Observing the Growth of Pb₃O₄ Nanocrystals by in Situ Liquid Cell Transmission Electron Microscopy

Understanding the growth behaviors of nanomaterials during liquid-phase synthesis will be beneficial in designing and applying many functional nanodevices. However, the growth pathways regarding the nanocrystal facet development remain largely unknown as direct observation is lacking. Herein, the in situ study of Pb3O4 nanocrystals’ growth is reported by using the liquid cell transmission electron microscopy with high spatial and temporal resolution. The findings indicate that Pb3O4 nanocrystals’ growth follows distinct trajectories with shape evolution when the growth pathways are varied. Three growth pathways are observed, including the monomer growth of Pb3O4 nanocrystals, the coalescence growth of four stationary Pb3O4 nanocrystals, and the oriented attachment growth of Pb3O4 nanocrystal pairs and multiple randomly dispersed Pb3O4 nanocrystals. It is the first observation that Pb3O4 nanocrystals with a regular quadrilateral shape are formed, in which nanocrystal facets preferentially grow along the [002] direction of Pb3O4. Theoretical analysis confirms in this study that the surface energy and physical driving force play key roles in the growth of nanocrystals in a liquid. Such understanding of the growth pathways and quantification of formation kinetics are important for the design of hierarchical nanomaterials and the control of nanocrystal self-assembly for functional devices

Observing the Growth of Pb₃O₄ Nanocrystals by in Situ Liquid Cell Transmission Electron Microscopy

Understanding the growth behaviors of nanomaterials during liquid-phase synthesis will be beneficial in designing and applying many functional nanodevices. However, the growth pathways regarding the nanocrystal facet development remain largely unknown as direct observation is lacking. Herein, the in situ study of Pb3O4 nanocrystals’ growth is reported by using the liquid cell transmission electron microscopy with high spatial and temporal resolution. The findings indicate that Pb3O4 nanocrystals’ growth follows distinct trajectories with shape evolution when the growth pathways are varied. Three growth pathways are observed, including the monomer growth of Pb3O4 nanocrystals, the coalescence growth of four stationary Pb3O4 nanocrystals, and the oriented attachment growth of Pb3O4 nanocrystal pairs and multiple randomly dispersed Pb3O4 nanocrystals. It is the first observation that Pb3O4 nanocrystals with a regular quadrilateral shape are formed, in which nanocrystal facets preferentially grow along the [002] direction of Pb3O4. Theoretical analysis confirms in this study that the surface energy and physical driving force play key roles in the growth of nanocrystals in a liquid. Such understanding of the growth pathways and quantification of formation kinetics are important for the design of hierarchical nanomaterials and the control of nanocrystal self-assembly for functional devices

Observing the Growth of Pb₃O₄ Nanocrystals by in Situ Liquid Cell Transmission Electron Microscopy

Understanding the growth behaviors of nanomaterials during liquid-phase synthesis will be beneficial in designing and applying many functional nanodevices. However, the growth pathways regarding the nanocrystal facet development remain largely unknown as direct observation is lacking. Herein, the in situ study of Pb3O4 nanocrystals’ growth is reported by using the liquid cell transmission electron microscopy with high spatial and temporal resolution. The findings indicate that Pb3O4 nanocrystals’ growth follows distinct trajectories with shape evolution when the growth pathways are varied. Three growth pathways are observed, including the monomer growth of Pb3O4 nanocrystals, the coalescence growth of four stationary Pb3O4 nanocrystals, and the oriented attachment growth of Pb3O4 nanocrystal pairs and multiple randomly dispersed Pb3O4 nanocrystals. It is the first observation that Pb3O4 nanocrystals with a regular quadrilateral shape are formed, in which nanocrystal facets preferentially grow along the [002] direction of Pb3O4. Theoretical analysis confirms in this study that the surface energy and physical driving force play key roles in the growth of nanocrystals in a liquid. Such understanding of the growth pathways and quantification of formation kinetics are important for the design of hierarchical nanomaterials and the control of nanocrystal self-assembly for functional devices

Observing the Growth of Pb₃O₄ Nanocrystals by in Situ Liquid Cell Transmission Electron Microscopy

Understanding the growth behaviors of nanomaterials during liquid-phase synthesis will be beneficial in designing and applying many functional nanodevices. However, the growth pathways regarding the nanocrystal facet development remain largely unknown as direct observation is lacking. Herein, the in situ study of Pb3O4 nanocrystals’ growth is reported by using the liquid cell transmission electron microscopy with high spatial and temporal resolution. The findings indicate that Pb3O4 nanocrystals’ growth follows distinct trajectories with shape evolution when the growth pathways are varied. Three growth pathways are observed, including the monomer growth of Pb3O4 nanocrystals, the coalescence growth of four stationary Pb3O4 nanocrystals, and the oriented attachment growth of Pb3O4 nanocrystal pairs and multiple randomly dispersed Pb3O4 nanocrystals. It is the first observation that Pb3O4 nanocrystals with a regular quadrilateral shape are formed, in which nanocrystal facets preferentially grow along the [002] direction of Pb3O4. Theoretical analysis confirms in this study that the surface energy and physical driving force play key roles in the growth of nanocrystals in a liquid. Such understanding of the growth pathways and quantification of formation kinetics are important for the design of hierarchical nanomaterials and the control of nanocrystal self-assembly for functional devices

