Electronic and Lattice Distortions Induce Elastic Softening in Refractory Multicomponent Borides

Borides are extensively employed in applications demanding exceptionally high hardness, which arises from the unique and strong crystallographic arrangement of boron atoms therein. Addition of multiprincipal elements in borides is expected to enhance their structural properties due to lattice distortion and high configurational entropy. In contrast, we unravel a phenomenon of elastic softening in refractory multicomponent borides from first-principle predictions, which concur with experimentally determined metrics in their single-phase multiprincipal element counterparts. The reductions in the bulk and Young’s modulus of these compounds are attributed to the lengthening and distortion of the boron–boron bonds and angles, but more critically to the perturbation in the charge densities arising from the different cations and the consequential increase in statistical weights of the d5 configuration states of the transition metals present in the boride.

N-acyl homoserine lactone mediated interspecies interactions between <i>A. baumannii</i> and <i>P. aeruginosa</i>

<div><p> <i>Acinetobacter baumannii</i> and <i>Pseudomonas aeruginosa</i> are pathogens capable of colonizing the same infection sites and employing N-acyl homoserine lactone (AHL) based quorum-sensing systems to co-ordinate biofilm formation. Hence, the effect of <i>P. aeruginosa</i> AHLs on biofilm formation by <i>A. baumannii</i> and <i>vice versa</i> were investigated using the biofilm impaired quorum sensing mutants, <i>A. baumannii</i> M2 (<i>aba</i>I::Km) and <i>P. aeruginosa</i> PAO-JP2. Complementing the mutants with heterologous, extracted and pure AHLs increased biofilm mass significantly. The surface area coverage and biovolume also increased significantly as observed by confocal scanning laser microscopy which corroborated scanning electron microscope analysis. Autoinducer synthase gene promoters of <i>A. baumannii</i>, P_<i>aba</i>I-<i>lac</i>Z, and <i>P. aeruginosa</i>, P_<i>las</i>I-<i>lacZ</i>, were induced (<i>p</i> < 0.05) by heterologous AHLs. Growth of <i>A. baumannii</i> was not inhibited by pyocyanin of <i>P. aeruginosa</i> which may allow their co-existence and interaction in the clinical setting, thereby affecting the severity of combined infections and therapeutic measures to control them.</p> </div

Additional file 9: of Quorum sensing in thermophiles: prevalence of autoinducer-2 system

Multiple sequence alignment of SAH hydrolase from thermophilic and mesophilic eubacteria by MultAlin. High conservation among SAH hydrolases has been observed. (PDF 274 kb

Additional file 5: of Quorum sensing in thermophiles: prevalence of autoinducer-2 system

Multiple sequence alignment of ComA protein from Bacillus subtilis and thermophilic eubacteria by MultAlin. (PDF 120 kb

Additional file 6: of Quorum sensing in thermophiles: prevalence of autoinducer-2 system

Multiple sequence alignment of LuxS protein from mesophilic and thermophilic eubacteria by MultAlin. Invariant residues are highlighted in red colour. The conserved HTLEH motif and other conserved residues are highlighted within boxes. (PDF 111 kb

Additional file 14: of Quorum sensing in thermophiles: prevalence of autoinducer-2 system

STRING analysis of LuxS protein of Geobacillus thermoglucosidasius. (PDF 225 kb

Additional file 12: of Quorum sensing in thermophiles: prevalence of autoinducer-2 system

Multiple sequence alignment of RbsB protein from mesophilic and thermophilic eubacteria by MultAlin. Conserved residues are highlighted in red within boxes. (PDF 142 kb

Additional file 3: of Quorum sensing in thermophiles: prevalence of autoinducer-2 system

Multiple sequence alignment of AgrA protein from Staphylococcus aureus and thermophilic eubacteria by MultAlin. (PDF 40 kb

Relative expression of <i>lasIR</i> and <i>rhlIR</i> genes of <i>P. aeruginosa</i> PAO1 in the presence of 0.5 mg/ml F7 as determined by qRT PCR.

<p>Relative expression of <i>lasIR</i> and <i>rhlIR</i> genes of <i>P. aeruginosa</i> PAO1 in the presence of 0.5 mg/ml F7 as determined by qRT PCR.</p

Additional file 15 of Quorum sensing in thermophiles: prevalence of autoinducer-2 system

STRING analysis of LuxS protein of Caminibacter mediatlanticus. (PDF 90 kb