In this work, the geometric and electronic
structure of N species
in N-doped carbon nanotubes (NCNTs) is derived by X-ray photoemission
(XPS) and absorption spectroscopy (NEXAFS) of the N 1s core excitation.
Substitutional N species in pyridine-like configuration and another
form of N with higher thermal stability are found in NCNTs. The structural
configuration of the high thermally stable N species, in the literature
often referred to as graphitic N, is assessed in this work by a combined
theoretical and experimental study as a 3-fold substitutional N species
in an NCNT basic structural unit (BSU). Furthermore, the nature of
the interaction of those N species with a Pd metal center immobilized
onto NCNTs is of σ-type donation from the filled π-orbital
of the N atom to the empty d-orbital of the Pd atom and a π
back-donation from the filled Pd atomic d-orbital to the π*
antibonding orbital of the N atom. We have found that the interaction
of pyridine N with Pd is characterized by a charge transfer typical of a covalent chemical
bond with partial ionic character, consistent with the chemical shift
observed in the Pd 3d core level of divalent Pd. Graphitic N sites
interact with Pd by a covalent bond without any charge redistribution.
In this case, the electronic state of the Pd corresponds to metallic
Pd nanoparticles electronically modified by the interaction with the
support. The catalytic reactivity of these samples in hydrogenation,
CO oxidation, and oxygen reduction reaction (ORR) allowed clarifying
some aspects of the metal carbon support interaction in catalysis.
Cytokine storm and multi-organ failure are the main causes of SARS-CoV-2-related death. However, the origin of excessive damages caused by SARS-CoV-2 remains largely unknown. Here we show that the SARS-CoV-2 envelope (2-E) protein alone is able to cause acute respiratory distress syndrome (ARDS)-like damages in vitro and in vivo. 2-E proteins were found to form a type of pH-sensitive cation channels in bilayer lipid membranes. As observed in SARS-CoV-2-infected cells, heterologous expression of 2-E channels induced rapid cell death in various susceptible cell types and robust secretion of cytokines and chemokines in macrophages. Intravenous administration of purified 2-E protein into mice caused ARDS-like pathological damages in lung and spleen. A dominant negative mutation lowering 2-E channel activity attenuated cell death and SARS-CoV-2 production. Newly identified channel inhibitors exhibited potent anti-SARS-CoV-2 activity and excellent cell protective activity in vitro and these activities were positively correlated with inhibition of 2-E channel. Importantly, prophylactic and therapeutic administration of the channel inhibitor effectively reduced both the viral load and secretion of inflammation cytokines in lungs of SARS-CoV-2-infected transgenic mice expressing human angiotensin-converting enzyme 2 (hACE-2). Our study supports that 2-E is a promising drug target against SARS-CoV-2.
Chiral hole: The first chiral microporous germanium antimony sulfide with 3D helical channels was constructed by the unprecedented combination of {GeS4} tetrahedra and ψ‐{SbS4} trigonal bipyramids. The dimethylammonium cations present in the structure are easily exchanged with alkali metal cations present in aqueous solution. The title compound has high ion‐exchange capacity and high selectivity for Cs+ ions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.