Time-Resolved Electron Transfer in Porphyrin-Coordinated Ruthenium Dimers: From Mixed-Valence Dynamics to Hot Electron Transfer

Presented here is the first effort to study the formation and dynamics of the triruthenium cluster (Ru₃O) pyrazine-bridged dimer mixed-valence state. Femtosecond transient absorption spectroscopy was implemented to follow photoinduced electron-transfer reactions in a series of asymmetric porphyrin-coordinated dyads, which form strongly coupled mixed-valence species upon single reduction. Excitation of the porphyrin subunit resulted in electron transfer to the Ru₃O dimer with a time constant τ ≈ 0.6 ps. The intramolecular electron transfer was confirmed by excitation of the Ru₃O MLCT, which resulted in the formation of a vibrationally unrelaxed porphyrin ground state. Under both excitation experiments, the back electron transfer was extremely fast (τ_CR < 0.1 ps), preventing complete time-resolved exploration of the mixed-valence state. These complexes enabled the observation of excited product states following electron-transfer processes, resulting from porphyrin S₁ and S₂ excitation. Although the charge recombination itself could not be observed, the yield of unrelaxed ground states supports the conclusion that delocalization takes place at least partially on a sub-100 fs time scale

Partial Discharge Characterization in a Defect Subjected to HVDC Cable Operating Conditions

In this work, the role of the electric conductivity on variations of the PD phenomenon in XLPE insulation under DC stress is investigated and demonstrated. To enable this investigation, a new experimental setup simulating the insulating layer of a cable with an embedded air void defect and subjected to a DC stress and temperature has been proposed. The setup consists of two flat specimens connected in series. One of them is heated while the other one, that contains the defect, is kept at ambient temperature. Consequently, the electric fields induced by the externally applied DC stress differ between the two specimens. In this way, a conductivity variation between two dielectric layers is obtained. To facilitate the usage of this method, a new simulation model related to the proposed experimental setup has also been developed. The model is an extension of the three-capacitor model, in which variable resistors are introduced. Both simulation and experimental results indicate that the introduced discrete thermal gradient results in higher conductivity values and enhanced PD activity

Impact of SARS-CoV-2 infection and COVID-19 on patients with inborn errors of immunity

Since the arrival of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in December 2019, its characterization as a novel human pathogen, and the resulting coronavirus disease 2019 (COVID-19) pandemic, over 6.5 million people have died worldwide-a stark and sobering reminder of the fundamental and nonredundant roles of the innate and adaptive immune systems in host defense against emerging pathogens. Inborn errors of immunity (IEI) are caused by germline variants, typically in single genes. IEI are characterized by defects in development and/or function of cells involved in immunity and host defense, rendering individuals highly susceptible to severe, recurrent, and sometimes fatal infections, as well as immune dysregulatory conditions such as autoinflammation, autoimmunity, and allergy. The study of IEI has revealed key insights into the molecular and cellular requirements for immune-mediated protection against infectious diseases. Indeed, this has been exemplified by assessing the impact of SARS-CoV-2 infection in individuals with previously diagnosed IEI, as well as analyzing rare cases of severe COVID-19 in otherwise healthy individuals. This approach has defined fundamental aspects of mechanisms of disease pathogenesis, immunopathology in the context of infection with a novel pathogen, and therapeutic options to mitigate severe disease. This review summarizes these findings and illustrates how the study of these rare experiments of nature can inform key features of human immunology, which can then be leveraged to improve therapies for treating emerging and established infectious diseases. (J Allergy Clin Immunol 2023;151:818-31.

Recessive inborn errors of type I IFN immunity in children with COVID-19 pneumonia

In an international cohort of 112 children hospitalized for moderate to critical COVID-19 pneumonia, we identified 12 children with one of four known recessive inborn errors of type I interferon immunity: X-linked TLR7 and autosomal IFNAR1, STAT2, and TYK2 deficiencies.Recessive or dominant inborn errors of type I interferon (IFN) immunity can underlie critical COVID-19 pneumonia in unvaccinated adults. The risk of COVID-19 pneumonia in unvaccinated children, which is much lower than in unvaccinated adults, remains unexplained. In an international cohort of 112 children (&lt;16 yr old) hospitalized for COVID-19 pneumonia, we report 12 children (10.7%) aged 1.5-13 yr with critical (7 children), severe (3), and moderate (2) pneumonia and 4 of the 15 known clinically recessive and biochemically complete inborn errors of type I IFN immunity: X-linked recessive TLR7 deficiency (7 children) and autosomal recessive IFNAR1 (1), STAT2 (1), or TYK2 (3) deficiencies. Fibroblasts deficient for IFNAR1, STAT2, or TYK2 are highly vulnerable to SARS-CoV-2. These 15 deficiencies were not found in 1,224 children and adults with benign SARS-CoV-2 infection without pneumonia (P = 1.2 x 10(-11)) and with overlapping age, sex, consanguinity, and ethnicity characteristics. Recessive complete deficiencies of type I IFN immunity may underlie similar to 10% of hospitalizations for COVID-19 pneumonia in children

Decoding the Human Genetic and Immunological Basis of COVID-19 mRNA Vaccine-Induced Myocarditis

No abstract availabl