MIS-C is a newly defined post-viral myocarditis and inflammatory vasculopathy of children following COVID-19 infection. This review summarizes the literature on diagnosis, parameters of disease severity, and current treatment regimens. The clinical perspective was analyzed in light of potential immunopathogenesis and compared to other post-infectious and inflammatory illnesses of children affecting the heart. In this paradigm, the evidence supports the importance of endothelial injury and activation of the IL-1 pathway as a common determinant among MIS-C, Kawasaki disease, and Acute Rheumatic fever.

Colloidal Mn 2+ -doped semiconductor nanocrystals are solution processable analogs of classic phosphor and diluted magnetic semiconductor materials with promising applications ranging from fluorescence microscopy to spintronic information processing. At doping levels of only a few cation mole percent, Mn 2+ dimers form in appreciable concentration and cause shortened photoluminescence decay times and reduced luminescence circular polarization under applied magnetic fields. Here, we show that these differences allow the use of timeresolved magnetophotoluminescence measurements to investigate the magnetic properties of the luminescent dimer excited state in Zn 1−x Mn x Se nanocrystals. These measurements reveal that Mn 2+ -Mn 2+ dimers are coupled ferromagnetically in their luminescent excited state, in contrast with the antiferromagnetic coupling of their ground state. We find that Mn 2+ -Mn 2+ dimers also luminesce with much purer circular polarization than Mn 2+ monomers under applied magnetic fields. These results are explained well by perturbation theory and density functional theory analyses of the microscopic orbital exchange interactions within the photoexcited Mn 2+ -Mn 2+ dimers. This discovery of photoswitchable dimer magnetism (from S = 0 to S = 4) with strong associated circularly polarized luminescence raises intriguing possibilities for optical spin manipulation in doped semiconductors.

The electronic structures of n-type ZnO nanocrystals formed via photochemical reduction and by aliovalent doping with aluminum are investigated using timedependent density functional theory. Connections between the density functional theory results and a simple quantummechanical particle-in-a-spherical-potential model are highlighted. Molecular orbitals obtained from density functional theory reveal the often-invoked S-, P-, D-, ... type "super" orbitals used to characterize the absorption spectra of these materials. ■ INTRODUCTIONColloidal semiconductor quantum dots (QDs) containing excess delocalized charge carriers play important roles in the development of devices for solar energy conversion, 1,2 IR plasmonics, 3−8 information processing, 9 and other technologies. Such n-or p-type semiconductor QDs have been prepared using remote doping, 10−15 photodoping, 3,13,16−22 aliovalent doping, 5,21,23−28 or electrochemical oxidation and reduction. 29−31 In most cases, aliovalent doping of colloidal semiconductor nanocrystals to yield band-like charge carriers has proven difficult because only a small fraction of dopant ions lead to charge carriers. 21,28,32 Recently, high-quality colloidal Al 3+ -doped ZnO (Al 3+ :ZnO) nanocrystals have been reported in which Al 3+ acts as an ionized shallow donor. 26 In these Al 3+ :ZnO nanocrystals, electronic absorption spectroscopy reveals excess band-like electrons, similar to those in photodoped ZnO (e − :ZnO) nanocrystals. 3,17−20,22,33−35 Explicit comparison of the electron paramagnetic resonance (EPR) and electron absorption spectra of Al 3+ :ZnO and e − :ZnO nanocrystals shows the two species are nearly indistinguishable. 21 Despite these similarities, however, they show qualitatively different chemical reactivity; Al 3+ :ZnO is completely stable against oxidation by O 2 , whereas e − :ZnO rapidly oxidizes when exposed to air. 13,[16][17][18]36,37 Consequently, while it is possible to determine the number of conduction band (CB) electrons per nanocrystal in photodoped ZnO nanocrystals via anaerobic titration with mild oxidants, 17,19,34 the stability of CB electrons in Al 3+ :ZnO nanocrystals prevents such characterization. Instead, the number of CB electrons in Al 3+ :ZnO nanocrystals has been estimated via EPR and absorption spectroscopies. NIR absorption increases, for example, as more electrons are added to the ZnO nanocrystals or as more Al 3+ is incorporated. 21Here we report the theoretical characterization of the lowenergy (ultraviolet/visible/near-infrared) electronic transitions of photodoped ZnO and Al 3+ :ZnO QDs using time-dependent hybrid density functional theory (TDDFT). We examine the electronic structures of the QDs using DFT, comparing the density of states for the two types of n-type QDs. We explore the connection between our computed DFT results and the simple quantum mechanical particle in a spherical potential model. 19,38,39 This theoretical characterization allows for direct comparison of the electronic structures of these two systems, offering uniq...

