A Timeframe for SARS-CoV-2 Genomes: A Proof of Concept for Postmortem Interval Estimations

Establishing the timeframe when a particular virus was circulating in a population could be useful in several areas of biomedical research, including microbiology and legal medicine. Using simulations, we demonstrate that the circulation timeframe of an unknown SARS-CoV-2 genome in a population (hereafter, estimated time of a queried genome [QG]; t_E-QG) can be easily predicted using a phylogenetic model based on a robust reference genome database of the virus, and information on their sampling dates. We evaluate several phylogeny-based approaches, including modeling evolutionary (substitution) rates of the SARS-CoV-2 genome (~10⁻³ substitutions/nucleotide/year) and the mutational (substitutions) differences separating the QGs from the reference genomes (RGs) in the database. Owing to the mutational characteristics of the virus, the present Viral Molecular Clock Dating (VMCD) method covers timeframes going backwards from about a month in the past. The method has very low errors associated to the t_E-QG estimates and narrow intervals of t_E-QG, both ranging from a few days to a few weeks regardless of the mathematical model used. The SARS-CoV-2 model represents a proof of concept that can be extrapolated to any other microorganism, provided that a robust genome sequence database is available. Besides obvious applications in epidemiology and microbiology investigations, there are several contexts in forensic casework where estimating t_E-QG could be useful, including estimation of the postmortem intervals (PMI) and the dating of samples stored in hospital settings.     

Hot corrosion Type II of FeCr‐based model alloys for boiler and heat exchanger applications

The hot corrosion Type II of the alloys FeCr20, FeCr20Ni10, FeCr20Ni20, and FeCr20Co10 is investigated at 700°C in air + 0.5% SO₂ with deposits consisting of Na₂SO₄ and a eutectic mixture of Na₂SO₄ and MgSO₄ for 24, 100, and 300 h. The alloying elements nickel and cobalt have a positive influence when tests are conducted using a MgSO₄‐Na₂SO₄ deposit. In this case, they reduce the metal loss and increase the time to the propagation stage. In contrast, when the alloys are exposed with a Na₂SO₄ deposit, these alloying elements increase the metal loss and allow for the transition to the propagation stage because they can form molten phases with the Na₂SO₄. During the incubation stage an oxide scale forms on the FeCr20 alloy, which is thicker than the one formed during exposure without a deposit, and iron oxides are observed, which precipitate in the deposit. The propagation stage occurs by a dissolution and precipitation mechanism forming localized pitting attack. Iron is the main species that dissolves and precipitates, while chromium remains mainly as an oxide beneath the initial surface. The additional elements are found in the pit and in the salt deposit.     

Ethyl group as matrix modifier and inducer of ordered domains in hybrid xerogels synthesised in acidic media using ethyltriethoxysilane (ETEOS) and tetraethoxysilane (TEOS) as precursors

Hybrid silica xerogels favourably combine the properties of organic and inorganic components in one material; consequently these materials are useful for multiple applications. The versatility and mild synthetic conditions provided by the sol-gel process are ideal for the synthesis of hybrid materials. The specific aims of this study were to synthesise hybrid xerogels in acidic media using tetraethoxysilane (TEOS) and ethyltriethoxysilane (ETEOS) as silica precursors, and to assess the role of the ethyl group as a matrix modifier and inducer of ordered domains in xerogels. All xerogels were synthesised at pH 4.5, at 60 °C, with 1:4.75:5.5 TEOS:EtOH:H₂O molar ratio. Gelation time exponentially increased with the ETEOS molar ratio. Incorporation of the ethyl groups into the structure of xerogels reduced cross-linking, increased the average siloxane bond length, and promoted the formation of ordered domains. As a result, a transition from Qⁿ to Tⁿ signals detected in the ²⁹Si NMR spectra, the Si–O structural band in the FTIR spectra shifted to lower wavelength, and a new peak in the XRD pattern at 2θ < 10° appeared in the XRD patterns. Mass spectroscopy detected fragments with high numbers of silicon atoms and a polymeric distribution.     

