1,680 research outputs found
Understanding the internal structures of the , , and
We investigate the newly observed and based on the
diquark-antidiquark configuration within the framework of QCD sum rules. Both
of them may be interpreted as the -wave tetraquark states
of , but with opposite color structures, which is remarkably similar
to the result obtained in Ref.~\cite{Chen:2010ze} that the and
can be both interpreted as the -wave tetraquark
states of , also with opposite color structures. However, the
extracted masses and these suggested assignments to these states do depend
on these running quark masses where m_s (2 \mbox{ GeV}) = 95 \pm 5 MeV and
GeV. As a byproduct, the masses of the
hidden-bottom partner states of the and are extracted to be
both around 10.64 GeV, which can be searched for in the
invariant mass distribution.Comment: 6 pages, 4 figures. Accepted by Eur. Phys. J.
resonance as a tetraquark state and its isospin partner
We systematically construct tetraquark currents of and
classify them into types (antisymmetric), (symmetric)
and (mixed), based on flavor symmetries of diquarks and
antidiquarks composing the tetra quark currents. We use tetraquark currents of
type to perform QCD sum rule analyses, and find a tetraquark
current with quark contents ( or )
leading to a mass of GeV consistent with the state
recently observed by the COMPASS collaboration. Our results support tetraquark
explanations for both and , assuming that they are
isospin partners. We also study their possible decay patterns. As tetraquark
candidates, the possible decay modes of are -wave and -wave while
the possible decay patterns of are -wave and -wave . We speculate that
is partly responsible for the large isospin violation in the
decay mode which is reported by BESIII
collaboration in the process.Comment: 15 pages, 8 figures. Accepted by Phys. Rev.
Successful treatment of thrombotic thrombocytopenic purpura associated with mitral valve replacement
Study on Ammonia-induced Catalyst Poisoning in the Synthesis of Dimethyl Oxalate
On an industrial plant, we observed and examined the ammonia-poisoning catalyst for the synthesis of dimethyl oxalate (DMO). We investigated the catalytic activity in response to the amount of ammonia and revealed the mechanism of such poisoning by X-ray photoelectron spectroscopy (XPS) characterization. Our results show that only 0.002% ammonia in the feed gas can significantly deactivate the Pd-based catalyst. Two main reasons were proposed: one is that the competitive adsorption of ammonia on the active component Pd hinders the carbon monoxide (CO) coupling reaction and the redox cycle between Pd0 and Pd2+; and the other is that the high-boiling nitrogen-containing amine compounds formed by reacting with ammonia have adsorbed on the catalyst, which hinders the progress of the catalytic reaction. The deactivation caused by the latter is irreversible. The catalytic activity can be completely restored by a low-temperature liquid-phase in-situ regeneration treatment. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).
Type I IFN induces protein ISGylation to enhance cytokine expression and augments colonic inflammation
Type I IFNs have broad activity in tissue inflammation and malignant progression that depends on the expression of IFN-stimulated genes (ISGs). ISG15, one such ISG, can form covalent conjugates to many cellular proteins, a process termed "protein ISGylation." Although type I IFNs are involved in multiple inflammatory disorders, the role of protein ISGylation during inflammation has not been evaluated. Here we report that protein ISGylation exacerbates intestinal inflammation and colitis-associated colon cancer in mice. Mechanistically, we demonstrate that protein ISGylation negatively regulates the ubiquitin-proteasome system, leading to increased production of IFN-induced reactive oxygen species (ROS). The increased cellular ROS then enhances LPS-induced activation of p38 MAP kinase and the expression of inflammation-related cytokines in macrophages. Thus our studies reveal a regulatory role for protein ISGylation in colonic inflammation and its related malignant progression, indicating that targeting ubiquitin-activating enzyme E1 homolog has therapeutic potential in treating inflammatory diseases
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