Abstract. Manganese-carrier magnetic exchange interactions in strongly quantum confined -conduction-band-electron interaction is described well using the recently proposed ferromagnetic kinetic s-s exchange pathway. Antiferromagnetic kinetic s-d exchange interactions previously proposed to become dominant in quantum confined diluted magnetic semiconductors (DMSs) have been evaluated quantitatively by both DFT and perturbation theory and are found to be weak compared to the ferromagnetic s-s interaction, even in these strongly confined QDs. The magnitudes of the mean-field exchange parameters are found to be nearly independent of quantum confinement over this range of QD diameters, and the dominant orbital pathways are not fundamentally altered by quantum confinement.i.

Ever use of NRT was common among this cohort of smokers, particularly among heavy smokers. Compared to nonusers, ever users of NRT were less likely to have stopped smoking and equally likely to cut down the frequency of smoking. This may reflect a tendency to turn to NRT for help after failing to quit by other means.

Decreases in the incidence of breast cancer have not been achieved, but there is a downward trend in age-adjusted breast cancer mortality rates in the United States. Recent epidemiologic investigations continue to refine our understanding of the role of established breast cancer risk factors, such as reproductive characteristics and body mass index, and in the process advance understanding of the etiology of breast cancer. Important strides are being made in the chemoprevention of breast cancer, but clarifying the potential contributions of factors such as diet, physical activity, and cigarette smoke to the breast cancer burden is a high priority because these lifestyle behaviors also have important implications for primary prevention. The role of both environmental and endogenous exposures in breast carcinogenesis will be more clearly elucidated by studies that account for genetic polymorphisms, some of which may lead to differential susceptibility to harmful agents.

The unique midgap excited states of Co2+-doped ZnO quantum dots have given rise to new applications in photocatalysis, sensing, magneto-optics, and magnetoelectronics. However, the electronic characteristics of these midgap transitions are not fully understood, and the uncertain interplay between these transitions has led to disagreement in the literature. In this work, midgap excited states of Co2+-doped ZnO quantum dots are analyzed using linear response time-dependent density functional theory and the effective mass theory with a focus on the geometry relaxation in the donor-type photoionization excited state. Relaxation of the excited-state geometry lowers the charge-transfer transition energy to be in the vicinity of the prominent spin-allowed 4A2 → 4T1 Co2+ d–d transition that gives this material its characteristic color. For large quantum dots, the excited-state population distribution between this Co2+ d–d excited state and the charge-transfer excited state can be tuned by thermal energy, resulting in a unique temperature dependence of the luminescence and photoconductivity.

The unique electronic structure of Mn 2+ -doped ZnO quantum dots gives rise to photoionization states that can be used to manipulate the magnetic state of the material and to generate zero-reabsorption luminescence. Fast formation and long non-radiative decay of this photoionization state is a necessary requirement for these important applications. In this work, surface hopping based non-adiabatic molecular dynamics are used to demonstrate the fast formation of a metal-to-ligand charge transfer state in a Mn 2+ -doped ZnO quantum dot. The formation occurs on an ultrafast timescale and is aided by the large density of states and significant mixing of the dopant Mn 2+ 3d t 2 levels with the valenceband levels of the ZnO lattice. The non-radiative lifetime of the photoionization states is also investigated.