Feasibility study of the cut and weld operations by RH on the cooling pipes of ITER NB components

The maintenance operations of ITER NB components inside the vessel - Beam Line Components (BLC's) involve the removal of the faulty component, its transport to the hot cell as well as the reverse operations of transport of the repaired/new component and its reinstallation inside the vessel. Prior to the removal of the BLC's the cooling pipes must be detached from the component following a procedure that applies to the cutting of the pipes and subsequent welding when the component is re-installed. The purpose of this study, conducted in the framework of EFDA, is to demonstrate the feasibility of the cut and weld operations on the water pipes of the BLC's using fully remote handling techniques. Viable technologies for the cut and weld operations have been identified within the study; in particular the following aspects will be presented in the paper:

• Different strategies can be pursued in the detachment of the components depending on the number of cut and weld operations to be performed on the pipes. The selected strategy will impact on the procedure to be followed likewise on important aspects as the requirements of the flexible joints assembled on the pipes.

• The existing cutting techniques have been examined in the light of the remotely performed pipe cutting at the NB cell. Modifications of commercial tools have been proposed in order to adapt them to the BLC's pipes requirements. The debris produced during the cutting process must be controlled and collected, therefore a cleaning system has been integrated in the adapted cutting tool referred above.

• The existing welding techniques have been also examined and compared based on different criteria such as complexity, reliability, alignment tolerances, etc. TIG welding is the preferred technique as it stands out for its superior performance. The commercial tools identified need to be adapted to the NB environment.

• The alignment of the pipes is a critical issue concerning the remote welding. A proper alignment system has been proposed taking into account the pre-selected welding technique.

Measures of specificity of fuzzy sets under T-indistinguishabilities

The concept of measure of specificity of fuzzy sets is extended in this paper to measure of specificity under the knowledge of T-indistinguishabilities. Four axioms of measure of specificity under T-indistinguishabilities are given. An algorithm to compute the inference independent set /spl Tfr/ from a fuzzy set and a T-indistinguishability is used to measure the specificity of fuzzy sets under T-indistinguishabilities satisfying the axioms.     

The effects of an electrostatic field and air stream on water jet break-up length

An experimental study of the break-up length of a circular section liquid jet subject to the combined action of a coaxial airstream and an electrostatic field is reported. A high speed photographic technique has been employed and the results have been correlated empirically by the following dimensionless equation: where “b” and “k” are functions of Reynolds number.     

Tuning Memristivity by Varying the Oxygen Content in a Mixed Ionic–Electronic Conductor

The rising interest shown for adaptable electronics and brain‐inspired neuromorphic hardware increases the need for new device architectures and functional materials to build such devices. The rational design of these memory components also benefits the comprehension and thus the control over the microscopic mechanisms at the origin of memristivity. In oxide‐based valence‐change memories, the control of the oxygen drift and diffusion kinetics is a key aspect in obtaining the gradual analog‐type change in resistance required for artificial synapse applications. However, only a few devices are designed with this in mind, as they are commonly built around ionic insulating active materials. This shortcoming is addressed by using a mixed ionic–electronic conductor as functional memristive material. This work demonstrates how the oxygen content in La₂NiO_4+δ (L2NO4), tuned through post‐annealing treatments, has a critical influence on the memory characteristics of L2NO4‐based memristive devices. The presence of interstitial oxygen point defects in L2NO4 affects both its structure and electrical properties. High oxygen stoichiometry in the pristine state leads to an increased electrical conductivity, ultimately resulting in an improved memory window with highly multilevel, analog‐type memory programing capabilities, desirable for analog computing and synaptic applications in particular.     

Unprecedented Improvement of Single Li‐Ion Conductive Solid Polymer Electrolyte Through Salt Additive

Solid‐state lithium metal (Li°) batteries (SSLMBs) are believed to be the most promising technologies to tackle the safety concerns and the insufficient energy density encountered in conventional Li‐ion batteries. Solid polymer electrolytes (SPEs) inherently own good processability and flexibility, enabling large‐scale preparation of SSLMBs. To minimize the growth of Li° dendrites and cell polarization in SPE‐based SSLMBs, an additive‐containing single Li‐ion conductive SPE is reported. The characterization results show that a small dose of electrolyte additive (2 wt%) substantially increases the ionic conductivity of single Li‐ion conductive SPEs as well as the interfacial compatibility between electrode and SPE, allowing the cycling of SPE‐based cells with good electrochemical performance. This work may provide a paradigm shift on the design of highly cationic conductive electrolytes, which are essential for developing safe and high‐performance rechargeable batteries.