The net emission coefficient of SF6-N2 mixtures was calculated for temperatures between 8000 and 24000 K and pressures between 1 and 8 bar. The calculation of the radiative transfer of the lines required a study of line broadening and was performed assuming that line overlapping had a negligible influence. The results show that the resonance lines, although they are strongly absorbed, make up a large part of the net radiation-about as much as the continuum. Also, the nitrogen lines are more strongly absorbed than the lines of sulphur or fluorine. At low temperatures the radiation of SF6 is stronger than that of nitrogen. When T>12000 K the net radiation of the mixture is not proportional to the net radiations of the gases owing to variations in emissivity and line broadening with temperature and composition of the mixture.

The computation of continuous absorption coefficient for SF6 plasmas has been carried out taking into account free-free radiation, using the scaled Thomas-Fermi potential for the determination of the terms resulting from the radiative recombination. The authors have computed the continuum absorption coefficient K' in SF6-N2 mixtures (for pressure values between 1 and 8 bar, in the temperature range 8000 to 24000 K) assuming that the plasma is in local thermodynamic equilibrium, by combining their results obtained in the case of SF6 with those concerning N2 from the literature. The evolution of K' with nu is explained in terms of electronic configuration of the species and of the variations of electron and ion densities with pressure, temperature and SF6 proportion.

The purpose of the study was to characterize the resistome, virulome, mobilome and Clustered Regularly Interspaced Short Palindromic Repeats-associated (CRISPR-Cas) system of extended-spectrum β-lactamase producing Klebsiella pneumoniae (ESBL-KP) clinical isolates and to determine their phylogenetic relatedness. The isolates were from Algeria, isolated at the University Hospital Establishment of Oran, between 2011 and 2012. ESBL-KP isolates (n = 193) were screened for several antibiotic resistance genes (ARGs) using qPCR followed by Pulsed-Field Gel Electrophoresis (PFGE). Representative isolates were selected from PFGE clusters and subjected to whole-genome sequencing (WGS). Genomic characterization of the WGS data by studying prophages, CRISPR-Cas systems, Multi-Locus Sequence Typing (MLST), serotype, ARGs, virulence genes, plasmid replicons, and their pMLST. Phylogenetic and comparative genomic were done using core genome MLST and SNP-Based analysis. Generally, the ESBL-KP isolates were polyclonal. The whole genome sequences of nineteen isolates were taken of main PFGE clusters. Sixteen sequence types (ST) were found including high-risk clones ST14, ST23, ST37, and ST147. Serotypes K1 (n = 1), K2 (n = 2), K3 (n = 1), K31 (n = 1), K62 (n = 1), and K151 (n = 1) are associated with hyper-virulence. CRISPR-Cas system was found in 47.4%, typed I-E and I-E*. About ARGs, from 193 ESBL-KP, the majority of strains were multidrug-resistant, the CTX-M-1 enzyme was predominant (99%) and the prevalence of plasmid-mediated quinolone resistance (PMQR) genes was high with aac(6′)-lb-cr (72.5%) and qnr’s (65.8%). From 19 sequenced isolates we identified ESBL, AmpC, and carbapenemase genes: blaCTX-M-15 (n = 19), blaOXA-48 (n = 1), blaCMY-2 (n = 2), and blaCMY-16 (n = 2), as well as non-ESBL genes: qnrB1 (n = 12), qnrS1 (n = 1) and armA (n = 2). We found IncF, IncN, IncL/M, IncA/C2, and Col replicon types, at least once per isolate. This study is the first to report qnrS in ESBL-KP in Algeria. Our analysis shows the concerning co-existence of virulence and resistance genes and would support that genomic surveillance should be a high priority in the hospital environment.

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