Nanoprecipitation provides colloidal dispersions through successive recombination events between nanometric objects. In the present article, we explain why the nanoprecipitation pathways induced ...through solvent-shifting – the Ouzo effect –, are fascinating study-cases. Indeed, they allow to address the question of how the interactions between the colloidal particles control the dynamics of the process, thus the particle size distribution. Experimental monitoring of the precipitation dynamics demonstrates that the colloidal dispersion polydispersity decreases over time as the droplets coalesce. Monte Carlo simulations within the Smoluchowski framework agree quantitatively with these observations, and show how the interactions between the particles naturally force the system to become nearly monodisperse. The mechanistic understanding gained from the solvent-shifting experiments is also relevant to other nanoprecipitation processes.
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Phase diagrams are powerful tools to understand the multi-scale behaviour of complex systems. Yet, their determination requires in practice both experiments and computations, which quickly becomes a ...daunting task. Here, we propose a geometrical approach to simplify the numerical computation of liquid–liquid ternary phase diagrams. We show that using the intrinsic geometry of the binodal curve, it is possible to formulate the problem as a simple set of ordinary differential equations in an extended 4D space. Consequently, if the thermodynamic potential, such as Gibbs free energy, is known from an experimental data set, the whole phase diagram, including the spinodal curve, can be easily computed. We showcase this approach on four ternary liquid–liquid diagrams, with different topological properties, using a modified Flory–Huggins model. We demonstrate that our method leads to similar or better results comparing those obtained with other methods, but with a much simpler procedure. Acknowledging and using the intrinsic geometry of phase diagrams thus appears as a promising way to further develop the computation of multiphase diagrams.
Pure is uncharged: Uncontaminated hydrophobic interfaces, such as PMMA‐H/water interfaces, are uncharged. If the macromolecules have instead ionizable carboxylic acid endgroups, such as PMMA‐COOH, a ...surface charge similar to the contaminated oil/water interface is obtained.
Controlling water evaporation through self-assembly Roger, Kevin; Liebi, Marianne; Heimdal, Jimmy ...
Proceedings of the National Academy of Sciences - PNAS,
09/2016, Letnik:
113, Številka:
37
Journal Article
Recenzirano
Odprti dostop
Water evaporation concerns all land-living organisms, as ambient air is dryer than their corresponding equilibrium humidity. Contrarily to plants, mammals are covered with a skin that not only ...hinders evaporation but also maintains its rate at a nearly constant value, independently of air humidity. Here, we show that simple amphiphiles/water systems reproduce this behavior, which suggests a common underlying mechanism originating from responding self-assembly structures. The composition and structure gradients arising from the evaporation process were characterized using optical microscopy, infrared microscopy, and small-angle X-ray scattering. We observed a thin and dry outer phase that responds to changes in air humidity by increasing its thickness as the air becomes dryer, which decreases its permeability to water, thus counterbalancing the increase in the evaporation driving force. This thin and dry outer phase therefore shields the systems from humidity variations. Such a feedback loop achieves a homeostatic regulation of water evaporation.
Bacterial pathogens adapt and replicate within host cells, while host cells develop mechanisms to eliminate them. Using a dual proteomic approach, we characterized the intra-macrophage proteome of ...the facultative intracellular pathogen, Francisella novicida. More than 900 Francisella proteins were identified in infected macrophages after a 10-h infection. Biotin biosynthesis-related proteins were upregulated, emphasizing the role of biotin-associated genes in Francisella replication. Conversely, proteins encoded by the Francisella pathogenicity island (FPI) were downregulated, supporting the importance of the F. tularensis Type VI Secretion System for vacuole escape, not cytosolic replication. In the host cell, over 300 proteins showed differential expression among the 6200 identified during infection. The most upregulated host protein was cis-aconitate decarboxylase IRG1, known for itaconate production with antimicrobial properties in Francisella. Surprisingly, disrupting IRG1 expression did not impact Francisella's intracellular life cycle, suggesting redundancy with other immune proteins or inclusion in larger complexes. Over-representation analysis highlighted cell-cell contact and actin polymerization in macrophage deregulated proteins. Using flow cytometry and live cell imaging, we demonstrated that merocytophagy involves diverse cell-to-cell contacts and actin polymerization-dependent processes. These findings lay the groundwork for further exploration of merocytophagy and its molecular mechanisms in future research.Data are available via ProteomeXchange with identifier PXD035145.
We argue against the structural interpretation given in the paper doi.org/10.1016/j.carbpol.2020.116843 that the primary structure of gum Arabic species is a disk-like nanoparticle. We show that both ...our and Isobe et al.’s SAXS data are comparable, which demonstrates we have investigated the same type of gum Arabic. However, we also show that two-dimensional models, as first proposed by Renard, Sanchez and coworkers, fail to fit SAXS curves adequately. We have rather proposed a three-dimensional multi-scale porous structure, consistently with the three well defined correlation distances that are observed in the SAXS curves. We also briefly argue against the loosely covered schematisation of the oil/water interface chosen by the authors, which is unrealistic when discussing emulsion metastability.
