nanocavity was so sensitive and localized that it enables SERS
discrimination of 10 distinct amino acids at single-molecule level. The
obtained spectra are used to analyze the spectra of 2 biomarkers (Vasopressin
and Oxytocin) made of a short sequence of 9 amino-acids. Significantly, we
demonstrated identification of single non-aromatic amino acid residues in a
single short peptide chain as well as discrimination between two peptides with
sequences distinguishable in 2 specific amino-acids. Our result demonstrate the
high sensitivity of our method to identify single amino acid residue in a
protein chain and a potential for further applications in proteomics and
single-protein sequencing.Comment: Totally 22 pages, 12 figures and 3 tables including supporting
information. arXiv admin note: text overlap with arXiv:1905.0185
SAPNet: a deep learning model for identification of single-molecule peptide post-translational modifications with surface enhanced Raman spectroscopy
Nanopore resistive pulse sensors are emerging technologies for
single-molecule protein sequencing. But they can hardly detect small
post-translational modifications (PTMs) such as hydroxylation in
single-molecule level. While a combination of surface enhanced Raman
spectroscopy (SERS) with plasmonic nanopores can detect the small PTMs, the
blinking Raman peaks in the single-molecule SERS spectra leads to a big
challenge in data analysis and PTM identification. Herein, we developed and
validated a one-dimensional convolutional neural network (1D-CNN) for amino
acids and peptides identification from their PTMs including hydroxylation and
phosphorylation by their single-molecule SERS spectra, named Single Amino acid
and Peptide Network (SAPNet). Our work combines cutting-edge plasmonic nanopore
technology for SERS signal acquisition and deep learning for fully automated
extraction of information from the SERS signals. The SAPNet model achieved an
overall accuracy of 99.66% for the identification of amino acids from their
modification, and 98.38% for the identification of peptides from their PTM
translation. We also evaluated the model with out-of-sample examples with good
performance. Our work can be beneficial for early detection of diseases such as
cancers and Alzheimer's disease.Comment: 20 pages, 5 figures, 2 table
Enhanced surface acceleration of fast electrons by using sub-wavelength grating targets
Surface acceleration of fast electrons in intense laser-plasma interaction is
improved by using sub-wavelength grating targets. The fast electron beam
emitted along the target surface was enhanced by more than three times relative
to that by using planar target. The total number of the fast electrons ejected
from the front side of target was also increased by about one time. The method
to enhance the surface acceleration of fast electron is effective for various
targets with sub-wavelength structured surface, and can be applied widely in
the cone-guided fast ignition, energetic ion acceleration, plasma device, and
other high energy density physics experiments.Comment: 14 pages, 4figure
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