Crystal field effects on the reactivity of aluminum-copper cluster anions

The limits and useful modifications of the jellium model are of great interest in understanding the properties of metallic clusters, especially involving bimetallic systems. We have measured the relative reactivity of CuAl−n clusters (n=11–34) with O2. An odd-even alternation is observed that is in accordance with spin-dependant etching, and CuAl−22is observed as a “magic peak.” The etching resistance of CuAl−22 is explained by an unusually large splitting of the 2D10 subshell that occurs because of a geometric distortion of the cluster that may also be understood as a crystal field splitting of the superatomic orbitals

Predicting disordered regions driving phase separation of proteins under variable salt concentration

We determine the intrinsically disordered regions (IDRs) of phase separating proteins and investigate their impact on liquid-liquid phase separation (LLPS) with a random-phase approx- imation (RPA) that accounts for variable salt concentration. We focus on two proteins, PGL-3 and FUS, known to undergo LLPS. For PGL-3 we predict that an IDR near the C-terminus pro- motes LLPS, which we validate through direct comparison with in vitro experimental results. For the structurally more complex protein FUS the role of the low complexity (LC) domain in LLPS is not as well understood. Apart from the LC domain we here identify two IDRs, one near the N-terminus and another near the C-terminus. Our RPA analysis of these domains predict that, surprisingly, the IDR at the N-terminus (aa 1-285) and not the LC domain promotes LLPS of FUS by comparison to in vitro experiments under physiological temperature and salt conditions

Evaluating the e-Cigarette Epidemic in US Emergency Departments

Background: Electronic cigarettes (e-cigarettes) are often thought to be a healthier option to cigarette smoking. e-Cigarettes have been found to overheat and explode. e-Cigarette explosions have caused severe trauma and rendered patients in critical conditions. Inadvertent exposures to liquid nicotine products have caused systemic poisoning injuries. We sought to characterize e-cigarette injuries presenting to emergency departments (ED) in 2018.Methods: We analyzed one year of data from the US Consumer Product Safety Commission’s National Electronic Injury Surveillance System (NEISS). Patients presenting with injuries associated with e-cigarette products were manually identified for inclusion. We performed descriptive analyses on demographic factors, affected bodily regions, dispositions, locations of occurrence, and mechanisms of injury. By applying sample weights, nationally representative estimates were calculated.Results: A total of 361 667 injury cases were reported in NEISS (2018). We identified 50 e-cigarette injury cases, generating a national estimate of 1739 (95% CI [1333-2148]) patients presenting to US EDs with e-cigarette injuries in 2018. Approximately 1000 pediatric patients (age ≤17 years) and 700 adult patients (age ≥18 years) were included. The median age when presenting to the ED was 4 years (interquartile range [IQR], 1-25). Over 85% of injuries occurred at home. Ingestion (55.0%) was the most common mechanism of injury, followed by explosion (35.8%).Conclusion: Children and adults are susceptible to injury from e-cigarette products. Changes in manufacturing standards may prevent injuries from these products

Closed-shell to split-shell stability of isovalent clusters

Metallic clusters containing 2, 8, 18, and 20 electrons are now known to exhibit enhanced stability that can be reconciled because of filled 1S, 1P, 1D, and 2S electronic shells within a simplified confined nearly free electron (NFE) gas. Here, we present first-principles studies on three isovalent clusters, i.e., ZnMg8, CuMg8−, and AuMg8−, each with 18 valence electrons. All the clusters exhibit local energetic stability but with differing origins. Although the stability of ZnMg8 can be reconciled within the conventional confined NFE picture with filled 1S2, 1P6, and 1D10shells, CuMg8− and AuMg8− are shown to be stable despite the unfilled D-shell. Their stability can be understood as a crystal field–like splitting of the otherwise degenerate D-shell because of internal electric fields of the positive ion cores that lead to a filled 1S2, 1P6, 1D8, 2S2 sequence separated by unfilled D2 states that form a large gap. We also examine the progression toward the metallic character in ZnMgn clusters, because isolated Mg and Zn atoms have filled valence 4s2 and 3s2 atomic states. As Mg atoms are added to a Zn atom, the excited atomic p-states in the Mg atoms hybridize rapidly with Zn and Mg s-states to promote a metallic character that evolves more rapidly than in pure Mgn clusters

Cooperative effects in the oxidation of CO by palladium oxide cations

Cooperative reactivity plays an important role in the oxidation of CO to CO2 by palladium oxide cations and offers insight into factors which influence catalysis. Comprehensive studies including guided-ion-beam mass spectrometry and theoretical investigations reveal the reaction products and profiles of PdO2 + and PdO3 + with CO through oxygen radical centers and dioxygen complexes bound to the Pd atom. O radical centers are more reactive than the dioxygen complexes, and experimental evidence of both direct and cooperative CO oxidation with the adsorption of two CO molecules are observed. The binding of multiple electron withdrawing CO molecules is found to increase the barrier heights for reactivity due to decreased binding of the secondary CO molecule, however, reactivity is enhanced by the increase in kinetic energy available to hurdle the barrier. We examine the effect of oxygen sites, cooperative ligands, and spin including two-state reactivity

New knowledge of the earth's atmosphere from the aeronomy satellite /explorer xvii/

Explorer XVII satellite measurements of upper atmospher