77 research outputs found
On the Whitney disks in Heegaard Floer homology theory
The Whitney disks play a central role in defining Heegaard Floer homology of
a -dimensional manifold. We use Nielsen theory to a simple criterion to the
existence of Whitney disks, connecting two given intersections
Persistence of sub-chain groups
In this work, we present a generalization of extended persistent homology to
filtrations of graded sub-groups by defining relative homology in this setting.
Our work provides a more comprehensive and flexible approach to get an
algebraic invariant overcoming the limitations of the standard approach. The
main contribution of our work is the development of a stability theorem for
extended persistence modules using an extension of the definition of
interleaving and the rectangle measure. This stability theorem is a crucial
property for the application of mathematical tools in data analysis. We apply
the stability theorem to extended persistence modules obtained from extended
path homology of directed graphs and extended homology of hypergraphs, which
are two important examples in topological data analysis
Drive laser system for the DC-SRF photoinjector at Peking University
Photoinjectors are widely used for linear accelerators as electron sources to
generate high-brightness electron beam. Drive laser, which determines the
timing structure and quality of the electron beam, is a crucial device of
photoinjector. A new drive laser system has been designed and constructed for
the upgraded 3.5-cell DC-SRF photoinjector at Peking University. The drive
laser system consists of a 1064 nm laser oscillator, a four- stage amplifier,
the second and fourth harmonic generators, the optical system to transfer the
UV pulses to the photocathode, and the synchronization system. The drive laser
system has been successfully applied in the stable operation of DC-SRF
photoinjector and its performance meets the requirements. 266 nm laser with an
average power close to 1W can be delivered to illuminate the Cs2Te photocathode
and the instability is less than 5% for long time operation. The design
consideration for improving the UV laser quality, a detailed description of
laser system, and its performance are presented in this paper.Comment: 6 pages, 8 figures, submit to CP
Self-doping effect in confined copper selenide semiconducting quantum dots for efficient photoelectrocatalytic oxygen evolution
Self-doping can not only suppress the photogenerated charge recombination of
semiconducting quantum dots by self-introducing trapping states within the
bandgap, but also provide high-density catalytic active sites as the
consequence of abundant non-saturated bonds associated with the defects. Here,
we successfully prepared semiconducting copper selenide (CuSe) confined quantum
dots with abundant vacancies and systematically investigated their
photoelectrochemical characteristics. Photoluminescence characterizations
reveal that the presence of vacancies reduces the emission intensity
dramatically, indicating a low recombination rate of photogenerated charge
carriers due to the self-introduced trapping states within the bandgap. In
addition, the ultra-low charge transfer resistance measured by electrochemical
impedance spectroscopy implies the efficient charge transfer of CuSe
semiconducting quantum dots-based photoelectrocatalysts, which is guaranteed by
the high conductivity of their confined structure as revealed by
room-temperature electrical transport measurements. Such high conductivity and
low photogenerated charge carriers recombination rate, combined with
high-density active sites and confined structure, guaranteeing the remarkable
photoelectrocatalytic performance and stability as manifested by
photoelectrocatalysis characterizations. This work promotes the development of
semiconducting quantum dots-based photoelectrocatalysis and demonstrates CuSe
semiconducting quantum confined catalysts as an advanced photoelectrocatalysts
for oxygen evolution reaction
STUDY ON THE 3.5-CELL DC-SC PHOTO-INJECTOR*
Abstract In order to get high quality electron beam for PKU-ERL-FEL project. A 3.5-cell DC-SC photo-injector was designed and optimized. The pierce gun and 3.5-cell superconducting Nb cavity are DC acceleration section and RF acceleration section, respectively. A tuner for the whole 3.5-cell superconducting cavity has been designed. The beam parameters of 3.5-cell DC-SC photo-injector are also presented in this paper. The disadvantage and problem of 1.5-cell DC-SC photo cathode injector which was for principle demonstration have been overcame in the design of 3.5-cell DC-SC photo cathode injector
Study on the properties of autoclaved aerated concrete with high content concrete slurry waste
Concrete slurry waste is solid waste produced in the ready-mixed concrete industry, which will cause serious pollution to the environment. This paper mainly studies the physical and mechanical properties and microscopic products of autoclaved aerated concrete with high content concrete waste slurry. Attempts are made to improve the mechanical properties of the product by using nano-silica and silica fume. The flowability and gas foaming characteristics of the slurry, the dry density, the compressive strength, and the reaction product of the product were analyzed. The experimental results show that with the content of concrete slurry waste reaching 60%, the dry density and compressive strength of AAC are 470.5Â kg/m3 and 2.16Â MPa, respectively. On this basis, the dry density and compressive strength of AAC with the addition of 1% nano-silica and 7% silica fume are 512.8Â kg/m3, 3.05Â MPa, and 462.52Â kg/m3,2.86Â MPa, respectively
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Downregulation of long non-coding RNA LET predicts poor prognosis and increases Notch signaling in non-small cell lung cancer
Long non-coding RNAs (lncRNAs) have been found to be dysregulated in a variety of tumors. The lncRNA-Low Expression in Tumor (LET) is a recently identified lncRNA, but its expression pattern and biological significance in human non-small cell lung cancer (NSCLC) are still largely unknown. In this study, we found that lncRNA-LET was significantly downregulated in human NSCLC lung tissues and cell lines. Decreased lncRNA-LET expression was strongly associated with advanced tumor stages and poorer overall survival of NSCLC patients. Functionally, overexpression of lncRNA-LET in NSCLC H292 cells significantly suppressed cell proliferation, migration and invasion, and promoted cell cycle arrest and apoptosis, while knockdown of lncRNA-LET in NSCLC H1975 cells showed an opposite effect, pointing to a tumor-suppressive role for lncRNA-LET in NSCLC. Mechanistically, we demonstrated that lncRNA-LET overexpression significantly reduced the expression of Notch1 intracellular Domain (NICD1) in H292 cells while knockdown of lncRNA-LET increased NICD1 expression in H1975 cells. Similarly, NSCLC lung tissues with high levels of lncRNA-LET had lower NICD1 expression. Thus, our results provide a strong rationale for lncRNA-LET to be used as a prognostic indicator and a potent therapeutic target for NSCLC patients, and highlight a novel lncRNA-LET/Notch axis in regulating NSCLC cell fate and tumor progression
Maillard volatiles in baked products as affected by feruloylated oligosaccharides from maize bran
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