Is AlOH the Astrochemical Reservoir Molecule of AlO?: Insights from Excited Electronic States

Very recently, the optical bands of the 2Σ+ ← X2Σ+system of AlO have been identified in the red supergiant star VYCMa. In an effort to explain the origin of this transition, we used state-of-the-art quantum chemical calculations with proven high accuracy to compute the lowest singlet and triplet electronic states of the AlOH and HAlO isomers as well as their equilibrium geometry and electronic properties. Our calculated potential energy surfaces implicate the three singlet electronic states 21A′, 31A′, and 11A″ in the photodissociation of the [Al,O,H] system. Only AlO, H, Al, and OH products can occur through the photodissociation of [Al,O,H]; AlH and O are not allowed. For the photodissociation of AlOH, the AlO product can occur only in its excited states AlO(2Π) and AlO(2Σ+)

Toward the detection of the triatomic negative ion SPN−: Spectroscopy and potential energy surfaces

High level theoretical calculations using coupled-cluster theory were performed to provide an accurate description of the electronic structure, spectroscopic properties, and stability of the triatomic negative ion comprising S, N, and P. The adiabatic electron affinities (AEAs) and vertical detachment energies (VDEs) of PNS, SPN, PSN, and cyc-PSN were calculated. The predicted AEA and VDE of the linear SPN isomer are large: 2.24 and 3.04 eV, respectively. The potential energy surfaces (PESs) of the lowest-lying electronic states of the SPN isomer along the PN and SP bond lengths and bond angle were mapped. A set of spectroscopic parameters for SPN, PNS, and PSN in their electronic ground states is obtained from the 3D PESs to help detect these species in the gas phase. The electronic excited state SPN (12A”) is predicted to be stable with a long lifetime calculated to be 189.7 µs. The formation of SPN in its electronic ground state through the bimolecular collision between S + PN and N + PS is also discussed

Molecular oxygen generation from the reaction of water cations with oxygen atoms

© 2019 Author(s). The oxywater cation (H2OO+), previously shown to form barrierlessly in the gas phase from water cations and atomic oxygen, is proposed here potentially to possess a 2A″ ← 4A″ excitation leading to the H2⋯O2+ complex. This complex could then easily decompose into molecular hydrogen and the molecular oxygen cation. The present quantum chemical study shows that the necessary electronic transition takes place in the range of 1.92 eV (645 nm), in the orange-red range of the visible and solar spectrum, and dissociation of the complex only requires 5.8 kcal/mol (0.25 eV). Such a process for the abiotic, gas phase formation of O2 would only need to be photocatalyzed by visible wavelength photons. Hence, such a process could produce O2 at the mesosphere/stratosphere boundary as climate change is driving more water into the upper atmosphere, in the comet 67P/Churyumov-Gerasimenko where surprisingly high levels of O2 have been observed, or at gas-surface (ice) interfaces

Estimation of Abbreviated Cyclosporine A Area under the Concentration-Time Curve in Allogenic Stem Cell Transplantation after Oral Administration

Measurements of Cyclosporine (CsA) systemic exposure permit its dose adjustment in allogenic stem cell transplantation recipients to prevent graft-versus-host disease. CsA LSSs were developed and validated from 60 ASCT patients via multiple linear regressions. All whole-blood samples were analyzed by fluorescence polarization immunoassay (FPIA-Axym). The 10 models that have used CsA concentrations at a single time point did not have a good fit with AUC0–12 (R2 < 0.90). C2 and C4 were the time points that correlated best with AUC0–12 h, R2 were respectively 0.848, and 0.897. The LSS equation with the best predictive performance (bias, precision and number of samples) utilized three sampling concentrations was AUC0–12 h = 0.607 + 1.569 × C0.5 + 2.098 × C2 + 3.603 × C4 (R2 = 0.943). Optimal LSSs equations which limited to those utilizing three timed concentrations taken within 4 hours post-dose developed from ASCT recipient's patients yielded a low bias <5% ranged from 1.27% to 2.68% and good precision <15% ranged from 9.60% and 11.02%. We propose an LSS model with equation AUC0–12 h = 0.82 + 2.766 × C2 + 3.409 × C4 for a practical reason. Bias and precision for this model are respectively 2.68% and 11.02%

Numerical modeling of shape memory alloy problem in presence of perturbation: application to Cu-Al-Zn-Mn specimen

This paper proposes a methodology for taking into consideration uncertainties based on polynomial chaos (PC). The proposed approach is used in order to determine the response of Cu-Al-Zn-Mn shape memory alloy specimen with uncertainties associated to material parameters. The simulation results are obtained by PC method. The proposed method seems to be an efficient probabilistic tool. It is worth mentioning that PC approach is an interesting alternative for the parametric studies. This technique is more efficient compared to MC approach

Optimisation fiabiliste d’une structure en alliage à mémoire de forme

L’objectif de l’optimisation fiabiliste (RBDO) est de trouver le meilleur compromis entre la sécurité et le coût. Plusieurs méthodes, telles que la méthode hybride (HM) et la méthode des facteurs optimaux de sûreté (OSF), sont développées pour atteindre cet objectif. Ces méthodes ont été appliquées uniquement pour les matériaux usuels. Néanmoins, le progrès effectué dans le domaine de l’élaboration de matériaux a conduit à l’utilisation des matériaux “intelligents” tel qua l’alliage à mémoire de forme (SMA). Dans ce papier, nous proposons une extension de ces méthodes dans le cas des structures formées en SMA pour étudier l’efficacité des méthodes proposées

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Is AlOH the Astrochemical Reservoir Molecule of AlO?: Insights from Excited Electronic States

Very recently, the optical bands of the 2Σ+ ← X2Σ+system of AlO have been identified in the red supergiant star VYCMa. In an effort to explain the origin of this transition, we used state-of-the-art quantum chemical calculations with proven high accuracy to compute the lowest singlet and triplet electronic states of the AlOH and HAlO isomers as well as their equilibrium geometry and electronic properties. Our calculated potential energy surfaces implicate the three singlet electronic states 21A′, 31A′, and 11A″ in the photodissociation of the [Al,O,H] system. Only AlO, H, Al, and OH products can occur through the photodissociation of [Al,O,H]; AlH and O are not allowed. For the photodissociation of AlOH, the AlO product can occur only in its excited states AlO(2Π) and AlO(2Σ+)

Toward the detection of the triatomic negative ion SPN−: Spectroscopy and potential energy surfaces

High level theoretical calculations using coupled-cluster theory were performed to provide an accurate description of the electronic structure, spectroscopic properties, and stability of the triatomic negative ion comprising S, N, and P. The adiabatic electron affinities (AEAs) and vertical detachment energies (VDEs) of PNS, SPN, PSN, and cyc-PSN were calculated. The predicted AEA and VDE of the linear SPN isomer are large: 2.24 and 3.04 eV, respectively. The potential energy surfaces (PESs) of the lowest-lying electronic states of the SPN isomer along the PN and SP bond lengths and bond angle were mapped. A set of spectroscopic parameters for SPN, PNS, and PSN in their electronic ground states is obtained from the 3D PESs to help detect these species in the gas phase. The electronic excited state SPN (12A”) is predicted to be stable with a long lifetime calculated to be 189.7 µs. The formation of SPN in its electronic ground state through the bimolecular collision between S + PN and N + PS is also discussed