100 research outputs found

    Mechanical Isolation of Highly Stable Antimonene under Ambient Conditions

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    Using mechanical exfoliation combined with a controlled double step transfer procedure we demonstrate that single layers of antimony can be readily produced. These flakes are not significantly contaminated upon exposure to ambient conditions and they do not react with water. DFT calculations confirm our experimental observations and predict a band gap of 1.2-1.3 eV (ambient conditions) for single layer antimonene, which is smaller than that calculated under vacuum conditions at 0 K. Our work confirms antimonene as a highly stable 2D material with promising relevant applications in optoelectronics.Comment: main paper: 5 pages, 4 figures supporting: 9 pages, 7 figures, Advanced Materials, 201

    Collective modes of coupled phase oscillators with delayed coupling

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    We study the effects of delayed coupling on timing and pattern formation in spatially extended systems of dynamic oscillators. Starting from a discrete lattice of coupled oscillators, we derive a generic continuum theory for collective modes of long wavelength. We use this approach to study spatial phase profiles of cellular oscillators in the segmentation clock, a dynamic patterning system of vertebrate embryos. Collective wave patterns result from the interplay of coupling delays and moving boundary conditions. We show that the phase profiles of collective modes depend on coupling delays.Comment: 5 pages, 2 figure

    Transcriptional portrait of M. bovis BCG during biofilm production shows genes differentially expressed during intercellular aggregation and substrate attachment.

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    Mycobacterium tuberculosis and M. smegmatis form drug-tolerant biofilms through dedicated genetic programs. In support of a stepwise process regulating biofilm production in mycobacteria, it was shown elsewhere that lsr2 participates in intercellular aggregation, while groEL1 was required for biofilm maturation in M. smegmatis. Here, by means of RNA-Seq, we monitored the early steps of biofilm production in M. bovis BCG, to distinguish intercellular aggregation from attachment to a surface. Genes encoding for the transcriptional regulators dosR and BCG0114 (Rv0081) were significantly regulated and responded differently to intercellular aggregation and surface attachment. Moreover, a M. tuberculosis H37Rv deletion mutant in the Rv3134c-dosS-dosR regulon, formed less biofilm than wild type M. tuberculosis, a phenotype reverted upon reintroduction of this operon into the mutant. Combining RT-qPCR with microbiological assays (colony and surface pellicle morphologies, biofilm quantification, Ziehl-Neelsen staining, growth curve and replication of planktonic cells), we found that BCG0642c affected biofilm production and replication of planktonic BCG, whereas ethR affected only phenotypes linked to planktonic cells despite its downregulation at the intercellular aggregation step. Our results provide evidence for a stage-dependent expression of genes that contribute to biofilm production in slow-growing mycobacteria

    Evolutionary and functional history of the Escherichia coli K1 capsule

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    Escherichia coli is a leading cause of invasive bacterial infections in humans. Capsule polysaccharide has an important role in bacterial pathogenesis, and the K1 capsule has been firmly established as one of the most potent capsule types in E. coli through its association with severe infections. However, little is known about its distribution, evolution and functions across the E. coli phylogeny, which is fundamental to elucidating its role in the expansion of successful lineages. Using systematic surveys of invasive E. coli isolates, we show that the K1-cps locus is present in a quarter of bloodstream infection isolates and has emerged in at least four different extraintestinal pathogenic E. coli (ExPEC) phylogroups independently in the last 500 years. Phenotypic assessment demonstrates that K1 capsule synthesis enhances E. coli survival in human serum independent of genetic background, and that therapeutic targeting of the K1 capsule re-sensitizes E. coli from distinct genetic backgrounds to human serum. Our study highlights that assessing the evolutionary and functional properties of bacterial virulence factors at population levels is important to better monitor and predict the emergence of virulent clones, and to also inform therapies and preventive medicine to effectively control bacterial infections whilst significantly lowering antibiotic usage

    Microbial colonization and resistome dynamics in food processing environments of a newly opened pork cutting industry during 1.5 years of activity

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    Artículo versión publicadaBackground: The microorganisms that inhabit food processing environments (FPE) can strongly influence the associated food quality and safety. In particular, the possibility that FPE may act as a reservoir of antibiotic-resistant microorganisms, and a hotspot for the transmission of antibiotic resistance genes (ARGs) is a concern in meat processing plants. Here, we monitor microbial succession and resistome dynamics relating to FPE through a detailed analysis of a newly opened pork cutting plant over 1.5 years of activity. Results: We identified a relatively restricted principal microbiota dominated by Pseudomonas during the first 2 months, while a higher taxonomic diversity, an increased representation of other taxa (e.g., Acinetobacter, Psychrobacter), and a certain degree of microbiome specialization on different surfaces was recorded later on. An increase in total abundance, alpha diversity, and β-dispersion of ARGs, which were predominantly assigned to Acinetobacter and associated with resistance to certain antimicrobials frequently used on pig farms of the region, was detected over time. Moreover, a sharp increase in the occurrence of extended-spectrum β-lactamase- producing Enterobacteriaceae and vancomycin-resistant Enterococcaceae was observed when cutting activities started. ARGs associated with resistance to β-lactams, tetracyclines, aminoglycosides, and sulphonamides frequently co-occurred, and mobile genetic elements (i.e., plasmids, integrons) and lateral gene transfer events were mainly detected at the later sampling times in drains. Conclusions: The observations made suggest that pig carcasses were a source of resistant bacteria that then colonized FPE and that drains, together with some food-contact surfaces, such as equipment and table surfaces, represented a reservoir for the spread of ARGs in the meat processing facility.S

    combined pik3ca and fgfr inhibition with alpelisib and infigratinib in patients with pik3ca mutant solid tumors with or without fgfr alterations

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    PURPOSE Concurrent PIK3CA mutations and fibroblast growth factor receptor (FGFR) alterations occur in multiple cancer types, including estrogen receptor–positive breast cancer, bladder cancer, and endometrial cancer. In this first-in-human combination trial, we explored safety and preliminary efficacy of combining the PI3Kα selective inhibitor alpelisib with the FGFR1-4 selective inhibitor infigratinib. PATIENTS AND METHODS Patients with PIK3CA-mutant advanced solid tumors, with or without FGFR1-3 alterations, were enrolled in the dose escalation or one of three molecular-defined dose-expansion cohorts. The primary end point was the maximum tolerated dose. Secondary end points included safety, pharmacokinetics, and response. Archival tumor samples were sequenced to explore genomic correlates of response. RESULTS In combination, both agents were escalated to full, single-agent recommended doses (alpelisib, 300 mg per day continuously; infigratinib, 125 mg per day 3 weeks on followed by 1 week off). The toxicity profile of the combination was consistent with the established safety profile of each agent, although 71% of all patients required at least one treatment interruption or dose reduction. Molecularly selected dose expansions in breast cancer and other solid tumors harboring PIK3CA mutations, alone or in combination with FGFR alterations, identified sporadic responses, predominately in tumor types and genotypes previously defined to have sensitivity to these agents. CONCLUSION The combination of alpelisib and infigratinib can be administered at full single-agent doses, although the high rate of dose interruption or reduction suggests long-term tolerability may be challenging. In exploratory signal-seeking cohorts of patients harboring dual PIK3CA and FGFR1-3 alterations, no clear evidence of synergistic activity was observed
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