Observing the Growth of Pb₃O₄ Nanocrystals by in Situ Liquid Cell Transmission Electron Microscopy

Understanding the growth behaviors of nanomaterials during liquid-phase synthesis will be beneficial in designing and applying many functional nanodevices. However, the growth pathways regarding the nanocrystal facet development remain largely unknown as direct observation is lacking. Herein, the in situ study of Pb3O4 nanocrystals’ growth is reported by using the liquid cell transmission electron microscopy with high spatial and temporal resolution. The findings indicate that Pb3O4 nanocrystals’ growth follows distinct trajectories with shape evolution when the growth pathways are varied. Three growth pathways are observed, including the monomer growth of Pb3O4 nanocrystals, the coalescence growth of four stationary Pb3O4 nanocrystals, and the oriented attachment growth of Pb3O4 nanocrystal pairs and multiple randomly dispersed Pb3O4 nanocrystals. It is the first observation that Pb3O4 nanocrystals with a regular quadrilateral shape are formed, in which nanocrystal facets preferentially grow along the [002] direction of Pb3O4. Theoretical analysis confirms in this study that the surface energy and physical driving force play key roles in the growth of nanocrystals in a liquid. Such understanding of the growth pathways and quantification of formation kinetics are important for the design of hierarchical nanomaterials and the control of nanocrystal self-assembly for functional devices

Observing the Growth of Pb₃O₄ Nanocrystals by in Situ Liquid Cell Transmission Electron Microscopy

Understanding the growth behaviors of nanomaterials during liquid-phase synthesis will be beneficial in designing and applying many functional nanodevices. However, the growth pathways regarding the nanocrystal facet development remain largely unknown as direct observation is lacking. Herein, the in situ study of Pb3O4 nanocrystals’ growth is reported by using the liquid cell transmission electron microscopy with high spatial and temporal resolution. The findings indicate that Pb3O4 nanocrystals’ growth follows distinct trajectories with shape evolution when the growth pathways are varied. Three growth pathways are observed, including the monomer growth of Pb3O4 nanocrystals, the coalescence growth of four stationary Pb3O4 nanocrystals, and the oriented attachment growth of Pb3O4 nanocrystal pairs and multiple randomly dispersed Pb3O4 nanocrystals. It is the first observation that Pb3O4 nanocrystals with a regular quadrilateral shape are formed, in which nanocrystal facets preferentially grow along the [002] direction of Pb3O4. Theoretical analysis confirms in this study that the surface energy and physical driving force play key roles in the growth of nanocrystals in a liquid. Such understanding of the growth pathways and quantification of formation kinetics are important for the design of hierarchical nanomaterials and the control of nanocrystal self-assembly for functional devices

Additional file 2 of luxS contributes to intramacrophage survival of Streptococcus agalactiae by positively affecting the expression of fruRKI operon

Additional file 2. Primers used in this study

Comparative transcriptome combined with morphophysiological analyses revealed the molecular mechanism underlying <i>Tetrahymena thermophila</i> predation-induced antiphage defense in <i>Aeromonas hydrophila</i>

Protozoan predation has been demonstrated to be a strong driving force for bacterial defence strategies in the environment. Our previous study demonstrated that Aeromonas hydrophila NJ-35, which evolved small-colony variants (SCVs), displayed various adaptive traits in response to Tetrahymena thermophila predation, such as enhanced phage resistance. However, the evolutionary mechanisms are largely unknown. In this study, we performed a genome- and transcriptome-wide analysis of the SCV1, representing one strain of the SCVs, for identification of the genes of mutation and altered expression underlying this phage resistance phenotype. Our study demonstrated that phage resistance caused by T. thermophila predation was due to the downregulation of a flagellar biosynthesis regulator, flhF, in SCV1. Interestingly, we confirmed that phage resistance in SCV1 was not straightforwardly attributable to the absence of flagella but to FlhF-mediated secretion of extracellular protein that hinders phage adsorption. This finding improves our understanding of the mechanisms by which A. hydrophila lowers the susceptibility to phage infection under predation pressure, and highlights an important contribution of bacterium–protozoan interactions in driving the adaptive evolution of pathogens in complex environments.</p

Additional file 7 of luxS contributes to intramacrophage survival of Streptococcus agalactiae by positively affecting the expression of fruRKI operon

Additional file 7. LuxS protein could not bind to the promoter of fruRKI operon. (A) The fruRKI operon was identified in the genome of S. agalactiae GD201008-001. Lane 1. A fragment amplified by PCR from the cDNA obtained by reverse trancription. Lane 2. A fragment amplified by PCR from genomic DNA as the positive control. M. DNA marker. (B) Binding ability of LuxS protein to the fruRKI promoter. Lane 1. Negative control (25 nM of fruRKI promoter). Lane 2–4. Positive controls. Binding reaction to 25 nM of fruRKI promoter with CcpA protein at a range of concentrations from 0.6 to 1 μM. Lane 5–7. Binding reaction to 50 nM of fruRKI promoter with LuxS protein at a range of concentrations from 1 to 3 μM

Additional file 4 of luxS contributes to intramacrophage survival of Streptococcus agalactiae by positively affecting the expression of fruRKI operon

Additional file 4. The differentially expressed genes in ΔluxS compared with wild-type strain