Oil/surfactant/water systems may undergo phase inversion upon tuning the preferred curvature of the surfactant layer. The longstanding relationship between nanoemulsification and phase inversion is ...discussed in view of recent mechanistic advances. The name “phase inversion emulsification” is shown to result from a historical confusion. Both nanoemulsification and phase inversion are controlled by the properties of the surfactant layer but phase inversion is shown to be unnecessary to obtain nanoemulsions. Nanoemulsions can be obtained in the vicinity of phase inversion through the disruption of equilibrium bicontinuous networks. A first pathway involves a change of the interaction between the surfactant layer and water at a precise location in the parameter space and under shear. A non-equilibrium micellar solubilization of oil, named superswelling, leads to an ideal nanoemulsion after quenching. All the surfactant is used to cover the interfaces and none is wasted in the continuous phase. The sub-PIT (Phase Inversion Temperature) method falls within this category. A second pathway involves the addition of water to a water-deprived system. Oil phase separates within a bicontinuous sponge phase matrix at a precise location in the parameter space and leads to a nanoemulsion upon further addition of water. Larger droplets are obtained and some surfactant is wasted, which demonstrates that this pathway is different and less efficient, although easier to implement. It is shown that the identification of the two access states in the nanoemulsification pathways, the superswollen microemulsion and the separating sponge phase, is essential when using surfactant blends. On the contrary, phase inversion is not only irrelevant but also damaging to the success of the emulsification process.
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•Nanoemulsions can be obtained in the vicinity of phase inversion.•Undergoing phase inversion is unnecessary.•The mechanism for nanoemulsification is the disruption of bicontinuous networks.•Tuning the water/surfactant interactions leads to ideal nanoemulsification through shear-induced superswelling.•Adding water to a water-deprived system leads to nanoemulsification through templated oil phase separation.
Objective
To determine the reliability and dependability of magnetic resonance imaging (MRI) and computerized tomography (CT) in the assessment of lumbar spinal stenosis and correlate the qualitative ...assessment to both a quantitative assessment and functional outcome measures.
Summary of background data
Multiple studies have addressed the issue of CT and MRI imaging in lumbar spinal stenosis. None showed superiority of one modality.
Methods
We performed a standardized qualitative and quantitative review of CT and MRI scans of 54 patients. Intra-observer and inter-observer reliability was determined between three reviewer using Kappa coefficient. Agreement between the two modalities was analyzed. ODI and SF-36 outcomes were correlated with the imaging assessments.
Results
Almost perfect intra-observer reliability for MRI was achieved by the two expert reviewers (
κ
= 0.91 for surgeon and
κ
= 0.92 for neuro-radiologist). For CT, substantial intra-observer agreement was found for the surgeon (
κ
= 0.77) while the neuro-radiologist was higher (
κ
= 0.96). For both CT and MRI the standardized qualitative assessment used by the two expert reviewers had a better inter-observer reliability than that between the expert reviewers and the general reporting radiologist, who did not utilize a standardized assessment system. When the qualitative assessment was compared directly, CT overestimated the degree of stenosis 20–35 % of the time (
p
< 0.05) while MRI overestimated the degree of stenosis 2–11 % of the time (
p
< 0.05). No correlation was found between qualitative and quantitative analysis with functional status.
Conclusions
This study directly demonstrates that MRI is a more reliable tool than CT, but neither correlates with functional status. Both experience of the reader and the standardization of a qualitative assessment are influential to the reliability.
Impure at heart: A pH‐dependent negative charge of the interface between a hydrophobic phase and water results from the reaction of hydroxide ions with traces of fatty acids, contained in the ...hydrophobic phase (see scheme). This reaction explains the uptake of hydroxide ions by the interface with a large free energy change.
Ferroptosis constitutes a promising therapeutic strategy against cancer by efficiently targeting the highly tumorigenic and treatment-resistant cancer stem cells (CSCs). We previously showed that the ...lysosomal iron-targeting drug Salinomycin (Sal) was able to eliminate CSCs by triggering ferroptosis. Here, in a well-established breast CSCs model (human mammary epithelial HMLER CD24
/CD44
), we identified that pharmacological inhibition of the mechanistic target of rapamycin (mTOR), suppresses Sal-induced ferroptosis. Mechanistically, mTOR inhibition modulates iron cellular flux and thereby limits iron-mediated oxidative stress. Furthermore, integration of multi-omics data identified mitochondria as a key target of Sal action, leading to profound functional and structural alteration prevented by mTOR inhibition. On top of that, we found that Sal-induced metabolic plasticity is mainly dependent on the mTOR pathway. Overall, our findings provide experimental evidence for the mechanisms of mTOR as a crucial effector of Sal-induced ferroptosis pointing not only that metabolic reprogramming regulates ferroptosis, but also providing proof-of-concept that careful evaluation of such combination therapy (here mTOR and ferroptosis co-targeting) is required in the development of an effective treatment.
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